Method and apparatus for electrolyzing lithium brine

Abstract

This disclosure relates to methods and apparatus for producing lithium hydroxide using electrolysis.

Description

Technical Field

[0001] This disclosure relates to methods and apparatus for producing lithium hydroxide using electrolysis. Background Technology

[0002] Demand for lithium hydroxide is growing rapidly. The market for lithium hydroxide is expanding, and current global production capacity may not be able to meet the anticipated increase in demand. For example, lithium hydroxide is used as a carbon dioxide absorbent in gas and air purification, as a heat transfer medium, as a battery electrolyte, as a polymerization catalyst, in ceramics, in Portland cement formulations, in the manufacture of other lithium compounds, and in esterification, particularly in the manufacture of lithium stearate.

[0003] Lithium-ion batteries have become the preferred battery for several existing and emerging applications due to their high energy density to weight ratio and relatively long lifespan compared to other battery types. Lithium-ion batteries are used in applications such as laptops, mobile phones, medical devices, and implants (e.g., pacemakers). They are also used in automobiles (e.g., hybrid and electric vehicles), which are environmentally friendly due to reduced emissions and less reliance on hydrocarbon fuels.

[0004] High-purity lithium hydroxide can be prepared from an aqueous lithium salt solution (lithium brine) by electrolysis of the lithium brine in a membrane cell comprising an ion-selective membrane (cation exchange membrane) that allows lithium cations to permeate but prevents anions from diffusing through.

[0005] WO 2023 / 281 033 A1 discloses the electrolysis of an aqueous solution containing lithium sulfate in a low pH range. It also discloses a method for obtaining an aqueous solution containing lithium by stripping a lithium-containing liquid medium with an acidic aqueous solution, and for electrolyzing the lithium-containing aqueous solution. Further disclosure includes a method for preparing the lithium-containing liquid medium.

[0006] WO 2015 / 058 287 A1 provides a method comprising electrolyzing or electrodialyzing an aqueous composition comprising lithium sulfate and / or lithium bisulfate to convert at least a portion of the sulfate into lithium hydroxide. During electrolysis or electrodialysis, the aqueous composition is maintained at least substantially at a pH having a value of about 1 to about 4; and the lithium hydroxide is converted into lithium carbonate. Alternatively, the lithium sulfate and / or lithium bisulfate may be subjected to a first electromembrane process comprising a two-chamber membrane process to convert the lithium sulfate and / or lithium bisulfate into lithium hydroxide, and to obtain a first lithium-reduced aqueous stream and a first lithium hydroxide-rich aqueous stream; and the first lithium-reduced aqueous stream may be subjected to a second electromembrane process comprising a three-chamber membrane process to prepare at least another portion of the lithium hydroxide, and to obtain a second lithium-reduced aqueous stream and a second lithium hydroxide-rich aqueous stream.

[0007] WO 2013 / 159 194 A1 discloses methods for preparing lithium hydroxide, which include electrolyzing an aqueous composition containing lithium sulfate under conditions suitable for converting at least a portion of the lithium sulfate into lithium hydroxide, wherein the aqueous composition containing lithium sulfate has a pH greater than 7 during said electrolysis.

[0008] WO 2010 / 056 322 A1 discloses a method for recovering lithium in the form of lithium hydroxide, wherein an aqueous stream containing lithium ions is fed into a bipolar electrodialysis cell, wherein the cell forms a lithium hydroxide solution.

[0009] US 2019 / 032227 A1 discloses a method for producing lithium hydroxide that integrates a lithium stripping stage with a lithium hydroxide production process carried out in a two-chamber electrolytic cell. The method includes: (a) providing a two-chamber electrolytic cell having an anode, a cathode, and a membrane barrier disposed therebetween, said membrane barrier being lithium (Li₂O₃). + ) cations and protons (H + (a) Permeable; (b) Stripping the lithium-loaded medium using an aqueous stripping solution to extract the lithium cations from the medium into the aqueous stripping solution, producing a lithium-containing aqueous intermediate solution and the stripped medium; (c) Introducing the lithium-containing aqueous intermediate solution into the anode chamber of the two-chamber electrolytic cell to form an anolyte; (d) Introducing the aqueous medium into the cathode chamber of the two-chamber electrolytic cell to form a cathode electrolyte; (e) Operating the cell so that: (i) oxygen is generated at the anode; (ii) protons (H+) are generated in the anolyte. + (iii) generating hydrogen gas and hydroxide ions (OH-) at the cathode. - (f) and causing a portion of the lithium cations and a portion of the protons to pass through the membrane barrier, wherein the protons react with the hydroxide ions to produce water in the cathode electrolyte; (g) removing an aqueous product stream from the cathode chamber, the product stream containing dissolved lithium hydroxide; and (g) recirculating an outflow containing the anolyte from the anode chamber for the stripping of the lithium-loaded medium.

[0010] Typical membranes used in electrolysis are polymeric materials containing perfluorinated and polyfluorinated alkyl substances (PFAS), such as sulfonated tetrafluoroethylene-based fluoropolymers-polymers (e.g., Nafion). TMDuring the electrolysis process, depending on the amount of impurities in the brine solution used, other metal hydroxides and / or metal carbonates may form. These metal hydroxides and carbonates may deposit within the cation exchange membrane, spanning a pH range of 0 to 14. Replacing cation exchange membranes is expensive and time-consuming. To reduce operating costs, frequent membrane replacements should be avoided, and membrane materials should be readily available and cost-effective. Summary of the Invention

[0011] This invention utilizes spent PFAS membranes from an electrochemical cell for the electrolysis of lithium sulfate solution. Spent membranes can be widely obtained from various industrial electrolysis processes, such as the electrolysis of sodium chloride aqueous solutions. The spent membranes can be used without any modification. In some embodiments, spacers are used in the electrochemical cell for lithium sulfate electrolysis, which helps extend the lifespan of the cation exchange membrane. The spent membranes are fully hydrated, while the swelling process of virgin membranes typically takes some time, and the electrolyzer requires a longer time to reach full operation. Attached Figure Description

[0012] Figure 1 An exemplary electrolytic cell is shown in this disclosure.

[0013] Figure 2 A graph showing electrode temperature versus time during long-term test runs of the methods and apparatus disclosed herein is presented.

[0014] Figure 3 A graph showing the pool voltage versus time during long-term test operation of the methods and apparatus disclosed herein is presented. Detailed Implementation

[0015] This disclosure provides a method for electrolyzing lithium-containing brine, such as an aqueous solution of lithium sulfate, in an electrochemical cell including at least one cation exchange membrane, wherein the at least one cation exchange membrane is a waste PFAS membrane.

[0016] The methods disclosed herein include i) operating a sulfonated cation exchange membrane containing perfluoroalkyl and polyfluoroalkyl substances (PFAS) for a period of time ranging from 7,500 hours to 30,000 hours in an industrial electrolysis process other than lithium brine electrolysis to obtain a spent PFAS membrane, and electrolyzing lithium brine in an electrochemical cell comprising at least one cation exchange membrane, wherein the at least one cation exchange membrane is a spent PFAS membrane.

[0017] As used herein, the term “electrolysis” refers to the chemical decomposition that occurs by passing an electric current through a liquid or solution containing ions.

[0018] As used herein, the term “about” means ± 5% of the stated number. Unless otherwise stated, all numbers are assumed to be modified by “about”.

[0019] In the context of this disclosure, “waste PFAS membrane” is a cation exchange polymer membrane that has been operated in another industrial electrolysis process (e.g., electrolysis of aqueous sodium chloride or aqueous hydrogen chloride solution) for a period of time ranging from 7,500 hours to 30,000 hours, such as from 17,000 hours to 25,000 hours.

[0020] PFAS membranes are sulfonated membranes comprising perfluoroalkyl and polyfluoroalkyl substances (PFAS). In some embodiments, the sulfonated membrane has a hydrocarbon backbone or a PTFE backbone. In some embodiments, the sulfonated membrane is made of a sulfonated tetrafluoroethylene-based fluoropolymer copolymer. In some embodiments, the sulfonated membrane is made of sulfonated polyarylene ethers or polyphenylene sulfones, such as polyarylene ether Ultrason. ® or polyphenylsulfone Ultrason ® In some embodiments, the polymer membrane is selected from at least one of the following: perfluorinated cation exchange membranes, PEEK-reinforced cation exchange membranes, PTFE-reinforced cation exchange membranes, and combinations thereof. In some embodiments, the membrane is made of a fluorinated copolymer having sulfonic acid groups. In some embodiments, the membrane is a perfluorosulfonic acid polymer membrane. In some embodiments, the perfluorosulfonic acid polymer membrane is made of tetrafluoroethylene-perfluoro-3,6-dioxa-4-methyl-7-octene sulfonic acid copolymer (NAFION from DuPont). TM Made from ( ).

[0021] Waste membranes can be widely obtained from various industrial electrolysis processes, such as the electrolysis of aqueous sodium chloride or hydrogen chloride solutions. Waste membranes can be used without any modification. They are already fully hydrated, whereas the swelling process of virgin membranes typically takes some time, and the electrolyzer requires even longer to reach full operation.

[0022] In some embodiments, the waste PFAS membrane (EOL PFAS membrane) has a thickness in the range of 380 µm to 420 µm, for example 390 µm to 410 µm, for example 395 µm to 405 µm.

[0023] In some embodiments, the thickness of the EOL PFAS membrane is in the range of 1.1 to 1.2 times, for example 1.1 to 1.15 times, the thickness of the corresponding original PFAS membrane (i.e., the membrane before operation in the industrial electrolysis process).

[0024] Lithium-containing brine is an aqueous solution containing lithium. The electrochemical decomposition of water produces hydrogen gas on the cathode side and oxygen gas on the anode side. The cathode and anode of the electrolytic cell are separated by a cation exchange membrane. Under alkaline or pH-neutral conditions, hydrogen ions and hydroxide ions are generated at the cathode. Protons are formed during oxygen formation at the anode side. During brine electrolysis, lithium ions migrate from the anolyte to the catholyte through the cation exchange membrane.

[0025] In some embodiments, the aqueous solution containing lithium has a lithium concentration ranging from about 5 g / L to about 100 g / L. In some embodiments, the aqueous solution containing lithium has a lithium concentration ranging from about 20 g / L to about 100 g / L. In some embodiments, the aqueous solution containing lithium has a lithium concentration ranging from about 30 g / L to about 100 g / L. In some embodiments, the aqueous solution containing lithium has a lithium concentration ranging from about 40 g / L to about 100 g / L. In some embodiments, the aqueous solution containing lithium has a lithium concentration ranging from about 50 g / L to about 100 g / L. In some embodiments, the aqueous solution containing lithium has a lithium concentration ranging from about 60 g / L to about 100 g / L. In some embodiments, the aqueous solution containing lithium has a lithium concentration ranging from about 70 g / L to about 100 g / L. In some embodiments, the aqueous solution containing lithium has a lithium concentration ranging from about 80 g / L to about 100 g / L. In some embodiments, the aqueous solution containing lithium has a lithium concentration ranging from about 90 g / L to about 100 g / L. In some embodiments, the aqueous solution containing lithium has a lithium concentration ranging from about 20 g / L to about 90 g / L. In some embodiments, the aqueous solution containing lithium has a lithium concentration ranging from about 20 g / L to about 80 g / L. In some embodiments, the aqueous solution containing lithium has a lithium concentration ranging from about 20 g / L to about 70 g / L. In some embodiments, the aqueous solution containing lithium has a lithium concentration ranging from about 20 g / L to about 60 g / L. In some embodiments, the aqueous solution containing lithium has a lithium concentration ranging from about 20 g / L to about 50 g / L. In some embodiments, the aqueous solution containing lithium has a lithium concentration ranging from about 20 g / L to about 40 g / L. In some embodiments, the aqueous solution containing lithium has a lithium concentration ranging from about 20 g / L to about 30 g / L. In some embodiments, the aqueous solution containing lithium has a lithium concentration ranging from about 30 g / L to about 90 g / L. In some embodiments, the aqueous solution containing lithium has a lithium concentration ranging from about 40 g / L to about 80 g / L. In some embodiments, the aqueous solution containing lithium has a lithium concentration ranging from about 50 g / L to about 70 g / L.

[0026] Those skilled in the art will understand that various reaction parameters will vary depending on many factors, such as the nature of the starting materials, their purity level, the scale of the reaction, and all parameters (as they can be interdependent), and that reaction conditions can be adjusted accordingly to optimize the yield.

[0027] In some embodiments, the method is used in the range of 0.05 A / cm. 2 Up to 2.0 A / cm 2 For example, 0.1 A / cm 2 Up to 1A / cm 2 For example, 0.3 A / cm 2 Up to 1 A / cm 2 Or 0.4 A / cm 2 Up to 0.9 A / cm 2 The current density.

[0028] In some embodiments, the method uses a voltage ranging from 0 V to 10 V, for example 0 V to 8 V, for example 3 V to 7 V, or 5.5 V to 6.5 V.

[0029] In some embodiments of the method, the aqueous solution containing lithium has a temperature ranging from 20°C to 95°C, for example 30°C to 90°C, for example 40°C to 85°C, or 40°C to 60°C.

[0030] According to one aspect, this disclosure provides a method for preparing lithium hydroxide, the method comprising electrolyzing an aqueous composition containing a lithium compound under conditions suitable for converting at least a portion of the lithium compound into lithium hydroxide.

[0031] In some embodiments of the method, the pH of the aqueous composition containing lithium compounds is in the range of 2 to 12.

[0032] In some embodiments, the method includes electrolyzing an aqueous composition containing lithium sulfate under conditions suitable for converting at least a portion of the lithium sulfate into lithium hydroxide, wherein during electrolysis, the anolyte has a pH of less than 7 and the catholyte has a pH of greater than 7.

[0033] In some embodiments, the method includes electrolyzing an aqueous composition containing lithium sulfate under conditions suitable for converting at least a portion of the lithium sulfate into lithium hydroxide, wherein during electrolysis, the anolyte has a pH in the range of 0 to 7 and the catholyte has a pH in the range of 7 to 15.

[0034] According to another aspect, a method for preparing lithium hydroxide is provided, the method comprising leaching an acid-calcined lithium-containing material with water to obtain a lithium-containing material. +An aqueous composition containing at least one metal ion; making Li + An aqueous composition containing at least one metal ion is reacted with an alkali to obtain a pH of about 4.5 to about 6.5, thereby causing at least one metal ion to precipitate at least partially in the form of at least one hydroxide, in order to obtain a precipitate containing at least one hydroxide and containing Li. + An aqueous composition having a reduced content of at least one metal ion, and separating the aqueous composition from the precipitate; making the Li-containing... + An aqueous composition having a reduced content of at least one metal ion is contacted with an ion exchange resin to at least partially remove at least one metal ion from the composition, thereby obtaining an aqueous composition containing a lithium compound; and the aqueous composition containing the lithium compound is electrolyzed under conditions suitable for converting at least a portion of the lithium compound into lithium hydroxide.

[0035] According to another aspect, a method for preparing lithium hydroxide is provided, the method comprising leaching a lithium-containing material that has been alkali-calcined with water to obtain a lithium-containing material. + An aqueous composition containing at least one metal ion; making Li + An aqueous composition containing at least one metal ion is reacted with an alkali to obtain a pH of about 4.5 to about 6.5, thereby causing at least one metal ion to precipitate at least partially in the form of at least one hydroxide, in order to obtain a precipitate containing at least one hydroxide and containing Li. + An aqueous composition having a reduced content of at least one metal ion, and separating the aqueous composition from the precipitate; optionally, containing Li + The aqueous composition, having a reduced content of at least one metal ion, reacts with another alkali to obtain a pH of about 9.5 to about 11.5, and optionally reacts with at least one metal carbonate, thereby causing at least one metal ion to optionally precipitate at least partially in the form of at least one carbonate, to obtain a precipitate optionally containing at least one carbonate and containing Li. + Furthermore, it comprises an aqueous composition with reduced content of at least one metal ion, and separates the aqueous composition from the precipitate; thereby containing Li + An aqueous composition having a reduced content of at least one metal ion is contacted with an ion exchange resin to at least partially remove at least one metal ion from the composition, thereby obtaining an aqueous composition containing a lithium compound; and the aqueous composition containing the lithium compound is electrolyzed under conditions suitable for converting at least a portion of the lithium compound into lithium hydroxide.

[0036] The method disclosed herein can be effective for processing a variety of lithium-containing materials. Lithium-containing materials can be lithium-containing ores, lithium compounds, or recycled industrial lithium-containing entities. For example, lithium-containing ores can be, for instance, α-spodumene, β-spodumene, lepidolite, pegmatite, petalite, nepheline, lithium phosphate, lithium montmorillonite, montmorillonite, clay, or mixtures thereof. Lithium compounds can be, for example, LiCl, Li₂SO₄, LiHCO₃, Li₂CO₃, LiNO₃, LiC₂H₃O₂ (lithium acetate), LiF, lithium stearate, or lithium citrate. Lithium-containing materials can also be recycled industrial lithium-containing entities, such as lithium-ion batteries, other lithium products, or derivatives thereof.

[0037] In some embodiments, the aqueous solution containing lithium is obtained by leaching lithium-containing ore.

[0038] In other embodiments, the lithium-containing aqueous solution is lithium-containing groundwater.

[0039] In yet another embodiment, the lithium-containing aqueous solution is obtained by a method comprising the following steps: mechanically pulverizing at least one selected from lithium-ion batteries, lithium-ion battery waste, lithium-ion battery production waste, lithium-ion pool production waste, lithium-ion cathode active materials, and combinations thereof to obtain a black substance, and leaching the black substance to obtain an aqueous solution containing lithium.

[0040] Black substance:

[0041] "Black matter" refers to lithium-containing materials obtained from, for example, lithium-ion batteries, lithium-ion battery waste, lithium-ion battery production waste, lithium-ion pool production waste, lithium-ion cathode active materials, and / or combinations thereof, through mechanical methods such as mechanical pulverization. For example, black matter can be obtained from battery waste by mechanically processing it to obtain active components of the electrodes, such as graphite, and cathode active materials, and may contain impurities from the casing, electrode foil, cables, separator, and electrolyte. In some instances, battery waste can be subjected to heat treatment to pyrolyze organic materials (e.g., electrolyte) and polymeric materials (e.g., separator and binder). This heat treatment can be performed before or after the mechanical pulverization of the battery materials.

[0042] Lithium-ion batteries can be disassembled, stamped, milled (e.g., in a hammer mill), and / or shredded (e.g., in an industrial shredder). This machining process yields the active materials for the battery electrodes. Lightweight fractions (such as casing portions made of organic plastics and aluminum or copper foil) can be removed, for example, by forced airflow, air separation, or grading.

[0043] Battery waste can originate from, for example, used batteries or manufacturing waste such as substandard materials. In some embodiments, battery materials are obtained from mechanically processed battery waste, such as from battery waste processed in a hammer mill or industrial shredder. Such materials may have an average particle size (D50) ranging from 1 pm to 1 cm, such as 1 to 500 pm, and further, for example, 3 to 250 pm.

[0044] A significant portion of battery waste, such as the casing, wiring, and electrode carrier film, can be mechanically separated, allowing the corresponding materials to be removed from the battery materials used in this method.

[0045] Mechanically processed battery waste can be subjected to solvent treatment to dissolve and separate polymeric binders used for bonding transition metal oxides to current collector membranes, or for example, for bonding graphite to current collector membranes. Suitable solvents are N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, N-ethylpyrrolidone, and dimethyl sulfoxide, in pure form, as a mixture of at least two of the foregoing, or as a mixture with 1% to 99% water by weight.

[0046] Mechanically processed battery waste can be subjected to heat treatment in different atmospheres and over a wide temperature range. The temperature range is typically from 100°C to 900°C. Lower temperatures below 300°C can be used to evaporate residual solvents in the battery electrolyte. At higher temperatures, binder polymers may decompose, while at temperatures above 400°C, the composition of inorganic materials may change because some transition metal oxides may be reduced by carbon contained in the waste material or by the introduction of reducing gases. In some embodiments, the reduction of lithium metal oxides can be avoided by maintaining the temperature below 400°C and / or by removing carbon-containing materials prior to heat treatment.

[0047] In some embodiments, the battery material includes at least one selected from lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium metal phosphate, lithium-ion battery waste, black material derived from lithium-ion batteries, and combinations thereof.

[0048] In some embodiments, the battery material includes materials having the formula Li x MPO4 is a lithium metal phosphate, where x is an integer greater than or equal to 1, and M is selected from metals, transition metals, rare earth metals, and combinations thereof.

[0049] In some embodiments, the battery material includes materials having the formula Li 1+x (Ni a Co b Mn c M1 d ) 1-xLithated nickel cobalt manganese oxide of O2, wherein M1 is selected from Mg, Ca, Ba, Al, Ti, Zr, Zn, Mo, V and Fe, 0 < x < 0.2, 0.1 < a < 0.95, 0 < b < 0.9 (e.g. 0.05 < b < 0.5), 0 < c < 0.6, 0 < d < 0.1, and a + b + c + d = 1.

[0050] Exemplary lithium-ion nickel-cobalt-manganese oxides include

[0051] Li (1+x) [Ni 0.33 Co 0.33 Mn 0.33 ] (1-x) O2,

[0052] Li (1+x) [Ni 0.5 Co 0.2 Mn 0.3 ] (1-x) O2,

[0053] Li (1+x) [Ni 0.6 Co 0.2 Mn 0.2 ] (1-x) O2,

[0054] Li (1+x) [Ni 0.7 Co 0.2 Mn 0.1 ] (1-x) O2,

[0055] Li (1+x) [Ni 0.8 Co 0.1 Mn 0.1 ] (1-x) O2 (each of which has x as defined above), and

[0056] Li[Ni 0.85 Co 0.13 Al 0.02 O2.

[0057] In some embodiments, the battery material includes materials having the formula Li[Ni] h Co i Al j ]O 2+r The lithium-ionized nickel cobalt aluminum oxide, wherein h ranges from 0.8 to 0.90, i ranges from 0.1 to 0.3, j ranges from 0.01 to 0.10, and r ranges from 0 to 0.4.

[0058] In some embodiments, the battery material comprises nickel, cobalt, manganese, copper, aluminum, iron, phosphorus, or combinations thereof. In some embodiments, the battery material has a weight ratio of lithium to the total weight of nickel, cobalt, manganese, copper, aluminum, iron, and phosphorus ranging from 0.01 to 100. In some embodiments, the battery material has a weight ratio of lithium to the total weight of nickel, cobalt, manganese, copper, aluminum, iron, and phosphorus ranging from 0.01 to 10. In some embodiments, the battery material has a weight ratio of lithium to the total weight of nickel, cobalt, manganese, copper, aluminum, iron, and phosphorus ranging from 0.01 to 5. In some embodiments, the battery material has a weight ratio of lithium to the total weight of nickel, cobalt, manganese, copper, aluminum, iron, and phosphorus ranging from 0.01 to 2. In some embodiments, the battery material has a weight ratio of lithium to the total weight of nickel, cobalt, manganese, copper, aluminum, iron, and phosphorus ranging from 0.01 to 1.

[0059] In some embodiments, the battery material includes Li x MO2, where x is an integer greater than or equal to 1, and M is selected from metals, transition metals, rare earth metals, and combinations thereof. In some embodiments, a method for recycling lithium-ion battery materials includes mechanically pulverizing at least one selected from lithium-ion batteries, lithium-ion battery waste, lithium-ion battery production waste, lithium-ion pool production waste, lithium-ion cathode active materials, and combinations thereof to obtain a black substance.

[0060] This disclosure also provides a method for recycling lithium-ion battery materials, the method comprising: mechanically pulverizing at least one selected from lithium-ion batteries, lithium-ion battery waste, lithium-ion battery production waste, lithium-ion pool production waste, lithium-ion cathode active materials, and combinations thereof to obtain a black substance; leaching the black substance to obtain an aqueous solution containing lithium; and treating the aqueous solution by electrolysis as described above.

[0061] This disclosure also provides an apparatus for performing the method disclosed herein, namely an electrolytic cell. The electrolytic cell includes at least one EOL PFAS membrane. In some embodiments, the electrolytic cell includes at least two EOL PFAS membranes.

[0062] An electrolytic cell includes a cathode and an anode. In some embodiments, the electrolytic cell may be configured as a unipolar or bipolar configuration. The cathode may be any cathode known for electrolyzing an aqueous solution containing lithium. The anode may be any anode known for electrolyzing an aqueous solution containing lithium. In some embodiments, the anode is at least one selected from metal electrodes, metal oxide electrodes, electrodes coated with platinum group metals, and electrodes coated with platinum group metal oxides. In some embodiments, the thickness of the coating on the anode ranges from 1 micrometer to 100 micrometers. In some embodiments, the anode is titanium. In some embodiments, the anode has a geometry selected from mesh, plate, wire, foam, and felt. In some embodiments, the anode is sheet-like, rod-like, flat, corrugated, rectangular, asymmetrical, or a combination thereof. In some embodiments, the anode has iridium oxide coated on a titanium substrate. In some embodiments, the anode comprises a conductive substrate having a surface coating of a metal oxide doped with at least one noble metal. In some embodiments, the metal oxide is selected from titanium, tantalum, niobium, zirconium, and combinations thereof. In some embodiments, the noble metal is selected from platinum, ruthenium, palladium, iridium, rhodium, osmium, and combinations thereof. In some embodiments, the cathode is at least one selected from metal electrodes, metal oxide electrodes, electrodes having platinum group metals, and electrodes coated with platinum group metal oxides. In some embodiments, the thickness of the coating on the cathode ranges from 1 micrometer to 100 micrometers. In some embodiments, the cathode is at least one selected from nickel electrodes and stainless steel electrodes. In some embodiments, the cathode has a geometry selected from mesh, plate, wire, foam, and felt. In some embodiments, the cathode is sheet-like, rod-like, flat, corrugated, rectangular, asymmetrical, or a combination thereof. In some embodiments, the cathode is a stainless steel electrode. In some embodiments, the cathode is selected from porous metals. In some embodiments, the cathode comprises stainless steel, nickel, cobalt, titanium, steel, lead, platinum, and combinations thereof.

[0063] In some embodiments, spacers are positioned between the cathode and the EOL PFAS membrane, and between the anode and the EOL PFAS membrane in the electrolytic cell. Spacers help extend the lifespan of the cation exchange membrane. In some embodiments, the total thickness of the spacers ranges from 0.5 to 3 mm, and the thickness of a single spacer ranges from 0.3 to 2 mm. In some embodiments, the spacers are characterized by a mesh structure with openings of 0.5 × 0.5 mm or larger, such as 2 × 2 mm. In some embodiments, the mesh structure is composed of filaments with a diameter ranging from 0.5 to 1.5 mm, such as 1 mm. In some embodiments, the spacers are made of polyethylene (PE) or polypropylene (PP).

[0064] In some embodiments, the electrolytic cell is a three-chamber membrane electrolytic cell. In other embodiments, the electrolytic cell is a two-chamber membrane electrolytic cell.

[0065] In some embodiments, the electrolytic cell is a bipolar electrolytic cell. For example, the electrolytic cell may be a bipolar three-chamber electrolytic cell.

[0066] In some embodiments, an electrolytic cell is an electrolytic cell in which a cathode chamber is separated from a central chamber or an anode chamber by a cation exchange membrane.

[0067] In some embodiments, at least one, at least two, at least 10, at least 100, or at least 500 electrolytic cells are stacked one after another in fluid communication. The electrolytic cell stack has an inlet and an outlet.

[0068] In some embodiments, electrolysis is performed using an electrolytic reactor comprising a three-chamber cell equipped with a monopolar membrane and bipolar electrodes. Such electrodes are effective for releasing gaseous hydrogen (H2) at the cathode electrode and gaseous oxygen (O2) at the anode electrode. These electrodes are also effective for splitting water molecules.

[0069] In an exemplary method, electrolysis is performed by introducing an aqueous composition containing lithium sulfate into a central chamber, introducing an aqueous composition containing lithium hydroxide into a cathode chamber, and generating an aqueous composition containing sulfuric acid in an anode chamber.

[0070] In another exemplary method, electrolysis is performed by introducing an aqueous composition containing lithium sulfate into the chambers of a two-chamber electrolytic cell, generating hydrogen and an aqueous composition containing lithium hydroxide in the cathode chamber, and generating oxygen and an aqueous composition containing sulfuric acid and lithium sulfate in the anode chamber.

[0071] During electrolysis, the aqueous composition containing lithium hydroxide can be maintained at a lithium hydroxide concentration of at least substantially 30 to 90 g / L, about 40 to 90 g / L, about 35 to 70 g / L, about 40 to 66 g / L, about 45 to 65 g / L, about 48 to 62 g / L, or about 50 to 60 g / L.

[0072] During electrolysis, the aqueous composition containing lithium hydroxide can be maintained at a lithium hydroxide concentration of at least substantially between about 1 and about 5 M, about 2 and about 4 M, about 2.5 and about 3.5 M, about 2.7 and about 3.3 M, about 2.9 and about 3.1 M, or about 3 M.

[0073] During electrolysis, the aqueous composition containing sulfuric acid can be maintained at a sulfuric acid concentration of at least approximately 30 to approximately 100 g / L, approximately 40 to approximately 100 g / L, approximately 40 to approximately 100 g / L, approximately 60 to approximately 90 g / L, approximately 20 to approximately 40 g / L, approximately 20 to approximately 50 g / L, approximately 25 to approximately 35 g / L, or approximately 28 to approximately 32 g / L.

[0074] During electrolysis, the aqueous composition containing sulfuric acid can be maintained at a sulfuric acid concentration of at least substantially 0.1 to about 5 M, about 0.2 to about 3 M, about 0.3 to about 2 M, about 0.3 to about 1.5 M, about 0.4 to about 1.2 M, about 0.5 to about 1 M, or about 0.75 M.

[0075] During electrolysis, the aqueous composition containing lithium sulfate can be maintained at a lithium sulfate concentration of at least substantially between about 5 and about 30 g / L, between about 5 and about 25 g / L, between about 10 and about 20 g / L, or between about 13 and about 17 g / L.

[0076] During electrolysis, the aqueous composition containing lithium sulfate can be maintained at a lithium sulfate concentration of at least substantially between about 0.2 M and about 3 M, about 0.4 M and about 2.5 M, about 0.5 M and about 2 M, or about 0.6 M and about 1.8 M.

[0077] During electrolysis, the temperature of the aqueous composition containing lithium sulfate or other lithium compounds can be maintained at least substantially at values ​​of about 20°C to about 80°C, about 20°C to about 60°C, about 30°C to about 40°C, about 50°C to about 60°C, or about 46°C to about 54°C.

[0078] During this method, the voltage can be maintained at least substantially at a constant value of about 3 to about 10 V or about 4 to about 7 V. For example, the cell voltage can be maintained at least substantially at values ​​of about 1.0 V to about 8.5 V, about 1.0 V to about 3.0 V, about 2.0 V to about 3.0 V, about 3.0 V to about 8.5 V, about 6.5 V to about 8 V, about 5.5 V to about 6.5 V, or about 6 V.

[0079] This disclosure also provides information on the use of spent PFAS membranes in the electrolysis of lithium sulfate solutions.

[0080] In summary, the advantages of the disclosed methods and apparatus include providing the opportunity to reuse spent PFAS membranes in the electrolysis of lithium sulfate solutions, thereby avoiding the disposal or incineration of used PFAS membranes. Furthermore, the operating costs of lithium sulfate electrolysis can be significantly reduced when spent PFAS membranes are used in an electrochemical cell. The spent PFAS membranes are fully hydrated and exhibit less swelling during the ramp-up phase of electrolysis. The spent PFAS membranes exhibit similar performance to virgin PFAS membranes.

[0081] Detailed description of the attached figures

[0082] Figure 1 An exemplary electrolytic cell 100 is depicted. An aqueous solution 101 containing lithium can be supplied to the electrolytic cell 100. In some embodiments, the aqueous solution 101 containing lithium is obtained by a method comprising the steps of: mechanically pulverizing at least one selected from lithium-ion batteries, lithium-ion battery waste, lithium-ion battery production waste, lithium-ion cell production waste, lithium-ion cathode active materials, and combinations thereof to obtain a black substance, and leaching the black substance to obtain an aqueous solution containing lithium. In some embodiments, the aqueous solution 101 containing lithium is obtained by leaching lithium-containing ore. In some embodiments, the aqueous solution 101 containing lithium is lithium-containing groundwater. In some embodiments, the aqueous solution containing lithium is obtained by leaching battery materials. In some electrolytic cells (such as...) Figure 1 In the exemplary pool depicted, one or more cation exchange membranes 113 may be present. Figure 1 Two such films 113 are depicted as vertical lines. Positive ions (such as Li) + ) tend to migrate toward the negatively charged electrode 110, while negative ions (such as SO42-) 2- The protons tend to migrate towards the positively charged electrode 111. During electrolysis, alkaline hydroxide ions can form near the negative electrode 110 and can increase the local pH. During electrolysis, acidic protons can form near the positive electrode 111 and can decrease the local pH. A lithium-rich and / or more alkaline aqueous solution 102 can be obtained near the negative electrode 110. A lithium-depleted and / or more acidic aqueous solution 104 can be obtained near the positive electrode 111. An aqueous solution 103, which may be lithium-depleted and / or more acidic, lithium-rich and / or more alkaline, or have substantially the same lithium concentration and / or pH as the feed solution 101, can also be obtained in the central chamber. Here, enriched, depleted, more alkaline, and more acidic each refer to the characteristics of the supplied lithium-containing aqueous solution 101. In some electrolytic cells (such as...) Figure 1 In the exemplary cell depicted, a spacer 112 may be present between electrodes 110, 111 and the cation exchange membrane 113. The spacer prevents direct contact between electrodes 110, 111 and the cation exchange membrane 113. Figure 1 In other embodiments not shown, spacers are also present between the cation exchange membranes 113.

[0083] Figure 2 Showing Nafion TMA graph showing the electrode temperature versus time during long-term test runs of electrolytic cells containing N438 cation exchange membranes (spherical – N438 without spacers, triangular – N438 with spacers). Thermocouples attached to the anode and cathode monitored the electrode temperatures during the long-term tests. The cell tests without spacers revealed electrode temperatures well above 100°C (anode and cathode) after hundreds of hours of direct testing. After disassembling such cells, changes in the cation exchange membrane could be visually observed. Certain areas of the polymer membrane in contact with the electrodes had turned brown, and these areas appeared hard and brittle. It is speculated that the polymer membrane began to degrade at the elevated temperatures. This is a self-propagating process that progresses as less membrane area becomes available for the electrolytic process. This, in turn, leads to higher resistance and increasing temperatures over time.

[0084] After introducing the spacer into the test cell, the electrode temperature remained significantly below 100°C. The observed cell voltage remained very constant when using the spacer, although it was slightly higher due to the increased electrode gap. It is presumed that the use of the spacer improves gas transport and the wettability of the membrane / electrode with the electrolyte. This ultimately leads to full utilization of the entire electrode and membrane region within the test cell. (Using NORSCAND) ® The results were observed in an NS-01 two-chamber test cell (NORAM Electrolysis Systems Inc., Vancouver, British Columbia V6C 1S4, Canada). Different electrolyzers may exhibit other performance characteristics.

[0085] The thickness of each spacer increased the distance between the two electrodes. As a result, an increase in cell voltage of 500 to 600 mV was observed. When using large spacers, the average cell voltage was between 5.8 and 5.9 V. Cells without spacers exhibited an average cell voltage ranging from 5.3 to 5.4 V.

[0086] Figure 3 It shows the use of the original Nafion TM Electrolyzer using N438 cation exchange membrane and EOL Nafion TM A graph showing the cell voltage versus time in an electrolyzer with an N438 cation exchange membrane. The EOL membrane has a thickness of 405 µm, while the original membrane has a thickness of 361 µm. Membrane thickness was measured using a Sony DZ521 stage. In the electrolyzer with the original membrane, the current density gradually increased during the first 200 hours, eventually reaching 400 mA / cm². 2The value of the cell voltage is shown in the corresponding graph. As can be seen, the voltage increases sharply but decays immediately after each step. After 500 hours, the cell voltage is approximately 6 V. During the following hours, the cell voltage remains close to a value slightly below 6 V. This finding matches previous results well.

[0087] Experiments using an EOL membrane confirmed the trend of cell voltage relative to time, such as... Figure 3 As shown. After more than 800 hours, the cell voltage values ​​were recorded between 5.8 and 5.9 V. The electrolytic cell with an EOL membrane maintained a voltage of 400 mA / cm throughout the test period. 2 The current density was maintained. During the initial phase of the electrolysis experiment, we observed a decrease in cell voltage due to the continuous water absorption, wetting, and swelling of the ion exchange membrane. As can be seen from the figure, the EOL membrane reached stable operation faster than the original membrane and performed comparably to the original membrane during electrolysis.

[0088] List of reference numerals

[0089] 100 Electrolytic Cell

[0090] 101 Lithium-containing aqueous solution (feed)

[0091] 102 Lithium-rich aqueous solution (cathode electrolyte)

[0092] 103. Aqueous solution containing lithium (effluent)

[0093] 104 Lithium-poor aqueous solution (anolyte)

[0094] 110 cathode

[0095] 111 anode

[0096] 112 spacer

[0097] 113 Cation Exchange Membrane.

Claims

1. A method, the method comprising i) In industrial electrolysis processes other than lithium brine electrolysis, sulfonated cation exchange membranes containing perfluoroalkyl and polyfluoroalkyl substances (PFAS) are operated for a period of time ranging from 7,500 hours to 30,000 hours to obtain waste PFAS membranes. ii) Electrolyzing lithium-containing brine in an electrochemical cell comprising at least one cation exchange membrane, wherein the at least one cation exchange membrane is the waste PFAS membrane.

2. The method as described in claim 1, wherein, This industrial electrolysis process is membrane electrolysis of sodium chloride aqueous solution.

3. The method of claim 1, wherein, This industrial electrolysis process is membrane electrolysis of an aqueous hydrogen chloride solution.

4. The method according to any one of claims 1 to 3, wherein, The waste PFAS membrane is a perfluorosulfonic acid polymer membrane.

5. The method of claim 4, wherein, The perfluorosulfonic acid polymer film contains a tetrafluoroethylene-perfluoro-3,6-dioxa-4-methyl-7-octene sulfonic acid copolymer.

6. The method according to any one of claims 1 to 5, wherein, The waste PFAS membrane has a thickness ranging from 380 µm to 420 µm.

7. The method according to any one of claims 1 to 6, wherein, The thickness of the waste PFAS membrane is in the range of 1.1 to 1.2 times the thickness of the membrane before it was used in the industrial electrolysis process.

8. The method according to any one of claims 1 to 7, wherein, The current density during this electrolysis is 0.05 A / cm². 2 Up to 2.0 A / cm 2 Within the range.

9. The method according to any one of claims 1 to 8, wherein, The cell voltage during this electrolysis process is in the range of 3 V to 7 V.

10. The method according to any one of claims 1 to 9, wherein, During this electrolysis, the temperature in the electrochemical cell is in the range of 40°C to 60°C.

11. An electrolytic cell (100) for electrolyzing lithium-containing brine (101), the electrolytic cell (100) comprising a cathode (110), an anode (111) and at least one sulfonated cation exchange membrane (113) comprising perfluoroalkyl and polyfluoroalkyl substances (PFAS) positioned between the cathode (110) and the anode (111), the sulfonated cation exchange membrane having been operated in industrial electrolysis processes other than lithium-containing brine electrolysis for a period of time ranging from 7,500 hours to 30,000 hours (used PFAS cation exchange membrane).

12. The electrolytic cell (100) as described in claim 12, wherein, The spacer (112) is positioned between the cathode (110) and the at least one waste PFAS cation exchange membrane (113), and between the anode (111) and the at least one waste PFAS cation exchange membrane (113).

13. Use of sulfonated cation exchange membranes (PFAS) containing perfluoroalkyl and polyfluoroalkyl substances (PFAS) in electrochemical cells for the electrolysis of lithium-containing brine, wherein the sulfonated cation exchange membranes have been operated in industrial electrolysis processes other than lithium-containing brine electrolysis for a period of time ranging from 7,500 hours to 30,000 hours (used PFAS cation exchange membranes).

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