Method for separating positive and negative electrode powders

Abstract

The application discloses a positive and negative electrode powder separation method, which comprises the following steps: S1, crushing, drying and air selecting a waste ternary lithium battery to remove the shell and diaphragm to obtain a mixture; S2, calcining the mixture in an inert gas atmosphere, and then magnetically selecting the magnetic substance and the non-magnetic substance; S3, separating the magnetic substance by wet stripping to separate the positive electrode foil and the positive electrode powder, and separating the non-magnetic substance by wet stripping to separate the negative electrode foil and the negative electrode powder; S4, dissolving the positive electrode powder in solution A, adding nickel sulfate, cobalt sulfate and manganese sulfate to uniformly mix to obtain solution B, then uniformly mixing solution B with a sodium carbonate aqueous solution, adjusting the pH to 8-8.5 by using ammonia water, carrying out a hydrothermal reaction, and collecting the precipitate; uniformly mixing the precipitate with lithium carbonate and zirconium hydroxide, primary sintering, and obtaining intermediate materials; then uniformly mixing the intermediate materials with ammonium molybdate tetrahydrate, secondary sintering, and obtaining a modified positive electrode material.

Description

A method for separating positive and negative electrode powders Technical Field

[0001] This invention relates to the field of battery recycling technology, and in particular to a method for separating positive and negative electrode powders. Background Technology

[0002] Lithium-ion batteries hold a vital position in the domestic and international new energy and related application fields. They are primarily used in electronic devices such as tablets, smartphones, and cameras, and also play a crucial role in energy storage applications including new energy vehicles, power storage, and backup power for communication base stations. Compared to traditional materials, ternary cathode materials offer higher energy density, better cycle performance, and greater specific capacity, resulting in longer battery life for the same volume and weight, and thus higher recycling and application value.

[0003] Currently, the recycling of ternary lithium batteries mainly involves crushing, low-temperature pyrolysis, and high-temperature carbonization of the waste batteries, ultimately producing a mixture of positive and negative electrode black powder as the final product. However, the positive and negative electrode materials still need further separation, which increases the difficulty of subsequent hydrometallurgical extraction of valuable components and increases pollutant emissions. Summary of the Invention

[0004] Based on the technical problems existing in the background technology, the present invention proposes a method for separating positive and negative electrode powders. The method of the present invention is simple to operate, has little environmental pollution, and can effectively separate positive electrode foils, positive electrode powders, negative electrode foils, and negative electrode powders with a high recovery rate. The obtained positive electrode powder can be directly repaired and modified for reuse. The modified positive electrode material prepared by the present invention has good cycle performance and electrochemical performance.

[0005] This invention proposes a method for separating positive and negative electrode powders, comprising the following steps:

[0006] S1. The waste ternary lithium batteries are crushed, dried, and air-separated to remove the casing and separator to obtain a mixture.

[0007] S2. The mixture is calcined in an inert gas atmosphere, and then magnetic separation is used to separate the magnetic and non-magnetic substances.

[0008] S3. Use wet stripping to separate magnetic materials, thus separating the positive electrode foil and positive electrode powder; use wet stripping to separate non-magnetic materials, thus separating the negative electrode foil and negative electrode powder.

[0009] S4. Dissolve the cathode powder in solution A, add nickel sulfate, cobalt sulfate and manganese sulfate and mix well to obtain solution B. Then mix solution B with sodium carbonate aqueous solution, adjust the pH to 8-8.5 with ammonia water, carry out hydrothermal reaction, and collect the precipitate. Mix the precipitate with lithium carbonate and zirconium hydroxide, and sinter once to obtain intermediate material. Then mix the intermediate material with ammonium molybdate tetrahydrate and sinter a second time to obtain modified cathode material.

[0010] Preferably, in S1, the positive electrode material of the waste ternary lithium battery is lithium nickel cobalt manganese oxide.

[0011] Preferably, in S1, the waste ternary lithium batteries are crushed in an inert gas atmosphere.

[0012] Preferably, in S1, the drying temperature is 80-125°C.

[0013] Preferably, in step S1, the waste ternary lithium batteries are crushed while charged to a particle size of 5-8 cm.

[0014] Preferably, in S2, the calcination temperature is 850-1000℃ and the calcination time is 2.5-3.5h.

[0015] Preferably, in S2, the magnetic induction intensity during magnetic separation is 22000-25000 Gauss.

[0016] This invention eliminates the need for discharging spent ternary lithium batteries, reducing water pollution. Calcination in an inert gas atmosphere causes the binder and conductive agent to carbonize and interact with graphite, converting lithium nickel cobalt manganese oxide into magnetic oxide. Magnetic separation then separates the magnetic and non-magnetic components. Finally, wet stripping separates the positive electrode foil, positive electrode powder, negative electrode foil, and negative electrode powder. The process is simple and significantly improves the recovery rate.

[0017] Preferably, in S4, solution A is a mixture of sulfuric acid aqueous solution and hydrogen peroxide aqueous solution.

[0018] Preferably, the concentration of sulfuric acid in solution A is 0.8-1.2 mol / L.

[0019] Preferably, in solution A, the mass fraction of hydrogen peroxide aqueous solution is 28-30 wt%.

[0020] Preferably, the volume ratio of sulfuric acid aqueous solution to hydrogen peroxide aqueous solution is 4.5-5.5:1.

[0021] Preferably, in S4, the total concentration of metal ions in solution B is 1.8-2.2 mol / L.

[0022] Preferably, in S4, the molar ratio of nickel, cobalt, and manganese in solution B is 4-5:2-2.5:3-3.5.

[0023] Preferably, in S4, the concentration of the sodium carbonate aqueous solution is 1.8-2.2 mol / L.

[0024] Preferably, in step S4, solution B is mixed with an equal volume of sodium carbonate aqueous solution.

[0025] Preferably, in S4, the hydrothermal reaction temperature is 55-65℃ and the time is 11-12h.

[0026] Preferably, in S4, the ratio of the total molar number of nickel, cobalt, manganese, and zirconium to the molar number of lithium in the mixture of precipitate and lithium carbonate is 1:1-1.05.

[0027] Preferably, in S4, the ratio of the total number of moles of nickel, cobalt, manganese and zirconium to the number of moles of zirconium is 1:0.001-0.002.

[0028] Preferably, in S4, the sintering procedure is as follows: heat to 450-470℃, hold for 4.5-5.5h, then heat to 830-850℃ and hold for 11-13h.

[0029] Preferably, in S4, a second sintering is performed at 580-620℃ for 2.5-3.5 hours.

[0030] Preferably, in S4, the weight ratio of the intermediate material to ammonium molybdate tetrahydrate is 1:0.01-0.02.

[0031] In addition, this invention involves hydrothermal reaction of cathode powder to form nickel, cobalt, and manganese as precipitate precursors; then sintering with lithium carbonate and zirconium hydroxide to obtain zirconium-doped lithium nickel cobalt manganese oxide, which is then mixed with ammonium molybdate tetrahydrate and sintered to coat its surface with molybdenum trioxide. Through the synergistic effect of zirconium doping and molybdenum trioxide coating, the integrity of the internal lattice of lithium nickel cobalt manganese oxide can be maintained, thus preserving its structural stability. On the other hand, it can improve conductivity, inhibit electrolyte decomposition, and promote lithium ion insertion and extraction, thereby improving its cycle performance and electrochemical performance, and realizing the recycling and reuse of waste ternary cathode materials.

[0032] The method described in this invention is simple to operate, has low environmental pollution, and can effectively separate positive electrode foil, positive electrode powder, negative electrode foil, and negative electrode powder with a high recovery rate. The obtained positive electrode powder can be directly repaired and modified for reuse. The modified positive electrode material prepared by this invention has good cycle performance and electrochemical performance. Detailed Implementation

[0033] The technical solution of the present invention will now be described in detail through specific embodiments.

[0034] Example 1

[0035] A method for separating positive and negative electrode powders includes the following steps:

[0036] S1. Under nitrogen protection, waste nickel-cobalt-manganese lithium ternary lithium batteries are crushed to a particle size of 5cm, dried at 80℃, and then the shell and separator are removed by air classification to obtain a mixture.

[0037] S2. Calcine the mixture at 1000℃ for 2.5h in a nitrogen atmosphere, then adjust the magnetic induction intensity to 25000 Gauss and use a magnetic separator to separate the magnetic and non-magnetic substances.

[0038] S3. Use wet stripping to separate magnetic materials, thus separating the positive electrode foil and positive electrode powder; use wet stripping to separate non-magnetic materials, thus separating the negative electrode foil and negative electrode powder.

[0039] S4. Dissolve the positive electrode powder in solution A (a mixture of 1 mol / L sulfuric acid aqueous solution and 30 wt% hydrogen peroxide aqueous solution in a volume ratio of 4.5:1). Add nickel sulfate, cobalt sulfate, and manganese sulfate and mix well to obtain solution B, such that the total concentration of metal ions in solution B is 2 mol / L, and the molar ratio of nickel, cobalt, and manganese in solution B is 4:2.5:3.5. Then, mix solution B with an equal volume of 2 mol / L sodium carbonate aqueous solution, adjust the pH to 8.5 with ammonia, and perform a hydrothermal reaction at 65℃ for 11 hours. Collect the precipitate. The precipitate was washed with water and dried. Then, the precipitate was ground and mixed with lithium carbonate and zirconium hydroxide so that the molar ratio of the total molar number of nickel, cobalt, manganese and zirconium to the molar number of lithium was 1:1.03, and the molar ratio of the total molar number of nickel, cobalt, manganese and zirconium to the molar number of zirconium was 1:0.002. The temperature was then raised to 470℃ and held for 4.5 h, and then raised to 850℃ and held for 11 h for a first sintering to obtain an intermediate material. The intermediate material was then ground and mixed with ammonium molybdate tetrahydrate at a weight ratio of 1:0.02 and sintered again at 580℃ for 3.5 h to obtain the modified cathode material.

[0040] Example 2

[0041] A method for separating positive and negative electrode powders includes the following steps:

[0042] S1. Under nitrogen protection, waste nickel-cobalt-manganese lithium ternary lithium batteries are crushed to a particle size of 8cm, dried at 125℃, and then the shell and separator are removed by air classification to obtain a mixture.

[0043] S2. Calcine the mixture at 850°C for 3.5 hours in a nitrogen atmosphere, then adjust the magnetic induction intensity to 22,000 Gauss and use a magnetic separator to separate the magnetic and non-magnetic substances.

[0044] S3. Use wet stripping to separate magnetic materials, thus separating the positive electrode foil and positive electrode powder; use wet stripping to separate non-magnetic materials, thus separating the negative electrode foil and negative electrode powder.

[0045] S4. Dissolve the positive electrode powder in solution A (a mixture of 1 mol / L sulfuric acid aqueous solution and 30 wt% hydrogen peroxide aqueous solution in a volume ratio of 5.5:1). Add nickel sulfate, cobalt sulfate, and manganese sulfate and mix well to obtain solution B, such that the total concentration of metal ions in solution B is 2 mol / L, and the molar ratio of nickel, cobalt, and manganese in solution B is 5:2:3. Then, mix solution B with an equal volume of 2 mol / L sodium carbonate aqueous solution, adjust the pH to 8 with ammonia, and perform a hydrothermal reaction at 55℃ for 12 hours. Collect the precipitate. The precipitate was washed and dried. Then, it was ground and mixed with lithium carbonate and zirconium hydroxide so that the total molar ratio of nickel, cobalt, manganese and zirconium to lithium was 1:1, and the total molar ratio of nickel, cobalt, manganese and zirconium to zirconium was 1:0.001. The mixture was then heated to 450℃ and held for 5.5 h, and then heated to 830℃ and held for 13 h for a first sintering to obtain an intermediate material. The intermediate material was then ground and mixed with ammonium molybdate tetrahydrate at a weight ratio of 1:0.01 and sintered again at 620℃ for 2.5 h to obtain the modified cathode material.

[0046] Example 3

[0047] A method for separating positive and negative electrode powders includes the following steps:

[0048] S1. Under nitrogen protection, waste nickel-cobalt-manganese lithium ternary lithium batteries are crushed to a particle size of 7cm, dried at 110℃, and then the shell and separator are removed by air classification to obtain a mixture.

[0049] S2. Calcine the mixture at 950°C for 3 hours in a nitrogen atmosphere, then adjust the magnetic induction intensity to 23,000 Gauss and use a magnetic separator to separate the magnetic and non-magnetic substances.

[0050] S3. Use wet stripping to separate magnetic materials, thus separating the positive electrode foil and positive electrode powder; use wet stripping to separate non-magnetic materials, thus separating the negative electrode foil and negative electrode powder.

[0051] S4. Dissolve the positive electrode powder in solution A (a mixture of 1 mol / L sulfuric acid aqueous solution and 30 wt% hydrogen peroxide aqueous solution in a volume ratio of 5:1). Add nickel sulfate, cobalt sulfate, and manganese sulfate and mix well to obtain solution B, so that the total concentration of metal ions in solution B is 2 mol / L, and the molar ratio of nickel, cobalt, and manganese in solution B is 5:2:3. Then, mix solution B with an equal volume of 2 mol / L sodium carbonate aqueous solution, adjust the pH to 8.5 with ammonia, and perform a hydrothermal reaction at 60℃ for 12 hours. Collect the precipitate. The precipitate was washed and dried. Then, it was ground and mixed with lithium carbonate and zirconium hydroxide to make the ratio of the total molar number of nickel, cobalt, manganese and zirconium to the molar number of lithium 1:1.05, and the ratio of the total molar number of nickel, cobalt, manganese and zirconium to the molar number of zirconium 1:0.002. The temperature was then raised to 460℃ and held for 5 hours, and then raised to 840℃ and held for 12 hours for a first sintering to obtain an intermediate material. The intermediate material was then ground and mixed with ammonium molybdate tetrahydrate at a weight ratio of 1:0.01 and sintered again at 600℃ for 3 hours to obtain the modified cathode material.

[0052] Comparative Example 1

[0053] Take the positive electrode powder obtained in Example 3 and prepare intermediate materials according to the method in S4 of Example 3.

[0054] Comparative Example 2

[0055] Take the cathode powder obtained in Example 3, without adding zirconium hydroxide, and make the total molar ratio of nickel, cobalt, and manganese to lithium 1:1.05. Prepare the modified cathode material according to the method in S4 of Example 3.

[0056] Comparative Example 3

[0057] Take the cathode powder obtained in Example 3, without adding zirconium hydroxide, and make the total molar ratio of nickel, cobalt, and manganese to lithium 1:1.05. Prepare intermediate materials according to the method in S4 of Example 3.

[0058] The materials obtained in Examples 1-3 and Comparative Examples 1-3 were used as cathode materials to prepare coin-type ternary lithium batteries, and their cycle performance and electrochemical performance were tested. The results are shown in Table 1.

[0059] Table 1 Test Results

[0060]

[0061]

[0062] As can be seen from Table 1, the modified cathode material prepared by the method described in this invention has good electrochemical performance and cycle performance.

[0063] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for separating positive and negative electrode powders, characterized in that, The process includes the following steps: S1. Crushing, drying, and air-separating the casing and separator of the waste ternary lithium batteries to obtain a mixture; S2. Calcining the mixture in an inert gas atmosphere, followed by magnetic separation to separate the magnetic and non-magnetic materials; S3. Separating the magnetic materials using wet stripping to separate the positive electrode foil and positive electrode powder; separating the non-magnetic materials using wet stripping to separate the negative electrode foil and negative electrode powder; S4. Dissolving the positive electrode powder in solution A, adding nickel sulfate, cobalt sulfate, and manganese sulfate and mixing to obtain solution B, then mixing solution B with an aqueous sodium carbonate solution, adjusting the pH to 8-8.5 with ammonia, carrying out a hydrothermal reaction, and collecting the precipitate; The precipitate was mixed with lithium carbonate and zirconium hydroxide, and sintered once to obtain an intermediate material. Then, the intermediate material was mixed with ammonium molybdate tetrahydrate and sintered a second time to obtain the modified cathode material. In S4, solution A was a mixture of sulfuric acid aqueous solution and hydrogen peroxide aqueous solution; the concentration of sulfuric acid in solution A was 0.8-1.2 mol / L; the mass fraction of hydrogen peroxide aqueous solution in solution A was 28-30 wt%; the volume ratio of sulfuric acid aqueous solution to hydrogen peroxide aqueous solution was 4.5-5.5:1; in S4, the total concentration of metal ions in solution B was 1.8-2.2 mol / L; in S4, the molar ratio of nickel, cobalt, and manganese in solution B was 4-5:2-2.5:3-3.5; in S4, the concentration of sodium carbonate aqueous solution was 1.8-2.2 mol / L; in S... In step 4, solution B is mixed with an equal volume of sodium carbonate aqueous solution; in step S4, the hydrothermal reaction temperature is 55-65℃ and the time is 11-12h; in step S4, the ratio of the total molar number of nickel, cobalt, manganese, and zirconium to the molar number of lithium in the mixture of precipitate and lithium carbonate is 1:1-1.05; in step S4, the ratio of the total molar number of nickel, cobalt, manganese, and zirconium to the molar number of zirconium is 1:0.001-0.002; in step S4, the primary sintering procedure is: heating to 450-470℃, holding for 4.5-5.5h, then heating to 830-850℃ and holding for 11-13h; in step S4, secondary sintering is performed at 580-620℃ for 2.5-3.5h; in step S4, the weight ratio of intermediate material to ammonium molybdate tetrahydrate is 1:0.01-0.

02.

2. The method for separating positive and negative electrode powders according to claim 1, characterized in that, In S1, the cathode material of the waste ternary lithium battery is lithium nickel cobalt manganese oxide.

3. The method for separating positive and negative electrode powders according to claim 1 or 2, characterized in that, In S1, used ternary lithium batteries are crushed in an inert gas atmosphere.

4. The method for separating positive and negative electrode powders according to claim 1 or 2, characterized in that, In S1, the drying temperature is 80-125℃.

5. The method for separating positive and negative electrode powders according to claim 1 or 2, characterized in that, In S1, waste ternary lithium batteries are crushed while charged to a particle size of 5-8cm.

6. The method for separating positive and negative electrode powders according to claim 1 or 2, characterized in that, In S2, the calcination temperature is 850-1000℃ and the calcination time is 2.5-3.5h.

7. The method for separating positive and negative electrode powders according to claim 1 or 2, characterized in that, In S2, the magnetic induction intensity during magnetic separation is 22000-25000 Gauss.

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