Method for directly repairing and regenerating ternary positive electrode recycled material and application of ternary positive electrode recycled material

Abstract

The invention discloses a method for directly repairing and regenerating a ternary positive electrode recycled material. The method comprises the following steps: S1, disassembling a ternary retired battery; s2, sintering to remove impurities; s3, removing powder and sieving; s4, mixing with crystalline lithium salt; s5, crushing and sieving after sintering and cooling; s6, mixing with a metal oxide; and S7, sintering, cooling, removing iron, and sieving. The eutectic lithium salt is used as a lithium source for lithium supplement, so that the diffusion rate of lithium ions can be increased, the concentration of the lithium ions can be improved, the reaction temperature of lithium supplement recovery can be reduced, and the energy consumption can be reduced. The ternary lithium battery is wrapped by the metal oxide, residual lithium on the surface of the material can be utilized, a layer of fast ion conductor can be formed on the surface of the material in situ, and the residual lithium on the washed surface is removed, so that the process is shortened, the cost is reduced, the transmission rate of lithium ions can be further improved, and the rate capability of the battery is improved. And the fast ion conductor structure can isolate the contact between the electrolyte and the positive electrode material, so that side reaction is reduced, and the cycle performance is improved.

Description

Technical Field

[0001] The present invention relates to the field of batteries and preparation methods, and in particular to a direct repair and regeneration method for ternary positive electrode recycling materials and applications thereof. Background Art

[0002] Lithium batteries contain high-value metal substances such as lithium, nickel, cobalt, and manganese. Recycling, repairing, and reusing lithium batteries is of great significance to the environment, economy, and resources. Existing methods for recycling lithium batteries include pyrometallurgical recycling, hydrometallurgy, etc. Pyrometallurgical recycling uses high-temperature heating methods, and impurity components overflow with furnace gas or remain in the slag. Lithium ions are recovered in the form of lithium carbonate, but most of the recovered metals exist in the form of alloys, which are difficult to separate, and have high energy consumption, produce toxic substances, and the recovery rate of lithium ions is not high. Wet recycling is to use different leaching agents to leach waste positive electrode materials under different conditions. During the leaching process, iron, lithium, nickel, cobalt, manganese, etc. enter the acid leaching solution together with impurity elements. The purification process is relatively complicated, and a large amount of acid and alkaline wastewater will be produced, which needs to be treated, and the environmental pressure is high. Therefore, it is very important to develop a positive electrode material repair and regeneration method with high recovery efficiency, low energy consumption, and low environmental pressure.

[0003] Chinese invention patent CN113488713A discloses a method for recycling ternary materials for power batteries. The positive electrode material forms a slurry, and then co-precipitates with an oxalate solution to form a precursor, and then sintered with lithium for repair and regeneration. No phosphorus-containing solution is added during the operation, and the pollution to the environment is relatively small, but liquid leaching is required, and a large amount of wastewater needs to be treated, which puts great pressure on environmental protection. Chinese invention patent CN118054112A discloses a method for regenerating and repairing highly failed ternary battery positive electrode materials with low-temperature molten salts. The positive electrode material is mixed and ground with the eutectic salt LiBr-LiOH. The low-melting-point eutectic salt LiOH-LiBr provides a lithium-rich molten environment to solve the lithium loss and structural defects in the highly failed ternary battery positive electrode materials. However, after lithium supplementation, ultrasonic washing with deionized water is required to reduce the residual lithium on the surface, resulting in lithium loss, and at the same time, it is inevitable to cause damage to the material structure and increase the material powder resistance. Drying is required after washing, and the process is complicated and energy consumption is high. Summary of the invention

[0004] In order to develop a positive electrode material repair and regeneration method with high recovery efficiency, low energy consumption and low environmental pressure, the first aspect of the present invention provides a ternary positive electrode recovery material direct repair and regeneration method, comprising the following steps:

[0005] S1 dismantles the retired ternary battery to obtain the ternary positive electrode sheet;

[0006] S2 sintering the ternary positive electrode sheet to remove fluoropolymer impurities to obtain ternary positive electrode recycling materials;

[0007] S3 de-powders the ternary cathode recycling materials, sieves them, and obtains ternary cathode powder;

[0008] S4 mixes the ternary positive electrode powder and the crystalline lithium salt at a high speed to obtain a ternary positive electrode mixed powder;

[0009] S5: sintering the ternary positive electrode mixed powder, and crushing and sieving it after cooling to obtain the lithium-supplemented and repaired ternary positive electrode powder;

[0010] S6 mixes the lithium-repaired ternary cathode powder with metal oxide at high speed;

[0011] S7 sintering the mixture after step S6, removing iron after cooling, and sieving to obtain a regenerated ternary positive electrode material.

[0012] As a preferred embodiment, the retired ternary battery is a nickel-cobalt-manganese ternary lithium battery.

[0013] As a preferred embodiment, the crystalline lithium salt includes at least two of LiOH, LiNO3, Li2O, LiF, CH3COOLi, LiI, and LiCO3.

[0014] As a preferred embodiment, the crystalline lithium salt comprises a combination of LiNO3 and Li2O; as a preferred embodiment, the crystalline lithium salt comprises a combination of LiNO3 and LiF.

[0015] As a preferred embodiment, the mass ratio of LiNO3 to Li2O is (0.6-0.8): (0.4-0.2); the mass ratio of LiNO3 to LiF is (0.6-0.8): (0.4-0.2). Preferably, the mass ratio of LiNO3 to Li2O is 0.8:0.2; the mass ratio of LiNO3 to LiF is 0.8:0.2.

[0016] As a preferred embodiment, the sintering temperature in step S2 is 350-550° C., the heating rate is 1-4° C. / min, and the heat preservation reaction is 2-6 hours.

[0017] As a preferred embodiment, the sintering temperature in step S2 is 350-450° C., the heating rate is 1-3° C. / min, and the heat preservation reaction is 4-6 hours.

[0018] As a preferred implementation, the sintering temperature in step S2 is 400° C., the heating rate is 2° C. / min, and the heat preservation reaction is performed for 5 hours.

[0019] As a preferred embodiment, the step S3 includes: firstly using a pneumatic stripping machine to remove powder, and performing a primary screening to remove large particles of foreign matter; and then air flow crushing and performing a secondary screening.

[0020] As a preferred embodiment, the particle size of the material under the sieve after the first sieving is ≤50 mesh, the particle size of the material under the sieve after the second sieving is ≤325 mesh, and the D50 particle size of the ternary positive electrode powder is 3.2-4.5 μm.

[0021] As a preferred embodiment, the D50 particle size of the ternary positive electrode powder is 3.5-4 μm. Preferably, the D50 particle size of the ternary positive electrode powder is 3.78 μm.

[0022] As a preferred embodiment, after step S3, an element analyzer is used to test the initial lithium content in the ternary positive electrode powder, the total lithium content in the ternary positive electrode mixed powder is 7-8wt%, and the amount of crystalline lithium salt added is the difference between the total lithium content and the initial lithium content.

[0023] As a preferred embodiment, the total lithium content in the ternary positive electrode mixed powder is 7.5wt%.

[0024] During the experiment, the inventors found that using eutectic lithium salt as a lithium source for lithium replenishment can increase the diffusion rate of lithium ions, improve the concentration of lithium ions, and reduce the reaction temperature of lithium recovery and replenishment. The possible reason is that when two eutectic lithium salts are used as lithium sources for lithium replenishment, the two lithium sources work together to have a higher concentration of lithium ions and have a mutually promoting effect, which can increase the diffusion of lithium ions in the plastic. In addition, the melting point of the two lithium salts working together is lower than that of a single lithium source, which can reduce the sintering temperature in the lithium replenishment reaction and reduce energy consumption.

[0025] As a preferred embodiment, the sintering temperature in step S5 is 600-900° C., the heating rate is 1-4° C. / min, the heat preservation reaction is 8-15 hours, and the sintering atmosphere is oxygen.

[0026] As a preferred embodiment, the sintering temperature in step S5 is 800-850° C., the heating rate is 1-3° C. / min, the heat preservation reaction is 10-13 hours, and the sintering atmosphere is oxygen.

[0027] As a preferred embodiment, the sintering temperature in step S5 is 820° C., the heating rate is 2° C. / min, the heat preservation reaction is 12 hours, and the sintering atmosphere is oxygen.

[0028] As a preferred embodiment, the added amount of the metal oxide is 0.2-0.6wt% of the mass of the lithium-repaired ternary positive electrode powder.

[0029] As a preferred embodiment, the added amount of the metal oxide is 0.3-0.5wt% of the mass of the lithium-repaired ternary positive electrode powder.

[0030] As a preferred embodiment, the added amount of the metal oxide is 0.4wt% of the mass of the lithium-supplemented ternary positive electrode powder.

[0031] As a preferred embodiment, the metal oxides include but are not limited to at least two of zirconium oxide, aluminum oxide, titanium oxide, tungsten oxide, cobalt oxide, niobium oxide, and cerium oxide.

[0032] As a preferred embodiment, the metal oxide is a combination of zirconium oxide and titanium oxide. Preferably, the mass ratio of zirconium oxide to titanium oxide is 1:(1-3).

[0033] As a preferred implementation, the mass ratio of zirconium oxide to titanium oxide is 1:1.

[0034] The inventors further discovered that wrapping ternary lithium batteries with metal oxides can further increase the transmission rate of lithium ions, improve rate performance, reduce side reactions, and improve cycle performance. The possible reason is speculated to be: wrapping ternary lithium battery materials with metal oxides can utilize the residual lithium on the surface of the material to form a layer of fast ion conductor in situ on the surface of the material, which can eliminate the step of washing the residual lithium on the surface, shorten the process, and reduce costs. In addition, the in-situ generated fast ion conductor structure can provide a channel for rapid migration of lithium ions, increase the transmission speed of lithium ions, and improve rate performance. The formed fast ion conductor structure will also isolate the contact between the electrolyte and the positive electrode material, reduce side reactions, and improve cycle performance.

[0035] As a preferred implementation, the sintering temperature in step S7 is 400-800° C., the heating rate is 1-4° C. / min, and the heat preservation reaction is 6-10 hours.

[0036] As a preferred embodiment, the sintering temperature in step S7 is 650-750° C., the heating rate is 1-3° C. / min, and the heat preservation reaction is 7-9 hours.

[0037] As a preferred implementation, the sintering temperature in step S7 is 700° C., the heating rate is 2° C. / min, and the heat preservation reaction is performed for 8 hours.

[0038] The second aspect of the present invention provides an application of a method for directly repairing and regenerating ternary positive electrode recycling materials, which is applied to the repair and regeneration of ternary lithium batteries.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] (1) The direct repair and regeneration method for ternary positive electrode recycling materials described in the present invention uses eutectic lithium salt as a lithium source for lithium replenishment, which can increase the diffusion rate of lithium ions, improve the concentration of lithium ions, reduce the reaction temperature of lithium recovery and replenishment, and reduce energy consumption.

[0041] (2) The direct repair and regeneration method of the ternary positive electrode recycling material described in the present invention uses metal oxides to wrap the ternary lithium battery, which can further increase the transmission rate of lithium ions and enhance the battery's rate performance.

[0042] (3) The direct repair and regeneration method of the ternary positive electrode recycling material described in the present invention uses metal oxides to wrap the ternary lithium battery, which can utilize the residual lithium on the surface of the material to form a layer of fast ion conductor in situ on the surface of the material, thereby eliminating the step of washing the residual lithium on the surface with water, shortening the process and reducing costs.

[0043] (4) In the direct repair and regeneration method of the ternary positive electrode recycling material described in the present invention, the fast ion conductor structure formed by the metal oxide wrapping the ternary lithium battery will isolate the contact between the electrolyte and the positive electrode material, reduce side reactions, and improve the cycle performance.

[0044] (5) The direct repair and regeneration method of the ternary positive electrode recycling material described in the present invention has a short process, simple operation, and is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a physical picture of the ternary square aluminum shell recycled battery;

[0046] Figure 2 The ternary positive electrode sheet after disassembling the retired ternary battery;

[0047] Figure 3 This is the SEM image of the ternary positive electrode powder before repair in step S3;

[0048] Figure 4 This is a SEM image of the ternary positive electrode powder after repair in step S7;

[0049] Figure 5 The rate curves of batteries prepared with the ternary positive electrode powders of Example 1 and Comparative Example 1 are shown;

[0050] Figure 6 The cycle curve diagram of the battery prepared by using the ternary positive electrode powder of Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0051] Example 1

[0052] A method for directly repairing and regenerating ternary positive electrode recycling materials, comprising the following steps:

[0053] S1 discharges the retired ternary battery using a discharge test cabinet, removes the battery after the discharge is completed, and disassembles and separates it under safe conditions to obtain the ternary positive electrode sheet;

[0054] S2 sintering the ternary positive electrode sheet to remove fluoropolymer impurities to obtain ternary positive electrode recycling materials;

[0055] S3 de-powders the ternary cathode recycling materials, sieves them, and obtains ternary cathode powder;

[0056] S4 mixes the ternary positive electrode powder and the crystalline lithium salt at a high speed to obtain a ternary positive electrode mixed powder;

[0057] S5: sintering the ternary positive electrode mixed powder, and crushing and sieving it after cooling to obtain the lithium-supplemented and repaired ternary positive electrode powder;

[0058] S6 mixes the lithium-repaired ternary cathode powder with metal oxide at high speed;

[0059] S7 sintering the mixture after step S6, removing iron after cooling, and sieving to obtain a regenerated ternary positive electrode material.

[0060] The retired ternary battery is a nickel-cobalt-manganese ternary lithium battery of model 622;

[0061] The sintering temperature in step S2 is 400° C., the heating rate is 2° C. / min, and the reaction is kept warm for 5 hours.

[0062] The step S3 includes: firstly using a pneumatic stripping machine to remove powder, and then screening once to remove large particles of foreign matter; and then air flow crushing and screening twice.

[0063] The particle size of the material under the sieve after the first sieving is ≤50 mesh, the particle size of the material under the sieve after the second sieving is ≤325 mesh, and the D50 particle size of the ternary positive electrode powder is 3.78 μm.

[0064] After step S3, the initial lithium content in the ternary positive electrode powder was tested by an element analyzer and was 6.3wt%.

[0065] The crystalline lithium salt is a combination of LiNO3 and Li2O, and the weight ratio of LiNO3 to Li2O is 0.8:0.2. The total lithium content in the ternary positive electrode mixed powder is 7.5wt%, and the added amount of the crystalline lithium salt is 1.2wt%.

[0066] The sintering temperature in step S5 is 820° C., the heating rate is 2° C. / min, the heat preservation reaction is 12 hours, and the sintering atmosphere is oxygen.

[0067] The added amount of the metal oxide is 0.4wt% of the mass of the lithium-supplemented ternary positive electrode powder.

[0068] The metal oxide is a combination of zirconium oxide and titanium oxide, with a mass ratio of 1:1.

[0069] The sintering temperature in step S7 is 700° C., the heating rate is 2° C. / min, and the reaction is kept warm for 8 hours.

[0070] Example 2

[0071] A method for direct repair and regeneration of ternary positive electrode recycling materials, the specific implementation method is the same as Example 1, the difference is that the crystalline lithium salt is a combination of LiNO3 and LiF, and the weight ratio is 0.8:0.2.

[0072] Example 3

[0073] A method for directly repairing and regenerating ternary positive electrode recycling materials, the specific implementation method is the same as Example 1, the difference is that the metal oxide is a combination of zirconium oxide and tungsten oxide, and the mass ratio is 1:1.

[0074] Example 4

[0075] A method for directly repairing and regenerating ternary positive electrode recycling materials, the specific implementation method is the same as Example 1, the difference is that the metal oxide is a combination of zirconium oxide and aluminum oxide, and the mass ratio is 1:1.

[0076] Comparative Example 1

[0077] A method for directly repairing and regenerating ternary positive electrode recycling materials, comprising the following steps:

[0078] S1 discharges the retired ternary battery using a discharge test cabinet, removes the battery after the discharge is completed, and disassembles and separates it under safe conditions to obtain the ternary positive electrode sheet;

[0079] S2 sintering the ternary positive electrode sheet to remove fluoropolymer impurities to obtain ternary positive electrode recycling materials;

[0080] S3 de-powders the ternary positive electrode recycling materials, sieves them, and obtains ternary positive electrode powder.

[0081] The retired ternary battery is a nickel-cobalt-manganese ternary lithium battery of model 622;

[0082] The sintering temperature in step S2 is 450° C., the heating rate is 2° C. / min, and the reaction is kept warm for 5 hours.

[0083] The step S3 includes two steps of screening, specifically: firstly, a pneumatic stripping machine is used to remove powder and screen once to remove large particles of foreign matter; then, air flow crushing is performed and a second screening is performed.

[0084] The particle size of the material under the sieve after the first sieving is ≤50 mesh, the particle size of the material under the sieve after the second sieving is ≤325 mesh, and the D50 particle size of the ternary positive electrode powder is 3.78 μm.

[0085] After step S3, the lithium content in the ternary positive electrode powder was tested using an element analyzer and was recorded as 6.3 wt%.

[0086] Comparative Example 2

[0087] A method for directly repairing and regenerating ternary positive electrode recycling materials, comprising the following steps:

[0088] S1 discharges the retired ternary battery using a discharge test cabinet, removes the battery after the discharge is completed, and disassembles and separates it under safe conditions to obtain the ternary positive electrode sheet;

[0089] S2 sintering the ternary positive electrode sheet to remove fluoropolymer impurities to obtain ternary positive electrode recycling materials;

[0090] S3 de-powders the ternary positive electrode recovery material, sieves it, and obtains ternary positive electrode powder;

[0091] S4 mixes the ternary positive electrode powder and the crystalline lithium salt at a high speed to obtain a ternary positive electrode mixed powder;

[0092] S5 sintering the ternary positive electrode mixed powder, and crushing and sieving it after cooling to obtain the lithium-supplemented and repaired ternary positive electrode powder.

[0093] The retired ternary battery is a nickel-cobalt-manganese ternary lithium battery of model 622;

[0094] The sintering temperature in step S2 is 400° C., the heating rate is 2° C. / min, and the reaction is kept warm for 5 hours.

[0095] The step S3 includes two steps of screening, specifically: firstly, a pneumatic stripping machine is used to remove powder and screen once to remove large particles of foreign matter; then, air flow crushing is performed and a second screening is performed.

[0096] The particle size of the material under the sieve after the first sieving is ≤50 mesh, the particle size of the material under the sieve after the second sieving is ≤325 mesh, and the D50 particle size of the ternary positive electrode powder is 3.78 μm.

[0097] After step S3, the lithium content in the ternary positive electrode powder was tested by an element analyzer and recorded as 6.3wt%.

[0098] The crystalline lithium salt is a combination of LiNO3 and Li2O, and the weight ratio of LiNO3 to Li2O is 0.8:0.2. The total lithium content in the ternary positive electrode mixed powder is 7.5wt%, and the added amount of the crystalline lithium salt is 1.2wt%.

[0099] The sintering temperature in step S5 is 820° C., the heating rate is 2° C. / min, the heat preservation reaction is 12 hours, and the sintering atmosphere is oxygen.

[0100] Performance Testing

[0101] 1. Use a Phenom desktop scanning electron microscope to take SEM images of the samples. The electron microscope images of Example 1 and Comparative Example 1 are shown in Figure 3 and Figure 4 .

[0102] 2. Potentiometric titration analyzer is used to test the residual lithium on the surface.

[0103] 3. pH tester to measure pH value.

[0104] 4. Capacity test: The products of the embodiment and the comparative example were prepared into 2032-type button batteries and the first capacity test was carried out using a blue power test cabinet at 0.2CC / 0.2CD, with a charge and discharge cut-off voltage of 3.0-4.3V.

[0105] 5. Rate test: The products of the embodiment and the comparative example were prepared into 2032 button batteries and discharged at different rates (0.2C / 0.5C / 1C / 2C0.2C) using a blue power test cabinet under 0.2C charging conditions, wherein the charge and discharge cut-off voltage was 3.0-4.3V; the rate test diagram of embodiment 1 and comparative example 1 is shown in Figure 5 A: Example 1; B: Comparative Example 1.

[0106] 6. Cycle performance test: The products of the embodiment and comparative example were prepared into 2032 button batteries and subjected to 1CC / 1CD cycle performance test using a blue power test cabinet, wherein the charge and discharge cut-off voltage was 3.0-4.3V. The cycle test diagram of embodiment 1 and comparative example 1 is shown in Figure 6 A: Example 1; B: Comparative Example 1.

[0107] The test results are shown in Table 1.

[0108] Table 1

[0109]

[0110] It can be seen from Table 1 that the capacity and first efficiency of the repaired samples are greatly improved compared with those of Comparative Example 1, and the lithiation and charge-withdrawal performance of the repaired and regenerated samples are significantly improved. Moreover, after coating with metal oxides, the residual alkali on the surface of the repaired samples is reduced, and the first efficiency is improved, indicating that after coating, the metal oxide reacts with the residual Li on the surface to consume excess lithium and generate a fast ion conductor in situ, which reduces the residual alkali on the surface and accelerates the transmission rate of lithium ions. Among them, the comprehensive performance of the positive electrode material obtained by the repair and regeneration scheme mentioned in Example 1 is the most excellent.

Claims

1. A method for direct repair and regeneration of ternary positive electrode recycling materials, characterized in that: The following steps are involved: S1 dismantles the retired ternary battery to obtain the ternary positive electrode sheet; S2 sintering the ternary positive electrode sheet to remove fluoropolymer impurities to obtain ternary positive electrode recycling materials; S3 de-powders the ternary cathode recycling materials, sieves them, and obtains ternary cathode powder; S4 mixes the ternary positive electrode powder and the crystalline lithium salt at a high speed to obtain a ternary positive electrode mixed powder; S5: sintering the ternary positive electrode mixed powder, and crushing and sieving it after cooling to obtain the lithium-supplemented and repaired ternary positive electrode powder; S6 mixes the lithium-repaired ternary cathode powder with metal oxide at high speed; S7 sintering the mixture after step S6, removing iron after cooling, and sieving to obtain a regenerated ternary positive electrode material.

2. The direct repair and regeneration method of ternary positive electrode recycling materials according to claim 1 is characterized in that: The crystalline lithium salt includes at least two of LiOH, LiNO3, Li2O, LiF, CH3COOLi, LiI, and LiCO3.

3. The direct repair and regeneration method of ternary cathode recycling materials according to claim 1 is characterized in that: The sintering temperature in step S2 is 350-550° C., the heating rate is 1-4° C. / min, and the heat preservation reaction is performed for 2-6 hours.

4. The direct repair and regeneration method of ternary cathode recycling materials according to claim 1, characterized in that: The step S3 includes: firstly using a pneumatic stripping machine to remove powder and perform a primary screening; and then air flow crushing and performing a secondary screening.

5. The direct repair and regeneration method of ternary cathode recycling materials according to claim 4 is characterized in that: The particle size of the material under the sieve after the first sieving is ≤50 mesh, the particle size of the material under the sieve after the second sieving is ≤325 mesh, and the D50 particle size of the ternary positive electrode powder is 3.2-4.5 μm.

6. The direct repair and regeneration method of ternary cathode recycling materials according to claim 1, characterized in that: After step S3, an element analyzer is used to test the initial lithium content in the ternary positive electrode powder. The total lithium content in the ternary positive electrode mixed powder is 7-8wt%, and the amount of crystalline lithium salt added is the difference between the total lithium content and the initial lithium content.

7. The direct repair and regeneration method of ternary cathode recycling materials according to claim 1, characterized in that: The sintering temperature in step S5 is 600-900° C., the heating rate is 1-4° C. / min, the heat preservation reaction is 8-15 hours, and the sintering atmosphere is oxygen.

8. The direct repair and regeneration method of ternary cathode recycling materials according to claim 1, characterized in that: The added amount of the metal oxide is 0.2-0.6wt% of the mass of the lithium-supplemented and repaired ternary positive electrode powder.

9. The direct repair and regeneration method of ternary cathode recycling materials according to claim 1, characterized in that: The sintering temperature in step S7 is 400-800° C., the heating rate is 1-4° C. / min, and the heat preservation reaction is 6-10 hours.

10. An application of the direct repair and regeneration method of ternary positive electrode recycling materials according to any one of claims 1 to 9, characterized in that: Used in the repair and regeneration of ternary lithium batteries.

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