Recycling method of waste battery material

Abstract

Disclosed herein is a process for the recovery of waste battery material, the process comprising the steps of: (a) providing a first reaction chamber fluidly connected to the cathode side of an electrolytic cell, (b) adding LiOH in a second reaction chamber to precipitate Co2 + to provide a filtered alkaline electrolyte, when Co2 + is substantially or completely removed from the filtered alkaline electrolyte by the precipitation, and (c) recovering the waste battery material from the filtered alkaline electrolyte. And (c) in an initial state, the reaction chamber contains FePO4 and accepts the filtered alkaline electrolyte from the second reaction chamber, the reaction cycle continuing until Li + ions are substantially or completely removed from the electrolyte. Also disclosed herein are electrolysis devices including an electrolysis cell, first to third cathode cells, and an anode cell, and electrolysis devices including a first electrolysis cell and a second electrolysis cell.

Description

Technical Field

[0001] The present invention discloses a high-throughput electrolyte flow cell system that continuously decomposes spent lithium-ion battery (LIB) materials into valuable chemicals under ambient conditions without consuming additional chemicals. It utilizes two mainstream LIB materials - LiFePO4 and LiCoO2 (or LiNi x Mn y Co z O2) complementary oxidative leaching reaction and reductive leaching reaction, thereby destructively minimizing secondary pollution, CO2 emissions and energy consumption. Background Art

[0002] The listing or discussion of a prior-published document in this specification should not necessarily be taken as an admission that the document is part of the state of the art or is common general knowledge.

[0003] LIB electrode materials, such as lithium cobalt oxide (LCO), lithium iron phosphate (LiFePO4, LFP), lithium manganese oxide (LiMnO2, LMO), and lithium nickel manganese cobalt oxide (LiNi x MnCo 1-x O2, NMC) and lithium nickel cobalt alumina (LiNiCoAlO2, NCA) as well as many other ternary lithium-ion batteries will face a significant increase in production, which will not only lead to the depletion of natural resources, but also lead to environmental problems related to mining and mineral processing activities, such as land and water pollution, ecosystem destruction and greenhouse gas emissions. In recent years, with the increasing awareness of environmental protection and the demand for electrode materials, the recycling of lithium-ion battery materials has also become a research hotspot. Although physical, chemical and biological methods have achieved the recovery of metal ions from electrode materials of spent lithium-ion batteries, they all cost a lot of chemical reagents and the amount of secondary pollutants produced does not meet the global environmental pollution emission reduction targets.

[0004] Since lithium cobalt oxide (LiCoCO2, LCO) was first used as a commercial cathode material by Sony in 1991, the demand for LiCoO2 has increased with the use of more and more portable electronic devices, which has led to an increasing amount of LiCoO2 discarded along with the flow of its waste batteries. In addition, the price of cobalt in discarded lithium cobalt oxide batteries is more expensive than lithium. The low abundance and uneven distribution of limited cobalt resources in natural ores have caused the manufacturing cost of lithium cobalt oxide batteries to continue to rise. Another serious problem is the toxicity of cobalt, which can easily cause environmental pollution. Therefore, whether from an environmental or economic perspective, recycling discarded lithium cobalt oxide batteries is a strategy that kills two birds with one stone.

[0005] Pyrometallurgy, hydrometallurgy and biometallurgy are the most studied LCO recovery strategies, all of which have achieved good recovery efficiency. Pyrometallurgy requires high temperature operation, which is bound to consume a lot of energy and produce some industrial waste gas; directly repairing waste batteries by this method requires additional consumption of a large amount of chemicals, and the reagents used are difficult to recover. Hydrometallurgy has the advantages of high metal ion leaching rate, relatively mild reaction, and high recovery purity. It has also become the most commonly used method in industrial recovery. However, more inorganic acids (such as strong corrosive acids such as sulfuric acid, hydrochloric acid, nitric acid, etc.) or organic acids (such as acetic acid, citric acid, ascorbic acid and oxalic acid, etc.) are required in the leaching process. In many cases, in addition to ascorbic acid and oxalic acid, additional reducing agents (such as hydrogen peroxide and other reducing agents) are also required. At the same time, a large amount of toxic gas emissions and excessive acid and alkali consumption, poor metal selectivity and equipment corrosion have gradually emerged and restricted the promotion and development of this method. Although biometallurgy is an environmentally friendly technology, the long reaction time is not conducive to the large-scale industrial recovery of waste lithium-ion batteries.

[0006] Although the discarded lithium cobalt oxide electrode material can be partially dissolved under acidic conditions, the trivalent cobalt ions Co(III) in LCO need to be reduced to divalent Co(II) soluble ions that can be completely dissolved, so this process requires the consumption of a large amount of reducing agents, such as H2O2. The slow leaching reaction rate and the hydrophobicity of the binder and conductive agent in the electrode material lead to incomplete leaching, which often needs to be carried out at high temperatures.

[0007] Therefore, from the perspective of sustainable development and green chemistry, it is crucial to develop sustainable closed-loop recycling technology for waste cobalt oxide lithium batteries. Summary of the invention

[0008] Various aspects and embodiments of the invention are disclosed in the following numbered clauses.

[0009] 1. A method for recycling waste battery materials, the method comprising the following steps:

[0010] (a) providing a first reaction chamber connected to a cathode side fluid of an electrolyzer, the electrolyzer comprising a cathode chamber comprising a cathode, an anode chamber comprising an anode, and a cation exchange membrane separating the cathode chamber and the anode chamber from each other, wherein the anode side of the electrolyzer is configured to produce protons by an oxygen evolution reaction or a hydrogen oxidation reaction, wherein in an initial state, the first reaction chamber comprises:

[0011] Contains LiCoO2 and / or LiNi x Mn y Co z Solid waste battery materials of O2; and

[0012] an acidic electrolyte comprising a first redox mediator capable of being reduced at a cathode, and

[0013] and

[0014] During the first reduction cycle, the acidic electrolyte from the first reaction chamber is provided to the first cathode chamber to provide a reduced first redox mediator, and the acidic electrolyte is returned to the first reaction chamber, wherein the reduced redox mediator reacts with the solid spent battery material to produce soluble Li + 、Co 2+ And when Ni exists 2+ Ions and Mn 2+ ions, while the reduced first redox mediator is oxidized back to its original form and supplies protons from the anode compartment through the cation exchange membrane,

[0015] During the subsequent reduction cycle, the acidic electrolyte from the first reaction chamber contains the first redox mediator and Li + 、Co 2+ And when Ni exists 2+ Ions and Mn 2+ ion,

[0016] Subsequent reaction cycles continue until Li, Co and, if present, Ni and Mn have been dissolved from the solid spent battery material, thereby containing the first redox mediator and Li + 、Co 2+ and existence

[0017] When Ni 2+ Ions and Mn 2+ An ionic acidic electrolyte is supplied to the second reaction chamber;

[0018] (b) In the second reaction chamber, the acidic electrolyte contains the first redox mediator and Li + 、Co 2+ And when Ni exists 2+ Ions and Mn 2+ ions, adding LiOH to make Co 2+ And when Ni exists 2+ Ions and Mn 2+ ion precipitation, thereby providing a first redox mediator and Li + of filtered alkaline electrolyte, when Co 2+ And when Ni exists 2+ Ions and Mn 2+ When ions are substantially or completely removed from the filtered alkaline electrolyte by precipitation, the filtered alkaline electrolyte is supplied to a third reaction chamber;

[0019] (c) in an initial state, the reaction chamber contains FePO4 and receives filtered alkaline electrolyte from the second reaction chamber,

[0020] During the first reaction cycle, the filtered alkaline electrolyte is supplied from the third reaction chamber to the cathode chamber to provide a electrolyte containing the reduced first redox mediator and Li + ions, and the electrolyte is returned to the third reaction chamber, wherein the reduced redox mediator reacts with FePO4 to produce LiFePO4, the reduced first redox mediator is oxidized back to its original form and protons are supplied from the anode chamber through the cation exchange membrane,

[0021] During the subsequent reaction cycle, the electrolyte from the third reaction chamber contains the first redox mediator and a reduced concentration of Li + ion,

[0022] The subsequent reaction cycle continues until Li + The ions are substantially or completely removed from the electrolyte so that the electrolyte matches or substantially matches the acidic electrolyte of step (b), at which point the LiFePO4 and any residual FePO4 are collected.

[0023] 2. The method according to clause 1, further comprising the following steps:

[0024] (i) providing a fourth reaction chamber connected to the anode side fluid of an electrolyzer, the electrolyzer comprising an anode chamber comprising an anode, a cathode chamber comprising a cathode, and a cation exchange membrane separating the cathode chamber and the anode chamber from each other, wherein the cathode side of the electrolyzer is configured to generate hydrogen gas and hydroxide ions by a hydrogen evolution reaction, the cathode chamber is connected to the storage tank fluid, wherein in an initial state, the fourth reaction chamber comprises:

[0025] a fourth reaction chamber containing the LiFePO 4 and any residual FePO 4 collected from step (d) of clause 1, and an electrolyte comprising a second redox mediator capable of being oxidized at the anode; and

[0026] The storage tank includes water,

[0027] During the first reaction cycle, the electrolyte from the fourth reaction chamber is provided to the anode chamber to provide an oxidized second redox mediator, and the electrolyte is returned to the fourth reaction chamber, wherein the oxidized redox mediator reacts with LiFePO4 to provide FePO4 and Li + ion,

[0028] During the subsequent reaction cycle, the electrolyte containing the redox mediator and Li+ ions is

[0029] is supplied to the anode compartment, where:

[0030] converting the redox mediator into an oxidized redox mediator; and

[0031] At least some Li + The ions are transported through the cation exchange membrane into the cathode compartment and thence to the storage tank,

[0032] Subsequent reaction cycles continue until the LiFePO4 is substantially or completely consumed and the storage tank contains aqueous lithium hydroxide.

[0033] 3. A method according to clause 1 or clause 2, wherein the first redox mediator has a lower x Mn y Co z The redox potential of O2, optionally wherein the redox potential of the first redox mediator is less than 0.4 V relative to a standard hydrogen electrode (SHE), such as 0.05 to 0.39 V relative to SHE, such as about 0.23 V relative to SHE or about 0.31 V relative to SHE.

[0034] 4. The method according to clause 4, wherein the first redox mediator is one or both of Fe-SO3Li and AQDS-2NH4.

[0035] 5. The method according to any of the preceding clauses, wherein the concentration of the first redox mediator in the acidic electrolyte is 1 to 100 mM, such as 2 to 50 mM, such as about 40 mM or about 5 mM.

[0036] 6. A method according to any of the preceding clauses, wherein the acidic electrolyte is formed from water and an acidic compound, optionally wherein the concentration of the acidic compound is from 0.2M to 5M, such as about 0.4M to 3M, further optionally wherein the acidic compound is sulfuric acid or acetic acid.

[0037] 7. A method according to any one of clauses 2 to 6, wherein the second redox mediator is Li3[Fe(CN6).

[0038] 8. A method according to any of the preceding clauses, wherein the method is run as a closed loop.

[0039] 9. An electrolysis device comprising:

[0040] an electrolytic cell comprising a first cathode chamber comprising a cathode, a first anode chamber comprising an anode, and a cation exchange membrane separating the first cathode chamber and the first anode chamber from each other;

[0041] The first to third cathode tanks, wherein:

[0042] The first cathode cell is in fluid connection with at least the cathode chamber and the second cathode cell;

[0043] a second cathode cell fluidly connected to at least the first cathode cell and the third cathode cell and capable of receiving LiOH;

[0044] The third cathode channel is fluidly connected to at least the first cathode channel, the second cathode channel and the first cathode chamber; and

[0045] an anode cell fluidly connected to the first anode chamber, wherein:

[0046] Each of the first cathode cell and the third cathode cell may be independently selected to be in fluid connection with the cathode chamber at any given time;

[0047] The first cathode cell is configured to receive spent battery material and electrolyte and to supply the liquid to the second cathode cell;

[0048] The second cathode cell is configured to receive the liquid from the first cathode cell and to receive the LiOH in solid and / or liquid form and to supply the liquid to the third cathode cell; and

[0049] The third cathode cell is configured to receive liquid from the second cathode cell.

[0050] 10. An electrolysis device comprising:

[0051] a first electrolytic cell comprising a first cathode chamber comprising a cathode, a first anode chamber comprising an anode, and a cation exchange membrane separating the first cathode chamber and the first anode chamber from each other;

[0052] a second electrolytic cell comprising a second cathode chamber comprising a cathode, a second anode chamber comprising an anode, and a cation exchange membrane separating the first cathode chamber and the first anode chamber from each other;

[0053] a first anode cell in fluid communication with the first anode chamber;

[0054] a second anode cell in fluid communication with the second anode chamber;

[0055] a first cathode cell in fluid communication with the first cathode chamber;

[0056] a second cathode cell fluidly connected to the second cathode chamber;

[0057] A third cathode cell is fluidly connected to the first cathode cell and the second cathode cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 depicts (ab) a schematic diagram of the recovery process of spent lithium-ion battery (LIB) materials by complementary reductive leaching of LCO and oxidative leaching of LFP. The leaching of LCO is operated in a single electrolyzer configuration, and the leaching of Co 2+ and Li + The removal is carried out sequentially. CEM: cation exchange membrane.

[0059] Figure 2 Depicted are (a) a schematic diagram of the reductive redox-targeted strategy for spent LCO materials utilizing oxygen evolution reaction (OER) decomposition. (b) an energy diagram of the redox-mediated electrochemical cycle for reductive leaching of LCO and coupled OER.

[0060] Figure 3 depicts (a) cyclic voltammograms (CV) of AQDS-(NH4)2 in 3M acetic acid and LiCoO2 powder in 0.5M H2SO4 solution. (b) Linear sweep voltammetry (LSV) of 50mM AQDS-(NH4)2 on a double-layer electrode in the absence (i) and presence (ii) of LiCoO2. The inset shows the double-layer electrode structure. (c) LSV of AQDS-(NH4)2 solution after open circuit potential (OCP) test. The inset shows the OCP result. (d) At 50mA cm -2 Voltage curves for the reductive leaching of LCO in an electrolyte flow cell coordinated with the OER reaction in the counter electrode at a constant current of .

[0061] Figure 4 Described are (a) electrochemical characterization of Co3O4 / CeO2 (prepared with 10 at% Ce) catalyst on carbon paper electrode in 0.5 M H2SO4 solution CV curves with or without catalyst. (b) Powder X-ray diffraction (PXRD) pattern of Co3O4 / CeO2 sample grown on carbon paper substrate by annealing at 400°C for 2 hours.

[0062] Figure 5 The precipitation of C after adding LiOH is described. O X-ray diffraction (XRD) pattern and Fourier transform infrared spectrum (FT-IR) of (OH)2.

[0063] Figure 6 Depicted are (a) the CV of AQDS-(NH4)2 in 1M lithium acetate solution and the CV of FePO4 powder in 1M lithium acetate solution. (b) OCP of AQDS-(NH4)2 solution at different reaction durations with excess FePO4. (c) OCP of AQDS-(NH4)2 solution at 50 mA cm -2 At a constant current of , in an electrolyte flow cell coordinated with the OER reaction in the counter electrode, FePO 4 (FP) Reduction and removal of Li + (d) Compared with the original LiFePO4, the voltage curve of Li + XRD patterns of FePO4 powder before and after embedding.

[0064] Figure 7Depicted are the LSVs of 5 mM AQDS-(NH4)2 on a double-layer electrode in the absence (i) and presence (ii) of FePO4. The inset shows the double-layer electrode structure.

[0065] Figure 8 The concentration changes of BSP-Fc+ at different durations of reaction with excess FePO4 are described.

[0066] Fig. 9 The electrochemical insertion of Li + and FT-IR spectra of samples collected from the cell after electrochemical embedding of commercial LiFePO4.

[0067] Fig.10 Depicted are (a) the CV of Li3[Fe(CN)6] in 0.5M Li2SO4Li solution and the CV of LiFePO4 powder in 0.5M Li2SO4Li solution. (b) The CV of Li3[Fe(CN)6] in 0.5M Li2SO4Li solution at 50mA cm -1 At a constant current of , in an electrolyte flow cell coordinated with the hydrogen evolution reaction (HER) in the counter electrode, Li + Voltage curves for oxidative leaching from LiFePO4.

[0068] Fig.11 FTIR spectra of samples collected from the tank and commercially available LiOH·H2O are described.

[0069] Fig.12 Describes (a) at 10 mA cm -2 Voltage curves for the reduction leaching of LCO in an electrolyte flow cell coordinated with the OER reaction in the counter electrode at a constant current of (a) 10 mA cm -2 Voltage curves for the removal of lithium from the electrolyte after the removal of cobalt by FePO4 in the electrolyte flow cell coordinated with the OER reaction in the counter electrode at a constant current of 10 mA cm -2 Voltage curve of the oxidative leaching of LiFePO4 obtained from lithium insertion in the previous step in an electrolyte flow cell coordinated with the HER reaction in the counter electrode at a constant current of .

[0070] Fig.13 The results show that the kinetics of the reaction at 10 mA cm-1 are not sufficient for the presence of a catalyst. -2 At a constant current of , NMC (NMC811; LiNi 0.85 Mn 0.1 Co 0.1 Voltage curve of reduction leaching of O2).

[0071] Fig.14Reductive leaching of LCO and simultaneous removal of Co is described 2+ and Li + Flowchart of AEM: anion exchange membrane.

[0072] Fig.15 The CV curves of 5 mM Fc-SO3Li and AQDS-2NH4 in 50 mM H2SO4 solution in a glassy carbon electrode are described. The scan rate is 50 mV / s.

[0073] Fig.16 Describes the use of Fc-SO3 - Voltage curve of reduction leaching of LCO in the electrolyte flow cell of RM1. Current density is 50 mA / cm 2 .

[0074] Fig.17 The XRD pattern of the obtained Co(OH)2 precipitate is described.

[0075] Fig.18 Describes (a) the use of Fc-SO3 - Reduction of FePO4 and Li in the electrolyte flow cell of RM1 + Voltage curve of embedding. Current density is 50mA / cm 2 (b) The obtained LFP in Li + XRD pattern after embedding.

[0076] Fig.19 Describes (a) the use of [Fe(CN)6] 3- / 4- Voltage curve of oxidative leaching of LFP in the electrolyte flow cell of RM2. Current density is 50 mA / cm 2 (b) XRD pattern of FP obtained after lithium leaching. DETAILED DESCRIPTION

[0077] The present invention relates to a high throughput electrolyte flow cell system for continuously decomposing spent lithium ion battery (LIB) materials into valuable chemicals under ambient conditions without consuming additional chemicals. As such, the present invention relates to an electrolysis device and a method for recycling spent battery materials.

[0078] Therefore, in a first aspect of the present invention, there is provided an electrolysis device comprising:

[0079] an electrolytic cell comprising a first cathode chamber comprising a cathode, a first anode chamber comprising an anode, and a cation exchange membrane separating the first cathode chamber and the first anode chamber from each other;

[0080] The first to third cathode tanks, wherein:

[0081] The first cathode cell is in fluid connection with at least the cathode chamber and the second cathode cell;

[0082] a second cathode cell fluidly connected to at least the first cathode cell and the third cathode cell and capable of receiving LiOH;

[0083] A third cathode cell is fluidly connected to at least the first cathode cell, the second cathode cell, and the first cathode chamber; and

[0084] an anode cell fluidly connected to the first anode chamber, wherein:

[0085] Each of the first cathode cell and the second cathode cell may be independently selected to be in fluid connection with the cathode chamber at any given time;

[0086] The first cathode cell is configured to receive spent battery material and electrolyte and to supply the liquid to the second cathode cell;

[0087] The second cathode cell is configured to receive the liquid from the first cathode cell and to receive the LiOH in solid and / or liquid form and to supply the liquid to the third cathode cell; and

[0088] The third cathode cell is configured to receive liquid from the second cathode cell.

[0089] In a second aspect of the present invention, there is provided an electrolysis device comprising:

[0090] a first electrolytic cell comprising a first cathode chamber comprising a cathode, a first anode chamber comprising an anode, and a cation exchange membrane separating the first cathode chamber and the first anode chamber from each other;

[0091] a second electrolytic cell comprising a second cathode chamber comprising a cathode, a second anode chamber comprising an anode, and a cation exchange membrane separating the first cathode chamber and the first anode chamber from each other;

[0092] a first anode cell in fluid communication with the first anode chamber;

[0093] a second anode cell in fluid communication with the second anode chamber;

[0094] a first cathode cell in fluid communication with the first cathode chamber;

[0095] a second cathode cell fluidly connected to the second cathode chamber;

[0096] A third cathode cell is fluidly connected to the first cathode cell and the second cathode cell.

[0097] The reference numerals for the two above-mentioned aspects of the invention refer to those in Figure 1. For convenience, alternative arrangements of the device have the same reference numerals.

[0098] The first and second aspects of the invention may be used in combination to provide a closed loop method for recycling spent battery materials.

[0099] In the embodiments herein, the term "comprising" may be interpreted as requiring the features mentioned, but not limiting the presence of other features. Alternatively, the term "comprising" may also refer to situations in which only the listed components / features are intended to be present (e.g., the term "comprising" may be replaced by the phrase "consists of" or "consists essentially of". It is expressly contemplated that both broad and narrow interpretations may apply to all aspects and embodiments of the present invention. In other words, the term "comprising" and its synonyms may be replaced by the phrase "consists of" or "consists essentially of" or their synonyms, and vice versa.

[0100] The phrase "consisting essentially of" and its pseudonyms may be interpreted herein to refer to a material in which small amounts of 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.

[0101] As used herein, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a composition" includes mixtures of two or more such compositions, and reference to "a redox mediator" includes mixtures of two or more such redox mediators, etc.

[0102] Therefore, in a third aspect of the present invention, there is provided a method for recycling waste battery materials, the method comprising the following steps:

[0103] (a) providing a first reaction chamber connected to a cathode side fluid of an electrolyzer, the electrolyzer comprising a cathode chamber comprising a cathode, an anode chamber comprising an anode, and a cation exchange membrane separating the cathode chamber and the anode chamber from each other, wherein the anode side of the electrolyzer is configured to produce protons by an oxygen evolution reaction or a hydrogen oxidation reaction, wherein in an initial state, the first reaction chamber comprises:

[0104] Contains LiCoO2 and / or LiNi x Mn y Co z Solid waste battery materials of O2; and

[0105] an acidic electrolyte comprising a first redox mediator capable of being reduced at a cathode, and

[0106] and

[0107] During the first reduction cycle, the acidic electrolyte from the first reaction chamber is provided to the first cathode chamber to provide a reduced first redox mediator, and the acidic electrolyte is returned to the first reaction chamber, wherein the reduced redox mediator reacts with the solid spent battery material to produce soluble Li + 、Co 2+ And when Ni exists 2+ Ions and Mn 2+ ions, while the reduced first redox mediator is oxidized back to its original form and supplies protons from the anode compartment through the cation exchange membrane,

[0108] During the subsequent reduction cycle, the acidic electrolyte from the first reaction chamber contains the first redox mediator and Li + 、Co 2+ And when Ni exists 2+ Ions and Mn 2+ ion,

[0109] Subsequent reaction cycles continue until Li, Co and, if present, Ni and Mn have been dissolved from the solid spent battery material, thereby containing the first redox mediator and Li + 、Co 2+ and existence

[0110] When Ni 2+ Ions and Mn 2+ An ionic acidic electrolyte is supplied to the second reaction chamber;

[0111] (b) In the second reaction chamber, the acidic electrolyte contains the first redox mediator and Li + 、Co 2+ And when Ni exists 2+ Ions and Mn 2+ ions, adding LiOH to make Co 2+ And when Ni exists 2+ Ions and Mn 2+ ion precipitation, thereby providing a first redox mediator and Li + of filtered alkaline electrolyte, when Co 2+ And when Ni exists 2+ Ions and Mn 2+ When ions are substantially or completely removed from the filtered alkaline electrolyte by precipitation, the filtered alkaline electrolyte is supplied to a third reaction chamber;

[0112] (c) in an initial state, the reaction chamber contains FePO4 and receives filtered alkaline electrolyte from the second reaction chamber,

[0113] During the first reaction cycle, the filtered alkaline electrolyte is supplied from the third reaction chamber to the cathode chamber to provide a electrolyte containing the reduced first redox mediator and Li + ions, and the electrolyte is returned to the third reaction chamber, wherein the reduced redox mediator reacts with FePO4 to produce LiFePO4, the reduced first redox mediator is oxidized back to its original form and protons are supplied from the anode chamber through the cation exchange membrane,

[0114] During the subsequent reaction cycle, the electrolyte from the third reaction chamber contains the first redox mediator and a reduced concentration of Li + ion,

[0115] The subsequent reaction cycle continues until Li + The ions are substantially or completely removed from the electrolyte so that the electrolyte matches or substantially matches the acidic electrolyte of step (b), at which point the LiFePO4 and any residual FePO4 are collected.

[0116] As will be appreciated, the method disclosed above may utilize the apparatus of the first aspect of the invention. It will also be appreciated that the above method allows lithium (and other metals) to be recovered from the battery in a form that can be easily recovered. For example, in various embodiments of the invention, the method may further comprise the steps of:

[0117] (i) providing a fourth reaction chamber connected to the anode side fluid of an electrolyzer, the electrolyzer comprising an anode chamber comprising an anode, a cathode chamber comprising a cathode, and a cation exchange membrane separating the cathode chamber and the anode chamber from each other, wherein the cathode side of the electrolyzer is configured to generate hydrogen gas and hydroxide ions by a hydrogen evolution reaction, the cathode chamber is connected to the storage tank fluid, wherein in an initial state, the fourth reaction chamber comprises:

[0118] The fourth reaction chamber collects LiFePO4 and any residual FePO4 from step (d) above, and

[0119] an electrolyte comprising a second redox mediator capable of being oxidized at the anode; and

[0120] The storage tank includes water,

[0121] During the first reaction cycle, the electrolyte from the fourth reaction chamber is provided to the anode chamber to provide an oxidized second redox mediator, and the electrolyte is returned to the fourth reaction chamber, wherein the oxidized redox mediator reacts with LiFePO4 to provide FePO4 and Li + ion,

[0122] During the subsequent reaction cycle, the redox mediator and Li + An ionic electrolyte is supplied to the anode chamber, where:

[0123] The redox mediator is converted to an oxidized redox mediator; and at least some of the Li + The ions are transported through the cation exchange membrane into the cathode compartment and thence to the storage tank,

[0124] Subsequent reaction cycles continue until the LiFePO4 is substantially or completely consumed and the storage tank contains aqueous lithium hydroxide.

[0125] In an embodiment of the present invention, the first redox mediator may be any suitable material. For example, the first redox mediator may have a lower carbon content than LiCoO2 and / or LiNi x Mn y Co z O2 redox potential. In a specific embodiment of the present invention, the redox potential of the first redox mediator may be less than 0.4 V relative to the standard hydrogen electrode (SHE), for example, 0.05 to 0.39 V relative to SHE, for example, about 0.23 V relative to SHE or about 0.31 V relative to SHE. In a more specific embodiment of the present invention, the first redox mediator may be one or both of Fe-SO3Li and AQDS-2NH4.

[0126] The first redox mediator may be present in the acidic electrolyte at any suitable concentration. For example, the concentration of the first mediator in the acidic electrolyte may be 1 to 100 mM, such as 2 to 50 mM, such as about 40 mM or about 5 mM.

[0127] The acidic electrolyte can be formed by water and an acidic compound (for the avoidance of doubt, this can be more than one acidic compound). The acidic compound can be an organic acid or it can be an inorganic acid. In a particular embodiment of the invention, the acidic compound can be sulfuric acid and / or acetic acid. Any suitable concentration of the acidic compound can be used in the embodiments herein. For example, the concentration of the acidic compound can be 0.2M to 5M, such as about 0.4M to 3M.

[0128] The second redox mediator can be any suitable material capable of conducting the functions mentioned herein. For example, the first redox mediator can have a redox potential lower than that of LiFePO4. In a particular embodiment of the invention, the second redox mediator can be Li3[Fe(CN6).

[0129] As described herein, the methods described herein can be operated in a closed loop manner.

[0130] The methods and apparatus mentioned herein will now be described in more detail with reference to the accompanying drawings.

[0131] Figure 1a An electrolysis apparatus 100 is described that can be used to strip metals from spent lithium battery material and provide the metals in a form that can be easily removed from the apparatus for further processing when desired. Figure 1b Describes a method for obtaining Figure 1a The final product of the device is an electrolysis device 110 for obtaining a lithium hydroxide aqueous solution.

[0132] Figure 1a The electrolysis device 100 is a possible arrangement of components that can be used to obtain metals in a form suitable for further processing or use from waste lithium battery materials. The device includes an electrolytic cell 120, which includes a first cathode chamber 121 containing a cathode, a first anode chamber 122 containing an anode, and a cation exchange membrane 108 separating the first cathode chamber and the first anode chamber from each other. Attached to the electrolytic cell on the cathode chamber side are the first cathode cell 101, the second cathode cell 102, and the third cathode cell 103. When necessary, each of these cells can be fluidly connected to the electrolytic cell 120 and fluidly connected to each other. The fluid connection between the cell and the electrolytic cell can be controlled by more than one valve 150. Any suitable valve can be used herein. In specific embodiments that may be mentioned herein:

[0133] The first cathode cell 101 may be fluidly connected to the cathode chamber and the second cathode cell;

[0134] The second cathode cell 102 may be fluidly connected to the first cathode cell 101 and the third cathode cell 103 and may be capable of receiving LiOH;

[0135] The third cathode tank 103 can be connected to the first cathode tank 101, the second cathode tank 102 and the first cathode chamber 121 fluid. The first anode chamber 122 is connected to the anode tank 104 fluid. The device also includes suitable fluid connections, valves and pumps 107. The first cathode tank 101 and the third cathode tank 103 can be independently selected to be connected to the first cathode chamber 120 fluid at any given time. The first cathode tank is configured to receive waste battery materials and electrolyte and supply liquid to the second cathode tank. The second cathode tank is configured to receive liquid from the first cathode tank and receive LiOH in solid and / or liquid form, and supply liquid to the third cathode tank. The third cathode tank is configured to receive liquid from the second cathode tank. In use, the electrolysis device 100 will be connected to a power supply 109 by an anode and a cathode.

[0136] Figure 1b The electrolysis device 110 is intended to convert Figure 1aThe solid storage form of lithium obtained by the device and the lithium hydroxide aqueous solution are provided. Therefore, the device 110 has a cathode chamber 131 including a cathode, an anode chamber 132 including an anode, and a cation exchange membrane 108 separating the cathode chamber and the anode chamber from each other. Attached to the electrolytic cell on the cathode chamber side is a cathode cell 106, which is in fluid communication with the cathode chamber. Attached to the electrolytic cell on the anode chamber side is an anode cell 105, which is in fluid communication with the cathode chamber. The device also includes suitable fluid connections, valves and pumps 107. The device is configured to remove liquid from the anode cell in the anode cell. Figure 1a The device receives solid material and is configured to collect LiOH in the cathode cell. In use, the electrolysis device 100 will be connected to a power source 109 via the anode and cathode.

[0137] Figure 1a and Figure 1b The apparatus can be used as follows to recover lithium and other metals (if present) from spent battery materials. First, refer to Figure 1a .

[0138] Process 1: Reductive leaching of spent battery materials (eg using LiCoO2 (LCO)).

[0139] (1) The electrolytic cell 120 is fluidically connected to the cathode cell 101 and the anode cell 104 .

[0140] (2) The cathode cell 101 contains spent battery material (e.g., LCO), an acidic electrolyte, and a redox mediator 1 (RM1). The electrolyte (including RM1) is supplied to the cathode chamber 121, where RM1 is reduced to RM1 at the cathode. - .

[0141] (3) will include RM1 - The electrolyte is returned to the cathode tank 101. When RM1 - When contacting LCO, RM1 - is oxidized back to RM1 and LCO is reduced. Under acidic conditions (pH = 0-3), the reduced oxide material gradually dissolves into Li + Ions, Co2 + ion.

[0142] (4) The electrolyte containing RM1 is pumped back to the cathode chamber where it is reduced back to RM1 - for the next round of reaction.

[0143] (5) On the anode side, the oxygen evolution reaction (OER) may be used while water is supplied from the anode tank 104. The OER generates protons.

[0144] (6) The generated protons pass through the cation exchange membrane 108 and enter the cathode chamber 121. Therefore, the pH of the electrolyte will change over time as more protons are introduced from the anode chamber into the cathode chamber.

[0145] (7) The above steps are continued until LCO is completely dissolved, at which point the pH is <3.

[0146] (8) Remaining undissolved impurities are removed from the cathode cell 101.

[0147] Step 2: Removal of Co2 by precipitation +

[0148] (1) After step 1 is completed, the dissolved LCO is provided to the cathode cell 102 together with the electrolyte containing Li + 、Co2 + , RM1 and supporting electrolyte.

[0149] (2) In tank 102, LiOH is added, so that Co2 + Co(OH)2 is formed and precipitated. The precipitated Co(OH)2 can then be separated from the electrolyte. Note that when the pH of the solution is above 10, Co2 + Can be almost completely removed.

[0150] (3) The obtained current contains Li + The filtered electrolyte of RM1 flows into the cathode tank 103.

[0151] Step 3: Electrochemical removal of Li +

[0152] (1) The electrolytic cell 120 is fluidically connected to the cathode cell 103 and the anode cell 104 .

[0153] (2) FePO4 (FP) is pre-charged in the cathode cell 103.

[0154] (3) The filtered electrolyte from step 2 flows back into the cathode chamber 121 of the electrolytic cell 120, and RM1 is reduced to RM1 at the cathode. - .

[0155] (4) Contains Li + and RM1 - The electrolyte flows into the cathode tank 103, where RM1 - FP is reduced and itself is oxidized back to RM1. The reduction of FP involves Li + of intercalation to form LiFePO4 (LFP).

[0156] (5) The electrolyte containing RM1 is pumped back to the cathode chamber, where RM1 is reduced back to RM1 -for the next round of reaction.

[0157] (6) On the anode side, the oxygen evolution reaction (OER) may be employed while water is supplied from the anode tank 104. The OER generates protons.

[0158] (7) The generated protons pass through the cation exchange membrane 108 into the cathode chamber 121, thereby lowering the pH of the electrolyte (which is initially alkaline (eg, pH 10)) over time.

[0159] (8) The above steps are performed continuously to achieve Li + (LCOLi from step 1 + ions and LiOH from step 2 + ions) removal.

[0160] (9) At this time, the pH and composition of the electrolyte are restored to match (or substantially match) the pH and composition used in step 1 (1).

[0161] (10) The solid LFP can then be removed from the cathode cell 103.

[0162] Refer to Figure 1B.

[0163] Process 4: Li + Oxidative leaching and separation

[0164] (1) This step involves the electrolytic cell 130 that cooperates with the cathode cell 106 and the anode cell 105.

[0165] (2) The LFP obtained in step 3 is transferred to the anode tank 105 .

[0166] (3) On the anode side, the redox mediator 2 (RM2) in the anolyte is first oxidized to RM2 at the anode in the anode chamber 132. + .

[0167] (4) Including RM2 + The electrolyte flows into the anode tank 105, where RM2 + Oxidation of LFP and RM2 + The oxidation of LFP involves Li + Extraction of ions, thereby forming FP.

[0168] (5) Contains RM2 and Li + The electrolyte is pumped back to the anode chamber where RM2 is oxidized back to RM2 + for the next round of reaction.

[0169] (6) Li in the electrolyte +The ions are transported through the cation exchange membrane 108 to the cathode chamber 131 .

[0170] (7) On the cathode side, when water is supplied, a hydrogen evolution reaction (HER) occurs to produce H2 and OH - The concentration of LiOH in the electrolyte in the tank 105 gradually increases.

[0171] (8) These reactions are carried out continuously to achieve the Li + Complete (or almost complete) extraction of

[0172] (9) The FP obtained in tank 105 can be used again in step 3 to remove Li + In addition, part of the produced LiOH can be used in step 2 to remove Co2 + .

[0173] Utilizing the above complementary and closed-loop reactions, the entire cycle of LCO only requires the supply of water and electricity. Note that the OER reaction in electrolyzer 120 can be replaced by a hydrogen oxidation reaction (HOR) in the case of supplying H2 produced from electrolyzer 130. This will allow the process to operate without waste (except for impurities in the black mass of waste LCO, i.e., carbon black, binder, etc.), and power consumption can be further reduced. Finally, waste LCO is decomposed into battery-grade LiOH and Co(OH)2. Note that other metals used in lithium-ion batteries can be recovered together with Co as a precipitate in the above process 2.

[0174] Fig.14 An alternative arrangement of the apparatus that can be used from steps 1 to 3 above is described in FIG. In this apparatus, there are two separate electrolytic cells 120 and 140. Electrolytic cell 120 is intended to be fluidly connected to cathode cell 101 and anode cell 104. Electrolytic cell 140 is intended to be connected to cathode cell 103 and anode cell 145. As shown, cathode cell 102 in this apparatus is only fluidly connected to cathode cells 101 and 103. Due to the presence of valves and pumps, it will be understood that the same Figure 1a The apparatus is operated in a manner similar to that described in . In this case, one of the anode cell and the electrolytic cell (i.e., anode cell 104 and electrolytic cell 120 or anode cell 145 and electrolytic cell 140) is not used. However, all cells may be used and will now be discussed in more detail below.

[0175] Process 1: Reductive leaching of spent battery materials (eg using LiCoO2 (LCO)).

[0176] The process operates in the same manner as previously discussed, with the cathode cell 101 and the anode cell 104 being fluidly connected to the electrolytic cell 120 .

[0177] Step 2: Removal of Co2 by precipitation +

[0178] (1) After step 1 is completed, the dissolved LCO is mixed with the Li + 、Co2 + , RM1 and an electrolyte supporting the electrolyte are provided to the cathode cell 102 together.

[0179] (2) In tank 102, LiOH is added, so that Co2 + Co(OH)2 is formed and precipitated. The precipitated Co(OH)2 can then be separated from the electrolyte. Note that when the pH of the solution is above 10, Co2 + Can be almost completely removed.

[0180] (3) The obtained current contains Li + The filtered electrolyte of RM1 flows into the cathode tank 103.

[0181] Process 3: Li + Electrochemical removal of

[0182] The process operates in the same manner as previously discussed, with the cathode cell 103 and the anode cell 145 being fluidly connected to the electrolytic cell 140 .

[0183] As will be appreciated, the apparatus and process flow can facilitate the sequential operation of processes 1 to 3, thereby improving the efficiency and throughput of the system.

[0184] Then from Fig.14 The LFP obtained in step 3 can be subjected to step 4 (using Figure 1b apparatus) to provide LiOH.

[0185] Further details of the operation of the apparatus and methods can be found in the Examples section below.

[0186] The use of a redox mediator as a reducing agent to continuously leach spent LiCoO2 and NMC materials means that the reducing agent can be regenerated through an electrochemical process without the need to add additional chemicals to the system. When this is combined with the oxidation reaction used to leach the lithium, a complete closed-loop process is formed, meaning that all chemicals used in the process can be regenerated, with water as the only chemical consumable. This reduces the consumption of chemical reagents, thereby reducing the environmental impact of the process.

[0187] The process outlined herein allows for complete separation of different metal ions. As shown in the above embodiments and in the following examples, lithium ions and cobalt ions can be completely separated from each other to form high purity products.

[0188] As will be appreciated, the above process is agnostic as to whether the spent battery material (ie spent active material) is obtained from the cathode and / or anode. This is because the process can be used for both types of active materials, although cathode active materials may be preferred.

[0189] As will be appreciated, the above process involves the recovery of lithium from spent (reclaimed) batteries or from waste materials generated during the manufacturing process. Therefore, the above mentioned active materials may not function in the battery in their current form, so the lithium and other valuable elements need to be recovered for reuse.

[0190] The cation exchange membrane separates the cathode chamber from the anode chamber. It can be an electroactive ion conducting membrane (e.g., a proton or lithium ion conducting membrane). The cation exchange membrane prevents cross diffusion of redox mediators and allows the movement of electroactive ions (e.g., potassium ions, or more specifically, protons, lithium ions, sodium ions, magnesium ions, aluminum ions, silver ions, copper ions, protons, or a combination thereof; more specifically, the electroactive ions can be potassium ions, or more specifically, protons, lithium ions, sodium ions, magnesium ions, aluminum ions, copper ions, protons, or a combination thereof). For example, the cation exchange membrane can be lithium phosphorus oxynitride glass, lithium thiophosphate glass, sodium phosphorus oxynitride glass, sodium thiophosphate glass, NASICON-type lithium conducting glass ceramics, NASICON-type sodium conducting glass ceramics, garnet-type lithium or sodium conducting glass ceramics, ceramic nanofiltration membranes, lithium or sodium ion exchange membranes, or suitable combinations thereof.

[0191] The electrodes in the device, i.e. the cathode and the anode, can be carbon, metal or a combination thereof. Preferably, the two electrodes have a high surface area, with or without one or more catalysts to facilitate the charge collection process. They can be made of carbon, metal or a combination thereof. Examples of electrodes can be found in Skyllas-Kazacos et al., Journal of The Electrochemical Society, 158, R55-79 (2011) and Weber et al., Journal of Applied Electrochemistry, 41, 1137-64 (2011).

[0192] The cathode active material may be from a depleted (retired) battery or from a manufacturing process for making such a battery. Any form of cathode active material may be used. For example, the cathode active material may still be attached to the cathode electrode of a dismantled lithium-ion battery or sodium-ion battery, or may be provided without being connected to the cathode electrode.

[0193] Examples of cathode active materials include, but are not limited to, LiCoO2 and / or LiNi x Mn y Coz O2, and combinations thereof.

[0194] The redox mediator refers to a compound present in (eg, dissolved in) a solvent placed in the same tank (ie, the first tank) as an active material, which acts as a molecular shuttle to transport lithium to an electrode in a flow cell to which the tank is connected.

[0195] The process of recovering the anode active material is similar to the process of recovering the cathode active material described above.

[0196] Although the procedures described herein use only cathode active materials or anode active materials alone, it will be understood that the same procedures as described above can be performed for combinations of cathode active materials and anode active materials.

[0197] Further aspects and embodiments of the invention will now be discussed by reference to the following non-limiting examples.

[0198] Example

[0199] Material

[0200] Unless otherwise stated, all chemicals and reagents were purchased from commercial suppliers and used without any purification. Anthraquinone-2,7-disulfonic acid sodium salt was purchased from Zhengzhou Alfa Chemical Co., Ltd. Battery-grade LiFePO4 powder was purchased from Li-cell Co. Reagent-grade LiOH.H2O (99.5%), K3Fe(CN)6 (99.0%), Fe4[Fe(CN)6]3 (99.3%), and LiCoO2 were purchased from Sigma Aldrich without further purification. Nafion 212 membrane was purchased from Dupont and used directly. Co(NO3)2, Ce(NO3)3, AlCl3, CH2Cl2, NaBH4, diethylene glycol dimethyl ether, EtOH, amberlite cation exchange resin, polyvinylidene fluoride (PVDF), N-methyl-2-pyrrolidone (NMP), and ammonium hydroxide were purchased from Sigma Aldrich. NMC811 was purchased from Beyond Battery Pte Ltd.

[0201] All reactions were performed in flame-dried glassware under nitrogen atmosphere.

[0202] Analytical techniques

[0203] Nuclear Magnetic Resonance (NMR) Spectroscopy

[0204] Recorded on a Bruker 500MHz spectrometer1 H spectra. NMR spectra were recorded in solutions of deuterated dimethyl sulfoxide (DMSO-d6) with residual DMSO (for 1 H-NMR, 2.50 ppm) as the internal standard, and deuterium oxide (D2O) and D2O (for 1 H-NMR, 4.79 ppm) as an internal standard. The data are expressed as chemical shifts (δ) per parts per million.

[0205] XRD

[0206] XRD measurements were performed using a powder XRD diffractometer system (Bruker D8, Cu Kα radiation).

[0207] Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES)

[0208] ICP-OES was performed in the Elemental Analysis Laboratory of the Department of Chemistry, NUS.

[0209] FT-IR spectroscopy

[0210] FTIR measurements were performed using a PerkinElmer Frontier MIR / FIR system with attenuated total reflectance (ATR) mode to confirm the structure of the collected Co(OH)2 and LiOH powders. -1 At the resolution of 4000 to 400 cm for Co(OH)2 -1 and for LiOH from 4000 to 500 cm -1 FTIR spectra were collected separately.

[0211] General procedure for the synthesis of anthraquinone-2,7-disulfonic acid diammonium salt

[0212] Anthraquinone-2,7-disulfonic acid diammonium salt was synthesized using the following method. AQDS-2Na was first converted to AQDS acid by dissolving it in deionized water and rinsed on a cation exchange column with Amberlite cation exchange resin (IR-120 hydrogen form). After removing water with a rotary evaporator and drying in a vacuum oven at 60°C for 24h, a yellow AQDS solid acid was obtained. The AQDS acid was then dissolved in deionized water and cooled by an ice bath. 30% ammonium hydroxide was added to convert the acid into an ammonium salt. After removing water with a rotary evaporator, the wet solid residue was dried in a vacuum oven at 60°C for 24h. The final product AQDS-2NH4 was collected as a dark brown solid.

[0213] Example 1.1, Synthesis of 1'-bis(propylsulfite lithium)ferrocene (BSP-Fc)

[0214]

[0215] 1,1'-bis-(propylsulfite lithium) ferrocene is obtained by ion exchange with 1,1'-bis(propylsulfite sodium) ferrocene (Energy Storage Mater, J. Yu et al., 2020, 29, 216-222). 1,1'-bis(propylsulfite sodium) ferrocene (2 g, 4.22 mmol) was dissolved in deionized water (5 mL) and rinsed on a cation exchange column with Amberlite cation exchange resin (IR-120 hydrogen form). The resulting solution was cooled by an ice bath. Then, LiOH.H2O (0.18 g, 4.28 mmol) was added to convert the acid into a lithium salt. After removing water by a rotary evaporator, the precipitated solid was dried in a vacuum oven.

[0216] 1 H NMR (500MHz, DMSO-d6): δ4.21-4.18(m,8H), 2.95-2.92(m,4H), 2.46(t,4H,J=4.6Hz), 1.97-1.91(m,4H).

[0217] Example 2. Chemical and electrochemical synthesis of Li4[Fe(CN)6] and Li3[Fe(CN)6]

[0218] Li4[Fe(CN)6] was synthesized by immersing 5.0 g of Fe4[Fe(CN)6] powder in 60 mL of 1 M LiOH.H2O (3.08 g, 73.3 mmol) solution with deionized water as solvent. After reacting at room temperature for 10 h, a light yellow Li4[Fe(CN)6] solution (as shown in formula (1)) was obtained after removing the brown Fe(OH)3 precipitate by filtration. Then, the solvent was removed under reduced pressure, and the obtained crude product was washed with ethanol. The filtered solid was heated in a vacuum oven at 60°C for 24 h. Light yellow crystalline particles were obtained. Li3Fe(CN)6 solution was prepared by electrolyzing Li4Fe(CN)6 solution. A hydrogen evolution reaction (HER) occurred on the counter electrode (cathode) using a 0.5 M Li2SO4 solution as the supporting electrolyte. Carbon felt (5 cm 2 ) are used as anode and cathode electrodes in flow battery cells.

[0219] Fe3[Fe(CN)6]4+12 LiOH→Li4[Fe(CN)6]+3 Fe(OH)3(s) (1)

[0220] Example 3. Synthesis of OER catalyst

[0221] OER catalysts were synthesized according to references (Huang, J. et al. Nat. Commun. 2021, 12, 3036). First, Ce(OH)3-doped Co(OH)2 was synthesized by electroplating with 0.09 mol Co(NO3)2 and 0.01 mol Ce(NO3)3 as electrolytes. During the electroplating, a constant potential of -1.0 V relative to Ag / AgCl was applied to the substrate for 10 min with Pt mesh as the counter electrode in the case of carbon paper (the original carbon paper substrate (Fuel Cell Store, Sigracet 39AA) was Teflon-coated; before use, it was first annealed in air at 400 ° C for 10 h to make the surface hydrophilic.). After electroplating, the obtained metal hydroxide precursor was dried in a vacuum oven at 60 ° C and then annealed in air at 400 ° C for 2 h in a muffle furnace to convert it into an oxide.

[0222] Example 4. Closed-loop waste LCO battery recycling system (path 1)

[0223] According to the mechanism of redox targeting, when the redox potential of the mediator molecule and the solid active material are different, the potential difference provides a driving force for the reaction between them. When the potential of the mediator molecule is higher than that of the solid active material, the mediator molecule is reduced, then pumped to the anode to charge and return to the initial state, and then enters the next cycle. When the mediator has a lower potential, a reversal occurs, which can continuously reduce the solid material. The mediator as a charge carrier connects the electrode to the solid active material, thereby realizing the continuous transfer of electrons from the electrode to the uncontacted active material. Previous studies have achieved effective recovery of lithium ions through oxidation leaching by redox targeting reactions of waste lithium iron phosphate (LFP) batteries (J. Yu et al., Energy Environ. Sci. 2019, 12, 2672-2677). However, the high redox potential of LCO (up to 1V higher) makes the oxidation leaching method for LFP almost impossible, because the redox mediator is difficult to survive and may induce water decomposition. Therefore, it is proposed to change from oxidation leaching to reduction leaching as an effective and feasible means for recovering oxide materials.

[0224] Here, we propose a new high-throughput electrolyte flow cell system to continuously decompose spent battery materials into valuable chemicals under ambient conditions, combined with a chemical process to separate and recover cobalt and lithium ions with high yield and purity without consuming additional chemicals.

[0225] A closed-loop spent LCO battery recycling system based on integrated redox-targeted electrochemical and chemical processes is shown in FIG1 . As depicted in FIG1 , the apparatus 100 includes a tank I 101, a tank II 103, a tank II 102, a tank IV 104, a tank V 105, a tank VI 106, a pump 107, a cation exchange membrane 108, and a power source 109. Referring to FIG1 , tank I (101) includes reduction leaching of LCO, and tank II (103) includes Li + Reduction removal, tank III (102) includes removing Co by precipitation 2+ , tank IV (104) includes OER or HOR (acidic), tank V (105) includes oxidative leaching of LFP, and tank VI (106) includes HER or oxygen reduction reaction (ORR) (alkaline). The closed-loop process route is I / IV→III→II / IV→V / VI.

[0226] The closed-loop complementary recycling process of spent battery materials can be implemented in different ways.

[0227] Path 1: The flow chart in Figure 1 illustrates the recovery process from reduction leaching of spent lithium battery materials, step-by-step separation of the individual components to recovery of metal substances. The detailed operation is described below.

[0228] Step 1: Reduction leaching of waste battery materials (taking LiCoO2 or LCO as an example).

[0229] (1) This step involves electrolytic cell A which is paired with reaction cells I and IV.

[0230] (2) On the cathode side, the redox mediator 1 (RM1) in the acidic electrolyte is first reduced to RM1 at the cathode - .

[0231] (3) Including RM1 - The electrolyte flows into tank I, where RM1 - To further reduce LCO, RM1 - It is oxidized back to RM1. Under acidic conditions (pH = 0-3), the reduced oxide material gradually dissolves into Li + and Co 2+ .

[0232] (4) The electrolyte containing RM1 is pumped back into the cathode chamber, where RM1 is reduced back to RM1 - for the next round of reaction.

[0233] (5) On the anode side, when water is supplied, an OER reaction occurs to generate protons.

[0234] (6) The generated protons are transported to the cathode chamber through the cation exchange membrane.

[0235] (7) The entire electrolysis reaction is carried out continuously to achieve complete dissolution of LCO, and the monitored pH is <3 at this time.

[0236] (8) Residual undissolved impurities are removed from tank I.

[0237] Step 2: Removal of Co by precipitation 2+ .

[0238] (1) After step 1 is completed, the dissolved LCO and the Li + 、Co 2+ , RM1 and the electrolyte supporting the electrolyte flow into tank III together.

[0239] (2) In tank III, add LiOH, where Co 2+ Co(OH)2 is formed and precipitated. Co(OH)2 is then separated from the electrolyte. When the pH of the solution is higher than 10, Co 2+ Can be almost completely removed.

[0240] (3) Contains only Li + The filtered electrolyte of RM1 flows to tank II.

[0241] Step 3: Li + electrochemical removal.

[0242] (1) This step involves electrolysis cell A paired with reactor cells II and IV.

[0243] (2) In tank II, FePO4 (FP) is pre-charged.

[0244] (3) The filtered electrolyte from step 2 flows back to the cathode chamber of electrolytic cell A, and RM1 is reduced to RM1 at the cathode. - .

[0245] (4) Contains Li + and RM1 - The electrolyte flows into tank II, where RM1 - To further reduce FP, RM1 - It is oxidized back to RM1. The reduction of FP involves Li + of intercalation to form LiFePO4 (LFP).

[0246] (5) The electrolyte containing RM1 is pumped back into the cathode chamber, where RM1 is reduced back to RM1 - for the next round of reaction.

[0247] (6) On the anode side, when water is supplied, an OER reaction occurs to generate protons.

[0248] (7) The generated protons are transferred to the cathode chamber through the cation exchange membrane. These protons just compensate for the consumption in step 1.

[0249] (8) The entire electrolysis reaction is carried out continuously to achieve Li + (Li from LCO in step 1 + and LiOH from step 2 + ) completely removed.

[0250] (9) At this point, theoretically, the pH and composition of the electrolyte return to the pH and composition in step 1(1).

[0251] (10) Remove solid LFP from tank II.

[0252] Step 4: Li + Oxidative leaching and separation.

[0253] (1) This step involves electrolytic cell B paired with reaction cells V and VI.

[0254] (2) The LFP obtained in step 3 is transferred to the anode tank V.

[0255] (3) On the anode side, the redox mediator 2 (RM2) in the anolyte is first oxidized to RM2 + .

[0256] (4) Including RM2 + The electrolyte flows to tank V, where RM2 + The LFP is further oxidized, while RM2 + The oxidation of LFP involves Li + of extraction to form FP.

[0257] (5) Contains RM2 and Li + The electrolyte is pumped back into the anode chamber where RM2 is oxidized back to RM2 + for the next round of reaction.

[0258] (6) Li in the electrolyte + The ions are transported through the cation exchange membrane to the cathode chamber.

[0259] (7) On the cathode side, when water is supplied, the HER reaction occurs to produce H2 and OH - The concentration of LiOH in the cathode electrolyte in cell VI gradually increased.

[0260] (8) The entire electrolysis reaction is carried out continuously to achieve complete extraction of Li from the LFP in tank V. + .

[0261] (9) The FP obtained in trough V can be used again for Li in step 3 + and part of the generated LiOH can be used for the Co 2+ of removal.

[0262] Utilizing the above complementary and closed-loop reactions, the entire LCO recovery process only requires the supply of water and electricity. Note that in the case of supplying H2 produced from electrolyzer B, the OER reaction in electrolyzer A can be replaced by the hydrogen oxidation reaction (HR) reaction, thereby generating no additional waste (except for impurities in the waste LCO black mass, i.e., carbon black, binder, etc.), and further reducing power consumption. Ultimately, the waste LCO is decomposed into battery-grade LiOH and Co(OH)2.

[0263] In operation, instead of oxidizing LCO with a high potential redox mediator to extract Li from the host + , a low potential redox mediator (BSP-Fc(RM1)) is used to reduce LiCoO2 in the presence of protons generated by the counter electrode compartment. To facilitate the subsequent lithium ion removal process, a weak acid is used as a proton source. As a result, the insoluble LiCoO2 is decomposed into soluble Li + Ion, Co 2+ ions and H2O (in tank I). When the redox mediator is regenerated at the electrode coordinated with the oxygen evolution reaction (OER) at the counter electrode (tank IV), the generated protons are transported to the cathode compartment through the cation exchange membrane. Then, the soluble Co 2+ The ions can be separated by adding LiOH (from tank VI) and precipitated as Co(OH)2 in a separate reaction tank (tank III). Removal of Li from solution + ions can be completed with a complementary reduction reaction of the recovered FP. Using the same redox mediator RM1 with a lower potential than FP, FP is converted into Li + The selective insertion of ions leads to the reduction and formation of LFP (slot II). In addition, the counter electrode accompanies the OER reaction and transfers the generated protons to the cathode chamber, thus replenishing the proton consumption (slot IV).

[0264] Then, the redox mediator 2 (Li3[Fe(CN)6], RM2) with a higher redox potential than LFP is used to oxidize LFP (in tank V) together with Li + The LFP is transported to the cathode chamber through the membrane and continuously decomposed into FP and Li via a redox targeted reaction. + At the same time, the HER reaction at the counter electrode not only similarly produces OH -It is used to form LiOH (which can be used to precipitate Co(OH)2 in tank III), and it also produces high-purity H2 as a valuable by-product (in tank VI). Utilizing the above complementary and ring-closing reactions, under the concept of green chemistry, the waste LCO material is decomposed into high-purity LiOH and Co(OH)2.

[0265] Example 5. Strategy based on reduction redox targeting

[0266] Anthraquinone disulfonate derivatives (AQDS-(NH4)2) can be used for both the reductive decomposition of LCO and the reduction of FP due to their appropriate potential and robust stability under acidic and neutral conditions (J. Yu et al., Energy Storage Mater, 2020, 29, 216-222), thereby enabling lithium ions to be removed from the solution by embedding in the solid. Li3[Fe(CN)6] is used as a mediator to achieve high-throughput lithium ion recovery through the HER reaction in the counter electrode.

[0267] Cyclic voltammetry (CV) measurements

[0268] CV measurements were performed using an Autolab electrochemical workstation (Metrohm, PSTA30). A three-electrode cell system was used to test the CV of solid active materials and soluble redox mediators; Pt plates and Ag / AgCl were used as counter and reference electrodes, respectively.

[0269] The LiCoO2, FePO4 or LiFePO4 working electrode was prepared by coating a slurry containing LiCoO2 powder, FePO4 powder or LiFePO4 powder onto a piece of carbon paper and drying it in a vacuum oven at 60°C. The slurry was prepared by mixing LiCoO2, LiFePO4 or FePO4 powder, carbon black (CB) and polyvinylidene fluoride (PVDF) with N-methyl-2-pyrrolidone (NMP) as a solvent (LiCoO2:CB:PVDF=8:1:1). The supporting electrolyte for the CV test of LiCoO2, FePO4 and LiFePO4 was 0.5M Li2SO4 solution, and the CV data were respectively expressed as 1mV s -1 , 1mV s -1 and 2mV s -1 The scan rate is recorded.

[0270] In order to measure [Fe(CN)6] 4- / [Fe(CN)6] 3-or ferrocene derivatives, a Li3Fe(CN)6 solution (10 mL, 0.050 M) was prepared. 0.5 M Li2SO4 was used as the electrolyte and glassy carbon was used as the working electrode, with a scan rate of 10 mV s -1 .

[0271] Double-layer electrode preparation

[0272] The double-layer electrode was prepared by coating ITO glass with a 3 μm thick spacer layer of aluminum oxide (Al2O3) nanoparticles separating the LCO layer. Before coating, the ITO glass was ultrasonically treated in 5% Decon 90 solution, distilled water and ethanol three times each. The Al2O3 paste was coated on the surface of the ITO and then annealed at 400°C in air for 2h. After the Al2O3 electrode was cooled to room temperature, the LCO layer was coated on the Al2O3 film (the LCO slurry was composed of 90wt% LCO and 10wt% PVDF mixed evenly in NMP). The electrode was then dried in a vacuum oven at 60°C for 24h. The FePO4 electrode was prepared in a similar manner.

[0273] Flow battery assembly and electrochemical testing

[0274] Nafion 212 was used as a membrane to separate the anode electrode and the cathode electrode. 1×1 carbon felt or carbon paper was used as an electrode. The electrolyte was pumped through the anode tank and the cell chamber by a peristaltic pump through a PTFE tube. The Arbin battery tester was used at 50 mA cm -1 The voltage curve was measured at a constant current density.

[0275] OCP measurement

[0276] OCP test was performed with a three-electrode system. Glassy carbon and Ag / AgCl were used as working electrode and reference electrode, respectively, and the equilibrium potential of AHDS / AQDS was monitored by measuring OCP using an Autolab electrochemical workstation (Metrohm, PSTA30). FePO4 (0.75 g) was added to a 20 mL solution containing 50 mM reduced AQDS-(NH4)2 (abbreviated as AHDS). The concentration of the generated oxidized AQDS (abbreviated as AQDS) can be easily calculated using the Nernst equation (2):

[0277]

[0278] Here, E is the OCP of the AQDS / AHDS solution when reacting with FP, E0 is the formal potential of AQDS (0 V relative to SHE at pH = 4), and c is the concentration of AQDS / AHDS. The reaction rate constant (k) between FP and AHDS was determined according to the Butler-Volmer equation (3). 0) and the electron transfer coefficient (α):

[0279]

[0280] Here, i is the current, A is the area of ​​the electrode, F is the Faraday constant, R is the gas constant, and T is the temperature. The detected current i is approximated as the electrons transferred from AHDS to FP. Therefore, i can be replaced by the concentration change of AQDS, as shown in equation (4).

[0281]

[0282] Here, r is the rate of the redox targeting reaction, and V is the volume of the AQDS solution, 20 mL. The effective current can be calculated using the Butler-Volmer relationship.

[0283] Results and Discussion

[0284] First, the decomposition of LCO by reduction and the leaching of lithium by redox targeted reactions occur in separate cells used as cathode and anode reaction cells, respectively ( Figure 2 ). To avoid the influence of other metal ions on the reaction process, AQDS-(NH4)2 is used as a redox mediator with a lower reduction potential that can decompose LiCoO2 and has good reversibility for long-term operation in acid solution. The equilibrium potential difference is the thermodynamic basis of the redox targeted reaction between LCO and AQDS-(NH4)2. As determined by CV (Figure 3a), the equilibrium potential of LCO powder in 0.5M H2SO4 electrolyte is about 1.07V relative to (vs.) SHE, and the AQDS derivative exhibits excellent stability and fast kinetics in 3M acetic acid solution at a potential of 0.095V vs. SHE. A potential difference of around 1.0V will generate a huge driving force to reduce LCO by AQDS.

[0285] In order to verify the redox targeted reaction between LCO and AQDS, a double-layer electrode (inset of FIG. 3b) was constructed to simulate the reaction in the tank (M. Zhou et al., Chem 2017, 3, 1036-1049). Because the reduction leaching LCO reaction is an irreversible one-way reaction, LSV was first performed in a 3M acetic acid solution containing 5mM AQDS for concept verification. There was no obvious reduction peak on the electrode with the Al2O3 layer without LCO coating. On the contrary, the enhanced current density was continuously flattened with the LCO coating. This indicates that AQDS diffuses to the LCO surface through the Al2O3 layer after accepting electrons from the electrode, and returns to the surface of the electrode after being oxidized by LCO, causing the electrode to continuously emit electrons. In other words, the electrochemical reaction of AQDS on the electrode is combined with its regeneration in the nearby LCO layer.

[0286] To examine the redox-targeted reaction kinetics between AQDS and LCO, the OCP of 50 mM anthraquinone-2,7-disulfonate (AHDS, the reduced form of AQDS) after the addition of 0.5 g LCO powder (considerable excess) at 25 °C was monitored by potentiometry using a three-electrode setup. Due to LCO, a rapid increase in OCP from an initial -0.077 V to 0.5 V (vs. SHE) was observed after 75 min of reaction (inset of Figure 3c). Due to the dissolution of LCO, the generated Co 2+ ions lead to a complex reaction system, making it impossible to calculate the rate constant. However, from the OCP curve, the rising voltage indicates that the reaction rate between AHDS and LCO is relatively fast. As shown in Figure 3c, the LSV graph reveals that there is no obvious oxidation current, indicating that the AHDS species is almost completely oxidized in the process.

[0287] On the basis of the above, in order to realize the continuous decomposition process of LCO under acidic conditions with AQDS as redox mediator, such as Figure 2 Assemble into an electrochemical flow cell as shown in a. A 50mM AQDS-(NH4)2 solution is fed into the cathode tank together with LCO (0.2g). AQDS-(NH4)2 can be reduced to AHDS and decompose LCO, accompanied by its oxidation (Formula (5)). Then, AQDS is pumped back to the cathode chamber to be reduced back to AHDS on the electrode surface for the next round of reaction (Formula (6)). On the anode side, in the presence of water supply, OER reaction occurs to produce protons. The generated protons are transported to the cathode chamber through the Nafion 212 cation exchange membrane (Formula (7)) for charge balance. All electrolysis reactions are carried out continuously to achieve complete dissolution of LCO under the application of voltage (ΔV).

[0288] In order to accelerate the reaction rate, an electrode with an acidic OER catalyst is used on the anode side (RD Ross et al., Nat. Commun. 2021, 3036). The detailed characterization of the catalyst is as follows Figure 4 The constant current curve of the battery is shown in Figure 3d. Even at a high current of 50 mA cm -1 At a current density of 1.5 V, the battery can also continuously decompose LCO at an average voltage platform of ~1.8 V. Based on the theoretical capacity and actual charge capacity of LCO, Li + and Co 2+ The leaching rate is about 98%. After the reaction, the remaining undissolved impurities (carbon black and polymer binder, etc.) can be easily removed from the tank.

[0289] 2LiCoO2+AHDS+6H + →2Li + +2Co 2+ +AQDS+4H2O (5)

[0290] 2AQDS+4H + +4e - →2AHDS (6)

[0291] 2H2O-4e - →4H + +O2 (7)

[0292] Example 6. Selective removal and transfer of lithium ions

[0293] Although the protons in the cathode chamber will be replenished from the opposite side, it can be seen from equation (5) that 3 times more protons must be replenished to decompose 1 mol of LCO. Therefore, the concentration of protons in the solution decreases as LCO decomposes, and the reaction will stop until the protons are consumed. After the decomposition of LCO is completed, the dissolved LCO and the Li + 、Co 2+ The electrolytes of AQDS and supporting electrolyte flow together into separate tanks. As LiOH is added to the mixed solution and when pH>10, Co 2+ precipitate and can be easily separated by centrifugation or filtration (Formula (8)).

[0294] Co 2+ +2LiOH→Co(OH)2+2Li + (8)

[0295] The OCP test was performed according to the protocol in Example 5.

[0296] Results and Discussion

[0297] XRD measurements confirmed that the solid obtained was Co(OH)2. A 98.5% recovery of cobalt and a high purity of 97.6% (as determined by ICP-OES measurements, Figure 5 ). Then, AQDS and Li + The filtered electrolyte flows to the reductive lithium insertion device.

[0298] To achieve the selective removal and transfer of lithium ions from AQDS-(NH4)2, a LIB cathode material is required as a lithium intercalation carrier, which needs to have a higher potential than AQDS-(NH4)2 so that the intercalation of lithium ions can be achieved by reducing the electrode material by a redox mediator. At the same time, considering the limitation of the working voltage range in aqueous systems and because the process of releasing lithium ions from solid materials is an oxidation reaction, the solid material should have a moderate redox potential (<1V) at neutral pH. We choose iron phosphate (LP) as the lithium ion intercalation carrier.

[0299] like Figure 6 As shown in a, the potential of AQDS-(NH4)2 in 1M lithium acetate solution is -0.12V (vs. SHE) and the potential difference between AQDS-(NH4)2 and FP in neutral solution is about 500mV, which provides a driving force to reduce FP by AQDS-(NH4)2. In order to verify the redox targeting between FP and AQDS, a double layer experiment (as described in Example 5) was first used to simulate the electrochemical and chemical processes. The LSV results show that when the FP coating is present on the Al2O3 layer, the reduction current intensity is significantly enhanced ( Figure 7 ). Undoubtedly, the process of reducing and inserting lithium can proceed smoothly.

[0300] To examine the redox-targeted reaction kinetics between AQDS-(NH4)2 and FP, the OCP of 50 mM AHDS after adding 0.75 g FP powder was monitored. Figure 6 b and Figure 8 ). The potential rises rapidly from −0.12 V to 0.35 V within 35 min. According to the OCP measurement, the LSV plot reveals no obvious oxidation current, indicating that the AHDS species is almost depleted after the reaction.

[0301] Example 7. Continuous process of electrochemical reduction and lithium insertion

[0302] Use with Figure 2 The same flow cell device as shown in a was used to investigate the continuous process of electrochemical reduction and lithium insertion. + The electrolyte containing AHDS flows into the cathode tank along with the pre-loaded FePO4(FP), where AHDS reduces FP and AHDS itself is oxidized to AQDS. The reduction of FP involves Li +The electrolyte containing AQDS is then pumped back to the cathode chamber, where AQDS is reduced back to AHDS for the next reaction cycle (Equation (6)). On the anode side, similar to the first step, an OER reaction also occurs in the presence of water (Equation (7)), where the generated protons are transported to the cathode chamber through the cation exchange membrane. Figure 6 c shows the constant current curve of the battery. With Co2O3 / Ce3O4 as the OER catalyst (RD Ross et al., Nat. Commun. 2021, 3036), all electrolysis reactions proceed with the LiOH from the first step of LCO decomposition. + The removal of Co 2+ The precipitation was carried out by adding LiOH continuously. Even when the current density was as high as 50 mA cm -2 When the voltage of the flow cell is 1.8 V. 2+ The removal process introduces twice as much Li + The amount of Li from the decomposition of LCO + Together, in theory, when these lithium ions in the solution are embedded in FP, the protons produced by the OER reaction just replenish the extra protons consumed by the decomposition of LCO. Based on this, the cathode electrolyte can just be restored to its initial state before the decomposition of LCO and can be reused in the next round. By comparing the theoretical capacity of FP with the charge capacity during lithium insertion, the lithium insertion rate is calculated to be as high as 99%. Figure 6 In the XRD pattern shown in d, all index peaks of FePO4 disappear but a new pattern consistent with LiFePO4 appears. FT-IR spectrum ( Fig. 9 ) further confirmed that FePO4 had been reduced by AQDS, accompanied by Li + These results clearly show that AQDS can effectively + embedded in FePO4, thus realizing Li + fixation and transfer.

[0303] FePO4+AHDS+Li + →LiFePO4+AQDS+2H + (9)

[0304] After the above three processes, lithium ions and cobalt ions are separated, but lithium ions exist in the form of LFP and cannot be used freely. Combined with the previously reported electrochemical oxidation leaching method of LFP (J. Yu et al., Energy Environ. Sci. 2019, 12, 2672-2677), high-purity lithium hydroxide can be recovered.

[0305] Here, similar tests were performed using the above flow cell to extract lithium ions based on redox targeting. To improve the reaction rate, HER was used instead of ORR, as the sluggish kinetics of ORR limited the current density to ∼10 mA cm -2 The flow cell setup is similar to that of Figure 1. In operation, the resulting LFP material from the third step is similarly loaded into the anode reaction cell and reacts with the redox mediator [Fe(CN)6] dissolved in the anolyte. 3- The oxidation reaction decomposes into FePO4 and Li + (Equation (10)). The Li + , the reduced redox mediator [Fe(CN)6] 4- circulates to the anode chamber, where [Fe(CN)6] 4- Regenerated back to [Fe(CN)6] 3- For continuous reaction with LFP (Eq. (11)). + At the same time, the HER reaction at the counter electrode not only similarly produces OH - To form LiOH, it also produces high-purity H2 as a valuable byproduct (Eq. (12)). When a carbon felt electrode with an OER catalyst is used as the cathode, at 50 mA cm -2 At high current density, the average voltage platform is about 1.8V ( Fig.10 ). Based on the theoretical capacity of LFP and the actual value, we calculated the Li + The removal efficiency is >98%. The purity of the obtained LiOH is as high as 99.9%, which means that the obtained LiOH can be directly used to precipitate Co 2+ or for other applications. In addition, the FT-IR spectrum of LiOH is similar to that of commercially available LiOH·H2O ( Fig.11 ). More importantly, in this process, only water and electricity are consumed to obtain recyclable high-purity LiOH and FP.

[0306] [Fe(CN)6] 3- +LiFePO4→[Fe(CN)6] 4- +FePO4+Li + (10)

[0307] [Fe(CN)6] 4- -e - →[Fe(CN)6] 3- (11)

[0308] 2H2O+2e - →2OH -+H2 (12)

[0309] From the decomposition of LCO to Li + and Co 2+ The final separation and recovery of FP can be recovered and reused, and the obtained LiOH can also be directly used for Co 2+ precipitation. Under this viewpoint, after combining the above 8 equations (Equations (5)-(12)), it is easy to obtain equation (13). It can be clearly seen that by utilizing the above complementary and closed-loop reactions, the entire LCO recovery process only requires the supply of water and electricity, and no other chemical reagents need to be added to the system. Ultimately, the waste LCO is decomposed into high-grade LiOH and Co(OH)2. The continuous process showed cobalt and lithium recoveries of 95% and 92.2%, respectively ( Fig.12 ).

[0310] Carry out at 5cm 2 A continuous process of recovering 0.2 g of LCO in an electrolytic cell was performed to demonstrate the entire leaching and recovery path. 30 mL of 50 mM AQDS in 3 M acetic acid was used as the starting electrolyte. After LCO leaching ( Fig.12 a), cobalt was removed and precipitated as Co(OH)2. Then 20 mL of electrolyte was used to remove lithium ( Fig.12 b), and finally the obtained LiFePO4 was leached by 0.4M Li3Fe(CN)6 to recover Li as LiOH.

[0311] All the above electrochemical processes can be carried out at 50mAcm -2 The current density was successfully

[0312] In short, at 50mAcm -2 At a current density of 1.5 Å, the leaching rate of lithium cobalt oxide and the lithium insertion rate of FP were as high as 98% and 99%, respectively. + At 50mAcm -2 When leached from the obtained LFP at a high current density of , it can be separated as high-purity LiOH and it can not only cover the Co 2+ This attractive closed-loop route provides a new approach for the green recycling of waste battery materials, and it is the first time that metals have been separated and recovered from waste LCO batteries in the form of high-value chemicals by electrochemical and chemical methods.

[0313] Example 8. NMC electrode material

[0314] For NMC electrode materials, the reduction decomposition method is also used. Fig.10 As shown, 50 mM AQDS was used as the mediator molecule to test the cell under 0.5 M sulfuric acid. The counter electrode (anode) was subjected to the OER reaction and the entire reaction was conducted at 10 mA cm -2 At a current density of , the battery voltage is 1.7V ( Fig.13 ).

[0315] Therefore, we developed a high-throughput electrolyte flow cell system based on redox targeting, which not only achieved the continuous decomposition of waste LIB materials, but also achieved the separation and recovery of metal ions in electrode materials, and at the same time, obtained high value-added and high-purity chemical products. As a suitable redox mediator, AQDS-(NH4)2 can efficiently and continuously decompose LCO. + and Co 2+ The leaching rate is as high as 98%. At the same time, AQDS-(NH4)2 can also be used as an ideal redox mediator for reducing FP to insert lithium, achieving the decomposition of LCO and separation of metallic Li + The fast reaction kinetics also ensure that each step of the reaction is as high as 50mAcm -2 The high current density makes it possible for practical industrial applications. In addition, the complete closed-loop route does not require the addition of additional chemicals and does not cause secondary pollution, truly realizing green chemical treatment. This unique design strategy can be easily applied to other waste battery materials, such as NMC materials. These green, closed-loop technologies based on redox targeting offer the possibility of wide application in the sustainable recycling of waste batteries.

[0316] Example 9. Reduction leaching of LCO and Co 2+ and Li + Selective removal settings (path 2)

[0317] Fig.14 The reduction leaching of LCO and Co 2+ and Li + Different pathways for selective removal of (path 2). Fig.14 As described in , the device includes tank I 101, tank II 103, tank III 102, tank IV 104, a pump 107, an anion exchange membrane 201 and a power supply 109.

[0318] use Fig.14 The dual electrolyzer configuration shown, reduction leaching of LCO and Co 2+ and Li + The removal of can be carried out simultaneously. The detailed operation is described below.

[0319] Step 1: Reduction leaching of LCO using electrolytic cell A. The procedure is the same as step 1 in route 1 (see Example 4).

[0320] Step 2: Include Li + 、Co 2+ , RM1 and the leaching electrolyte of the supporting electrolyte flow into tank III, where Co 2+ It is removed by adding LiOH. The formed Co(OH)2 precipitate is separated from the electrolyte.

[0321] Step 3: Residue containing Li + and RM1 electrolyte continues to flow into tank II. With the help of electrolytic tank A', Li + It is removed by FP in tank II as described in step 3 in route 1 (see Example 4). During this process, protons accumulate in the electrolyte.

[0322] Step 4: As the pH of the electrolyte in tank II becomes <3, the electrolyte in tank II containing protons and RM1 is then returned to tank I. Those in tank I proceed again from step 1, starting a second round of reactions.

[0323] Step 5: With the FP in cell II fully converted to LFP, it is transferred to cell B as described in Path 1, Step 4 (see Figure 1 and Example 4) for oxidative leaching of LFP and Li + separation.

[0324] Example 10. Reduction leaching of LCO and Co 2+ With Li + Selective removal of (path 2)

[0325] LCO is used as an example to demonstrate the various steps of Path 2 (as described in Example 9). Strong redox mediators (RMs) with lower potentials than LCO and LFP can be used for reduction leaching. Here, two RMs are used as examples. As described in Example 5, the redox potentials of Fc-SO3Li and AQDS-2NH4 were measured in 50 mM H2SO4 by CV method.

[0326] Results and Discussion

[0327] like Fig.15 As shown, the redox potentials of Fc-SO3Li and AQDS-2NH4 are 0.31 V and 0.23 V (vs. SHE), respectively, which are lower than LCO (~1 V vs. SHE). This makes them suitable as RM1 for reduction leaching of LCO.

[0328] The reduction leaching of LCO was carried out in an electrolyte flow cell, using 40 mM Fc-SO3Li as a mediator in a 0.5 M H2SO4 solution in the cathode chamber filled with spent LCO. For the counter electrode (anode), 0.5 M H2SO4 was used as a supporting electrolyte, and the carbon material with an OER catalyst was used as an electrode for the OER reaction. Fig.16 As shown, at 50mA / cm 2 At a constant current density of 1.5 Å, the average voltage plateau is about 1.60 V. Calculations based on the theoretical and actual capacities of LCO show that the leaching rate of the material is 98%.

[0329] Add LiOH to the leached electrolyte, stir and filter. 2+ It is almost completely separated from the solution in the form of Co(OH)2 precipitate. Fig.17 The XRD of Co(OH)2 is shown in FIG. 1 , and the recovery rate of cobalt reaches 95% at pH=10.

[0330] Contains Li + and Fc-SO3 - The filtrate was directly used as the catholyte in the same electrolyte flow cell, and FP was installed in the cell for Li + Remove. At 50mA / cm 2 The average voltage platform at constant current density is about 1.7 to 1.9 V. Based on the theoretical capacity and actual capacity of FP, Li + The embedding rate is 97%, such as Fig.18 As shown in a. Fig.18 b shows the XRD pattern of the obtained LFP after lithium insertion.

[0331] The obtained LFP was transferred to the anode reservoir of the second electrolyte circulation cell, which contained Li3[Fe(CN)6] as the redox mediator (RM2). 3- Continuously oxidized and decomposed into FP and Li + The HER reaction occurs at the counter electrode and produces OH with the supply of water. - During this process, Li + The ions pass through the membrane to the cathode, forming a LiOH solution in the cathode tank, thus realizing lithium recovery. Fig.19 As shown in a, at 50 mA / cm 2 At a constant current density of , the battery voltage is about 1.8-1.9 V. The XRD diagram shows that after lithium leaching, the original LFP solid becomes FP ( Fig.19 b).

Claims

1. A method for recycling waste battery materials, the method comprising the following steps: (a) providing a first reaction chamber connected to a cathode side fluid of an electrolyzer, the electrolyzer comprising a cathode chamber comprising a cathode, an anode chamber comprising an anode, and a cation exchange membrane separating the cathode chamber and the anode chamber from each other, wherein the anode side of the electrolyzer is configured to generate protons by an oxygen evolution reaction or a hydrogen oxidation reaction, wherein in an initial state, the first reaction chamber comprises: Contains LiCoO2 and / or LiNi x Mn y Co z Solid waste battery materials of O2; and an acidic electrolyte comprising a first redox mediator capable of being reduced at the cathode, and During a first reduction cycle, an acidic electrolyte from the first reaction chamber is provided to a first cathode chamber to provide a reduced first redox mediator, and the acidic electrolyte is returned to the first reaction chamber, wherein the reduced redox mediator reacts with solid spent battery material to produce soluble Li + 、Co 2+ And when Ni exists 2+ Ions and Mn 2+ ions, while the reduced first redox mediator is oxidized back to its original form and supplies protons from the anode chamber through the cation exchange membrane, During the subsequent reduction cycle, the acidic electrolyte from the first reaction chamber contains the first redox mediator and Li + 、Co 2+ And when Ni exists 2+ Ions and Mn 2+ ion, Subsequent reaction cycles continue until Li, Co and, if present, Ni and Mn have been dissolved from the solid spent battery material, thereby containing the first redox mediator and Li + 、Co 2+ And when Ni exists 2+ Ions and Mn 2+ An ionic acidic electrolyte is supplied to the second reaction chamber; (b) in the second reaction chamber, the acidic electrolyte comprises the first redox mediator and Li + 、Co 2+ And when Ni exists 2+ Ions and Mn 2+ ions, adding LiOH to make Co 2+ And when Ni exists 2+ Ions and Mn 2+ ion precipitation, thereby providing a + of filtered alkaline electrolyte, when Co 2+ And when Ni exists 2+ Ions and Mn 2+ When ions are substantially or completely removed from the filtered alkaline electrolyte by precipitation, the filtered alkaline electrolyte is supplied to a third reaction chamber; (c) in an initial state, the reaction chamber contains FePO4 and receives filtered alkaline electrolyte from the second reaction chamber, During the first reaction cycle, the filtered alkaline electrolyte is supplied from the third reaction chamber to the cathode chamber to provide a first redox mediator containing reduced Li + ions, and the electrolyte is returned to the third reaction chamber, wherein the reduced redox mediator reacts with FePO4 to produce LiFePO4, the reduced first redox mediator is oxidized back to its original form and protons are supplied from the anode chamber through the cation exchange membrane, During the subsequent reaction cycle, the electrolyte from the third reaction chamber contains the first redox mediator and a reduced concentration of Li + ion, The subsequent reaction cycle continues until Li + Ions are substantially or completely removed from the electrolyte so that the electrolyte matches or substantially matches the acidic electrolyte of step (b), at which point the LiFePO4 and any residual FePO4 are collected.

2. The method according to claim 1, further comprising the steps of: (i) providing a fourth reaction chamber connected to the anode side fluid of an electrolyzer, the electrolyzer comprising an anode chamber comprising an anode, a cathode chamber comprising a cathode, and a cation exchange membrane separating the cathode chamber and the anode chamber from each other, wherein the cathode side of the electrolyzer is configured to generate hydrogen gas and hydroxide ions by a hydrogen evolution reaction, the cathode chamber being connected to the storage tank fluid, wherein in an initial state, the fourth reaction chamber comprises: The fourth reaction chamber contains LiFePO4 and any residual FePO4 collected from step (d) of claim 1, and an electrolyte comprising a second redox mediator capable of being oxidized at the anode; and The storage tank includes water, During a first reaction cycle, the electrolyte from the fourth reaction chamber is provided to the anode chamber to provide an oxidized second redox mediator, and the electrolyte is returned to the fourth reaction chamber, wherein the oxidized redox mediator reacts with LiFePO4 to provide FePO4 and Li + ion, During the subsequent reaction cycle, the redox mediator and Li + An ionic electrolyte is supplied to the anode chamber, wherein: The redox mediator is converted to an oxidized redox mediator; and At least some Li + Ions are transported through the cation exchange membrane into the cathode chamber, and thus transferred to said storage tank, Subsequent reaction cycles continue until the LiFePO4 is substantially or completely consumed and the storage tank contains aqueous lithium hydroxide.

3. The method according to claim 1 or claim 2, wherein the first redox mediator has a lower x Mn y Co z The redox potential of O2, optionally wherein the redox potential of the first redox mediator is less than 0.4 V relative to a standard hydrogen electrode (SHE), for example, 0.05 to 0.39 V relative to SHE, for example, about 0.23 V relative to SHE or about 0.31 V relative to SHE.

4. The method according to claim 4, wherein the first redox mediator is one or both of Fe-SO3Li and AQDS-2NH4.

5. A method according to any one of the preceding claims, wherein the concentration of the first redox mediator in the acidic electrolyte is 1 to 100 mM, such as 2 to 50 mM, such as about 40 mM or about 5 mM.

6. A method according to any one of the preceding claims, wherein the acidic electrolyte is formed from water and an acidic compound, optionally wherein the concentration of the acidic compound is 0.2M to 5M, such as about 0.4M to 3M, further optionally wherein the acidic compound is sulfuric acid or acetic acid.

7. The method according to any one of claims 2 to 6, wherein the second redox mediator is Li3[Fe(CN6).

8. The method according to any one of the preceding claims, wherein the method is operated as a closed loop.

9. An electrolysis device comprising: an electrolytic cell comprising a first cathode chamber comprising a cathode, a first anode chamber comprising an anode, and a cation exchange membrane separating the first cathode chamber and the first anode chamber from each other; The first cathode tank to the third cathode tank, wherein: The first cathode slot is fluidly connected to at least the cathode chamber and the second cathode slot; The second cathode cell is fluidly connected to at least the first cathode cell and the third cathode cell and is capable of receiving LiOH; The third cathode slot is fluidly connected to at least the first cathode slot, the second cathode slot and the first cathode chamber; and an anode cell fluidly connected to said first anode chamber, wherein: Each of the first cathode cell and the third cathode cell may be independently selected to be in fluid connection with the cathode chamber at any given time; The first cathode cell is configured to receive spent battery material and electrolyte and to supply the liquid to the second cathode cell; the second cathode cell being configured to receive liquid from the first cathode cell and to receive LiOH in solid and / or liquid form and to supply liquid to the third cathode cell; and The third cathode cell is configured to receive liquid from the second cathode cell.

10. An electrolysis device comprising: a first electrolytic cell comprising a first cathode chamber comprising a cathode, a first anode chamber comprising an anode, and a cation exchange membrane separating the first cathode chamber and the first anode chamber from each other; a second electrolytic cell comprising a second cathode chamber comprising a cathode, a second anode chamber comprising an anode, and a cation exchange membrane separating the first cathode chamber and the first anode chamber from each other; a first anode cell fluidly connected to the first anode chamber; a second anode tank in fluid communication with the second anode chamber; a first cathode cell fluidly connected to the first cathode chamber; a second cathode cell fluidly connected to the second cathode chamber; A third cathode cell is fluidly connected to the first cathode cell and the second cathode cell.

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