Gas diffusion electrode for use in a membrane electrolysis cell

Abstract

There is provided a gas diffusion electrode for use in a membrane electrolysis cell. There is also provided a membrane electrolysis cell for processing a salt-containing solution. There is also provided a process for producing a base product. In particular, there is provided gas diffusion electrodes within multi-compartment membrane electrolysis cells for use in processing lithium.

Description

GAS DIFFUSION ELECTRODE FOR USE IN A MEMBRANE ELECTROLYSIS CELL CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and benefit from United States Patent Application Serial No. 63 / 521,470 filed on June 16, 2023, and United States Patent Application Serial No. 63 / 592,525 filed on October 23, 2023, both of which are hereby incorporated by reference in their entirety. TECHNICAL FIELD

[0002] The present disclosure generally relates to a gas diffusion electrode (GDE) for use in a membrane electrolysis cell, to a membrane electrolysis cell comprising said GDE for processing a salt-containing solution, and to a process for producing a base product using said membrane electrolysis cell. In particular, the present disclosure relates to GDEs within multi-compartment membrane electrolysis cells for use in processing a salt-containing solution. BACKGROUND

[0003] The boom in global electric vehicle (EV) sales and the push for a transition to renewable energy has caused a dramatic increase in the demand for high-quality battery grade lithium (lithium hydroxide and lithium carbonate). By 2035, it is predicted that the most prominent automotive market segment will be fully electric vehicles.

[0004] Currently, there is a gap between the supply and demand for lithium; meaning the demand for lithium is greater than its availability. As the EV and renewable energy market continue to grow, so too will the disparity between the demand and availability of high-quality battery-grade lithium (lithium hydroxide and lithium carbonate).

[0005] Natural sources of lithium include igneous rocks, springs, sea and ocean water, as well as salar brines, which are underground reservoirs that contain high concentrations of dissolved salts, such as lithium, potassium, and sodium. These are generally found below the surface of dried lakebeds, known as salars.Extraction from Salar Brine

[0006] In general, the traditional process for the recovery of lithium from brine involves multiple pond evaporative concentration steps that remove high levels of sodium and potassium salts for instance, NaCI and KCI and possibly others by precipitation, since these are less soluble than the desired lithium salts. The evaporation thus increases the lithium concentration in the brine. Some of the magnesium in the form of precipitated MgCl2 is also removed during this evaporative stage. Next stages involve the removal of boron, calcium, magnesium as the main sources of impurity in the brine. Removal of the B, Ca and Mg ions is carried out using repeated pH adjustment, solvent extraction, and precipitation steps to ensure maximum ion removal. Ion exchange removal of leftover trace monovalent, divalent and trivalent ionic species other than the lithium further purifies the brine. Introduction of soda ash, Na2CO3, to convert the dissolved lithium salts to lithium carbonate, Li2CO3, is the last major step to produce technical and high purity lithium carbonate. Extraction from rock mining

[0007] Several minerals contain Li in their structure. For example, at least four minerals have found interest as viable Li sources. These are Lepidolite (K(Li,AI,Rb)2(AI,Si)4O10(F,OH)2), Spodumene (LiAI(SiO3)2), Petalite (LiAlSi4O10), and Amblygonite ((Li,Na)AIPO4(F,OH)). Spodumene is usually the most important ore for commercial Li production.

[0008] In general, the traditional process for the recovery of lithium from spodumene involves crushing mined ore, roasting and then cooled it, milling and roasting again with sulfuric acid in an acid leaching step. Precipitation and / or ion exchange steps may be used to remove further impurities before adding soda ash to precipitate lithium carbonate as the final product.

[0009] There is a growing need for new recovery processes and related equipment. SUMMARY

[0010] The present disclosure provides gas diffusion electrodes for use in membrane electrolysis cells. Further provided are membrane electrolysis cells comprising said gas diffusion electrodes and advantageous structural configurations thereof. The gas diffusion electrodes and membrane electrolysis cells of the present disclosure may advantageouslybe used for processing salt-containing solutions to produce one or more desired base products.

[0011] In an embodiment, the present disclosure relates to a gas diffusion electrode for use in a membrane electrolysis cell, the gas diffusion electrode comprising: a gas diffusion layer to diffuse a gas comprising oxygen; and a catalyst layer. This gas diffusion electrode is referred to herein as a GDE-1.

[0012] In an embodiment, the present disclosure relates to a GDE-1 further comprising an anion exchange membrane disposed on a surface of the catalyst layer, the anion exchange membrane being configured to exchange ions from the catalyst layer to an opposed surface of the anion exchange membrane.

[0013] In an embodiment, the present disclosure relates to a membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in the anode compartment; a cathode comprising a GDE-1 as described herein positioned to extend within the interior of the membrane electrolysis cell and positioned in the cathode compartment; a cation exchange membrane interposed between the anode compartment and the catalyst layer of the gas diffusion electrode, the cation exchange membrane being configured to exchange ions received from the anode to an opposed surface of the cation exchange membrane; an inlet through which the salt-containing solution is received into the anode compartment; a gas inlet through which a gas comprising O2 is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product of the salt solution is removed from an interior of the membrane electrolysis cell.

[0014] In an embodiment, the present disclosure relates to a process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in the immediately preceding paragraph, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the anode compartment; the positive salt ions migrate through the cation exchange membrane to the opposed surface of the cation exchange membrane into the cathode compartment; the gas comprising O2 is reduced at the cathodeto form OH-; the OH- ions combine with the positive salt ions to produce the base product; and the base product is removed from the cathode compartment.

[0015] In an embodiment, the present disclosure relates to a membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up compartment interposed between the cathode compartment and the anode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a GDE-1 as described herein positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; an anion exchange membrane being disposed on the catalyst layer of the gas diffusion electrode and being configured to exchange ions received from the catalyst layer of the gas diffusion electrode to an opposed surface of the anion ion exchange membrane into the base build-up compartment; a cation exchange membrane interposed between the anode compartment and the base build up compartment, the cation exchange membrane being configured to exchange ions received from the anode to an opposed surface of the cation exchange membrane into the base build-up compartment; an inlet through which the salt-containing solution is received into the anode compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2 is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

[0016] In an embodiment, the present disclosure relates to a process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in the immediately preceding paragraph, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the anode compartment; the positive salt ions migrate through the cation exchange membrane to the opposed surface of the cation exchange membrane into the base build-up compartment; the gas comprising O2is reduced at the cathode to form OH-; the OH- ions migrate through the anion exchange membrane to the opposed surface of the anion exchange membrane into the base build up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the base build-up compartment.

[0017] In an embodiment, the present disclosure relates to a membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up compartment and a salt depletion compartment interposed between the cathode compartment and the anode compartment, the base build-up compartment is interposed between the cathode compartment and the salt depletion compartment, and the salt depletion compartment is interposed between the base build-up compartment and the anode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a GDE-1 as described herein positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a first anion exchange membrane being disposed on the catalyst layer of the gas diffusion electrode and being configured to exchange ions received from the catalyst layer of the gas diffusion electrode to an opposed surface of the first anion ion exchange membrane into the base build-up compartment; a cation exchange membrane interposed between the salt depletion compartment and the base build-up compartment, the cation exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the cation exchange membrane into the base build-up compartment; a second anion exchange membrane interposed between the salt depletion compartment and the anode compartment, the second anion exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the second anion exchange membrane into the anode compartment; an inlet through which the salt-containing solution is received into the salt depletion compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

[0018] In an embodiment, the present disclosure relates to a process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in the immediately preceding paragraph, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the salt depletion compartment; the positive salt ions migrate through the cation exchange membrane to the opposed surface of the cation exchange membrane into the base build-up compartment; the gas comprising O2 is reducedat the cathode to form OH-; the OH- ions migrate through the first anion exchange membrane to the opposed surface of the first anion exchange membrane into the base build-up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the base build-up compartment.

[0019] In an embodiment, the present disclosure relates to a membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up compartment, a salt depletion compartment and an acid build-up compartment interposed between the cathode compartment and the anode compartment, the base build-up compartment is interposed between the cathode compartment and the salt depletion compartment, the salt depletion compartment is interposed between the base build-up compartment and the acid build-up compartment, and the acid build-up compartment is interposed between the salt depletion compartment and the anode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a GDE-1 as described herein positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a first anion exchange membrane, the first anion exchange membrane being disposed on the catalyst layer of the gas diffusion electrode and being configured to exchange ions received from the catalyst layer of the gas diffusion electrode to an opposed surface of the first anion ion exchange membrane into the base build-up compartment; a first cation exchange membrane interposed between the salt depletion compartment and the base build-up compartment, the cation exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the cation exchange membrane into the base build- up compartment; a second anion exchange membrane interposed between the salt depletion compartment and the acid build-up compartment, the second anion exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the second anion exchange membrane into the acid build-up compartment; a second cation exchange membrane interposed between the acid build-up compartment and the anode compartment, the second cation exchange membrane being configured to exchange ions received from the anode compartment to an opposed surface of the second cation exchange membrane into the acid build-up compartment; an inlet through which the salt-containing solution is received into the salt depletion compartment; a gas inletpositioned in the cathode compartment through which the gas comprising O2 is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

[0020] In an embodiment, the present disclosure relates to a process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in the immediately preceding paragraph, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the salt depletion compartment; the positive salt ions migrate through the first cation exchange membrane to the opposed surface of the cation exchange membrane into the base build-up compartment; the gas comprising O2 is reduced at the cathode to form OH-; the OH- ions migrate through the first anion exchange membrane to the opposed surface of the first anion exchange membrane into the base build-up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the base build-up compartment.

[0021] In an embodiment, the present disclosure relates to a gas diffusion electrode for use in a membrane electrolysis cell, the gas diffusion electrode comprising: a gas diffusion layer to diffuse a gas comprising oxygen; and a catalyst coated membrane comprising a catalyst layer disposed on a surface of a membrane. This gas diffusion electrode is referred to herein as a GDE-2.

[0022] In an embodiment, the present disclosure relates to a membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up compartment interposed between the cathode compartment and the anode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a GDE-2 as described herein positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a cation exchange membrane interposed between the anode compartment and the base build-up compartment, the cation exchange membrane being configured to exchange ions received from the anode to an opposed surface of the cation exchange membrane into the base build-up compartment; an inlet through which the salt-containing solution is receivedinto the anode compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2 is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

[0023] In an embodiment, the present disclosure relates to a process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in the immediately preceding paragraph, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the anode compartment; the positive salt ions migrate through the cation exchange membrane to the opposed surface of the cation exchange membrane into the base build-up compartment; the gas comprising O2is reduced at the cathode to form OH-; the OH- ions migrate through the catalyst coated membrane into the base build-up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the base build-up compartment.

[0024] In an embodiment, the present disclosure relates to a membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up compartment and a salt depletion compartment interposed between the cathode compartment and the anode compartment, the base build-up compartment is interposed between the cathode compartment and the salt depletion compartment, and the salt depletion compartment is interposed between the base build-up compartment and the anode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a GDE-2 as described herein positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a cation exchange membrane interposed between the salt depletion compartment and the base build-up compartment, the cation exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the cation exchange membrane into the base build-up compartment; an anion exchange membrane interposed between the salt depletion compartment and the anode compartment, the anion exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the anion exchange membrane into the anodecompartment; an inlet through which the salt-containing solution is received into the salt depletion compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

[0025] In an embodiment, the present disclosure relates to a process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in the immediately preceding paragraph, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the salt depletion compartment; the positive salt ions migrate through the cation exchange membrane to the opposed surface of the cation exchange membrane into the base build-up compartment; the gas comprising O2is reduced at the cathode to form OH-; the OH- ions migrate through the catalyst coated exchange membrane into the base build-up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the base build-up compartment.

[0026] In an embodiment, the present disclosure relates to a membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up compartment, a salt depletion compartment and an acid build-up compartment interposed between the cathode compartment and the anode compartment, the base build-up compartment is interposed between the cathode compartment and the salt depletion compartment, the salt depletion compartment is interposed between the base build-up compartment and the acid build-up compartment, and the acid build-up compartment is interposed between the salt depletion compartment and the anode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a GDE-2 as described herein positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a first cation exchange membrane interposed between the salt depletion compartment and the base build-up compartment, the cation exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the cation exchange membrane into the base build-up compartment; an anion exchange membrane interposed between the salt depletion compartment and the acid build-up compartment, the anionexchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the anion exchange membrane into the acid build-up compartment; a second cation exchange membrane interposed between the acid build-up compartment and the anode compartment, the second cation exchange membrane being configured to exchange ions received from the anode compartment to an opposed surface of the second cation exchange membrane into the acid build-up compartment; an inlet through which the salt-containing solution is received into the salt depletion compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2 is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

[0027] In an embodiment, the present disclosure relates to a process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in the immediately preceding paragraph, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the salt depletion compartment; the positive salt ions migrate through the first cation exchange membrane to the opposed surface of the first cation exchange membrane into the base build-up compartment; the gas comprising O2 is reduced at the cathode to form OH-; the OH- ions migrate through the catalyst coated membrane into the base build-up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the base build-up compartment.

[0028] In an embodiment, the present disclosure relates to a gas diffusion electrode for use in a membrane electrolysis cell, the gas diffusion electrode comprising: a gas diffusion layer to diffuse a gas comprising oxygen; and a catalyst layer disposed on the gas diffusion layer, wherein the catalyst layer has a thickness optimized to substantially or completely consume a liquid reactant diffusing across the catalyst layer before reaching the gas diffusion layer. This gas diffusion electrode is referred to herein as a GDE-3.

[0029] In an embodiment, the present disclosure relates to a membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up together with the cathode compartment forming a single compartment; an anode positioned to extend within the interiorof the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a GDE-3 as described herein positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a cation exchange membrane interposed between the anode compartment and the base build-up compartment, the cation exchange membrane being configured to exchange ions received from the anode to an opposed surface of the cation exchange membrane into the base build-up compartment; an inlet through which the salt-containing solution is received into the anode compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

[0030] In an embodiment, the present disclosure relates to a process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in the immediately preceding paragraph, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the anode compartment; the positive salt ions migrate through the cation exchange membrane to the opposed surface of the cation exchange membrane into the base build-up compartment; the gas comprising O2 is reduced at the cathode to form OH-; the OH- ions migrate through the catalyst layer into the base build-up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the membrane electrolysis cell.

[0031] In an embodiment, the present disclosure relates to a membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up together with the cathode compartment forming a single compartment; a salt depletion compartment interposed between the cathode compartment and the anode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a GDE-3 as described herein positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a cation exchange membrane interposed between the salt depletion compartment and the base build-up compartment, the cation exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the cationexchange membrane into the base build-up compartment; an anion exchange membrane interposed between the salt depletion compartment and the anode compartment, the anion exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the anion exchange membrane into the anode compartment; an inlet through which the salt-containing solution is received into the salt depletion compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

[0032] In an embodiment, the present disclosure relates to a process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in the immediately preceding paragraph, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the salt depletion compartment; the positive salt ions migrate through the cation exchange membrane to the opposed surface of the cation exchange membrane into the base build-up compartment; the gas comprising O2 is reduced at the cathode to form OH-; the OH- ions migrate through the catalyst layer into the base build-up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the membrane electrolysis cell.

[0033] In an embodiment, the present disclosure relates to a membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up together with the cathode compartment forming a single compartment; a salt depletion compartment and an acid build up compartment interposed between the cathode compartment and the anode compartment, the salt depletion compartment is interposed between the base build-up compartment and the acid build-up compartment, and the acid build-up compartment is interposed between the salt depletion compartment and the anode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a GDE-3 as described herein positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a first cation exchange membrane interposed between the salt depletion compartment and the base build-up compartment, the cation exchange membrane being configured to exchange ionsreceived from the salt depletion compartment to an opposed surface of the cation exchange membrane into the base build-up compartment; an anion exchange membrane interposed between the salt depletion compartment and the acid build-up compartment, the anion exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the anion exchange membrane into the acid build-up compartment; a second cation exchange membrane interposed between the acid build-up compartment and the anode compartment, the second cation exchange membrane being configured to exchange ions received from the anode compartment to an opposed surface of the second cation exchange membrane into the acid build-up compartment; an inlet through which the salt-containing solution is received into the salt depletion compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

[0034] In an embodiment, the present disclosure relates to a process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in the immediately preceding paragraph, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the salt depletion compartment; the positive salt ions migrate through the first cation exchange membrane to the opposed surface of the first cation exchange membrane into the base build-up compartment; the gas comprising O2is reduced at the cathode to form OH-; the OH- ions migrate through the catalyst layer into the base build-up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the membrane electrolysis cell.

[0035] In an embodiment, the present disclosure relates to a gas diffusion electrode for use in a membrane electrolysis cell, the gas diffusion electrode comprising: a first gas diffusion layer to diffuse a gas comprising oxygen; a catalyst layer disposed on a surface of the first gas diffusion layer; a second gas diffusion layer contacting a surface of the catalyst layer opposite the first gas diffusion layer; and an ionomer layer disposed on a surface of an anion exchange membrane, the ionomer layer is in contact with a surface of the second gas diffusion layer opposite the catalyst layer. This gas diffusion electrode is referred to herein as a GDE-4. In an embodiment, the GDE-4 further comprises a microporous layer disposedon a surface of the second gas diffusion layer, wherein the microporous layer is in contact with the surface of the catalyst layer opposite the first gas diffusion layer.

[0036] In an embodiment, the present disclosure relates to a GDE for use in a membrane electrolysis cell, the GDE comprising a gas diffusion layer to diffuse a gas comprising oxygen and a catalyst layer disposed on a surface of the diffusion layer. In certain embodiments, the catalyst layer comprises a catalyst and an ionomer in an ionomer:catalyst ratio of between 1:1 to 1:20.

[0037] In an embodiment, the present disclosure relates to a GDE for use in a membrane electrolysis cell, the GDE comprising a gas diffusion layer to diffuse a gas comprising oxygen, a microporous layer disposed on a surface of the gas diffusion layer, and a catalyst layer disposed on a surface of the microporous layer. In certain embodiments, the catalyst layer comprises a catalyst and an ionomer in an ionomer:catalyst ratio of between 1:1 to 1:20.

[0038] In an embodiment, the present disclosure relates to a membrane electrolysis cell for producing a base, the membrane electrolysis cell comprising a gas diffusion electrode (GDE) configured as an oxygen depolarized cathode to catalyze the following reaction: O2 + 2H2O + 4e- > $)&-. In certain embodiments, the GDE comprises a gas diffusion layer to diffuse a gas comprising oxygen and a catalyst layer disposed on a surface of the diffusion layer, wherein the catalyst layer comprises a catalyst and an ionomer in an ionomer-to-catalyst ratio of between 1:1 to 1:20.

[0039] In an embodiment, the present disclosure relates to a membrane electrolysis cell for producing a base, the membrane electrolysis cell comprising a gas diffusion electrode (GDE) configured as an oxygen depolarized cathode to catalyze the following reaction: O2 + 2H2O + 4e- > $)&-. In certain embodiments, the GDE comprises a gas diffusion layer to diffuse a gas comprising oxygen, a microporous layer disposed on a surface of the diffusion layer, and a catalyst layer disposed on a surface of the microporous layer, wherein the catalyst layer comprises a catalyst and an ionomer in an ionomer-to-catalyst ratio of between 1:1 to 1:20.

[0040] In an embodiment, the present disclosure relates to a membrane coated GDE for use in a membrane electrolysis cell as disclosed herein or any other membraneelectrolysis cell, the membrane coated GDE comprising: a GDE comprising a GDL to diffuse a gas comprising oxygen and a catalyst layer; and an AEM coated on the GDE.

[0041] In an embodiment, the present disclosure relates to a process for preparing a membrane coated gas diffusion electrode, the process comprising: mixing an ionomer in a solvent to prepare a coating mixture; applying the coating mixture to a gas diffusion electrode, and curing to form the membrane coated gas diffusion electrode.

[0042] Other aspects and embodiments of the disclosure are evident in view of the detailed description provided herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Further advantages, permutations and combinations of the disclosure will now appear from the above and from the following detailed description of the various particular embodiments of the present disclosure taken together with the accompanying drawings, each of which are intended to be non limiting, in which:

[0044] FIG. 1 is a structural diagram of eight exemplary gas diffusion electrodes of the present disclosure (GDE-1) comprising at least a catalyst layer (CL) and a gas diffusion layer (GDL) (panel (a)), and in some exemplary embodiments of the GDE-1 further comprising: a microporous layer (MPL); a mesh; an anion exchange membrane (AEM); or a combination thereof (panels (b), (c), (d), (e), (f), (g) and (h)).

[0045] FIG.2 is a structural diagram of four exemplary gas diffusion electrodes of the present disclosure (GDE-2) comprising at least a gas diffusion layer and a catalyst coated membrane (CCM) (panel (a)), and in some exemplary embodiments of the GDE-2 further comprising: a microporous layer (MPL); a mesh; or a combination thereof (panels (b), (c) and (d)).

[0046] FIG. 3 is a structural diagram of two 3-D exemplary gas diffusion electrodes of the present disclosure (GDE-3) comprising at least a gas diffusion layer (GDL) and a catalyst layer (CL) with a thickness (x) configured to consume a liquid reactant diffusing towards the GDL (panel (a)), and in another exemplary embodiment further comprising a mesh (panel (b)).

[0047] FIG.4 is a structural diagram of four exemplary gas diffusion electrodes of the present disclosure (GDE-4) comprising at least a first gas diffusion layer (1stGDL) and a catalyst layer (CL), an ionomer layer (IL) and an anion exchange membrane (AEM), and a second gas diffusion layer (2ndGDL) therebetween (panel (a)), and in some exemplary embodiments of the GDE-4 further comprising: a microporous layer (MPL); a mesh; or a combination thereof (panels (b), (c) and (d)).

[0048] FIG. 5 is a schematic diagram of an exemplary 5-compartment membrane electrolysis cell of the present disclosure showing feed and product streams.

[0049] FIG. 6 is a diagram of an exemplary 4-compartment membrane electrolysis cell of the present disclosure showing feed and product streams.

[0050] FIG. 7 is a diagram of an exemplary 3-compartment membrane electrolysis cell of the present disclosure showing feed and product streams.

[0051] FIG. 8 is a diagram of an exemplary 2-compartment membrane electrolysis cell of the present disclosure showing feed and product streams.

[0052] FIG. 9 is a process flow diagram for use of an embodiment of the membrane electrolysis cell as incorporated into a process for Li recovery from brine.

[0053] FIG.10 is a process flow diagram for use of an embodiment of the membrane electrolysis cell as incorporated into a process for Li extraction from mineral rock.

[0054] FIG. 11 is a process flow diagram for use of an embodiment of onsite LiOH and Li2CO3 and HCl generation from LiCl brine as incorporated into a Li recovery process / 7648*3*7 +725.8 += 91. ,65;.782656 / '2%3 > '2)&"&%3#

[0055] FIG.12 is a process flow diagram of an embodiment of onsite LiOH and Li2CO3and HCl generation from LiCl brine as incorporated into a recovery process of Li from salar +725.8 += 91. ,65;.782656 / '2%3 > '2)&"&%3#

[0056] FIG. 13 is a process flow diagram of an embodiment of onsite crystallized LiOH generation from mixed LiCl and NaCl brine as incorporated into a recovery process of '2 / 7648*3*7 +725.8 += 91. ,65;.782656 / '2%3 > '2)&"&%3 *5- += 91. ,65;.782652591.8*4. ,.336 / (*%3 > (*)&"&%3#

[0057] FIG.14 is a process flow diagram of an embodiment of onsite LiOH and H2SO4generation from Li2SO4 as incorporated mid-stream into a process of lithium recovery in a hard rock mining operation by the conversion of Li2SO4> '2)&"&2SO4;

[0058] FIG. 15 is a process flow diagram of an embodiment of LiOH production from Li2CO3, where HCl is produced and is recycled to dissolve the Li2CO3 in a closed-loop process.

[0059] FIG. 16 is a process flow diagram of an embodiment of LiOH production as incorporated into a recovery process of Li from a lithium brine by the selective adsorption of '2 :8250 *5265 .<,1*50. 7.825 += 91. ,65;.782656 / '2%3 > '2)&"&%38:,191*991. &%328 used to regenerate the ion exchange resin.

[0060] FIG. 17 is a process flow diagram of another embodiment of LiOH production as incorporated into a recovery process of Li from a lithium brine by the selective adsorption 6 / '2 :8250 *5265.<,1*50.7.825 += 91. ,65;.782656 / '2%3 > '2)&"&%38:,191*991. &%328 used to regenerate the ion exchange resin.

[0061] FIG. 18 is a process flow diagram of an embodiment of alkali (e.g. LiOH) production as incorporated into a recovery process of Li from a Li source by selective extraction of Li using a solvent extraction (SX) method and electrolysis of lithium salt-containing solution. DETAILED DESCRIPTION

[0062] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosure belongs. Although any methods and materials similar to or equivalent to those described herein can be used in the practice or testing of the present disclosure, the suitable methods and materials are described below.

[0063] The present disclosure pertains to gas diffusion electrodes (GDEs) for use in a membrane electrolysis cell, to membrane electrolysis cells comprising the GDEs for processing a salt-containing solution, and to processes using the membrane electrolysis cells for producing a base product.

[0064] In an embodiment, the salt-containing solution comprises LiCl, Li2SO4, Li3PO4, LiNO3, LiI, NaCl, Na2SO4, Na3PO4, NaNO3, NaI, KCl, K2SO4, K3PO4, KNO3, or KI, or a combination thereof.

[0065] In an embodiment, the base product comprises LiOH, NaOH, or KOH, or a combination thereof.

[0066] The present disclosure provides a number of advantages over certain existing technologies. An advantage of the present disclosure is the provision of unique GDEs and their use within multi-compartment membrane electrolysis cells that can use ambient undried, humid air as a source of oxygen. The disclosed GDEs, according to some embodiments, are used only at or within the cathode compartment of the membrane electrolysis cells as disclosed herein.

[0067] According to additional aspects, the present disclosure advantageously makes it possible to improve Li extraction from various sources, including brine sources or lithium ore sources where hydrochloric acid, sodium hydroxide, and / or sulfuric acid may be required; eliminate the need to outsource the acid and base feed materials by utilizing the already available brine onsite, whether derived from salar brine or a brine solution that is produced in the lithium ore refining process or a brine produced during a lithium ion battery recycling process; directly convert lithium containing salts, e.g. lithium chloride or lithium sulfate, to higher value lithium hydroxide or lithium carbonate product; provide a membrane electrolysis cell for improved processing of salt-containing solutions; and / or provide a process for production of lithium hydroxide or lithium carbonate using a membrane electrolysis cell.

[0068] As used herein, the terms “oxygen depolarized cathode”, “ODC”, “gas diffusion cathode” or “GDC” may be used interchangeably and / or refer to the same structure, which is used for example, as the cathode in a membrane electrolysis cell. In embodiments of the present disclosure, such cathode structures may comprise a GDE of the present disclosure.

[0069] As used herein, the terms “membrane electrode assembly” or “MEA” may be used interchangeably and refer to an ion exchange membrane disposed on a gas diffusion electrode (GDE).

[0070] As used herein, the term “disposed on” is intended to refer to any manner in which one substrate or material is placed on or in contact with another in a permanent or consistent manner. For example, “disposed thereon” may be used to refer to one substrate or material being affixed to another, sprayed onto another, coated onto another, hot pressed onto another, teflonized onto another, laminated onto another, placed adjacent and in contact with another, or any other means in which the first substrate or material may be placed on or in contract with a second substrate or material.

[0071] As used herein, the term “porosity” refers to the percentage of void space in a material. In an embodiment, it represents the ratio of the volume of the void or pore space in a material, divided by the total volume. For example, if half of the volume of a material is void or pore space, then the porosity of the material is 50%.

[0072] Gas Diffusion Electrode (GDE)

[0073] In an embodiment, the present disclosure relates to a gas diffusion electrode (GDE) for use in a membrane electrolysis cell.

[0074] The gas diffusion electrode comprises a porous catalyst layer which is disposed on carrier material. The catalyst layer, which conducts electrons, catalyses an electrochemical reaction between a liquid and a gas. Thus, the electrochemical reaction occurs at a so-called three-phase boundary where gas, liquid and solid (i.e. catalyst) are contacted.

[0075] In an embodiment, the gas may comprise oxygen and the liquid may comprise water resulting in the cathodic reaction: O2+ 2H2O + 4e- > $)&-

[0076] In this case, the GDE allows for a membrane electrolysis cell to operate using air as the oxygen source at the cathode. This may be a significant economic and safety advance in the ability to incorporate these cells into a process for producing a base (e.g. alkali metal compounds such as alkali metal hydroxides).

[0077] In a further embodiment, the gas may comprise oxygen admixed with carbon dioxide resulting in the following cathodic reactions:O2 + 2H2O + 4e- > $)&- OH- + CO2 > &%)3- HCO3- + OH- > %)32-+ H2O

[0078] In this embodiment, it may be possible to electrochemically produce alkali metal carbonates and bicarbonates.

[0079] Various embodiments of GDEs in accordance with the present disclosure are described below by reference to “GDE-1”, “GDE-2” and “GDE-3”. Non-limiting configurations of these GDE embodiments are shown in FIG. 1 (GDE-1), FIG. 2 (GDE-2), FIG.3 (GDE-3) and FIG. 4 (GDE-4).

[0080] As will be appreciated by the skilled person having regard to the present disclosure, the GDEs may be prepared by any of the numerous methods known in the art for applying a catalyst layer to a substrate (e.g. GDL or membrane). The form of the catalyst layer preparation will influence the choice of method. For example, solid / powder (e.g. dry powder spraying, decal method), suspension (e.g. Doctor Blade, screen printing, inkjet printing, scrape method), aerosol (e.g. sonicated spray, irradiation spray, hand brush air spray), vapour / plasma (e.g. magnetron sputtering, decal sputtering, helican RF sputtering, chemical vapour deposition), electrode assisted deposition (e.g. electrode spraying, electrodeposition, or electrophoretic deposition). In an embodiment, the catalyst layer is a suspension and may be applied by way of, for example and without limitation, Doctor Blade, screen printing, inkjet printing, or scrape method. GDE-1

[0081] In an aspect of the present disclosure, there is provided a gas diffusion electrode (GDE-1) comprising a gas diffusion layer (GDL) and a catalyst layer (CL). In an embodiment, the CL is disposed on a surface of the GDL. See, for example, FIG.1(a).

[0082] In another embodiment, the GDL of GDE-1 may be modified with a hydrophobic polymer treatment and / or application of a microporous layer (MPL). In an embodiment, the GDE further comprises the MPL disposed on a surface of the GDL, wherein the CL is disposed on a surface of the microporous layer opposite the GDL. See, for example, FIG. 1(b).

[0083] In yet another embodiment, GDE-1 may include a mesh in contact with a surface of the GDL opposite from the CL (see, for example, FIG. 1(c)) or opposite from the MPL (see, for example, FIG. 1(d)). In an embodiment, the mesh is bonded to the GDL by teflonization, hot-pressing, or lamination.

[0084] In still another embodiment, GDE-1 includes an anion exchange membrane (AEM) which may assist in the prevention of GDE flooding by the liquid reactant in an electrochemical cell. In an embodiment, the AEM may be disposed on a surface of the CL, the AEM being configured to exchange ions from the catalyst layer to an opposed surface of the AEM. See, for example, FIGs.1(e)-1(h). The AEM may be held in direct contact with the CL through a mechanical means or the AEM is bonded to the CL, for example, by teflonization, hot-pressing, ionomer, or lamination. Alternatively, the AEM may be coated onto the GDE. For example, an anion exchange ionomer may be mixed in a solvent to prepare a coating mixture, the coating mixture may be applied to the GDE, and subsequently cured (e.g. with heat) to form the AEM coated GDE.

[0085] Thus, in another embodiment of the present disclosure, there is provided a membrane coated GDE for use in a membrane electrolysis cell as disclosed herein or other, the membrane coated GDE comprising: a GDE comprising a GDL to diffuse a gas comprising oxygen and a catalyst layer; and an ion exchange membrane coated on the GDE.

[0086] In yet another embodiment of the present disclosure, there is provided a process for preparing a membrane coated GDE of the present disclosure, the process comprising: mixing an ionomer in a solvent to prepare a coating mixture; applying the coating mixture to a GDE, and curing to form the membrane coated GDE. The ionomer may be or comprise any suitable anion exchange ionomer, such as for example any of the anion exchange ionomers disclosed herein or any mixture thereof. In an embodiment, the ionomer comprises a FumionTMionomer, an IonomrTMionomer, a Sustainion® ionomer, an Orion ionomer, a PentionTMionomer, or a PiperION ionomer.

[0087] The ionomer may be mixed with the solvent in any suitable manner, including without limitation stirring, blending, tumbling, spraying, etc. The solvent may be appropriately selected based on the ionomer that is used. In an embodiment, the solvent is an aqueous-based solvent or an oil-based solvent. In an embodiment, the solvent is an alcohol.In an embodiment, the solvent is ethanol, methanol, propanol, isopropanol, butanol, ethylene glycol, glycerol, isobutanol, or any other suitable alcohol.

[0088] The amount of ionomer that is mixed with the solvent may be dependent upon one or both of the type of ionomer used and the solvent used. In an embodiment, the ionomer is mixed in the solvent at a concentration of between about 0.5 wt.% and about 25 wt.%, more particularly between about 1 wt.% and about 20 wt.%, and more particularly still between about 2 wt.% and about 15 wt.%. In an embodiment, the ionomer is mixed in the solvent at a concentration of between about 1 wt.% and about 5 wt.%. In an embodiment, the ionomer is mixed in the solvent at a concentration of between about 5 wt.% and about 10 wt.%. In an embodiment, the ionomer is mixed in the solvent at a concentration of between about 10 wt.% and about 15 wt.%. In an embodiment, the ionomer is mixed in the solvent at a concentration of about 1 wt.%, about 2 wt.%, about 3 wt.%, about 4 wt.%, about 5 wt.%, about 6 wt.%, about 7 wt.%, about 8 wt.%, about 9 wt.%, about 10 wt.%, about 11 wt.%, about 12 wt.%, about 13 wt.%, about 14 wt.%, about 15 wt.%, about 16 wt.%, about 17 wt.%, about 18 wt.%, about 19 wt.%, about 20 wt.%, about 21 wt.%, about 22 wt.%, about 23 wt.%, about 24 wt.%, or about 25 wt.%.

[0089] In an embodiment, the step of applying the coating mixture to the GDE is at a sufficient amount to provide a coat thickness of between about 10 µm and about 250 µm, more particularly between about 10 µm and about 100 µm, and more particularly still between about 20 µm and 100 µm. In an embodiment, the thickness of the coating mixture is between about 10 µm to about 75 µm. In an embodiment, the thickness of the coating mixture is between about 10 µm to about 50 µm. In an embodiment, the thickness of the coating mixture is between about 25 µm to about 50. In an embodiment, the thickness of the coating mixture is about 10 µm, about 15 µm, about 20 µm, about 25 µm, about 30 µm, about 35 µm, about 40 µm, about 45 µm, about 50 µm, about 55 µm, about 60 µm, about 65 µm, about 70 µm, about 75 µm, about 80 µm, about 85 µm, about 90 µm, about 95 µm, or about 100 µm. This may be the thickness as applied or the thickness after curing. As will be appreciated, if a particular thickness is desired after curing, a slightly thicker coating mixture may need to be applied.

[0090] The step of curing may be by any suitable means, including without limitation heating, ultraviolet (UV) radiation, infrared radiation, etc. In an embodiment, the curing is performed by heating. Without limitation, the heating may be in an oven or within some otherfully or partially closed device, application of heat by a dryer, blower or other device, contracting with a heated surface, or any other suitable form of applying heat. In an embodiment, the curing by heating is at a temperature of between about 25oC and about 200oC, more particularly between about 40oC and about 150oC, and more particularly still between about 50oC and about 140oC. In an embodiment, the curing by heating is at a temperature of about 50oC, about 550oC, about 60oC, about 65oC, about 70oC, about 75oC, about 80oC, about 85oC, about 90oC, about 95oC, about 100oC, about 105oC, about 110oC, about 115oC, about 120oC, about 125oC, about 130oC, about 135oC, about 140oC, about 145oC, or about 150oC. GDE-2

[0091] In another aspect of the present disclosure, there is provided a gas diffusion electrode (GDE-2) comprising a gas diffusion layer (GDL) and a catalyst coated membrane (CCM). In an embodiment, the CL is disposed on a surface of a membrane to form the CCM. See, for example, see FIG.2(a).

[0092] In an embodiment, the CCM refers to the anion exchange membrane having one surface coated with the CL. The CCM may allow for better ion transport through the contact interface between the CL and membrane. In an embodiment, the GDL is in contact with the CL of the CCM.

[0093] In another embodiment, the GDL of GDE-2 may be modified with a hydrophobic polymer treatment and / or application of a microporous layer (MPL). In an embodiment, the GDE further comprises the MPL disposed on a surface of the GDL, wherein the MPL is in contact with the CL of the CCM. See, for example, FIG. 2(b).

[0094] In yet another embodiment, GDE-2 may include a mesh in contact with a surface of the GDL opposite from the CL (see, for example, FIG. 2(c)) or opposite from the MPL (see, for example, FIG. 2(d)). In an embodiment, the mesh is bonded to the GDL by teflonization, hot-pressing, or lamination. GDE-3

[0095] In another aspect of the present disclosure, there is provided a gas diffusion electrode (GDE-3) comprising a gas diffusion layer (GDL) and a catalyst layer (CL) disposed on the GDL, wherein the catalyst layer has a thickness (x) optimized to substantially orcompletely consume a liquid reactant diffusing across the CL before reaching the GDL. See, for example, see FIG. 3(a).

[0096] As the liquid reactant diffuses across the CL of GDE-3, it will be consumed due to electrochemical reaction. Consequently, a concentration gradient of the reacting species will develop across the depth of the CL. In an embodiment, the final concentration of the liquid reactant may be zero or near zero at the interface between the CL and GDL. By “near zero”, it is meant a moisture content at the interface between the CL and the GDL that is of an amount insufficient to adversely affect the electrochemical reaction of the GDE. In an embodiment, the moisture content at the surface of the CL at the interface between the CL and GDL is an amount less than 5%, less than 4%, less than 3%, less than 2%, less than 1% of the liquid reactant. By controlling the thickness, and optionally the hydrophobicity and / or porosity of the CL, one may control the concentration gradient to ensure more complete utilization of the reactant. With sufficient reaction of the liquid reactant in the CL, use of an ion exchange membrane with GDE-3 may be rendered unnecessary in an electrochemical cell.

[0097] In an embodiment, GDE-3 may include a mesh in contact with a surface of the GDL opposite from the CL (see, for example, FIG. 3(b)). In an embodiment, the mesh is bonded to the GDL by teflonization, hot-pressing, or lamination. GDE-4

[0098] In an aspect of the present disclosure, there is provided a gas diffusion electrode (GDE-4) comprising a first gas diffusion layer (1stGDL), a catalyst layer (CL), a second gas diffusion layer (2ndGDL), an ionomer layer (IL), and an anion exchange membrane (AEM). In an embodiment, the CL is disposed on a surface of the 1stGDL. In another embodiment, a surface of the 2ndGDL is in contact with the CL. In a further embodiment, the IL is bonded to the AEM. In yet a further embodiment, the IL is in contact with a surface of the 2ndGDL opposite from the CL. See, for example, FIG. 4(a).

[0099] In another embodiment, the 2ndGDL of GDE-4 may be modified with a hydrophobic polymer treatment and / or application of a microporous layer (MPL). In an embodiment, the GDE further comprises the MPL disposed on a surface of the 2ndGDL. In this embodiment, the MPL is in contact with the CL. See, for example, FIG.4(b).

[0100] In yet another embodiment, GDE-4 may include a mesh in contact with a surface of the 1stGDL opposite from the CL (see, for example, FIG. 4(c) or (d)).

[0101] As described, the GDE-4 comprises a 1stGDL and a 2ndGDL. In an embodiment, the 1stGDL and 2ndGDL in the GDE-4 are the same. In another embodiment, the 1stGDL and 2ndGDL in the GDE-4 are different from each other. For example, the 1stGDL and 2ndGDL may have the same or different pore configurations, have the same or different porosity, be the same or different thickness, be made of the same or different materials (e.g. any of (1a)-(5f) described herein), be modified or not with a hydrophobic polymer treatment and / or application of a microporous layer, or any combination thereof selected independently for each of the 1stGDL and the 2ndGDL.

[0102] The surfaces of any of the GDEs described herein, or the surfaces of any of the AEMs disposed on the GDEs described herein, may have an embossed / debossed pattern to effectively increase the active surface area. The pattern may be applied by any known method including carving, molding and stamping. The pattern may be any suitable pattern that increases the surface area of the substrate or material.

[0103] Embodiments of various features of the above-described GDEs will now be described in further detail, such as the GDL, MPL, and CL. Gas Diffusion Layer (GDL)

[0104] The GDL is a porous structure that may act as a gas diffuser and / or a current collector. In an embodiment, the GDL may have relatively uniform pore size through its thickness. In another embodiment, the GDL may have a random pore size through its thickness. In yet another embodiment, the GDL may have a pore size gradient through its thickness. For example, the GDL may have a gradient of large to small pore size through its thickness in the direction of gas flow. Alternatively, the GDL may have a gradient of small to large pore size through its thickness in the direction of gas flow.

[0105] The GDL may have a thickness of between 50 µm and 1000 µm, between 50 µm and 950 µm, between 50 µm and 900 µm, between 50 µm and 850 µm, between 50 µm and 800 µm, between 50 µm and 750 µm, between 50 µm and 700 µm, between 50 µm and 650 µm, between 50 µm and 600 µm, between 50 µm and 550 µm, between 50 µm and 500 µm, between 50 µm and 450 µm, between 50 µm and 400 µm, between50 µm and 350 µm, between 50 µm and 300 µm, between 50 µm and 250 µm, between 50 µm and 200 µm, between 50 µm and 150 µm, between 50 µm and 100 µm, between 100 µm and 1000 µm, between 150 µm and 1000 µm, between 200 µm and 1000 µm, between 250 µm and 1000 µm, between 300 µm and 1000 µm, between 350 µm and 1000 µm, between 400 µm and 1000 µm, between 450 µm and 1000 µm, between 500 µm and 1000 µm, between 550 µm and 1000 µm, between 600 µm and 1000 µm, between 650 µm and 1000 µm, between 700 µm and 1000 µm, between 750 µm and 1000 µm, between 800 µm and 1000 µm, between 850 µm and 1000 µm, between 900 µm and 1000 µm, between 950 µm and 1000 µm, between 100 µm and 950 µm, between 150 µm and 900 µm, between 200 µm and 850 µm, between 250 µm and 800 µm, between 300 µm and 750 µm, between 350 µm and 700 µm, between 400 µm and 650 µm, between 450 µm and 600 µm, between 500 µm and 550 µm, between 200 µm and 400 µm, between 210 µm and 390 µm, between 220 µm and 380 µm, between 230 µm and 370 µm, between 240 µm and 360 µm, between 250 µm and 350 µm, between 260 µm and 340 µm, between 270 µm and 330 µm, between 280 µm and 320 µm, or between 290 µm and 310 µm.

[0106] The GDL may have an average pore diameter of between 1 µm and 100 µm, between 1 µm and 90 µm, between 1 µm and 80 µm, between 1 µm and 70 µm, between 1 µm and 60 µm, between 1 µm and 50 µm, between 1 µm and 40 µm, between 1 µm and 30 µm, between 1 µm and 20 µm, or between 1 µm and 10 µm.

[0107] The GDL may have a porosity of between 50% and 95%, between 50% and 90%, between 50% and 85%, between 50% and 80%, between 50% and 75%, between 50% and 70%, between 50% and 65%, between 50% and 60%, between 50% and 55%, between 55% and 95%, between 60% and 95%, between 65% and 95%, between 70% and 95%, between 75% and 95%, between 80% and 95%, between 85% and 95%, between 90% and 95%.between 55% and 90%, between 60% and 85%, between 65% and 80%, or between 70% and 75%.

[0108] The GDL may comprise carbon-fibre paper, carbon cloth, carbon felt, carbon foam, metal mesh, metal foam, or any combination thereof. The GDL may be modified with a hydrophobic polymer treatment and / or application of a microporous layer (MPL).

[0109] Non-limiting examples of carbon-fibre paper include: (1a) Toray TGP-H carbon-fibre paper (e.g. TGP-H-030, TGP-H-060, TGP-H-090, TGP-H-120), (1b) AvCarb® carbon-fibre paper (e.g. MGL190, MGL280, MGL370, MGL190T, MGL280T, MGL370T, EP40, EP40T, EP55, EP55T, GDS1120, GDS2120, GDS22100, GDS2230, GDS2240, GDS3215, GDS3250, GDS3260, GDS5130, MB30, P50, P50T, P75, P75T), (1c) Spectracarb™ carbon-fibre paper (e.g. 2050A-0850, 2050A-1050, 2050A-1535, 2050A-1550, 2050A-1550 Treated), (1d) Freudenberg carbon-fibre paper (e.g. H14, H14C7, H14C9, H14C10, H14Cx653, H15, H15C13, H15C14, H23, H23C2, H23C3, H23C5, H23C6, H23C7, H23C8, H23C9, H23Cx653, H23I2), (1e) Sigracet® carbon-fibre paper (e.g.22 BB, 25 BA, 25 BC, 28 AA, 28 BC, 29 AA, 29 BC, 36 AA, 36BB, 39 AA, 39 BB), (1f) CeTech carbon-fibre paper (e.g. GDS180S, GDS210, GDS230, GDS 250, GDS310, GDL240, GDL280, GDL340, GDS090S, GDS180HT, GDL120, GDL210SHT), (1g) JNT carbon-fibre paper series (e.g. JNT15B, JNT17B, JNT18B, JNT20, JNT21, JNT30), (1h) LINQCELL carbon-fibre paper (e.g. GDP180, GDP210, GDP210-MP, GDP-210MPS, GDP 240, GDP340), and (1i) Mitsubishi Chemicals PYROFIL™ GDL.

[0110] Non-limiting examples of carbon cloth include: (2a) AvCarb® carbon cloth (e.g. 1071, 1698, 1209, 1185, 1186, 7497, T1819, T1820, T1824),(2b) E-TEK carbon cloth (e.g. CC4, CC4 Wet Proofed, CC6, CC6 Wet Proofed, ELAT plain cloth, ELAT LT1400, ELAT LT2400W), (2c) CeTech carbon cloth (e.g. W0S1009, W0S1011, W0S1011, W1S1011), (2d) Zoltek™ Panex carbon cloth (e.g. PW03, PW06, SW08), (2e) LINQCELL carbon cloth (e.g. CF350, CF400-MP), and (2f) SAATI SCCG carbon cloth (e.g. 5N).

[0111] Non-limiting examples of carbon felt include: (3a) AvCarb® felt (e.g. C100, C200, C280, G100, G200, G300A, G475A, G600A), (3b) CeTech felt (e.g. CF120, GF20, GF100), and (3c) JNT felt (e.g. GF051BH, GF061AH).

[0112] Non-limiting examples of the metal foam include: (4a) nickel foam, (4b) copper foam, (4c) titanium foam, (4d) silver foam, (4e) stainless steel foam, (4f) iron nickel foam, (4g) nickel copper foam, and (4h) cobalt foam.

[0113] Non-limiting examples of the metal mesh include: (5a) copper metal mesh,(5b) nickel metal mesh, (5c) titanium metal mesh, (5d) silver metal mesh, (5e) stainless steel metal mesh, and (5f) molybdenum metal mesh.

[0114] The skilled person, having regard to the present disclosure, will be well aware of other suitable materials and configurations of the GDL, including as described further herein. Hydrophobic polymeric treatment of GDL

[0115] In an embodiment, the GDL may be modified with a hydrophobic polymer. A GDL modified with a hydrophobic polymer treatment involves the application of a hydrophobic additive to the GDL to control the wettability of the GDL.

[0116] Non-limiting examples of such hydrophobic additives include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), fluorinated ethylene propylene (FEP), perfluoropolyether (PFPE), and polydimethylsiloxane (PDMS). The GDL may be modified with any one or any combination of hydrophobic additives.

[0117] The GDL may comprise no hydrophobic addition or between 0.01 wt% and 50 wt%, between 0.01 wt% and 45 wt%, between 0.01 wt% and 40 wt%, between 0.01 wt% and 35 wt%, between 0.01 wt% and 30 wt%, between 0.01 wt% and 25 wt%, between 0.01 wt% and 20 wt%, between 0.01 wt% and 15 wt%, between 0.01 wt% and 10 wt%, between 0.01 wt% and 5 wt%, between 5 wt% and 50 wt%, between 10 wt% and 50 wt%, between 15 wt% and 50 wt%, between 20 wt% and 50 wt%, between 25 wt% and 50 wt%, between 30 wt% and 50 wt%, between 35 wt% and 50 wt%, between 40 wt% and 50 wt%, between 45 wt% and 50 wt%, between 5 wt% and 45 wt%, between 10 wt% and 40 wt%, between 15 wt% and 35 wt%, between 20 wt% and 30 wt%, between 25 wt% and 45 wt%, or between 30 wt% and 40 wt% of the hydrophobic additive.Microporous Layer (MPL)

[0118] The MPL is disposed on the GDL and may aid with electrical conductivity and / or water management.

[0119] The MPL comprises a particulate material coated on a planar face of the GDL. Any suitable particular material may be used. In an embodiment, the particulate material may be a mixture of carbon black and a hydrophobic polymer such as polytetrafluoroethylene (PTFE).

[0120] The MPL may comprise between 50 wt% and 95 wt%, between 55 wt% and 95 wt%, between 60 wt% and 95 wt%, between 65 wt% and 95 wt%, between 70 wt% and 95 wt%, between 75 wt% and 95 wt%, between 80 wt% and 95 wt%, between 85 wt% and 95 wt%, between 90 wt% and 95 wt%, between 60 wt% and 90 wt%, between 60 wt% and 85 wt%, between 60 wt% and 80 wt%, between 60 wt% and 75 wt%, between 60 wt% and 70 wt%, between 60 wt% and 65 wt%, between 65 wt% and 90 wt%, between 70 wt% and 85 wt%, or between 75 wt% and 80 wt% of carbon black.

[0121] The MPL may comprise between 5 wt% and 50 wt%, between 5 wt% and 45 wt%, between 5 wt% and 40 wt%, between 5 wt% and 35 wt%, between 5 wt% and 30 wt%, between 5 wt% and 25 wt%, between 5 wt% and 20 wt%, between 5 wt% and 15 wt%, between 5 wt% and 10 wt%, between 10 wt% and 40 wt%, between 15 wt% and 40 wt%, between 20 wt% and 40 wt%, between 25 wt% and 40 wt%, between 30 wt% and 40 wt%, between 35 wt% and 40 wt%, between 10 wt% and 35 wt%, between 15 wt% and 30 wt%, or between 20 wt% and 25 wt% of the hydrophobic polymer.

[0122] The MPL may have a thickness of between 10 µm and 100 µm, between 10 µm and 90 µm, between 10 µm and 80 µm, between 10 µm and 70 µm, between 10 µm and 60 µm, between 10 µm and 50 µm, between 10 µm and 40 µm, between 10 µm and 30 µm, between 10 µm and 20 µm, between 20 µm and 100 µm, between 30 µm and 100 µm, between 40 µm and 100 µm, between 50 µm and 100 µm, between 60 µm and 100 µm, between 70 µm and 100 µm, between 80 µm and 100 µm, between 90 µm and 100 µm, between 20 µm and 90 µm, between 30 µm and 80 µm, between 40 µm and 70 µm, or between 50 µm and 60 µm.

[0123] The MPL may have an average pore diameter of between 0 µm and 10 µm, between 0 µm and 9 µm, between 0 µm and 8 µm, between 0 µm and 7 µm, between 0 µm and 6 µm, between 0 µm and 5 µm, between 0 µm and 4 µm, between 0 µm and 3 µm, between 0 µm and 2 µm, between 0 µm and 1 µm, between 0 µm and 0.9 µm, between 0 µm and 0.8 µm, between 0 µm and 0.7 µm, between 0 µm and 0.6 µm, between 0 µm and 0.5 µm, between 0 µm and 0.4 µm, between 0 µm and 0.3 µm, between 0 µm and 0.2 µm, or between 0 µm and 0.1 µm.

[0124] The MPL may have a porosity of between 30% to 75%, between 30% to 70%, between 30% to 65%, between 30% to 60%, between 30% to 55%, between 30% to 50%, between 30% to 55%, between 30% to 50%, between 30% to 45%, between 30% to 40%, between 30% to 35%, between 35% to 75%, between 40% to 75%, between 45% to 75%, between 50% to 75%, between 55% to 75%, between 60% to 75%, between 65% to 75%, or between 70% to 75%. Catalyst Layer (CL)

[0125] The catalyst layer may comprise a catalyst, and optionally an ionomer and / or a binder. In an embodiment, the catalyst layer may comprise a catalyst and an ionomer. In another embodiment, the catalyst layer may comprise a catalyst and a binder. In yet another embodiment, the catalyst layer may comprise a catalyst, an ionomer, and a binder. In still another embodiment, the GDE has only a single catalyst layer. In other embodiments, the GDE may comprise more than one catalyst layer.

[0126] The catalyst layer may be hydrophilic or hydrophobic, for example depending on the desired operation of the CL. In an embodiment, if the GDE comprises two CL, the first CL is hydrophilic and the second CL is hydrophobic. In other embodiments, both CLs may be hydrophobic or hydrophilic.

[0127] The catalyst layer may have a thickness of between 1 µm and 100 µm, between 1 µm and 95 µm, between 1 µm and 90 µm, between 1 µm and 85 µm, between 1 µm and 80 µm, between 1 µm and 75 µm, between 1 µm and 70 µm, between 1 µm and 65 µm, between 1 µm and 60 µm, between 1 µm and 55 µm, between 1 µm and 50 µm, between 1 µm and 45 µm, between 1 µm and 40 µm, between 1 µm and 35 µm, between 1 µm and 30 µm, between 1 µm and 25 µm, between 1 µm and 20 µm, between 1 µm and 15 µm, between 1 µm and 10 µm, between 1 µm and 9 µm, between 1 µm and 8 µm, between1 µm and 7 µm, between 1 µm and 6 µm, between 1 µm and 5 µm, between 1 µm and 4 µm, between 1 µm and 3 µm, or between 1 µm and 2 µm.

[0128] The catalyst layer may have a porosity of between 30% to 75%, between 30% to 70%, between 30% to 65%, between 30% to 60%, between 30% to 55%, between 30% to 50%, between 30% to 55%, between 30% to 50%, between 30% to 45%, between 30% to 40%, between 30% to 35%, between 35% to 75%, between 40% to 75%, between 45% to 75%, between 50% to 75%, between 55% to 75%, between 60% to 75%, between 65% to 75%, or between 70% to 75%.

[0129] The ionomer:catalyst ratio may be between 1:1 to 1:20, between 1:1 to 1:19, between 1:1 to 1:18, between 1:1 to 1:17, between 1:1 to 1:16, between 1:1 to 1:15, between 1:1 to 1:14, between 1:1 to 1:13, between 1:1 to 1:12, between 1:1 to 1:11, between 1:1 to 1:10, between 1:1 to 1:9, between 1:1 to 1:8, between 1:1 to 1:7, between 1:1 to 1:6, between 1:1 to 1:5, between 1:1 to 1:4, between 1:1 to 1:3, between 1:1 to 1:2, between 1:2 to 1:20, between 1:3 to 1:20, between 1:4 to 1:20, between 1:5 to 1:20, between 1:6 to 1:20, between 1:7 to 1:20, between 1:8 to 1:20, between 1:9 to 1:20, between 1:10 to 1:20, between 1:11 to 1:20, between 1:12 to 1:20, between 1:13 to 1:20, between 1:14 to 1:20, between 1:15 to 1:20, between 1:16 to 1:20, between 1:17 to 1:20, between 1:18 to 1:20, between 1:19 to 1:20, between 1:2 to 1:19, between 1:3 to 1:18, between 1:4 to 1:17, between 1:5 to 1:16, between 1:6 to 1:15, between 1:7 to 1:14, between 1:8 to 1:13, between 1:9 to 1:12, or between 1:10 to 1:11. Catalyst

[0130] The catalyst may include (6) a metal, (7) a non-metal, or a combination thereof.

[0131] The metal may be (6a) a transition metal, (6b) a post-transition metal, (6c) a metalloid, or a combination thereof, or an alloy thereof.

[0132] The catalyst including a transition metal may include: (6a-a) scandium (Sr), (6a-g) cobalt (Co), (6a-m) molybdenum (Mo), (6a-s) hafnium (Hf), (6a-b) titanium (Ti), (6a-h) nickel (Ni), (6a-n) ruthenium (Ru), (6a-t) tungsten (W), (6a-c) vanadium (V), (6a-i) copper (Cu), (6a-o) rhodium (Rh), (6a-u) iridium (Ir), (6a-d) chromium (Cr), (6a-j) zinc (Zn), (6a-p) palladium (Pd), (6a-v) platinum (Pt),(6a-e) manganese (Mn), (6a-k) yttrium (Y), (6a-q) silver (Ag), (6a-w) gold (Au), (6a-f) iron (Fe), (6a-l) zirconium (Zr), (6a-r) cadmium (Cd), or a combination thereof, or an alloy thereof. In a particular embodiment, the catalyst is platinum (6a-v), silver (6a-q), nickel (6a-h), or any combination thereof. In an embodiment, the catalyst is (6a-x) an alloy of platinum and nickel (PtNi). In an embodiment, the alloy comprises a weight ratio of platinum to nickel of between about 5:1 and about 1:5, more particularly between about 5:1 and 1:2, and more particularly still between about 3:1 and about 1:1. In an embodiment, the alloy comprises a weight ratio of platinum to nickel of about 5:1, 4.5:1, 4:1, 3.5:1, 3:1, 2.5:1, 2:1, 1.5:1, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, or 1:5.

[0133] The catalyst including a post-transition metal may include: (6b-a) aluminum (Al), (6b-c) indium (In), (6b-e) thallium (TI), (6b-g) bismuth (Bi), (6b-b) gallium (Ga), (6b-d) tin (Sn), (6b-f) lead (Pb), or a combination thereof, or an alloy thereof.

[0134] The catalyst including a metalloid may include: (6c-a) silicon (Si), (6c-b) germanium (Ge), (6c-c) antimony (Sb), (6c-d) telelium (Te), or a combination thereof.

[0135] The catalyst including a non-metal may include (7a) carbon, (7b) a conductive polymer, or a combination thereof.

[0136] The carbon refers to a material whose main component is composed of carbon atoms. For example, the carbon may be a carbon fiber, graphite, a carbon nanomaterial, or a combination thereof. The carbon nanomaterial may include a carbon nanotube, graphene, carbon nanoplate, or fullerene. Further, the material may optionally be doped with non-metallic elements (e.g. B, N, P, O or S).

[0137] The catalyst loading on the GDL may be between 0.1 and 10 mg cm-2, between 0.1 and 9.0 mg cm-2, between 0.1 and 8.0 mg cm-2, between 0.1 and 7.0 mg cm-2, between 0.1 and 6.0 mg cm-2, between 0.1 and 5.0 mg cm-2, between 0.1 and 4.0 mg cm-2, between 0.1 and 3.9 mg cm-2, between 0.1 and 3.8 mg cm-2, between 0.1 and 3.7 mg cm-2, between 0.1 and 3.6 mg cm-2, between 0.1 and 3.5 mg cm-2, between 0.1 and 3.4 mg cm-2, between 0.1 and 3.3 mg cm-2, between 0.1 and 3.2 mg cm-2, between 0.1 and 3.1 mg cm-2, between 0.1 and 3.0 mg cm-2, between 0.1 and 2.9 mg cm-2, between 0.1 and 2.8 mg cm-2,between 0.1 and 2.7 mg cm-2, between 0.1 and 2.6 mg cm-2, between 0.1 and 2.5 mg cm-2, between 0.1 and 2.4 mg cm-2, between 0.1 and 2.3 mg cm-2, between 0.1 and 2.2 mg cm-2, between 0.1 and 2.1 mg cm-2, between 0.1 and 2.0 mg cm-2, between 0.1 and 1.9 mg cm-2, between 0.1 and 1.8 mg cm-2, between 0.1 and 1.7 mg cm-2, between 0.1 and 1.6 mg cm-2, between 0.1 and 1.5 mg cm-2, between 0.1 and 1.4 mg cm-2, between 0.1 and 1.3 mg cm-2, between 0.1 and 1.2 mg cm-2, between 0.1 and 1.1 mg cm-2, between 0.1 and 1.0 mg cm-2, between 0.1 and 0.9 mg cm-2, between 0.1 and 0.8 mg cm-2, between 0.1 and 0.7 mg cm-2, between 0.1 and 0.6 mg cm-2, between 0.1 and 0.5 mg cm-2, between 0.1 and 0.4 mg cm-2, between 0.1 and 0.3 mg cm-2, or between 0.1 and 0.2 mg cm-2. Ionomer

[0138] The ionomer includes a polymer wherein at least a portion of the repeating units of the polymer comprise ionic groups (e.g., wherein the polymer is a copolymer comprising electrically neutral units and units comprising an ionic group).

[0139] In an embodiment, the ionomer comprises an anion exchange ionomer. The anion exchange ionomer includes ionomers where the ionic groups are preferably cationic groups, which promote conduction of anions via electrostatic interaction between the anions and cationic groups.

[0140] Non-limiting examples of the anion exchange ionomer (AEI) include (8a) FumionTMFAA-3 AEI, (8b) IonomrTMAEI (e.g. AF1, AF2, AF3, AP1, AP3), (8c) Sustainion® AEI (e.g. XA-9, XB-7, XC-1, XC-2), (8d) Orion AEI (e.g. TM1, AM, CMX), (8e) PentionTMAEI (e.g. D18, D35, D72), and (8f) PiperION AEI.

[0141] In an embodiment, the ionomer comprises a cation exchange ionomer. The cation exchange ionomer includes ionomers where the ionic groups are preferably anionic groups, which promote conduction of cations via electrostatic interaction between the anions and cationic groups.

[0142] Non-limiting examples of the cation exchange ionomer (CEI) include Aquivion® CEI (e.g. D72-25BS, D79-25BS, D83-24B, D98-25BS), FORBLUE™ i-SERIES CEI (e.g. IC100, IC154), FumionTMCEI (e.g. E-600, FSLA-102, FSLA-725), IonomrTMCEI (e.g. PP1), and NafionTMCEI (e.g. D520CS, D521CS, D2020CS, D2021CS).

[0143] The CL may comprise between 5 wt% and 45 wt%, between 5 wt% and 40 wt%, between 5 wt% and 35 wt%, between 5 wt% and 30 wt%, between 5 wt% and 25 wt%, between 5 wt% and 20 wt%, between 5 wt% and 15 wt%, between 5 wt% and 10 wt%, between 10 wt% and 45 wt%, between 15 wt% and 45 wt%, between 20 wt% and 45 wt%, between 25 wt% and 45 wt%, between 30 wt% and 45 wt%, between 35 wt% and 45 wt%, between 40 wt% and 45 wt%, between 10 wt% and 40 wt%, between 15 wt% and 35 wt%, or between 20 wt% and 30 wt% of the ionomer. Binder

[0144] In an embodiment, the CL comprises a binder. The binder may, for example, be a polymer that is hydrophilic or hydrophobic. Non-limiting examples of the binder include (9a) PTFE.

[0145] The CL may comprise no binder or, if present, between 0.01 wt% and 40 wt%, between 0.01 wt% and 35 wt%, between 0.01 wt% and 30 wt%, between 0.01 wt% and 25 wt%, between 0.01 wt% and 20 wt%, between 0.01 wt% and 15 wt%, between 0.01 wt% and 10 wt%, between 0.01 wt% and 5 wt%, between 5 wt% and 40 wt%, between 10 wt% and 40 wt%, between 15 wt% and 40 wt%, between 20 wt% and 40 wt%, between 25 wt% and 40 wt%, between 30 wt% and 40 wt%, between 35 wt% and 40 wt%, between 5 wt% and 35 wt%, between 10 wt% and 30 wt%, or between 15 wt% and 25 wt% of the binder.

[0146] Various particular embodiments of GDEs of the present disclosure include GDEs described herein as GDE-1, GDE-2, GDE-3 or GDE-4, each having components as defined in the following rows, wherein each entry is a group number as defined above: GDE Embodiment GDL Catalyst Ionomer Binder 1 (1a) (6a-h) (8a) (9a) 2 (1b) (6a-h) (8a) (9a) 3 (1c) (6a-h) (8a) (9a) 4 (1d) (6a-h) (8a) (9a) 5 (1e) (6a-h) (8a) (9a) 6 (1f) (6a-h) (8a) (9a) 7 (1g) (6a-h) (8a) (9a) 8 (1h) (6a-h) (8a) (9a) 9 (1i) (6a-h) (8a) (9a) 10 (2a) (6a-h) (8a) (9a)GDE Embodiment GDL Catalyst Ionomer Binder 11 (2b) (6a-h) (8a) (9a) 12 (2c) (6a-h) (8a) (9a) 13 (2d) (6a-h) (8a) (9a) 14 (2e) (6a-h) (8a) (9a) 15 (2f) (6a-h) (8a) (9a) 16 (3a) (6a-h) (8a) (9a) 17 (3b) (6a-h) (8a) (9a) 18 (3c) (6a-h) (8a) (9a) 19 (4a) (6a-h) (8a) (9a) 20 (4b) (6a-h) (8a) (9a) 21 (4c) (6a-h) (8a) (9a) 22 (4d) (6a-h) (8a) (9a) 23 (4e) (6a-h) (8a) (9a) 24 (4f) (6a-h) (8a) (9a) 25 (4g) (6a-h) (8a) (9a) 26 (4h) (6a-h) (8a) (9a) 27 (5a) (6a-h) (8a) (9a) 28 (5b) (6a-h) (8a) (9a) 29 (5c) (6a-h) (8a) (9a) 30 (5d) (6a-h) (8a) (9a) 31 (5e) (6a-h) (8a) (9a) 32 (5f) (6a-h) (8a) (9a) 33 (1a) (6a-h) (8b) (9a) 34 (1b) (6a-h) (8b) (9a) 35 (1c) (6a-h) (8b) (9a) 36 (1d) (6a-h) (8b) (9a) 37 (1e) (6a-h) (8b) (9a) 38 (1f) (6a-h) (8b) (9a) 39 (1g) (6a-h) (8b) (9a) 40 (1h) (6a-h) (8b) (9a) 41 (1i) (6a-h) (8b) (9a) 42 (2a) (6a-h) (8b) (9a) 43 (2b) (6a-h) (8b) (9a) 44 (2c) (6a-h) (8b) (9a) 45 (2d) (6a-h) (8b) (9a) 46 (2e) (6a-h) (8b) (9a) 47 (2f) (6a-h) (8b) (9a) 48 (3a) (6a-h) (8b) (9a) 49 (3b) (6a-h) (8b) (9a) 50 (3c) (6a-h) (8b) (9a)GDE Embodiment GDL Catalyst Ionomer Binder 51 (4a) (6a-h) (8b) (9a) 52 (4b) (6a-h) (8b) (9a) 53 (4c) (6a-h) (8b) (9a) 54 (4d) (6a-h) (8b) (9a) 55 (4e) (6a-h) (8b) (9a) 56 (4f) (6a-h) (8b) (9a) 57 (4g) (6a-h) (8b) (9a) 58 (4h) (6a-h) (8b) (9a) 59 (5a) (6a-h) (8b) (9a) 60 (5b) (6a-h) (8b) (9a) 61 (5c) (6a-h) (8b) (9a) 62 (5d) (6a-h) (8b) (9a) 63 (5e) (6a-h) (8b) (9a) 64 (5f) (6a-h) (8b) (9a) 65 (1a) (6a-h) (8c) (9a) 66 (1b) (6a-h) (8c) (9a) 67 (1c) (6a-h) (8c) (9a) 68 (1d) (6a-h) (8c) (9a) 69 (1e) (6a-h) (8c) (9a) 70 (1f) (6a-h) (8c) (9a) 71 (1g) (6a-h) (8c) (9a) 72 (1h) (6a-h) (8c) (9a) 73 (1i) (6a-h) (8c) (9a) 74 (2a) (6a-h) (8c) (9a) 75 (2b) (6a-h) (8c) (9a) 76 (2c) (6a-h) (8c) (9a) 77 (2d) (6a-h) (8c) (9a) 78 (2e) (6a-h) (8c) (9a) 79 (2f) (6a-h) (8c) (9a) 80 (3a) (6a-h) (8c) (9a) 81 (3b) (6a-h) (8c) (9a) 82 (3c) (6a-h) (8c) (9a) 83 (4a) (6a-h) (8c) (9a) 84 (4b) (6a-h) (8c) (9a) 85 (4c) (6a-h) (8c) (9a) 86 (4d) (6a-h) (8c) (9a) 87 (4e) (6a-h) (8c) (9a) 88 (4f) (6a-h) (8c) (9a) 89 (4g) (6a-h) (8c) (9a) 90 (4h) (6a-h) (8c) (9a)GDE Embodiment GDL Catalyst Ionomer Binder 91 (5a) (6a-h) (8c) (9a) 92 (5b) (6a-h) (8c) (9a) 93 (5c) (6a-h) (8c) (9a) 94 (5d) (6a-h) (8c) (9a) 95 (5e) (6a-h) (8c) (9a) 96 (5f) (6a-h) (8c) (9a) 97 (1a) (6a-h) (8d) (9a) 98 (1b) (6a-h) (8d) (9a) 99 (1c) (6a-h) (8d) (9a) 100 (1d) (6a-h) (8d) (9a) 101 (1e) (6a-h) (8d) (9a) 102 (1f) (6a-h) (8d) (9a) 103 (1g) (6a-h) (8d) (9a) 104 (1h) (6a-h) (8d) (9a) 105 (1i) (6a-h) (8d) (9a) 106 (2a) (6a-h) (8d) (9a) 107 (2b) (6a-h) (8d) (9a) 108 (2c) (6a-h) (8d) (9a) 109 (2d) (6a-h) (8d) (9a) 110 (2e) (6a-h) (8d) (9a) 111 (2f) (6a-h) (8d) (9a) 112 (3a) (6a-h) (8d) (9a) 113 (3b) (6a-h) (8d) (9a) 114 (3c) (6a-h) (8d) (9a) 115 (4a) (6a-h) (8d) (9a) 116 (4b) (6a-h) (8d) (9a) 117 (4c) (6a-h) (8d) (9a) 118 (4d) (6a-h) (8d) (9a) 119 (4e) (6a-h) (8d) (9a) 120 (4f) (6a-h) (8d) (9a) 121 (4g) (6a-h) (8d) (9a) 122 (4h) (6a-h) (8d) (9a) 123 (5a) (6a-h) (8d) (9a) 124 (5b) (6a-h) (8d) (9a) 125 (5c) (6a-h) (8d) (9a) 126 (5d) (6a-h) (8d) (9a) 127 (5e) (6a-h) (8d) (9a) 128 (5f) (6a-h) (8d) (9a) 129 (1a) (6a-n) (8a) (9a) 130 (1b) (6a-n) (8a) (9a)GDE Embodiment GDL Catalyst Ionomer Binder 131 (1c) (6a-n) (8a) (9a) 132 (1d) (6a-n) (8a) (9a) 133 (1e) (6a-n) (8a) (9a) 134 (1f) (6a-n) (8a) (9a) 135 (1g) (6a-n) (8a) (9a) 136 (1h) (6a-n) (8a) (9a) 137 (1i) (6a-n) (8a) (9a) 138 (2a) (6a-n) (8a) (9a) 139 (2b) (6a-n) (8a) (9a) 140 (2c) (6a-n) (8a) (9a) 141 (2d) (6a-n) (8a) (9a) 142 (2e) (6a-n) (8a) (9a) 143 (2f) (6a-n) (8a) (9a) 144 (3a) (6a-n) (8a) (9a) 145 (3b) (6a-n) (8a) (9a) 146 (3c) (6a-n) (8a) (9a) 147 (4a) (6a-n) (8a) (9a) 148 (4b) (6a-n) (8a) (9a) 149 (4c) (6a-n) (8a) (9a) 150 (4d) (6a-n) (8a) (9a) 151 (4e) (6a-n) (8a) (9a) 152 (4f) (6a-n) (8a) (9a) 153 (4g) (6a-n) (8a) (9a) 154 (4h) (6a-n) (8a) (9a) 155 (5a) (6a-n) (8a) (9a) 156 (5b) (6a-n) (8a) (9a) 157 (5c) (6a-n) (8a) (9a) 158 (5d) (6a-n) (8a) (9a) 159 (5e) (6a-n) (8a) (9a) 160 (5f) (6a-n) (8a) (9a) 161 (1a) (6a-n) (8b) (9a) 162 (1b) (6a-n) (8b) (9a) 163 (1c) (6a-n) (8b) (9a) 164 (1d) (6a-n) (8b) (9a) 165 (1e) (6a-n) (8b) (9a) 166 (1f) (6a-n) (8b) (9a) 167 (1g) (6a-n) (8b) (9a) 168 (1h) (6a-n) (8b) (9a) 169 (1i) (6a-n) (8b) (9a) 170 (2a) (6a-n) (8b) (9a)GDE Embodiment GDL Catalyst Ionomer Binder 171 (2b) (6a-n) (8b) (9a) 172 (2c) (6a-n) (8b) (9a) 173 (2d) (6a-n) (8b) (9a) 174 (2e) (6a-n) (8b) (9a) 175 (2f) (6a-n) (8b) (9a) 176 (3a) (6a-n) (8b) (9a) 177 (3b) (6a-n) (8b) (9a) 178 (3c) (6a-n) (8b) (9a) 179 (4a) (6a-n) (8b) (9a) 180 (4b) (6a-n) (8b) (9a) 181 (4c) (6a-n) (8b) (9a) 182 (4d) (6a-n) (8b) (9a) 183 (4e) (6a-n) (8b) (9a) 184 (4f) (6a-n) (8b) (9a) 185 (4g) (6a-n) (8b) (9a) 186 (4h) (6a-n) (8b) (9a) 187 (5a) (6a-n) (8b) (9a) 188 (5b) (6a-n) (8b) (9a) 189 (5c) (6a-n) (8b) (9a) 190 (5d) (6a-n) (8b) (9a) 191 (5e) (6a-n) (8b) (9a) 192 (5f) (6a-n) (8b) (9a) 193 (1a) (6a-n) (8c) (9a) 194 (1b) (6a-n) (8c) (9a) 195 (1c) (6a-n) (8c) (9a) 196 (1d) (6a-n) (8c) (9a) 197 (1e) (6a-n) (8c) (9a) 198 (1f) (6a-n) (8c) (9a) 199 (1g) (6a-n) (8c) (9a) 200 (1h) (6a-n) (8c) (9a) 201 (1i) (6a-n) (8c) (9a) 202 (2a) (6a-n) (8c) (9a) 203 (2b) (6a-n) (8c) (9a) 204 (2c) (6a-n) (8c) (9a) 205 (2d) (6a-n) (8c) (9a) 206 (2e) (6a-n) (8c) (9a) 207 (2f) (6a-n) (8c) (9a) 208 (3a) (6a-n) (8c) (9a) 209 (3b) (6a-n) (8c) (9a) 210 (3c) (6a-n) (8c) (9a)GDE Embodiment GDL Catalyst Ionomer Binder 211 (4a) (6a-n) (8c) (9a) 212 (4b) (6a-n) (8c) (9a) 213 (4c) (6a-n) (8c) (9a) 214 (4d) (6a-n) (8c) (9a) 215 (4e) (6a-n) (8c) (9a) 216 (4f) (6a-n) (8c) (9a) 217 (4g) (6a-n) (8c) (9a) 218 (4h) (6a-n) (8c) (9a) 219 (5a) (6a-n) (8c) (9a) 220 (5b) (6a-n) (8c) (9a) 221 (5c) (6a-n) (8c) (9a) 222 (5d) (6a-n) (8c) (9a) 223 (5e) (6a-n) (8c) (9a) 224 (5f) (6a-n) (8c) (9a) 225 (1a) (6a-n) (8d) (9a) 226 (1b) (6a-n) (8d) (9a) 227 (1c) (6a-n) (8d) (9a) 228 (1d) (6a-n) (8d) (9a) 229 (1e) (6a-n) (8d) (9a) 230 (1f) (6a-n) (8d) (9a) 231 (1g) (6a-n) (8d) (9a) 232 (1h) (6a-n) (8d) (9a) 233 (1i) (6a-n) (8d) (9a) 234 (2a) (6a-n) (8d) (9a) 235 (2b) (6a-n) (8d) (9a) 236 (2c) (6a-n) (8d) (9a) 237 (2d) (6a-n) (8d) (9a) 238 (2e) (6a-n) (8d) (9a) 239 (2f) (6a-n) (8d) (9a) 240 (3a) (6a-n) (8d) (9a) 241 (3b) (6a-n) (8d) (9a) 242 (3c) (6a-n) (8d) (9a) 243 (4a) (6a-n) (8d) (9a) 244 (4b) (6a-n) (8d) (9a) 245 (4c) (6a-n) (8d) (9a) 246 (4d) (6a-n) (8d) (9a) 247 (4e) (6a-n) (8d) (9a) 248 (4f) (6a-n) (8d) (9a) 249 (4g) (6a-n) (8d) (9a) 250 (4h) (6a-n) (8d) (9a)GDE Embodiment GDL Catalyst Ionomer Binder 251 (5a) (6a-n) (8d) (9a) 252 (5b) (6a-n) (8d) (9a) 253 (5c) (6a-n) (8d) (9a) 254 (5d) (6a-n) (8d) (9a) 255 (5e) (6a-n) (8d) (9a) 256 (5f) (6a-n) (8d) (9a) 257 (1a) (6a-p) (8a) (9a) 258 (1b) (6a-p) (8a) (9a) 259 (1c) (6a-p) (8a) (9a) 260 (1d) (6a-p) (8a) (9a) 261 (1e) (6a-p) (8a) (9a) 262 (1f) (6a-p) (8a) (9a) 263 (1g) (6a-p) (8a) (9a) 264 (1h) (6a-p) (8a) (9a) 265 (1i) (6a-p) (8a) (9a) 266 (2a) (6a-p) (8a) (9a) 267 (2b) (6a-p) (8a) (9a) 268 (2c) (6a-p) (8a) (9a) 269 (2d) (6a-p) (8a) (9a) 270 (2e) (6a-p) (8a) (9a) 271 (2f) (6a-p) (8a) (9a) 272 (3a) (6a-p) (8a) (9a) 273 (3b) (6a-p) (8a) (9a) 274 (3c) (6a-p) (8a) (9a) 275 (4a) (6a-p) (8a) (9a) 276 (4b) (6a-p) (8a) (9a) 277 (4c) (6a-p) (8a) (9a) 278 (4d) (6a-p) (8a) (9a) 279 (4e) (6a-p) (8a) (9a) 280 (4f) (6a-p) (8a) (9a) 281 (4g) (6a-p) (8a) (9a) 282 (4h) (6a-p) (8a) (9a) 283 (5a) (6a-p) (8a) (9a) 284 (5b) (6a-p) (8a) (9a) 285 (5c) (6a-p) (8a) (9a) 286 (5d) (6a-p) (8a) (9a) 287 (5e) (6a-p) (8a) (9a) 288 (5f) (6a-p) (8a) (9a) 289 (1a) (6a-p) (8b) (9a) 290 (1b) (6a-p) (8b) (9a)GDE Embodiment GDL Catalyst Ionomer Binder 291 (1c) (6a-p) (8b) (9a) 292 (1d) (6a-p) (8b) (9a) 293 (1e) (6a-p) (8b) (9a) 294 (1f) (6a-p) (8b) (9a) 295 (1g) (6a-p) (8b) (9a) 296 (1h) (6a-p) (8b) (9a) 297 (1i) (6a-p) (8b) (9a) 298 (2a) (6a-p) (8b) (9a) 299 (2b) (6a-p) (8b) (9a) 300 (2c) (6a-p) (8b) (9a) 301 (2d) (6a-p) (8b) (9a) 302 (2e) (6a-p) (8b) (9a) 303 (2f) (6a-p) (8b) (9a) 304 (3a) (6a-p) (8b) (9a) 305 (3b) (6a-p) (8b) (9a) 306 (3c) (6a-p) (8b) (9a) 307 (4a) (6a-p) (8b) (9a) 308 (4b) (6a-p) (8b) (9a) 309 (4c) (6a-p) (8b) (9a) 310 (4d) (6a-p) (8b) (9a) 311 (4e) (6a-p) (8b) (9a) 312 (4f) (6a-p) (8b) (9a) 313 (4g) (6a-p) (8b) (9a) 314 (4h) (6a-p) (8b) (9a) 315 (5a) (6a-p) (8b) (9a) 316 (5b) (6a-p) (8b) (9a) 317 (5c) (6a-p) (8b) (9a) 318 (5d) (6a-p) (8b) (9a) 319 (5e) (6a-p) (8b) (9a) 320 (5f) (6a-p) (8b) (9a) 321 (1a) (6a-p) (8c) (9a) 322 (1b) (6a-p) (8c) (9a) 323 (1c) (6a-p) (8c) (9a) 324 (1d) (6a-p) (8c) (9a) 325 (1e) (6a-p) (8c) (9a) 326 (1f) (6a-p) (8c) (9a) 327 (1g) (6a-p) (8c) (9a) 328 (1h) (6a-p) (8c) (9a) 329 (1i) (6a-p) (8c) (9a) 330 (2a) (6a-p) (8c) (9a)GDE Embodiment GDL Catalyst Ionomer Binder 331 (2b) (6a-p) (8c) (9a) 332 (2c) (6a-p) (8c) (9a) 333 (2d) (6a-p) (8c) (9a) 334 (2e) (6a-p) (8c) (9a) 335 (2f) (6a-p) (8c) (9a) 336 (3a) (6a-p) (8c) (9a) 337 (3b) (6a-p) (8c) (9a) 338 (3c) (6a-p) (8c) (9a) 339 (4a) (6a-p) (8c) (9a) 340 (4b) (6a-p) (8c) (9a) 341 (4c) (6a-p) (8c) (9a) 342 (4d) (6a-p) (8c) (9a) 343 (4e) (6a-p) (8c) (9a) 344 (4f) (6a-p) (8c) (9a) 345 (4g) (6a-p) (8c) (9a) 346 (4h) (6a-p) (8c) (9a) 347 (5a) (6a-p) (8c) (9a) 348 (5b) (6a-p) (8c) (9a) 349 (5c) (6a-p) (8c) (9a) 350 (5d) (6a-p) (8c) (9a) 351 (5e) (6a-p) (8c) (9a) 352 (5f) (6a-p) (8c) (9a) 353 (1a) (6a-p) (8d) (9a) 354 (1b) (6a-p) (8d) (9a) 355 (1c) (6a-p) (8d) (9a) 356 (1d) (6a-p) (8d) (9a) 357 (1e) (6a-p) (8d) (9a) 358 (1f) (6a-p) (8d) (9a) 359 (1g) (6a-p) (8d) (9a) 360 (1h) (6a-p) (8d) (9a) 361 (1i) (6a-p) (8d) (9a) 362 (2a) (6a-p) (8d) (9a) 363 (2b) (6a-p) (8d) (9a) 364 (2c) (6a-p) (8d) (9a) 365 (2d) (6a-p) (8d) (9a) 366 (2e) (6a-p) (8d) (9a) 367 (2f) (6a-p) (8d) (9a) 368 (3a) (6a-p) (8d) (9a) 369 (3b) (6a-p) (8d) (9a) 370 (3c) (6a-p) (8d) (9a)GDE Embodiment GDL Catalyst Ionomer Binder 371 (4a) (6a-p) (8d) (9a) 372 (4b) (6a-p) (8d) (9a) 373 (4c) (6a-p) (8d) (9a) 374 (4d) (6a-p) (8d) (9a) 375 (4e) (6a-p) (8d) (9a) 376 (4f) (6a-p) (8d) (9a) 377 (4g) (6a-p) (8d) (9a) 378 (4h) (6a-p) (8d) (9a) 379 (5a) (6a-p) (8d) (9a) 380 (5b) (6a-p) (8d) (9a) 381 (5c) (6a-p) (8d) (9a) 382 (5d) (6a-p) (8d) (9a) 383 (5e) (6a-p) (8d) (9a) 384 (5f) (6a-p) (8d) (9a) 385 (1a) (6a-q) (8a) (9a) 386 (1b) (6a-q) (8a) (9a) 387 (1c) (6a-q) (8a) (9a) 388 (1d) (6a-q) (8a) (9a) 389 (1e) (6a-q) (8a) (9a) 390 (1f) (6a-q) (8a) (9a) 391 (1g) (6a-q) (8a) (9a) 392 (1h) (6a-q) (8a) (9a) 393 (1i) (6a-q) (8a) (9a) 394 (2a) (6a-q) (8a) (9a) 395 (2b) (6a-q) (8a) (9a) 396 (2c) (6a-q) (8a) (9a) 397 (2d) (6a-q) (8a) (9a) 398 (2e) (6a-q) (8a) (9a) 399 (2f) (6a-q) (8a) (9a) 400 (3a) (6a-q) (8a) (9a) 401 (3b) (6a-q) (8a) (9a) 402 (3c) (6a-q) (8a) (9a) 403 (4a) (6a-q) (8a) (9a) 404 (4b) (6a-q) (8a) (9a) 405 (4c) (6a-q) (8a) (9a) 406 (4d) (6a-q) (8a) (9a) 407 (4e) (6a-q) (8a) (9a) 408 (4f) (6a-q) (8a) (9a) 409 (4g) (6a-q) (8a) (9a) 410 (4h) (6a-q) (8a) (9a)GDE Embodiment GDL Catalyst Ionomer Binder 411 (5a) (6a-q) (8a) (9a) 412 (5b) (6a-q) (8a) (9a) 413 (5c) (6a-q) (8a) (9a) 414 (5d) (6a-q) (8a) (9a) 415 (5e) (6a-q) (8a) (9a) 416 (5f) (6a-q) (8a) (9a) 417 (1a) (6a-q) (8b) (9a) 418 (1b) (6a-q) (8b) (9a) 419 (1c) (6a-q) (8b) (9a) 420 (1d) (6a-q) (8b) (9a) 421 (1e) (6a-q) (8b) (9a) 422 (1f) (6a-q) (8b) (9a) 423 (1g) (6a-q) (8b) (9a) 424 (1h) (6a-q) (8b) (9a) 425 (1i) (6a-q) (8b) (9a) 426 (2a) (6a-q) (8b) (9a) 427 (2b) (6a-q) (8b) (9a) 428 (2c) (6a-q) (8b) (9a) 429 (2d) (6a-q) (8b) (9a) 430 (2e) (6a-q) (8b) (9a) 431 (2f) (6a-q) (8b) (9a) 432 (3a) (6a-q) (8b) (9a) 433 (3b) (6a-q) (8b) (9a) 434 (3c) (6a-q) (8b) (9a) 435 (4a) (6a-q) (8b) (9a) 436 (4b) (6a-q) (8b) (9a) 437 (4c) (6a-q) (8b) (9a) 438 (4d) (6a-q) (8b) (9a) 439 (4e) (6a-q) (8b) (9a) 440 (4f) (6a-q) (8b) (9a) 441 (4g) (6a-q) (8b) (9a) 442 (4h) (6a-q) (8b) (9a) 443 (5a) (6a-q) (8b) (9a) 444 (5b) (6a-q) (8b) (9a) 445 (5c) (6a-q) (8b) (9a) 446 (5d) (6a-q) (8b) (9a) 447 (5e) (6a-q) (8b) (9a) 448 (5f) (6a-q) (8b) (9a) 449 (1a) (6a-q) (8c) (9a) 450 (1b) (6a-q) (8c) (9a)GDE Embodiment GDL Catalyst Ionomer Binder 451 (1c) (6a-q) (8c) (9a) 452 (1d) (6a-q) (8c) (9a) 453 (1e) (6a-q) (8c) (9a) 454 (1f) (6a-q) (8c) (9a) 455 (1g) (6a-q) (8c) (9a) 456 (1h) (6a-q) (8c) (9a) 457 (1i) (6a-q) (8c) (9a) 458 (2a) (6a-q) (8c) (9a) 459 (2b) (6a-q) (8c) (9a) 460 (2c) (6a-q) (8c) (9a) 461 (2d) (6a-q) (8c) (9a) 462 (2e) (6a-q) (8c) (9a) 463 (2f) (6a-q) (8c) (9a) 464 (3a) (6a-q) (8c) (9a) 465 (3b) (6a-q) (8c) (9a) 466 (3c) (6a-q) (8c) (9a) 467 (4a) (6a-q) (8c) (9a) 468 (4b) (6a-q) (8c) (9a) 469 (4c) (6a-q) (8c) (9a) 470 (4d) (6a-q) (8c) (9a) 471 (4e) (6a-q) (8c) (9a) 472 (4f) (6a-q) (8c) (9a) 473 (4g) (6a-q) (8c) (9a) 474 (4h) (6a-q) (8c) (9a) 475 (5a) (6a-q) (8c) (9a) 476 (5b) (6a-q) (8c) (9a) 477 (5c) (6a-q) (8c) (9a) 478 (5d) (6a-q) (8c) (9a) 479 (5e) (6a-q) (8c) (9a) 480 (5f) (6a-q) (8c) (9a) 481 (1a) (6a-q) (8d) (9a) 482 (1b) (6a-q) (8d) (9a) 483 (1c) (6a-q) (8d) (9a) 484 (1d) (6a-q) (8d) (9a) 485 (1e) (6a-q) (8d) (9a) 486 (1f) (6a-q) (8d) (9a) 487 (1g) (6a-q) (8d) (9a) 488 (1h) (6a-q) (8d) (9a) 489 (1i) (6a-q) (8d) (9a) 490 (2a) (6a-q) (8d) (9a)GDE Embodiment GDL Catalyst Ionomer Binder 491 (2b) (6a-q) (8d) (9a) 492 (2c) (6a-q) (8d) (9a) 493 (2d) (6a-q) (8d) (9a) 494 (2e) (6a-q) (8d) (9a) 495 (2f) (6a-q) (8d) (9a) 496 (3a) (6a-q) (8d) (9a) 497 (3b) (6a-q) (8d) (9a) 498 (3c) (6a-q) (8d) (9a) 499 (4a) (6a-q) (8d) (9a) 500 (4b) (6a-q) (8d) (9a) 501 (4c) (6a-q) (8d) (9a) 502 (4d) (6a-q) (8d) (9a) 503 (4e) (6a-q) (8d) (9a) 504 (4f) (6a-q) (8d) (9a) 505 (4g) (6a-q) (8d) (9a) 506 (4h) (6a-q) (8d) (9a) 507 (5a) (6a-q) (8d) (9a) 508 (5b) (6a-q) (8d) (9a) 509 (5c) (6a-q) (8d) (9a) 510 (5d) (6a-q) (8d) (9a) 511 (5e) (6a-q) (8d) (9a) 512 (5f) (6a-q) (8d) (9a) 513 (1a) (6a-v) (8a) (9a) 514 (1b) (6a-v) (8a) (9a) 515 (1c) (6a-v) (8a) (9a) 516 (1d) (6a-v) (8a) (9a) 517 (1e) (6a-v) (8a) (9a) 518 (1f) (6a-v) (8a) (9a) 519 (1g) (6a-v) (8a) (9a) 520 (1h) (6a-v) (8a) (9a) 521 (1i) (6a-v) (8a) (9a) 522 (2a) (6a-v) (8a) (9a) 523 (2b) (6a-v) (8a) (9a) 524 (2c) (6a-v) (8a) (9a) 525 (2d) (6a-v) (8a) (9a) 526 (2e) (6a-v) (8a) (9a) 527 (2f) (6a-v) (8a) (9a) 528 (3a) (6a-v) (8a) (9a) 529 (3b) (6a-v) (8a) (9a) 530 (3c) (6a-v) (8a) (9a)GDE Embodiment GDL Catalyst Ionomer Binder 531 (4a) (6a-v) (8a) (9a) 532 (4b) (6a-v) (8a) (9a) 533 (4c) (6a-v) (8a) (9a) 534 (4d) (6a-v) (8a) (9a) 535 (4e) (6a-v) (8a) (9a) 536 (4f) (6a-v) (8a) (9a) 537 (4g) (6a-v) (8a) (9a) 538 (4h) (6a-v) (8a) (9a) 539 (5a) (6a-v) (8a) (9a) 540 (5b) (6a-v) (8a) (9a) 541 (5c) (6a-v) (8a) (9a) 542 (5d) (6a-v) (8a) (9a) 543 (5e) (6a-v) (8a) (9a) 544 (5f) (6a-v) (8a) (9a) 545 (1a) (6a-v) (8b) (9a) 546 (1b) (6a-v) (8b) (9a) 547 (1c) (6a-v) (8b) (9a) 548 (1d) (6a-v) (8b) (9a) 549 (1e) (6a-v) (8b) (9a) 550 (1f) (6a-v) (8b) (9a) 551 (1g) (6a-v) (8b) (9a) 552 (1h) (6a-v) (8b) (9a) 553 (1i) (6a-v) (8b) (9a) 554 (2a) (6a-v) (8b) (9a) 555 (2b) (6a-v) (8b) (9a) 556 (2c) (6a-v) (8b) (9a) 557 (2d) (6a-v) (8b) (9a) 558 (2e) (6a-v) (8b) (9a) 559 (2f) (6a-v) (8b) (9a) 560 (3a) (6a-v) (8b) (9a) 561 (3b) (6a-v) (8b) (9a) 562 (3c) (6a-v) (8b) (9a) 563 (4a) (6a-v) (8b) (9a) 564 (4b) (6a-v) (8b) (9a) 565 (4c) (6a-v) (8b) (9a) 566 (4d) (6a-v) (8b) (9a) 567 (4e) (6a-v) (8b) (9a) 568 (4f) (6a-v) (8b) (9a) 569 (4g) (6a-v) (8b) (9a) 570 (4h) (6a-v) (8b) (9a)GDE Embodiment GDL Catalyst Ionomer Binder 571 (5a) (6a-v) (8b) (9a) 572 (5b) (6a-v) (8b) (9a) 573 (5c) (6a-v) (8b) (9a) 574 (5d) (6a-v) (8b) (9a) 575 (5e) (6a-v) (8b) (9a) 576 (5f) (6a-v) (8b) (9a) 577 (1a) (6a-v) (8c) (9a) 578 (1b) (6a-v) (8c) (9a) 579 (1c) (6a-v) (8c) (9a) 580 (1d) (6a-v) (8c) (9a) 581 (1e) (6a-v) (8c) (9a) 582 (1f) (6a-v) (8c) (9a) 583 (1g) (6a-v) (8c) (9a) 584 (1h) (6a-v) (8c) (9a) 585 (1i) (6a-v) (8c) (9a) 586 (2a) (6a-v) (8c) (9a) 587 (2b) (6a-v) (8c) (9a) 588 (2c) (6a-v) (8c) (9a) 589 (2d) (6a-v) (8c) (9a) 590 (2e) (6a-v) (8c) (9a) 591 (2f) (6a-v) (8c) (9a) 592 (3a) (6a-v) (8c) (9a) 593 (3b) (6a-v) (8c) (9a) 594 (3c) (6a-v) (8c) (9a) 595 (4a) (6a-v) (8c) (9a) 596 (4b) (6a-v) (8c) (9a) 597 (4c) (6a-v) (8c) (9a) 598 (4d) (6a-v) (8c) (9a) 599 (4e) (6a-v) (8c) (9a) 600 (4f) (6a-v) (8c) (9a) 601 (4g) (6a-v) (8c) (9a) 602 (4h) (6a-v) (8c) (9a) 603 (5a) (6a-v) (8c) (9a) 604 (5b) (6a-v) (8c) (9a) 605 (5c) (6a-v) (8c) (9a) 606 (5d) (6a-v) (8c) (9a) 607 (5e) (6a-v) (8c) (9a) 608 (5f) (6a-v) (8c) (9a) 609 (1a) (6a-v) (8d) (9a) 610 (1b) (6a-v) (8d) (9a)GDE Embodiment GDL Catalyst Ionomer Binder 611 (1c) (6a-v) (8d) (9a) 612 (1d) (6a-v) (8d) (9a) 613 (1e) (6a-v) (8d) (9a) 614 (1f) (6a-v) (8d) (9a) 615 (1g) (6a-v) (8d) (9a) 616 (1h) (6a-v) (8d) (9a) 617 (1i) (6a-v) (8d) (9a) 618 (2a) (6a-v) (8d) (9a) 619 (2b) (6a-v) (8d) (9a) 620 (2c) (6a-v) (8d) (9a) 621 (2d) (6a-v) (8d) (9a) 622 (2e) (6a-v) (8d) (9a) 623 (2f) (6a-v) (8d) (9a) 624 (3a) (6a-v) (8d) (9a) 625 (3b) (6a-v) (8d) (9a) 626 (3c) (6a-v) (8d) (9a) 627 (4a) (6a-v) (8d) (9a) 628 (4b) (6a-v) (8d) (9a) 629 (4c) (6a-v) (8d) (9a) 630 (4d) (6a-v) (8d) (9a) 631 (4e) (6a-v) (8d) (9a) 632 (4f) (6a-v) (8d) (9a) 633 (4g) (6a-v) (8d) (9a) 634 (4h) (6a-v) (8d) (9a) 635 (5a) (6a-v) (8d) (9a) 636 (5b) (6a-v) (8d) (9a) 637 (5c) (6a-v) (8d) (9a) 638 (5d) (6a-v) (8d) (9a) 639 (5e) (6a-v) (8d) (9a) 640 (5f) (6a-v) (8d) (9a) 641 (1a) (7a) (8a) (9a) 642 (1b) (7a) (8a) (9a) 643 (1c) (7a) (8a) (9a) 644 (1d) (7a) (8a) (9a) 645 (1e) (7a) (8a) (9a) 646 (1f) (7a) (8a) (9a) 647 (1g) (7a) (8a) (9a) 648 (1h) (7a) (8a) (9a) 649 (1i) (7a) (8a) (9a) 650 (2a) (7a) (8a) (9a)GDE Embodiment GDL Catalyst Ionomer Binder 651 (2b) (7a) (8a) (9a) 652 (2c) (7a) (8a) (9a) 653 (2d) (7a) (8a) (9a) 654 (2e) (7a) (8a) (9a) 655 (2f) (7a) (8a) (9a) 656 (3a) (7a) (8a) (9a) 657 (3b) (7a) (8a) (9a) 658 (3c) (7a) (8a) (9a) 659 (4a) (7a) (8a) (9a) 660 (4b) (7a) (8a) (9a) 661 (4c) (7a) (8a) (9a) 662 (4d) (7a) (8a) (9a) 663 (4e) (7a) (8a) (9a) 664 (4f) (7a) (8a) (9a) 665 (4g) (7a) (8a) (9a) 666 (4h) (7a) (8a) (9a) 667 (5a) (7a) (8a) (9a) 668 (5b) (7a) (8a) (9a) 669 (5c) (7a) (8a) (9a) 670 (5d) (7a) (8a) (9a) 671 (5e) (7a) (8a) (9a) 672 (5f) (7a) (8a) (9a) 673 (1a) (7a) (8b) (9a) 674 (1b) (7a) (8b) (9a) 675 (1c) (7a) (8b) (9a) 676 (1d) (7a) (8b) (9a) 677 (1e) (7a) (8b) (9a) 678 (1f) (7a) (8b) (9a) 679 (1g) (7a) (8b) (9a) 680 (1h) (7a) (8b) (9a) 681 (1i) (7a) (8b) (9a) 682 (2a) (7a) (8b) (9a) 683 (2b) (7a) (8b) (9a) 684 (2c) (7a) (8b) (9a) 685 (2d) (7a) (8b) (9a) 686 (2e) (7a) (8b) (9a) 687 (2f) (7a) (8b) (9a) 688 (3a) (7a) (8b) (9a) 689 (3b) (7a) (8b) (9a) 690 (3c) (7a) (8b) (9a)GDE Embodiment GDL Catalyst Ionomer Binder 691 (4a) (7a) (8b) (9a) 692 (4b) (7a) (8b) (9a) 693 (4c) (7a) (8b) (9a) 694 (4d) (7a) (8b) (9a) 695 (4e) (7a) (8b) (9a) 696 (4f) (7a) (8b) (9a) 697 (4g) (7a) (8b) (9a) 698 (4h) (7a) (8b) (9a) 699 (5a) (7a) (8b) (9a) 700 (5b) (7a) (8b) (9a) 701 (5c) (7a) (8b) (9a) 702 (5d) (7a) (8b) (9a) 703 (5e) (7a) (8b) (9a) 704 (5f) (7a) (8b) (9a) 705 (1a) (7a) (8c) (9a) 706 (1b) (7a) (8c) (9a) 707 (1c) (7a) (8c) (9a) 708 (1d) (7a) (8c) (9a) 709 (1e) (7a) (8c) (9a) 710 (1f) (7a) (8c) (9a) 711 (1g) (7a) (8c) (9a) 712 (1h) (7a) (8c) (9a) 713 (1i) (7a) (8c) (9a) 714 (2a) (7a) (8c) (9a) 715 (2b) (7a) (8c) (9a) 716 (2c) (7a) (8c) (9a) 717 (2d) (7a) (8c) (9a) 718 (2e) (7a) (8c) (9a) 719 (2f) (7a) (8c) (9a) 720 (3a) (7a) (8c) (9a) 721 (3b) (7a) (8c) (9a) 722 (3c) (7a) (8c) (9a) 723 (4a) (7a) (8c) (9a) 724 (4b) (7a) (8c) (9a) 725 (4c) (7a) (8c) (9a) 726 (4d) (7a) (8c) (9a) 727 (4e) (7a) (8c) (9a) 728 (4f) (7a) (8c) (9a) 729 (4g) (7a) (8c) (9a) 730 (4h) (7a) (8c) (9a)GDE Embodiment GDL Catalyst Ionomer Binder 731 (5a) (7a) (8c) (9a) 732 (5b) (7a) (8c) (9a) 733 (5c) (7a) (8c) (9a) 734 (5d) (7a) (8c) (9a) 735 (5e) (7a) (8c) (9a) 736 (5f) (7a) (8c) (9a) 737 (1a) (7a) (8d) (9a) 738 (1b) (7a) (8d) (9a) 739 (1c) (7a) (8d) (9a) 740 (1d) (7a) (8d) (9a) 741 (1e) (7a) (8d) (9a) 742 (1f) (7a) (8d) (9a) 743 (1g) (7a) (8d) (9a) 744 (1h) (7a) (8d) (9a) 745 (1i) (7a) (8d) (9a) 746 (2a) (7a) (8d) (9a) 747 (2b) (7a) (8d) (9a) 748 (2c) (7a) (8d) (9a) 749 (2d) (7a) (8d) (9a) 750 (2e) (7a) (8d) (9a) 751 (2f) (7a) (8d) (9a) 752 (3a) (7a) (8d) (9a) 753 (3b) (7a) (8d) (9a) 754 (3c) (7a) (8d) (9a) 755 (4a) (7a) (8d) (9a) 756 (4b) (7a) (8d) (9a) 757 (4c) (7a) (8d) (9a) 758 (4d) (7a) (8d) (9a) 759 (4e) (7a) (8d) (9a) 760 (4f) (7a) (8d) (9a) 761 (4g) (7a) (8d) (9a) 762 (4h) (7a) (8d) (9a) 763 (5a) (7a) (8d) (9a) 764 (5b) (7a) (8d) (9a) 765 (5c) (7a) (8d) (9a) 766 (5d) (7a) (8d) (9a) 767 (5e) (7a) (8d) (9a) 768 (5f) (7a) (8d) (9a) 769 (1a) (6a-x) (8a) (9a) 770 (1b) (6a-x) (8a) (9a)GDE Embodiment GDL Catalyst Ionomer Binder 771 (1c) (6a-x) (8a) (9a) 772 (1d) (6a-x) (8a) (9a) 773 (1e) (6a-x) (8a) (9a) 774 (1f) (6a-x) (8a) (9a) 775 (1g) (6a-x) (8a) (9a) 776 (1h) (6a-x) (8a) (9a) 777 (1i) (6a-x) (8a) (9a) 778 (2a) (6a-x) (8a) (9a) 779 (2b) (6a-x) (8a) (9a) 780 (2c) (6a-x) (8a) (9a) 781 (2d) (6a-x) (8a) (9a) 782 (2e) (6a-x) (8a) (9a) 783 (2f) (6a-x) (8a) (9a) 784 (3a) (6a-x) (8a) (9a) 785 (3b) (6a-x) (8a) (9a) 786 (3c) (6a-x) (8a) (9a) 787 (4a) (6a-x) (8a) (9a) 788 (4b) (6a-x) (8a) (9a) 789 (4c) (6a-x) (8a) (9a) 790 (4d) (6a-x) (8a) (9a) 791 (4e) (6a-x) (8a) (9a) 792 (4f) (6a-x) (8a) (9a) 793 (4g) (6a-x) (8a) (9a) 794 (4h) (6a-x) (8a) (9a) 795 (5a) (6a-x) (8a) (9a) 796 (5b) (6a-x) (8a) (9a) 797 (5c) (6a-x) (8a) (9a) 798 (5d) (6a-x) (8a) (9a) 799 (5e) (6a-x) (8a) (9a) 800 (5f) (6a-x) (8a) (9a) 801 (1a) (6a-x) (8b) (9a) 802 (1b) (6a-x) (8b) (9a) 803 (1c) (6a-x) (8b) (9a) 804 (1d) (6a-x) (8b) (9a) 805 (1e) (6a-x) (8b) (9a) 806 (1f) (6a-x) (8b) (9a) 807 (1g) (6a-x) (8b) (9a) 808 (1h) (6a-x) (8b) (9a) 809 (1i) (6a-x) (8b) (9a) 810 (2a) (6a-x) (8b) (9a)GDE Embodiment GDL Catalyst Ionomer Binder 811 (2b) (6a-x) (8b) (9a) 812 (2c) (6a-x) (8b) (9a) 813 (2d) (6a-x) (8b) (9a) 814 (2e) (6a-x) (8b) (9a) 815 (2f) (6a-x) (8b) (9a) 816 (3a) (6a-x) (8b) (9a) 817 (3b) (6a-x) (8b) (9a) 818 (3c) (6a-x) (8b) (9a) 819 (4a) (6a-x) (8b) (9a) 820 (4b) (6a-x) (8b) (9a) 821 (4c) (6a-x) (8b) (9a) 822 (4d) (6a-x) (8b) (9a) 823 (4e) (6a-x) (8b) (9a) 824 (4f) (6a-x) (8b) (9a) 825 (4g) (6a-x) (8b) (9a) 826 (4h) (6a-x) (8b) (9a) 827 (5a) (6a-x) (8b) (9a) 828 (5b) (6a-x) (8b) (9a) 829 (5c) (6a-x) (8b) (9a) 830 (5d) (6a-x) (8b) (9a) 831 (5e) (6a-x) (8b) (9a) 832 (5f) (6a-x) (8b) (9a) 833 (1a) (6a-x) (8c) (9a) 834 (1b) (6a-x) (8c) (9a) 835 (1c) (6a-x) (8c) (9a) 836 (1d) (6a-x) (8c) (9a) 837 (1e) (6a-x) (8c) (9a) 838 (1f) (6a-x) (8c) (9a) 839 (1g) (6a-x) (8c) (9a) 840 (1h) (6a-x) (8c) (9a) 841 (1i) (6a-x) (8c) (9a) 842 (2a) (6a-x) (8c) (9a) 843 (2b) (6a-x) (8c) (9a) 844 (2c) (6a-x) (8c) (9a) 845 (2d) (6a-x) (8c) (9a) 846 (2e) (6a-x) (8c) (9a) 847 (2f) (6a-x) (8c) (9a) 848 (3a) (6a-x) (8c) (9a) 849 (3b) (6a-x) (8c) (9a) 850 (3c) (6a-x) (8c) (9a)GDE Embodiment GDL Catalyst Ionomer Binder 851 (4a) (6a-x) (8c) (9a) 852 (4b) (6a-x) (8c) (9a) 853 (4c) (6a-x) (8c) (9a) 854 (4d) (6a-x) (8c) (9a) 855 (4e) (6a-x) (8c) (9a) 856 (4f) (6a-x) (8c) (9a) 857 (4g) (6a-v) (8c) (9a) 858 (4h) (6a-x) (8c) (9a) 859 (5a) (6a-x) (8c) (9a) 860 (5b) (6a-x) (8c) (9a) 861 (5c) (6a-x) (8c) (9a) 862 (5d) (6a-x) (8c) (9a) 863 (5e) (6a-x) (8c) (9a) 864 (5f) (6a-x) (8c) (9a) 865 (1a) (6a-x) (8d) (9a) 866 (1b) (6a-x) (8d) (9a) 867 (1c) (6a-x) (8d) (9a) 868 (1d) (6a-x) (8d) (9a) 869 (1e) (6a-x) (8d) (9a) 870 (1f) (6a-x) (8d) (9a) 871 (1g) (6a-x) (8d) (9a) 872 (1h) (6a-x) (8d) (9a) 873 (1i) (6a-x) (8d) (9a) 874 (2a) (6a-x) (8d) (9a) 875 (2b) (6a-x) (8d) (9a) 876 (2c) (6a-x) (8d) (9a) 877 (2d) (6a-x) (8d) (9a) 878 (2e) (6a-x) (8d) (9a) 879 (2f) (6a-x) (8d) (9a) 880 (3a) (6a-x) (8d) (9a) 881 (3b) (6a-x) (8d) (9a) 882 (3c) (6a-x) (8d) (9a) 883 (4a) (6a-x) (8d) (9a) 884 (4b) (6a-x) (8d) (9a) 885 (4c) (6a-x) (8d) (9a) 886 (4d) (6a-x) (8d) (9a) 887 (4e) (6a-x) (8d) (9a) 888 (4f) (6a-x) (8d) (9a) 889 (4g) (6a-x) (8d) (9a) 890 (4h) (6a-x) (8d) (9a)GDE Embodiment GDL Catalyst Ionomer Binder 891 (5a) (6a-x) (8d) (9a) 892 (5b) (6a-x) (8d) (9a) 893 (5c) (6a-x) (8d) (9a) 894 (5d) (6a-x) (8d) (9a) 895 (5e) (6a-x) (8d) (9a) 896 (5f) (6a-x) (8d) (9a)

[0147] Additional particular embodiments of GDEs of the present disclosure include GDE embodiments 1a-896a each having components as defined in GDE Embodiments 1-896 but excluding a binder.

[0148] Various additional embodiments of GDEs of the present disclosure will be appreciated by the skilled person. For example, in respect of GDE-1 type GDEs as described herein, any of Embodiments 1-896 or 1a-896a for these GDEs may further comprise an AEM as described herein, for example as shown in FIGs. 1(e)-(h). Further, in respect of GDE-1, GDE-2 and GDE-4 type GDEs as described herein, any of Embodiments 1-896 or 1a-896a for these GDEs may further comprise an MPL as described herein, for example as shown in FIGs. 1(b), (d), (f) and (h), FIGs. 2(b) and (d), and FIGs. 4(b) and 4(d). Further, in respect of GDE-1, GDE-2, GDE-3, and GDE-4 type GDEs as described herein, any of Embodiments 1-896 or 1a-896a for these GDEs may further comprise a mesh as described herein, for example as shown in FIGs. 1(c)-(h), 2(c)-(d), 3(b) and 4(c) and 4(d).

[0149] As described herein, the GDE-4 comprises a 1stGDL and a 2ndGDL, each of which may be the same or different. With respect to GDE-4, in any of Embodiments 1-896 or 1a-896a at least one of the 1stGDL and the 2ndGDL is the GDL as defined for the respective embodiment of Embodiments 1-896 or 1a-896a. In an embodiment, the 1stGDL and the 2ndGDL are the same, and both of the GDLs in GDE-4 are as defined for the respective embodiment of Embodiments 1-896 or 1a-896a. In another embodiment, the 1stGDL and the 2ndGDL are different and only one of the GDLs is as defined for the respective embodiment of Embodiments 1-896 or 1a-896a. In an embodiment where the GDLs in the GDE-4 are different, it is the 1stGDL that is as defined for the respective embodiment of Embodiments 1-896 or 1a-896a. In an embodiment where the GDLs in the GDE-4 are different, it is the 2ndGDL that is as defined for the respective embodiment of Embodiments 1-896 or 1a-896a.Anion Exchange Membrane (AEM)

[0150] In an embodiment, the GDE-1, GDE-2 or GDE-4 of the present disclosure may comprise an AEM. Embodiments of AEMs are described elsewhere herein and that disclosure is equally applicable to AEMs that are a component of the GDE.

[0151] In an embodiment, the AEM of the GDE comprises a polymer having at least one positively charged cationic group bound to at least a portion of a polymeric backbone. In an embodiment, the polymer comprises polyalkylene, a polyfluorene, a poly(arylene ether), a polysulfone, a poly(arylene ether sulfone), a polyetherketone, a polyetherimide, a poly(ether oxadiazole), a poly(phenylene oxide), a poly(vinyl benzyl), a polyphenylene, a perfluoro, a polybenzimidazole, a polystyrene, or a polyphosphazene. In an embodiment, the positively charged cationic group is a primary, secondary, tertiary or quaternary ammonium, a heterocyclic cation, a guanidinium, a phosphonium, a sulfonium, or a metal cation.

[0152] In an embodiment, the AEM of the GDE is a FumasepTM, a NeoseptaTM, an OrionTM, a Xergy Xion PentionTM, a PiperIONTM, a RalexTM, a SustanionTM, or an IonomrTManion exchange membrane. Membrane electrolysis cell

[0153] In an embodiment, the present disclosure relates to a membrane electrolysis cell comprising any one of the GDEs as described herein. One or more ion exchange membranes are stacked in an order specific to the components of the brine stream being processed as well as the desired outputs. The membranes are designed to allow specific charged ionic species permeate through. Cation exchange membranes transfer cationic species while anion exchange membrane only allow anions transport through the membrane structure. The movement of ions is enabled by applying an external voltage using a cathode and anode electrode. Under applied voltage, anions travel toward the positively charged anode while cations travel towards the negatively charged cathode. Through careful placement of membranes, desired chemicals such acids, bases, and salts can be produced.

[0154] In another embodiment of the present disclosure, the process disclosed herein for producing a base product (e.g. an alkali metal compound) involves the use of a membrane electrolysis cell together with the GDE described herein.

[0155] Various different types of multi-compartment membrane electrolysis cells may be used, such as those described herein. 5-compartment membrane electrolysis cell

[0156] In an embodiment, the membrane electrolysis cell comprises five compartments as depicted in FIG. 5. The membrane electrolysis cell comprises a base build up compartment, a salt depletion compartment and an acid build-up compartment interposed between a cathode compartment and an anode compartment. The base build-up compartment is interposed between the cathode compartment and the salt depletion compartment, the salt depletion compartment is interposed between the base build-up compartment and the acid build-up compartment, and the acid build-up compartment is interposed between the salt depletion compartment and the anode compartment.

[0157] An anode is housed in the anode compartment.

[0158] A cathode comprising a gas diffusion electrode (GDE) is housed in the cathode compartment, wherein: ^ When the GDE is GDE-1 described herein, the CL of the GDEs shown in FIGs. 1(a)-(d) is in direct contact with the 1stAEM shown in FIG. 5. Otherwise, the AEM of the GDEs shown in FIGs. 1(e)-(h) is the 1stAEM shown in FIG. 5. The 1stAEM defines a boundary between the cathode compartment and the base build-up compartment. The cathode compartment is in fluid communication with the base build-up compartment via the 1stAEM. The base build-up compartment is defined by the 1stAEM and a 1stCEM. ^ When the GDE is GDE-2 described herein, the CCM of the GDEs shown in FIGs. 2(a)-(d) is in place of the 1stAEM shown in FIG. 5. The CCM defines a boundary between the cathode compartment and the base build-up compartment. The cathode compartment is in fluid communication with the base build-up compartment via the CCM. The base build-up compartment is defined by the CCM and the 1stCEM.^ When the GDE is GDE-3 described herein, the 1stAEM shown in FIG.5 is omitted resulting in the cathode compartment and the base build-up compartment becoming a single compartment. Therefore, use of GDE-3 without the 1stAEM effectively renders the cell to a 4-compartment membrane electrolysis cell. ^ When the GDE is GDE-4 described herein, the AEM of the GDEs shown in FIGs. 4(a)-(d) is the 1stAEM shown in FIG. 5. The 1stAEM defines a boundary between the cathode compartment and the base build-up compartment. The cathode compartment is in fluid communication with the base build-up compartment via the 1stAEM. The base build-up compartment is defined by the 1stAEM and a 1stCEM.

[0159] The 1stCEM defines a boundary between the base build-up compartment and the salt depletion compartment. The base build-up compartment is in fluid communication with the salt depletion compartment via the 1stCEM. The salt depletion compartment is defined by the 1stCEM and a 2ndAEM. The 2ndAEM defines a boundary between the salt depletion compartment and the acid build-up compartment. The salt depletion compartment is in fluid communication with the acid build-up compartment via the 2ndAEM. The acid build-up compartment is defined by the 2ndAEM and a 2ndCEM. The 2ndCEM defines a boundary between the acid build-up compartment and the anode compartment. The acid build-up compartment is in fluid communication with the anode compartment via the 2ndCEM.

[0160] The 1stand 2ndAEMs are as described herein and may be the same or different. The 1stand 2ndCEMs are as described herein and may be the same or different.

[0161] In operation, a salt solution comprising positive ions and negative ions is fed to the salt depletion compartment. A gas comprising oxygen is fed to the GDE in the cathode compartment. When a voltage is applied across the anode and cathode, the positive ions from the salt solution migrate towards the negatively charged cathode compartment through the 1stCEM and remain in the base build-up compartment, since they cannot pass through the 1stAEM (GDE-1 and GDE-4), the CCM (GDE-2), or the catalyst layer (GDE-3). Likewise, the OH- anions produced at the GDE build up in the base build-up compartment since they will migrate away from the negatively charged cathode towards the positively charged anode through the 1stAEM (GDE-1 and GDE-4), the CCM (GDE-2), or the catalyst layer (GDE-3).Like the positive ions, the OH- ions remain in the base build-up compartment because they cannot pass through the 1stCEM. Therefore, a base is formed in the base build-up compartment. As shown in FIG. 5, the negative ions from the salt solution migrate towards the positively charged anode compartment through the 2ndAEM and remain in the acid build-up compartment, since they cannot pass through the 2ndCEM. The anodic reaction results in the formation of protons which are then transported through the 2ndCEM into the acid build-up compartment. The protons combine with the negative ions to form an acid.

[0162] If the salt solution comprises LiCl, Li2SO4, Li3PO4, LiNO3, or LiI, then LiOH will be produced in the base build-up compartment and HCl, H2SO4, H3PO4, HNO3, HI, respectively, will be produced simultaneously in the acid build-up compartment. Likewise, if the salt solution comprises NaCl, Na2SO4, Na3PO4, NaNO3, or NaI, then NaOH will be produced in the base build-up compartment and HCl, H2SO4, H3PO4, HNO3, HI, respectively, will be produced simultaneously in the acid build-up compartment. And, if the salt solution comprises KCl, K2SO4, K3PO4, KNO3, or KI, then KOH will be produced in the base build-up compartment and HCl, H2SO4, H3PO4, HNO3, HI, respectively, will be produced simultaneously in the acid build-up compartment.

[0163] Thus, in an embodiment, the present disclosure relates to a membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up compartment, a salt depletion compartment and an acid build-up compartment interposed between the cathode compartment and the anode compartment, the base build-up compartment is interposed between the cathode compartment and the salt depletion compartment, the salt depletion compartment is interposed between the base build-up compartment and the acid build-up compartment, and the acid build-up compartment is interposed between the salt depletion compartment and the anode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a GDE-1 as described herein positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a first anion exchange membrane, the first anion exchange membrane being disposed on the catalyst layer of the gas diffusion electrode and being configured to exchange ions received from the catalyst layer of the gas diffusion electrode to an opposed surface of the first anion ion exchange membrane into the base build-up compartment; a first cation exchange membrane interposed between the salt depletion compartment and the base build-up compartment, thecation exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the cation exchange membrane into the base build-up compartment; a second anion exchange membrane interposed between the salt depletion compartment and the acid build-up compartment, the second anion exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the second anion exchange membrane into the acid build-up compartment; a second cation exchange membrane interposed between the acid build-up compartment and the anode compartment, the second cation exchange membrane being configured to exchange ions received from the anode compartment to an opposed surface of the second cation exchange membrane into the acid build-up compartment; an inlet through which the salt-containing solution is received into the salt depletion compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2 is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

[0164] In another embodiment, the present disclosure relates to a process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in the immediately preceding paragraph, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the salt depletion compartment; the positive salt ions migrate through the first cation exchange membrane to the opposed surface of the cation exchange membrane into the base build-up compartment; the gas comprising O2 is reduced at the cathode to form OH-; the OH- ions migrate through the first anion exchange membrane to the opposed surface of the first anion exchange membrane into the base build-up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the base build-up compartment.

[0165] In another embodiment, the present disclosure relates to a membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up compartment, a salt depletion compartment and an acid build-up compartment interposed between the cathode compartment and the anode compartment, the base build-up compartment is interposed between the cathode compartment and the salt depletion compartment, the saltdepletion compartment is interposed between the base build-up compartment and the acid build-up compartment, and the acid build-up compartment is interposed between the salt depletion compartment and the anode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a GDE-2 as described herein positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a first cation exchange membrane interposed between the salt depletion compartment and the base build-up compartment, the cation exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the cation exchange membrane into the base build-up compartment; an anion exchange membrane interposed between the salt depletion compartment and the acid build-up compartment, the anion exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the anion exchange membrane into the acid build-up compartment; a second cation exchange membrane interposed between the acid build-up compartment and the anode compartment, the second cation exchange membrane being configured to exchange ions received from the anode compartment to an opposed surface of the second cation exchange membrane into the acid build-up compartment; an inlet through which the salt-containing solution is received into the salt depletion compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2 is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

[0166] In another embodiment, the present disclosure relates to a process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in the immediately preceding paragraph, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the salt depletion compartment; the positive salt ions migrate through the first cation exchange membrane to the opposed surface of the first cation exchange membrane into the base build-up compartment; the gas comprising O2 is reduced at the cathode to form OH-; the OH- ions migrate through the catalyst coated membrane into the base build-up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the base build-up compartment.

[0167] In another embodiment, the present disclosure relates to a membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up together with the cathode compartment forming a single compartment; a salt depletion compartment and an acid build up compartment interposed between the cathode compartment and the anode compartment, the salt depletion compartment is interposed between the base build-up compartment and the acid build-up compartment, and the acid build-up compartment is interposed between the salt depletion compartment and the anode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a GDE-3 as described herein positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a first cation exchange membrane interposed between the salt depletion compartment and the base build-up compartment, the cation exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the cation exchange membrane into the base build-up compartment; an anion exchange membrane interposed between the salt depletion compartment and the acid build-up compartment, the anion exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the anion exchange membrane into the acid build-up compartment; a second cation exchange membrane interposed between the acid build-up compartment and the anode compartment, the second cation exchange membrane being configured to exchange ions received from the anode compartment to an opposed surface of the second cation exchange membrane into the acid build-up compartment; an inlet through which the salt-containing solution is received into the salt depletion compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

[0168] In another embodiment, the present disclosure relates to a process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in the immediately preceding paragraph, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the salt depletion compartment; the positive salt ionsmigrate through the first cation exchange membrane to the opposed surface of the first cation exchange membrane into the base build-up compartment; the gas comprising O2 is reduced at the cathode to form OH-; the OH- ions migrate through the catalyst layer into the base build-up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the membrane electrolysis cell. 4-compartment membrane electrolysis cell

[0169] In an embodiment, the membrane electrolysis cell comprises four compartments as depicted in FIG. 6. The membrane electrolysis cell comprises a base build-up compartment and a salt depletion compartment interposed between a cathode compartment and an anode compartment. The base build-up compartment is interposed between the cathode compartment and the salt depletion compartment, and the salt depletion compartment is interposed between the base build-up compartment and the anode compartment.

[0170] An anode is housed in the anode compartment.

[0171] A cathode comprising a gas diffusion electrode (GDE) is housed in the cathode compartment, wherein: ^ When the GDE is GDE-1 described herein, the CL of the GDEs shown in FIGs. 1(a)-(d) is in direct contact with a 1stAEM shown in FIG. 6. Otherwise, the AEM of the GDEs shown in FIGs. 1(e)-(h) is the 1stAEM shown in FIG. 6. The 1stAEM defines a boundary between the cathode compartment and the base build-up compartment. The cathode compartment is in fluid communication with the base build-up compartment via the 1stAEM. The base build-up compartment is defined by the 1stAEM and a CEM. ^ When the GDE is GDE-2 described herein, the CCM of the GDEs shown in FIGs. 2(a)-(d) is in place of the 1stAEM shown in FIG. 6. The CCM defines a boundary between the cathode compartment and the base build-up compartment. The cathode compartment is in fluidcommunication with the base build-up compartment via the CCM. The base build-up compartment is defined by the CCM and the CEM. ^ When the GDE is GDE-3 described herein, the 1stAEM shown in FIG.6 is omitted resulting in the cathode compartment and the base build-up compartment becoming a single compartment. Therefore, use of GDE-3 without the 1stAEM effectively renders the cell to a 3-compartment membrane electrolysis cell. ^ When the GDE is GDE-4 described herein, the AEM of the GDEs shown in FIGs. 4(a)-(d) is the 1stAEM shown in FIG. 6. The 1stAEM defines a boundary between the cathode compartment and the base build-up compartment. The cathode compartment is in fluid communication with the base build-up compartment via the 1stAEM. The base build-up compartment is defined by the 1stAEM and a CEM.

[0172] The CEM defines a boundary between the base build-up compartment and the salt depletion compartment. The base build-up compartment is in fluid communication with the salt depletion compartment via the CEM. The salt depletion compartment is defined by the CEM and a 2ndAEM. The 2ndAEM defines a boundary between the salt depletion compartment and the anode compartment. The salt depletion compartment is in fluid communication with the anode compartment via the 2ndAEM.

[0173] The 1stand 2ndAEMs are as described herein and may be the same or different. The CEM is as described herein.

[0174] In operation, a salt solution comprising positive ions and negative ions is fed to the salt depletion compartment. A gas comprising oxygen is fed to the GDE in the cathode compartment. When a voltage is applied across the anode and cathode, the positive ions form the salt solution migrate towards the negatively charged cathode compartment through the CEM and remain in the base build-up compartment, since they cannot pass through the 1stAEM (GDE-1 and GDE-4), the CCM (GDE-2), or the catalyst layer (GDE-3). Likewise, the OH- anions produced at the GDE build up in the base build-up compartment since they will migrate away from the negatively charged cathode towards the positively charged anode through the 1stAEM (GDE-1 and GDE-4), the CCM (GDE-2), or the catalyst layer (GDE-3). Like the positive ions, the OH- ions remain in the base build-up compartment because theycannot pass through the CEM. Therefore, a base is formed in the base build-up compartment. As shown in FIG. 6, the negative ions from the salt solution migrate towards the positively charged anode compartment through the 2ndAEM into the anode compartment.

[0175] If the salt solution comprises (a) LiCl, LiBr, or LiI, (b) NaCl, NaBr, or NaI, or (c) KCl, KBr, or KI, then (a) LiOH, (b) NaOH, or (c) KOH, respectively, will be produced in the base build-up compartment. Simultaneously, HCl, HBr or HI will be produced in the anode compartment (dependent of the input salt solution) with the possibility of production of Cl2, Br2or I2, respectively.

[0176] If the salt solution comprises Li2SO4, Li3PO4, or LiNO3, then LiOH will be produced in the base build-up compartment and H2SO4, H3PO4, or HNO3, respectively, will be produced simultaneously in the anode compartment. Likewise, if the salt solution comprises Na2SO4, Na3PO4, or NaNO3, then NaOH will be produced in the base build-up compartment and H2SO4, H3PO4, or HNO3, respectively, will be produced simultaneously in the anode compartment. And, if the salt solution comprises K2SO4, K3PO4, or KNO3, then KOH will be produced in the base build-up compartment and H2SO4, H3PO4, or HNO3, respectively, will be produced simultaneously in the anode compartment.

[0177] Thus, in an embodiment, the present disclosure relates to a membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up compartment and a salt depletion compartment interposed between the cathode compartment and the anode compartment, the base build-up compartment is interposed between the cathode compartment and the salt depletion compartment, and the salt depletion compartment is interposed between the base build-up compartment and the anode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a GDE-1 as described herein positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a first anion exchange membrane being disposed on the catalyst layer of the gas diffusion electrode and being configured to exchange ions received from the catalyst layer of the gas diffusion electrode to an opposed surface of the first anion ion exchange membrane into the base build-up compartment; a cation exchange membrane interposed between the salt depletion compartment and the base build-up compartment, the cation exchange membrane being configured to exchange ions received from the salt depletion compartment to anopposed surface of the cation exchange membrane into the base build-up compartment; a second anion exchange membrane interposed between the salt depletion compartment and the anode compartment, the second anion exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the second anion exchange membrane into the anode compartment; an inlet through which the salt-containing solution is received into the salt depletion compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

[0178] In another embodiment, the present disclosure relates to a process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in the immediately preceding paragraph, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the salt depletion compartment; the positive salt ions migrate through the cation exchange membrane to the opposed surface of the cation exchange membrane into the base build-up compartment; the gas comprising O2is reduced at the cathode to form OH-; the OH- ions migrate through the first anion exchange membrane to the opposed surface of the first anion exchange membrane into the base build-up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the base build-up compartment.

[0179] In another embodiment, the present disclosure relates to a membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up compartment and a salt depletion compartment interposed between the cathode compartment and the anode compartment, the base build-up compartment is interposed between the cathode compartment and the salt depletion compartment, and the salt depletion compartment is interposed between the base build-up compartment and the anode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a GDE-2 as described herein positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a cation exchange membrane interposed between the salt depletion compartment and thebase build-up compartment, the cation exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the cation exchange membrane into the base build-up compartment; an anion exchange membrane interposed between the salt depletion compartment and the anode compartment, the anion exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the anion exchange membrane into the anode compartment; an inlet through which the salt-containing solution is received into the salt depletion compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

[0180] In another embodiment, the present disclosure relates to a process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in the immediately preceding paragraph, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the salt depletion compartment; the positive salt ions migrate through the cation exchange membrane to the opposed surface of the cation exchange membrane into the base build-up compartment; the gas comprising O2 is reduced at the cathode to form OH-; the OH- ions migrate through the catalyst coated exchange membrane into the base build-up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the base build-up compartment.

[0181] In another embodiment, the present disclosure relates to a membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up together with the cathode compartment forming a single compartment; a salt depletion compartment interposed between the cathode compartment and the anode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a GDE-3 as described herein positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a cation exchange membrane interposed between the salt depletion compartment and the base build-up compartment, the cation exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the cationexchange membrane into the base build-up compartment; an anion exchange membrane interposed between the salt depletion compartment and the anode compartment, the anion exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the anion exchange membrane into the anode compartment; an inlet through which the salt-containing solution is received into the salt depletion compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

[0182] In another embodiment, the present disclosure relates to a process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in the immediately preceding paragraph, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the salt depletion compartment; the positive salt ions migrate through the cation exchange membrane to the opposed surface of the cation exchange membrane into the base build-up compartment; the gas comprising O2 is reduced at the cathode to form OH-; the OH- ions migrate through the catalyst layer into the base build-up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the membrane electrolysis cell. 3-compartment membrane electrolysis cell

[0183] In an embodiment, the membrane electrolysis cell comprises three compartments as depicted in FIG. 7. The membrane electrolysis cell comprises a base build-up compartment interposed between a cathode compartment and an anode compartment.

[0184] An anode is housed in the anode compartment.

[0185] A cathode comprising a gas diffusion electrode (GDE) is housed in the cathode compartment, wherein: ^ When the GDE is GDE-1 described herein, the CL of the GDEs shown in FIGs.1(a)-(d) is in direct contact with an AEM shown in FIG.7. Otherwise,the AEM of the GDEs shown in FIGs.1(e)-(h) is the AEM shown in FIG. 7. The AEM defines a boundary between the cathode compartment and the base build-up compartment. The cathode compartment is in fluid communication with the base build-up compartment via the AEM. The base build-up compartment is defined by the AEM and a CEM. ^ When the GDE is GDE-2 described herein, the CCM of the GDEs shown in FIGs.2(a)-(d) is in place of the AEM shown in FIG.7. The CCM defines a boundary between the cathode compartment and the base build-up compartment. The cathode compartment is in fluid communication with the base build-up compartment via the CCM. The base build-up compartment is defined by the CCM and the CEM. ^ When the GDE is GDE-3 described herein, the AEM shown in FIG. 7 is omitted resulting in the cathode compartment and the base build-up compartment becoming a single compartment. Therefore, use of GDE-3 without the AEM effectively renders the cell to a 2-compartment membrane electrolysis cell. ^ When the GDE is GDE-4 described herein, the AEM of the GDEs shown in FIGs.4(a)-(d) is the AEM shown in FIG. 7. The AEM defines a boundary between the cathode compartment and the base build-up compartment. The cathode compartment is in fluid communication with the base build-up compartment via the AEM. The base build-up compartment is defined by the AEM and a CEM.

[0186] The CEM defines a boundary between the base build-up compartment and the anode compartment. The base build-up compartment is in fluid communication with the anode compartment via the CEM.

[0187] The CEM and AEM are as described herein.

[0188] In operation, a salt solution comprising positive ions and negative ions is fed to the anode compartment. A gas comprising oxygen is fed to the GDE in the cathode compartment. When a voltage is applied across the anode and cathode, the positive ions from the salt solution migrate towards the negatively charged cathode compartment throughthe CEM and remain in the base build-up compartment, since they cannot pass through the AEM (GDE-1 and GDE-4), the CCM (GDE-2), or the catalyst layer (GDE-3). Likewise, the OH- anions produced at the GDE build up in the base build-up compartment since they will migrate away from the negatively charged cathode towards the positively charged anode through the AEM (GDE-1 and GDE-4), the CCM (GDE-2), or the catalyst layer (GDE-3). Like the positive ions, the OH- ions remain in the base build-up compartment because they cannot pass through the CEM. Therefore, a base is formed in the base build-up compartment.

[0189] If the salt solution comprises (a) LiCl, LiBr, or LiI, (b) NaCl, NaBr, or NaI, or (c) KCl, KBr, or KI, then (a) LiOH, (b) NaOH, or (c) KOH, respectively, will be produced in the base build-up compartment. Simultaneously, HCl, HBr or HI will be produced in the anode compartment (dependent of the input salt solution) with the possibility of production of Cl2, Br2or I2, respectively.

[0190] If the salt solution comprises Li2SO4, Li3PO4, or LiNO3, then LiOH will be produced in the base build-up compartment and H2SO4, H3PO4, or HNO3, respectively, will be produced simultaneously in the anode compartment. Likewise, if the salt solution comprises Na2SO4, Na3PO4, or NaNO3, then NaOH will be produced in the base build-up compartment and H2SO4, H3PO4, or HNO3, respectively, will be produced simultaneously in the anode compartment. And, if the salt solution comprises K2SO4, K3PO4, or KNO3, then KOH will be produced in the base build-up compartment and H2SO4, H3PO4, or HNO3, respectively, will be produced simultaneously in the anode compartment.

[0191] Thus, in an embodiment, the present disclosure relates to a membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up compartment interposed between the cathode compartment and the anode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a GDE-1 as described herein positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; an anion exchange membrane being disposed on the catalyst layer of the gas diffusion electrode and being configured to exchange ions received from the catalyst layer of the gas diffusion electrode to an opposed surface of the anion ion exchange membrane into the base build-up compartment; a cation exchange membrane interposed between the anode compartment and the base build up compartment, the cation exchange membrane beingconfigured to exchange ions received from the anode to an opposed surface of the cation exchange membrane into the base build-up compartment; an inlet through which the salt-containing solution is received into the anode compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2 is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

[0192] In another embodiment, the present disclosure relates to a process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in the immediately preceding paragraph, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the anode compartment; the positive salt ions migrate through the cation exchange membrane to the opposed surface of the cation exchange membrane into the base build-up compartment; the gas comprising O2is reduced at the cathode to form OH-; the OH- ions migrate through the anion exchange membrane to the opposed surface of the anion exchange membrane into the base build up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the base build-up compartment.

[0193] In another embodiment, the present disclosure relates to a membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up compartment interposed between the cathode compartment and the anode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a GDE-2 as described herein positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a cation exchange membrane interposed between the anode compartment and the base build-up compartment, the cation exchange membrane being configured to exchange ions received from the anode to an opposed surface of the cation exchange membrane into the base build-up compartment; an inlet through which the salt-containing solution is received into the anode compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

[0194] In another embodiment, the present disclosure relates to a process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in the immediately preceding paragraph, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the anode compartment; the positive salt ions migrate through the cation exchange membrane to the opposed surface of the cation exchange membrane into the base build-up compartment; the gas comprising O2 is reduced at the cathode to form OH-; the OH- ions migrate through the catalyst coated membrane into the base build-up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the base build-up compartment.

[0195] In another embodiment, the present disclosure relates to a membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up together with the cathode compartment forming a single compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a GDE-3 as described herein positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a cation exchange membrane interposed between the anode compartment and the base build-up compartment, the cation exchange membrane being configured to exchange ions received from the anode to an opposed surface of the cation exchange membrane into the base build-up compartment; an inlet through which the salt-containing solution is received into the anode compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

[0196] In another embodiment, the present disclosure relates to a process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in the immediately preceding paragraph, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the anode compartment; the positive salt ions migrate through the cation exchange membrane to the opposed surface of the cation exchangemembrane into the base build-up compartment; the gas comprising O2 is reduced at the cathode to form OH-; the OH- ions migrate through the catalyst layer into the base build-up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the membrane electrolysis cell. 2-compartment membrane electrolysis cell

[0197] In an embodiment, the membrane electrolysis cell comprises two compartments as depicted in FIG. 8. The membrane electrolysis cell comprises a cathode compartment and an anode compartment. The cathode and anode compartments are in fluid communication via a CEM. The CEM is as described herein.

[0198] An anode is housed in the anode compartment.

[0199] A cathode comprising a GDE as shown in FIGs. 1(a)-(d) is housed in the cathode compartment. In this embodiment, the cathode compartment also acts as a base build-up compartment in the region between the CEM and the CL of the GDE.

[0200] In operation, a salt solution comprising positive ions and negative ions is fed to the anode compartment. A gas comprising oxygen is fed to the GDE in the cathode compartment. When a voltage is applied across the anode and cathode, the positive ions migrate towards the negatively charged cathode compartment through the CEM. The OH- anions produced at the GDE remain in the cathode compartment because they cannot pass through the CEM. Therefore, a base is formed in the cathode compartment.

[0201] If the salt solution comprises (a) LiCl, LiBr, or LiI, (b) NaCl, NaBr, or NaI, or (c) KCl, KBr, or KI, then (a) LiOH, (b) NaOH, or (c) KOH, respectively, will be produced in the cathode compartment. Simultaneously, HCl, HBr or HI will be produced in the anode compartment (dependent of the input salt solution) with the possibility of production of Cl2, Br2 or I2, respectively.

[0202] If the salt solution comprises Li2SO4, Li3PO4, or LiNO3, then LiOH will be produced in the cathode compartment and H2SO4, H3PO4, or HNO3, respectively, will be produced simultaneously in the anode compartment. Likewise, if the salt solution comprises Na2SO4, Na3PO4, or NaNO3, then NaOH will be produced in the cathode compartment and H2SO4, H3PO4, or HNO3, respectively, will be produced simultaneously in the anodecompartment. And, if the salt solution comprises K2SO4, K3PO4, or KNO3, then KOH will be produced in the cathode compartment and H2SO4, H3PO4, or HNO3, respectively, will be produced simultaneously in the anode compartment.

[0203] Thus, in an embodiment, the present disclosure relates to a membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in the anode compartment; a cathode comprising a GDE-1 as described herein positioned to extend within the interior of the membrane electrolysis cell and positioned in the cathode compartment; a cation exchange membrane interposed between the anode compartment and the catalyst layer of the gas diffusion electrode, the cation exchange membrane being configured to exchange ions received from the anode to an opposed surface of the cation exchange membrane; an inlet through which the salt-containing solution is received into the anode compartment; a gas inlet through which a gas comprising O2is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product of the salt solution is removed from an interior of the membrane electrolysis cell.

[0204] In another embodiment, the present disclosure relates to a process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in the immediately preceding paragraph, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the anode compartment; the positive salt ions migrate through the cation exchange membrane to the opposed surface of the cation exchange membrane into the cathode compartment; the gas comprising O2is reduced at the cathode to form OH-; the OH- ions combine with the positive salt ions to produce the base product; and the base product is removed from the cathode compartment. Anion Exchange Membrane (AEM)

[0205] An anion exchange membrane (AEM) refers to a membrane permeable to anions. The AEM comprises a polymer having multiple positively charged cationic groups bound to at least a portion of a polymeric backbone. The cationic functional groups may be bound via an extended side chain or directly onto the backbone.

[0206] Non-limiting examples of a polymer backbone of the anion exchange membrane include a polyalkylene such as a polyethylene (PE); a polyfluorene (PFN), a poly(arylene ether) (PAE); a polysulfone, poly(arylene ether sulfone) (PAES), a polyetherketone (PEK), a polyetherimide (PEI), a poly(ether oxadiazole), a poly(phenylene oxide) (PPO); a poly(vinyl benzyl) (PVB); a polyphenylene (PPN); a perfluoro (PF); a polybenzimidazole (PBI); a polystyrene (PS); or a polyphosphazene.

[0207] Non-limiting examples of the cationic functional group include a primary, secondary, tertiary or quaternary ammonium; a heterocyclic cation such as an imidazolium or a pyridinium; a guanidinium; a phosphonium; a sulfonium; and a metal cation.

[0208] Non-limiting examples of the anion exchange membrane include: (10a) FumasepTMFAA AEMs (e.g. FAA, FAA-3-20, FAA-3-25, FAA-3-30, FAA-3-50, FAA-3-PE-30, FAA-3-PK-75, FAA-3-PK-130, FAA-3-PK-150), (10b) FumasepTMFAB AEMs (e.g. FAB-PK-75, FAB-PK-130), (10c) FumasepTMFAD AEMs (e.g. FAD-55, FAD-PET-75), (10d) FumasepTMFAM AEMs (e.g. FAM), (10e) FumasepTMFAAM AEMs (e.g. FAAM-10, FAAM-15, FAAM-20, FAAM-40, FAAM-PK-75), (10f) FumasepTMFAP AEMs (e.g. FAP-330, FAP-450, FAP-330-PE, FAP-330-PE, FAP-420-PE, FAP-375-PP), (10g) FumasepTMFAPQ AEMs (e.g. FAPQ-330, FAPQ-8130-PK, FAPQ-375-PP), (10h) FumasepTMFAS AEMs (e.g. FAS-50, FAS-30, FAS-PET-75, FAS-PE-130), (10i) NeoseptaTMAEMs (e.g. ACN, ACS, AFN, AFX, AHA, AHO, AID, AMX, ASE, AXP-D), (10j) ORIONTMAEMs (e.g. TM1, CMX), (10k) Xergy XionTMPentionTMAEMs (e.g. Pention-AEM-18-05, Pention-AEM-18-10, Pention-AEM-18-20, Pention-AEM-18-30, Pention-AEM-35-05,Pention-AEM-35-10, Pention-AEM-35-20, Pention-AEM-35-30, Pention-AEM-72-05, Pention-AEM-72-10, Pention-AEM-72-20, Pention-AEM-72-30), (10l) PiperIONTMAEMs (e.g. PiperION Anion Exchange Membrane - 15 microns, PiperION Anion Exchange Membrane - 20 microns, PiperION Anion Exchange Membrane - 40 microns, PiperION Anion Exchange Membrane - 60 microns, PiperION Anion Exchange Membrane - 80 microns), (10m) RALEXTMAEMs (e.g. AMHPES, AMHPP), (10n) SELEMIONTMAEMs (e.g. AAV, AAVN, AHO, AMT, AMV, AMVN, ASV, ASVN, DSV, DSVN), (10o) Sustainion® AEMs (e.g. B22-50, E28-50, E30-50, X37-50, X37-60, X37-FA, X37-T, X37-TZ), and (10p) Ionomr AEMs (e.g. Aemion). Cation Exchange Membrane (CEM)

[0209] A cation exchange membrane (CEM) refers to a membrane permeable to cations. In an embodiment, the CEM may be a monovalent cation selective membrane. In another embodiment, the CEM may be a lithium selective membrane.

[0210] The CEM may comprise a polymer having multiple negatively charged anionic groups bound to at least a portion of a polymeric backbone. The anionic functional groups may be bound via an extended side chain or directly onto the backbone.

[0211] Non-limiting examples of a polymer backbone of the cation exchange membrane include a polyalkylene such as a polyethylene (PE) or a polypropylene; a polyfluorene (PFN), a poly(arylene ether) (PAE); a polysulfone, poly(arylene ether sulfone) (PAES), a polyetherketone (PEK), a polyetherimide (PEI), a poly(ether oxadiazole), a poly(phenylene oxide) (PPO); a poly(vinyl benzyl) (PVB); a polyphenylene (PPN); a perfluoro (PF); a polybenzimidazole (PBI); a polystyrene (PS); or a polyphosphazene.

[0212] Non-limiting examples of the anionic functional group include a sulfonate such as a perfluorosulfonate; a carboxylate; a phosphonate; and a phenolate anion.

[0213] Non-limiting examples of the cation exchange membrane include: (11a) Aquivion® CEMs (e.g. E87-05S, E98-05S, E98-09S, E98-15S), (11b) FumasepTMCEMs (e.g. F-930-RFD, F-1075-PK, F-1850, F-10120, F-10120-PK, F-10150-PF, F-10270-PTFE-e, FS-720, FS-950, FS-990-PK, FS-9100-PK, FKB, FKB-PK-130, FKD-PET-75, FKD-PK-75, FKE-50, FKL-PK-130, FKM, FKS-30, FKS-50, FKS-PET-75, FKS-PET-130), (11c) FumapemTMCEMs (e.g. F-14100, F-930, F-930-RFS, FS-715-RFS, FS-930, FS-930-RFS, F-950), (11d) NafionTMCEMs (e.g. N115, N117, N324, N417, N424, N438, N551, N1110), (11e) NeoseptaTMCEMs (e.g. CMB, CMX, CSE, CXP-S), (11f) SELEMIONTMCEMs (e.g. CMD, CMF, CMTE, CMV, CMVN, CSO), and (11g) Exergy XionTMCEMS (e.g. PEM-Nafion-1000-05, PEM-Nafion-1000-10, PEM-Nafion-1000-20, PEM-Nafion-1000-30, PEM-Nafion-1000-50, PEM-Nafion-1100-05, PEM-Nafion-1100-10, PEM-Nafion-1100-20, PEM-Nafion-1100-30, PEM-Nafion-1100-50, PEM-Aquivion-720-05, PEM-Aquivion-720-10, PEM-Aquivion-720-20, PEM-Aquivion-720-30, PEM-Aquivion-720-50, PEM-Aquivion-830-05, PEM-Aquivion-830-10, PEM-Aquivion-830-20, PEM-Aquivion-830-30, and PEM-Aquivion-830-50), (11h) IonomrTMCEMs (e.g. Permion).

[0214] If the salt solution to be processed in the membrane electrolysis cell comprises a lithium salt, the CEM in which the lithium ion migrates through may be (11i) lithium selective. Non-limiting examples of the CEM being a lithium selective membrane include the membranes described in WO2021026607 and WO2022173852, the contents of which are incorporated herein by reference.

[0215] Various particular embodiments of the membrane electrolysis cells of the present disclosure include membrane electrolysis cells, each as defined in the following rows, wherein each entry is a group number as defined above:-compartment membrane electrolysis cell 2-Compartment GDE CEM MEC Embodiment 1 1-896 or 1a-896a (11a) 2 1-896 or 1a-896a (11b) 3 1-896 or 1a-896a (11c) 4 1-896 or 1a-896a (11d) 5 1-896 or 1a-896a (11e) 6 1-896 or 1a-896a (11f) 7 1-896 or 1a-896a (11g) 8 1-896 or 1a-896a (11h) 9 1-896 or 1a-896a (11i)-compartment membrane electrolysis cell 3-Compartment MEC GDE AEM CEM Embodiment 1 1-896 or 1a-896a (10a) (11a) 2 1-896 or 1a-896a (10a) (11b) 3 1-896 or 1a-896a (10a) (11c) 4 1-896 or 1a-896a (10a) (11d) 5 1-896 or 1a-896a (10a) (11e) 6 1-896 or 1a-896a (10a) (11f) 7 1-896 or 1a-896a (10a) (11g) 8 1-896 or 1a-896a (10a) (11h) 9 1-896 or 1a-896a (10a) (11i) 10 1-896 or 1a-896a (10b) (11a) 11 1-896 or 1a-896a (10b) (11b) 12 1-896 or 1a-896a (10b) (11c) 13 1-896 or 1a-896a (10b) (11d) 14 1-896 or 1a-896a (10b) (11e) 15 1-896 or 1a-896a (10b) (11f) 16 1-896 or 1a-896a (10b) (11g) 17 1-896 or 1a-896a (10b) (11h) 18 1-896 or 1a-896a (10b) (11i) 19 1-896 or 1a-896a (10h) (11a) 20 1-896 or 1a-896a (10h) (11b) 21 1-896 or 1a-896a (10h) (11c) 22 1-896 or 1a-896a (10h) (11d) 23 1-896 or 1a-896a (10h) (11e)3-Compartment MEC GDE AEM CEM Embodiment 24 1-896 or 1a-896a (10h) (11f) 25 1-896 or 1a-896a (10h) (11g) 26 1-896 or 1a-896a (10h) (11h) 27 1-896 or 1a-896a (10h) (11i) 28 1-896 or 1a-896a (10i) (11a) 29 1-896 or 1a-896a (10i) (11b) 30 1-896 or 1a-896a (10i) (11c) 31 1-896 or 1a-896a (10i) (11d) 32 1-896 or 1a-896a (10i) (11e) 33 1-896 or 1a-896a (10i) (11f) 34 1-896 or 1a-896a (10i) (11g) 35 1-896 or 1a-896a (10i) (11h) 36 1-896 or 1a-896a (10i) (11i) 37 1-896 or 1a-896a (10n) (11a) 38 1-896 or 1a-896a (10n) (11b) 39 1-896 or 1a-896a (10n) (11c) 40 1-896 or 1a-896a (10n) (11d) 41 1-896 or 1a-896a (10n) (11e) 42 1-896 or 1a-896a (10n) (11f) 43 1-896 or 1a-896a (10n) (11g) 44 1-896 or 1a-896a (10n) (11h) 45 1-896 or 1a-896a (10n) (11i) 46 1-896 or 1a-896a (10p) (11a) 47 1-896 or 1a-896a (10p) (11b) 48 1-896 or 1a-896a (10p) (11c) 49 1-896 or 1a-896a (10p) (11d) 50 1-896 or 1a-896a (10p) (11e) 51 1-896 or 1a-896a (10p) (11f) 52 1-896 or 1a-896a (10p) (11g) 53 1-896 or 1a-896a (10p) (11h) 54 1-896 or 1a-896a (10p) (11i)-compartment membrane electrolysis cell 4-Compartment MEC GDE 1 AEM CEM 2 AEM Embodiment 1 1-896 or 1a-896a (10a) (11a) (10a) 2 1-896 or 1a-896a (10a) (11b) (10a)-Compartment MEC GDE 1 AEM CEM 2 AEM Embodiment 3 1-896 or 1a-896a (10a) (11c) (10a) 4 1-896 or 1a-896a (10a) (11d) (10a) 5 1-896 or 1a-896a (10a) (11e) (10a) 6 1-896 or 1a-896a (10a) (11f) (10a) 7 1-896 or 1a-896a (10a) (11g) (10a) 8 1-896 or 1a-896a (10a) (11h) (10a) 9 1-896 or 1a-896a (10a) (11i) (10a) 10 1-896 or 1a-896a (10a) (11a) (10b) 11 1-896 or 1a-896a (10a) (11b) (10b) 12 1-896 or 1a-896a (10a) (11c) (10b) 13 1-896 or 1a-896a (10a) (11d) (10b) 14 1-896 or 1a-896a (10a) (11e) (10b) 15 1-896 or 1a-896a (10a) (11f) (10b) 16 1-896 or 1a-896a (10a) (11g) (10b) 17 1-896 or 1a-896a (10a) (11h) (10b) 18 1-896 or 1a-896a (10a) (11i) (10b) 19 1-896 or 1a-896a (10b) (11a) (10b) 20 1-896 or 1a-896a (10b) (11b) (10b) 21 1-896 or 1a-896a (10b) (11c) (10b) 22 1-896 or 1a-896a (10b) (11d) (10b) 23 1-896 or 1a-896a (10b) (11e) (10b) 24 1-896 or 1a-896a (10b) (11f) (10b) 25 1-896 or 1a-896a (10b) (11g) (10b) 26 1-896 or 1a-896a (10b) (11h) (10b) 27 1-896 or 1a-896a (10b) (11i) (10b) 28 1-896 or 1a-896a (10h) (11a) (10h) 29 1-896 or 1a-896a (10h) (11b) (10h) 30 1-896 or 1a-896a (10h) (11c) (10h) 31 1-896 or 1a-896a (10h) (11d) (10h) 32 1-896 or 1a-896a (10h) (11e) (10h) 33 1-896 or 1a-896a (10h) (11f) (10h) 34 1-896 or 1a-896a (10h) (11g) (10h) 35 1-896 or 1a-896a (10h) (11h) (10h) 36 1-896 or 1a-896a (10h) (11i) (10h) 37 1-896 or 1a-896a (10i) (11a) (10i) 38 1-896 or 1a-896a (10i) (11b) (10i) 39 1-896 or 1a-896a (10i) (11c) (10i) 40 1-896 or 1a-896a (10i) (11d) (10i)-Compartment MEC GDE 1 AEM CEM 2 AEM Embodiment 41 1-896 or 1a-896a (10i) (11e) (10i) 42 1-896 or 1a-896a (10i) (11f) (10i) 43 1-896 or 1a-896a (10i) (11g) (10i) 44 1-896 or 1a-896a (10i) (11h) (10i) 45 1-896 or 1a-896a (10i) (11i) (10i) 46 1-896 or 1a-896a (10n) (11a) (10n) 47 1-896 or 1a-896a (10n) (11b) (10n) 48 1-896 or 1a-896a (10n) (11c) (10n) 49 1-896 or 1a-896a (10n) (11d) (10n) 50 1-896 or 1a-896a (10n) (11e) (10n) 51 1-896 or 1a-896a (10n) (11f) (10n) 52 1-896 or 1a-896a (10n) (11g) (10n) 53 1-896 or 1a-896a (10n) (11h) (10n) 54 1-896 or 1a-896a (10n) (11i) (10n) 55 1-896 or 1a-896a (10p) (11a) (10p) 56 1-896 or 1a-896a (10p) (11b) (10p) 57 1-896 or 1a-896a (10p) (11c) (10p) 58 1-896 or 1a-896a (10p) (11d) (10p) 59 1-896 or 1a-896a (10p) (11e) (10p) 60 1-896 or 1a-896a (10p) (11f) (10p) 61 1-896 or 1a-896a (10p) (11g) (10p) 62 1-896 or 1a-896a (10p) (11h) (10p) 63 1-896 or 1a-896a (10p) (11i) (10p) 64 1-896 or 1a-896a (10p) (11d) (10a) 65 1-896 or 1a-896a (10p) (11d) (10b) 66 1-896 or 1a-896a (10p) (11d) (10c) 67 1-896 or 1a-896a (10p) (11d) (10d) 68 1-896 or 1a-896a (10p) (11d) (10e) 69 1-896 or 1a-896a (10p) (11d) (10f) 70 1-896 or 1a-896a (10p) (11d) (10g) 71 1-896 or 1a-896a (10p) (11d) (10h) 72 1-896 or 1a-896a (10p) (11d) (10i) 73 1-896 or 1a-896a (10p) (11d) (10j) 74 1-896 or 1a-896a (10p) (11d) (10k) 75 1-896 or 1a-896a (10p) (11d) (10l) 76 1-896 or 1a-896a (10p) (11d) (10m) 77 1-896 or 1a-896a (10p) (11d) (10n) 78 1-896 or 1a-896a (10p) (11d) (10o)-compartment membrane electrolysis cell 5-Compartment MEC GDE 1 AEM 1 CEM 2 AEM 2 CEM Embodiment 1 1-896 or 1a-896a (10a) (11a) (10a) (11a) 2 1-896 or 1a-896a (10a) (11b) (10a) (11b) 3 1-896 or 1a-896a (10a) (11c) (10a) (11c) 4 1-896 or 1a-896a (10a) (11d) (10a) (11d) 5 1-896 or 1a-896a (10a) (11e) (10a) (11e) 6 1-896 or 1a-896a (10a) (11f) (10a) (11f) 7 1-896 or 1a-896a (10a) (11g) (10a) (11g) 8 1-896 or 1a-896a (10a) (11h) (10a) (11h) 9 1-896 or 1a-896a (10b) (11a) (10b) (11a) 10 1-896 or 1a-896a (10b) (11b) (10b) (11b) 11 1-896 or 1a-896a (10b) (11c) (10b) (11c) 12 1-896 or 1a-896a (10b) (11d) (10b) (11d) 13 1-896 or 1a-896a (10b) (11e) (10b) (11e) 14 1-896 or 1a-896a (10b) (11f) (10b) (11f) 15 1-896 or 1a-896a (10b) (11g) (10b) (11g) 16 1-896 or 1a-896a (10b) (11h) (10b) (11h) 17 1-896 or 1a-896a (10c) (11a) (10c) (11a) 18 1-896 or 1a-896a (10c) (11b) (10c) (11b) 19 1-896 or 1a-896a (10c) (11c) (10c) (11c) 20 1-896 or 1a-896a (10c) (11d) (10c) (11d) 21 1-896 or 1a-896a (10c) (11e) (10c) (11e) 22 1-896 or 1a-896a (10c) (11f) (10c) (11f) 23 1-896 or 1a-896a (10c) (11g) (10c) (11g) 24 1-896 or 1a-896a (10c) (11h) (10c) (11h) 25 1-896 or 1a-896a (10d) (11a) (10d) (11a) 26 1-896 or 1a-896a (10d) (11b) (10d) (11b) 27 1-896 or 1a-896a (10d) (11c) (10d) (11c) 28 1-896 or 1a-896a (10d) (11d) (10d) (11d) 29 1-896 or 1a-896a (10d) (11e) (10d) (11e) 30 1-896 or 1a-896a (10d) (11f) (10d) (11f) 31 1-896 or 1a-896a (10d) (11g) (10d) (11g) 32 1-896 or 1a-896a (10d) (11h) (10d) (11h) 33 1-896 or 1a-896a (10e) (11a) (10e) (11a) 34 1-896 or 1a-896a (10e) (11b) (10e) (11b) 35 1-896 or 1a-896a (10e) (11c) (10e) (11c) 36 1-896 or 1a-896a (10e) (11d) (10e) (11d) 37 1-896 or 1a-896a (10e) (11e) (10e) (11e)-Compartment MEC GDE 1 AEM 1 CEM 2 AEM 2 CEM Embodiment 38 1-896 or 1a-896a (10e) (11f) (10e) (11f) 39 1-896 or 1a-896a (10e) (11g) (10e) (11g) 40 1-896 or 1a-896a (10e) (11h) (10e) (11h) 41 1-896 or 1a-896a (10f) (11a) (10f) (11a) 42 1-896 or 1a-896a (10f) (11b) (10f) (11b) 43 1-896 or 1a-896a (10f) (11c) (10f) (11c) 44 1-896 or 1a-896a (10f) (11d) (10f) (11d) 45 1-896 or 1a-896a (10f) (11e) (10f) (11e) 46 1-896 or 1a-896a (10f) (11f) (10f) (11f) 47 1-896 or 1a-896a (10f) (11g) (10f) (11g) 48 1-896 or 1a-896a (10f) (11h) (10f) (11h) 49 1-896 or 1a-896a (10g) (11a) (10g) (11a) 50 1-896 or 1a-896a (10g) (11b) (10g) (11b) 51 1-896 or 1a-896a (10g) (11c) (10g) (11c) 52 1-896 or 1a-896a (10g) (11d) (10g) (11d) 53 1-896 or 1a-896a (10g) (11e) (10g) (11e) 54 1-896 or 1a-896a (10g) (11f) (10g) (11f) 55 1-896 or 1a-896a (10g) (11g) (10g) (11g) 56 1-896 or 1a-896a (10g) (11h) (10g) (11h) 57 1-896 or 1a-896a (10h) (11a) (10h) (11a) 58 1-896 or 1a-896a (10h) (11b) (10h) (11b) 59 1-896 or 1a-896a (10h) (11c) (10h) (11c) 60 1-896 or 1a-896a (10h) (11d) (10h) (11d) 61 1-896 or 1a-896a (10h) (11e) (10h) (11e) 62 1-896 or 1a-896a (10h) (11f) (10h) (11f) 63 1-896 or 1a-896a (10h) (11g) (10h) (11g) 64 1-896 or 1a-896a (10h) (11h) (10h) (11h) 65 1-896 or 1a-896a (10i) (11a) (10i) (11a) 66 1-896 or 1a-896a (10i) (11b) (10i) (11b) 67 1-896 or 1a-896a (10i) (11c) (10i) (11c) 68 1-896 or 1a-896a (10i) (11d) (10i) (11d) 69 1-896 or 1a-896a (10i) (11e) (10i) (11e) 70 1-896 or 1a-896a (10i) (11f) (10i) (11f) 71 1-896 or 1a-896a (10i) (11g) (10i) (11g) 72 1-896 or 1a-896a (10i) (11h) (10i) (11h) 73 1-896 or 1a-896a (10j) (11a) (10j) (11a) 74 1-896 or 1a-896a (10j) (11b) (10j) (11b) 75 1-896 or 1a-896a (10j) (11c) (10j) (11c) 76 1-896 or 1a-896a (10j) (11d) (10j) (11d)-Compartment MEC GDE 1 AEM 1 CEM 2 AEM 2 CEM Embodiment 77 1-896 or 1a-896a (10j) (11e) (10j) (11e) 78 1-896 or 1a-896a (10j) (11f) (10j) (11f) 79 1-896 or 1a-896a (10j) (11g) (10j) (11g) 80 1-896 or 1a-896a (10j) (11h) (10j) (11h) 81 1-896 or 1a-896a (10k) (11a) (10k) (11a) 82 1-896 or 1a-896a (10k) (11b) (10k) (11b) 83 1-896 or 1a-896a (10k) (11c) (10k) (11c) 84 1-896 or 1a-896a (10k) (11d) (10k) (11d) 85 1-896 or 1a-896a (10k) (11e) (10k) (11e) 86 1-896 or 1a-896a (10k) (11f) (10k) (11f) 87 1-896 or 1a-896a (10k) (11g) (10k) (11g) 88 1-896 or 1a-896a (10k) (11h) (10k) (11h) 89 1-896 or 1a-896a (10l) (11a) (10l) (11a) 90 1-896 or 1a-896a (10l) (11b) (10l) (11b) 91 1-896 or 1a-896a (10l) (11c) (10l) (11c) 92 1-896 or 1a-896a (10l) (11d) (10l) (11d) 93 1-896 or 1a-896a (10l) (11e) (10l) (11e) 94 1-896 or 1a-896a (10l) (11f) (10l) (11f) 95 1-896 or 1a-896a (10l) (11g) (10l) (11g) 96 1-896 or 1a-896a (10l) (11h) (10l) (11h) 97 1-896 or 1a-896a (10m) (11a) (10m) (11a) 98 1-896 or 1a-896a (10m) (11b) (10m) (11b) 99 1-896 or 1a-896a (10m) (11c) (10m) (11c) 100 1-896 or 1a-896a (10m) (11d) (10m) (11d) 101 1-896 or 1a-896a (10m) (11e) (10m) (11e) 102 1-896 or 1a-896a (10m) (11f) (10m) (11f) 103 1-896 or 1a-896a (10m) (11g) (10m) (11g) 104 1-896 or 1a-896a (10m) (11h) (10m) (11h) 105 1-896 or 1a-896a (10n) (11a) (10n) (11a) 106 1-896 or 1a-896a (10n) (11b) (10n) (11b) 107 1-896 or 1a-896a (10n) (11c) (10n) (11c) 108 1-896 or 1a-896a (10n) (11d) (10n) (11d) 109 1-896 or 1a-896a (10n) (11e) (10n) (11e) 110 1-896 or 1a-896a (10n) (11f) (10n) (11f) 111 1-896 or 1a-896a (10n) (11g) (10n) (11g) 112 1-896 or 1a-896a (10n) (11h) (10n) (11h) 113 1-896 or 1a-896a (10o) (11a) (10o) (11a) 114 1-896 or 1a-896a (10o) (11b) (10o) (11b) 115 1-896 or 1a-896a (10o) (11c) (10o) (11c)-Compartment MEC GDE 1 AEM 1 CEM 2 AEM 2 CEM Embodiment 116 1-896 or 1a-896a (10o) (11d) (10o) (11d) 117 1-896 or 1a-896a (10o) (11e) (10o) (11e) 118 1-896 or 1a-896a (10o) (11f) (10o) (11f) 119 1-896 or 1a-896a (10o) (11g) (10o) (11g) 120 1-896 or 1a-896a (10o) (11h) (10o) (11h) 121 1-896 or 1a-896a (10p) (11a) (10p) (11a) 122 1-896 or 1a-896a (10p) (11b) (10p) (11b) 123 1-896 or 1a-896a (10p) (11c) (10p) (11c) 124 1-896 or 1a-896a (10p) (11d) (10p) (11d) 125 1-896 or 1a-896a (10p) (11e) (10p) (11e) 126 1-896 or 1a-896a (10p) (11f) (10p) (11f) 127 1-896 or 1a-896a (10p) (11g) (10p) (11g) 128 1-896 or 1a-896a (10p) (11h) (10p) (11h) 129 1-896 or 1a-896a (10a) (11a) (10b) (11a) 130 1-896 or 1a-896a (10a) (11b) (10b) (11b) 131 1-896 or 1a-896a (10a) (11c) (10b) (11c) 132 1-896 or 1a-896a (10a) (11d) (10b) (11d) 133 1-896 or 1a-896a (10a) (11e) (10b) (11e) 134 1-896 or 1a-896a (10a) (11f) (10b) (11f) 135 1-896 or 1a-896a (10a) (11g) (10b) (11g) 136 1-896 or 1a-896a (10a) (11h) (10b) (11h) 137 1-896 or 1a-896a (10a) (11i) (10a) (11a) 138 1-896 or 1a-896a (10a) (11i) (10a) (11b) 139 1-896 or 1a-896a (10a) (11i) (10a) (11c) 140 1-896 or 1a-896a (10a) (11i) (10a) (11d) 141 1-896 or 1a-896a (10a) (11i) (10a) (11e) 142 1-896 or 1a-896a (10a) (11i) (10a) (11f) 143 1-896 or 1a-896a (10a) (11i) (10a) (11g) 144 1-896 or 1a-896a (10a) (11i) (10a) (11h) 145 1-896 or 1a-896a (10b) (11i) (10b) (11a) 146 1-896 or 1a-896a (10b) (11i) (10b) (11b) 147 1-896 or 1a-896a (10b) (11i) (10b) (11c) 148 1-896 or 1a-896a (10b) (11i) (10b) (11d) 149 1-896 or 1a-896a (10b) (11i) (10b) (11e) 150 1-896 or 1a-896a (10b) (11i) (10b) (11f) 151 1-896 or 1a-896a (10b) (11i) (10b) (11g) 152 1-896 or 1a-896a (10b) (11i) (10b) (11h) 153 1-896 or 1a-896a (10n) (11i) (10n) (11a) 154 1-896 or 1a-896a (10n) (11i) (10n) (11b)5-Compartment MEC GDE 1 AEM 1 CEM 2 AEM 2 CEM Embodiment 155 1-896 or 1a-896a (10n) (11i) (10n) (11c) 156 1-896 or 1a-896a (10n) (11i) (10n) (11d) 157 1-896 or 1a-896a (10n) (11i) (10n) (11e) 158 1-896 or 1a-896a (10n) (11i) (10n) (11f) 159 1-896 or 1a-896a (10n) (11i) (10n) (11g) 160 1-896 or 1a-896a (10n) (11i) (10n) (11h) 161 1-896 or 1a-896a (10p) (11i) (10p) (11a) 162 1-896 or 1a-896a (10p) (11i) (10p) (11b) 163 1-896 or 1a-896a (10p) (11i) (10p) (11c) 164 1-896 or 1a-896a (10p) (11i) (10p) (11d) 165 1-896 or 1a-896a (10p) (11i) (10p) (11e) 166 1-896 or 1a-896a (10p) (11i) (10p) (11f) 167 1-896 or 1a-896a (10p) (11i) (10p) (11g) 168 1-896 or 1a-896a (10p) (11i) (10p) (11h) 169 1-896 or 1a-896a (10p) (11d) (10a) (11d) 170 1-896 or 1a-896a (10p) (11d) (10b) (11d) 171 1-896 or 1a-896a (10p) (11d) (10c) (11d) 172 1-896 or 1a-896a (10p) (11d) (10d) (11d) 173 1-896 or 1a-896a (10p) (11d) (10e) (11d) 174 1-896 or 1a-896a (10p) (11d) (10f) (11d) 175 1-896 or 1a-896a (10p) (11d) (10g) (11d) 176 1-896 or 1a-896a (10p) (11d) (10h) (11d) 177 1-896 or 1a-896a (10p) (11d) (10i) (11d) 178 1-896 or 1a-896a (10p) (11d) (10j) (11d) 179 1-896 or 1a-896a (10p) (11d) (10k) (11d) 180 1-896 or 1a-896a (10p) (11d) (10l) (11d) 181 1-896 or 1a-896a (10p) (11d) (10m) (11d) 182 1-896 or 1a-896a (10p) (11d) (10n) (11d) 183 1-896 or 1a-896a (10p) (11d) (10o) (11d)

[0216] The flow rate of the salt solution in the membrane electrolysis cells described herein may be between 0.5 and 5 Litres / min, between 0.5 and 4.8 Litres / min, between 0.5 and 4.6 Litres / min, between 0.5 and 4.4 Litres / min, between 0.5 and 4.2 Litres / min, between 0.5 and 4.0 Litres / min, between 0.5 and 3.8 Litres / min, between 0.5 and 3.6 Litres / min, between 0.5 and 3.4 Litres / min, between 0.5 and 3.2 Litres / min, between 0.5 and 3.0 Litres / min, between 0.5 and 2.8 Litres / min, between 0.5 and 2.6 Litres / min, between 0.5 and 2.4 Litres / min, between 0.5 and 2.2 Litres / min, between 0.5 and 2.0 Litres / min, between 0.5 and 1.8 Litres / min, between 0.5 and 1.6 Litres / min, between0.5 and 1.4 Litres / min, between 0.5 and 1.2 Litres / min, between 0.5 and 1.0 Litres / min, between 1.0 and 3.0 Litres / min, between 1.2 and 2.8 Litres / min, between 1.4 and 2.6 Litres / min, between 1.6 and 2.4 Litres / min, or between 1.8 and 2.2 Litres / min.

[0217] The flow rate of the gas comprising oxygen in the membrane electrolysis cells described herein may be between 5 and 25 Litres / min, between 5 and 23 Litres / min, between 5 and 21 Litres / min, between 5 and 19 Litres / min, between 5 and 17 Litres / min, between 5 and 15 Litres / min, between 5 and 13 Litres / min, between 5 and 11 Litres / min, between 5 and 9 Litres / min, between 5 and 7 Litres / min, between 7 and 25 Litres / min, between 9 and 25 Litres / min, between 11 and 25 Litres / min, between 13 and 25 Litres / min, between 15 and 25 Litres / min, between 17 and 25 Litres / min, between 19 and 25 Litres / min, between 21 and 25 Litres / min, between 23 and 25 Litres / min, between 7 and 23 Litres / min, between 9 and 21 Litres / min, between 11 and 19 Litres / min, or between 13 and 17 Litres / min.

[0218] The temperature of the salt solution in the membrane electrolysis cells described herein may be between 40 and 70oC, between 40 and 65oC, between 40 and 60oC, between 40 and 55oC, between 40 and 50oC, between 40 and 45oC, between 45 and 70oC, between 50 and 70oC, between 55 and 70oC, between 60 and 70oC, between 65 and 70oC, between 45 and 65oC, or between 50 and 60oC. Incorporation of Membrane Electrolysis Cell Comprising Gas Diffusion Electrodes into Lithium Recovery Processes

[0219] A salar brine lithium recovery process which may utilize the membrane electrolysis cells as described herein, together with the GDEs as described herein, is shown in FIG. 9. As can be seen, the sodium chloride salt extracted from the evaporation stage in lithium brine recovery process is fed into the membrane electrolysis cell as the feed brine. The feed brine then undergoes a depletion process as it passes through the cell. The depletion is a result of the Na+ and OH- ions migrating out of the salt depletion compartment into a base build up compartment and an acid build up compartment, respectively.

[0220] The ions that migrate out of the salt depletion compartment depend on what ionic species are in the feed brine that is fed to the membrane electrolysis cell. Hence, the desalinated water removed from the salt depletion compartment can be re-concentrated and therefore recycled as feed brine using the readily available salt (NaCl) stockpile from the salts that are precipitated from the salar lake evaporation ponds. The concentration of feed brineplays an important role in providing the mass transfer of the feed brine as well as supplying ions for acid and base generation. Although the membrane cell can be operated at feed brine concentrations as low as 0.1 wt% of salt, it is beneficial to operate at the maximum available feed brine concentrations.

[0221] The concentration of product acid and base that are removed from the acid and base build up compartments, respectively, may be adjusted according to the requirements of each particular process. Caustic soda (NaOH) concentrations in the range of 5-20 wt% may be achieved using the membrane electrolysis cells, together with the GDEs, as described herein. As shown in FIG.9, typical uses of the NaOH produced in the membrane cell in a salar brine lithium recovery operation include, but are not necessarily limited to: ^ Neutralization and pH adjustment after the solvent extraction process to recycle the solvent; ^ Provide alkalinity for precipitation and hardness removal; ^ Regeneration of the ion exchange resins used for hardness and metal removal; ^ Conversion of lithium carbonate into lithium hydroxide through caustization process.

[0222] All of the above-mentioned processes require caustic (NaOH) concentrations in the range of 5-20 wt% which is within the range achievable by the membrane electrolysis cell.

[0223] Non-limiting examples of typical uses of the hydrochloric acid that can be produced by the membrane electrolysis cell during a lithium brine recovery process is as follows: ^ Adjustment of pH to remove boron during the solvent extraction process; ^ Regeneration of the ion exchange resins used for hardness and metal removal; ^ Conversion of lithium carbonate into lithium chloride.

[0224] A concentration of hydrochloric acid for the above-mentioned applications is in the range of 4-12 wt% which is achievable by the membrane electrolysis cell.

[0225] A lithium rock mining operation process which incorporates the membrane electrolysis cells, together with the GDEs as described herein, is shown in FIG. 10. As can be seen, the sodium sulfate (Na2SO4) salt which is the largest by-product of a lithium rock mining operation can be used as a feed brine to the membrane electrolysis cell. As shown in FIG. 10, feeding Na2SO4to the membrane electrolysis cell will produce NaOH and H2SO4as the base and acid, respectively. These can be recycled and used as reagents in the lithium recovery process.

[0226] Sulfuric acid (H2SO4) is the main reagent necessary for extracting the lithium from the ore during the acid roasting process. As shown in FIG. 10, this chemical can be regenerated from the readily available sodium sulfate by-product of the lithium ore hard rock mining operation.

[0227] Likewise, the sodium hydroxide that is produced can be used in a variety of ways in the overall lithium production process. Non-limiting examples of uses of sodium hydroxide during a lithium rock mining operation are as follows: ^ Provide alkalinity for precipitation and hardness removal; ^ Regeneration of the ion exchange resins used for hardness and metal removal; ^ Conversion of lithium sulfate into lithium hydroxide by adding NaOH to the process.

[0228] All above mentioned processes require NaOH concentrations in the range of 5-20 wt.% which is within the range achievable by the membrane electrolysis cell.

[0229] FIG.11 shows a first embodiment of onsite LiOH and HCl generation from LiCl using the membrane electrolysis cells, together with the GDEs, as described herein. In an embodiment (not shown), the membrane electrolysis cell is used to convert LiCl into LiOH in a lithium recovery from a salar brine process. As shown in FIG. 11, the brine feed to the membrane electrolysis cell is a solution of LiCl, which is fed to a salt depletion compartment of the membrane electrolysis cell (not shown). Oxygen gas, which is preferably in the form of air is fed to the cathode. The oxygen or air may optionally be humidified, e.g., by bubbling the gas through water before feeding it to cathode. The air may optionally be purified. As shown, the outputs from the cell are LiOH, which is removed from the base build up compartment (not shown) and HCl, which is removed from the acid build up compartment(not shown). Desalinated water may be optionally removed from the cell, although this stream is not shown in FIG.11. Whether or not desalinated water is removed from the cell depends on the concentration of the feed brine, i.e. the aqueous LiCl solution, as well as the desired concentration of LiOH and HCl that are produced.

[0230] In an analogous manner, water may optionally be fed to the cell, rather than being removed. Whether or not water is fed to the cell depends on the concentration of the feed brine, i.e. the aqueous LiCl solution, as well as the desired concentration of LiOH and HCl that are produced. As shown in FIG. 11, in this embodiment, the HCl can be used to regenerate the ion exchange resins that are used to remove Ca, Mg, Na, and K from the LiCl process stream that enters the cell. The HCl may also be used in the boron removal step to regenerate the ion exchange resin, which is typically after the evaporation / precipitation step near the beginning of the process. The HCl may be used for pH adjustment of the process stream which generates CO2 as shown in FIG. 11. The CO2 can be combined with a portion of the LiOH product stream, thereby producing a stream that comprises LiOH and Li2CO3. The LiOH / Li2CO3 stream can be fed to the precipitation step that removes Ca and Mg, as shown in FIG. 11. Importantly, not all of the LiOH product stream is used in this precipitation step, because the LiOH is the desired product. However, the ability to use the LiOH in this way, reduces significantly the need to buy a base such as NaOH or Na2CO3 to effect the precipitation removal of Ca and Mg.

[0231] As a point of reference, based on a test using 6% LiCl stream used as a brine feed, it takes about 150-250 kWh / m3of LiCl brine to reduce the total salt content to 3% when air is used at the oxygen depolarized cathode (ODC).

[0232] FIG. 12 depicts a second embodiment implementation of the membrane electrochemical cells, together with GDEs as described herein, in the recovery of lithium from a salar brine. In this embodiment, an aqueous LiCl solution is again the brine feed to the membrane electrolysis cell. In this embodiment, like the first embodiment, the membrane electrolysis cell is used to convert LiCl into LiOH. The aqueous solution of LiCl is fed to the salt depletion compartment of the membrane electrolysis cell. Oxygen gas, which is preferably in the form of air, is fed to the cathode. The oxygen or air may optionally be humidified, e.g., by bubbling the gas through water before feeding it to cathode and the air may optionally be purified. As shown, the outputs from the cell are LiOH, which is removed from the base build up compartment (not shown) and HCl, which is removed from the acidbuild up compartment (not shown). As in the first embodiment, desalinated water may be optionally removed from the cell, although this stream is not shown in FIG. 12.

[0233] Whether or not desalinated water is removed from the cell depends on the concentration of the feed brine, i.e. the aqueous LiCl solution, as well as the desired concentration of LiOH and HCl that are produced. In an analogous manner, water may optionally be fed to the cell, rather than being removed. Whether or not water is fed to the cell depends on the concentration of the feed brine, i.e. the aqueous LiCl solution, as well as the desired concentration of LiOH and HCl that are produced. In this embodiment, all of the LiOH that is produced is removed, i.e. there is not a recycle stream comprising LiOH.

[0234] However, the HCl stream as in the first embodiment may be recycled and used in the lithium recovery process. As shown in FIG. 12, the HCl is used to regenerate the ion exchange resins used to remove the Ca and Mg from the process stream just prior to the stream being fed to the membrane electrolysis cell as the feed brine. The HCl produced may also be used to in the removal of the boron B, after the precipitation step to regenerate the ion exchange resin.

[0235] FIG. 13 shows a third embodiment illustrating use of the membrane electrolysis cells, together with the GDEs as described herein, in a lithium production process. In this embodiment of the process, a mixed brine solution comprising both LiCl and NaCl are fed to the membrane electrolysis cell. The cell then produces HCl and a mixed LiOH and NaOH solution. This mixed LiOH and NaOH solution is fed to a crystallization / separation step that produces crystalized LiOH and a mixed solution of NaOH and a lower concentration of LiOH than the mixed LiOH and NaOH solution that was fed to the crystallization / separation step. As can be seen in FIG. 13, the process is similar to that of FIGs. 9 and 11, but utilizes the membrane electrolysis cell into an existing operation to produce LiOH from salar brine. In an alternative embodiment, the membrane electrolysis cell may be applied to another waste or recycle lithium chloride stream produced in a conventional lithium operation that does not have sodium, and could convert the lithium chloride to lithium hydroxide and hydrochloric acid.

[0236] The steps are thus: Step 1: The mixed lithium chloride and sodium chloride stream that is produced from a conventional salar brine processing operation is fed to the membrane electrolysiscell (electrochemical cell) to produce a mixed lithium hydroxide and sodium hydroxide solution. Step 2: The mixed lithium hydroxide and sodium hydroxide are sent to a crystallizer / separator where they are separated due to the large solubility difference between the two salts – the NaOH is much more soluble in water than the LiOH. The crystallization / separation unit may either evaporate and optionally re-condense the water, or may simply effect the precipitation of some of the LiOH by cooling the mixed solution of NaOH and LiOH. The more typical method is simply to evaporate the water. The lithium hydroxide is crystallized while the sodium hydroxide remains in solution. The crystallized lithium hydroxide is ready for market. Step 3: Some lithium hydroxide remains in solution with the sodium hydroxide and is recycled back to the process for use in the precipitation stages. Step 4: Some lithium hydroxide and sodium hydroxide is combined with carbon dioxide to produce a mixed lithium carbonate and sodium carbonate stream which is recycled back to the overall process and used for further precipitation, which can be seen in FIG. 13.

[0237] Taken together, these steps result in a closed or nearly closed loop for sodium hydroxide, sodium carbonate and lithium carbonate by the incorporation of the electrochemical cell (membrane electrolysis cell) into the overall process to recover LiOH from salar brine.

[0238] Turning next to FIG. 14, a fourth embodiment use of the membrane electrolysis cells, together with the GDEs as described herein, in a lithium production process is shown. As shown in FIG. 14, the membrane electrolysis cell is used to convert Li2SO4 to LiOH in a process where lithium is produced from a lithium-containing ore. However, a person having skill in the art can appreciate that the brine feed stream which comprises an aqueous solution of Li2SO4does not necessarily have to be from a lithium ore-based process.

[0239] In certain brine recovery processes it is desirable to convert a Li2SO4solution to a LiOH, and so the membrane electrolysis cell could be used in such a process as well. As shown in FIG. 14, the membrane electrolysis cell uses an aqueous solution of Li2SO4. Also fed to the cell, as in the other embodiments, is a gas stream which comprises oxygen.This stream which preferably is air, is fed to the cathode. The oxygen or air may optionally be humidified, e.g., by bubbling the gas through water before feeding it to cathode and the air may optionally be purified. As shown, the outputs from the cell are LiOH, which is removed from the base build up compartment (not shown) and H2SO4, which is removed from the acid build up compartment (not shown).

[0240] As in the first embodiment and the second embodiment, desalinated water may be optionally removed from the cell, although this stream is not shown in FIG. 14. Whether or not desalinated water is removed from the cell depends on the concentration of the feed brine, i.e. the aqueous Li2SO4 solution, as well as the desired concentration of LiOH and H2SO4that are produced. In an analogous manner, water may optionally be fed to the cell, rather than being removed. Whether or not water is fed to the cell depends on the concentration of the feed brine, i.e. the aqueous Li2SO4solution, as well as the desired concentration of LiOH and H2SO4 that are produced.

[0241] In this embodiment, both the LiOH and the H2SO4 are recycled back into the lithium recovery process, which mitigates at least some of the need to buy additional reagents. Importantly, only a portion of the LiOH is recycled, since of course the LiOH is a desirable end product. The H2SO4is used in the acid roasting step of ore production, in order to produce the Li2SO4 brine solution after the water leaching step. A portion of the LiOH that is produced can be used to precipitate out Ca and Mg from the Li2SO4brine solution after the water leaching step, as shown in FIG. 13.

[0242] FIG. 15 shows an exemplary embodiment of the use of the membrane electrolysis cells, together with the GDEs as described herein, in a closed-loop process in which lithium carbonate (Li2CO3) produced from other methods, for example, lithium carbonate produced from brine operations by precipitation with the use of sodium carbonate or lithium carbonate produced from jadarite (LiNaSiB3O7OH) may be dissolved in hydrochloric acid to produce a lithium chloride solution which is converted to LiOH. The process as shown in FIG. 15 proceeds as follows: Step 1: Lithium carbonate produced from other methods is converted to lithium chloride by dissolution in hydrochloric acid. Step 2: The lithium chloride is processed through the electrochemical cell to produce lithium hydroxide and hydrochloric acid.Step 3: The hydrochloric acid is recycled back for further conversion of lithium carbonate to lithium chloride resulting in a completely or substantially closed loop system.

[0243] Similarly, the process as shown in Fig. 15 could proceed with sulfuric acid in place of hydrochloric acid as follows: Step 1: Lithium carbonate produced from other methods is converted to lithium sulfate by dissolution in sulfuric acid. Step 2: The lithium sulfate is processed through the electrochemical cell to produce lithium hydroxide and sulfuric acid. Step 3: The sulfuric acid is recycled back for further conversion of lithium carbonate to lithium sulfate resulting in a completely or substantially closed loop system.

[0244] As shown in the following two exemplary embodiments (FIGs. 16 and 17), the membrane electrolysis cells, together with the GDEs as described herein, may also be used in lithium recovery processes that incorporate ion exchange resins. These ion exchange resins may be used either directly to produce LiOH, or they may be used to recycle and / or recover other ionic species during the lithium recovery process. The use of the advantages of these embodiments (and all embodiments of the membrane electrolysis cell disclosed herein) are manifold vis-à-vis operational and capital cost savings.

[0245] As discussed above, lithium hydroxide is produced by processing lithium rich brines, such as salar brines, through an extensive process. The water in the brine is allowed to evaporate over a period of 6 to 18 months to concentrate the lithium chloride in the solution to 5 wt.% LiCl or higher and to precipitate out significant sodium, calcium and magnesium salt species, since these are in general less soluble than the LiCl.

[0246] The lithium chloride-rich brine must then be subjected to a variety of purification steps. These purification steps may include for example: boron removal through a solvent or other means, calcium and magnesium removal through the addition of lime (calcium oxide and / or calcium hydroxide) and caustic soda, soda ash and / or sodium bicarbonate or other species, further calcium and magnesium removal through the addition of soda ash, i.e., sodium carbonate Na2CO3. These processes produce a mixed lithium chloride and sodium chloride stream to which additional soda ash is added resulting in theprecipitation of lithium carbonate. The lithium carbonate may then be crystallized. Currently, this crystallized lithium carbonate is often transported to a lithium hydroxide plant where it is converted to lithium hydroxide by adding calcium hydroxide. The lithium hydroxide is then crystallized for sale. There are several process units associated with all these steps and clearly, procuring and maintaining these process units represents significant capital investment as well as on-going operational costs.

[0247] An ion exchange resin selective to adsorption or binding of lithium can be used to eliminate many of these steps to selectively adsorb lithium from the salar brine (or other source) without the need for time-consuming evaporation or removal of boron, calcium, magnesium, etc. For instance, an ion exchange resin for selectively binding lithium and producing lithium chloride by desorbing the lithium from the resin with HCl could be utilized. A membrane electrolysis cell as described herein can convert the lithium chloride to lithium hydroxide and the hydrochloric acid, which would be recycled back to the ion exchange resin, which the desirable lithium hydroxide is collected.

[0248] In another embodiment, an ion exchange resin for selective adsorption of lithium could also be used to produce lithium sulfate by regeneration of the resin with sulfuric acid. Analogously, the lithium sulfate would be fed to the electrolysis cell to produce lithium hydroxide and sulfuric acid. The sulfuric acid would be recycled back to the ion exchange resin to produce more lithium sulfate, while the desirable lithium hydroxide is collected.

[0249] The ion exchange resin would eliminate significant capital and operating expenditures and costs associated with the lithium evaporation ponds and associated downstream transportation.

[0250] Eliminating the evaporation ponds would also conserve water which is lost to the atmosphere during the evaporation step. Producers would be able to pump the lithium-depleted brine back to the salar brine reservoir, which conserves the water which would be evaporated. This feature is critical from both environmental and legal viewpoints. Chile, for example, where most of the world’s lithium brines are located, has strict limits on water usage and the amount of brine lithium producers can pump. The purpose of the regulations is to conserve the scarce water in the Salar desert region of Chile. Therefore, these limits effectively mean that the producers’ production of lithium is limited. However, if the lithium-depleted brine from the ion exchange process is pumped back to the reservoirs,much less net brine is pumped, and the producers can increase their production of lithium without exceeding the governmental limits on the amount of salar brine they can pump or amount of water used in the operation. Use of ion exchange resins in the lithium recovery process would also save time, since the evaporation step is slow. Additionally and importantly, the need to purchase reagents necessary for precipitation of calcium and magnesium would be eliminated.

[0251] The largest cost associated with direct production of lithium with ion exchange resins is with the need to procure HCl which is required to desorb or unbind the lithium ion from the active sites and regenerate the ion-exchange resin. An electrochemical cell as described herein that is capable of converting lithium chloride to lithium hydroxide and hydrochloric acid not only eliminates the need to procure the reagent required for the conversion of lithium chloride to lithium carbonate to lithium hydroxide, but these cells also produce the vital HCl required to extract the lithium from the ion exchange resin. Accordingly, the whole process starting from lithium chloride evaporation to lithium carbonate production and lithium carbonate conversion through to production of lithium hydroxide for use in batteries may be simplified to the use of only an ion exchange resin and an electrochemical cell.

[0252] In addition, another exemplary use of the membrane electrolysis cells in processes utilizing ion exchange resins to directly adsorb lithium from brine is a process where the ion exchange resin is deployed in the desert where the salar brine is pumped, while the membrane electrolysis cell is in a different location. In this exemplary process the ion exchange resin is removed, transported to the location of the membrane electrolysis cell where the ion exchange resin is regenerated with HCl thus producing LiOH. The ion-exchange resin would then be shipped back to the brine site in the desert. Thus, a used ion-exchange resin would move one way and the regenerated ion exchange resin would move the opposite way. Therefore, in any of the exemplary processes shown in FIGs.15, 16, or 17 below, the membrane electrolysis cells, together with the GDEs described herein, could be located in a different location from the ion exchange resin.

[0253] Non-limiting examples of suitable such ion exchange resins are those that selectively binds lithium or another precious metal based on the pH of the solution. For example, the resin may bind lithium in acid but not in alkali, or vice versa. This allows us to be able to regenerate the resin and extract lithium from it. This allows the producers to beable to regenerate the resin and extract lithium from it. The membrane electrolysis cell then produces the appropriate pH solution to remove the bound ion by providing HCl or NaOH. Such ion exchange resins may also include complexed metal resins such as HnMnOnwhere the H is hydrogen, M is a metal species, O is oxygen and n is an integer. Non-limiting examples include LiAlO2, LiCuO2, among others.

[0254] The following two embodiments thus demonstrate how the membrane electrolysis cells, together with the GDEs as described herein, may be incorporated into lithium recovery processes in which an ion exchange resin is used to directly produce LiOH.

[0255] FIG. 16 shows an exemplary embodiment of a use of the membrane electrolysis cell in a lithium production process where an ion exchange resin is used to selectively adsorb Li from a lithium brine. This lithium brine does not have to be a salar brine – it can be a brine from other industrial processes such as produced water from oil and gas operations, or geothermal brines which sometimes have lithium or naturally occurring saline aquifers, or the brine can be derived from a lithium ion battery recycling process. As can be seen in FIG. 16, the membrane electrolysis cell simultaneously produces LiOH, which can be sold, but also produces HCl which is used to remove the Li (as LiCl) from the ion exchange resin, thus regenerating the ion exchange resin. The LiCl is fed to the membrane electrolysis cell to produce the desired LiOH. In an alternative embodiment, lithium sulfate could be produced by using sulfuric acid and producing lithium sulfate which can be used to produce the desired lithium hydroxide in the membrane electrolysis cell. The steps in the process are as follows: Step 1: Lithium containing brine or solution is processed with an ion exchange resin or other adsorbing agent to adsorb lithium out of the brine or solution. Step 2: The lithium containing resin bead or adsorbent is regenerated with hydrochloric acid to produce a lithium chloride solution. The resin or adsorbing agent is regenerated to the proton form by HCl. Alternatively, the resin could be regenerated with sulfuric acid. Step 3: The lithium chloride solution is processed through the electrochemical cell to produce lithium hydroxide and hydrochloric acid. Alternatively, the lithium sulfate solution could be processed through the electrochemical call to produce lithium hydroxide and sulfuric acid.Step 4: The lithium hydroxide is sold to market or otherwise removed from the process while the hydrochloric acid is recycled back to Step 2.

[0256] FIG. 17 shows another exemplary use of the membrane electrolysis cell as disclosed herein in which the lithium-containing brine is subjected to a process in which boron is removed before the brine is sent to the ion exchange resin and then to the membrane electrolysis cell. As shown in FIG.16, in this exemplary embodiment, the process steps after the boron removal are: Step 1: Lithium containing brine or solution is processed with an ion exchange resin or other adsorbing agent to adsorb lithium out of the brine or the solution. Step 2: The lithium-containing ion exchange resin beads or other suitable lithium adsorbent is regenerated with hydrochloric acid to produce a lithium chloride solution. The resin or adsorbing agent is regenerated to the proton form by HCl. Note that a lithium depleted solution may be pumped back to the salar reservoir or pond. As noted above, since there are typically water conservation limits in place, particularly in Chile, regarding the amount of salar brine that may be pumped out of the natural reservoirs, if the depleted solution is sent back to the reservoir, the producer may then produce more lithium without exceeding their legal limit regarding the amount of brine that they can pump. Step 3: The lithium chloride solution is processed through the membrane electrochemical cell disclosed herein to produce lithium hydroxide and hydrochloric acid. Alternatively, lithium sulfate is process through the membrane electrochemical cell to produce lithium hydroxide and sulfuric acid. Step 4: The lithium hydroxide is sold to market or otherwise removed from the process while the hydrochloric acid or sulfuric acid is recycled back to Step 2.

[0257] Note that in the process as shown in FIG. 17, air and electricity are fed to the membrane electrolysis cell. The overall reactions at the anode and cathode of the electrolysis are therefore: Anode: 2H2O # O2+ 4H+ + 4e-Cathode: O2 + 2H2O + 4e- # 4OH-

[0258] As shown in the following exemplary embodiment (FIG. 18), the membrane electrolysis cell may also be used in alkali (e.g. LiOH) recovery processes that incorporate solvent extraction (SX) methods.

[0259] SX methods are used to separate compounds according to their relative solubilities into two immiscible liquid phases - an organic phase and an aqueous phase. The organic phase is added to the aqueous solution to form organic Li+complexes. The Li+complexes (and some residual impurity metals) are transferred to the organic phase. Most impurity metals remain in the Li+depleted aqueous solution, or raffinate. The organic phase containing the extracted Li+complexes is optionally scrubbed to remove the remaining impurities. The optionally scrubbed organic phase is stripped, typically with an acid, to remove the Li+in a highly concentrated strip liquor. Finally, the Li+stripped organic phase is regenerated and recycled to the extraction stage.

[0260] The SX method may employ one or more of the following for Li+extraction: ^ Chelating extractants, such as without limitation a crown ether or an aza crown ether, or derivatives thereof. Examples of Li+-selective crown ethers include, without limitation: 12-crown-4, 13-crown-4, 14-crown-4, 15-crown-4, benzo-12-crown-4, benzo-14-crown-4, and dibenzo-14-crown-4. ^ Neutral extractants, such as without limitation a ketone, a f-diketone, a phosphate, or a phosphine oxide. Examples of neutral extractants include, without limitation: methyl isobutyl ketone (MIBK), 2,6-dimethyl-4-heptanone (DIBK), acetophenone (AP), 2-thenoyltrifluoroacetone (TTA), 1-phenyldecane-1,3-dione (LIX 54), 1,3-Diphenyl-1,3- propanedione (HDBM), benzoyltrifluoroacetone (BFA), 1-phenyl-3-methyl-4-benzoyl-5- pyrazolone (HPMBP), benzoyl-1,1,1-trifluoroacetone (HBTA), tri-n-butyl phosphate (TBP), triphenylphosphine oxide (TPPO), tri-n-octyl phosphine oxide (TOPO), and trialkyl phosphine oxide (Cyanex 923). ^ Ionizable extractants, such as compounds having any variety of ionizable functional groups, including without limitation carboxylic acid, phosphoric acid, or amine. Examples of ionizable extractants include, without limitation: organophosphorus acids such as di-(2-ethylhexyl)phosphoric acid (D2EHPA), 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (PC88A), mono-2-ethylhexyl-phosphoric acid (MEHPA), and bis-2,4,4-trimethyl pentyl phosphinic acid (Cyanex 272).^ Ionic liquids (ILs) – ILs are organic compounds comprised of ions with low melting points. They have many advantageous solvent properties, including high thermal stability, selectivity, and separation efficiency, but marginal volatility. Examples of ILs include, without limitation: a 1-alkyl-3-methylimidazolium-based ILs, such as 1-butyl-3- methylimidazolium hexafluorophosphate ([C4mim][PF6]), a 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ([C4mim][Tf2N]), or 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim][Tf2N]); tetrabutylammonium bis(2- ethylhexyl)phosphinate ([N4444][BEHP]); tetrabutylammonium bis(2-ethylhexyl)- phosphate ([N4444][DEHP]); tetraoctylammonium bis(2-ethylhexyl)-phosphate ([N8888][DEHP]); tetrabutylammonium mono-2-ethylhexyl(2-ethylhexyl)phosphate ([N4444][EHPMEH]); tetrabutylammonium 2-ethylhexyl hydrogen-2- ethylhexylphosphonate ([N4444][EHEHP]); tetrabutylammonium diisooctylphosphinate ([N4444][DICP]); tetrabutylphosphonium bis(2,4,4-trimethylpentyl) phosphinate ([P4444][BTMPP]); trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide ([P66614][Tf2N]); N-trimethyl-N-butylammonium bis(trifluoromethanesulfonyl)imide ([N1114][Tf2N]); 1-butyl-pyridinium bis((trifluoromethyl)sulfonyl)imide ([BPy][TF2N]); 1-butyl-1-methylpiperidinium bis((trifluoromethyl)sulfonyl)imide ([PP14][TF2N]); and 1-butyl-1-methylpyrrolidinium bis((trifluoromethyl)sulfonyl)imide ([P14][TF2N]).

[0261] The SX method may employ a multi-component system including an extractant, a co-extractant, a diluent, or a combination thereof. Examples of extractants include chelating, neutral, and / or ionizable extractants as described herein. The co-extractant may be one or more extractants described herein and / or an inorganic compound, such as without limitation FeCl3. Non-limiting examples of diluents include aliphatic solvents such as kerosene; aromatic solvents such as xylene; and ionic liquids. Non-limiting examples of the multi-component systems include HBTA - TOPO, TTA - TOPO in kerosene, TTA - 1,10-phenanthroline in chlorobenzene, TTA - TOPO in m-xylene / MIBK / n- hexane / benzene / chloroform, N,N-bis(2-ethylhexyl)-3-oxobutanamide (NB2EHOTA) - tri-n- butyl phosphate (TBP) - FeCl3, dioctyl phthalate (DOP) / acetyl tributyl citrate(ATBC) / tri-n-butyl citrate(TBC) -TBP - FeCl3, TBP / MIBK - FeCl3- kerosene, TBP - FeCl3- kerosene, TBP - MIBK - FeCl3, and LIX 54 - Cyanex 923.

[0262] FIG. 18 shows an exemplary embodiment of a use of the membrane electrolysis cell in a lithium production process where solvent extraction is used to selectivelyremove Li from a Li source comprising a lithium-containing solution. The solvent extraction step produces a lithium loaded solvent that may optionally be subjected to a scrubbing step to remove additional impurities. The lithium loaded solvent is then subjected to a stripping solution to produce a concentrated lithium-containing salt solution (e.g. LiCI or Li2SO4) and to regenerate the solvent. The concentrated lithium-containing salt solution is fed to the membrane electrolysis cell to simultaneously produce LiOH and acid (e.g. HCI or H2SO4). The acid produced from the membrane electrolysis cell may be used as stripping solution to remove the Li (e.g. as LiCI or Li2SO4) from the solvent, thus regenerating the solvent in the SX steps. Further, a portion of the LiOH produced from the membrane electrolysis cell may optionally be delivered to a step of precipitating at least one of calcium and magnesium from the lithium-containing solution before the SX steps. The exemplary steps in the process are as follows: Step 1: Lithium containing solution is processed with solvent to extract Li from the lithium-containing solution forming a Li loaded solvent. Step 2: The optionally scrubbed Li loaded solvent is stripped using stripping solution (e.g. acid) to produce a concentrated lithium salt-containing solution and to regenerate the solvent. Step 3: The concentrated lithium salt-containing solution is processed through the electrochemical cell to produce lithium hydroxide and acid. Step 4: The lithium hydroxide is sold to market or otherwise removed from the process while the acid is delivered to Step 2 to be used as the stripping solution.

[0263] It should be understood that in all of the foregoing embodiments depicting the use of the membrane electrolysis cells, together with the GDEs as described herein, in recovery processes for lithium, that the role of GDEs essentially remain the same between the various applications: to produce OH- ions from a humidified oxygen / air gas stream. Regardless of the salt used as the feed brine (LiCl, Li2SO4, Li3PO4, LiNO3, LiI, NaCl, Na2SO4, Na3PO4, NaNO3, NaI, KCl, K2SO4, K3PO4, KNO3, or KI), the cathode catalyst on the GDE always plays the same role.EXAMPLES Example 1

[0264] A GDE according to the present disclosure was prepared using AvcarbTMMGL370 carbon paper with teflonization as the GDL without a MPL. A catalyst ink was prepared by mixing 60% Platinum on Vulcan XC-72, FumionTMFAA-3 ionomer, and UltraflonTMMP-25 PTFE powder. The catalyst ink was applied to the carbon paper at a total catalyst loading of 1.5 mg / cm2. Example 2

[0265] A GDE according to the present disclosure was prepared using AvcarbTMMGL370 carbon paper with teflonization as the GDL without a MPL. A catalyst ink was prepared by mixing Pt Black, FumionTMFAA-3 ionomer, and UltraflonTMMP-25 PTFE powder. The catalyst ink was applied to the carbon paper at a total catalyst loading of 2 mg / cm2. Example 3

[0266] A GDE according to the present disclosure was prepared using TorayTMTGP-H-120 carbon paper with teflonization as the GDL without a MPL. A catalyst ink was prepared by mixing 60% Platinum on Vulcan XC-72, FumionTMFAA-3 ionomer, and UltraflonTMMP-25 PTFE powder. The catalyst ink was applied to the carbon paper at a total catalyst loading of 1.5 mg / cm2. Example 4

[0267] A GDE according to the present disclosure was prepared using Zoltek™ Panex PW03 carbon cloth with teflonization as the GDL without a MPL. A catalyst ink was prepared by mixing 80% Platinum on Vulcan XC-72, FumionTMFAA-3 ionomer, and UltraflonTMMP-25 PTFE powder. The catalyst ink was applied to the carbon cloth at a total catalyst loading of 2 mg / cm2. Example 5

[0268] A GDE according to the present disclosure was prepared using AvcarbTMMGL370 carbon paper with teflonization as the GDL without a MPL. A catalyst ink wasprepared by mixing 40% Platinum on Vulcan XC-72, FumionTMFAA-3 ionomer, and UltraflonTMMP-25 PTFE powder. The catalyst ink was applied to the carbon at a total catalyst loading of 0.4 mg / cm2. Example 6

[0269] A GDE according to the present disclosure was prepared using AvcarbTMMGL190 carbon paper with teflonization as the GDL without a MPL. A catalyst ink was prepared by mixing 40% Platinum on Vulcan XC-72, FumionTMFAA-3 ionomer, and UltraflonTMMP-25 PTFE powder. The catalyst ink was applied to the carbon paper at a total catalyst loading of 0.5 mg / cm2. Example 7

[0270] A GDE according to the present disclosure was prepared using SigracetTM25BA carbon paper with teflonization as the GDL without a MPL. A catalyst ink was prepared by mixing 40% Platinum on Vulcan XC-72 and IonomrTMAP1. The catalyst ink was applied to the carbon paper at a total catalyst loading of 0.5 mg / cm2. Example 8

[0271] A GDE according to the present disclosure was prepared using SigracetTM25BA carbon paper with teflonization as the GDL without a MPL. A catalyst ink was prepared by mixing 20% Platinum on Vulcan XC-72 and IonomrTMAP1. The catalyst ink was applied to the carbon paper at a total catalyst loading of 0.5 mg / cm2. Example 9

[0272] A GDE according to the present disclosure was prepared using AvcarbTMMGL370 carbon paper with teflonization as the GDL without a MPL. A catalyst ink was prepared by mixing 60% Platinum on Vulcan XC-72, FumionTMFAA-3 ionomer, and UltraflonTMMP-25 PTFE powder. The catalyst ink was applied to the carbon paper at a total catalyst loading of 2.5 mg / cm2. Example 10

[0273] A GDE according to the present disclosure was prepared using AvcarbTMMGL370 carbon paper as the GDL without a MPL. A catalyst ink was prepared by mixing40% Platinum on Vulcan XC-72, FumionTMFAA-3 ionomer, and UltraflonTMMP-25 PTFE powder. The catalyst ink was applied to the carbon paper at a total catalyst loading of 0.4 mg / cm2. Example 11

[0274] A GDE according to the present disclosure was prepared using FreudenbergTMH23C2 carbon paper as the GDL which includes a MPL. A 30 wt% Pt / C catalyst coating was applied to the GDL at a total catalyst loading of 1 mg / cm2. Example 12

[0275] A GDE according to the present disclosure was prepared using Zoltek™ Panex PW03 carbon cloth with teflonization as the GDL without a MPL. A catalyst ink was prepared by mixing 60% Platinum on Vulcan XC-72, FumionTMFAA-3 ionomer, and UltraflonTMMP-25 PTFE powder. The catalyst ink was applied to one side of the carbon cloth at a total catalyst loading of 1.5 mg / cm2and to the opposing side of the carbon cloth at a total catalyst loading of 0.5 mg / cm2. Example 13

[0276] A GDE according to the present disclosure was prepared using SigracetTM25BA carbon paper as the GDL without a MPL. A catalyst ink was prepared by mixing 60% Platinum on Vulcan XC-72 and FumionTMFAA-3 ionomer. The catalyst ink was applied to the carbon paper at a total catalyst loading of 0.4 mg / cm2. A Teflon dispersion was then applied on top of the catalyst layer at 50% loading. Example 14

[0277] A GDE according to the present disclosure was prepared using carbon cloth with teflonization as the GDL with an MPL. A catalyst ink was prepared by mixing 60% Silver on Vulcan XC-72 and IonomrTMAP3 ionomer. The catalyst ink was applied to the carbon cloth at a total catalyst loading of 3 mg / cm2. Example 15

[0278] A GDE according to the present disclosure was prepared using carbon cloth with teflonization as the GDL with an MPL. A catalyst ink was prepared by mixing 60%Platinum on Vulcan XC-72 and IonomrTMAP3 ionomer. The catalyst ink was applied to the carbon cloth at a total catalyst loading of 1 mg / cm2. Example 16

[0279] A GDE according to the present disclosure was prepared using carbon cloth with teflonization as the GDL with an MPL. A catalyst ink was prepared by mixing 60% Platinum on Vulcan XC-72 and IonomrTMAP3 ionomer. The catalyst ink was applied to the carbon cloth at a total catalyst loading of 2 mg / cm2. Example 17

[0280] A GDE according to the present disclosure was prepared using carbon cloth with teflonization as the GDL with an MPL. A catalyst ink was prepared by mixing 40% PtNi (3:1 ratio) on Vulcan XC-72 and IonomrTMAP3 ionomer. The catalyst ink was applied to the carbon cloth at a total catalyst loading of 1 mg / cm2. Example 18

[0281] A GDE according to the present disclosure was prepared using carbon cloth with teflonization as the GDL with an MPL. A catalyst ink was prepared by mixing 40% Ni on Vulcan XC-72 and IonomrTMAP3 ionomer. The catalyst ink was applied to the carbon cloth at a total catalyst loading of 2 mg / cm2. Example 19

[0282] A GDE according to the present disclosure was prepared using carbon cloth with teflonization as the GDL with an MPL. A catalyst ink was prepared by mixing 40% PtNi (1:1 ratio) on Vulcan XC-72 and IonomrTMAP3 ionomer. The catalyst ink was applied to the carbon cloth at a total catalyst loading of 1 mg / cm2. Example 20

[0283] The GDEs of Examples 1 to 19 were prepared and tested as an oxygen depolarized cathode in a multi-compartment membrane electrolysis cell as described herein for the production of a base product (e.g. LiOH) from a salt-containing solution (e.g. LiCl or Li2SO4). When a voltage was applied to the GDEs of Examples 1 to 19, a current was achieved.Example 21

[0284] Membrane coated GDEs according to the present disclosure were prepared by mixing an IonomrTManion exchange ionomer in a solvent to prepare a coating mixture. The coating mixture was applied to a GDE (e.g. a GDE comprising carbon cloth with teflonization as GDL with an MPL and having a Pt catalyst ink applied to the carbon cloth at a total catalyst loading of 1 mg / cm2) using a Doctor Blade method. The coating mixture was cured to form the membrane coated GDE. In particular, three membrane coated GDEs were prepared having membrane thicknesses of (i) 30 µm, (ii) 40 µm and (iii) 60 µm.

[0285] The above three membrane coated GDEs were tested as oxygen depolarized cathodes in a multi-compartment membrane electrolysis cell as described herein for the production of a base product (e.g. LiOH) from a salt-containing solution (e.g. LiCl or Li2SO4). When a voltage was applied to each of the three membrane coated GDEs, a current was achieved. It was observed that the thinner coated membrane showed better performance with respect to the voltage requirement for a specific current density. It was also observed that the membrane coated GDEs performed better than a control GDE hot-pressed to an anion exchange membrane. Example 22

[0286] MEAs with a textured membrane according to the present disclosure were prepared by (i) pressing an IonomrTManion exchange membrane (AEM) with a pattern template under heating and pressure for a period of time to form a textured membrane, and (ii) disposing the textured AEM onto a GDE forming the MEA with a textured membrane.

[0287] The above MEA with textured membrane was tested as an oxygen depolarized cathode in a multi-compartment membrane electrolysis cell as described herein for the production of a base product (e.g. LiOH) from a salt-containing solution (e.g. LiCl or Li2SO4). When a voltage was applied to the MEA, a current was achieved. It was observed that the MEA with a textured membrane showed better performance with respect to the voltage requirement for a specific current density than that of a MEA having a pristine membrane.Example 23

[0288] GDEs having an MPL according to the present disclosure were prepared by coating a GDL with a MPL formulation comprising equal parts Teflon and carbon powder by wt.% in a solvent. The MPL coatings underwent drying steps once coated onto the GDLs and before application of a catalyst layer. Several GDEs were prepared where the MPL formulations were mixed by different methods (e.g. stirring, sonication, or homogenization).

[0289] The above GDEs having an MPL were tested as oxygen depolarized cathodes in a multi-compartment membrane electrolysis cell as described herein for the production of a base product (e.g. LiOH) from a salt-containing solution (e.g. LiCl or Li2SO4). When a voltage was applied to the GDEs having an MPL, a current was achieved. It was observed that the method of mixing affected the viscosity of the MPL formulations. Also, the GDEs had differing voltage requirements for a specific current density depending on the mixing method. However, the GDEs having an MPL generally showed better performance than a commercially available GDE regardless of the mixing method.

[0290] Various non-limiting aspects of the invention may be summarized as follows:

[0291] Aspect 1. A gas diffusion electrode for use in a membrane electrolysis cell, the gas diffusion electrode comprising: a gas diffusion layer to diffuse a gas comprising oxygen; and a catalyst layer.

[0292] Aspect 2. The gas diffusion electrode of Aspect 1, wherein the catalyst layer is disposed on a surface of the gas diffusion layer.

[0293] Aspect 3. The gas diffusion electrode of Aspect 1, further comprising a microporous layer disposed on a surface of the gas diffusion layer, wherein the catalyst layer is disposed on a surface of the microporous layer opposite the gas diffusion layer.

[0294] Aspect 4. The gas diffusion electrode of Aspect 3, wherein the microporous layer comprises carbon black and a hydrophobic polymer.

[0295] Aspect 5. The gas diffusion electrode of Aspect 4, wherein the microporous layer comprises between 50 wt% and 95 wt% carbon black and 5 wt% and 50 wt% of hydrophobic polymer.

[0296] Aspect 6. The gas diffusion electrode of any one of Aspects 1 to 5, wherein the gas diffusion layer comprises carbon-fibre paper, carbon cloth, carbon felt, carbon foam, metal mesh, metal foam, or any combination thereof.

[0297] Aspect 7. The gas diffusion electrode of any one of Aspects 1 to 6, wherein the gas diffusion layer is modified with a hydrophobic polymer.

[0298] Aspect 8. The gas diffusion electrode of Aspect 7, wherein the hydrophobic polymer is polytetrafluoroethylene, polyvinylidene fluoride, fluorinated ethylene propylene, perfluoropolyether, polydimethylsiloxane, or any combination thereof.

[0299] Aspect 9. The gas diffusion electrode of Aspect 7 or 8, wherein the gas diffusion layer comprises between 0.01 wt% and 50 wt% hydrophobic polymer.

[0300] Aspect 10. The gas diffusion electrode of any one of Aspects 1 to 9, wherein the gas diffusion layer has a thickness of between 50 µm and 1000 µm.

[0301] Aspect 11. The gas diffusion electrode of any one of Aspects 1 to 10, wherein the gas diffusion layer has a porosity of between 50% and 95%.

[0302] Aspect 12. The gas diffusion electrode of any one of Aspects 1 to 11, wherein the catalyst layer comprises a catalyst and an ionomer.

[0303] Aspect 13. The gas diffusion electrode of Aspect 12, wherein the catalyst layer has an ionomer:catalyst ratio between 1:1 to 1:20.

[0304] Aspect 14. The gas diffusion electrode of Aspect 12 or 13, wherein the catalyst layer further comprises a binder.

[0305] Aspect 15. The gas diffusion electrode of Aspect 14, wherein the binder is PTFE.

[0306] Aspect 16. The gas diffusion electrode of Aspect 14 or 15, wherein the catalyst layer comprises between 0.01 wt% and 40 wt% of the binder.

[0307] Aspect 17. The gas diffusion electrode of any one of Aspects 12 to 16, wherein the catalyst is a metal, a non-metal, or a combination thereof.

[0308] Aspect 18. The gas diffusion electrode of Aspect 17, wherein the metal is a transition metal, a post-transition metal, a metalloid, or a combination thereof, or an alloy thereof.

[0309] Aspect 19. The gas diffusion electrode of Aspect 17, wherein the non-metal is carbon, a conductive polymer, or a combination thereof.

[0310] Aspect 20. The gas diffusion electrode of any one of Aspects 12 to 19, wherein the ionomer is an anion exchange ionomer.

[0311] Aspect 21. The gas diffusion electrode of Aspect 20, wherein the anion exchange ionomer is a FumionTMFAA-3, an IonomrTM, a Sustainion®, an Orion, a PentionTM, or a PiperION anion exchange ionomer.

[0312] Aspect 22. The gas diffusion electrode of any one of Aspects 12 to 21, wherein the catalyst layer comprises between 5 wt% and 45 wt% of the ionomer.

[0313] Aspect 23. The gas diffusion electrode of any one of Aspects 1 to 22, wherein the catalyst layer has a thickness of between 1 µm and 100 µm.

[0314] Aspect 24. The gas diffusion electrode of any one of Aspects 1 to 23, wherein the catalyst layer has a porosity of between 30% to 75%.

[0315] Aspect 25. The gas diffusion electrode of any one of Aspects 1 to 24, wherein the gas diffusion electrode is any one of GDE Embodiments 1 to 896 or 1a-896a as described herein.

[0316] Aspect 26. The gas diffusion electrode of any one of Aspects 1 to 25, further comprising an embossed and / or debossed pattern on at least one surface.

[0317] Aspect 27. The gas diffusion electrode of any one of Aspects 1 to 25, further comprising an anion exchange membrane disposed on a surface of the catalyst layer, the anion exchange membrane being configured to exchange ions from the catalyst layer to an opposed surface of the anion exchange membrane.

[0318] Aspect 28. The gas diffusion electrode of Aspect 27, wherein the anion exchange membrane comprises a polymer having at least one positively charged cationic group bound to at least a portion of a polymeric backbone.

[0319] Aspect 29. The gas diffusion electrode of Aspect 28, wherein the polymer comprises polyalkylene, a polyfluorene, a poly(arylene ether), a polysulfone, a poly(arylene ether sulfone), a polyetherketone, a polyetherimide, a poly(ether oxadiazole), a poly(phenylene oxide), a poly(vinyl benzyl), a polyphenylene, a perfluoro, a polybenzimidazole, a polystyrene, or a polyphosphazene.

[0320] Aspect 30. The gas diffusion electrode of Aspect 28 or 29, wherein the positively charged cationic group is a primary, secondary, tertiary or quaternary ammonium, a heterocyclic cation, a guanidinium, a phosphonium, a sulfonium, or a metal cation.

[0321] Aspect 31. The gas diffusion electrode of any one of Aspects 27 to 30, wherein the anion exchange membrane is a FumasepTM, a NeoseptaTM, an OrionTM, a Xergy Xion PentionTM, a PiperIONTM, a RalexTM, a SustanionTM, or an IonomrTManion exchange membrane.

[0322] Aspect 32. The gas diffusion electrode of any one of Aspects 27 to 31, further comprising an embossed and / or debossed pattern on at least one surface.

[0323] Aspect 33. A membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in the anode compartment; a cathode comprising a gas diffusion electrode as defined in any one of Aspects 1 to 26 positioned to extend within the interior of the membrane electrolysis cell and positioned in the cathode compartment; a cation exchange membrane interposed between the anode compartment and the catalyst layer of the gas diffusion electrode, the cation exchange membrane being configured to exchange ions received from the anode to an opposed surface of the cation exchange membrane; an inlet through which the salt-containing solution is received into the anode compartment; a gas inlet through which a gas comprising O2is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product of the salt solution is removed from an interior of the membrane electrolysis cell.

[0324] Aspect 34. A membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up compartment interposed between the cathode compartment and the anode compartment; an anode positioned to extend within the interior of themembrane electrolysis cell and positioned in an anode compartment; a cathode comprising a gas diffusion electrode as defined in any one of Aspects 1 to 26 positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; an anion exchange membrane being disposed on the catalyst layer of the gas diffusion electrode and being configured to exchange ions received from the catalyst layer of the gas diffusion electrode to an opposed surface of the anion ion exchange membrane into the base build-up compartment; a cation exchange membrane interposed between the anode compartment and the base build up compartment, the cation exchange membrane being configured to exchange ions received from the anode to an opposed surface of the cation exchange membrane into the base build-up compartment; an inlet through which the salt-containing solution is received into the anode compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2 is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

[0325] Aspect 35. A membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up compartment and a salt depletion compartment interposed between the cathode compartment and the anode compartment, the base build-up compartment is interposed between the cathode compartment and the salt depletion compartment, and the salt depletion compartment is interposed between the base build-up compartment and the anode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a gas diffusion electrode as defined in any one of Aspects 1 to 26 positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a first anion exchange membrane being disposed on the catalyst layer of the gas diffusion electrode and being configured to exchange ions received from the catalyst layer of the gas diffusion electrode to an opposed surface of the first anion ion exchange membrane into the base build-up compartment; a cation exchange membrane interposed between the salt depletion compartment and the base build-up compartment, the cation exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the cation exchange membrane into the base build- up compartment; a second anion exchange membrane interposed between the salt depletion compartment and the anode compartment, the second anion exchange membrane beingconfigured to exchange ions received from the salt depletion compartment to an opposed surface of the second anion exchange membrane into the anode compartment; an inlet through which the salt-containing solution is received into the salt depletion compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2 is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

[0326] Aspect 36. A membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up compartment, a salt depletion compartment and an acid build-up compartment interposed between the cathode compartment and the anode compartment, the base build-up compartment is interposed between the cathode compartment and the salt depletion compartment, the salt depletion compartment is interposed between the base build-up compartment and the acid build-up compartment, and the acid build-up compartment is interposed between the salt depletion compartment and the anode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a gas diffusion electrode as defined in any one of Aspects 1 to 26 positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a first anion exchange membrane, the first anion exchange membrane being disposed on the catalyst layer of the gas diffusion electrode and being configured to exchange ions received from the catalyst layer of the gas diffusion electrode to an opposed surface of the first anion ion exchange membrane into the base build-up compartment; a first cation exchange membrane interposed between the salt depletion compartment and the base build-up compartment, the cation exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the cation exchange membrane into the base build-up compartment; a second anion exchange membrane interposed between the salt depletion compartment and the acid build-up compartment, the second anion exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the second anion exchange membrane into the acid build-up compartment; a second cation exchange membrane interposed between the acid build-up compartment and the anode compartment, the second cation exchange membrane being configured to exchange ions received from the anode compartment to an opposed surface of the second cation exchange membrane into the acid build-upcompartment; an inlet through which the salt-containing solution is received into the salt depletion compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

[0327] Aspect 37. A process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in Aspect 33, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the anode compartment; the positive salt ions migrate through the cation exchange membrane to the opposed surface of the cation exchange membrane into the cathode compartment; the gas comprising O2is reduced at the cathode to form OH-;the OH- ions combine with the positive salt ions to produce the base product; and the base product is removed from the cathode compartment.

[0328] Aspect 38. A process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in Aspect 34, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the anode compartment; the positive salt ions migrate through the cation exchange membrane to the opposed surface of the cation exchange membrane into the base build-up compartment; the gas comprising O2is reduced at the cathode to form OH-;the OH- ions migrate through the anion exchange membrane to the opposed surface of the anion exchange membrane into the base build up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the base build-up compartment.

[0329] Aspect 39. A process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in Aspect 35, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the salt depletion compartment; the positive salt ions migrate through the cation exchange membrane to theopposed surface of the cation exchange membrane into the base build-up compartment; the gas comprising O2 is reduced at the cathode to form OH-;the OH- ions migrate through the first anion exchange membrane to the opposed surface of the first anion exchange membrane into the base build-up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the base build-up compartment.

[0330] Aspect 40. A process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in Aspect 36, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the salt depletion compartment; the positive salt ions migrate through the first cation exchange membrane to the opposed surface of the cation exchange membrane into the base build-up compartment; the gas comprising O2is reduced at the cathode to form OH-;the OH- ions migrate through the first anion exchange membrane to the opposed surface of the first anion exchange membrane into the base build-up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the base build-up compartment.

[0331] Aspect 41. A gas diffusion electrode for use in a membrane electrolysis cell, the gas diffusion electrode comprising: a gas diffusion layer to diffuse a gas comprising oxygen; and a catalyst coated membrane comprising a catalyst layer disposed on a surface of a membrane.

[0332] Aspect 42. The gas diffusion electrode of Aspect 41, wherein the membrane is an anion exchange membrane.

[0333] Aspect 43. The gas diffusion electrode of Aspect 42, wherein the anion exchange membrane comprises a polymer having at least one positively charged cationic group bound to at least a portion of a polymeric backbone.

[0334] Aspect 44. The gas diffusion electrode of Aspect 43, wherein the polymer comprises polyalkylene, a polyfluorene, a poly(arylene ether), a polysulfone, a poly(arylene ether sulfone), a polyetherketone, a polyetherimide, a poly(ether oxadiazole), apoly(phenylene oxide), a poly(vinyl benzyl), a polyphenylene, a perfluoro, a polybenzimidazole, a polystyrene, or a polyphosphazene.

[0335] Aspect 45. The gas diffusion electrode of Aspect 43 or 44, wherein the positively charged cationic group is a primary, secondary, tertiary or quaternary ammonium, a heterocyclic cation, a guanidinium, a phosphonium, a sulfonium, or a metal cation.

[0336] Aspect 46. The gas diffusion electrode of any one of Aspects 42 to 45, wherein the anion exchange membrane is a FumasepTM, a NeoseptaTM, an OrionTM, a Xergy Xion PentionTM, a PiperIONTM, a RalexTM, a SustanionTM, or an IonomrTManion exchange membrane.

[0337] Aspect 47. The gas diffusion electrode of any one of Aspects 41 to 46, wherein the gas diffusion layer is in contact with the catalyst layer of the catalyst coated membrane.

[0338] Aspect 48. The gas diffusion electrode of any one of Aspects 41 to 46, further comprising a microporous layer disposed on a surface of the gas diffusion layer, wherein the microporous layer is in contact with the catalyst layer of the catalyst coated membrane.

[0339] Aspect 49. The gas diffusion electrode of Aspect 48, wherein the microporous layer comprises carbon black and a hydrophobic polymer.

[0340] Aspect 50. The gas diffusion electrode of Aspect 48 or 49, wherein the microporous layer comprises between 50 wt% and 95 wt% carbon black and 5 wt% and 50 wt% of hydrophobic polymer.

[0341] Aspect 51. The gas diffusion electrode of any one of Aspects 41 to 50, wherein the gas diffusion layer comprises carbon-fibre paper, carbon cloth, carbon felt, carbon foam, metal mesh, metal foam, or any combination thereof.

[0342] Aspect 52. The gas diffusion electrode of any one of Aspects 41 to 51, wherein the gas diffusion layer is modified with a hydrophobic polymer.

[0343] Aspect 53. The gas diffusion electrode of Aspect 52, wherein the hydrophobic polymer is polytetrafluoroethylene, polyvinylidene fluoride, fluorinated ethylene propylene, perfluoropolyether, polydimethylsiloxane, or any combination thereof.

[0344] Aspect 54. The gas diffusion electrode of Aspect 52 or 53, wherein the gas diffusion layer comprises between 0.01 wt% and 50 wt% hydrophobic polymer.

[0345] Aspect 55. The gas diffusion electrode of any one of Aspects 41 to 54, wherein the gas diffusion layer has a thickness of between 50 µm and 1000 µm.

[0346] Aspect 56. The gas diffusion electrode of any one of Aspects 41 to 55, wherein the gas diffusion layer has a porosity of between 50% and 95%.

[0347] Aspect 57. The gas diffusion electrode of any one of Aspects 41 to 56, wherein the catalyst layer comprises a catalyst and an ionomer.

[0348] Aspect 58. The gas diffusion electrode of Aspect 57, wherein the catalyst layer has an ionomer:catalyst ratio between 1:1 to 1:20.

[0349] Aspect 59. The gas diffusion electrode of Aspect 57 or 58, wherein the catalyst layer further comprises a binder.

[0350] Aspect 60. The gas diffusion electrode of Aspect 59, wherein the binder is PTFE.

[0351] Aspect 61. The gas diffusion electrode of Aspect 59 or 60, wherein the catalyst layer comprises between 0.01 wt% and 40 wt% of the binder.

[0352] Aspect 62. The gas diffusion electrode of any one of Aspects 57 to 61, wherein the catalyst is a metal, a non-metal, or a combination thereof.

[0353] Aspect 63. The gas diffusion electrode of Aspect 62, wherein the metal is a transition metal, a post-transition metal, a metalloid, or a combination thereof, or an alloy thereof.

[0354] Aspect 64. The gas diffusion electrode of Aspect 62, wherein the non-metal is carbon, a conductive polymer, or a combination thereof.

[0355] Aspect 65. The gas diffusion electrode of any one of Aspects 57 to 64, wherein the ionomer is an anion exchange ionomer.

[0356] Aspect 66. The gas diffusion electrode of Aspect 65, wherein the anion exchange ionomer is a FumionTMFAA-3, an IonomrTM, a Sustainion®, an Orion, a PentionTM, or a PiperION anion exchange ionomer.

[0357] Aspect 67. The gas diffusion electrode of any one of Aspects 57 to 66, wherein the catalyst layer comprises between 5 wt% and 45 wt% of the ionomer.

[0358] Aspect 68. The gas diffusion electrode of any one of Aspects 41 to 67, wherein the catalyst layer has a thickness of between 1 µm and 100 µm.

[0359] Aspect 69. The gas diffusion electrode of any one of Aspects 41 to 68, wherein the catalyst layer has a porosity of between 30% to 75%.

[0360] Aspect 70. The gas diffusion electrode of any one of Aspects 41 to 69, wherein the gas diffusion electrode is any one of GDE Embodiments 1 to 896 or 1a-896a as described herein.

[0361] Aspect 71. The gas diffusion electrode of any one of Aspects 41 to 70, further comprising an embossed and / or debossed pattern on at least one surface.

[0362] Aspect 72. A membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up compartment interposed between the cathode compartment and the anode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a gas diffusion electrode as defined in any one of Aspects 41 to 71 positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a cation exchange membrane interposed between the anode compartment and the base build-up compartment, the cation exchange membrane being configured to exchange ions received from the anode to an opposed surface of the cation exchange membrane into the base build-up compartment; an inlet through which the salt-containing solution is received into the anode compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2 is introduced into contact with the gas diffusion electrode; andat least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

[0363] Aspect 73. A membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up compartment and a salt depletion compartment interposed between the cathode compartment and the anode compartment, the base build-up compartment is interposed between the cathode compartment and the salt depletion compartment, and the salt depletion compartment is interposed between the base build-up compartment and the anode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a gas diffusion electrode as defined in any one of Aspects 41 to 71 positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a cation exchange membrane interposed between the salt depletion compartment and the base build-up compartment, the cation exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the cation exchange membrane into the base build-up compartment; an anion exchange membrane interposed between the salt depletion compartment and the anode compartment, the anion exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the anion exchange membrane into the anode compartment ;an inlet through which the salt-containing solution is received into the salt depletion compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2 is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

[0364] Aspect 74. A membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up compartment, a salt depletion compartment and an acid build-up compartment interposed between the cathode compartment and the anode compartment, the base build-up compartment is interposed between the cathode compartment and the salt depletion compartment, the salt depletion compartment is interposed between the base build-up compartment and the acid build-up compartment, and the acid build-up compartment is interposed between the salt depletion compartment and the anode compartment; an anode positioned to extend within the interior of the membraneelectrolysis cell and positioned in an anode compartment; a cathode comprising a gas diffusion electrode as defined in any one of Aspects 41 to 71 positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a first cation exchange membrane interposed between the salt depletion compartment and the base build-up compartment, the cation exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the cation exchange membrane into the base build-up compartment; an anion exchange membrane interposed between the salt depletion compartment and the acid build-up compartment, the anion exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the anion exchange membrane into the acid build-up compartment; a second cation exchange membrane interposed between the acid build-up compartment and the anode compartment, the second cation exchange membrane being configured to exchange ions received from the anode compartment to an opposed surface of the second cation exchange membrane into the acid build-up compartment; an inlet through which the salt-containing solution is received into the salt depletion compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2 is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

[0365] Aspect 75. A process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in Aspect 72, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the anode compartment; the positive salt ions migrate through the cation exchange membrane to the opposed surface of the cation exchange membrane into the base build-up compartment; the gas comprising O2 is reduced at the cathode to form OH-;the OH- ions migrate through the catalyst coated membrane into the base build-up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the base build-up compartment.

[0366] Aspect 76. A process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in Aspect 73, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, whereinin performing the process: the salt-containing solution is received into the salt depletion compartment; the positive salt ions migrate through the cation exchange membrane to the opposed surface of the cation exchange membrane into the base build-up compartment; the gas comprising O2 is reduced at the cathode to form OH-;the OH- ions migrate through the catalyst coated exchange membrane into the base build-up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the base build-up compartment.

[0367] Aspect 77. A process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in Aspect 74, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the salt depletion compartment; the positive salt ions migrate through the first cation exchange membrane to the opposed surface of the first cation exchange membrane into the base build-up compartment; the gas comprising O2 is reduced at the cathode to form OH-;the OH- ions migrate through the catalyst coated membrane into the base build-up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the base build-up compartment.

[0368] Aspect 78. A gas diffusion electrode for use in a membrane electrolysis cell, the gas diffusion electrode comprising: a gas diffusion layer to diffuse a gas comprising oxygen; and a catalyst layer disposed on the gas diffusion layer, wherein the catalyst layer has a thickness optimized to substantially or completely consume a liquid reactant diffusing across the catalyst layer before reaching the gas diffusion layer.

[0369] Aspect 79. The gas diffusion electrode of Aspect 78, wherein the gas diffusion layer comprises carbon-fibre paper, carbon cloth, carbon felt, carbon foam, metal mesh, metal foam, or any combination thereof.

[0370] Aspect 80. The gas diffusion electrode of Aspect 78 or 79, wherein the gas diffusion layer is modified with a hydrophobic polymer.

[0371] Aspect 81. The gas diffusion electrode of Aspect 80, wherein the hydrophobic polymer is polytetrafluoroethylene, polyvinylidene fluoride, fluorinated ethylene propylene, perfluoropolyether, polydimethylsiloxane, or any combination thereof.

[0372] Aspect 82. The gas diffusion electrode of Aspect 80 or 81, wherein the gas diffusion layer comprises between 0.01 wt% and 50 wt% hydrophobic polymer.

[0373] Aspect 83. The gas diffusion electrode of any one of Aspects 78 to 82, wherein the gas diffusion layer has a thickness of between 50 µm and 1000 µm.

[0374] Aspect 84. The gas diffusion electrode of any one of Aspects 78 to 83, wherein the gas diffusion layer has a porosity of between 50% and 95%.

[0375] Aspect 85. The gas diffusion electrode of any one of Aspects 78 to 84, wherein the catalyst layer comprises a catalyst and an ionomer.

[0376] Aspect 86. The gas diffusion electrode of Aspect 85, wherein the catalyst layer has an ionomer:catalyst ratio between 1:1 to 1:20.

[0377] Aspect 87. The gas diffusion electrode of Aspect 85 or 86, wherein the catalyst layer further comprises a binder.

[0378] Aspect 88. The gas diffusion electrode of Aspect 87, wherein the binder is PTFE.

[0379] Aspect 89. The gas diffusion electrode of Aspect 87 or 88, wherein the catalyst layer comprises between 0.01 wt% and 40 wt% of the binder.

[0380] Aspect 90. The gas diffusion electrode of any one of Aspects 85 to 89, wherein the catalyst is a metal, a non-metal, or a combination thereof.

[0381] Aspect 91. The gas diffusion electrode of Aspect 90, wherein the metal is a transition metal, a post-transition metal, a metalloid, or a combination thereof, or an alloy thereof.

[0382] Aspect 92. The gas diffusion electrode of Aspect 90, wherein the non-metal is carbon, a conductive polymer, or a combination thereof.

[0383] Aspect 93. The gas diffusion electrode of any one of Aspects 85 to 92, wherein the ionomer is an anion exchange ionomer.

[0384] Aspect 94. The gas diffusion electrode of Aspect 93, wherein the anion exchange ionomer is a FumionTMFAA-3, an IonomrTM, a Sustainion®, an Orion, a PentionTM, or a PiperION anion exchange ionomer.

[0385] Aspect 95. The gas diffusion electrode of any one of Aspects 85 to 94, wherein the catalyst layer comprises between 5 wt% and 45 wt% of the ionomer.

[0386] Aspect 96. The gas diffusion electrode of any one of Aspects 78 to 95, wherein the catalyst layer has a thickness of between 1 µm and 100 µm.

[0387] Aspect 97. The gas diffusion electrode of any one of Aspects 78 to 96, wherein the catalyst layer has a porosity of between 30% to 75%.

[0388] Aspect 98. The gas diffusion electrode of any one of Aspects 78 to 97, wherein the gas diffusion electrode is any one of GDE Embodiments 1 to 896 or 1a-896a as described herein.

[0389] Aspect 99. The gas diffusion electrode of any one of Aspects 78 to 98, further comprising an embossed and / or debossed pattern on at least one surface.

[0390] Aspect 100. A membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up together with the cathode compartment forming a single compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a gas diffusion electrode as defined in any one of Aspects 78 to 99 positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a cation exchange membrane interposed between the anode compartment and the base build-up compartment, the cation exchange membrane being configured to exchange ions received from the anode to an opposed surface of the cation exchange membrane into the base build-up compartment; an inlet through which the salt-containing solution is received into the anode compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

[0391] Aspect 101. A membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathodecompartment; a base build-up together with the cathode compartment forming a single compartment; a salt depletion compartment interposed between the cathode compartment and the anode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a gas diffusion electrode as defined in any one of Aspects 78 to 99 positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a cation exchange membrane interposed between the salt depletion compartment and the base build-up compartment, the cation exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the cation exchange membrane into the base build-up compartment; an anion exchange membrane interposed between the salt depletion compartment and the anode compartment, the anion exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the anion exchange membrane into the anode compartment; an inlet through which the salt-containing solution is received into the salt depletion compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

[0392] Aspect 102. A membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up together with the cathode compartment forming a single compartment; a salt depletion compartment and an acid build up compartment interposed between the cathode compartment and the anode compartment, the salt depletion compartment is interposed between the base build-up compartment and the acid build-up compartment, and the acid build-up compartment is interposed between the salt depletion compartment and the anode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a gas diffusion electrode as defined in any one of Aspects 78 to 99 positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a first cation exchange membrane interposed between the salt depletion compartment and the base build-up compartment, the cation exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the cation exchange membrane into the base build-up compartment; an anion exchange membrane interposed between the salt depletion compartment and the acidbuild-up compartment, the anion exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the anion exchange membrane into the acid build-up compartment; a second cation exchange membrane interposed between the acid build-up compartment and the anode compartment, the second cation exchange membrane being configured to exchange ions received from the anode compartment to an opposed surface of the second cation exchange membrane into the acid build-up compartment; an inlet through which the salt-containing solution is received into the salt depletion compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

[0393] Aspect 103. A process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in Aspect 100, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the anode compartment; the positive salt ions migrate through the cation exchange membrane to the opposed surface of the cation exchange membrane into the base build-up compartment; the gas comprising O2is reduced at the cathode to form OH-;the OH- ions migrate through the catalyst layer into the base build-up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the membrane electrolysis cell.

[0394] Aspect 104. A process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in Aspect 101, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the salt depletion compartment; the positive salt ions migrate through the cation exchange membrane to the opposed surface of the cation exchange membrane into the base build-up compartment; the gas comprising O2 is reduced at the cathode to form OH-;the OH- ions migrate through the catalyst layer into the base build-up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the membrane electrolysis cell.

[0395] Aspect 105. A process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in Aspect 102, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the salt depletion compartment; the positive salt ions migrate through the first cation exchange membrane to the opposed surface of the first cation exchange membrane into the base build-up compartment; the gas comprising O2 is reduced at the cathode to form OH-;the OH- ions migrate through the catalyst layer into the base build-up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the membrane electrolysis cell.

[0396] Aspect 106. A gas diffusion electrode for use in a membrane electrolysis cell, the gas diffusion electrode comprising: a first gas diffusion layer to diffuse a gas comprising oxygen; a catalyst layer disposed on a surface of the first gas diffusion layer; a second gas diffusion layer contacting a surface of the catalyst layer opposite the first gas diffusion layer; and an ionomer layer disposed on a surface of an anion exchange membrane, the ionomer layer is in contact with a surface of the second gas diffusion layer opposite the catalyst layer.

[0397] Aspect 107. The gas diffusion electrode of Aspect 106, further comprising a microporous layer disposed on a surface of the second gas diffusion layer, wherein the microporous layer is in contact with the surface of the catalyst layer opposite the first gas diffusion layer.

[0398] Aspect 108. A process for producing LiOH from a Li source, the process comprising the steps of: (a) contacting the Li source with a solvent to remove lithium from the Li source so as to obtain a lithium loaded solvent;(b) contacting the lithium loaded solvent with a stripping agent to regenerate the solvent and to produce a salt-containing solution comprising lithium ions and negative salt ions; (c) receiving, in a membrane electrolysis cell, the salt-containing solution and a gas comprising O2; and (d) delivering, from the membrane electrolysis cell, LiOH and / or acid.

[0399] Aspect 109. The process of Aspect 108, wherein the salt-containing solution comprises LiCl or Li2SO4.

[0400] Aspect 110. The process of Aspect 108, wherein the acid is HCl or H2SO4.

[0401] Aspect 111. The process of any one of Aspects 108 to 110, wherein the solvent comprises one or more of a chelating extractant, a neutral extractant, an ionizable extractant, and an ionic liquid.

[0402] Aspect 112. The process of any one of Aspects 108 to 110, wherein the solvent comprises a multi-component system including an extractant, a co-extractant, a diluent, or a combination thereof.

[0403] Aspect 113. The process of any one of Aspects 108 to 112, further comprising a step of purifying the lithium loaded solvent by exposure to a scrub solution prior to contacting the lithium loaded solvent with the stripping agent.

[0404] Aspect 114. The process of any one of Aspects 108 to 113, further comprising feeding a portion of the acid delivered in step (d) to step (b) for use as the stripping agent.

[0405] Aspect 115. The process of any one of Aspects 108 to 114, further comprising precipitating at least one of calcium and magnesium from the Li source.

[0406] Aspect 116. The process of Aspect 115, further comprising feeding a portion of the LiOH delivered in step (d) to the step of precipitating at least one of calcium and magnesium from the Li source.

[0407] Aspect 117. A membrane coated gas diffusion electrode for use in a membrane electrolysis cell, the membrane coated gas diffusion electrode comprising: a gas diffusion electrode comprising a gas diffusion layer to diffuse a gas comprising oxygen and a catalyst layer; and an anion exchange membrane coated on the gas diffusion electrode.

[0408] Aspect 118. A process for preparing a membrane coated gas diffusion electrode, the process comprising: mixing an ionomer in a solvent to prepare a coating mixture; applying the coating mixture to a gas diffusion electrode, and curing to form the membrane coated gas diffusion electrode.

[0409] Aspect 119. The process of Aspect 118, wherein the ionomer comprises a FumionTMionomer, an IonomrTMionomer, a Sustainion® ionomer, an Orion ionomer, a PentionTMionomer, or a PiperION ionomer.

[0410] Aspect 120. The process of Aspect 118 or 119, wherein the solvent comprises an alcohol.

[0411] Aspect 121, The process of any one of Aspects 118 to 120, wherein the ionomer is mixed in the solvent at a concentration of between 2 and 15 wt.%.

[0412] Aspect 122. The process of any one of Aspects 118 to 121, wherein the gas diffusion electrode comprises a gas diffusion layer to diffuse a gas comprising oxygen and a catalyst layer.

[0413] Aspect 123. The process of any one of Aspects 118 to 122, wherein the coating mixture has a thickness of between 20 µm and 100 µm.

[0414] Aspect 124. The process of any one of Aspects 118 to 123, wherein the curing is at a temperature of between 50oC and 140oC.

[0415] In the present disclosure, all terms referred to in singular form are meant to encompass plural forms of the same. Likewise, all terms referred to in plural form are meant to encompass singular forms of the same. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0416] As used herein, the term “about” refers to an approximately + / -10 % variation from a given value. It is to be understood that such a variation is always included in any given value provided herein, whether or not it is specifically referred to.

[0417] It should be understood that the compositions and methods are described in terms of "comprising," "containing," or "including" various components or steps, the compositions and methods can also "consist essentially of or "consist of the various components and steps. Moreover, the indefinite articles "a" or "an," as used in the claims, are defined herein to mean one or more than one of the element that it introduces.

[0418] For the sake of brevity, only certain ranges are explicitly disclosed herein. However, ranges from any lower limit may be combined with any upper limit to recite a range not explicitly recited, as well as, ranges from any lower limit may be combined with any other lower limit to recite a range not explicitly recited, in the same way, ranges from any upper limit may be combined with any other upper limit to recite a range not explicitly recited. Additionally, whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range are specifically disclosed. In particular, every range of values (of the form, "from about a to about b," or, equivalently, "from approximately a to b," or, equivalently, "from approximately a-b") disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values even if not explicitly recited. Thus, every point or individual value may serve as its own lower or upper limit combined with any other point or individual value or any other lower or upper limit, to recite a range not explicitly recited.

[0419] Therefore, the present disclosure is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the present disclosure may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Although individual embodiments are discussed, the disclosure covers all combinations of all those embodiments. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. It is therefore evident that the particular illustrative embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the present disclosure. If there is any conflict in the usages of a word or term in this specification and one or more patent(s) or other documents that may be referenced herein, the definitions that are consistent with this specification should be adopted.

[0420] Many obvious variations of the embodiments set out herein will suggest themselves to those skilled in the art in light of the present disclosure. Such obvious variations are within the full intended scope of the appended claims.

Claims

CLAIMS:

1. A gas diffusion electrode for use in a membrane electrolysis cell, the gas diffusion electrode comprising: a gas diffusion layer to diffuse a gas comprising oxygen; and a catalyst layer.

2. A membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in the anode compartment; a cathode comprising a gas diffusion electrode as defined in claim 1 positioned to extend within the interior of the membrane electrolysis cell and positioned in the cathode compartment; a cation exchange membrane interposed between the anode compartment and the catalyst layer of the gas diffusion electrode, the cation exchange membrane being configured to exchange ions received from the anode to an opposed surface of the cation exchange membrane; an inlet through which the salt-containing solution is received into the anode compartment; a gas inlet through which a gas comprising O2is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product of the salt solution is removed from an interior of the membrane electrolysis cell.

3. A membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment;a base build-up compartment interposed between the cathode compartment and the anode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a gas diffusion electrode as defined in claim 1 positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; an anion exchange membrane being disposed on the catalyst layer of the gas diffusion electrode and being configured to exchange ions received from the catalyst layer of the gas diffusion electrode to an opposed surface of the anion ion exchange membrane into the base build-up compartment; a cation exchange membrane interposed between the anode compartment and the base build up compartment, the cation exchange membrane being configured to exchange ions received from the anode to an opposed surface of the cation exchange membrane into the base build-up compartment; an inlet through which the salt-containing solution is received into the anode compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2 is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

4. A membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up compartment and a salt depletion compartment interposed between the cathode compartment and the anode compartment, the base build-up compartment is interposed between the cathode compartment and the salt depletion compartment, and the salt depletion compartment is interposed between the base build-up compartment and the anode compartment;an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a gas diffusion electrode as defined in claim 1 positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a first anion exchange membrane being disposed on the catalyst layer of the gas diffusion electrode and being configured to exchange ions received from the catalyst layer of the gas diffusion electrode to an opposed surface of the first anion ion exchange membrane into the base build-up compartment; a cation exchange membrane interposed between the salt depletion compartment and the base build-up compartment, the cation exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the cation exchange membrane into the base build-up compartment; a second anion exchange membrane interposed between the salt depletion compartment and the anode compartment, the second anion exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the second anion exchange membrane into the anode compartment; an inlet through which the salt-containing solution is received into the salt depletion compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2 is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

5. A membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up compartment, a salt depletion compartment and an acid build-up compartment interposed between the cathode compartment and the anode compartment, the base build-up compartment is interposed between the cathode compartment and the saltdepletion compartment, the salt depletion compartment is interposed between the base build- up compartment and the acid build-up compartment, and the acid build-up compartment is interposed between the salt depletion compartment and the anode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a gas diffusion electrode as defined in claim 1 positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a first anion exchange membrane, the first anion exchange membrane being disposed on the catalyst layer of the gas diffusion electrode and being configured to exchange ions received from the catalyst layer of the gas diffusion electrode to an opposed surface of the first anion ion exchange membrane into the base build-up compartment; a first cation exchange membrane interposed between the salt depletion compartment and the base build-up compartment, the cation exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the cation exchange membrane into the base build-up compartment; a second anion exchange membrane interposed between the salt depletion compartment and the acid build-up compartment, the second anion exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the second anion exchange membrane into the acid build-up compartment; a second cation exchange membrane interposed between the acid build-up compartment and the anode compartment, the second cation exchange membrane being configured to exchange ions received from the anode compartment to an opposed surface of the second cation exchange membrane into the acid build-up compartment; an inlet through which the salt-containing solution is received into the salt depletion compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2 is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

6. A process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in claim 2, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the anode compartment; the positive salt ions migrate through the cation exchange membrane to the opposed surface of the cation exchange membrane into the cathode compartment; the gas comprising O2is reduced at the cathode to form OH-; the OH- ions combine with the positive salt ions to produce the base product; and the base product is removed from the cathode compartment.

7. A process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in claim 3, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the anode compartment; the positive salt ions migrate through the cation exchange membrane to the opposed surface of the cation exchange membrane into the base build-up compartment; the gas comprising O2is reduced at the cathode to form OH-; the OH- ions migrate through the anion exchange membrane to the opposed surface of the anion exchange membrane into the base build up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the base build-up compartment.

8. A process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in claim 4, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the salt depletion compartment; the positive salt ions migrate through the cation exchange membrane to the opposed surface of the cation exchange membrane into the base build-up compartment; the gas comprising O2 is reduced at the cathode to form OH-; the OH- ions migrate through the first anion exchange membrane to the opposed surface of the first anion exchange membrane into the base build-up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the base build-up compartment.

9. A process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in claim 5, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the salt depletion compartment; the positive salt ions migrate through the first cation exchange membrane to the opposed surface of the cation exchange membrane into the base build-up compartment; the gas comprising O2 is reduced at the cathode to form OH-;the OH- ions migrate through the first anion exchange membrane to the opposed surface of the first anion exchange membrane into the base build-up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the base build-up compartment.

10. A gas diffusion electrode for use in a membrane electrolysis cell, the gas diffusion electrode comprising: a gas diffusion layer to diffuse a gas comprising oxygen; and a catalyst coated membrane comprising a catalyst layer disposed on a surface of a membrane.

11. A membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up compartment interposed between the cathode compartment and the anode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a gas diffusion electrode as defined in claim 10 positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a cation exchange membrane interposed between the anode compartment and the base build-up compartment, the cation exchange membrane being configured to exchange ions received from the anode to an opposed surface of the cation exchange membrane into the base build-up compartment; an inlet through which the salt-containing solution is received into the anode compartment;a gas inlet positioned in the cathode compartment through which the gas comprising O2 is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

12. A membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up compartment and a salt depletion compartment interposed between the cathode compartment and the anode compartment, the base build-up compartment is interposed between the cathode compartment and the salt depletion compartment, and the salt depletion compartment is interposed between the base build-up compartment and the anode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a gas diffusion electrode as defined in claim 10 positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a cation exchange membrane interposed between the salt depletion compartment and the base build-up compartment, the cation exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the cation exchange membrane into the base build-up compartment; an anion exchange membrane interposed between the salt depletion compartment and the anode compartment, the anion exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the anion exchange membrane into the anode compartment; an inlet through which the salt-containing solution is received into the salt depletion compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2 is introduced into contact with the gas diffusion electrode; andat least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

13. A membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up compartment, a salt depletion compartment and an acid build-up compartment interposed between the cathode compartment and the anode compartment, the base build-up compartment is interposed between the cathode compartment and the salt depletion compartment, the salt depletion compartment is interposed between the base build- up compartment and the acid build-up compartment, and the acid build-up compartment is interposed between the salt depletion compartment and the anode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a gas diffusion electrode as defined in claim 10 positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a first cation exchange membrane interposed between the salt depletion compartment and the base build-up compartment, the cation exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the cation exchange membrane into the base build-up compartment; an anion exchange membrane interposed between the salt depletion compartment and the acid build-up compartment, the anion exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the anion exchange membrane into the acid build-up compartment; a second cation exchange membrane interposed between the acid build-up compartment and the anode compartment, the second cation exchange membrane being configured to exchange ions received from the anode compartment to an opposed surface of the second cation exchange membrane into the acid build-up compartment;an inlet through which the salt-containing solution is received into the salt depletion compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2 is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

14. A process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in claim 11, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the anode compartment; the positive salt ions migrate through the cation exchange membrane to the opposed surface of the cation exchange membrane into the base build-up compartment; the gas comprising O2 is reduced at the cathode to form OH-; the OH- ions migrate through the catalyst coated membrane into the base build-up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the base build-up compartment.

15. A process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in claim 12, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the salt depletion compartment;the positive salt ions migrate through the cation exchange membrane to the opposed surface of the cation exchange membrane into the base build-up compartment; the gas comprising O2 is reduced at the cathode to form OH-; the OH- ions migrate through the catalyst coated exchange membrane into the base build-up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the base build-up compartment.

16. A process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in claim 13, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the salt depletion compartment; the positive salt ions migrate through the first cation exchange membrane to the opposed surface of the first cation exchange membrane into the base build-up compartment; the gas comprising O2 is reduced at the cathode to form OH-; the OH- ions migrate through the catalyst coated membrane into the base build-up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the base build-up compartment.

17. A gas diffusion electrode for use in a membrane electrolysis cell, the gas diffusion electrode comprising: a gas diffusion layer to diffuse a gas comprising oxygen; anda catalyst layer disposed on the gas diffusion layer, wherein the catalyst layer has a thickness optimized to substantially or completely consume a liquid reactant diffusing across the catalyst layer before reaching the gas diffusion layer.

18. A membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment; a base build-up together with the cathode compartment forming a single compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a gas diffusion electrode as defined in claim 17 positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a cation exchange membrane interposed between the anode compartment and the base build-up compartment, the cation exchange membrane being configured to exchange ions received from the anode to an opposed surface of the cation exchange membrane into the base build-up compartment; an inlet through which the salt-containing solution is received into the anode compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

19. A membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment;a cathode compartment; a base build-up together with the cathode compartment forming a single compartment; a salt depletion compartment interposed between the cathode compartment and the anode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a gas diffusion electrode as defined in claim 17 positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a cation exchange membrane interposed between the salt depletion compartment and the base build-up compartment, the cation exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the cation exchange membrane into the base build-up compartment; an anion exchange membrane interposed between the salt depletion compartment and the anode compartment, the anion exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the anion exchange membrane into the anode compartment; an inlet through which the salt-containing solution is received into the salt depletion compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2 is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

20. A membrane electrolysis cell for processing a salt-containing solution, the membrane electrolysis cell comprising: an anode compartment; a cathode compartment;a base build-up together with the cathode compartment forming a single compartment; a salt depletion compartment and an acid build up compartment interposed between the cathode compartment and the anode compartment, the salt depletion compartment is interposed between the base build-up compartment and the acid build-up compartment, and the acid build-up compartment is interposed between the salt depletion compartment and the anode compartment; an anode positioned to extend within the interior of the membrane electrolysis cell and positioned in an anode compartment; a cathode comprising a gas diffusion electrode as defined in claim 17 positioned to extend within the interior of the membrane electrolysis cell and positioned in a cathode compartment; a first cation exchange membrane interposed between the salt depletion compartment and the base build-up compartment, the cation exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the cation exchange membrane into the base build-up compartment; an anion exchange membrane interposed between the salt depletion compartment and the acid build-up compartment, the anion exchange membrane being configured to exchange ions received from the salt depletion compartment to an opposed surface of the anion exchange membrane into the acid build-up compartment; a second cation exchange membrane interposed between the acid build-up compartment and the anode compartment, the second cation exchange membrane being configured to exchange ions received from the anode compartment to an opposed surface of the second cation exchange membrane into the acid build-up compartment; an inlet through which the salt-containing solution is received into the salt depletion compartment; a gas inlet positioned in the cathode compartment through which the gas comprising O2is introduced into contact with the gas diffusion electrode; and at least one outlet through which a product is removed from an interior of the membrane electrolysis cell.

21. A process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in claim 18, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the anode compartment; the positive salt ions migrate through the cation exchange membrane to the opposed surface of the cation exchange membrane into the base build-up compartment; the gas comprising O2 is reduced at the cathode to form OH-; the OH- ions migrate through the catalyst layer into the base build-up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the membrane electrolysis cell.

22. A process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in claim 19, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the salt depletion compartment; the positive salt ions migrate through the cation exchange membrane to the opposed surface of the cation exchange membrane into the base build-up compartment; the gas comprising O2 is reduced at the cathode to form OH-; the OH- ions migrate through the catalyst layer into the base build-up compartment;the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the membrane electrolysis cell.

23. A process for producing a base product, the process comprising the steps of: receiving, in a membrane electrolysis cell as defined in claim 20, a salt-containing solution comprising positive salt ions and negative salt ions, and a gas comprising O2; and delivering the base product from the membrane electrolysis cell, wherein in performing the process: the salt-containing solution is received into the salt depletion compartment; the positive salt ions migrate through the first cation exchange membrane to the opposed surface of the first cation exchange membrane into the base build-up compartment; the gas comprising O2is reduced at the cathode to form OH-; the OH- ions migrate through the catalyst layer into the base build-up compartment; the OH- ions combine with the positive salt ions in the base build-up compartment to produce the base product; and the base product is removed from the membrane electrolysis cell.

24. A gas diffusion electrode for use in a membrane electrolysis cell, the gas diffusion electrode comprising: a first gas diffusion layer to diffuse a gas comprising oxygen; a catalyst layer disposed on a surface of the first gas diffusion layer; a second gas diffusion layer contacting a surface of the catalyst layer opposite the first gas diffusion layer; and an ionomer layer disposed on a surface of an anion exchange membrane, the ionomer layer is in contact with a surface of the second gas diffusion layer opposite the catalyst layer.

25. A process for producing LiOH from a Li source, the process comprising the steps of: (a) contacting the Li source with a solvent to remove lithium from the Li source so as to obtain a lithium loaded solvent; (b) contacting the lithium loaded solvent with a stripping agent to regenerate the solvent and to produce a salt-containing solution comprising lithium ions and negative salt ions; (c) receiving, in a membrane electrolysis cell, the salt-containing solution and a gas comprising O2; and (d) delivering, from the membrane electrolysis cell, LiOH and / or acid.

26. A process for preparing a membrane coated gas diffusion electrode, the process comprising: mixing an ionomer in a solvent to prepare a coating mixture; applying the coating mixture to a gas diffusion electrode, and curing to form the membrane coated gas diffusion electrode.

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