Regeneration and repair method and application of retired ternary lithium battery positive electrode material

Abstract

The invention discloses a method for regenerating and repairing a positive electrode material of a retired ternary lithium battery. The method comprises the following steps: S1, stripping; s2, primary material mixing; s3, primary roasting; s4, crushing; s5, washing the crushed primary sintered material with water, and carrying out filter pressing and drying; s6, performing secondary material mixing; s7, secondary roasting; s8, crushing; s9, washing the crushed secondary sintered material with water, and carrying out filter pressing and drying; and S10, sieving, demagnetizing and packaging: sieving, demagnetizing and packaging the secondary crushed material. The sodium salt and the potassium salt are combined and mixed with the powder removal material for primary roasting, so that fluoride and carbide in the mixture can be removed, the purity of the retired ternary lithium battery positive electrode material is improved, and subsequent lithium supplement repair is facilitated. Impurities are removed through a molten salt method, the original structure of the material is not damaged, and then through lithium supplement repair, surface recrystallization and surface coating modification, the use requirements of the lithium battery are met, and the service life of the lithium battery is prolonged.

Description

Technical Field

[0001] The present invention relates to a method for regenerating and repairing anode materials of retired ternary lithium batteries and application thereof, and in particular to the field of regeneration of waste lithium batteries. Background Art

[0002] As the energy crisis intensifies, the development of metal minerals is limited, new energy vehicles are widely used, and various resources required for power batteries are rapidly consumed, the recycling, repair and reuse of power batteries is an important means to reduce energy consumption. The existing retired battery recycling process is mainly based on hydrometallurgical technology, which has a long process flow, high pollution and high cost. Therefore, it is very important to develop a retired lithium battery recycling method with a short process and low pollution.

[0003] Chinese invention patent CN116470171A discloses a method and system for dry repair and recycling of positive electrode materials for lithium batteries, wherein the powdered material of waste lithium battery pole pieces is mixed with metal oxides, and the mixture is roasted once to replenish lithium, and the mixture is roasted twice. The problem of HF generated by PVDF thermal decomposition during the recycling and repair of lithium batteries is solved, and the problem of battery materials being corroded by HF is greatly reduced. The recycling and repair effects are good, but the carbon impurities in the recycled materials cannot be removed. Chinese invention patent CN114204013B discloses a direct repair method for waste ternary lithium battery positive electrode materials and the ternary positive electrode materials prepared by the method, wherein the active material is ultrasonically placed in distilled water after low-temperature pretreatment, and separated from the aluminum foil current collector to obtain positive electrode powder material; the obtained positive electrode powder material is uniformly mixed with ternary molten salt and co-solvent, and lithium replenishment and impurity removal operations are performed simultaneously at low temperature, and the obtained positive electrode material has good structural recovery and excellent electrochemical properties, but fluoride and carbide are not easy to be removed. Summary of the invention

[0004] In order to develop a method for recycling retired lithium batteries with a short process and low pollution, the first aspect of the present invention provides a method for regenerating and repairing the positive electrode material of retired ternary lithium batteries, comprising the following steps:

[0005] S1 stripping: The positive electrode sheets from the retired ternary lithium battery are carefully disassembled and de-powdered using a stripping machine to obtain de-powdered materials;

[0006] S2 primary mixing: mixing the de-powdered material with the metal salt using a high speed mixer to obtain a mixed material;

[0007] S3 primary calcination: the mixed material is put into a pot, cut into pieces, and calcined to obtain a primary sintered material;

[0008] S4 crushing: crushing the primary sintering material;

[0009] S5: washing the crushed primary sintered material with water, and filtering and drying to obtain a crushed material;

[0010] S6 secondary mixing: mixing the crushed material with lithium salt and additives to obtain a secondary mixed material;

[0011] S7 secondary calcination: the secondary mixed material is put into a pot, cut into pieces, and calcined to obtain a secondary sintered material;

[0012] S8 crushing: crushing the secondary sintering material;

[0013] S9: washing the crushed secondary sintered material with water, and filtering and drying it to obtain a secondary crushed material;

[0014] S10: sieve the secondary crushed material to remove the magnetism and package it.

[0015] As a preferred implementation method, the retired ternary lithium battery positive electrode material is a retired nickel cobalt manganese oxide ternary lithium battery positive electrode material.

[0016] As a preferred implementation method, the molar ratio of the total amount of nickel, cobalt and manganese to the metal salt in the retired nickel-cobalt-manganese oxide ternary lithium battery positive electrode material is 1: (1-1.5).

[0017] As a preferred implementation method, the molar ratio of the total amount of nickel, cobalt and manganese in the retired nickel, cobalt and manganese ternary lithium battery positive electrode material to the metal salt is 1: (1.2-1.5). Preferably, the molar ratio of the total amount of nickel, cobalt and manganese in the retired nickel, cobalt and manganese ternary lithium battery positive electrode material to the metal salt is 1: 1.3.

[0018] As a preferred implementation method, the metal salt includes at least one of a sodium salt and a potassium salt.

[0019] As a preferred implementation method, the primary calcination includes two stages of calcination, low temperature calcination and high temperature calcination. The temperature of the low temperature calcination is 300-500°C, and the temperature of the high temperature calcination is 600-1200°C.

[0020] As a preferred implementation method, the primary calcination includes two stages of calcination, low temperature calcination and high temperature calcination. The temperature of the low temperature calcination is 400°C, and the temperature of the high temperature calcination is 700°C.

[0021] As a preferred implementation method, the atmosphere for the low-temperature calcination is an air atmosphere or an oxygen atmosphere, and the atmosphere for the high-temperature calcination is an oxygen atmosphere.

[0022] As a preferred implementation method, the atmosphere for the low-temperature calcination is an air atmosphere, and the atmosphere for the high-temperature calcination is an oxygen atmosphere.

[0023] As a preferred implementation method, the amount of atmosphere added in the low-temperature roasting in step S2 is 150-200 L / kg of the mixture. Preferably, the amount of atmosphere added in the low-temperature roasting in step S2 is 166.6 L / kg of the mixture.

[0024] As a preferred implementation method, the amount of atmosphere added in the high-temperature roasting in step S2 is 50-100 L / kg of the mixture. Preferably, the amount of atmosphere added in the high-temperature roasting in step S2 is 85 L / kg of the mixture.

[0025] As a preferred implementation method, the low-temperature roasting time is 3-10 hours, and the high-temperature roasting time is 3-10 hours.

[0026] As a preferred implementation method, the low-temperature roasting time is 5-8 hours, and the high-temperature roasting time is 5-8 hours. Preferably, the low-temperature roasting time is 5 hours, and the high-temperature roasting time is 5 hours.

[0027] During the experiment, the inventors found that by using a combination of sodium salt and potassium salt, mixed with the de-powdered material and calcined once, the fluoride and carbide in the mixture can be removed, the purity of the retired ternary lithium battery positive electrode material can be improved, and the subsequent lithium replenishment and repair can be facilitated. Reason: Under low-temperature sintering, PVDF slowly decomposes to produce fluorides such as HF. Fluorine has a strong electronegativity and can react with sodium salt and potassium salt under low-temperature conditions. Sodium salt and potassium salt can effectively adsorb fluoride produced by the decomposition of retired ternary lithium battery positive electrode materials, and prevent fluoride from combining with nickel, cobalt, and manganese to destroy the structure of the material. The combination of sodium salt and potassium salt can, firstly, combine with the carbon in the material under high-temperature reaction to form a soluble carbonate, which can be removed after washing with water; secondly, it can inhibit the carbon thermal reduction reaction on the surface of the material to destroy the surface structure of the material.

[0028] The inventors further discovered that mixing sodium salt and potassium salt and then calcining them, including low-temperature calcination at 300-500°C and high-temperature calcination at 600-1200°C, can achieve the removal of impurities of fluoride and carbide. The reason may be that low-temperature calcination at 300-500°C can promote the adsorption of fluoride by inorganic salts without destroying the structure of the material. High-temperature calcination at 600-1200°C can promote the formation of carbonate between carbon and inorganic salts, avoiding the reduction effect of carbon on the de-powdered material.

[0029] As a preferred implementation method, the total amount of lithium in the crushed material and the lithium salt in step S6 accounts for 7-9wt% of the total mass of the crushed material and the lithium additive.

[0030] As a preferred implementation method, the total amount of lithium in the crushed material and the lithium salt in step S6 accounts for 7-8% of the total mass of the crushed material and the lithium additive.

[0031] As a preferred implementation method, the total amount of lithium in the crushed material and the lithium salt in step S6 accounts for 7.5% of the total mass of the crushed material and the lithium additive.

[0032] As a preferred implementation method, the additive is WO3, the amount of W added in the WO3 is 900-1100 ppm in the overall system, and the amount of W added in the WO3 is 1000 ppm in the overall system.

[0033] As a preferred implementation method, the lithium salt includes at least one of lithium hydroxide, lithium nitrate, lithium chloride, lithium sulfate, lithium acetate, lithium hydroxide, lithium carbonate, lithium borohydride, and lithium bicarbonate.

[0034] As a preferred implementation method, the temperature of the secondary calcination is 500-1000°C, and the time of the secondary calcination is 5-20h.

[0035] As a preferred implementation method, the temperature of the secondary calcination is 600° C., and the time of the secondary calcination is 6 hours.

[0036] As a preferred implementation method, the outer volume of the bowl is 33×33×12 cm.

[0037] As a preferred implementation method, the size of the cut pieces is 6×6×(6-8) cm.

[0038] As a preferred implementation method, the particle size D50 after pulverization in step S4 and step S6 is 5-10 μm, and D100 is less than 25 μm.

[0039] As a preferred implementation method, the screening in step S10 is through a double-layer 325-mesh ultrasonic vibration screen.

[0040] The second aspect of the present invention provides an application of a method for regenerating and repairing retired ternary lithium battery positive electrode materials, which is applied to regenerating lithium battery positive electrode materials.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] (1) The method for regenerating and repairing the positive electrode material of retired ternary lithium batteries described in the present invention uses a combination of sodium salt and potassium salt, which is mixed with the de-powdered material and roasted once, which can remove fluoride and carbide in the mixture, improve the purity of the positive electrode material of retired ternary lithium batteries, and facilitate subsequent lithium replenishment and repair.

[0043] (2) The method for regenerating and repairing the positive electrode material of retired ternary lithium batteries described in the present invention is to mix sodium salt and potassium salt and then roast them. The roasting includes low-temperature roasting at 300-500°C and high-temperature roasting at 600-1200°C, which can remove fluorides and carbides and avoid the negative effects of fluorine and carbon reduction on the de-powdered material.

[0044] (3) The method for regenerating and repairing the positive electrode material of retired ternary lithium batteries described in the present invention replenishes lithium during secondary roasting, controls the lithium content to 7-8wt%, and recrystallizes on the surface of the positive electrode material to achieve surface modification, thereby increasing the capacity of the lithium battery.

[0045] (4) The method for regenerating and repairing the positive electrode material of retired ternary lithium batteries described in the present invention is to replenish lithium by secondary calcination at 600-1000°C for 6-20h, using a solid-phase sintering method, without involving acid-base and other wet processes, and has low environmental pollution and low cost.

[0046] (5) The method for regenerating and repairing the positive electrode material of retired ternary lithium batteries described in the present invention removes impurities through the molten salt method without destroying the original structure of the material, and then repairs it through lithium supplementation, surface recrystallization, and surface coating modification, which meets the use requirements of lithium batteries and extends the service life of lithium batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a SEM photo of Example 1 after step S5;

[0048] Figure 2 This is a SEM photo of Example 1 after step S10;

[0049] Figure 3 This is a test diagram of the cycle effect of the 2032 button battery prepared in Examples 1-3 and Comparative Example 1. DETAILED DESCRIPTION

[0050] Example 1

[0051] A method for regenerating and repairing the positive electrode material of a retired ternary lithium battery comprises the following steps:

[0052] S1 stripping: Use a stripping machine to de-powder the retired ternary lithium battery positive electrode material to obtain de-powdered material;

[0053] S2 primary mixing: mixing the de-powdered material with the metal salt using a high speed mixer to obtain a mixed material;

[0054] S3 primary calcination: the mixed material is put into a pot, cut into pieces, and calcined to obtain a primary sintered material;

[0055] S4 crushing: crushing the primary sintering material;

[0056] S5: washing the crushed primary sintered material with water, and filtering and drying to obtain a crushed material;

[0057] S6 secondary mixing: mixing the crushed material with lithium salt and additives to obtain a secondary mixed material;

[0058] S7 secondary calcination: the secondary mixed material is put into a pot, cut into pieces, and calcined to obtain a secondary sintered material;

[0059] S8 crushing: crushing the secondary sintering material;

[0060] S9: washing the crushed secondary sintered material with water, and filtering and drying it to obtain a secondary crushed material;

[0061] S10: sieve the secondary crushed material to remove the magnetism and package it.

[0062] The retired ternary lithium battery positive electrode material is a retired nickel-cobalt-manganese ternary lithium battery positive electrode material; the molar ratio of the total amount of nickel, cobalt and manganese to the metal salt in the retired nickel-cobalt-manganese ternary lithium battery positive electrode material is 1:1.3.

[0063] The retired ternary lithium battery positive electrode material is CATL's 6 series single crystal scrapped power lithium battery, and the scrapped battery cells are used normally.

[0064] The metal salt is sodium hydroxide.

[0065] The primary calcination includes two stages of calcination, low temperature calcination and high temperature calcination. The temperature of the low temperature calcination is 400°C, and the temperature of the high temperature calcination is 700°C.

[0066] The atmosphere for the low-temperature calcination is an air atmosphere, and the atmosphere for the high-temperature calcination is an oxygen atmosphere.

[0067] The amount of atmosphere added in the step S2 low-temperature roasting is 166.6 L / kg of the mixed material. The amount of atmosphere added in the step S2 high-temperature roasting is 85 L / kg of the mixed material.

[0068] The low-temperature calcination time is 5 hours, and the high-temperature calcination time is 5 hours.

[0069] In the step S6, the total amount of lithium in the crushed material and the lithium additive accounts for 7.5% of the total mass of the crushed material and the lithium additive.

[0070] The lithium salt is lithium hydroxide. The additive is WO3, and the amount of W added in the WO3 is 1000ppm in the overall system.

[0071] The temperature of the secondary calcination is 600° C., and the time of the secondary calcination is 6 hours.

[0072] The volume of the bowl is 33×33×12 cm. The dimensions of the cut pieces are 6×6×7 cm.

[0073] The particle size D50 after pulverization in step S4 and step S6 is 5-10 μm, and D100 is less than 25 μm.

[0074] The screening in step S10 is through a double-layer 325-mesh ultrasonic vibration screen.

[0075] The pulverization is performed by using a jet mill.

[0076] Example 2

[0077] A method for regenerating and repairing retired ternary lithium battery positive electrode materials, the specific implementation method is the same as Example 1, the difference is that the molar ratio of the total amount of nickel, cobalt and manganese to the metal salt in the retired nickel-cobalt-manganese ternary lithium battery positive electrode material is 1:1.2.

[0078] Example 3

[0079] A method for regenerating and repairing retired ternary lithium battery positive electrode materials, the specific implementation method is the same as Example 1, the difference is that the molar ratio of the total amount of nickel, cobalt and manganese to the metal salt in the retired nickel-cobalt-manganese ternary lithium battery positive electrode material is 1:1.5.

[0080] Example 4

[0081] A method for regenerating and repairing the positive electrode material of a retired ternary lithium battery, the specific implementation method is the same as that of Example 1, except that the metal salt is potassium hydroxide.

[0082] Example 5

[0083] A method for regenerating and repairing the positive electrode material of a retired ternary lithium battery, the specific implementation method is the same as that of Example 1, except that the metal salt is sodium chloride.

[0084] Example 6

[0085] A method for regenerating and repairing the positive electrode material of a retired ternary lithium battery, the specific implementation method is the same as that of Example 1, except that the metal salts are potassium chloride and sodium chloride, and the mass ratio is 1:1.

[0086] Example 7

[0087] A method for regenerating and repairing the positive electrode material of a retired ternary lithium battery, the specific implementation method is the same as that of Example 1, except that the metal salt is sodium borohydride.

[0088] Example 8

[0089] A method for regenerating and repairing the positive electrode material of a retired ternary lithium battery, the specific implementation method is the same as Example 1, the difference is that the primary roasting includes two stages of low-temperature roasting and high-temperature roasting, the temperature of the low-temperature roasting is 500°C, and the temperature of the high-temperature roasting is 800°C.

[0090] Example 9

[0091] A method for regenerating and repairing the positive electrode material of a retired ternary lithium battery, the specific implementation method is the same as Example 1, the difference is that the primary roasting includes two stages of low-temperature roasting and high-temperature roasting, the temperature of the low-temperature roasting is 300°C, and the temperature of the high-temperature roasting is 600°C.

[0092] Example 10

[0093] A method for regenerating and repairing the positive electrode material of a retired ternary lithium battery, the specific implementation method is the same as that of Example 1, except that the lithium additive is lithium nitrate.

[0094] Embodiment 11

[0095] A method for regenerating and repairing the positive electrode material of a retired ternary lithium battery, the specific implementation method is the same as that of Example 1, except that the temperature of the secondary calcination is 800°C and the time of the secondary calcination is 5 hours.

[0096] Example 12

[0097] A method for regenerating and repairing the positive electrode material of a retired ternary lithium battery, the specific implementation method is the same as that of Example 1, except that the temperature of the secondary roasting is 1000° C. and the time of the secondary roasting is 3 hours.

[0098] Example 13

[0099] A method for regenerating and repairing the positive electrode material of a retired ternary lithium battery, the specific implementation method is the same as that of Example 1, except that the temperature of the secondary roasting is 600° C. and the time of the secondary roasting is 20 hours.

[0100] Comparative Example 1

[0101] A method for regenerating and repairing the positive electrode material of a retired ternary lithium battery, the specific implementation method is the same as that of Example 1, except that step S6-10 is not included.

[0102] Performance Testing

[0103] The mass ratio of active material: conductive agent: PVDF is 95:2:3, and the compacted density of the pole piece is 3.6g / cm 3 , assembled into a 2032-type button battery. The active material is the repaired material of the embodiment and the comparative example, and the conductive agent is conductive carbon black.

[0104] After assembly, the battery specific capacity performance was tested at 25°C and 4.3-3.0V voltage, with a nominal specific capacity of 170mAh / g and a charge and discharge rate of 0.2C. The battery cycle performance of 100 weeks of 1CC / 1CD test at 25°C and 4.3-3.0V voltage.

[0105] The test results of specific capacity and cycle performance are shown in Table 1, and the cycle effect diagrams of Examples 1-3 and Comparative Example 1 are shown in Figure 3 .

[0106] Table 1

[0107]

[0108]

Claims

1. A method for regenerating and repairing the positive electrode material of retired ternary lithium batteries, characterized in that: The following steps are involved: S1 stripping: The positive electrode sheets from the retired ternary lithium battery are carefully disassembled and de-powdered using a stripping machine to obtain de-powdered materials; S2 primary mixing: mixing the de-powdered material with the metal salt using a high speed mixer to obtain a mixed material; S3 primary calcination: the mixed material is put into a pot, cut into pieces, and calcined to obtain a primary sintered material; S4 crushing: crushing the primary sintering material; S5: washing the crushed primary sintered material with water, and filtering and drying to obtain a crushed material; S6 secondary mixing: mixing the crushed material with lithium salt and additives to obtain a secondary mixed material; S7 secondary calcination: the secondary mixed material is put into a pot, cut into pieces, and calcined to obtain a secondary sintered material; S8 crushing: crushing the secondary sintering material; S9: washing the crushed secondary sintered material with water, and filtering and drying it to obtain a secondary crushed material; S10: sieve the secondary crushed material to remove the magnetism and package it.

2. The method for regenerating and repairing the positive electrode material of retired ternary lithium batteries according to claim 1, characterized in that: The retired ternary lithium battery positive electrode material is a retired nickel cobalt manganese oxide ternary lithium battery positive electrode material.

3. The method for regenerating and repairing the positive electrode material of retired ternary lithium batteries according to claim 2, characterized in that: The molar ratio of the total amount of nickel, cobalt and manganese to the metal salt in the retired nickel-cobalt-manganese oxide ternary lithium battery positive electrode material is 1: (1-1.5).

4. The method for regenerating and repairing the positive electrode material of retired ternary lithium batteries according to claim 1, characterized in that: The primary calcination includes two stages of calcination, low temperature calcination and high temperature calcination. The temperature of the low temperature calcination is 300-500°C, and the temperature of the high temperature calcination is 600-1200°C.

5. The method for regenerating and repairing the positive electrode material of retired ternary lithium batteries according to claim 4, characterized in that: The atmosphere for the low-temperature calcination is an air atmosphere or an oxygen atmosphere, and the atmosphere for the high-temperature calcination is an oxygen atmosphere.

6. The method for regenerating and repairing the positive electrode material of retired ternary lithium batteries according to claim 4, characterized in that: The low-temperature roasting time is 3-10 hours, and the high-temperature roasting time is 3-10 hours.

7. The method for regenerating and repairing the positive electrode material of retired ternary lithium batteries according to claim 1, characterized in that: In step S6, the total amount of lithium in the crushed material and the lithium salt accounts for 7-9wt% of the total mass of the crushed material and the lithium additive.

8. The method for regenerating and repairing the positive electrode material of retired ternary lithium batteries according to claim 1, characterized in that: The temperature of the secondary calcination is 500-1000° C., and the time of the secondary calcination is 5-20 hours.

9. The method for regenerating and repairing the positive electrode material of retired ternary lithium batteries according to claim 1, characterized in that: The particle size D50 after pulverization in step S4 and step S6 is 5-10 μm, and D100 is less than 25 μm.

10. An application of the method for regenerating and repairing the positive electrode material of retired ternary lithium batteries according to any one of claims 1 to 9, characterized in that: Used in recycled lithium battery positive electrode materials.

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