Positive and negative electrode powder separation method

Abstract

The invention discloses a method for separating positive and negative electrode powder. The method comprises the following steps: S1, crushing and drying a waste ternary lithium battery, and winnowing to remove a shell and a diaphragm to obtain a mixture; s2, calcining the mixture in an inert gas atmosphere, and then performing magnetic separation to separate magnetic substances from non-magnetic substances; s3, separating a magnetic substance by wet stripping to separate the positive electrode foil from the positive electrode powder; separating non-magnetic substances by wet stripping, so that the negative electrode foil is separated from the negative electrode powder; s4, dissolving the positive electrode powder in the solution A, adding nickel sulfate, cobalt sulfate and manganese sulfate, uniformly mixing to obtain a solution B, then uniformly mixing the solution B with a sodium carbonate aqueous solution, adjusting the pH value to 8-8.5 by using ammonia water, carrying out a hydrothermal reaction, and collecting a precipitate; uniformly mixing the precipitate with lithium carbonate and zirconium hydroxide, and performing primary sintering to obtain an intermediate material; and uniformly mixing the intermediate material with ammonium molybdate tetrahydrate, and carrying out secondary sintering to obtain the modified positive electrode material.

Description

Technical Field

[0001] The present invention relates to the technical field of battery recycling, and in particular to a method for separating positive and negative electrode powders. Background Art

[0002] Lithium batteries occupy an important position in the field of new energy and its application at home and abroad. They are mainly used in electronic devices such as tablets, smart phones, cameras, and also play an important role in energy storage such as new energy vehicles, power storage, and backup power supply for communication base stations. Compared with traditional materials, ternary cathode materials have higher energy density, better cycle performance, larger specific capacity, longer battery life under the same volume and weight conditions, and higher recycling value and application value.

[0003] At present, the recycling of ternary lithium batteries mainly involves crushing, low-temperature pyrolysis, and high-temperature carbon burning to separate the scrapped batteries, and the final product is a mixed black powder of positive and negative electrodes. The positive and negative electrode materials need to be further separated, which increases the difficulty of subsequent hydrometallurgical extraction of valuable components and increases the emission of pollutants. 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, can effectively separate positive electrode foil, positive electrode powder, negative electrode foil, and negative electrode powder, and has 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 properties.

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

[0006] S1. Crush the waste ternary lithium batteries, dry them, and remove the shells and diaphragms by air separation to obtain a mixed material;

[0007] S2, calcining the mixture in an inert gas atmosphere, and then separating the magnetic substance from the non-magnetic substance by magnetic separation;

[0008] S3, separating the magnetic material by wet stripping, so that the positive electrode foil and the positive electrode powder are separated; separating the non-magnetic material by wet stripping, so that the negative electrode foil and the negative electrode powder are separated;

[0009] S4. Dissolve the positive electrode powder in solution A, add nickel sulfate, cobalt sulfate and manganese sulfate and mix well to obtain solution B, then mix solution B with an aqueous sodium carbonate solution, adjust the pH to 8-8.5 with aqueous ammonia, carry out a hydrothermal reaction, and collect the precipitate; mix the precipitate with lithium carbonate and zirconium hydroxide, and sinter once to obtain an intermediate material; then mix the intermediate material with ammonium molybdate tetrahydrate, and sinter twice to obtain a modified positive electrode 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 S1, the waste ternary lithium batteries are electrically crushed to a particle size of 5-8 cm.

[0014] Preferably, in S2, the calcination temperature is 850-1000°C, 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] The present invention does not require discharge treatment of waste ternary lithium batteries, thereby reducing water pollution; calcination is performed in an inert gas atmosphere, so that the binder and the conductive agent therein are carbonized and work together with graphite to convert the nickel cobalt manganese oxide into magnetic oxides, and then magnetic separation is performed to separate magnetic substances from non-magnetic substances; and then wet stripping is performed to separate the positive electrode foil, positive electrode powder, negative electrode foil, and negative electrode powder, which is simple to operate and greatly improves the recovery rate.

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

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

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

[0020] Preferably, the volume ratio of the aqueous sulfuric acid solution to the aqueous hydrogen peroxide 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, in solution B, the molar ratio of nickel, cobalt and manganese 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 S4, solution B and an aqueous sodium carbonate solution are mixed in equal volumes.

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

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

[0027] Preferably, in 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.

[0028] Preferably, in S4, the primary sintering procedure is: heating to 450-470°C, keeping the temperature for 4.5-5.5h, then heating to 830-850°C, keeping the temperature for 11-13h.

[0029] Preferably, in S4, secondary sintering is performed at 580-620°C for 2.5-3.5h.

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

[0031] In addition, the present invention conducts a hydrothermal reaction on positive electrode powder to form a precipitated precursor of nickel, cobalt and manganese; then sintering with lithium carbonate and zirconium hydroxide to obtain zirconium-doped nickel cobalt manganese oxide lithium, and then mixing and sintering with ammonium molybdate tetrahydrate to coat molybdenum trioxide on its surface; through the cooperation between zirconium doping and molybdenum trioxide coating, on the one hand, the integrity of the internal lattice of the lithium nickel cobalt manganese oxide and the stability of its structure can be maintained, and on the other hand, the conductivity can be improved, the decomposition of the electrolyte can be inhibited, and the insertion and extraction of lithium ions can be promoted, thereby improving its cycle performance and electrochemical performance, and realizing the recycling and reuse of waste ternary positive electrode materials.

[0032] The method of the present invention is simple to operate, has little environmental pollution, can effectively separate positive electrode foil, positive electrode powder, negative electrode foil and negative electrode powder, and has a high recovery rate; the obtained positive electrode powder can be directly repaired and modified to achieve reuse; the modified positive electrode material prepared by the present invention has good cycle performance and electrochemical performance. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is described in detail below through specific embodiments.

[0034] Example 1

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

[0036] S1. Under nitrogen protection, the waste nickel-cobalt-manganese-oxide lithium ternary lithium battery is electrically crushed to a particle size of 5 cm, dried at 80° C., and then the shell and diaphragm are removed by air separation to obtain a mixed material;

[0037] S2, calcining the mixture at 1000°C for 2.5h in a nitrogen atmosphere, and then adjusting the magnetic induction intensity to 25000 gauss, and separating the magnetic substances from the non-magnetic substances with a magnetic separator;

[0038] S3, separating the magnetic material by wet stripping, so that the positive electrode foil and the positive electrode powder are separated; separating the non-magnetic material by wet stripping, so that the negative electrode foil and the negative electrode powder are separated;

[0039] S4. The positive electrode powder was dissolved in solution A (solution A was 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), and nickel sulfate, cobalt sulfate and manganese sulfate were added and mixed to obtain solution B, so that the total concentration of metal ions in solution B was 2 mol / L, and the molar ratio of nickel, cobalt and manganese in solution B was 4:2.5:3.5; then solution B was mixed with 2 mol / L sodium carbonate aqueous solution in equal volumes, the pH was adjusted to 8.5 with ammonia water, and the reaction was hydrothermally reacted at 65°C for 11 hours, and the precipitate was collected. The precipitate is washed with water and dried; the precipitate is then ground and mixed with lithium carbonate and zirconium hydroxide so that the ratio of the total molar number of nickel, cobalt, manganese and zirconium to the molar number of lithium is 1:1.03, and the ratio of the total molar number of nickel, cobalt, manganese and zirconium to the molar number of zirconium is 1:0.002; the temperature is then raised to 470°C and kept warm for 4.5 hours, and then the temperature is raised to 850°C and kept warm for 11 hours for a sintering to obtain an intermediate material; the intermediate material is then ground and mixed with ammonium molybdate tetrahydrate in a weight ratio of 1:0.02, and a secondary sintering is performed at 580°C for 3.5 hours to obtain a modified positive electrode material.

[0040] Example 2

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

[0042] S1. Under nitrogen protection, the waste nickel-cobalt-manganese-oxide lithium ternary lithium battery is electrically crushed to a particle size of 8 cm, dried at 125° C., and then the shell and diaphragm are removed by air separation to obtain a mixture;

[0043] S2, calcining the mixture at 850°C for 3.5h in a nitrogen atmosphere, and then adjusting the magnetic induction intensity to 22000 gauss, and separating the magnetic substances from the non-magnetic substances with a magnetic separator;

[0044] S3, separating the magnetic material by wet stripping, so that the positive electrode foil and the positive electrode powder are separated; separating the non-magnetic material by wet stripping, so that the negative electrode foil and the negative electrode powder are separated;

[0045] S4. The positive electrode powder is dissolved in solution A (solution A is 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), and nickel sulfate, cobalt sulfate and manganese sulfate are added and mixed 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 solution B is mixed with 2 mol / L sodium carbonate aqueous solution in equal volumes, the pH is adjusted to 8 with ammonia water, and the reaction is hydrothermally reacted at 55°C for 12 hours, and the precipitate is collected. , washed with water, and dried; then the precipitate was ground and mixed with lithium carbonate and zirconium hydroxide so that the ratio of the total molar number of nickel, cobalt, manganese and zirconium to the molar number of lithium was 1:1, and the ratio of the total molar number of nickel, cobalt, manganese and zirconium to the molar number of zirconium was 1:0.001, and then the temperature was raised to 450°C, kept warm for 5.5 hours, and then the temperature was raised to 830°C, kept warm for 13 hours for a sintering to obtain an intermediate material; then the intermediate material was ground and mixed with ammonium molybdate tetrahydrate in a weight ratio of 1:0.01, and a secondary sintering was performed at 620°C for 2.5 hours to obtain a modified positive electrode material.

[0046] Example 3

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

[0048] S1. Under nitrogen protection, the waste nickel-cobalt-manganese-oxide lithium ternary lithium battery is charged and crushed to a particle size of 7 cm, dried at 110° C., and then the shell and diaphragm are removed by air separation to obtain a mixed material;

[0049] S2, calcining the mixture at 950° C. for 3 h in a nitrogen atmosphere, and then adjusting the magnetic induction intensity to 23,000 gauss, and separating the magnetic substances from the non-magnetic substances with a magnetic separator;

[0050] S3, separating the magnetic material by wet stripping, so that the positive electrode foil and the positive electrode powder are separated; separating the non-magnetic material by wet stripping, so that the negative electrode foil and the negative electrode powder are separated;

[0051] S4. The positive electrode powder is dissolved in solution A (solution A is a mixture of 1 mol / L sulfuric acid aqueous solution and 30 wt% hydrogen peroxide aqueous solution in a volume ratio of 5:1), and nickel sulfate, cobalt sulfate and manganese sulfate are added and mixed 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 solution B and 2 mol / L sodium carbonate aqueous solution are mixed in equal volumes, the pH is adjusted to 8.5 with ammonia water, and the reaction is hydrothermally reacted at 60°C for 12 hours, and the precipitate is collected. , washed with water, and dried; then the precipitate is 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 be 1:1.05, and the ratio of the total molar number of nickel, cobalt, manganese and zirconium to the molar number of zirconium be 1:0.002, and then the temperature is raised to 460°C, kept warm for 5 hours, and then the temperature is raised to 840°C, kept warm for 12 hours for a sintering to obtain an intermediate material; then the intermediate material is ground and mixed with ammonium molybdate tetrahydrate in a weight ratio of 1:0.01, and a secondary sintering is performed at 600°C for 3 hours to obtain a modified positive electrode material.

[0052] Comparative Example 1

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

[0054] Comparative Example 2

[0055] Take the positive electrode powder obtained in Example 3, do not add zirconium hydroxide, and make the total molar ratio of nickel, cobalt and manganese to the molar ratio of lithium 1:1.05. Otherwise, prepare the modified positive electrode material according to the method in S4 in Example 3.

[0056] Comparative Example 3

[0057] Take the positive electrode powder obtained in Example 3, do not add zirconium hydroxide, and make the total molar ratio of nickel, cobalt and manganese to the molar ratio of lithium 1:1.05. Otherwise, prepare the intermediate material according to the method in S4 in Example 3.

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

[0059] Table 1 Test results

[0060]

[0061]

[0062] It can be seen from Table 1 that the modified positive electrode material prepared by the method of the present invention has good electrochemical performance and cycle performance.

[0063] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for separating positive and negative electrode powders, characterized in that: The steps include: S1. Crushing and drying the waste ternary lithium batteries, removing the shell and the diaphragm by air separation to obtain a mixed material; S2, calcining the mixture in an inert gas atmosphere, and then separating the magnetic substance from the non-magnetic substance by magnetic separation; S3, separating the magnetic material by wet stripping, so that the positive electrode foil and the positive electrode powder are separated; separating the non-magnetic material by wet stripping, so that the negative electrode foil and the negative electrode powder are separated; S4, dissolving the positive electrode powder in solution A, adding nickel sulfate, cobalt sulfate and manganese sulfate to mix well to obtain solution B, then mixing solution B with an aqueous sodium carbonate solution, adjusting the pH to 8-8.5 with aqueous ammonia, performing a hydrothermal reaction, and collecting the precipitate; The precipitate is mixed with lithium carbonate and zirconium hydroxide, and sintered once to obtain an intermediate material; then the intermediate material is mixed with ammonium molybdate tetrahydrate, and sintered twice to obtain a modified positive electrode material.

2. The method for separating positive and negative electrode powders according to claim 1, characterized in that: In S1, the positive electrode material of the waste ternary lithium battery is lithium nickel cobalt manganese oxide; preferably, in S1, the waste ternary lithium battery is crushed in an inert gas atmosphere; preferably, in S1, the drying temperature is 80-125°C; preferably, in S1, the waste ternary lithium battery is charged and crushed to a particle size of 5-8cm.

3. 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°C, and the calcination time is 2.5-3.5h; preferably, in S2, the magnetic induction intensity during magnetic separation is 22000-25000 Gauss.

4. The method for separating positive and negative electrode powders according to any one of claims 1 to 3, characterized in that: In S4, solution A is a mixture of aqueous sulfuric acid solution and aqueous hydrogen peroxide solution; preferably, in solution A, the concentration of sulfuric acid is 0.8-1.2 mol / L; preferably, in solution A, the mass fraction of aqueous hydrogen peroxide solution is 28-30 wt %; preferably, the volume ratio of aqueous sulfuric acid solution to aqueous hydrogen peroxide solution is 4.5-5.5:

1.

5. The method for separating positive and negative electrode powders according to any one of claims 1 to 4, characterized in that: In S4, the total concentration of metal ions in solution B is 1.8-2.2 mol / L; preferably, in S4, in solution B, the molar ratio of nickel, cobalt and manganese is 4-5:2-2.5:3-3.

5.

6. The method for separating positive and negative electrode powders according to any one of claims 1 to 5, characterized in that: In S4, the concentration of the sodium carbonate aqueous solution is 1.8-2.2 mol / L; preferably, in S4, solution B and the sodium carbonate aqueous solution are mixed in equal volumes; preferably, in S4, the temperature of the hydrothermal reaction is 55-65° C., and the time is 11-12 h.

7. The method for separating positive and negative electrode powders according to any one of claims 1 to 6, characterized in that: In S4, in the mixture of precipitate and lithium carbonate, the ratio of the total molar number of nickel, cobalt, manganese and zirconium to the molar number of lithium is 1:1-1.

05.

8. The method for separating positive and negative electrode powders according to any one of claims 1 to 7, characterized in that: In 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.

9. The method for separating positive and negative electrode powders according to any one of claims 1 to 8, characterized in that: In S4, the primary sintering procedure is: heating to 450-470°C, keeping warm for 4.5-5.5h, then heating to 830-850°C, keeping warm for 11-13h.

10. The method for separating positive and negative electrode powders according to any one of claims 1 to 9, characterized in that: In S4, secondary sintering is performed at 580-620°C for 2.5-3.5h; preferably, in S4, the weight ratio of the intermediate material to ammonium molybdate tetrahydrate is 1:0.01-0.02.

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