Method for repairing and recycling waste lithium battery positive electrode material

Abstract

The application discloses a kind of repair and recycling method of waste lithium battery positive electrode material, waste lithium battery positive electrode material is repaired by electrochemical repair combined with microwave high-temperature sintering, can effectively restore LiCoO2 Crystal structure in positive electrode material, so that it realizes recycling, the method of the present application has low working voltage, consumes energy, reaction speed is fast, no secondary pollution is generated, and is suitable for large-scale popularization.

Description

Technical Field

[0001] This invention belongs to the field of waste battery recycling technology, specifically relating to a method for repairing the positive electrode material of waste lithium batteries. Background Technology

[0002] Lithium batteries are widely used in electric vehicles and various electronic devices due to their advantages such as small size, light weight, no self-discharge, low pollution, high energy and high operating voltage. As these industries continue to develop, the output of waste lithium batteries is also increasing year by year.

[0003] Waste lithium batteries generally consist of positive electrode materials, negative electrode materials, a casing, a separator, and an electrolyte. The positive electrode material includes a conductive agent, a positive electrode active material, and a binder. The positive electrode active material is often a transition metal oxide such as lithium nickel cobalt manganese oxide, lithium carbonate, or lithium cobalt oxide. The negative electrode material is often graphite and a binder. The positive electrode active material is rich in metals such as nickel, cobalt, manganese, and lithium, thus possessing high recycling value. This is especially true for waste lithium batteries using LiCoO2 as the positive electrode active material, which possess both resource and pollution attributes.

[0004] Currently, the main method for treating spent lithium-ion batteries using LiCoO2 as the positive electrode active material is to recover valuable metals from the positive electrode material. The main methods include dry metallurgy, hydrometallurgy, and biometallurgy, but all require crushing the positive electrode material and involve pollution problems during the process. For example, dry metallurgy generates a large amount of waste gas, and incomplete combustion affects the recovery of valuable metals; hydrometallurgy requires acid leaching of the crushed positive electrode material, thus raising questions about how to improve the leaching of valuable metals and how to treat the subsequent leaching waste liquid; and biometallurgy suffers from difficulties in microbial cultivation, long cultivation cycles, and slow leaching rates. In short, existing recycling methods generally suffer from high costs and cannot fully recycle spent lithium-ion batteries.

[0005] Besides recycling valuable metals from spent lithium batteries, direct regeneration of cathode materials from spent lithium batteries is also a current research hotspot. For example, the solid-state method directly regenerates cathode materials by ball milling cathode materials removed from spent lithium batteries with a lithium source, followed by calcination at 900℃ for 12 hours. However, this method consumes a huge amount of energy and has poor economic efficiency. The molten salt method requires different eutectic molten salt systems to regenerate spent cathode materials. This method requires strict control over the amount of lithium salt used as the lithium source and the reaction time during regeneration, and also needs to address different failure rates. The different applicability of LiCoO2 cathode materials makes this method, with its high requirements, somewhat limiting its application. The hydrothermal method involves placing the depleted LiCoO2 cathode material and a lithium source solution together in a hydrothermal reactor to replenish lithium, followed by annealing to regenerate the cathode material. This method requires high pressure for lithium replenishment, posing a certain risk, and the subsequent annealing process also suffers from high energy consumption. While the eutectic solvent method is carried out at atmospheric pressure, it requires structural damage to the cathode material, necessitating resynthesis after regeneration, resulting in a cumbersome process and low economic efficiency. Therefore, a new method is urgently needed to recycle and reuse spent lithium batteries using LiCoO2 as the cathode active material. Summary of the Invention

[0006] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0007] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0008] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a method for repairing waste lithium battery cathode materials.

[0009] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0010] Waste lithium batteries are disassembled and separated after being discharged to obtain waste LiCoO2 positive electrode sheets;

[0011] Using waste LiCoO2 positive electrode as the negative electrode, platinum plate or activated carbon as the positive electrode, and Ag / AgCl saturated with KCl as the reference electrode, the electrode is rich in Li. + The solution was used as the lithium source solution, and each electrode was immersed in the lithium source solution. An external DC current and a control potential were used as an electrochemical workstation to build an electrochemical repair device.

[0012] Start the electrochemical workstation to perform electrochemical repair. Once the cathode potential is stable, remove the waste LiCoO2 positive electrode sheet and place it in a microwave sintering furnace for high-temperature sintering. After the sintering is complete, remove the electrode sheet and scrape the LiCoO2 positive electrode material off the electrode sheet to obtain the repaired LiCoO2 positive electrode material.

[0013] As a preferred embodiment of the repair method for the cathode material of the waste lithium battery described in this invention, wherein the waste lithium battery has fully reached its service life.

[0014] As a preferred embodiment of the method for repairing the cathode material of waste lithium batteries described in this invention, the electrochemical repair device has a spacing of 5 to 10 cm between the positive and negative electrodes, and a potential of -1.2 V to 1.2 V between the reference electrode and the cathode.

[0015] As a preferred embodiment of the method for repairing waste lithium battery cathode materials according to the present invention, the lithium source solution includes one of Li2SO4 solution, LiCl solution and LiNO3 solution.

[0016] In a preferred embodiment of the method for repairing waste lithium battery cathode materials according to the present invention, the concentration of the lithium source solution is 0.5–2 mol / L.

[0017] In a preferred embodiment of the method for repairing waste lithium battery cathode materials described in this invention, the pH value of the lithium source solution is 5 to 7.

[0018] In a preferred embodiment of the method for repairing the cathode material of spent lithium batteries according to the present invention, the electrochemical repair method includes a cathode current density of -0.1 to -1 mA / cm². 2 .

[0019] As a preferred embodiment of the method for repairing waste lithium battery cathode materials according to the present invention, the high-temperature sintering temperature is 400-800℃ and the sintering time is 0.5-2h.

[0020] Another objective of this invention is to overcome the shortcomings of the prior art and provide a method for reusing waste lithium battery cathode materials.

[0021] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0022] The reuse of waste lithium battery cathode materials obtained through repair methods includes...

[0023] Using carbon black as a conductive agent and polytetrafluoroethylene as a binder, the recycled lithium battery cathode material obtained from the repair process is pressed into electrodes again and used to prepare lithium batteries.

[0024] As a preferred embodiment of the method for reusing waste lithium battery cathode material described in this invention, the recycled lithium battery cathode material, used as the cathode material in the preparation of a lithium battery, retains a capacity of over 90% after 200 charge-discharge cycles.

[0025] Beneficial effects of this invention:

[0026] (1) This invention utilizes the electric field force under a DC electric field to cause the Li in the lithium source solution to... + It can be embedded into the layered crystal structure of the cathode material LiCoO2. Compared with existing regeneration methods such as eutectic solvent method and solid phase method, the present invention does not require the cathode material to be crushed or leached, and can be directly regenerated on the original basis, reducing resource waste.

[0027] (2) Compared with other high-temperature repair methods such as annealing and high-temperature calcination, the microwave high-temperature sintering method used in this invention has a faster heating speed. Under the premise that the present invention has already achieved electrochemical lithium replenishment, microwave sintering is used to restore the LiCoO2 crystal structure in a shorter time and with less energy consumption. At the same time, it can remove the Li adsorbed on the LiCoO2 surface during the lithium replenishment process. + With water of crystallization.

[0028] (3) This invention repairs waste lithium battery cathode materials by combining electrochemical repair with microwave high-temperature sintering, which can effectively restore the LiCoO2 crystal structure in the cathode material. The resulting crystals are small and have a smoother surface. They have the advantages of low working voltage, low energy consumption, fast reaction speed, and no secondary pollution. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0030] Figure 1 This is a schematic diagram of the electrochemical repair device of the present invention. Detailed Implementation

[0031] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0032] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0033] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0034] Unless otherwise specified, all raw materials used in this invention are commercially available.

[0035] The microwave sintering furnace used in this invention is model ANKS-G13.

[0036] Example 1

[0037] The waste lithium batteries were soaked in salt water to discharge them. The discharged waste lithium batteries were then manually disassembled to obtain waste LiCoO2 positive electrode sheets.

[0038] Waste LiCoO2 positive electrode sheet was used as the negative electrode, a platinum plate as the positive electrode, and Ag / AgCl saturated with KCl as the reference electrode. A 0.5 mol / L LiNO3 solution with a pH of 5 was used as the Li-providing electrode. + The lithium source solution is used, and each electrode is immersed in the lithium source solution. An external electrochemical workstation provides DC power and controls the potential.

[0039] Start the electrochemical workstation and control the cathode current density to -0.1 mA / cm². 2 Electrochemical repair was performed. After the cathode potential stabilized, the waste LiCoO2 positive electrode sheet was removed and placed in an ANKS-G13 microwave sintering furnace for high-temperature sintering. The microwave high-temperature sintering temperature was 400℃ and the sintering time was 0.5h. After the sintering was completed, the electrode sheet was removed and the LiCoO2 positive electrode material was scraped off the electrode sheet to obtain the repaired LiCoO2 positive electrode material.

[0040] Example 2

[0041] The waste lithium batteries were soaked in salt water to discharge them. The discharged waste lithium batteries were then manually disassembled to obtain waste LiCoO2 positive electrode sheets.

[0042] Waste LiCoO2 positive electrode sheet was used as the negative electrode, a platinum plate as the positive electrode, and Ag / AgCl saturated with KCl as the reference electrode. A 0.5 mol / L Li2SO4 solution with a pH of 5 was used as the Li-providing electrode.+ The lithium source solution is used, and each electrode is immersed in the lithium source solution. An external electrochemical workstation provides DC power and controls the potential.

[0043] Start the electrochemical workstation and control the cathode current density to -0.1 mA / cm². 2 Electrochemical repair was performed. After the cathode potential stabilized, the waste LiCoO2 positive electrode sheet was removed and placed in an ANKS-G13 microwave sintering furnace for high-temperature sintering. The microwave high-temperature sintering temperature was 400℃ and the sintering time was 0.5h. After the sintering was completed, the electrode sheet was removed and the LiCoO2 positive electrode material was scraped off the electrode sheet to obtain the repaired LiCoO2 positive electrode material.

[0044] Example 3

[0045] The waste lithium batteries were soaked in salt water to discharge them. The discharged waste lithium batteries were then manually disassembled to obtain waste LiCoO2 positive electrode sheets.

[0046] Waste LiCoO2 positive electrode sheet was used as the negative electrode, a platinum plate as the positive electrode, and Ag / AgCl saturated with KCl as the reference electrode. A 0.5 mol / L LiCl solution with a pH of 5 was used as the Li-providing electrode. + The lithium source solution is used, and each electrode is immersed in the lithium source solution. An external electrochemical workstation provides DC power and controls the potential.

[0047] Start the electrochemical workstation and control the cathode current density to -0.1 mA / cm². 2 Electrochemical repair was performed. After the cathode potential stabilized, the waste LiCoO2 positive electrode sheet was removed and placed in an ANKS-G13 microwave sintering furnace for high-temperature sintering. The microwave high-temperature sintering temperature was 400℃ and the sintering time was 0.5h. After the sintering was completed, the electrode sheet was removed and the LiCoO2 positive electrode material was scraped off the electrode sheet to obtain the repaired LiCoO2 positive electrode material.

[0048] The LiCoO2 cathode materials obtained in Examples 1-3 above were used again to prepare lithium batteries:

[0049] Using carbon black as a conductive agent and polytetrafluoroethylene as a binder, the electrode is remade into an electrode by pressing the recycled lithium battery cathode material obtained from the repair process.

[0050] A simulated battery was fabricated using an electrode made from recycled LiCoO2 cathode material as the positive electrode, graphite as the negative electrode, 1 mol / L LiPF6 / ethylene carbonate (EC) + diethyl carbonate (DEC) + methyl ethyl carbonate (EMC) as the electrolyte, and a Celgard 2400 membrane as the separator.

[0051] The batteries prepared in each embodiment were tested, and the measured indicators were the specific capacity of the first charge at 0.5C rate, the specific capacity of the discharge, and the capacity retention rate after 200 charge-discharge cycles. The results are shown in Table 1.

[0052] Table 1 Performance of cathode materials prepared with different lithium source solutions as cathodes for regenerative batteries

[0053]

[0054] As can be seen from Table 1, in the present invention, the cathode material obtained by solution repair using LiNO3 as the lithium source performs better as the cathode of the regenerated battery. This is because when using LiNO3 solution as the lithium source, during the regeneration process, Li... + The electron migration impedance is low, making it easier to fill the vacancies in LiCoO2 material. Therefore, in the following examples, LiNO3 solution was selected as the solution to provide the lithium source.

[0055] Example 4

[0056] The waste lithium batteries were soaked in salt water to discharge them. The discharged waste lithium batteries were then manually disassembled to obtain waste LiCoO2 positive electrode sheets.

[0057] Waste LiCoO2 positive electrode sheet was used as the negative electrode, a platinum plate as the positive electrode, and Ag / AgCl saturated with KCl as the reference electrode. A 0.5 mol / L LiNO3 solution with a pH of 6 was used as the Li-providing electrode. + The lithium source solution is used, and each electrode is immersed in the lithium source solution. An external electrochemical workstation provides DC power and controls the potential.

[0058] Start the electrochemical workstation and control the cathode current density to -0.1 mA / cm². 2 Electrochemical repair was performed. After the cathode potential stabilized, the waste LiCoO2 positive electrode sheet was removed and placed in an ANKS-G13 microwave sintering furnace for high-temperature sintering. The microwave high-temperature sintering temperature was 400℃ and the sintering time was 0.5h. After the sintering was completed, the electrode sheet was removed and the LiCoO2 positive electrode material was scraped off the electrode sheet to obtain the repaired LiCoO2 positive electrode material.

[0059] Example 5

[0060] Waste LiCoO2 positive electrode sheet was used as the negative electrode, a platinum plate as the positive electrode, and Ag / AgCl saturated with KCl as the reference electrode. A 0.5 mol / L LiNO3 solution with a pH of 7 was used as the Li-providing electrode. + The lithium source solution is used, and each electrode is immersed in the lithium source solution. An external electrochemical workstation provides DC power and controls the potential.

[0061] Start the electrochemical workstation and control the cathode current density to -0.1 mA / cm². 2 Electrochemical repair was performed. After the cathode potential stabilized, the waste LiCoO2 positive electrode sheet was removed and placed in an ANKS-G13 microwave sintering furnace for high-temperature sintering. The microwave high-temperature sintering temperature was 400℃ and the sintering time was 0.5h. After the sintering was completed, the electrode sheet was removed and the LiCoO2 positive electrode material was scraped off the electrode sheet to obtain the repaired LiCoO2 positive electrode material.

[0062] The LiCoO2 cathode materials obtained in Examples 1, 4-5 above were used again to prepare lithium batteries:

[0063] Using carbon black as a conductive agent and polytetrafluoroethylene as a binder, the electrode is remade into an electrode by pressing the recycled lithium battery cathode material obtained from the repair process.

[0064] A simulated battery was fabricated using an electrode made from recycled LiCoO2 cathode material as the positive electrode, graphite as the negative electrode, 1 mol / L LiPF6 / ethylene carbonate (EC) + diethyl carbonate (DEC) + methyl ethyl carbonate (EMC) as the electrolyte, and a Celgard 2400 membrane as the separator.

[0065] The batteries prepared in each embodiment were tested, and the measured indicators were the specific capacity of the first charge at 0.5C rate, the specific capacity of the discharge, and the capacity retention rate after 200 charge-discharge cycles. The results are shown in Table 2.

[0066] Table 2 Performance of cathode materials prepared at different solution pH levels as cathodes for regenerative batteries

[0067]

[0068] As can be seen from Table 2, in the present invention, the cathode material obtained by repairing the solution at pH 6 performs better as a cathode for regenerated batteries. This is because OH- ions are generated when the pH of the lithium source solution is too high or too low. - or H + This affects the regeneration of the cathode material. Therefore, the pH of the solution in the following examples is selected to be 6.

[0069] Example 6

[0070] The waste lithium batteries were soaked in salt water to discharge them. The discharged waste lithium batteries were then manually disassembled to obtain waste LiCoO2 positive electrode sheets.

[0071] Waste LiCoO2 positive electrode sheet was used as the negative electrode, a platinum plate as the positive electrode, and Ag / AgCl saturated with KCl as the reference electrode. A 1.3 mol / L LiNO3 solution with a pH of 6 was used as the Li-providing electrode. +The lithium source solution is used, and each electrode is immersed in the lithium source solution. An external electrochemical workstation provides DC power and controls the potential.

[0072] Start the electrochemical workstation and control the cathode current density to -0.1 mA / cm². 2 Electrochemical repair was performed. After the cathode potential stabilized, the waste LiCoO2 positive electrode sheet was removed and placed in an ANKS-G13 microwave sintering furnace for high-temperature sintering. The microwave high-temperature sintering temperature was 400℃ and the sintering time was 0.5h. After the sintering was completed, the electrode sheet was removed and the LiCoO2 positive electrode material was scraped off the electrode sheet to obtain the repaired LiCoO2 positive electrode material.

[0073] Example 7

[0074] The waste lithium batteries were soaked in salt water to discharge them. The discharged waste lithium batteries were then manually disassembled to obtain waste LiCoO2 positive electrode sheets.

[0075] Waste LiCoO2 positive electrode sheet was used as negative electrode, platinum plate as positive electrode, saturated KCl Ag / AgCl as reference electrode, and LiNO3 solution with a concentration of 2 mol / L and a pH of 6 as lithium source solution to provide Li. Each electrode was immersed in the lithium source solution, and an external electrochemical workstation was used to provide DC power and control the potential.

[0076] Start the electrochemical workstation and control the cathode current density to -0.1 mA / cm². 2 Electrochemical repair was performed. After the cathode potential stabilized, the waste LiCoO2 positive electrode sheet was removed and placed in an ANKS-G13 microwave sintering furnace for high-temperature sintering. The microwave high-temperature sintering temperature was 400℃ and the sintering time was 0.5h. After the sintering was completed, the electrode sheet was removed and the LiCoO2 positive electrode material was scraped off the electrode sheet to obtain the repaired LiCoO2 positive electrode material.

[0077] The LiCoO2 cathode materials obtained in Examples 4, 6-7 above were used again to prepare lithium batteries:

[0078] Using carbon black as a conductive agent and polytetrafluoroethylene as a binder, the electrode is remade into an electrode by pressing the recycled lithium battery cathode material obtained from the repair process.

[0079] A simulated battery was fabricated using an electrode made from recycled LiCoO2 cathode material as the positive electrode, graphite as the negative electrode, 1 mol / L LiPF6 / ethylene carbonate (EC) + diethyl carbonate (DEC) + methyl ethyl carbonate (EMC) as the electrolyte, and a Celgard 2400 membrane as the separator.

[0080] The batteries prepared in each embodiment were tested, and the measured indicators were the specific capacity of the first charge at 0.5C rate, the specific capacity of the discharge, and the capacity retention rate after 200 charge-discharge cycles. The results are shown in Table 3.

[0081] Table 3 Performance of cathode materials prepared with different solution concentrations as cathodes for regenerative batteries

[0082]

[0083] As shown in Table 3, in the present invention, the cathode material obtained by repairing the solution with a concentration of 1.3 mol / L performs better as a cathode for regenerated batteries. This is because when the solution concentration is high, excessive anions may remain stably near the cathode electrode, affecting the Li... + The migration of Li, and when the solution concentration is low, the Li contained... + A lower concentration will also affect the regeneration of the cathode material. Therefore, the following examples selected a solution concentration of 1.3 mol / L.

[0084] Example 8

[0085] The waste lithium batteries were soaked in salt water to discharge them. The discharged waste lithium batteries were then manually disassembled to obtain waste LiCoO2 positive electrode sheets.

[0086] Waste LiCoO2 positive electrode sheet was used as the negative electrode, a platinum plate as the positive electrode, and Ag / AgCl saturated with KCl as the reference electrode. A 1.3 mol / L LiNO3 solution with a pH of 6 was used as the Li-providing electrode. + The lithium source solution is used, and each electrode is immersed in the lithium source solution. An external electrochemical workstation provides DC power and controls the potential.

[0087] Start the electrochemical workstation and control the cathode current density to -0.5 mA / cm². 2 Electrochemical repair was performed. After the cathode potential stabilized, the waste LiCoO2 positive electrode sheet was removed and placed in an ANKS-G13 microwave sintering furnace for high-temperature sintering. The microwave high-temperature sintering temperature was 400℃ and the sintering time was 0.5h. After the sintering was completed, the electrode sheet was removed and the LiCoO2 positive electrode material was scraped off the electrode sheet to obtain the repaired LiCoO2 positive electrode material.

[0088] Example 9

[0089] The waste lithium batteries were soaked in salt water to discharge them. The discharged waste lithium batteries were then manually disassembled to obtain waste LiCoO2 positive electrode sheets.

[0090] Waste LiCoO2 positive electrode sheet was used as the negative electrode, a platinum plate as the positive electrode, and Ag / AgCl saturated with KCl as the reference electrode. A 1.3 mol / L LiNO3 solution with a pH of 6 was used as the Li-providing electrode. + The lithium source solution is used, and each electrode is immersed in the lithium source solution. An external electrochemical workstation provides DC power and controls the potential.

[0091] Start the electrochemical workstation and control the cathode current density to -1 mA / cm². 2 Electrochemical repair was performed. After the cathode potential stabilized, the waste LiCoO2 positive electrode sheet was removed and placed in an ANKS-G13 microwave sintering furnace for high-temperature sintering. The microwave high-temperature sintering temperature was 400℃ and the sintering time was 0.5h. After the sintering was completed, the electrode sheet was removed and the LiCoO2 positive electrode material was scraped off the electrode sheet to obtain the repaired LiCoO2 positive electrode material.

[0092] The LiCoO2 cathode materials obtained in Examples 6, 8-9 above were used again to prepare lithium batteries:

[0093] Using carbon black as a conductive agent and polytetrafluoroethylene as a binder, the electrode is remade into an electrode by pressing the recycled lithium battery cathode material obtained from the repair process.

[0094] A simulated battery was fabricated using an electrode made from recycled LiCoO2 cathode material as the positive electrode, graphite as the negative electrode, 1 mol / L LiPF6 / ethylene carbonate (EC) + diethyl carbonate (DEC) + methyl ethyl carbonate (EMC) as the electrolyte, and a Celgard 2400 membrane as the separator.

[0095] The batteries prepared in each embodiment were tested, and the measured indicators were the specific capacity of the first charge at 0.5C rate, the specific capacity of the discharge, and the capacity retention rate after 200 charge-discharge cycles. The results are shown in Table 4.

[0096] Table 4 Performance of cathode materials prepared at different current densities as cathodes for regenerative batteries

[0097]

[0098]

[0099] As can be seen from Table 4, the current density in the present invention is -0.5 mA / cm². 2 The cathode material obtained through time-repair processes performs better as a cathode for regenerated batteries. This is because the electric field force generated when the cathode current density is low is also low, which affects the Li... +Migration occurs to vacancy sites in the LiCoO2 positive layered structure; however, excessively high current densities may lead to electrolysis, generating gas and affecting the regeneration of the cathode material. Therefore, the following embodiments select a current density of -0.5 mA / cm². 2 .

[0100] Example 10

[0101] The waste lithium batteries were soaked in salt water to discharge them. The discharged waste lithium batteries were then manually disassembled to obtain waste LiCoO2 positive electrode sheets.

[0102] Waste LiCoO2 positive electrode sheet was used as the negative electrode, a platinum plate as the positive electrode, and Ag / AgCl saturated with KCl as the reference electrode. A 1.3 mol / L LiNO3 solution with a pH of 6 was used as the Li-providing electrode. + The lithium source solution is used, and each electrode is immersed in the lithium source solution. An external electrochemical workstation provides DC power and controls the potential.

[0103] Start the electrochemical workstation and control the cathode current density to -0.5 mA / cm². 2 Electrochemical repair is then performed. After the cathode potential stabilizes, the waste LiCoO2 positive electrode sheet is removed and placed in an ANKS-G13 microwave sintering furnace for high-temperature sintering. The microwave high-temperature sintering temperature is 400℃ and the sintering time is 2 hours. After the sintering is completed, the electrode sheet is removed and the LiCoO2 positive electrode material is scraped off the electrode sheet to obtain the repaired LiCoO2 positive electrode material.

[0104] Example 11

[0105] The waste lithium batteries were soaked in salt water to discharge them. The discharged waste lithium batteries were then manually disassembled to obtain waste LiCoO2 positive electrode sheets.

[0106] Waste LiCoO2 positive electrode sheet was used as the negative electrode, a platinum plate as the positive electrode, and Ag / AgCl saturated with KCl as the reference electrode. A 1.3 mol / L LiNO3 solution with a pH of 6 was used as the Li-providing electrode. + The lithium source solution is used, and each electrode is immersed in the lithium source solution. An external electrochemical workstation provides DC power and controls the potential.

[0107] Start the electrochemical workstation and control the cathode current density to -0.5 mA / cm². 2 Electrochemical repair is then performed. After the cathode potential stabilizes, the waste LiCoO2 positive electrode sheet is removed and placed in an ANKS-G13 microwave sintering furnace for high-temperature sintering. The microwave high-temperature sintering temperature is 600℃ and the sintering time is 2 hours. After the sintering is completed, the electrode sheet is removed and the LiCoO2 positive electrode material is scraped off the electrode sheet to obtain the repaired LiCoO2 positive electrode material.

[0108] Example 12

[0109] The waste lithium batteries were soaked in salt water to discharge them. The discharged waste lithium batteries were then manually disassembled to obtain waste LiCoO2 positive electrode sheets.

[0110] Waste LiCoO2 positive electrode sheet was used as the negative electrode, a platinum plate as the positive electrode, and Ag / AgCl saturated with KCl as the reference electrode. A 1.3 mol / L LiNO3 solution with a pH of 6 was used as the Li-providing electrode. + The lithium source solution is used, and each electrode is immersed in the lithium source solution. An external electrochemical workstation provides DC power and controls the potential.

[0111] Start the electrochemical workstation and control the cathode current density to -0.5 mA / cm². 2 Electrochemical repair is then performed. After the cathode potential stabilizes, the waste LiCoO2 positive electrode sheet is removed and placed in an ANKS-G13 microwave sintering furnace for high-temperature sintering. The microwave high-temperature sintering temperature is 800℃ and the sintering time is 2 hours. After the sintering is completed, the electrode sheet is removed and the LiCoO2 positive electrode material is scraped off the electrode sheet to obtain the repaired LiCoO2 positive electrode material.

[0112] The LiCoO2 cathode materials obtained in Examples 10-12 above were used again to prepare lithium batteries:

[0113] Using carbon black as a conductive agent and polytetrafluoroethylene as a binder, the electrode is remade into an electrode by pressing the recycled lithium battery cathode material obtained from the repair process.

[0114] A simulated battery was fabricated using an electrode made from recycled LiCoO2 cathode material as the positive electrode, graphite as the negative electrode, 1 mol / L LiPF6 / ethylene carbonate (EC) + diethyl carbonate (DEC) + methyl ethyl carbonate (EMC) as the electrolyte, and a Celgard 2400 membrane as the separator.

[0115] The batteries prepared in each embodiment were tested, and the measured indicators were the specific capacity of the first charge at 0.5C rate, the specific capacity of the discharge, and the capacity retention rate after 200 charge-discharge cycles. The results are shown in Table 5.

[0116] Table 5 Performance of cathode materials prepared at different sintering temperatures as cathodes for regenerative batteries

[0117]

[0118] As can be seen from Table 5, in the present invention, the cathode material repaired at a sintering temperature of 600℃ performs better as the cathode of the regenerated battery. This is because when the sintering temperature is too low, the crystal structure of the LiCoO2 material cannot be fully restored, resulting in the cathode material not being fully regenerated; while when the sintering temperature is too high, the binder on the original LiCoO2 electrode will carbonize, affecting the performance of the regenerated material.

[0119] As can be seen from the above embodiments, the present invention can effectively restore the LiCoO2 crystal structure in the cathode material by electrochemical repair combined with microwave high-temperature sintering, thereby enabling its recycling.

[0120] This invention utilizes the electric field force under a DC electric field to cause the Li in the lithium source solution to... + It can be embedded into the layered crystal structure of the cathode material LiCoO2. Compared with existing regeneration methods such as eutectic solvent method and solid phase method, the present invention does not require the cathode material to be crushed or leached, and can be directly regenerated on the original basis, reducing resource waste.

[0121] Compared to other high-temperature repair methods such as annealing and high-temperature calcination, the microwave high-temperature sintering method used in this invention has a faster heating speed. Given that electrochemical lithium replenishment has already been performed in this invention, microwave sintering for restoring the LiCoO2 crystal structure requires less time and consumes less energy. Simultaneously, it can remove Li adsorbed on the LiCoO2 surface during the lithium replenishment process. + With water of crystallization.

[0122] The method of this invention has low operating voltage, low energy consumption, fast reaction speed, and no secondary pollution, making it suitable for large-scale promotion.

[0123] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for repairing waste lithium battery cathode materials, characterized in that: include, Waste lithium batteries are disassembled and separated after being discharged to obtain waste LiCoO2 positive electrode sheets; Using waste LiCoO2 positive electrode as the negative electrode, platinum plate or activated carbon as the positive electrode, and Ag / AgCl saturated with KCl as the reference electrode, the electrode is rich in Li. + Using the solution as the lithium source solution, each electrode is immersed in the LiNO3 solution, and an external DC current and a control potential are applied as an electrochemical workstation to build an electrochemical repair device. The electrochemical workstation is started to carry out electrochemical repair. After the cathode potential stabilizes, the waste LiCoO2 positive electrode sheet is removed and placed in a microwave sintering furnace for high-temperature sintering at 600℃ for 0.5h. After the sintering is completed, the electrode sheet is removed and the LiCoO2 positive electrode material is scraped off the electrode sheet to obtain the repaired LiCoO2 positive electrode material.

2. The method for repairing waste lithium battery cathode materials as described in claim 1, characterized in that: The used lithium batteries have reached the end of their service life.

3. The method for repairing waste lithium battery cathode materials as described in claim 1, characterized in that: In the electrochemical repair device, the distance between the positive and negative electrodes is 5~10cm, and the potential between the reference electrode and the cathode is -1.2V~1.2V.

4. The method for repairing waste lithium battery cathode materials as described in claim 1, characterized in that: The concentration of the lithium source solution is 0.5~2 mol / L.

5. The method for repairing waste lithium battery cathode materials as described in claim 4, characterized in that: The pH value of the lithium source solution is 5-7.

6. The method for repairing waste lithium battery cathode materials as described in any one of claims 1 or 3, characterized in that: In the electrochemical remediation, the cathode current density is -0.1 to -1 mA / cm². 2 .

7. A method for reusing waste lithium battery cathode materials, characterized in that: The method for repairing waste lithium battery cathode materials as described in any one of claims 1 to 6 further includes, Using carbon black as a conductive agent and polytetrafluoroethylene as a binder, the recycled lithium battery cathode material obtained from the repair process is pressed into electrodes again and used to prepare lithium batteries.

8. The method for reusing waste lithium battery cathode materials as described in claim 7, characterized in that: The lithium battery prepared using the recycled lithium battery cathode material as the cathode has a capacity retention rate of over 90% after 200 charge-discharge cycles.

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