Methods of recovering metals from lithium-ion or sodium-ion battery materials

Abstract

Disclosed herein are methods of recovering one or more metals from at least two active materials obtained from a lithium or sodium ion battery. A first method places: a first active material in a first redox-active molecule solution that comprises a first solvent and an uncharged first redox-active molecule to form a first redox solution comprising lithium or sodium ions and a charged first redox-active molecule in a first tank; and a second active material to a second redox-active molecule solution that comprises a second solvent and a second redox-active molecule to form a second redox solution comprising lithium or sodium ions and a charged second redox-active molecule in a second tank, where the first and second active materials either both comprise lithium ions or both comprise sodium ions. The resulting redox solutions are circulated into and out of a redox flow cell to generate energy and leach lithium or sodium ions, where the first redox-active molecule has a redox potential higher than the first active material, but lower than the second redox-active molecule and the second redox-active molecule has a redox potential lower than the second active material. A second method places: a first active material in a first solvent in a first tank to provide a first mixture; and a second active material to a second solvent in a second tank to provide a second mixture. The resulting mixtures are circulated into and out of a redox flow cell to generate energy and leach lithium or sodium ions.

Description

[0001] METHODS OF RECOVERING METALS FROM LITHIUM-ION OR SODIUM-ION BATTERY MATERIALS

[0002] FIELD OF INVENTION

[0003] The present invention relates to methods of recovering one or more metals from active materials obtained from a lithium or sodium ion battery.

[0004] BACKGROUND

[0005] Conventional leaching processes used in recycling sodium-ion batteries (NIBs) and lithium- ion batteries (LIBs) consume large amount of energy and chemicals, creating environmental concerns. Thus, there is a need for alternative and / or improved methods suitable for recovering metals from spent NIB and LIB materials and preferably, generate electricity simultaneously.

[0006] SUMMARY

[0007] Aspects and embodiments of the current invention will now be described by reference to the following numbered clauses.

[0008] 1. A method of recovering one or more metals from at least two active materials obtained from a lithium or sodium ion battery, respectively, the method comprising:

[0009] (a) providing a first active material and a second active material, each of the first and second active materials comprising lithium or sodium ions;

[0010] (b) adding: the first active material to a first redox-active molecule solution that comprises a first solvent and an uncharged first redox-active molecule to form a first redox solution comprising lithium or sodium ions and a charged first redox-active molecule in a first tank, and the second active material to a second redox-active molecule solution that comprises a second solvent and a second redox-active molecule to form a second redox solution comprising lithium or sodium ions and a charged second redox-active molecule in a second tank, wherein the first and second active materials either both comprise lithium ions or both comprise sodium ions;

[0011] (c) moving the first and second redox solutions from the first and second tanks to a redox flow cell, comprising: a first electrode compartment having a first electrode; a second electrode compartment having a second electrode; a cation exchange membrane that separates the first and second electrode compartments from one another; and a load device, where the charged first and second redox-active molecules interact via the cation exchange membrane to provide the uncharged first and second redox-active molecules, respectively and to generate electricity, which is harvested by the load device;

[0012] (d) moving the first and second redox solution comprising uncharged first and second redox-active molecules, respectively, back to the first and second tanks, respectively, to provide first and second redox solutions comprising charged first and second redox-active molecules, respectively; and

[0013] (e) repeating steps (c) and (d) until one or both of the first and second active materials are consumed, wherein: the first redox-active molecule has a redox potential higher than the first active material, but lower than the second redox-active molecule; the second redox-active molecule has a redox potential lower than the second active material; the first solvent comprises water and a supporting electrolyte; and the second solvent comprises water and an acidic supporting electrolyte.

[0014] 2. The method according to clause 1 , wherein in step (c) of clause 1 , the step of moving the first and second redox solutions from the first and second tank to a redox flow cell comprises passing the respective first and second redox solutions through a respective filtration means or apparatus that prevents solid matter entering the redox flow cell.

[0015] 3. The method according to clause 1 or clause 2, wherein the first and second active material is still attached to an electrode of a dismantled sodium- or lithium-ion battery or is provided free from the electrode.

[0016] 4. The method according to any one of the preceding clauses, wherein one or both of the following apply: the first redox-active molecule has a redox potential higher than the first active material of from 20 to 500 mV, such as from 40 to 250 mV, such as from 50 to 100 mV, such as about 70 mV; and the second redox-active molecule has a redox potential lower than the second active material of from 50 to 500 mV, such as from 80 to 300 mV, such as from 100 to 250 mV, such as about 220 mV, where the redox potentials of the first active material, the second active material, the first redox-active molecule and the second redox-active molecule are measured versus a standard hydrogen electrode. 5. The method according to any one of the preceding clauses, wherein the first active material is selected from one or more of NaFePC , LixFePC (where 0 < x < 1) and LixMnyFezPO4, (where 0 < x, y, z < 1), such as LiFePC>4, and provided that the active material only contains one of lithium ions or sodium ions.

[0017] 6. The method according to any one of the preceding clauses, wherein the second active material is selected from one or more of NaxCoO2, LiNixCoyMnzO2 (NCM, where 0 < x,y,z < 1), LixCoCt (where 0 < x < 1), LiNixCoyAlzO2 (NCA, where x > 0.8, z < 0.05 and x + y + z = 1), LixMn2O4 (where 0 < x < 1), and LixNio5Mn1.5O4 (where 0 < x < 1) and provided that the active material only contains one of lithium ions or sodium ions, optionally wherein the second active material is selected from one or more of LixNiCoMnO2, LixCoO2, LixNiCoAIO2, LixM^C , LixNio.5Mn1.5O4, such as LixCoO2, where 0 <x< 1 and provided that the active material only contains one of lithium ions or sodium ions.

[0018] 7. The method according to any one of the preceding clauses, wherein: when the first active material comprises lithium ions, then the first redox-active molecule is selected from one or more of the group consisting of a quinine and derivatives thereof, and more particularly, a ferricyanide (Li3Fe(CN)s), a ferrocyanide (Li4Fe(CN)5), ferrocene (CioHwFe) and derivatives thereof, and an iodide (Lil); or when the first active material comprises sodium ions, then the first redox-active molecule is selected from one or more of the group consisting of a quinone and derivatives thereof, a ferricyanide (Na3Fe(CN)8), a ferrocyanide (Na4Fe(CN)s), ferrocene (CioHioFe) and derivatives thereof, and an iodide (Nal).

[0019] 8. The method according to any one of the preceding clauses, wherein when the first active material comprises lithium ions, then the first redox-active molecule is a ferrocyanide (M4Fe(CN)e), such as Li4Fe(CN)e.

[0020] 9. The method according to any one of the preceding clauses, wherein one or more of the following apply: the total concentration of the first redox-active molecule present in the first solvent is from 0.05 M to 1 .5 M, such as about 0.4 M; the neutral supporting electrolyte is one or more of lithium sulfate or more particularly lithium acetate, and lithium dihydrogen phosphate; and the supporting electrolyte is present at a concentration of from 0.5 to 4 M, such as from 0.75 to 1.5 M, such as about 1 M in the first redox-active molecule solution. 10. The method according to any one of the preceding clauses, wherein the second redoxactive molecule is selected from one or more of the group consisting of benzoquinone disulfonic acid, hydroquinone sulfonic acid and, when the second active material comprises lithium ions (e,g, lithium bromide).

[0021] 11. The method according to any one of the preceding clauses, wherein the second redoxactive molecule is benzoquinone disulfonic acid.

[0022] 12. The method according to any one of the preceding clauses, wherein one or more of the following apply: the total concentration of the second redox-active molecule present in the second solvent is from 0.05 M to 1.5 M, such as from 0.75 to 0.5 M, such as about 0.1 M; the acidic supporting electrolyte is an inorganic acid or an organic acid; and the acidic supporting electrolyte is present at a concentration of from 0.5 to 4 M, such as from 0.75 to 2 M, such as about 1.5 M in the second redox-active molecule solution.

[0023] 13. The method according to clause 12, wherein: the inorganic acid is selected from one or more of hydrochloric acid, nitric acid, and. more particularly, sulfuric acid; the organic acid is selected from one or more of oxalic acid, and more particularly citric acid, and acetic acid.

[0024] 14. A method of recovering one or more metals from at least two active materials obtained from a lithium or sodium ion battery, respectively, the method comprising:

[0025] (a) providing a first active material and a second active material, each of the first and second active materials comprising lithium or sodium ions, where the first and second active materials either both comprise lithium ions or both comprise sodium ions;

[0026] (b) adding: the first active material to a first solvent in a first tank to provide a first mixture, and the second active material to a second solvent in a second tank to provide a second mixture;

[0027] (c) moving the first and second mixtures from the first and second tanks to a redox flow cell and returning the first and second mixtures to the first and second tanks, respectively, the redox flow cell comprising: a first electrode compartment having a first electrode; a second electrode compartment having a second electrode; a cation exchange membrane or a porous separator membrane that separates the first and second electrode compartments from one another; and a load device, where the first and second mixtures interact via the cation exchange or porous separator membrane to provide one or more species of metal ions and to generate electricity, which is harvested by the load device;

[0028] (d) repeating step (c) until one or both of the first and second active materials are consumed, wherein: the first solvent comprises water and a supporting electrolyte; and the second solvent comprises water and an acidic supporting electrolyte.

[0029] 15. The method of clause 14, wherein the first and second active materials are provided in a particulate form and particles of the first and second active materials are allowed to circulate from the first and second tanks into the first and second electrode compartments, respectively.

[0030] 16. The method according to clause 14 or clause 15, wherein the first active material is selected from one or more of NaFePC>4, LixFePO4 (where 0 < x < 1) and LixMnyFezPO4, (where 0 < x, y, z < 1), such as LiFePC , and LixFePC>4, such as LixFePC>4, where 0 <x< 1 and provided that the active material only contains one of lithium ions or sodium ions, optionally wherein the first active material is selected from one or more of NaFePC and LixFePC , such as LixFePO4, where 0 <x< 1 and provided that the active material only contains one of lithium ions or sodium ions.

[0031] 17. The method according to any one of clauses 14 to 16, wherein the second active material is selected from one or more of NaCoC>2, LiNixCoyMnzO2 (NCM, where 0 < x,y,z < 1), LixCoCt (where 0 < x < 1), LiNixCoyAlzO2 (NCA, where x > 0.8, z < 0.05 and x + y + z = 1), LixMn2O4 (where 0 < x < 1), and LixNio 5Mn1.5O4 (where 0 < x < 1), such as LiCoO2, and provided that the active material only contains one of lithium ions or sodium ions optionally wherein the second active material is selected from one or more of, LixNiCoMnO2, LixCoO2, LixNiCoAIO2, LixMn2O4, LixNio.5Mn1 5O4, such as LixCoO2, where 0 <x< 1 and provided that the active material only contains one of lithium ions or sodium ions.

[0032] 18. The method according to any one of clauses 14 to 17, wherein one or both of the following apply: the neutral supporting electrolyte is one or more of lithium sulfate, and more particularly lithium acetate and lithium dihydrogen phosphate; and the supporting electrolyte is present at a concentration of from 0.5 to 4 M, such as from 0.75 to 1.5 M, such as about 1 M in the first mixture.

[0033] 19. The method according to any one of clauses 14 to 18, wherein one or both of the following apply: the acidic supporting electrolyte is an inorganic acid of an organic acid; and the acidic supporting electrolyte is present at a concentration of from 0.5 to 4 M, such as from 0.75 to 2 M, such as about 1.5 M in the second mixture.

[0034] 20. The method according to clause 19, wherein: the inorganic acid is selected from one or more of hydrochloric acid, nitric acid, and. more particularly, sulfuric acid; the organic acid is selected from one or more of oxalic acid, and more particularly citric acid, acetic acid.

[0035] BRIEF DESCRIPTION OF DRAWINGS

[0036] FIG. 1 is a schematic illustration of the method of recovering metals from spent Li-ion battery materials via a flow cell involving two redox-active molecules (RAMs) according to Example 1 of the present disclosure.

[0037] FIG. 2 includes (a) cyclic voltammetry (CV) curves of 100 mM Li4Fe(CN)a in 1 M lithium acetate compared with LFP in 1 M lithium acetate, and 100 mM BQDS in 0.5 M H2SO4 and LCO in 0.5 M H2SO4. (b) Voltage profile of the flow cell using LFP as negolyte fuel and 400 mM Li4Fe(CN)e in 1 M lithium acetate as negolyte paired with LCO as posolyte fuel and 100 mM BQDS in 1.5 M H2SO4 as posolyte. The current density was 10 mA cm'2, (c) XRD patterns of residue in tank I compared with LFP and FP. (d) XRD patterns of residue in tank II compared with LCO.

[0038] FIG. 3 is a schematic illustration of the method of recovering metals from spent Li-ion battery materials via a semi-solid flow cell according to Example 2 of the present disclosure

[0039] FIG. 4 is a voltage profile of the flow cell using LFP slurry in 1 M lithium acetate as negolyte paired with LCO slurry in 1.5 M H2SO4 as posolyte. The current density was 1 mA cm'2.

[0040] DESCRIPTION The present inventors have developed methods to recover one or more metals from active materials obtained from a lithium / sodium ion battery. The methods disclosed herein enable the simultaneous leaching of spent active materials from a battery (e g. LiCoC NMC and LiFePC>4) via the assistance of flow cell setup. This means that all chemicals used can be regenerated instantaneously. There is no or minimum consumption of other chemicals used in the method. In addition, the leaching processes disclosed herein, also enables energy generation, which can be used to compensate for the energy consumed, reducing overall utility costs.

[0041] In a first aspect of the invention, there is provided a method of recovering one or more metals from at least two active materials obtained from a lithium or sodium ion battery, respectively, the method comprising:

[0042] (a) providing a first active material and a second active material, each of the first and second active materials comprising lithium or sodium ions;

[0043] (b) adding: the first active material to a first redox-active molecule solution that comprises a first solvent and an uncharged first redox-active molecule to form a first redox solution comprising lithium or sodium ions and a charged first redox-active molecule in a first tank, and the second active material to a second redox-active molecule solution that comprises a second solvent and a second redox-active molecule to form a second redox solution comprising lithium or sodium ions and a charged second redox-active molecule in a second tank, wherein the first and second active materials either both comprise lithium ions or both comprise sodium ions;

[0044] (c) moving the first and second redox solutions from the first and second tanks to a redox flow cell, comprising: a first electrode compartment having a first electrode; a second electrode compartment having a second electrode; a cation exchange membrane that separates the first and second electrode compartments from one another; and a load device, where the charged first and second redox-active molecules interact via the cation exchange membrane to provide the uncharged first and second redox-active molecules, respectively and to generate electricity, which is harvested by the load device;

[0045] (d) moving the first and second redox solution comprising uncharged first and second redox-active molecules, respectively, back to the first and second tanks, respectively, to provide first and second redox solutions comprising charged first and second redox-active molecules, respectively; and (e) repeating steps (c) and (d) until one or both of the first and second active materials are consumed, wherein: the first redox-active molecule has a redox potential higher than the first active material, but lower than the second redox-active molecule; the second redox-active molecule has a redox potential lower than the second active material; the first solvent comprises water and a supporting electrolyte; and the second solvent comprises water and an acidic supporting electrolyte.

[0046] In embodiments herein, the word “comprising” may be interpreted as requiring the features mentioned, but not limiting the presence of other features. Alternatively, the word “comprising” may also relate to the situation where only the components / features listed are intended to be present (e.g. the word “comprising” may be replaced by the phrases “consists of” or “consists essentially of”). It is explicitly contemplated that both the broader and narrower interpretations can be applied to all aspects and embodiments of the present invention. In other words, the word “comprising” and synonyms thereof may be replaced by the phrase “consisting of’ or the phrase “consists essentially of’ or synonyms thereof and vice versa.

[0047] The phrase, “consists essentially of’ and its pseudonyms may be interpreted herein to refer to a material where minor impurities may be present. For example, the material may be greater than or equal to 90% pure, such as greater than 95% pure, such as greater than 97% pure, such as greater than 99% pure, such as greater than 99.9% pure, such as greater than 99.99% pure, such as greater than 99.999% pure, such as 100% pure.

[0048] In certain embodiments, in step (c) of the method above, the step of moving the first and second redox solutions from the first and second tank to a redox flow cell may comprise passing the respective first and second redox solutions through a respective filtration means or apparatus that prevents solid matter entering the redox flow cell.

[0049] In certain embodiments, the first and second active material may still be attached to an electrode of a dismantled sodium- or lithium-ion battery or is provided free from the electrode.

[0050] In certain embodiments, the first redox-active molecule may have a redox potential higher than the first active material of from 20 to 500 mV, such as from 40 to 250 mV, such as from 50 to 100 mV, such as about 70 mV. In certain embodiments, the second redox-active molecule may have a redox potential lower than the second active material of from 50 to 500 mV, such as from 80 to 300 mV, such as from 100 to 250 mV, such as about 220 mV. In certain embodiments, the redox potentials of the first active material, the second active material, the first redox-active molecule and the second redox-active molecule may be measured versus a standard hydrogen electrode.

[0051] When used herein, the term "about", in the context of redox potential and concentrations of components in a solvent / solution, may mean a variation of ± 5% of the stated value, more typically + / - 4% of the stated value, more typically ± 3% of the stated value, more typically, + / - 2% of the stated value, even more typically ± 1% of the stated value, and even more typically + / - 0.5% of the stated value.

[0052] As disclosed herein, the term “active material” refers to any suitable electroactive material, including an anode or a cathode material (such as LiFePC^ and NaCoCk) which is capable of taking part in an electrode reaction. In certain embodiments, the first active material may be selected from one or more of NaFePC , LixFePC (where 0 < x < 1) and LixMnyFezPO4, (where 0 < x, y, z < 1), and provided that the active material only contains one of lithium ions or sodium ions. In certain exemplary embodiments, the first active material may be LiFePC .

[0053] In certain embodiments, the second active material may be selected from one or more of NaxCoO2, more particularly, LiNixCoyMnzO2 (NCM, where 0 < x,y,z < 1), LixCoC>2 (where 0 < x < 1), LiNixCoyAlzO2 (NCA, where x > 0.8, z < 0.05 and x + y + z = 1), LixMn2O4 (where 0 < x < 1), LixNio 5Mni504 (where 0 < x < 1), such as LiCoO2, and provided that the active material only contains one of lithium ions or sodium ions. In certain exemplary embodiments, the second active material may be LiCoC>2. In further embodiments that may be mentioned herein the second active material may be selected from one or more of LixNiCoMnO2, LixCoO2, LixNiCoAIO2, LixMn2O4, LixNi0sMorsC , such as l_ixCoO2, where 0 <x< 1 and provided that the active material only contains one of lithium ions or sodium ions.

[0054] As disclosed herein, the term “redox-active molecule (RAM)” refers to any suitable molecule (e.g. (such as ferrocyanides and benzoquinone disulfonic acid) or, in some further embodiments, inorganic ionic species (such Fe2+, Cl' and I') which contains a redox component acting as the charge-storage center. The RAM may or may not be a molecule which contains a redox component acting as the charge-storage center surrounded by insulators / barriers formed by the linkage and the surface group. In certain embodiments, when the first active material comprises lithium ions, then the first redox-active molecule may be selected from one or more of the group consisting of a quinone and derivatives thereof, and more particularly a ferricyanide (Li3Fe(CN)e), a ferrocyanide (Li4Fe(CN)e), ferrocene (CwHioFe) and derivatives thereof, and an iodide (Lil). In other embodiments, when the first active material comprises sodium ions, then the first redox-active molecule may be selected from one or more of the group consisting of a quinone and derivatives thereof, and more particularly a ferricyanide (NasFe(CN)6), a ferrocyanide (Na4Fe(CN)e), ferrocene (C-ioH-ioFe) and derivatives thereof, and an iodide (Nal). In certain exemplary embodiments, when the first active material comprises lithium ions, then the first redox-active molecule may be a ferrocyanide (M4Fe(CN)e), such as Li4Fe(CN)6.

[0055] When used herein, the term “a quinone and derivatives thereof” refers to any aromatic compound (such as benzene or naphthalene) with an even number of carbonyl groups (for example, two carbonyl groups) at various locations and derivatives thereof, for example, 1 ,2- benzoquinone, 1 ,4-naphthoquinone, 9,10-anthraquinone, tetrachloro-1,4-benzoquinone, 2- hydroxynaphthalene-1 ,4-dione and 1 ,2-dihydroxyanthracene-9, 10-dione.

[0056] In embodiments of the first aspect of the invention, one or more of the following may apply: the total concentration of the first redox-active molecule may be present in the first solvent from 0.05 M to 1 .5 M, such as about 0.4 M; the neutral supporting electrolyte may be one or more of lithium sulfate, and more aprticularly lithium acetate, and lithium dihydrogen phosphate; and the supporting electrolyte may be present at a concentration of from 0.5 to 4 M, such as from 0.75 to 1 .5 M, such as about 1 M in the first redox-active molecule solution.

[0057] In certain embodiments, the second redox-active molecule may be selected from one or more of the group consisting of benzoquinone disulfonic acid, hydroquinone sulfonic acid and, when the second active material comprises lithium ions (e,g, lithium bromide). In certain exemplary embodiments, the second redox-active molecule is benzoquinone disulfonic acid.

[0058] In embodiments of the first aspect of the invention, one or more of the following apply: the total concentration of the second redox-active molecule may be present in the second solvent from 0.05 M to 1.5 M, such as from 0.75 to 0.5 M, such as about 0.1 M; the acidic supporting electrolyte electrolyte may be an inorganic acid or an organic acid; and the acidic supporting electrolyte may be present at a concentration of from 0.5 to 4 M, such as from 0.75 to 2 M, such as about 1.5 M in the second redox-active molecule solution. In certain embodiments, the inorganic acid may be selected from one or more of hydrochloric acid, nitric acid, and more particularly, sulfuric acid; the organic acid may be selected from one or more of oxalic acid, and more particularly citric acid, and acetic acid.

[0059] In a second aspect of the invention, there is provided a method of recovering one or more metals from at least two active materials obtained from a lithium or sodium ion battery, respectively, the method comprising:

[0060] (a) providing a first active material and a second active material, each of the first and second active materials comprising lithium or sodium ions, where the first and second active materials either both comprise lithium ions or both comprise sodium ions;

[0061] (b) adding: the first active material to a first solvent in a first tank to provide a first mixture, and the second active material to a second solvent in a second tank to provide a second mixture;

[0062] (c) moving the first and second mixtures from the first and second tanks to a redox flow cell and returning the first and second mixtures to the first and second tanks, respectively, the redox flow cell comprising: a first electrode compartment having a first electrode; a second electrode compartment having a second electrode; a cation exchange membrane or a porous separator membrane that separates the first and second electrode compartments from one another; and a load device, where the first and second mixtures interact via the cation exchange or porous separator membrane to provide one or more species of metal ions and to generate electricity, which is harvested by the load device;

[0063] (d) repeating step (c) until one or both of the first and second active materials are consumed, wherein: the first solvent comprises water and a supporting electrolyte; and the second solvent comprises water and an acidic supporting electrolyte.

[0064] In certain embodiments, the first and second active materials in this second aspect of the invention, may be provided in a particulate form and particles of the first and second active materials are allowed to circulate from the first and second tanks into the first and second electrode compartments, respectively. For example, when the first and second active materials are provided in a particulate form, the first and second active material particulates may have a diameter of less than about 100 pm. In certain embodiments, the first active material in the second aspect of the invention may be selected from one or more of NaFePC>4, LixFePC (where 0 < x < 1) and LixMnyFezPO4, (where 0 < x, y, z < 1), such as LiFePC ,, where 0 <x< 1 and provided that the active material only contains one of lithium ions or sodium ions. In certain exemplary embodiments, the first active material may be LiFePC . In further embodiments, the first active material in the second aspect of the invention may be selected from one or more of NaFePO4 and LixFePO4 (where 0 < x < 1), such as LixFePC>4 where 0 <x< 1 and provided that the active material only contains one of lithium ions or sodium ions.

[0065] In certain embodiments, the second active material in the second aspect of the invention may be selected from one or more of NaCoCh, LiNixCoyMnzO2 (NCM, where 0 < x,y,z < 1), l_ixCoC>2 (where 0 < x < 1), LiNixCoyAlzO2 (NCA, where x > 0.8, z < 0.05 and x + y + z = 1), LixM^C (where 0 < x < 1), and LixNio 5Mn1.5O4 (where 0 < x < 1) and provided that the active material only contains one of lithium ions or sodium ions, optionally wherein the second active material is selected from one or more of LixNiCoMnO2, LixCoO2, LixNiCoAIO2, LixMn2O4, LixNio.5Mn1 5O4, such as LixCoO2, where 0 <x< 1 and provided that the active material only contains one of lithium ions or sodium ions.

[0066] . In certain exemplary embodiments, the second active material may be UCOO2.

[0067] In certain embodiments, the neutral supporting electrolyte may be one or more of lithium sulfate, and more particularly lithium acetate and lithium dihydrogen phosphate. The supporting electrolyte may be present at a concentration of from 0.5 to 4 M, such as from 0.75 to 1.5 M, such as about 1 M in the first mixture.

[0068] In certain embodiments, the acidic supporting electrolyte may be an inorganic acid of an organic acid. The acidic supporting electrolyte may be present at a concentration of from 0.5 to 4 M, such as from 0.75 to 2 M, such as about 1.5 M in the second mixture. The inorganic acid may be selected from one or more of hydrochloric acid, nitric acid, and. more particularly, sulfuric acid. The organic acid may be selected from one or more of oxalic acid, and more particularly citric acid, and acetic acid.

[0069] Both electrodes in the redox-mediated metal-air fuel cell system, i.e., the cathode and the anode, can be a carbon, a metal, or a combination thereof. Preferably, these two electrodes have high surface area, with or without one or more catalysts, to facilitate the charge collection process. They can be made of a carbon, a metal, or a combination thereof. Examples of an electrode can be found in Skyllas-Kazacos, et al., Journal of The Electrochemical Society, 2011 , 158, R55-79, and Weber, et al., Journal of Applied Electrochemistry, 2011 , 41, 1137- 64. The discussion above in relation to the cathode may be particularly true for a cathode electrode situated in a cathode compartment that has an inlet and outlet suitable for the bubbling of a gas through the cathode compartment, such a compartment may be suitable for the use of a liquid catholyte.

[0070] The ion-selective membrane when mentioned herein may be an electro-active charge balancing ion conducting membrane (e.g. a proton, potassium, lithium or sodium ion conducting membrane). The ion-selective membrane prevents cross-diffusion of the redox mediator and allows for movement of electro-active charge balancing ions (e.g. protons, potassium, lithium ions, sodium ions, magnesium ions, aluminium ions, copper ions, or a combination thereof). For example, the ion-selective membrane may be a Nation™ membrane, a lithium phosphorus oxynitride glass, a lithium thiophosphate glass, sodium phosphorus oxynitride glass, a sodium thiophosphate glass, a NASICON-type lithium conducting glass ceramic, a NASICON-type sodium conducting glass ceramic, a Garnet-type lithium or sodium conducting glass ceramic, a ceramic nanofiltration membrane, a lithium or sodium ionexchange membrane, or suitable combinations thereof.

[0071] As disclosed herein, the term “load device” refers to any suitable electrical component that is capable of harvesting electrical energy generated during the methods disclosed herein.

[0072] All of the features disclosed in this specification may be combined in any combination. Each feature disclosed in this specification may be replaced by an alternative feature serving the same, equivalent, or similar purpose. Thus, unless expressly stated otherwise, each feature disclosed is only an example of a generic series of equivalent or similar features.

[0073] From the above description, one skilled in the art can easily ascertain the essential characteristics of the present invention, and without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions. Thus, other embodiments are also within the claims.

[0074] Hereinafter, embodiments of the invention are illustrated in more detail with reference to the following examples. However, the present disclosure is not limited thereto. Furthermore, what is not described in this disclosure may be sufficiently understood by those who have knowledge in this field and will not be illustrated herein.

[0075] EXAMPLES Materials and Methods

[0076] LiFePC>4 (LFP) and LiNixMnyCozO2 (NMC) standard samples were purchased from Beyond Battery Pte Ltd. UC0O2 (LCO) standard sample, and lithium acetate dihydrate (98.0%) were purchased from Sigma Aldrich. Li4Fe(CN)e was purchased from VIVA Medsciences.

[0077] Cyclic voltammetry (CV) measurements were carried out with an Autolab electrochemical workstation (Metrohm, PSTA30). A three-electrode cell was used to test the CV of the solid active materials and the soluble redox molecules, for which Pt plate and Ag / AgCI were used as the counter and reference electrode, respectively.

[0078] UV-Vis measurements were conducted using Shimadzu UV-27001 UV spectrophotometer. FTIR measurement was performed in a PerkinElmer Frontier MIR / FIR system with the attenuated total reflection (ATR) mode. XRD measurements were performed with a Powder XRD Diffractometer System (Bruker D8, Cu Ka radiation). ICP-OES measurement was performed via a Perkin Elmer Avio 500 Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES).

[0079] Example 1: Method of recovering metals from spent Li-ion battery materials via a flow cell involving redox-active molecules (RAMs) (Process 1)

[0080] FIG. 1 is a schematic illustration of a method of recovering metals from spent Li-ion battery materials via a flow cell according to an embodiment of the present disclosure. The method utilizes two redox-active molecules (RAMs) to selectively leach spent battery materials, exemplified by LiCoO2 (LCO) and LiFePO4 (LFP) in separate tanks. The steps are set out below.

[0081] In tank I, a first redox-active molecule (RAM1) having a redox potential higher than LFP (e.g., Li4Fe(CN)e) is dissolved in water and a supporting electrolyte (e.g., lithium acetate) and mixed with LFP. In tank II, a second redox-active molecule (RAM2) having a redox potential lower than LCO (e.g., benzoquinone disulfonic acid) is dissolved in an acidic solution (e.g., H2SO4) and mixed with LCO.

[0082] Both RAM1 and RAM2 undergo a chemical reaction with LCO and LFP respectively, during which the two spent battery materials are leached and meanwhile, charges are stored in the RAMs. The reacted RAM1 is filtered and pumped into tank III while the reacted RAM2 is filtered and pumped into tank IV. When the reacted RAMs are circulated into the flow cell, charges are released to produce electricity, and the electrical energy is harvested by the load connected. With the above steps, LCO is eventually decomposed into Li+and Co2+and LFP is leached into Li+and FePC (FP).

[0083] Results and Discussion

[0084] With LCO and LFP active materials as an example, the experimental results prove the feasibility of Process 1.

[0085] Here, Li4Fe(CN)e (Li-4) is used as RAMi and benzoquinone disulfonic acid (BQDS) is used as RAM2. From the CV results (FIG. 2a), the redox potential of RAM1 is 0.47 V vs. SHE, which is 70 mV higher than that of LFP (0.40 V vs. SHE); while the redox potential of RAM2 is 0.85 V vs. SHE, which is around 220 mV lower than that of LCO (1 .07 V vs. SHE). During operation, LFP was added into tank I containing 0.4 M Li4 and 1 M lithium acetate, while LCO was added into tank II containing 0.1 M BQDS and 1.5 M H2SO4. After the reactions, solutions from tank I and II are pumped to tank III and IV respectively for discharging. As shown in FIG. 2b, the cell could discharge at around 210 mV most of the time with a solid material utilization of around 80% in terms of the discharge capacity. From the XRD results in FIG. 2c and FIG. 2d, the residue in tank I was the LFP leaching product FP, and there was no LCO left in the residue in tank II. ICP-OES results showed the leaching efficiency of lithium and cobalt were more than 99.0%.

[0086] Example 2: Method of recovering metals from spent Li-ion battery materials via a semisolid flow cell (Process 2)

[0087] FIG. 3 is a schematic illustration of a method of recovering metals from spent Li-ion battery materials according to another embodiment of the present disclosure. The method utilizes a semi-solid flow cell setup to leach spent battery materials, exemplified by LCO and LFP at separate tanks. The steps are set out below.

[0088] In tank I, LFP powder is flowing together with the solution circulating between the tank and the flow cell in the center. In tank II, LCO powder is flowing together with the acidic solution circulating between the tank and the flow cell in the center.

[0089] When both the LCO and LFP powders are in contact with the electrode in the respective compartment of the flow cell, LCO is reduced while LFP is oxidized. Electricity is then produced and delivered to the load. After all charges are released, LCO is decomposed into Li+and Co2+and LFP is leached into Li+and FP. A cation-exchange membrane or porous separator permeable to Li+can be used to separate the two electrode compartments.

[0090] Results and Discussion

[0091] With LCO and LFP active materials as an example, the experimental results prove the feasibility of the Process 2 using a cation-exchange membrane as the separator.

[0092] During operation, LFP powder was made into slurry with carbon black in 1 M lithium acetate solution and added into tank I, which flowed into negative electrode compartment in the cell while LCO was made into slurry with carbon black in 1.5 M H2SO4 solution and added into tank II, which flowed into positive electrode compartment in the cell. As shown in FIG. 4, the cell could discharge at around 350 mV with a solid material utilization of 22.1% in terms of the discharge capacity. ICP-OES results showed the leaching efficiencies of cobalt and lithium were 47.6 % and 71.9%, respectively.

[0093] In summary, there is provided a leaching process of spent LiFePO4 and UCOO2 (or LiNixMnyCozO2 (NMC)) materials based on a flow cell setup according to an embodiment of the invention. Valuable metal ions can be leached and the waste energy in the spent battery materials can concurrently be harnessed. This process minimizes / eliminates the consumption of chemical and compensates for the energy consumed. There is also provided a flow cell setup that leaches the valuable metal ions from spent LiFePCU and LiCoO2 / NCM materials and simultaneously harness waste energy according to another embodiment of the invention.

Claims

CLAIMS1. A method of recovering one or more metals from at least two active materials obtained from a lithium or sodium ion battery, respectively, the method comprising:(a) providing a first active material and a second active material, each of the first and second active materials comprising lithium or sodium ions;(b) adding: the first active material to a first redox-active molecule solution that comprises a first solvent and an uncharged first redox-active molecule to form a first redox solution comprising lithium or sodium ions and a charged first redox-active molecule in a first tank, and the second active material to a second redox-active molecule solution that comprises a second solvent and a second redox-active molecule to form a second redox solution comprising lithium or sodium ions and a charged second redox-active molecule in a second tank, wherein the first and second active materials either both comprise lithium ions or both comprise sodium ions;(c) moving the first and second redox solutions from the first and second tanks to a redox flow cell, comprising: a first electrode compartment having a first electrode; a second electrode compartment having a second electrode; a cation exchange membrane that separates the first and second electrode compartments from one another; and a load device, where the charged first and second redox-active molecules interact via the cation exchange membrane to provide the uncharged first and second redox-active molecules, respectively and to generate electricity, which is harvested by the load device;(d) moving the first and second redox solution comprising uncharged first and second redox-active molecules, respectively, back to the first and second tanks, respectively, to provide first and second redox solutions comprising charged first and second redox-active molecules, respectively; and(e) repeating steps (c) and (d) until one or both of the first and second active materials are consumed, wherein: the first redox-active molecule has a redox potential higher than the first active material, but lower than the second redox-active molecule; the second redox-active molecule has a redox potential lower than the second active material; the first solvent comprises water and a supporting electrolyte; and the second solvent comprises water and an acidic supporting electrolyte.

2. The method according to Claim 1, wherein in step (c) of Claim 1, the step of moving the first and second redox solutions from the first and second tank to a redox flow cell comprises passing the respective first and second redox solutions through a respective filtration means or apparatus that prevents solid matter entering the redox flow cell.

3. The method according to Claim 1 or Claim 2, wherein the first and second active material is still attached to an electrode of a dismantled sodium- or lithium-ion battery or is provided free from the electrode.

4. The method according to any one of the preceding claims, wherein one or both of the following apply: the first redox-active molecule has a redox potential higher than the first active material of from 20 to 500 mV, such as from 40 to 250 mV, such as from 50 to 100 mV, such as about 70 mV; and the second redox-active molecule has a redox potential lower than the second active material of from 50 to 500 mV, such as from 80 to 300 mV, such as from 100 to 250 mV, such as about 220 mV, where the redox potentials of the first active material, the second active material, the first redox-active molecule and the second redox-active molecule are measured versus a standard hydrogen electrode.

5. The method according to any one of the preceding claims, wherein the first active material is selected from one or more of NaFePC , LixFePC (where 0 < x < 1) and LixMnyFezPO4, (where 0 < x, y, z < 1), such as LiFePC , and provided that the active material only contains one of lithium ions or sodium ions.

6. The method according to any one of the preceding claims, wherein the second active material is selected from one or more of NaxCoO2, more particularly, LiNixCoyMnzO2 (NCM, where 0 < x,y,z < 1), LixCoO2 (where 0 < x < 1), LiNixCoyAlzO2 (NCA, where x > 0.8, z < 0.05 and x + y + z = 1), LixM^C (where 0 < x < 1), LixNio.5Mn1.5O4 (where 0 < x < 1), such as LiCoO2, and provided that the active material only contains one of lithium ions or sodium ions.

7. The method according to any one of the preceding claims, wherein: when the first active material comprises lithium ions, then the first redox-active molecule is selected from one or more of the group consisting of a ferricyanide (Li3Fe(CN)a), a ferrocyanide (Li4Fe(CN)s), ferrocene (CioHioFe) and derivatives thereof, a quinone and derivatives thereof, and an iodide (Lil); orwhen the first active material comprises sodium ions, then the first redox-active molecule is selected from one or more of the group consisting of a ferricyanide (Na3Fe(CN)s), a ferrocyanide (Na4Fe(CN)e), ferrocene (CioHioFe) and derivatives thereof, a quinone and derivatives thereof, and an iodide (Nal).

8. The method according to any one of the preceding claims, wherein when the first active material comprises lithium ions, then the first redox-active molecule is a ferrocyanide (M4Fe(CN)e), such as Li4Fe(CN)e.

9. The method according to any one of the preceding claims, wherein one or more of the following apply: the total concentration of the first redox-active molecule present in the first solvent is from 0.05 M to 1 .5 M, such as about 0.4 M; the neutral supporting electrolyte is one or more of lithium acetate, lithium dihydrogen phosphate and lithium sulfate; and the supporting electrolyte is present at a concentration of from 0.5 to 4 M, such as from 0.75 to 1.5 M, such as about 1 M in the first redox-active molecule solution.

10. The method according to any one of the preceding claims, wherein the second redoxactive molecule is selected from one or more of the group consisting of benzoquinone disulfonic acid, hydroquinone sulfonic acid and, when the second active material comprises lithium ions, lithium bromide.11 . The method according to any one of the preceding claims, wherein the second redoxactive molecule is benzoquinone disulfonic acid.

12. The method according to any one of the preceding claims, wherein one or more of the following apply: the total concentration of the second redox-active molecule present in the second solvent is from 0.05 M to 1.5 M, such as from 0.75 to 0.5 M, such as about 0.1 M; the acidic supporting electrolyte is an inorganic acid or an organic acid; and the acidic supporting electrolyte is present at a concentration of from 0.5 to 4 M, such as from 0.75 to 2 M, such as about 1.5 M in the second redox-active molecule solution.

13. The method according to Claim 12, wherein: the inorganic acid is selected from one or more of hydrochloric acid, nitric acid, and. more particularly, sulfuric acid;the organic acid is selected from one or more of citric acid, acetic acid and oxalic acid.

14. A method of recovering one or more metals from at least two active materials obtained from a lithium or sodium ion battery, respectively, the method comprising:(a) providing a first active material and a second active material, each of the first and second active materials comprising lithium or sodium ions, where the first and second active materials either both comprise lithium ions or both comprise sodium ions;(b) adding: the first active material to a first solvent in a first tank to provide a first mixture, and the second active material to a second solvent in a second tank to provide a second mixture;(c) moving the first and second mixtures from the first and second tanks to a redox flow cell and returning the first and second mixtures to the first and second tanks, respectively, the redox flow cell comprising: a first electrode compartment having a first electrode; a second electrode compartment having a second electrode; a cation exchange membrane or a porous separator membrane that separates the first and second electrode compartments from one another; and a load device, where the first and second mixtures interact via the cation exchange or porous separator membrane to provide one or more species of metal ions and to generate electricity, which is harvested by the load device;(d) repeating step (c) until one or both of the first and second active materials are consumed, wherein: the first solvent comprises water and a supporting electrolyte; and the second solvent comprises water and an acidic supporting electrolyte.

15. The method of Claim 14, wherein the first and second active materials are provided in a particulate form and particles of the first and second active materials are allowed to circulate from the first and second tanks into the first and second electrode compartments, respectively.

16. The method according to Claims 14 or Claim 15, wherein the first active material is selected from one or more of NaFePO4, LixFePCu (where 0 < x < 1) and LixMnyFezPO4, (where 0 < x, y, z < 1), such as LiFePC , and provided that the active material only contains one of lithium ions or sodium ions.

17. The method according to any one of Claims 14 to 16, wherein the second active material is selected from one or more of NaCoCk, more particularly, LiNixCoyMnzO2 (NCM, where 0 < x,y,z < 1), LixCoO2 (where 0 < x < 1), LiNixCoyAlzO2 (NCA, where x > 0.8, z < 0.05 and x + y + z = 1), LLMnzC (where 0 < x < 1), LixNio5Mn1.5O4 (where 0 < x < 1), such as LiCoO2, and provided that the active material only contains one of lithium ions or sodium ions.

18. The method according to any one of Claims 14 to 17, wherein one or both of the following apply: the neutral supporting electrolyte is one or more of lithium acetate, lithium dihydrogen phosphate and lithium sulfate; and the supporting electrolyte is present at a concentration of from 0.5 to 4 M, such as from 0.75 to 1.5 M, such as about 1 M in the first mixture.

19. The method according to any one of Claims 14 to 18, wherein one or both of the following apply: the acidic supporting electrolyte is an inorganic acid of an organic acid; and the acidic supporting electrolyte is present at a concentration of from 0.5 to 4 M, such as from 0.75 to 2 M, such as about 1.5 M in the second mixture.

20. The method according to Claim 19, wherein: the inorganic acid is selected from one or more of hydrochloric acid, nitric acid, and. more particularly, sulfuric acid; the organic acid is selected from one or more of citric acid, acetic acid and oxalic acid.

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