Electrochemical system for recycling metals from spent ternary lithium batteries, treatment method

Abstract

The application provides an electrochemical system and a treatment method for recycling metals from waste ternary lithium batteries. The electrochemical system comprises a reaction chamber, a counter electrode isolation chamber, and a reference monitoring chamber. The reaction chamber and the counter electrode isolation chamber are separated by a cation exchange membrane, and the reaction chamber is connected to the reference monitoring chamber through a salt bridge. The reaction chamber is provided with a working electrode, the counter electrode isolation chamber is provided with a counter electrode, and the reference monitoring chamber is provided with a reference electrode. The material of the working electrode includes positive black powder of the waste ternary lithium battery. The positive black powder of the waste ternary lithium battery is directly used to form the working electrode, and the three-chamber electrolytic cell structure is formed by the reaction chamber and the counter electrode isolation chamber separated by the cation exchange membrane and the reference monitoring chamber connected by the salt bridge, thereby effectively improving the leaching rate of valuable metals leached from the positive black powder and improving the stability of the electrochemical system.

Description

Technical Field

[0001] This application relates to the field of battery recycling technology, and in particular to an electrochemical system and processing method for recycling metals from waste ternary lithium batteries. Background Technology

[0002] Ternary lithium-ion batteries, with their advantages of high energy density and long cycle life, have been widely used in new energy vehicles and consumer electronics. With the surge in the scale of retired batteries, the efficient recovery of valuable metals from spent ternary batteries (lithium nickel cobalt manganese oxide) has demonstrated significant economic and environmental benefits. However, traditional recycling processes mainly rely on strong acids and chemical reducing agents for high-temperature leaching, which faces technical bottlenecks such as high energy consumption, severe equipment corrosion, poor selectivity in multi-metal co-solution, and high wastewater treatment costs.

[0003] In recent years, electrochemical leaching technology has attracted much attention from the academic community due to its mild reaction conditions and controllable process. For example, CN120527502A discloses a suspension electrolytic leaching method for cathode materials of retired lithium-ion batteries, which prepares a metal leachate by suspending and electrolyzing cathode material black powder. However, current traditional electrochemical leaching technologies are mostly based on black powder suspension systems. During the leaching process, some metal ions are prone to competitive reduction and deposition in the cathode region. This not only leads to the loss of valuable metals but also reduces cathode stability and affects the long-term operation of the system. Summary of the Invention

[0004] Therefore, it is necessary to provide an electrochemical system and treatment method for recycling metals from waste ternary lithium batteries with high metal recovery rate and stability.

[0005] In a first aspect, this application provides an electrochemical system for recycling metals from waste ternary lithium batteries.

[0006] An electrochemical system for recycling metals from waste ternary lithium batteries includes a reaction chamber, a counter-electrode isolation chamber, and a reference monitoring chamber. The reaction chamber and the counter-electrode isolation chamber are separated by a cation exchange membrane, and the reaction chamber is connected to the reference monitoring chamber by a salt bridge.

[0007] The reaction chamber is equipped with a working electrode, the counter electrode isolation chamber is equipped with a counter electrode, and the reference monitoring chamber is equipped with a reference electrode. The working electrode, the counter electrode, and the reference electrode are connected to a potential controller. The material of the working electrode includes the positive electrode black powder of waste ternary lithium batteries.

[0008] In some embodiments, the method for preparing the working electrode includes:

[0009] Dismantle, crush, and screen waste ternary lithium batteries to obtain positive electrode black powder;

[0010] Polytetrafluoroethylene (PTFE) is mixed and sheared with the positive electrode black powder to form a fibrillated electrode mixture, wherein the mass ratio of PTFE to the positive electrode black powder is 1:(5~9).

[0011] The fibrillated electrode mixture is rolled onto the current collector, forming a pre-compression layer of 0.3 mm to 0.6 mm on at least a portion of the surface of the current collector. The pre-compression layer is then hot-pressed and dried to form the working electrode.

[0012] In some embodiments, the hot pressing process satisfies one or more of the following (1) to (3):

[0013] (1) The temperature of hot pressing is 90℃~100℃;

[0014] (2) The pressure for hot pressing is 5MPa~10MPa;

[0015] (3) The hot pressing time is 3 min to 5 min.

[0016] In some embodiments, the reaction chamber is also provided with an ion-selective electrode.

[0017] In a second aspect, this application provides a method for recovering metals from waste ternary lithium batteries.

[0018] A method for recovering metals from spent ternary lithium batteries, employing the aforementioned electrochemical system, includes the following steps:

[0019] The first reaction solution is loaded into the reaction chamber, the buffer solution is loaded into the counter electrode isolation chamber, and the electrolyte solution is loaded into the reference monitoring chamber. The working electrode is controlled to perform the first electrolysis treatment in the range of +0.3V to +0.85V.

[0020] Empty the solution in the reaction chamber, fill the reaction chamber with a second reaction solution, control the working electrode to perform a second electrolysis treatment in the range of -0.85V to -0.4V, collect the solution in the reaction chamber, and obtain the leachate;

[0021] The first reaction solution comprises sulfate, citric acid, and tartaric acid, and contains citrate or hydrogen tartrate; the second reaction solution comprises sulfate, Fe... 2+ - Tartaric acid complex, citric acid and tartaric acid, and contains citrate or hydrogen tartrate.

[0022] In some embodiments, the second electrolysis process includes the following steps:

[0023] The working electrode is controlled to perform the third electrolysis at -0.6V to -0.4V;

[0024] The working electrode is controlled to perform a fourth electrolysis at -0.85V to -0.6V, wherein the potential of the third electrolysis is positive than the potential of the fourth electrolysis.

[0025] In some embodiments, the first reaction solution comprises 0.25M~0.35M citric acid, 0.12M~0.2M tartaric acid, and 0.1M~0.2M sulfate, and the first reaction solution further comprises one of 0.15M~0.3M citrate or 0.15M~0.3M hydrogen tartrate.

[0026] In some embodiments, the buffer solution includes citric acid, sodium citrate, and sodium sulfate.

[0027] In some embodiments, the electrolyte solution includes potassium chloride and potassium citrate.

[0028] In some embodiments, the method for preparing the second reaction solution includes:

[0029] Use the first reaction solution as the base solution;

[0030] Add 0.04M~0.06M of soluble ferrous salt to the base solution and continue mixing and stirring to obtain the second reaction solution.

[0031] Compared with traditional solutions, this application has the following advantages:

[0032] The electrochemical system for recovering metals from waste ternary lithium batteries provided in this application directly uses the cathode black powder from waste ternary lithium batteries to form the working electrode. It employs a three-chamber electrolytic cell structure consisting of a reaction chamber separated by a cation exchange membrane, a counter-electrode isolation chamber, and a reference monitoring chamber connected by a salt bridge. This effectively improves the leaching rate of valuable metals from the cathode black powder and enhances the stability of the electrochemical system. Specifically, this application uses a cation exchange membrane to block organic matter and multivalent metal ions from entering the counter-electrode isolation chamber from the reaction chamber. This not only suppresses side reactions and avoids gas interference with reaction mass transfer but also prevents the loss of metal ions. Directly preparing the cathode black powder as the working electrode helps improve electron conduction and mass transfer efficiency, thereby increasing the metal recovery rate and stability. Furthermore, this scheme has strong compatibility with cathode black powder raw materials, eliminating the need for complex pretreatment and impurity removal processes. Cathode black powder mixed with small amounts of negative electrode graphite black powder, positive electrode current collector aluminum foil fragments, or conductive carbon copper particles can all be used directly as raw materials.

[0033] The method for recovering metals from spent ternary lithium batteries provided in this application effectively utilizes the differences in redox reactions of different metals or their compounds at specific potentials through staged electrolysis of a specific reaction solution in a reaction chamber. This allows for the efficient and selective leaching of target valuable metals from the working electrode. Specifically, in the first electrolysis process, by applying a specific positive potential, impurity metals such as Al, Cu, and Fe in the working electrode can be efficiently leached under the action of the first reaction solution. This process not only removes impurities but also helps to increase the specific surface area of ​​the working electrode, exposing more active sites. In the second electrolysis process, by applying a specific negative potential and introducing Fe... 2+ The second reaction solution contains a tartaric acid complex, which possesses mild reducing properties and can effectively disrupt the crystal structure of the cathode material, achieving efficient leaching of target valuable metals such as Ni, Co, Mn, and Li. Furthermore, the method for recovering metals from spent ternary lithium batteries provided in this application does not require strong reducing agents or strong acids, and Fe... 2+ The reducing medium is oxidized Fe 3+ It can be restored and recycled, possessing the advantages of being green, environmentally friendly, and highly economical. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0035] Figure 1 This is an electrochemical system for recycling metals from waste ternary lithium batteries according to one embodiment of this application.

[0036] Figure Labels

[0037] 110. Reaction chamber; 120. Counter electrode isolation chamber; 130. Reference monitoring chamber; 210. Working electrode; 220. Counter electrode; 230. Reference electrode; 310. Cation exchange membrane; 320. Salt bridge. Detailed Implementation

[0038] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, a detailed description of specific embodiments of this application is provided below. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0039] In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. In this application, "at least one" means one or more, such as one, two, or more than two. "Multiple" or "several" means at least two, such as two, three, etc.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0041] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0042] Unless otherwise specified, all steps in this application may be performed sequentially or randomly. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0043] In this application, "above" or "below" includes the number itself. For example, "below 1" includes 1.

[0044] Unless otherwise specified, the temperature parameters in this application are permitted to be either constant-temperature treatment or variations within a certain temperature range. It should be understood that the constant-temperature treatment allows temperature fluctuations within the precision range of the instrument control, such as ±5℃, ±4℃, ±3℃, ±2℃, or ±1℃.

[0045] In a first aspect, this application provides an electrochemical system for recovering metals from spent ternary lithium batteries, which has a high metal recovery rate and stability.

[0046] For example, please see Figure 1 , Figure 1This application describes an electrochemical system for recovering metals from spent ternary lithium batteries, as described in one embodiment. In this embodiment, the electrochemical system includes a reaction chamber 110, a counter electrode isolation chamber 120, and a reference monitoring chamber 130. The reaction chamber 110 and the counter electrode isolation chamber 120 are separated by a cation exchange membrane 310, and the reaction chamber 110 is connected to the reference monitoring chamber 130 via a salt bridge 320. The reaction chamber 110 is equipped with a working electrode 210, the counter electrode isolation chamber 120 is equipped with a counter electrode 220, and the reference monitoring chamber 130 is equipped with a reference electrode 230. The working electrode 210, counter electrode 220, and reference electrode 230 are connected to a potentiometer. The material of the working electrode 210 includes the positive electrode black powder from spent ternary lithium batteries.

[0047] The electrochemical system for recovering metals from waste ternary lithium batteries provided in this application directly uses the positive electrode black powder of waste ternary lithium batteries to form the working electrode 210, and adopts a three-chamber electrolytic cell structure consisting of a reaction chamber 110 separated by a cation exchange membrane 310, a counter electrode isolation chamber 120, and a reference monitoring chamber 130 connected by a salt bridge 320. This effectively improves the leaching rate of valuable metals in the positive electrode black powder and enhances the stability of the electrochemical system. Specifically, this application uses a cation exchange membrane 310 to block organic matter and polyvalent metal ions from entering the counter-electrode isolation chamber 120 from the reaction chamber 110. This not only suppresses side reactions and avoids gas interference with mass transfer, but also prevents the loss of metal ions. Directly preparing the positive electrode black powder as the working electrode 210 helps to improve electron conduction and mass transfer efficiency, and improve metal recovery rate and stability. Furthermore, this method has strong compatibility with the raw materials of the positive electrode black powder, and does not require a complex pretreatment and impurity removal process for the positive electrode black powder. Whether the positive electrode black powder is mixed with a small amount of negative electrode graphite black powder, positive electrode current collector aluminum foil fragments, or conductive carbon copper particles, it can be used directly as a raw material.

[0048] In some embodiments, the method for preparing the working electrode includes:

[0049] Dismantle, crush, and screen waste ternary lithium batteries to obtain positive electrode black powder;

[0050] Polytetrafluoroethylene is mixed and sheared with positive electrode black powder to form a fibrillated electrode mixture;

[0051] The original fiberized electrode mixture is rolled onto the current collector to form a pre-compression layer of 0.3 mm to 0.6 mm on at least a portion of the surface of the current collector. The pre-compression layer is then hot-pressed and dried to form the working electrode 210.

[0052] In this embodiment, a fibrillated electrode mixture is formed by mixing and shearing polytetrafluoroethylene (PTFE) with positive electrode black powder. The fibrillation properties of PTFE can be used to combine the conductive components originally contained in the positive electrode black powder, which helps to form a working electrode 210 with a dense conductive network.

[0053] Optionally, a pre-compression layer of 0.3 mm to 0.6 mm is formed on both sides of the current collector.

[0054] Optionally, the mass ratio of polytetrafluoroethylene (PTFE) to cathode black powder can be, but is not limited to, 1:5, 1:6, 1:7, 1:8, 1:9, or other values ​​within the range of 1:(5~9). The working electrode 210 of this application relies on the conductive carbon inherent in the cathode black powder to construct a conductive network, eliminating the need for additional conductive agents. Maintaining the mass ratio of PTFE to cathode black powder at the aforementioned ratio helps to ensure good conductivity while guaranteeing the integrity and mechanical stability of the electrode structure, and exposes sufficient reactive sites to improve reactivity.

[0055] In some embodiments, the mass ratio of polytetrafluoroethylene (PTFE) to cathode black powder is 1:(5-9). Optionally, the mass ratio of PTFE to cathode black powder can be, but is not limited to, other values ​​within the range of 1:5, 1:6, 1:7, 1:8, 1:9, or 1:(5-9). Studies have shown that maintaining the PTFE to cathode black powder at the above-mentioned mass ratio helps to improve the electron conduction and mass transfer efficiency of the working electrode 210, thereby improving the metal leaching rate and enhancing stability.

[0056] In some embodiments, the spent ternary lithium batteries include one or more of NCM111, NCM523, NCM622, and NCM811. The electrochemical system and processing method provided in this application have good process compatibility with spent ternary lithium batteries of different NCM systems.

[0057] In some embodiments, the positive electrode black powder includes LiNixCoyMnzO2 and conductive carbon.

[0058] In some embodiments, the current collector includes a titanium mesh current collector.

[0059] In some embodiments, the counter electrode 220 comprises an inert electrode. Optionally, the inert electrode comprises a titanium plate.

[0060] In some embodiments, the hot pressing temperature is 90°C to 100°C. Optionally, the hot pressing temperature can be, but is not limited to, 90°C, 92°C, 94°C, 96°C, 98°C, 100°C, or other values ​​within the range of 90°C to 100°C.

[0061] In some embodiments, the pressure of the hot pressing treatment is 5 MPa to 10 MPa. Optionally, the pressure of the hot pressing treatment can be, but is not limited to, 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa, 10 MPa, or other values ​​within the range of 5 MPa to 10 MPa.

[0062] In some embodiments, the hot pressing time is 3 to 5 minutes. Optionally, the hot pressing time can be, but is not limited to, 3 minutes, 4 minutes, 5 minutes, or other values ​​within the range of 3 to 5 minutes.

[0063] Maintaining the hot pressing process within the aforementioned temperature, pressure, and time range helps the pre-pressed layer and the current collector to form a stable bond structure.

[0064] In some embodiments, the reaction chamber 110 is also provided with an ion-selective electrode. It is understood that the ion-selective electrode is used to detect the ion concentration of the solution in the reaction chamber 110.

[0065] In a second aspect, this application provides a method for recovering metals from spent ternary lithium batteries using the aforementioned electrochemical system.

[0066] An exemplary method for recovering metals from spent ternary lithium batteries includes the following steps:

[0067] The first reaction solution is loaded into the reaction chamber, the buffer solution is loaded into the counter electrode isolation chamber, and the electrolyte solution is loaded into the reference monitoring chamber. The working electrode is controlled to perform the first electrolysis treatment in the range of +0.3V to +0.85V.

[0068] Empty the solution in the reaction chamber, fill the reaction chamber with a second reaction solution, control the working electrode to perform a second electrolysis treatment in the range of -0.85V to -0.4V, collect the solution in the reaction chamber, and obtain the leachate;

[0069] The first reaction solution comprises sulfate, citric acid, and tartaric acid, and contains citrate or hydrogen tartrate; the second reaction solution comprises sulfate, Fe... 2+ - Tartaric acid complex, citric acid and tartaric acid, and contains citrate or hydrogen tartrate.

[0070] The method for recovering metals from spent ternary lithium batteries provided in this application effectively utilizes the differences in redox reactions of different metals or their compounds at specific potentials through staged electrolysis of a specific reaction solution in a reaction chamber. This allows for the efficient and selective leaching of target valuable metals from the working electrode. Specifically, in the first electrolysis process, by applying a specific positive potential, impurity metals such as Al, Cu, and Fe in the working electrode can be efficiently leached under the action of the first reaction solution. This process not only removes impurities but also helps to increase the specific surface area of ​​the working electrode, exposing more active sites. In the second electrolysis process, by applying a specific negative potential and introducing Fe... 2+The second reaction solution contains a tartaric acid complex, which possesses mild reducing properties and can effectively disrupt the crystal structure of the cathode material, achieving efficient leaching of target valuable metals such as Ni, Co, Mn, and Li. Furthermore, the method for recovering metals from spent ternary lithium batteries provided in this application does not require strong reducing agents or strong acids, and Fe... 2+ The reducing medium is oxidized Fe 3+ It can be restored and recycled, possessing the advantages of being green, environmentally friendly, and highly economical.

[0071] Studies have shown that in the first electrolytic depurification stage, citric acid and tartaric acid can form stable soluble complexes with Al, Cu, and Fe ions, effectively inhibiting the formation of metal hydroxide precipitates. This solves the problems of electrochemical passivation caused by precipitates covering the electrode surface and the physical encapsulation of active particles hindering mass transfer. Simultaneously, the buffer system constructed from citric acid-citrate or tartaric acid-hydrogen tartrate allows the entire reaction process to operate stably in a mild pH environment, avoiding the severe corrosion and damage to the reaction equipment caused by traditional strong acid leaching processes. In this optimized liquid environment, the second electrolysis stage begins, where Fe... 2+ As a highly efficient electron transfer medium, it reduces and leachs specific components from the working electrode, promoting the reduction and leaching of Ni in the crystal lattice. 2+ Co 2+ Mn 2+ and Li + Highly efficient dissolution, accompanied by Fe 2+ Oxidized to Fe 3+ Within the specific cathode potential window applied, the generated Fe 3+ After diffusing to the electrode surface, it can directly gain electrons and be reduced and regenerated into Fe. 2+ This enables in-situ recycling of the reducing medium, transforming the traditional solid-solid direct electron transfer into a highly efficient homogeneous chemical reduction and interfacial reaction process, significantly improving the leaching rate of the target valuable metal and the system current efficiency.

[0072] Optionally, after the first electrolytic treatment, the solution in the reaction chamber is collected to obtain a second leachate. The second leachate is rich in metal ions such as Cu, Al, and Fe.

[0073] In this embodiment, each potential range is obtained using Ag / AgCl as a reference electrode, and the potential is adjusted by a potential controller.

[0074] In some embodiments, the second electrolysis process includes the following steps:

[0075] The working electrode is controlled to perform the third electrolysis at -0.6V to -0.4V;

[0076] The working electrode is controlled to perform a fourth electrolysis at -0.85V to -0.6V, wherein the potential of the third electrolysis is positive than the potential of the fourth electrolysis.

[0077] Research has shown that segmented electrolysis is used in the second electrolysis process. The third electrolysis is carried out at -0.6V to -0.4V, and the fourth electrolysis is carried out at -0.85V to -0.6V. This is more conducive to pre-activating the reaction interface and helps to reduce concentration polarization, thereby improving the leaching rate of the target metal.

[0078] In some embodiments, the first reaction solution comprises 0.25M~0.35M citric acid, 0.12M~0.2M tartaric acid, and 0.1M~0.2M sulfate. The first reaction solution also includes one of 0.15M~0.3M citrate or 0.15M~0.3M hydrogen tartrate. Maintaining the composition of the first reaction solution within the above concentration range allows the first reaction solution to maintain an appropriate pH range. Simultaneously, citric acid and tartaric acid can form stable complexes with metal ions to inhibit hydrolysis.

[0079] In some embodiments, before filling the reaction chamber with the second reaction solution, a step of cleaning the working electrode with a cleaning solution is included to further remove residual impurities, especially to prevent Cu deposition in subsequent reactions. Optionally, the cleaning solution includes deionized water. Optionally, the cleaning method includes rinsing and soaking.

[0080] In some embodiments, the cleaning endpoint of the working electrode is defined as follows: after immersing the working electrode in 500 mL of deionized water at room temperature for 10 min, the conductivity of the deionized water is less than 50 μS / cm.

[0081] In some embodiments, the buffer solution includes citrate-sodium citrate and sodium sulfate. This buffer solution effectively absorbs or neutralizes hydrogen ions or hydroxide ions continuously generated during electrolysis, maintaining a stable pH value in the system, thereby ensuring the continuous and efficient leaching reaction in the main reaction chamber. Optionally, the buffer solution includes 0.05M~0.2M citrate-sodium citrate and 0.4M~0.6M sodium sulfate.

[0082] In some embodiments, the electrolyte solution includes potassium chloride and potassium citrate. Optionally, the electrolyte solution includes 2M to 3.5M potassium chloride and 0.03M to 0.1M potassium citrate.

[0083] In some embodiments, the method for preparing the second reaction solution includes:

[0084] Use the first reaction solution as the base solution;

[0085] Add 0.04M~0.06M of soluble ferrous salt to the base solution and continue mixing and stirring to obtain the second reaction solution.

[0086] The present application will be further described in detail below with reference to specific embodiments.

[0087] Unless otherwise specified, the raw materials used in the following specific embodiments and comparative examples are all commercially available products; the instruments used are all commercially available products; and the processes used are all conventionally selected by those skilled in the art unless otherwise specified.

[0088] In the following specific examples and comparative examples, the electrolyte solutions used were all saturated salt bridge solutions of 3M KCl and 0.05M potassium citrate.

[0089] Example 1

[0090] This embodiment provides a method for recovering metals from waste ternary lithium batteries.

[0091] Please see Figure 1 The electrochemical system used in this treatment method includes a reaction chamber 110, a counter electrode isolation chamber 120, and a reference monitoring chamber 130. The reaction chamber 110 and the counter electrode isolation chamber 120 are separated by a cation exchange membrane 310, and the reaction chamber 110 is connected to the reference monitoring chamber 130 via a salt bridge 320. The reaction chamber 110 is equipped with a working electrode 210 and an independent ion-selective electrode. The counter electrode isolation chamber 120 is equipped with a counter electrode 220, and the reference monitoring chamber 130 is equipped with a reference electrode 230 (Ag / AgCl). The working electrode 210, the counter electrode 220, and the reference electrode 230 are connected to a potentiometer. The material of the working electrode 210 includes the positive electrode black powder from waste ternary lithium batteries.

[0092] The method for preparing the working electrode is as follows:

[0093] Waste NCM523 ternary lithium batteries were disassembled, crushed, sieved, and dried to obtain positive electrode black powder. Polytetrafluoroethylene (PTFE) and the positive electrode black powder were mixed at a mass ratio of 1:7 and fed into a planetary mixer. The mixture was premixed at 400 rpm for 10 minutes, then sheared at 1000 rpm for 20 minutes to obtain a fibrillated electrode mixture. This fibrillated electrode mixture was coated onto both sides of a titanium mesh current collector to form a pre-compression layer of approximately 0.5 mm. The layer was then transferred to a flatbed hot press and held at 90°C and 8 MPa for 4 minutes. After vacuum drying at 100°C for 2 hours, the layer was cut along the edge, leaving a bare titanium area as the external circuit clamping end, resulting in an effective area of ​​50 cm². 2 Working electrode.

[0094] The processing method in this embodiment is as follows:

[0095] The first reaction solution, buffer solution, and electrolyte solution are respectively filled into the reaction chamber 110, the counter electrode isolation chamber 120, and the reference monitoring chamber 130. After the first electrolysis treatment, the electrolyte in the reaction chamber 110 is removed, and the working electrode is rinsed with deionized water for 10 minutes and soaked for 10 minutes.

[0096] The second reaction solution is filled into the reaction chamber 110 and subjected to a second electrolysis treatment to obtain a metal leachate.

[0097] The composition of the first reaction solution, the second reaction solution, and the buffer solution in this embodiment, as well as the electrolysis control process of the first electrolysis treatment and the second electrolysis treatment, are detailed in Table 1.

[0098] Example 2

[0099] The composition of the first reaction solution, the second reaction solution, and the buffer solution used in this embodiment, as well as the electrolysis control process of the first and second electrolysis treatments, are detailed in Table 1. Other operations in this embodiment differ from those in Embodiment 1 in that:

[0100] The method for preparing the working electrode is as follows:

[0101] Waste NCM523 ternary lithium batteries were dismantled, crushed, sieved, and dried to obtain positive electrode black powder. Polytetrafluoroethylene (PTFE) and the black powder were mixed at a mass ratio of 1:9 and fed into a planetary mixer. The mixture was premixed at 400 rpm for 10 minutes, then sheared at 1000 rpm for 20 minutes to obtain a fibrillated electrode mixture. This fibrillated electrode mixture was coated onto both sides of a titanium mesh current collector to form a pre-compression layer of approximately 0.3 mm. The mixture was then transferred to a flatbed hot press and held at 95°C and 5 MPa for 3 minutes. After vacuum drying at 100°C for 2 hours, it was cut along the edge, leaving a bare titanium area as the external circuit clamping end, resulting in an effective area of ​​50 cm². 2 Working electrode.

[0102] Example 3

[0103] The composition of the first reaction solution, the second reaction solution, and the buffer solution used in this embodiment, as well as the electrolysis control process of the first and second electrolysis treatments, are detailed in Table 1. Other operations in this embodiment differ from those in Embodiment 1 in that:

[0104] The method for preparing the working electrode is as follows:

[0105] Waste NCM523 ternary lithium batteries were dismantled, crushed, sieved, and dried to obtain positive electrode black powder. Polytetrafluoroethylene (PTFE) and the black powder were mixed at a mass ratio of 1:5 and fed into a planetary mixer. The mixture was premixed at 400 rpm for 10 minutes, then sheared at 1000 rpm for 20 minutes to obtain a fibrillated electrode mixture. This fibrillated electrode mixture was coated onto both sides of a titanium mesh current collector to form a pre-pressed layer of approximately 0.6 mm. The layer was then transferred to a flatbed hot press and held at 100°C and 10 MPa for 5 minutes. After vacuum drying at 100°C for 2 hours, the layer was cut along the edge, leaving a bare titanium area as the external circuit clamping end, resulting in an effective area of ​​50 cm². 2 Working electrode.

[0106] Example 4

[0107] The differences between this embodiment and Embodiment 1 are shown in Table 1.

[0108] Example 5

[0109] The differences between this embodiment and Embodiment 1 are shown in Table 1.

[0110] Example 6

[0111] The differences between this embodiment and Embodiment 1 are shown in Table 1.

[0112] Table 1 Comparison of processing methods in Examples 1-6

[0113]

[0114] Note: In Table 1, "Same as left" in the "Composition of Second Reaction Solution" column means that the second reaction solution also contains the components of the first reaction solution in the same group (initial). For example, the second reaction solution in Example 1 is specifically: 0.30M citric acid, 0.15M tartaric acid, 0.20M potassium hydrogen tartrate, 0.15M sodium sulfate and 0.05M ferrous sulfate.

[0115] Comparative Example 1

[0116] The difference between this comparative example and Example 1 is as follows:

[0117] After the first electrolytic treatment, the electrolyte is not replaced, and the second electrolytic treatment begins directly.

[0118] Comparative Example 2

[0119] The difference between this comparative example and Example 1 is as follows:

[0120] The first and second reaction solutions both consist of 0.3M citric acid, 0.15M tartaric acid, 0.15M sodium sulfate, and 0.2M potassium hydrogen tartrate.

[0121] Comparative Example 3

[0122] The differences between this comparative example and Example 1 are: (1) The electrochemical system is different. The electrochemical system of this comparative example does not involve the counter electrode isolation chamber 120 separated by the cation exchange membrane 310. Both the counter electrode 220 (platinum mesh) and the working electrode 210 are located in the reaction chamber 110. (2) Buffer solution is not involved.

[0123] Comparative Example 4

[0124] The difference between this comparative example and Example 1 lies in the different potential control: during the first electrolysis treatment, electrolysis was performed at +1.25V for 30 minutes.

[0125] Comparative Example 5

[0126] The difference between this comparative example and Example 1 lies in the different potential control: during the first electrolysis treatment, electrolysis was performed at +0.15V for 30 minutes.

[0127] Comparative Example 6

[0128] The difference between this comparative example and Example 1 lies in the different potential control: during the second electrolysis treatment, electrolysis was performed at -1.35V for 45 minutes.

[0129] Comparative Example 7

[0130] The difference between this comparative example and Example 1 lies in the different potential control: during the second electrolysis treatment, electrolysis was performed at -0.15V for 45 minutes.

[0131] Test case

[0132] Metal concentration tests were conducted on the metal leaching solutions at different stages of the examples and comparative examples. The leaching rate was calculated based on the metal content of the same batch of cathode black powder, and the current efficiency was calculated based on the leaching amount. The test results are shown in Table 2.

[0133] Table 2 Test data for the examples and comparative examples

[0134]

[0135] As shown in Table 2, by comparing the data of Examples 1-6 with those of Comparative Examples 1-3, it can be seen that this application, based on a specific electrochemical system comprising a working electrode 210 formed from positive electrode black powder, successfully constructed an efficient and stable metal leaching pathway by using different electrolytes and supplementing them with staged specific potential control. In contrast, Comparative Example 1 did not change the electrolyte, resulting in the accumulation of impurity ions that poisoned the redox medium (Fe). 2+ / Fe 3+ The cycle of ) caused a sharp drop in the leaching rate of the target metal; Comparative Example 2 lacked the indirect reducing medium (Fe) 2+Due to the large impedance of direct electron transfer between solid and solid, leaching failed directly. In Comparative Example 3, there was no cation exchange membrane 310 and no buffer solution was involved, which caused crosstalk between the reaction chamber 110 and the counter electrode isolation chamber 120. A large amount of hydroxide precipitate coated the electrode, which seriously affected leaching.

[0136] Furthermore, by comparing Examples 1-6 with Comparative Examples 4-7, it can be seen that this application significantly improves the metal leaching rate of the target metal through synergistic potential control, performing a first electrolysis treatment in the range of +0.3V to +0.85V and a second electrolysis treatment in the range of -0.85V to -0.4V. In contrast, the first electrolysis reaction potential of Comparative Example 4 far exceeds the oxygen evolution potential of the system, leading to severe oxygen evolution side reactions. Moreover, the strong anodic oxidation environment may accelerate the formation of a dense passivation film on the surface of the working electrode 210, thereby increasing the charge transfer resistance and hindering the conduction of electrons to the positive electrode black powder. In addition, the citric acid / tartaric acid complexing agent is prone to electrochemical oxidation and bond breaking under strong anodic potential, resulting in a decay of the complexation stability constant and causing some dissolved metal ions to re-hydrolyze and precipitate, further deteriorating the leaching effect. The first electrolysis reaction potential of Comparative Example 5 is too low, resulting in a large number of impurities being carried away with Fe during the second electrolysis stage. 2+ The coexistence of media hinders lattice diffusion and mass transfer, leading to a significant decrease in the leaching rate of the target metal. Therefore, the first electrolytic treatment in this application can create a high-quality, clean reaction interface for the second-stage electrolysis, significantly improving the metal leaching rate.

[0137] Comparative Example 6 suffers from an excessively negative potential in the second electrolysis reaction, leading to a sharp drop in current efficiency and severe hydrogen evolution side reactions. This easily causes secondary hydrolysis and precipitation of the leached Ni, Co, and Mn ions. Although the leaching rate is acceptable, it significantly increases the difficulty and consumption of subsequent separation, and the system stability is poor. Comparative Example 7 suffers from an excessively positive potential in the second electrolysis reaction, resulting in insufficient reduction overpotential and an inability to effectively break lattice bonds, leading to a low metal leaching rate. Therefore, this application, through a specific second electrolysis treatment, can effectively leach the target metal while suppressing side reactions, achieving both high efficiency and stability.

[0138] Furthermore, a comparison of Examples 1-5 and Example 6 reveals that Example 6, employing a constant potential strategy throughout the second electrolysis stage, exhibits lower Ni, Co, and Mn leaching rates and current efficiency compared to Example 1, which utilizes segmented potential control. This demonstrates that employing segmented third and fourth electrolysis stages in the second electrolysis process, with pre-electrolysis at -0.6V to -0.4V, helps reduce concentration polarization at the interface, thereby further improving the leaching rate of the target metal.

[0139] In summary, this application, based on a specific electrochemical system comprising a working electrode 210 formed from positive electrode black powder, successfully constructed an efficient and stable metal leaching pathway by using different electrolytic reaction solutions and supplementing them with staged specific potential control. Furthermore, the above treatment method does not require strong reducing agents or strong acids, and Fe... 2+ The reducing medium is oxidized to Fe 3+ It can be restored and recycled, and has the advantages of being green, environmentally friendly and economically efficient. In addition, the above treatment method has strong compatibility with the raw materials of positive electrode black powder. There is no need to carry out complicated pretreatment and impurity removal processes for positive electrode black powder. Positive electrode black powder mixed with a small amount of negative electrode graphite black powder, positive electrode current collector aluminum foil fragments or conductive carbon copper particles can be used directly as raw materials.

[0140] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0141] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this invention patent should be determined by the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. An electrochemical system for recycling metals from waste ternary lithium batteries, characterized in that, It includes a reaction chamber, a counter-polarity isolation chamber, and a reference monitoring chamber. The reaction chamber and the counter-polarity isolation chamber are separated by a cation exchange membrane, and the reaction chamber is connected to the reference monitoring chamber by a salt bridge. The reaction chamber is equipped with a working electrode, the counter electrode isolation chamber is equipped with a counter electrode, and the reference monitoring chamber is equipped with a reference electrode. The working electrode, the counter electrode, and the reference electrode are connected to a potential controller. The material of the working electrode includes the positive electrode black powder of waste ternary lithium batteries.

2. The electrochemical system for recycling metals from waste ternary lithium batteries according to claim 1, characterized in that, The method for preparing the working electrode includes: Dismantle, crush, and screen waste ternary lithium batteries to obtain positive electrode black powder; Polytetrafluoroethylene (PTFE) is mixed and sheared with the positive electrode black powder to form a fibrillated electrode mixture, wherein the mass ratio of PTFE to the positive electrode black powder is 1:(5~9). The fibrillated electrode mixture is rolled onto the current collector, forming a pre-compression layer of 0.3 mm to 0.6 mm on at least a portion of the surface of the current collector. The pre-compression layer is then hot-pressed and dried to form the working electrode.

3. The electrochemical system for recycling metals from waste ternary lithium batteries according to claim 2, characterized in that, The hot pressing process satisfies one or more of the following (1) to (3): (1) The temperature of hot pressing is 90℃~100℃; (2) The pressure for hot pressing is 5MPa~10MPa; (3) The hot pressing time is 3 min to 5 min.

4. The electrochemical system for recovering metals from waste ternary lithium batteries according to any one of claims 1 to 3, characterized in that, The reaction chamber is also equipped with an ion-selective electrode.

5. A method for recovering metals from waste ternary lithium batteries, characterized in that, The electrochemical system according to any one of claims 1 to 4 comprises the following steps: The first reaction solution is loaded in the reaction chamber, the buffer solution is loaded in the counter electrode isolation chamber, and the electrolyte solution is loaded in the reference monitoring chamber. The working electrode is controlled to perform the first electrolysis treatment in the range of +0.3V to +0.85V. Empty the solution in the reaction chamber, fill the reaction chamber with a second reaction solution, control the working electrode to perform a second electrolysis treatment in the range of -0.85V to -0.4V, collect the solution in the reaction chamber, and obtain the leachate; The first reaction solution comprises sulfate, citric acid, and tartaric acid, and contains citrate or hydrogen tartrate; the second reaction solution comprises sulfate, Fe... 2+ - Tartaric acid complex, citric acid and tartaric acid, and contains citrate or hydrogen tartrate.

6. The method for recovering metals from waste ternary lithium batteries according to claim 5, characterized in that, The second electrolysis process includes the following steps: The working electrode is controlled to perform the third electrolysis at -0.6V to -0.4V; The working electrode is controlled to perform a fourth electrolysis at -0.85V to -0.6V, wherein the potential of the third electrolysis is positive than the potential of the fourth electrolysis.

7. The method for recovering metals from waste ternary lithium batteries according to claim 5, characterized in that, The first reaction solution includes 0.25M~0.35M citric acid, 0.12M~0.2M tartaric acid and 0.1M~0.2M sulfate, and the first reaction solution also includes one of 0.15M~0.3M citrate or 0.15M~0.3M hydrogen tartrate.

8. The method for recovering metals from waste ternary lithium batteries according to claim 5, characterized in that, The buffer solution includes citric acid, sodium citrate, and sodium sulfate.

9. The method for recovering metals from waste ternary lithium batteries according to claim 5, characterized in that, The electrolyte solution includes potassium chloride and potassium citrate.

10. The method for recovering metals from waste ternary lithium batteries according to any one of claims 6 to 9, characterized in that, The method for preparing the second reaction solution includes: Use the first reaction solution as the base solution; Add 0.04M~0.06M of soluble ferrous salt to the base solution and continue mixing and stirring to obtain the second reaction solution.

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