Processes and systems for producing an alkali metal compound using an electrochemical cell

Abstract

There are provided processes and systems for producing an alkali metal compound. In particular, there are provided processes and systems for producing an alkali compound that involve the combined use of electrochemical cells and generators (e.g. steam or electrical power).

Description

PROCESSES AND SYSTEMS FOR PRODUCING AN ALKALI METAL COMPOUND USING AN ELECTROCHEMICAL CELLCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to and benefit from United States Patent Application Serial No. 63 / 572,706 filed on April 1 , 2024, which is hereby incorporated by reference in its entirety.TECHNICAL FIELD

[0002] The present disclosure generally relates to processes and systems for producing alkali metal compounds using an electrochemical cell, and in particular a multi-compartment membrane electrolysis cell.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 alkali metals that can be used in batteries and / or other machinery, including for example high-quality battery grade lithium (lithium hydroxide and lithium carbonate).

[0004] Current processes for lithium mining can be inefficient and have aspects that are harmful to the environment. One of the processes for mining lithium is from lithium brines that are high in lithium chloride content, as well as other metals and minerals.

[0005] 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. Introductionof soda ash, Na2CC>3, to convert the dissolved lithium salts to lithium carbonate, IJ2CO3, is the last major step to produce technical and high purity lithium carbonate.

[0006] These existing processes of lithium processing are not efficient or environmentally friendly in their handling of water. The underground water that is brought to surface is evaporated off into the atmosphere, which is detrimental in respect of this valuable natural resource. Moreover, underground voids that are created from removing the brine may be replaced by leaching of underground water from aquifers that are used for drinking water, thereby reducing the supply of fresh drinking water.

[0007] Other aspects of existing lithium processing procedures are likewise inefficient and wasteful in their handling of valuable resources, such as by-products from electrochemical cells used in processing salt solutions to generate high-quality battery grade lithium.

[0008] There is an existing need for improved processes and system for producing alkali metal compounds, such as high-quality battery grade lithium, that are more environmentally friendly and more efficient in their use of valuable resources.SUMMARY

[0009] The present disclosure provides processes for improved methods and systems for producing an alkali metal compound.

[0010] The processes and systems herein for producing an alkali metal compound advantageously reduce or eliminate the wasteful evaporation of water into the atmosphere and provide electrical power from previous waste streams.

[0011] In an embodiment, the present disclosure relates to a process for producing an alkali metal compound comprising: receiving a salt solution in a solar-powered steam generator to produce steam and a salt solution concentrate; delivering the salt solution concentrate to an electrochemical cell; generating electrical power by directing at least a portion of the steam to a turbine coupled to a generator; and powering the electrochemical cell with the electrical power to produce a product solution comprising the alkali metal compound from the salt solution concentrate.

[0012] In an embodiment, the process further comprises producing a condensate from the step of generating electrical power. In an embodiment, the condensate is used for water consumption in the electrochemical cell, recycled to an underground reservoir, or a combination thereof.

[0013] In an embodiment of the processes herein, the solar-powered steam generator is powered by a solar parabolic trough, a solar dish, a solar power tower, a linear Fresnel reflector, or any combination thereof.

[0014] In an embodiment of the processes herein, the salt solution is an aqueous brine obtained from an underground deposit or reservoir. In an embodiment, the salt solution comprises LiCI, Li2SO4, Li3PO4, LiNCh, Lil, LiBr, NaCI, Na2SO4, Na3PO4, NaNCh, Nal, NBr, KCI, K2SO4, K3PO4, KNO3, KI, KBr, or any combination thereof.

[0015] In an embodiment of the processes herein, the salt solution concentrate is pre-treated before being delivered to the electrochemical cell. In an embodiment, the salt solution concentrate is pre-treated to remove divalent cations. In an embodiment, the salt solution concentrate is pre-treated to remove boron.

[0016] In an embodiment of the processes herein, the alkali metal compound within the product solution comprises LiOH, NaOH, KOH, or any combination thereof.

[0017] In an embodiment, the processes herein further comprise a step of crystallizing the alkali metal compound from the product solution.

[0018] In an embodiment of the processes herein, the electrochemical cell is any one or more of the electrochemical cells as described herein.

[0019] In an embodiment, the present disclosure relates to a system for producing an alkali metal compound, the system comprising a solar-powered steam generator; an electrochemical cell fluidly coupled to the solar-powered steam generator; a turbine fluidly coupled to the solar-powered steam generator; and a generator coupled to the turbine to generate electrical power.

[0020] In an embodiment of the system herein, the solar-powered steam generator is configured to receive a salt solution. In an embodiment, the salt solution is an aqueous brine obtained from an underground deposit or reservoir. In an embodiment, the salt solutioncomprises LiCI, Li2SO4, Li3PO4, LiNO3, Lil, LiBr, NaCI, Na2SO4, Na3PO4, NaNO3, Nal, NBr, KCI, K2SO4, K3PO4, KNO3, KI, KBr, or any combination thereof.

[0021] In an embodiment of the system herein, the electrochemical cell is configured to receive a salt solution concentrate from the solar-powered steam generator.

[0022] In an embodiment, the system herein further comprises one or more pre-treatment components for pre-treating the salt solution concentrate prior to the salt solution concentrate being received by the electrochemical cell. In an embodiment, the one or more pre-treatment components are configured to remove divalent cations, boron, or a combination thereof from the salt solution concentrate.

[0023] In an embodiment of the system herein, the electrochemical cell is the electrochemical cell as described herein.

[0024] In an embodiment, the system herein further comprises a cooling device for converting at least a portion of the steam formed by the solar-powered steam generator into a condensate.

[0025] In an embodiment, the system herein is configured to deliver the condensate to the electrochemical cell, an underground reservoir, or a combination thereof.

[0026] In an embodiment of the system herein, the solar-powered steam generator comprises and / or is powered by a solar parabolic trough, a solar dish, a solar power tower, a linear Fresnel reflector, or any combination thereof.

[0027] In an embodiment of the system herein, the electrochemical cell produces a product solution comprising an alkali metal compound. In an embodiment, the alkali metal compound is LiOH, NaOH, KOH, or any combination thereof.

[0028] In an embodiment, the system herein further comprises a crystallization unit for crystallizing the alkali metal compound from the product solution.

[0029] In an embodiment, the present disclosure relates to a process for producing an alkali metal compound comprising: receiving a salt solution in an electrochemical cell comprising a cathode and an anode; applying an electrical potential between the cathode and anode; producing hydrogen gas at the cathode; producing from the electrochemical cella product solution comprising the alkali metal compound; and delivering the hydrogen gas to a hydrogen fuel cell to generate electrical power.

[0030] In an embodiment of the process herein, the electrical power is used to power the electrochemical cell.

[0031] In an embodiment, the process herein further comprises a step of producing water from the hydrogen fuel cell. In an embodiment, the water is used for water consumption in the electrochemical cell, recycled to an underground reservoir, or a combination thereof.

[0032] In an embodiment of the process herein, the alkali metal compound in the product solution comprises LiOH, NaOH, KOH, or any combination thereof.

[0033] In an embodiment of the process herein, the salt solution is an aqueous brine obtained from an underground deposit or reservoir. In an embodiment, the salt solution comprises LiCI, Li2SO4, Li3PO4, LiNOa, Lil, LiBr, NaCI, Na2SO4, Na3PO4, NaNOs, Nal, NBr, KOI, K2SO4, K3PO4, KNO3, KI, KBr, or any combination thereof.

[0034] In an embodiment of the process herein, the electrochemical cell is any one or more of the electrochemical cells as described herein, so long as an output stream of the electrochemical cell is hydrogen.

[0035] In an embodiment, the present disclosure relates to a process for producing an alkali metal compound comprising: receiving a salt solution in a solar-powered steam generator to produce steam and a salt solution concentrate; producing a condensate from the steam and delivering the condensate to an electrochemical cell, an underground reservoir, or a combination thereof; and delivering the salt solution concentrate to the electrochemical cell to produce a product solution comprising the alkali metal compound from the salt solution concentrate.

[0036] Other aspects and embodiments of the disclosure are evident in view of the detailed description provided herein.BRIEF DESCRIPTON OF THE DRAWINGS

[0037] Further advantages, permutations and combinations of the invention will now appear from the above and from the following detailed description of the various particularembodiments of the invention taken together with the accompanying drawings, each of which are intended to be non-limiting, in which:

[0038] FIG. 1 is a process flow diagram of an exemplary process for producing an alkali metal compound of the present disclosure comprising at least a solar-powered steam generator, a turbine fluidly coupled to the solar-steam powered generator and also comprising or coupled to a generator (electrical), and an electrochemical cell configured to receive a salt solution concentrate from the solar-powered steam generator.

[0039] FIG. 2 is a process flow diagram of an exemplary process for producing an alkali metal compound of the present disclosure comprising at least an electrochemical cell and a hydrogen fuel cell.

[0040] FIG. 3 is a schematic diagram of an exemplary chlor-alkali membrane electrolysis cell showing exemplary feed and product streams.

[0041] FIG. 4 is a schematic diagram of an exemplary chlor-alkali diaphragm electrolysis cell showing exemplary feed and product streams.

[0042] FIG. 5 is a schematic diagram of an exemplary 3-compartment electrolysis cell comprising a cation exchange membrane (GEM) and an anion exchange membrane (AEM), showing exemplary feed and product streams.

[0043] FIG. 6 is a schematic diagram of an exemplary multi-compartment cell comprising an optionally repeating unit consisting of a bipolar membrane and a GEM, showing exemplary feed and product streams. A 2-compartment embodiment is shown in FIG. 6, but the cell may comprise additional compartments in view of the optionally repeating unit.

[0044] FIG. 7 is a schematic diagram of an exemplary multi-compartment cell comprising an optionally repeating unit consisting of a bipolar membrane and an AEM, showing exemplary feed and product streams. A 2-compartment embodiment is shown in FIG. 7, but the cell may comprise additional compartments in view of the optionally repeating unit.

[0045] FIG. 8 is a schematic diagram of an exemplary multi-compartment cell comprising an optionally repeating unit consisting of a bipolar membrane, an AEM and aCEM, showing exemplary feed and product streams. A 3-compartment embodiment is shown in FIG. 8, but the cell may comprise additional compartments in view of the optionally repeating unit.

[0046] FIG. 9 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)).

[0047] FIG. 10 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))-

[0048] FIG. 11 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 (T) configured to consume a liquid reactant diffusing towards the GDL (panel (a)), and in another exemplary embodiment further comprising a mesh (panel (b)).

[0049] FIG. 12 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) there between (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)).

[0050] FIG. 13 is a schematic diagram of an exemplary 5-compartment membrane electrolysis cell with a gas diffusion electrode (“GDE”) in the cathode compartment, showing feed and product streams.

[0051] FIG. 14 is a schematic diagram of an exemplary 4-compartment membrane electrolysis cell with a GDE in the cathode compartment, showing feed and product streams.

[0052] FIG. 15 is a schematic diagram of an exemplary 3-compartment membrane electrolysis cell with a GDE in the cathode compartment, showing feed and product streams.

[0053] FIG. 16 is a schematic diagram of an exemplary 2-compartment membrane electrolysis cell with a GDE in the cathode compartment, showing feed and product streams.DETAILED DESCRIPTION

[0054] 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, exemplary suitable methods and materials are described herein.

[0055] The present disclosure pertains to processes and systems for producing an alkali metal compound. As used herein, the term “alkali metal compound” is intended to have interchangeably meaning with a base, both referring to any chemical compound that comprises an alkali metal (e.g. Li, Na, K, Rb, Cs, or Fr) in combination or association with one or more negatively charged molecules or anions (e.g. OFT, CO32). In an embodiment, the alkali metal compound is or comprises LiOH, NaOH, KOH, or a combination thereof. In a particular embodiment, the alkali metal compound is or comprises LiOH.

[0056] The processes and systems herein provide a number of advantages over existing technologies, in particular involving the combined use of electrochemical cells and generators (e.g. steam or power).

[0057] In certain embodiments herein, the processes and systems advantageously reduce or eliminate the wasteful evaporation of water into the atmosphere that occurs in existing processes, such as processes involving the extraction of lithium from brine. In certain embodiments herein, the processes and systems advantageously provide electrical power from previous waste streams, such as from water via a solar-powered generator fluidly coupled to a turbine and / or from hydrogen via an electrochemical cell fluidly coupled to a hydrogen fuel cell.

[0058] For example, rather than concentrating a salt solution (e.g. brine) in sequential ponds as is done for example in existing lithium processing procedures, a solar-powered steam generator may be used to receive the salt solution. By concentrating the solar energyof sunlight, the solar-powered steam generator boils off water within the salt solution and the steam is captured. The resulting products may then be used in a more ecofriendly manner by delivering the salt solution concentrate to an electrochemical cell for production of a product solution comprising desired alkali metal compounds and delivering the steam to other devices (e.g. a turbine) or back underground. When used to drive a turbine, the processes and systems herein are further advantageous in that the electrical power generated by a generator coupled to the turbine may be used to power the electrochemical cell and any condensate of the steam may likewise be used as a feedstream for the electrochemical cell or may be delivered back underground. Thus, the processes and systems herein provide significant improvements in the use of natural resources and are more ecofriendly manner than existing technologies.

[0059] In an embodiment, the present disclosure relates to a process for producing an alkali metal compound comprising receiving a salt solution in a solar-powered steam generator to produce steam and a salt solution concentrate; delivering the salt solution concentrate to an electrochemical cell; generating electrical power by directing at least a portion of the steam to a turbine coupled to a generator; and powering the electrochemical cell with the electrical power to produce a product solution comprising the alkali metal compound from the salt solution concentrate.

[0060] The present disclosure further provides exemplary systems to perform the processes disclosed herein. Thus, in an embodiment the present disclosure relates to a system comprising a solar-powered steam generator; an electrochemical cell fluidly coupled to the solar-powered steam generator; a turbine fluidly coupled to the solar-powered steam generator; and a generator coupled to the turbine to generate electrical power.

[0061] The processes and systems herein produce an alkali metal compound. In an embodiment, the produced alkali metal component is within a product solution. In an embodiment, the product solution (e.g. produced from the electrochemical) may comprise the desired alkali metal compound (e.g. LiOH) and be substantially free or free of any other alkali metal compounds. As used herein, by “substantially free” it is meant less than 10% by weight, more particularly less than 5% by weight, and more particularly still less than 1% by weight. In other embodiments, the product solution may comprise the desired alkali metal compound with other alkali metal compounds, minerals, and other compounds or components naturally present in the feed salt solution or added during the processing of thesalt solution. In such embodiments, the desired alkali metal compound is in higher amount or concentration that found in the feed salt solution and / or has been formed from other compounds, molecules and ions during processing in the electrochemical cell.

[0062] The processes disclosed herein involve a step of receiving a salt solution in a solar-powered steam generator to produce steam and a salt solution concentrate. Likewise, the system herein comprise a solar-powered steam generator, (see FIG. 1)

[0063] As used herein, the term “salt solution” refers to any aqueous solution of salts. The salt solution may be a naturally occurring solution, a synthetic solution, or a semi-synthetic solution. By “synthetic”, it is intended to mean that the salt solution was formed by combining individual ingredients (e.g. compounds, molecules, ions, etc.) to form the salt solution. By “semi-synthetic”, it is intended to mean that the salt solution is formed by adding one or more ingredients (e.g. compounds, molecules, ions, etc.) to a naturally occurring solution. The naturally occurring solution may already be a salt solution that is desired to be modified with other ingredients.

[0064] In an embodiment, the salt solution may be a produced water or brine that is extracted from an underground reservoir. By “produced water”, it is intended to mean a salt solution that is formed by delivering an aqueous fluid downhole to capture desirable components within the underground formation (e.g. lithium). By “brine”, it is intended to mean an existing underground aqueous solution containing desirable alkali metals. As used herein, the term “brine” may be used interchangeably with “salar brine” or “brine solution” and refer to the same solution, which is used for example, as the salt solution received in a solar-powered steam generator and / or an electrochemical cell. In an embodiment, the salt solution comprises LiCI, Li2SO4, Li3PO4, LiNOa, Lil, LiBr, NaCI, Na2SO4, NaaPO4, NaNOa, Nal, NBr, KOI, K2SO4, K3PO4, KNO3, KI, KBr, or a combination thereof. In an embodiment, the salt solution comprises LiCI, Li2SO4, LiaPC^, UNO3, Lil, LiBr. In a particular embodiment, the salt solution comprises LiCI.

[0065] In embodiments of the processes herein, the salt solution is received in a solar-powered steam generator (see FIG. 1 ). As used herein, the term “solar-powered steam generator” is intended to refer to a facility or an apparatus that uses energy from the sun to heat a fluid, thereby producing steam when the fluid is an aqueous fluid. As the skilled person will appreciate, solar-powered steam generators may go by different names in the industry,such as for example a solar receiver steam generator (SRSG) or a solar-powered boiler. Many designs and configurations of solar-powered steam generators are known and available. In simple terms, the solar-powered steam generator comprises a component for capturing sunlight (e.g. solar panels) and directing or concentrating the heat energy from the sunlight upon a fluid, to heat the fluid and generate a gaseous product (e.g. steam). In the context of the present disclosure, the solar-powered steam generator comprises a component to capture the steam and / or direct the steam to other equipment (e.g. a turbine). In the context of the present disclosure, the fluid that is heated by the solar-powered steam generator is a salt solution, such as a brine obtained from an underground reservoir.

[0066] In an embodiment, the solar-powered steam generator is powered by a solar parabolic trough, a solar dish, a solar power tower, or a linear Fresnel reflector, or a combination thereof. In a particular embodiment, the solar-powered steam generator is powered by a linear Fresnel reflector. Exemplary embodiments of a solar-powered steam generator include the Fresnel™ Solar Steam Generator (Fresnel; Germany); the SUNCNIM™ solar steam generator (Suncnim; France), the GE™ solar receiver steam generator (GE Renewable Energy; Switzerland), or the Victory Energy™ solar-powered boiler (Victory Energy; Oklahoma, USA). Many others would be known or could be identified by the skilled person for use in the processes and systems of the present disclosure.

[0067] In an embodiment of the processes and systems herein, the solar-powered steam generator is located at the site of extraction of a salt solution from an underground reservoir. In other embodiments, the salt solution may be transported short distances (e.g. by pipelines) or long distances (e.g. by transportation vehicles, such as trucks, trains or boats) from the site of extraction to the solar-powered steam generator.

[0068] In contrast to conventional processes in which the salt solution is delivered to a series of concentrating ponds, in the processes and systems herein the salt solution is ultimately delivered to the solar-powered steam generator. In an embodiment, the salt solution is delivered to a fluid storage container associated with the solar-powered steam generator. In an embodiment, the salt solution is delivered to piping associated with the solar-powered steam generator. Heat generated from the solar-powered steam generator is delivered to the salt solution to evaporate a portion of the water in the salt solution. As the water evaporates as steam, the salt solution becomes more concentrated with respect to compounds, minerals, molecules and ions contained within the salt solution. Some of thesecompounds, minerals, molecules and ions compounds may precipitate as their concentration increases. In an embodiment, the solar-powered steam generator comprises a series of different storage or processing tanks. In an embodiment, the solar-powered steam generator comprises different phases of piping. In these different storage or processing tanks and different phases of piping, the salt solution may be concentrated in series to capture different precipitated products in each tank or phase of piping.

[0069] As used herein, the term “salt solution concentrate” refers to a version of the salt solution that has higher concentrations of the therein contained salts than the salt solution. The salt solution concentrate may be any one or more of the concentrated salt solutions that are formed during processing by the solar-powered steam generator. In an embodiment, the salt solution concentrate comprises an increased concentration of one or more of LiCI, Li2SO4, Li3PO4, LiNO3, Lil, LiBr, NaCI, Na2SO4, Na3PO4, NaNO3, Nal, NBr, KCI, K2SO4, K3PO4, KNO3, KI, and KBr. In an embodiment, the salt solution concentrate comprises an increased concentration of one or more of one or more of LiCI, Li2SO4, Li3PO4, LiNO3, Lil, and LiBr. In a particular embodiment, the salt solution concentrate comprises an increased concentration of LiCI. As used herein, “increased concentration” is intended to mean a higher or greater concentration than in the feed salt solution.

[0070] In an embodiment of the processes disclosed herein, the salt solution concentrate may be pre-treated before it is delivered to an electrochemical cell. In an embodiment, the salt solution concentrate is pre-treated through one or more extraction stages (e.g. adsorption, ion exchange, membrane and / or solvent) and / or one or more precipitation stages. As used herein, the term “precipitation stage” is intended to refer to a chemical reaction resulting in the separation of one or more particular substances from a mixture based on the solubility of the mixture’s components through the deposition of the one or particular substances in solid form. In a further embodiment, the one or more extraction stages and / or one ore more precipitation stages comprises one or more pH adjustments of the salt solution concentrate. In an embodiment, the one or more pH adjustments comprises providing Na2CO3, H2SO4, Ca(OH)2, CaCO3, HCI, NaOH, CaO, or a combination thereof.

[0071] In an embodiment, the salt solution concentrate is pre-treated to remove divalent cations. In an embodiment, the divalent cations comprise Mg2+, Ca2+, or a combination thereof. In an embodiment, the salt solution concentrate is pre-treated to remove divalent cations by the one or more extraction stages and / or one or more precipitationstages. In an embodiment, the one or more extraction stages and / or one or more precipitation stages comprises precipitating Mg(OH)2, CaSC>4, 633(603)2, or a hydrate thereof, or any combination thereof.

[0072] In an embodiment, the salt solution concentrate is pre-treated to remove boron. In an embodiment, the salt solution concentrate is pre-treated to remove boron by the one or more extraction stages and / or one or more precipitation stages. In an embodiment, the one or more extraction stages and / or one or more precipitation stages comprises precipitating H3BO3, 633(663)2, or a hydrate thereof, or any combination thereof.

[0073] The steps of pre-treating the salt solution concentrate may be performed by or within one or more pre-treatment components of the system herein. As used herein, by “pre-treatment component” it is intended to refer to any device, apparatus or facility that may be used for pre-treating the salt solution concentrate. In an embodiment, the pre-treatment component is a device that delivers and / or mixes the pre-treatment ingredient (e.g. a pH adjuster, such as Na2CO3, H2SO4, 6a(OH)2, 6a6O3, HCI, NaOH, CaO). In an embodiment, the pre-treatment component is a device that captures a precipitate produced by adding a pre-treatment ingredient to the salt solution concentrate. Examples of pre-treatment components may includes storage vessels, conduits that deliver and / or remove substances from the salt solution concentrate, trays that capture precipitate, or any other suitable device or apparatus for achieving the purpose of the pre-treatment step.

[0074] The processes disclosed herein involve a step of delivering the salt solution concentrate to an electrochemical cell. Likewise, the system herein comprises an electrochemical cell, (see FIG. 1 )

[0075] As contemplated herein, the electrochemical cell may be any form of electrochemical cell suitable for the processes and systems disclosed herein. The skilled person will appreciate that various types of electrochemical cells exist. Exemplary electrochemical cells are described herein below.

[0076] In an embodiment, the electrochemical cell is an electrodialysis cell as described herein. In an embodiment, the electrochemical cell is a membrane electrochemical cell as described herein. In an embodiment, the electrochemical cell is a membrane electrochemical cell comprising a gas diffusion electrode (GDE) as described herein. In anembodiment, the electrochemical cell is a membrane electrochemical cell comprising a GDE and having four or five compartments.

[0077] The electrochemical cell is configured to receive the salt solution concentrate from the solar-powered steam generator. In an embodiment, the electrochemical cell is fluidly coupled to the solar-powered steam generator. As used herein, the term “fluidly coupled” has its plain and ordinary meaning in that the components are interconnected in such a way that fluid or gas is able to pass from one to the other. In an embodiment, the salt solution concentrate may be delivered directly from the solar-powered steam generator to the electrochemical cell, such as via piping interconnecting the two components. In an embodiment, the solar-powered steam generator and the electrochemical are arranged together in a single apparatus. In other embodiments, the components are in close proximity to each other (e.g. on the same project site), but do not form a single apparatus. For example, the solar-powered steam generator and the electrochemical cell may be at different buildings or facilities at the same project site.

[0078] In other embodiments, the salt solution concentrate may be transported short distances (e.g. by pipelines) or long distances (e.g. by transportation vehicles, such as trucks, trains or boats) from the solar-powered steam generator to the electrochemical cell.

[0079] Exemplary flow rates and temperatures of the salt solution concentrate for processing in the electrochemical cells are described elsewhere herein. The skilled person will appreciate that the flow rate and temperature may be altered depending on the type of electrochemical cell that is used, the desired product solution, the desired alkali metal compound, the feed inputs, etc.

[0080] The alkali metal compound produced by the processes and systems herein is dependent on the composition of the salt solution concentrate. In embodiments of the present disclosure employing a membrane electrolysis cell as the electrochemical cell, if the salt solution concentrate comprises LiCI, Li2SO4, Li3PO4, UNO3, or Lil, then LiOH will be produced in the base build-up compartment and HOI, H2SO4, H3PO4, HNO3, HI, respectively, will be produced simultaneously in the acid build-up compartment. Likewise, if the salt solution concentrate comprises NaCI, Na2SO4, Na3PO4, NaNOs, or Nal, then NaOH will be produced in the base build-up compartment and HOI, H2SO4, H3PO4, HNO3, HI, respectively, will be produced simultaneously in the acid build-up compartment. And, if the salt solutioncomprises KCI, K2SO4, K3PO4, KNO3, or KI, then KOH will be produced in the base build-up compartment and HOI, H2SO4, H3PO4, HNO3, HI, respectively, will be produced simultaneously in the acid build-up compartment.

[0081] In an embodiment, a feed input to the electrochemical cell is water. In an embodiment, the water or a portion thereof may be delivered to the electrochemical cell from the solar-powered steam generator. In such embodiments, the solar-powered steam generator may be interconnected to or comprise a cooling device to condense at least a portion of the formed steam into water. The cooling device may be any device or apparatus suitable for reducing the temperature of the steam to convert it to liquid form. In an embodiment, the cooling device is one or a series of tubing or glassware to which a cooling temperature is applied to an external surface to condense the internalized steam to water. In an embodiment, the tubing or glassware is surrounded by a thermal-controlled jacket having a temperature of less than 100°C to supply the cooling temperature, more particularly less than 25°C, more particularly still less than 10°C, and more particularly still less than 0°C. In an embodiment, the cooling system is a steam jet cooling system.

[0082] In an embodiment, the cooling device is a structure that permits exposure of the steam to ambient temperature on-site. Although this approach may not condense the steam to water as quickly as supplying a cooling temperature, it may represent a more ecofriendly approach since it does not require generation of cooled temperatures.

[0083] The cooling device may comprise a component for collecting the condensate. As an example, the cooling device may comprise a vessel for storing the condensate.

[0084] In embodiments of the processes and systems herein in which a portion of the steam is cooled and the condensate is delivered to the electrochemical cell, the electrochemical cell is configured to receive the condensate from the cooling device. In an embodiment, the condensate may be delivered directly from the cooling device to the electrochemical cell, such as via piping interconnecting the two components. In an embodiment, the cooling device and the electrochemical are arranged together in a single apparatus. In other embodiments, the components are in close proximity to each other (e.g. on the same project site), but do not form a single apparatus. For example, the cooling device and the electrochemical cell may be at different buildings or facilities at the same project site.

[0085] In other embodiments, the condensate may be transported short distances (e.g. by pipelines) or long distances (e.g. by transportation vehicles, such as trucks, trains or boats) from the cooling device to the electrochemical cell. This may be the same or a different transportation vehicle than is used to transport the salt solution concentrate from the solar-powered steam generator to the electrochemical cell.

[0086] In embodiments of the processes and systems herein in which a portion of the steam is cooled to form condensate, all or a portion of the water may instead be delivered to an underground reservoir rather than the electrochemical cell. Such embodiments may provide an ecofriendly solution to the removal of the salt solution (e.g. brine) from the underground reservoir since at least a portion of the aqueous component that was removed can be restored to the underground reservoir. In other embodiments, the condensate may be used for any other purpose, such as further processing to provide drinking water or water that can be used in other processes or to form other products.

[0087] In certain embodiments, the processes disclosed herein involve a step of generating electrical power by directing at least a portion of the steam to a turbine coupled to a generator. Likewise, the system herein comprise a turbine and a generator, (see FIG. 1 )

[0088] As the skilled person will appreciate, although the turbine and generator components are referred to separately herein, often these components are manufactured, sold and used as a single device or apparatus commonly referred to as a “steam turbine” or a “steam turbine driven generator”. Thus, as used herein, the terms “turbine” and “generator” encompass both the components as separate and distinct units and the components combined as a steam turbine. As used herein, the term “coupled to” encompasses both of these arrangements. By “coupled to”, it is meant that the turbine and the generator are interconnected in a manner to generate electrical power from steam. In an embodiment, the turbine and the generator are arranged together in a single apparatus (i.e. a steam turbine). In other embodiments, the components are in close proximity to each other (e.g. within the same building), but do not form a single apparatus.

[0089] For ease of reference in the following disclosure, the term “steam turbine” will be used to encompass both configurations. As the skilled person will appreciate, there are many different types of steam turbines that may be used in the practice of the presentdisclosure. A steam turbine is a device, apparatus or machine that uses a turbine to extract thermal energy from steam, namely pressurized steam, and uses it to do mechanical work on a rotating output shaft that is interconnected to a generator to produce electrical power. In the generator, the mechanical energy (e.g. rotational energy) is transformed into electrical energy, such as by coiled wires spinning inside a magnetic field thereby causing an electric current to flow through the wire.

[0090] Generally, as steam passes through a turbine’s spinning blades, it expands and cools, releasing the majority of the energy it contains. Because of the steam, the blades are constantly spinning so long as steam is supplied. As a result, the blades convert the vast majority of the steam’s potential energy into kinetic energy. In the context of the present disclosure, the turbine is then used to power a generator which produces electricity. The most basic components of a turbine of the present disclosure are the blades, rotors and rotational output (e.g. axle). In embodiments herein, the blades or each stage of blades have steam inlets and outputs. The inlets are configured to allow steam to be delivered to the blades and drive rotation. The outputs are configured to allow the condensate (i.e. water) to escape from the blades of the turbine.

[0091] In an embodiment, the turbine of the present disclosure is an impulse steam turbine. In an embodiment, the turbine of the present disclosure is a reaction steam turbine. In an embodiment, the turbine of the present disclosure is a single cylinder turbine. In an embodiment, the turbine of the present disclosure is a multiple cylinder turbine. In an embodiment, the turbine of the present disclosure is an axial flow turbine, a radial flow turbine, a tangential flow turbine, or any combination thereof. In an embodiment, the turbine of the present disclosure is a single pressure turbine, a reheat turbine, a dual pressure turbine, or any combination thereof. In an embodiment, the turbine of the present disclosure is a condensing turbine.

[0092] In embodiments of the processes and systems herein, the turbine is configured to receive at least a portion of the steam that is produced by the solar-powered steam generator. In an embodiment, the turbine is fluidly coupled to the solar-powered steam generator. As used herein, the term “fluidly coupled” has its plain and ordinary meaning in that the components are interconnected in such a way that fluid or gas is able to pass from one component to the other. In an embodiment, the stream may be delivered directly from the solar-powered steam generator to the turbine, such as via piping interconnecting the twocomponents. In an embodiment, the solar-powered steam generator and the turbine are arranged together in a single apparatus. In other embodiments, the components are in close proximity to each other (e.g. on the same project site), but do not form a single apparatus. For example, the turbine and solar-powered steam generator may be at different buildings or facilities at the same project site.

[0093] Exemplary embodiments of a steam turbine of the present disclosure includes, without limitation, those manufactured and sold by Bradken, Inc., GE Power, Siemens Energy Inc., Mitsubishi Heavy Industries America, Inc., Turboatom, Bharat Heavy Electricals Limited, Turbopar Group, Shanghai Electric Group Corp., and Dongfang Electric Corporation Ltd., which are a few of the largest steam turbine manufactures in the world by active capacity. In an embodiment, the steam turbine produces a power output in a range between about 1 MW and about 1 GW, more particularly between about 2 MW and 500 MW, and more particularly still between about 2 MW and 250 MW. In an embodiment and without limitation, the steam turbine is the SST-400, SST-500, SST-600, SST-700 / 900 or SST-800 (Siemens Energy).

[0094] In certain embodiments, the processes disclosed herein involve a step of powering the electrochemical cell with the electrical power provided by the steam turbine to produce a product solution comprising the alkali metal compound from the salt solution concentrate.

[0095] As used herein, the term “product solution” is intended to refer to an output stream of the electrochemical cell that comprises the desired alkali metal compound or base. The electrochemical cell is configured to provide the product solution, for example by having an output port or an elution portion. In an embodiment, the product solution is an output from a cathode compartment (see e.g. FIGs. 3-5). In an embodiment, the product solution is an output from a compartment positioned between a GEM and a BPM (see e.g. FIGs. 6-8). In an embodiment, the product solution is an output from a base build-up compartment (see e.g. FIGs. 13-15). As described elsewhere herein, the product solution may comprise the desired alkali metal compound (e.g. LiOH) and be substantially free or free of any other alkali metal compounds. In other embodiments, the product solution may comprise the desired alkali metal compound with other alkali metal compounds, minerals, and other compounds or components naturally present in the feed salt solution or added during the processing of the salt solution.

[0096] By “powering the electrochemical cell”, it is meant to provide the electrical current for electrolysis to occur within the electrochemical cell. The electrochemical cell is configured to receive the electrical power from the grid and / or generator. In an embodiment, the electrical power may be delivered directly from the generator to the electrochemical cell, such as via electrical cables extending directly from the generator to the electrochemical cell. In an embodiment, the electrical power may be delivered to another facility, device or apparatus before it is delivered to the electrochemical cell. For example, in an embodiment, the electricity is delivered to an intermediary device, such as a battery, as capacitor, or some other form of electrical power storage or regulation device. In an embodiment, the electrical power is delivered to a facility for processing the electricity before it is delivered to the electrochemical cell.

[0097] In an embodiment, the generator and the electrochemical cell are arranged together in a single apparatus. In other embodiments, the generator and the electrochemical cell are in close proximity to each other (e.g. on the same project site), but do not form a single apparatus. In other embodiments, the electricity from the generator may be transported short distances or long distances from the generator to the electrochemical cell, such as by underground or above ground electrical cables.

[0098] In an embodiment, the electrical power produced from the generator is sold to the grid.

[0099] In some embodiments of the processes and systems herein, the condensate from the turbine may be delivered to the electrochemical cell as a feedstock for consumption by the electrochemical cell. The turbine may comprise a component for collecting the condensate. As an example, the turbine may comprise a vessel, tank or other storage apparatus for storing the condensate.

[0100] In embodiments of the processes and systems herein in which condensate from the turbine is delivered to the electrochemical cell, the electrochemical cell is configured to receive the condensate from the turbine. In an embodiment, the condensate may be delivered directly from the turbine to the electrochemical cell, such as via piping interconnecting the two components. In an embodiment, the turbine and the electrochemical are arranged together in a single apparatus. In other embodiments, the components are in close proximity to each other (e.g. on the same project site), but do not form a singleapparatus. For example, the turbine and the electrochemical cell may be at different buildings or facilities at the same project site.

[0101] In other embodiments, the condensate may be transported short distances (e.g. by pipelines) or long distances (e.g. by transportation vehicles, such as trucks, trains or boats) from the turbine to the electrochemical cell. This may be the same or a different transportation vehicle than is used to transport the salt solution concentrate from the solar-powered steam generator or the condensate from the cooling device to the electrochemical cell.

[0102] In embodiments of the processes and systems herein, all or a portion of the condensate generated by the turbine may instead be delivered to an underground reservoir rather than the electrochemical cell. Such embodiments may provide an ecofriendly solution to the removal of the salt solution (e.g. brine) from the underground reservoir since at least a portion of the aqueous component that was removed can be restored to the underground reservoir. In other embodiments, the condensate from the turbine may be used for any other purpose, such as further processing to provide drinking water or water that can be used in other processes or to form other products.

[0103] In an embodiment, the processes herein may further comprise at step of crystallizing the alkali metal compound from the product solution. Likewise, the systems herein may comprise a crystallization unit (e.g. a device or apparatus).

[0104] The crystallizing may be by any suitable means to obtain the separated and solid-form alkali metal compound from the product solution, including but not limited to: mixing, stirring, blending, or agitating the product solution; heating the product solution to evaporate a quantity of the solvent; providing an additional chemical to the product solution; or any combination thereof. The crystallization unit may be any structure or component capable of performing these functions or a vessel or container in which such functions are performed. Exemplary embodiments of crystallizers and crystallization units of the present disclosure include, without limitation, those manufactured and sold by Alaqua Inc., BiOZEEN, Chem Process Systems, CMM Group, Condorchem Envitech, Paul Mueller Company, Radhe Techno, Rosenblad Design Group, Veolia, and Vobis, which are a few of the largest steam turbine manufactures in the world by active capacity.

[0105] In an embodiment, the product solution comprises LiOH, NaOH, KOH, HOI, Cl2, H2, LiCI, Li2SO4, Li3PO4, LiNO3, Lil, LiBr, NaCI, Na2SO4, Na3PO4, NaNO3, Nal, NBr, KOI, K2SO4, K3PO4, KNO3, KI, KBr, or a combination thereof. In a particular embodiment, the product solution comprises at least LiOH.

[0106] In another embodiment, the present disclosure relates to a process for producing an alkali metal compound comprising: receiving a salt solution in an electrochemical cell comprising a cathode and an anode; applying an electrical potential between the cathode and anode; producing hydrogen gas at the cathode; producing from the electrochemical cell a product solution comprising the alkali metal compound; and delivering the hydrogen gas to a hydrogen fuel cell to generate electrical power.

[0107] The processes disclosed herein involving a hydrogen fuel cell include a step of receiving a salt solution in an electrochemical cell comprising a cathode and an anode. The salt solution may be any salt solution, including without limitation any salt solution as described earlier, including without limitation a brine. The salt solution may also be the salt solution concentrate as described herein. The salt solution may also be modified by a pretreatment step, such as those described herein without limitation.

[0108] In an embodiment, the salt solution comprises LiCI, Li2SO4, Li3PO4, LiNO3, Lil, LiBr, NaCI, Na2SO4, Na3PO4, NaNO3, Nal, NBr, KCI, K2SO4, K3PO4, KNO3, KI, KBr, or a combination thereof. In an embodiment, the salt solution comprises LiCI, Li2SO4, Li3PO4, LiNO3, Lil, LiBr. In a particular embodiment, the salt solution comprises LiCI.

[0109] In the context of the processes involving a hydrogen fuel cell, the electrochemical cell may be any electrochemical cell as described herein, so long as an output stream of the electrochemical cell is hydrogen. The skilled person will appreciate that various types of electrochemical cells exist, such as those described below herein without limitation. Exemplary electrochemical cells are described herein below, of which at least the electrochemical cells of FIGs. 3-8 produce hydrogen. It is contemplated herein that the other electrochemical cells may be modified to product hydrogen.

[0110] In an embodiment of the processes herein involving a hydrogen fuel cell, the electrochemical cell is located at the site of extraction of a salt solution from an underground reservoir, a site where a salt solution is pre-treated, a site where a salt solution is concentrated (e.g. such as by a solar-powered steam generator as described herein), or anyother processing site. In other embodiments, the salt solution may be transported short distances (e.g. by pipelines) or long distances (e.g. by transportation vehicles, such as trucks, trains or boats) from any of these sites to the location of the electrochemical cell.

[0111] The salt solution is received by the electrochemical cell as an input stream. The electrochemical cell is configured to receive the salt solution, for example by having an input port. In an embodiment, the salt solution is received into an anode compartment (see e.g. FIGs. 3-4, 15 and 16). In an embodiment, the salt solution is received into a compartment positioned between an AEM and a GEM (see e.g. FIGs. 5, 7-8, 13-14). In an embodiment, the salt solution is received into a compartment positioned between a BPM and a GEM (see e.g. FIG. 6).

[0112] The processes disclosed herein involving a hydrogen fuel cell include a step of applying an electrical potential between the cathode and anode. The electrical potential is provided by delivering electrical power to the electrochemical cell.

[0113] In an embodiment, the electrochemical power that is delivered to the electrochemical cell to apply the electrical potential between the cathode and the anode is from an external power grid, a steam turbine as described herein, a renewable energy source, or, once the process is in operation, from a closed-circuit connectivity with the hydrogen fuel cell. In an embodiment, the electrical power may be exclusively from any one of these or other sources. In an embodiment, the electrical power may be from any combination or these and other sources.

[0114] In an embodiment, once the process disclosed herein uses a start-up amount of electrical power from a source other than the hydrogen fuel cell, the electrochemical cell may subsequently be powered exclusively by electrical power generated by the hydrogen fuel cell, to form a closed circuit. Advantageously, if there is already at least one of the processes underway, a second process may be commenced without the start-up amount of electrical power from a source other than the hydrogen fuel cell, by using electrical power from a hydrogen fuel cell of another process already in operation. In this regard, in the processes herein, the electrical power from a single hydrogen fuel cell may be delivered and used to power more than one electrochemical cell. Likewise, once more than one electrochemical cell is in operation, the hydrogen from multiple electrochemical cells may be delivered to a single hydrogen fuel cell to generate electrical power.

[0115] The processes disclosed herein involve a step of producing hydrogen gas at the cathode. In this regard, the electrochemical cell employed in these processes should be one that emits hydrogen. The appropriate electrochemical cell may be configured to provide the hydrogen, for example by having a hydrogen output port. In an embodiment, the hydrogen output port is an output from a cathode compartment (see e.g. FIGs. 3-7).

[0116] The processes disclosed herein involve a step of producing from the electrochemical cell a product solution comprising the alkali metal compound.

[0117] As described elsewhere herein, the term “product solution” is intended to refer to an output stream of the electrochemical cell that comprises the desired alkali metal compound or base. The electrochemical cell is configured to provide the product solution, for example by having an output port or an elution portion. The product solution may comprise the desired alkali metal compound (e.g. LiOH) and be substantially free or free of any other alkali metal compounds. In other embodiments, the product solution may comprise the desired alkali metal compound with other alkali metal compounds, minerals, and other compounds or components naturally present in the feed salt solution or added during the processing of the salt solution.

[0118] The processes disclosed herein involve a step of delivering the hydrogen gas from the electrochemical cell to a hydrogen fuel cell to generate electrical power.

[0119] In embodiments of the processes herein, the electrochemical cell is fluidly coupled to the hydrogen fuel cell. As used herein, the term “fluidly coupled” has its plain and ordinary meaning in that the components are interconnected in such a way that fluid or gas is able to pass from one component to the other. In an embodiment, the hydrogen gas may be delivered directly from the electrochemical cell to the hydrogen fuel cell, such as via piping interconnecting the two components. In an embodiment, the electrochemical cell and the hydrogen fuel cell are arranged together in a single apparatus. In other embodiments, the components are in close proximity to each other (e.g. on the same project site), but do not form a single apparatus. For example, the electrochemical cell and hydrogen fuel cell may be at different buildings or facilities at the same project site. In other embodiments, the hydrogen gas may be transported short distances (e.g. by pipelines) or long distances (e.g. by transportation vehicles, such as trucks, trains or boats) from any of these sites to the location of the electrochemical cell.

[0120] As the skilled person will appreciate, there are many different types of hydrogen fuel cells that may be used in the practice of the present disclosure. These devices are also known as hydrogen-powered generators or hydrogen fuel cell generators. Generally, a hydrogen fuel cell is composed of an anode, cathode, and an electrolyte membrane. A typical hydrogen fuel cell works by passing hydrogen through the anode of a fuel cell and oxygen through the cathode. At the anode site, a catalyst splits the hydrogen molecules into electrons and protons. The protons pass through the porous electrolyte membrane, while the electrons are forced through a circuit, generating an electric current and excess heat. At the cathode, the protons, electrons, and oxygen combine to produce water molecules.

[0121] Exemplary embodiments of a hydrogen fuel cell of the present disclosure includes, without limitation, those manufactured or being developed by Solvay, dSpace, FuelCell Energy, TO Energy, DuPont de Nemours, Inc., Air Products & Chemicals, Inc., Bloom Energy Corporation, and Plug Power, Inc.

[0122] In the processes herein involving the use of a hydrogen fuel cell, the hydrogen is delivered from an electrochemical cell to a hydrogen fuel cell to advantageously provide an ecofriendly solution to hydrogen gas formed by electrochemical cells. The hydrogen fuel cell converts the waste hydrogen from the electrochemical cell to electrical power and water, both of which can by cycled back and used by the electrochemical cell.

[0123] Thus, in an embodiment, the processes disclosed herein involving the use of a hydrogen fuel cell include a step of powering the electrochemical cell from the grid and / or with the electrical power provided by the hydrogen fuel cell to produce more product solution from the electrochemical cell.

[0124] By “powering the electrochemical cell”, it is meant to provide the electrical current for electrolysis to occur within the electrochemical cell. In some embodiments, the electrochemical cell is configured to receive the electrical power from the hydrogen fuel cell. In an embodiment, the electrical power may be delivered directly from the hydrogen fuel cell to the electrochemical cell, such as via electrical cables extending directly from the hydrogen fuel cell to the electrochemical cell. In an embodiment, the electrical power may be delivered to another facility, device or apparatus before it is delivered to the electrochemical cell. For example, in an embodiment, the electricity is delivered to an intermediary device, such as abattery, as capacitor, or some other form of electrical power storage or regulation device. In an embodiment, the electrical power is delivered to a facility for processing the electricity before it is delivered to the electrochemical cell.

[0125] In an embodiment, the hydrogen fuel cell and the electrochemical cell are arranged together in a single apparatus. In other embodiments, the hydrogen fuel cell and the electrochemical cell are in close proximity to each other (e.g. on the same project site), but do not form a single apparatus. In other embodiments, the electricity from the hydrogen fuel cell may be transported short distances or long distances from the hydrogen fuel cell to the electrochemical cell, such as by underground or above ground electrical cables.

[0126] In some embodiments of the processes herein involving the use of a hydrogen fuel cell, the water generated from the hydrogen fuel cell may be delivered to the electrochemical cell as a feedstock for consumption by the electrochemical cell. The hydrogen fuel cell may comprise a component for collecting the water. As an example, the hydrogen fuel cell may comprise a vessel, tank or other storage apparatus for storing the water.

[0127] In embodiments of the processes herein in which waterfrom the hydrogen fuel cell is delivered to the electrochemical cell, the electrochemical cell is configured to receive the water from the hydrogen fuel cell. In an embodiment, the water may be delivered directly from the hydrogen fuel cell to the electrochemical cell, such as via piping interconnecting the two components. In an embodiment, the hydrogen fuel cell and the electrochemical are arranged together in a single apparatus. In other embodiments, the components are in close proximity to each other (e.g. on the same project site), but do not form a single apparatus. For example, the hydrogen fuel cell and the electrochemical cell may be at different buildings or facilities at the same project site.

[0128] In other embodiments, the water may be transported short distances (e.g. by pipelines) or long distances (e.g. by transportation vehicles, such as trucks, trains or boats) from the hydrogen fuel cell to the electrochemical cell. This may be the same or a different transportation vehicle than is used to transport the salt solution to the electrochemical cell.

[0129] In embodiments of the processes and systems herein involving a hydrogen fuel cell, all or a portion of the water generated by the hydrogen fuel cell may instead be delivered to an underground reservoir rather than the electrochemical cell. Suchembodiments may provide an ecofriendly solution to the removal of the salt solution (e.g. brine) from the underground reservoir since at least a portion of the aqueous component that was removed can be restored to the underground reservoir. In other embodiments, the water from the hydrogen fuel cell may be used for any other purpose, such as further processing to provide drinking water or water that can be used in other processes or to form other products.

[0130] Electrochemical Cells

[0131] As described earlier herein, the term “electrochemical cell” refers to any device comprising an anode and a cathode, whereby electrons move in response to an electrical energy being current being supplied to facilitate chemical reactions within the electrochemical cell.

[0132] In an embodiment, the electrochemical cell is an electrodialysis cell or a membrane electrolysis cell, these terms used interchangeably herein. As the skilled person will appreciate, an electrodialysis cell is a form of an electrochemical cell that can be used to transport salts from one solution or compartment to another. An electrodialysis cell comprises one or more membranes separating different compartments of the electrodialysis cell. Using an electrodialysis cell, electrolysis is used to transport salt ions from one solution or compartment through ion-exchange membranes to another solution or compartment under the influence of an applied electric potential difference.

[0133] In an embodiment, the membrane electrolysis cell may comprise one compartment, two compartments, three compartments, four compartments, five compartments, or more. The compartments may, for example be separated by membranes and / or diaphragms. In an embodiment, one or more compartments of the membrane electrolysis cell comprise an anode compartment, an acid build-up compartment, a salt depletion compartment, a base build-up compartment, a cathode compartment, or any combination thereof. The “anode compartment” is the compartment comprising an anode. The “cathode compartment” is the compartment comprising the cathode. The “salt-depletion compartment” is a compartment from which salts from the salt solution or salt solution concentrate are removed. The “acid build-up compartment is a compartment in which acidic species or solutions reside and can be obtained upon operation. The “base build-up compartment” is a compartment in which basic species or solutions reside and can beobtained upon operation. For example, the base build-up compartment may comprise the desired alkali metal compounds of the present disclosure. In a particular embodiment, the membrane electrolysis cell comprises four compartments or five compartments.

[0134] In an embodiment, the electrochemical cell may be a chlor-alkali membrane electrolysis cell (see FIG. 3) or a chlor-alkali diaphragm electrolysis cell (see FIG. 4). As shown in FIG. 3, a chlor-alkali membrane electrolysis cell comprises a cation exchange membrane (GEM). The GEM permits the passage of cations, such as Li+, through the membrane while preventing passage of other substances, including the salt solution. In contrast, as shown in FIG. 4, a chlor-alkali diaphragm electrolysis cell comprises a membrane or diaphragm that is semi-permeable and allows both the cations and the salt solution to pass through. With a salt solution comprising LiCI, both of these electrochemical cells allow for the formation of LiOH, but with the chlor-alkali membrane cell the base (e.g. LiOH) is in aqueous solution whereas with the chlor-alkali diaphragm the base (e.g. LiOH) is in the dilute salt solution. Both of these types of electrochemical cells produce hydrogen (H2) as a by-product.

[0135] In another embodiment, the electrochemical cell may be an electrodialysis cell that comprises both a GEM and an anion exchange membrane (AEM), such as for example shown in FIG. 5. The embodiment shown in FIG. 5 is an electrochemical cell having three compartments, each compartment separated by a membrane. In other embodiments, the electrochemical cell may have four compartments, five compartments, or more. Different configurations may be used to obtain different outputs and / or utilize different inputs / feedstocks.

[0136] Exemplary embodiments of AEMs and CEMs that may be used in the context of the present disclosure are described elsewhere herein.

[0137] In an embodiment, the electrochemical cell may be an electrodialysis cell that comprises at least one bipolar membrane (BPM), such as for example shown in FIG. 6. As used herein, by “bipolar membrane” it is intended to mean a membrane that is used to split water. In an embodiment, the BPM is a sandwich of a GEM and an AEM to form a single BPM. Since a BPM allows both anions and cations to pass, these membranes are not typically considered to split the electrodialysis cell into different compartments.

[0138] In an embodiment, the electrochemical cell may comprise a single BPM separating one or more OEMs and / or AEMs on either side. For example, in an embodiment the electrolysis cell may comprise the following arrangement of membranes: AEM-CEM- BPM-AEM-CEM.

[0139] In an embodiment, the electrochemical cell may comprise two BPMs separated by a CEM (e.g. BPM-CEM-BPM; see FIG. 6). In an embodiment, the electrochemical cell may comprise two bipolar membranes separated by an AEM (e.g. BPM- AEM-BPM; see FIG. 7). In an embodiment, the electrochemical cell may comprise two membranes separated by an AEM and a CEM (e.g. BPM-AEM-CEM-BPM; see FIG. 8). Repeating units of any of these configurations within an electrochemical cell is contemplated and encompassed herein, such as for example BPM-CEM-BPM-CEM-BPM.

[0140] In an embodiment, the membrane electrolysis cell comprises a gas diffusion electrode (“GDE”) in the cathode compartment. In a particular embodiment of the membrane electrolysis cell, the membrane electrolysis cell comprises the GDE as the cathode in the cathode compartment.

[0141] The GDE comprises a porous catalyst layer which is disposed on a 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 ( .e. catalyst) are contacted.

[0142] In an embodiment, the gas may comprise oxygen and the liquid may comprise water resulting in the cathodic reaction:O2+ 2H2O + 4e- -► 4OH-

[0143] 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).

[0144] In a further embodiment, the gas may comprise oxygen admixed with carbon dioxide resulting in the following cathodic reactions:O2+ 2H2O + 4e- -► 4OH-OH- + CO2-► HCO3-HCO3- + OH- -► CO32- + H2O

[0145] In this embodiment, it may be possible to electrochemically produce alkali metal carbonates and bicarbonates.

[0146] 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. 9 (GDE-1), FIG. 10 (GDE-2), FIG.11 (GDES) and FIG. 12 (GDES).

[0147] 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

[0148] 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. 9(a).

[0149] 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 anembodiment, 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. 9(b).

[0150] 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. 9(c)) or opposite from the MPL (see, for example, FIG. 9(d)). In an embodiment, the mesh is bonded to the GDL by teflonization, hot-pressing, or lamination.

[0151] 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. 9(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.GDE-2

[0152] 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. 10(a).

[0153] 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.

[0154] 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. 10(b).

[0155] 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. 10(c)) or opposite from theMPL (see, for example, FIG. 10(d)). In an embodiment, the mesh is bonded to the GDL by teflonization, hot-pressing, or lamination.GDE-3

[0156] 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 (T) optimized to substantially or completely consume a liquid reactant diffusing across the CL before reaching the GDL. See, for example, see FIG. 1 1 (a).

[0157] 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.

[0158] 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. 11 (b)). In an embodiment, the mesh is bonded to the GDL by teflonization, hot-pressing, or lamination.GDE-4

[0159] 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 furtherembodiment, 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. 12(a).

[0160] 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. 12(b).

[0161] 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. 12(c) or (d)).

[0162] 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.

[0163] The surfaces of any of the GDEs described herein may have an embossed / debossed pattern to effectively increase the active surface area. The pattern may be applied to the GDEs 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.

[0164] 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)

[0165] 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 itsthickness 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.

[0166] The GDL may have a thickness of between 50 pm and 1000 pm, between 50 pm and 950 pm, between 50 pm and 900 pm, between 50 pm and 850 pm, between50 pm and 800 pm, between 50 pm and 750 pm, between 50 pm and 700 pm, between50 pm and 650 pm, between 50 pm and 600 pm, between 50 pm and 550 pm, between50 pm and 500 pm, between 50 pm and 450 pm, between 50 pm and 400 pm, between50 pm and 350 pm, between 50 pm and 300 pm, between 50 pm and 250 pm, between50 pm and 200 pm, between 50 pm and 150 pm, between 50 pm and 100 pm, between100 pm and 1000 pm, between 150 pm and 1000 pm, between 200 pm and 1000 pm, between 250 pm and 1000 pm, between 300 pm and 1000 pm, between 350 pm and 1000 pm, between 400 pm and 1000 pm, between 450 pm and 1000 pm, between 500 pm and 1000 pm, between 550 pm and 1000 pm, between 600 pm and 1000 pm, between 650 pm and 1000 pm, between 700 pm and 1000 pm, between 750 pm and 1000 pm, between 800 pm and 1000 pm, between 850 pm and 1000 pm, between 900 pm and 1000 pm, between 950 pm and 1000 pm, between 100 pm and 950 pm, between 150 pm and 900 pm, between 200 pm and 850 pm, between 250 pm and 800 pm, between 300 pm and 750 pm, between 350 pm and 700 pm, between 400 pm and 650 pm, between 450 pm and 600 pm, between 500 pm and 550 pm, between 200 pm and 400 pm, between 210 pm and 390 pm, between 220 pm and 380 pm, between 230 pm and 370 pm, between 240 pm and 360 pm, between 250 pm and 350 pm, between 260 pm and 340 pm, between 270 pm and 330 pm, between 280 pm and 320 pm, or between 290 pm and 310 pm.

[0167] The GDL may have an average pore diameter of between 1 pm and 100 pm, between 1 pm and 90 pm, between 1 pm and 80 pm, between 1 pm and 70 pm, between 1 pm and 60 pm, between 1 pm and 50 pm, between 1 pm and 40 pm, between 1 pm and 30 pm, between 1 pm and 20 pm, or between 1 pm and 10 pm.

[0168] 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% and95%. between 55% and 90%, between 60% and 85%, between 65% and 80%, or between 70% and 75%.

[0169] 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).

[0170] Non-limiting examples of carbon-fibre paper include:(la) Toray TGP-H carbon-fibre paper (e.g. TGP-H-030, TGP-H-060, TGP-H-090, TGP-H-120),(lb) 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),(lc) Spectracarb™ carbon-fibre paper (e.g. 2050A-0850, 2050A-1050, 2050A- 1535, 2050A-1550, 2050A-1550 Treated),(ld) Freudenberg carbon-fibre paper (e.g. H14, H14C7, H14C9, H14C10, H14Cx653, H15, H15C13, H15C14, H23, H23C2, H23C3, H23C5, H23C6, H23C7, H23C8, H23C9, H23Cx653, H23I2),(le) 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),(lf) CeTech carbon-fibre paper (e.g. GDS180S, GDS210, GDS230, GDS 250, GDS310, GDL240, GDL280, GDL340, GDS090S, GDS180HT, GDL120, GDL210SHT),(lg) JNT carbon-fibre paper series (e.g. JNT15B, JNT17B, JNT18B, JNT20, JNT21 , JNT30),(lh) LINQCELL carbon-fibre paper (e.g. GDP180, GDP210, GDP210-MP, GDP- 210MPS, GDP 240, GDP340), and(11) Mitsubishi Chemicals PYROFIL™ GDL.

[0171] 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).

[0172] 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. GF051 BH, GF061 AH).

[0173] 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.

[0174] 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.

[0175] 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

[0176] 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.

[0177] 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.

[0178] 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)

[0179] The MPL is disposed on the GDL and may aid with electrical conductivity and / or water management.

[0180] 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).

[0181] 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% and95 wt%, between 75 wt% and 95 wt%, between 80 wt% and 95 wt%, between 85 wt% and95 wt%, between 90 wt% and 95 wt%, between 60 wt% and 90 wt%, between 60 wt% and85 wt%, between 60 wt% and 80 wt%, between 60 wt% and 75 wt%, between 60 wt% and70 wt%, between 60 wt% and 65 wt%, between 65 wt% and 90 wt%, between 70 wt% and85 wt%, or between 75 wt% and 80 wt% of carbon black.

[0182] 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% and30 wt%, between 5 wt% and 25 wt%, between 5 wt% and 20 wt%, between 5 wt% and15 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% and40 wt%, between 35 wt% and 40 wt%, between 10 wt% and 35 wt%, between 15 wt% and30 wt%, or between 20 wt% and 25 wt% of the hydrophobic polymer.

[0183] The MPL may have a thickness of between 10 pm and 100 pm, between 10 pm and 90 pm, between 10 pm and 80 pm, between 10 pm and 70 pm, between 10 pm and 60 pm, between 10 pm and 50 pm, between 10 pm and 40 pm, between 10 pm and 30 pm, between 10 pm and 20 pm, between 20 pm and 100 pm, between 30 pm and 100 pm, between 40 pm and 100 pm, between 50 pm and 100 pm, between 60 pm and 100 pm, between 70 pm and 100 pm, between 80 pm and 100 pm, between 90 pm and 100 pm,between 20 pm and 90 pm, between 30 pm and 80 pm, between 40 pm and 70 pm, or between 50 pm and 60 pm.

[0184] The MPL may have an average pore diameter of between 0 pm and 10 pm, between 0 pm and 9 pm, between 0 pm and 8 pm, between 0 pm and 7 pm, between 0 pm and 6 pm, between 0 pm and 5 pm, between 0 pm and 4 pm, between 0 pm and 3 pm, between 0 pm and 2 pm, between 0 pm and 1 pm, between 0 pm and 0.9 pm, between 0 pm and 0.8 pm, between 0 pm and 0.7 pm, between 0 pm and 0.6 pm, between 0 pm and 0.5 pm, between 0 pm and 0.4 pm, between 0 pm and 0.3 pm, between 0 pm and 0.2 pm, or between 0 pm and 0.1 pm.

[0185] 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)

[0186] 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.

[0187] 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.

[0188] The catalyst layer may have a thickness of between 1 pm and 100 pm, between 1 pm and 95 pm, between 1 pm and 90 pm, between 1 pm and 85 pm, between 1 pm and 80 pm, between 1 pm and 75 pm, between 1 pm and 70 pm, between 1 pm and 65 pm, between 1 pm and 60 pm, between 1 pm and 55 pm, between 1 pm and 50 pm,between 1 pm and 45 pm, between 1 pm and 40 pm, between 1 pm and 35 pm, between 1 pm and 30 pm, between 1 pm and 25 pm, between 1 pm and 20 pm, between 1 pm and 15 pm, between 1 pm and 10 pm, between 1 pm and 9 pm, between 1 pm and 8 pm, between 1 pm and 7 pm, between 1 pm and 6 pm, between 1 pm and 5 pm, between 1 pm and 4 pm, between 1 pm and 3 pm, or between 1 pm and 2 pm.

[0189] 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% to50%, between 30% to 55%, between 30% to 50%, between 30% to 45%, between 30% to40%, between 30% to 35%, between 35% to 75%, between 40% to 75%, between 45% to75%, between 50% to 75%, between 55% to 75%, between 60% to 75%, between 65% to75%, or between 70% to 75%.

[0190] The ionomencatalyst 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

[0191] The catalyst may include (6) a metal, (7) a non-metal, or a combination thereof.

[0192] The metal may be (6a) a transition metal, (6b) a post-transition metal, (6c) a metalloid, or a combination thereof, or an alloy thereof.

[0193] 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.

[0194] 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.

[0195] 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.

[0196] The catalyst including a non-metal may include (7a) carbon, (7b) a conductive polymer, or a combination thereof.

[0197] 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).

[0198] 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

[0199] 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).

[0200] 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.

[0201] Non-limiting examples of the anion exchange ionomer (AEI) include (8a) Fumion™ FAA-3 AEI, (8b) lonomr™ AEI (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) Pention™ AEI (e.g. D18, D35, D72), and (8f) PiperlON AEI.

[0202] 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.

[0203] 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), Fumion™ CEI (e.g. E-600, FSLA-102, FSLA-725), lonomr™ CEI (e.g. PP1 ), and Nation™ CEI (e.g. D520CS, D521CS, D2020CS, D2021CS).

[0204] 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% and25 wt%, between 5 wt% and 20 wt%, between 5 wt% and 15 wt%, between 5 wt% and10 wt%, between 10 wt% and 45 wt%, between 15 wt% and 45 wt%, between 20 wt% and45 wt%, between 25 wt% and 45 wt%, between 30 wt% and 45 wt%, between 35 wt% and45 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

[0205] 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.

[0206] 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.

[0207] 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:

[0208] 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 1-768 for these GDEs may further comprise an AEM asIdescribed herein, for example as shown in FIGs. 9(e)-(h). Further, in respect of GDE-1 , GDE- 2 and GDE-4 type GDEs as described herein, any of Embodiments 1-768 for these GDEs may further comprise an MPL as described herein, for example as shown in FIGs. 9(b), (d), (f) and (h), FIGs. 10(b) and (d), and FIGs. 12(b) and 12(d) . Further, in respect of GDE-1 , GDE-2, GDE-3, and GDE-4 type GDEs as described herein, any of Embodiments 1-768 for these GDEs may further comprise a mesh as described herein, for example as shown in FIGs. 9(c)-(h), 10(c)-(d), 11 (b) and 12(c) and 12(d).

[0209] 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 1-768 at least one of the 1stGDL and the 2ndGDL is the GDL as defined for the respective embodiment of Embodiments 1-768. 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 1-768. 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 1-768. 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 1-768. 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 1-768.

[0210] 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.

[0211] 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.I

[0212] In an embodiment, the AEM of the GDE is a Fumasep™, a Neosepta™, an Orion™, a Xergy Xion Pention™, a PiperlON™, a Ralex™, a Sustanion™, or an lonomr™ anion exchange membrane.

[0213] As mentioned, in an embodiment the electrochemical cell is one that comprises a GDE. The GDE may be any of those as described herein. In the electrochemical cells herein, one or more ion exchange membranes are stacked in an order specific to the components of the salt solution or salt solution concentrate 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.

[0214] Various different types of multi-compartment electrochemical cells comprising GDEs may be used, such as those described herein.5-compartment membrane electrolysis cell

[0215] In an embodiment, the membrane electrolysis cell comprises five compartments as depicted in FIG. 13. 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.

[0216] An anode is housed in the anode compartment.

[0217] 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. 9(a)-(d) is in direct contact with the 1stAEM shown in FIG. 13.IOtherwise, the AEM of the GDEs shown in FIGs. 9(e)-(h) is the 1stAEM shown in FIG. 13. 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 1stGEM.• When the GDE is GDE-2 described herein, the COM of the GDEs shown in FIGs. 10(a)-(d) is in place of the 1stAEM shown in FIG. 13. The COM 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 COM. The base build-up compartment is defined by the COM and the 1stGEM.• When the GDE is GDE-3 described herein, the 1stAEM shown in FIG. 13 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. 12(a)-(d) is the 1stAEM shown in FIG. 13. 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 1stGEM.

[0218] The 1stGEM 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 1stGEM. The salt depletion compartment is defined by the 1stGEM 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 buildup compartment is defined by the 2ndAEM and a 2ndGEM. The 2ndGEM defines a boundary lbetween 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.

[0219] The 1stand 2ndAEMs are as described herein and may be the same or different. The 1stand 2ndOEMs are as described herein and may be the same or different.

[0220] 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. 13, the negative ions from the salt solution migrate towards the positively charged anode compartment through the 2ndAEM and remain in the acid buildup 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 buildup compartment. The protons combine with the negative ions to form an acid.

[0221] If the salt solution comprises LiCI, Li2SO4, Li3PO4, UNO3, or Lil, then LiOH will be produced in the base build-up compartment and HCI, H2SO4, H3PO4, HNO3, HI, respectively, will be produced simultaneously in the acid build-up compartment. Likewise, if the salt solution comprises NaCI, Na2SO4, Na3PO4, NaNOs, or Nal, then NaOH will be produced in the base build-up compartment and HCI, H2SO4, H3PO4, HNO3, HI, respectively, will be produced simultaneously in the acid build-up compartment. And, if the salt solution comprises KCI, K2SO4, K3PO4, KNO3, or KI, then KOH will be produced in the base build-up compartment and HCI, H2SO4, H3PO4, HNO3, HI, respectively, will be produced simultaneously in the acid build-up compartment.I4-compartment membrane electrolysis cell

[0222] In an embodiment, the membrane electrolysis cell comprises four compartments as depicted in FIG. 14. 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.

[0223] An anode is housed in the anode compartment.

[0224] 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. 9(a)-(d) is in direct contact with a 1stAEM shown in FIG. 14. Otherwise, the AEM of the GDEs shown in FIGs. 9(e)-(h) is the 1stAEM shown in FIG. 14. 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. 10(a)-(d) is in place of the 1stAEM shown in FIG. 14. The CCM defines a boundary between the cathode compartment and the base buildup 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 1stAEM shown in FIG. 14 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.I• When the GDE is GDE-4 described herein, the AEM of the GDEs shown in FIGs. 12(a)-(d) is the 1stAEM shown in FIG. 14. 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 GEM.

[0225] The GEM 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 GEM. The salt depletion compartment is defined by the GEM 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.

[0226] The 1stand 2ndAEMs are as described herein and may be the same or different. The GEM is as described herein.

[0227] 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 GEM 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 GEM. Therefore, a base is formed in the base build-up compartment. As shown in FIG. 14, the negative ions from the salt solution migrate towards the positively charged anode compartment through the 2ndAEM into the anode compartment.

[0228] If the salt solution comprises (a) LiCI, LiBr, or Lil, (b) NaCI, NaBr, or Nal, or (c) KCI, KBr, or KI, then (a) LiOH, (b) NaOH, or (c) KOH, respectively, will be produced in the base build-up compartment. Simultaneously, HCI, HBr or HI will be produced in the anode lcompartment (dependent of the input salt solution) with the possibility of production of CI2, Br2 or I2, respectively.

[0229] If the salt solution comprises Li2SO4, Li3PO4, or IJNO3, 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 NaNOs, 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.3-compartment membrane electrolysis cell

[0230] In an embodiment, the membrane electrolysis cell comprises three compartments as depicted in FIG. 15. The membrane electrolysis cell comprises a base build-up compartment interposed between a cathode compartment and an anode compartment.

[0231] An anode is housed in the anode compartment.

[0232] 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. 9(a)-(d) is in direct contact with an AEM shown in FIG. 15. Otherwise, the AEM of the GDEs shown in FIGs. 9(e)-(h) is the AEM shown in FIG. 15. 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. 10(a)-(d) is in place of the AEM shown in FIG. 15. The CCM defines a boundary between the cathode compartment and the base build- lup 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. 15 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. 12(a)-(d) is the AEM shown in FIG. 15. 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.

[0233] 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.

[0234] The CEM and AEM are as described herein.

[0235] 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 through the 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.I

[0236] If the salt solution comprises (a) LiCI, LiBr, or Lil, (b) NaCI, NaBr, or Nal, or (c) KCI, KBr, or KI, then (a) LiOH, (b) NaOH, or (c) KOH, respectively, will be produced in the base build-up compartment. Simultaneously, HOI, HBr or HI will be produced in the anode compartment (dependent of the input salt solution) with the possibility of production of CI2, Br2 or I2, respectively.

[0237] 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, Na3O4, 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, K3O4, or KNO3, then KOH will be produced in the base build-up compartment and H2SO4, H3O4, or HNO3, respectively, will be produced simultaneously in the anode compartment.2-compartment membrane electrolysis cell

[0238] In an embodiment, the membrane electrolysis cell comprises two compartments as depicted in FIG. 16. The membrane electrolysis cell comprises a cathode compartment and an anode compartment. The cathode and anode compartments are in fluid communication via a OEM. The OEM is as described herein.

[0239] An anode is housed in the anode compartment.

[0240] A cathode comprising a GDE as shown in FIGs. 9(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 GEM and the CL of the GDE.

[0241] 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.

[0242] If the salt solution comprises (a) LiCI, LiBr, or Lil, (b) NaCI, NaBr, or Nal, or (c) KCI, KBr, or KI, then (a) LiOH, (b) NaOH, or (c) KOH, respectively, will be produced in thecathode compartment. Simultaneously, HCI, HBr or HI will be produced in the anode compartment (dependent of the input salt solution) with the possibility of production of CI2, Br2 or I2, respectively.

[0243] 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 anode compartment. 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.Anion Exchange Membranes (AEM)

[0244] An 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.

[0245] 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.

[0246] 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.

[0247] Non-limiting examples of the anion exchange membrane include:(10a) Fumasep™ FAA 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),(10b) Fumasep™ FAB AEMs (e.g. FAB-PK-75, FAB-PK-130),(10c) Fumasep™ FAD AEMs (e.g. FAD-55, FAD-PET-75),(10d) Fumasep™ FAM AEMs (e.g. FAM),(10e) Fumasep™ FAAM AEMs (e.g. FAAM-10, FAAM-15, FAAM-20, FAAM-40),(1 Of) Fumasep™ FAP AEMs (e.g. FAP-330, FAP-450, FAP-330-PE, FAP-330-PE, FAP-420-PE),(10g) Fumasep™ FAPQ AEMs (e.g. FAPQ-330, FAPQ-375-PP),(1 Oh) Fumasep™ FAS AEMs (e.g. FAS-50, FAS-30, FAS-PET-75, FAS-PE-130),(10i) Neosepta™ AEMs (e.g. ACN, ACS, AFN, AFX, AHA, AMX, ASE, AXP-D),(10j) ORION™ AEMs (e.g. TM1),(10k) Xergy Xion™ Pention™ AEMs (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),(101) PiperlON™ AEMs (e.g. PiperlON Anion Exchange Membrane - 15 microns, PiperlON Anion Exchange Membrane - 20 microns, PiperlON Anion Exchange Membrane - 40 microns, PiperlON Anion Exchange Membrane - 60 microns, PiperlON Anion Exchange Membrane - 80 microns),(10m) RALEX™ AEMs (e.g. AMHPES, AMHPP),(10n) SELEMION™ AEMs (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) lonomr AEMs (e.g. Aemion).Cation Exchange Membranes (CEM)

[0248] A 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.

[0249] 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.

[0250] 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.

[0251] Non-limiting examples of the anionic functional group include a sulfonate such as a perfluorosulfonate; a carboxylate; a phosphonate; and a phenolate anion.

[0252] Non-limiting examples of the cation exchange membrane include:(l la) Aquivion® CEMs (e.g. E87-05S, E98-05S, E98-09S, E98-15S),(l l b) Fumasep™ CEMs (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-PK-75, FKE-50, FKL-PK-130, FKM, FKS-30, FKS-50, FKS-PET-75, FKS-PET-130),(l lc) Fumapem™ CEMs (e.g. F-14100, F-930, F-930-RFS, FS-715-RFS, FS-930, FS-930-RFS, F-950),(l ld) Nation™ CEMs (e.g. N115, N117, N324, N417, N424, N438, N551 , N1110),(l le) Neosepta™ CEMs (e.g. CMB, CMX, CSE, CXP-S),(l lf) SELEMION™ CEMs (e.g. CMD, CMF, CMTE, CMV, CMVN, CSC), and(11g) Exergy Xion™ GEMS (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),(11 h) lonomr™ OEMs (e.g. Permion).

[0253] Various particular embodiments of the electrochemical cells of the present disclosure include membrane electrolysis cells (MEG), each as defined in the following rows, wherein each entry is a group number as defined above:2-compartment membrane electrolysis cell3-compartment membrane electrolysis cell-compartment membrane electrolysis cell-compartment membrane electrolysis cell

[0254] The flow rate of the salt solution or salt solution concentrate in any of the electrochemical 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, between 0.5 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.

[0255] The flow rate of the gas comprising oxygen in the electrochemical 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, between5 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 and25 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.

[0256] The temperature of the salt solution or the salt solution concentrate in the electrochemical cells described herein may be between 40 and 70°C, between 40 and 65°C, between 40 and 60°C, between 40 and 55°C, between 40 and 50°C, between 40 and 45°C, between 45 and 70°C, between 50 and 70°C, between 55 and 70°C, between 60 and 70°C, between 65 and 70°C, between 45 and 65°C, or between 50 and 60°C.

[0257] Exemplary Embodiments

[0258] (1) A process for producing an alkali metal compound comprising: receiving a salt solution in a solar-powered steam generator to produce steam and a salt solution concentrate; delivering the salt solution concentrate to an electrochemical cell; generating electrical power by directing at least a portion of the steam to a turbine coupled to a generator; and powering the electrochemical cell with the electrical power to produce a product solution comprising the alkali metal compound from the salt solution concentrate.

[0259] (2) The process of (1), further comprising producing a condensate from the step of generating electrical power.

[0260] (3) The process of (2), wherein the condensate is used for water consumption in the electrochemical cell, recycled to an underground reservoir, or a combination thereof.

[0261] (4) The process of any one of (1) to (3), wherein the solar-powered steam generator is powered by a solar parabolic trough, a solar dish, a solar power tower, a linear Fresnel reflector, or any combination thereof.

[0262] (5) The process of any one of (1 ) to (4), wherein the salt solution concentrate is pre-treated before being delivered to the electrochemical cell.

[0263] (6) The process of (5), wherein the salt solution concentrate is pre-treated to remove divalent cations.

[0264] (7) The process of (5), wherein the salt solution concentrate is pre-treated to remove boron.

[0265] (8) The process of any one of (1 ) to (7), wherein the alkali metal compound comprises LiOH, NaOH, KOH, or any combination thereof.

[0266] (9) The process of one of (1 ) to (8), wherein the salt solution comprisesLiCI, Li2SO4, Li3PO4, LiNO3, Lil, LiBr, NaCI, Na2SO4, Na3PO4, NaNO3, Nal, NBr, KOI, K2SO4, K3PO4, KNO3, KI, KBr, or any combination thereof.

[0267] (10) The process of any one of (1 ) to (9), further comprising crystallizing the alkali metal compound from the product solution.

[0268] (11 ) The process of any one of (1 ) to (10), wherein the salt solution is an aqueous brine obtained from an underground deposit or reservoir.

[0269] (12) The process of any one of (1) to (1 1 ), wherein the electrochemical cell is the electrochemical cell as described herein.

[0270] (13) A system comprising: a solar-powered steam generator; an electrochemical cell fluidly coupled to the solar-powered steam generator; a turbine fluidly coupled to the solar-powered steam generator; and a generator coupled to the turbine to generate electrical power.

[0271] (14) The system of (13), wherein the solar-powered steam generator is configured to receive a salt solution.

[0272] (15) The system of (14), wherein the salt solution is an aqueous brine obtained from an underground deposit or reservoir.

[0273] (16) The system of (13) or (14), wherein the salt solution comprises LiCI, Li2SO4, Li L2Si3OPO4 4, LiNO3, Lil, LiBr, NaCI, Na2SO4, Na3PO4, NaNO3, Nal, NBr, KCI, K2SO4, K3PO4, KNO3, KI, KBr, or any combination thereof.

[0274] (17) The system of any one of (13) to (16), wherein the electrochemical cell is configured to receive a salt solution concentrate from the solar-powered steam generator.

[0275] (18) The system of (17), which further comprises one or more pre-treatment components for pre-treating the salt solution concentrate prior to the salt solution concentrate being received by the electrochemical cell.

[0276] (19) The system of (18), wherein the one or more pre-treatment components are configured to remove divalent cations, boron, or a combination thereof from the salt solution concentrate.

[0277] (20) The system of any one of (1) to (19), wherein the electrochemical cell is the electrochemical cell as described herein.

[0278] (21 ) The system of any one of (1) to (20), further comprises a cooling device for converting at least a portion of the steam formed by the solar-powered steam generator into a condensate.

[0279] (22) The system of (21), which is configured to deliver the condensate to the electrochemical cell, an underground reservoir, or a combination thereof.

[0280] (23) The system of any one of (13) to (22), wherein the solar-powered steam generator comprises and / or is powered by a solar parabolic trough, a solar dish, a solar power tower, a linear Fresnel reflector, or any combination thereof.

[0281] (24) The system of any one of (13) to (23), wherein the electrochemical cell produces a product solution comprising an alkali metal compound.

[0282] (25) The system of (24), wherein the alkali metal compound is LiOH, NaOH,KOH, or any combination thereof.

[0283] (26) The system of (24) or (25), further comprising a crystallization unit for crystallizing the alkali metal compound from the product solution.

[0284] (27) A process for producing an alkali metal compound comprising: receiving a salt solution in an electrochemical cell comprising a cathode and an anode; applying an electrical potential between the cathode and anode; producing hydrogen gas at the cathode; producing from the electrochemical cell a product solution comprising the alkali metal compound; and delivering the hydrogen gas to a hydrogen fuel cell to generate electrical power.

[0285] (28) The process of (27), wherein the electrical power is used to power the electrochemical cell.

[0286] (29) The process of (27) or (28), further comprising producing water from the hydrogen fuel cell.

[0287] (30) The process of (29), wherein the water is used for water consumption in the electrochemical cell, recycled to an underground reservoir, or a combination thereof.

[0288] (31 ) The process of any one of (27) to (30), wherein the alkali metal compound comprises LiOH, NaOH, KOH, or any combination thereof.

[0289] (32) The process of any one of (27) to (31 ), wherein the salt solution is an aqueous brine obtained from an underground deposit or reservoir.

[0290] (33) The process of any one of (27) to (32), wherein the salt solution comprises LiCI, Li2SO4, Li3PO4, LiNO3, Lil, LiBr, NaCI, Na2SO4, Na3PO4, NaNC3, Nal, NBr, KCI, K2SO4, K3PO4, KNO3, KI, KBr, or any combination thereof.

[0291] (34) The process of any one of (27) to (33), wherein the electrochemical cell is the electrochemical cell as described herein.

[0292] (35) A process for producing an alkali metal compound comprising: receiving a salt solution in a solar-powered steam generator to produce steam and a salt solution concentrate; producing a condensate from the steam and delivering the condensate to an electrochemical cell, an underground reservoir, or a combination thereof; delivering the salt solution concentrate to the electrochemical cell to produce a product solution comprising the alkali metal compound from the salt solution concentrate.

[0293] 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.

[0294] 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.

[0295] 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.

[0296] 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.

[0297] 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 dis-cussed, 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.

[0298] 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 process for producing an alkali metal compound comprising:- receiving a salt solution in a solar-powered steam generator to produce steam and a salt solution concentrate;- delivering the salt solution concentrate to an electrochemical cell;- generating electrical power by directing at least a portion of the steam to a turbine coupled to a generator; and- powering the electrochemical cell with the electrical power to produce a product solution comprising the alkali metal compound from the salt solution concentrate.

2. The process of claim 1 , wherein the solar-powered steam generator is powered by a solar parabolic trough, a solar dish, a solar power tower, a linear Fresnel reflector, or any combination thereof.

3. The process of claim 1 or 2, wherein the salt solution concentrate is pre-treated before being delivered to the electrochemical cell.

4. The process of any one of claims 1 to 3, wherein the alkali metal compound comprises LiOH, NaOH, KOH, or any combination thereof.

5. The process of one of claims 1 to 4, wherein the salt solution comprises LiCI, Li2SO4, Li3PO4, LiNO3, Lil, LiBr, NaCI, Na2SO4, Na3PO4, NaNO3, Nal, NBr, KOI, K2SO4, K3PO4, KNO3, KI, KBr, or any combination thereof.

6. A system comprising:- a solar-powered steam generator;- an electrochemical cell fluidly coupled to the solar-powered steam generator;- a turbine fluidly coupled to the solar-powered steam generator; and- a generator coupled to the turbine to generate electrical power.

7. The system of claim 6, wherein the solar-powered steam generator is configured to receive a salt solution.

8. The system of claim 6 or 7, wherein the salt solution comprises LiCI, Li2SO4, Li3PO4, LiNO3, Lil, LiBr, NaCI, Na2SO4, Na3PO4, NaNO3, Nal, NBr, KCI, K2SO4, K3PO4, KNO3, KI, KBr, or any combination thereof.

9. The system of any one of claims 6 to 8, wherein the electrochemical cell is configured to receive a salt solution concentrate from the solar-powered steam generator.

10. The system of claim 9, which further comprises one or more pre-treatment components for pre-treating the salt solution concentrate prior to the salt solution concentrate being received by the electrochemical cell.1 1. The system of any one of claims 1 to 10, further comprises a cooling device for converting at least a portion of the steam formed by the solar-powered steam generator into a condensate.

12. The system of any one of claims 6 to 11 , wherein the solar-powered steam generator comprises and / or is powered by a solar parabolic trough, a solar dish, a solar power tower, a linear Fresnel reflector, or any combination thereof.

13. The system of any one of claims 6 to 12, wherein the electrochemical cell produces a product solution comprising an alkali metal compound.

14. The system of claim 13, wherein the alkali metal compound is LiOH, NaOH, KOH, or any combination thereof.

15. The system of claim 13 or 14, further comprising a crystallization unit for crystallizing the alkali metal compound from the product solution.

16. A process for producing an alkali metal compound comprising:- receiving a salt solution in an electrochemical cell comprising a cathode and an anode;- applying an electrical potential between the cathode and anode;- producing hydrogen gas at the cathode;- producing from the electrochemical cell a product solution comprising the alkali metal compound; and - delivering the hydrogen gas to a hydrogen fuel cell to generate electrical power.

17. The process of claim 16, wherein the electrical power is used to power the electrochemical cell.

18. The process of claim 16 or 17, wherein the alkali metal compound comprises LiOH, NaOH, KOH, or any combination thereof.

19. The process of any one of claims 16 to 18, wherein the salt solution comprises LiCI, Li2SO4, Li3PO4, LiNO3, Lil, LiBr, NaCI, Na2SO4, Na3PO4, NaNO3, Nal, NBr, KOI, K2SO4, K3PO4, KNO3, KI, KBr, or any combination thereof.

20. A process for producing an alkali metal compound comprising:- receiving a salt solution in a solar-powered steam generator to produce steam and a salt solution concentrate;- producing a condensate from the steam and delivering the condensate to an electrochemical cell, an underground reservoir, or a combination thereof;- delivering the salt solution concentrate to the electrochemical cell to produce a product solution comprising the alkali metal compound from the salt solution concentrate.

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