A rapid repair method for ternary lithium materials

Abstract

The application discloses a kind of quick repair methods of ternary lithium material, it is related to battery material repair field.The method includes that ternary pole piece is broken, screening is mixed with white carbon black, carries out primary roasting in inert gas atmosphere, removes white carbon black by separation, removes suspended substance by washing with water, after material drying, ball milling, carries out secondary roasting in inert gas atmosphere, obtains repaired ternary lithium pole piece powder.The application carries out repair processing to the pole piece of electric performance drop, adds white carbon black in the process of roasting and removing organic matter, utilizes white carbon black and the reaction of HF generated by pyrolysis, avoids the reaction of HF and ternary lithium crystal, guarantees the integrity of ternary crystal structure, significantly improves the electric performance repair effect of pole piece powder, after being applied to the preparation battery, capacity, charging efficiency and electric cycle stability are significantly improved, avoid the ecological pollution caused by irregular discharge of waste ternary lithium material to environment, with economy and sustainable development.

Description

Technical Field

[0001] This invention relates to the field of battery material repair, and more particularly to a rapid repair method for ternary lithium materials. Background Technology

[0002] Lithium-ion batteries, as a new type of energy storage device, have received increasing attention due to their advantages such as high energy density, high voltage, good cycle performance, low self-discharge, long storage time, safe operation, and low price. With the increasing maturity of related technologies, they have achieved industrial application in multiple fields. However, lithium-ion batteries contain large amounts of heavy metals such as lithium, nickel, cobalt, and manganese, as well as organic electrolytes. Improper handling can cause serious damage to the ecological environment and human health, and also result in enormous resource waste. Domestic reserves of related mineral resources are limited, and the industry has a high dependence on imported raw materials. For example, my country imports 80%–90% of its cobalt resources from the Democratic Republic of Congo, with an import dependence rate consistently exceeding 95%. It is projected that by 2025, my country's dependence on imported lithium and nickel will still remain above 70%.

[0003] After multiple charge-discharge cycles, the loss of lithium in the active material of lithium-ion batteries directly leads to capacity decay. Generally, new energy vehicle power batteries with a capacity below 80% can no longer be used in vehicles but can be reused. When the battery capacity drops below 50%, it can no longer be used, but the positive electrode material contains large amounts of lithium, nickel, cobalt, and manganese. Therefore, the recycling of retired lithium-ion battery positive electrode materials is of great significance for addressing ecological and environmental risks, ensuring resource supply security, and promoting the green and sustainable development of the lithium battery industry. Summary of the Invention

[0004] This invention provides a rapid repair method for ternary lithium materials, which can efficiently repair the electrical properties of ternary lithium electrode powder, avoid the influence of HF generated during pyrolysis on the ternary lithium crystal structure, and improve repair efficiency.

[0005] To address the aforementioned technical problems, this invention aims to provide a rapid repair method for ternary lithium materials, comprising the following steps:

[0006] (1) The ternary electrode sheet is crushed and sieved to obtain the pre-repair electrode sheet powder;

[0007] (2) Mix the pre-repair electrode powder with silica evenly and calcine it once in an inert gas atmosphere. The calcine temperature is 400-550℃.

[0008] (3) The cooled mixture is separated by a cyclone separator to obtain silica with a lower specific gravity and ternary lithium electrode powder with a higher specific gravity;

[0009] (4) Stir and mix the material with a larger specific gravity with water, remove the suspended substances after standing;

[0010] (5) Dry and ball mill the settled material after filtering water, to obtain the pretreated ternary lithium electrode sheet powder;

[0011] (6) Perform secondary calcination on the pretreated ternary lithium electrode sheet powder in an inert gas atmosphere, the secondary calcination temperature is 600-800℃, to obtain the repaired ternary lithium electrode sheet powder.

[0012] By adopting the above scheme, the electrode sheet after multiple cycles is repaired and treated, in the process of calcination to remove organic matter, PVDF in the electrode sheet powder will pyrolyze to produce HF, and HF has strong oxidizing property, which will cause the collapse of the ternary lithium crystal structure, and in the process of primary calcination, the addition of white carbon black utilizes the reaction between silicon dioxide in the white carbon black and HF to generate gaseous SiF and discharge it, avoiding the reaction between HF and ternary lithium crystals, and ensuring the integrity of the ternary crystal structure, and after subsequent secondary calcination repair, the electrical performance repair effect of the electrode sheet powder can be significantly improved, and the surface of the repaired electrode sheet powder is smooth, and the capacity, charging efficiency and electrical cycle stability after being applied to prepare a battery are significantly improved.

[0013] As a preferred scheme, in step (2), the addition amount of white carbon black is 1%-10% of the mass fraction of the electrode sheet powder before repair.

[0014] As a preferred scheme, in step (1), the screening uses a standard sieve of 150-500 meshes.

[0015] As a preferred scheme, in step (1), the ternary electrode sheet is one of 111, 523 or 622 ternary electrode sheets.

[0016] As a preferred scheme, in step (2), the heating rate in the process of primary calcination is 5-10℃ / min, and the holding time is 1.5-4h.

[0017] As a preferred scheme, in step (6), the heating rate in the process of secondary calcination is 5-10℃ / min, and the holding time is 30-210min.

[0018] As a preferred scheme, in steps (2) and (6), the inert gas is nitrogen.

[0019] As a preferred scheme, in step (4), the material with a larger specific gravity is added with water in a solid-liquid volume ratio of 1:(3-5), the stirring time is 30-60min, and the standing time is 10-20min.

[0020] By adopting the above scheme, the carbon-containing substances and inorganic salts and other conductive impurities in the electrode sheet powder are cleaned and removed, avoiding affecting the electrical performance of the electrode sheet powder.

[0021] As a preferred embodiment, in step (5), the drying temperature is 40-100℃ and the drying time is 12-36h.

[0022] As a preferred embodiment, in step (5), the ball milling rate is 200-500 rpm / min and the ball milling time is 30-210 min.

[0023] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0024] 1. This application addresses the repair of electrode sheets whose electrical performance has deteriorated due to repeated use. During the calcination process to remove organic matter, silica is added. The silica in the silica reacts with HF generated by pyrolysis to produce gaseous SiF, which is then released. This avoids the reaction between HF and ternary lithium crystals, ensuring the integrity of the ternary crystal structure. After subsequent secondary calcination repair, the electrical performance of the electrode powder can be significantly improved. The surface of the repaired electrode powder is smooth and flat, and its capacity, charging efficiency, and electrical cycle stability are significantly improved when applied to battery manufacturing.

[0025] 2. Since discarded ternary lithium materials contain a large amount of heavy metals, irregular emissions will cause ecological pollution and environmental damage. This application improves the recycling method of ternary lithium materials, which has obvious advantages such as economy and sustainable development. Attached Figure Description

[0026] Figure 1 This is a flowchart illustrating a rapid repair method for ternary lithium materials according to an embodiment of the present invention.

[0027] Figure 2 : This is a SEM image of the pre-electrode powder in step (1) of embodiment 2 of the present invention;

[0028] Figure 3 : SEM image of the repaired ternary lithium electrode powder obtained in step (6) of Example 2 of the benzene invention. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1

[0031] A rapid repair method for ternary lithium materials, such as Figure 1As shown, it includes the following steps:

[0032] (1) The scrapped 523 ternary electrode sheets are placed in the crushing equipment for crushing, and then screened through a 200-mesh standard sieve. The black powder that passes through the sieve is the electrode sheet powder before repair.

[0033] (2) Add 1% by mass of silica to the pre-repair electrode powder. The silica particle size is 20nm. Then mix it evenly with a high-speed mixer, place it in a muffle furnace, purge with nitrogen for 2 hours, start heating, heat to 450℃ at a heating rate of 5℃ / min, keep it at the temperature for 2 hours, and then cool it naturally to room temperature.

[0034] (3) The mixture is passed through a cyclone separator with a parameter of 6 Hz. The cyclone separator separates the material with a smaller specific gravity and the material with a larger specific gravity. The material with a smaller specific gravity is silica, and the material with a larger specific gravity is ternary lithium electrode powder.

[0035] (4) Place the material with a higher specific gravity in a beaker, add pure water at a solid-liquid ratio of 1:3, stir the mixture for 40 minutes to allow the material to be fully sheared, let it stand for 20 minutes and the carbon-containing substances in the material will be floated out by the buoyancy of the water, and the remaining material will naturally sink to the bottom of the liquid.

[0036] (5) Remove the suspended matter on the settled material, and wash the material multiple times according to step (4) to remove C, white carbon black and inorganic salts. After filtering the water, place the settled material in an oven, adjust the temperature to 60℃ and dry it with a forced air for 24 hours. Then place it on a ball mill and ball mill it at 400 rpm for 120 minutes to obtain pretreated ternary lithium electrode powder.

[0037] (6) The pretreated ternary lithium electrode powder was placed in a crucible and placed in a tube furnace and nitrogen was introduced for 60 min. The temperature was increased to 700℃ at 5℃ / min and calcined for 120 min to obtain the repaired ternary lithium electrode powder.

[0038] Example 2

[0039] A rapid repair method for ternary lithium materials, the steps and the reagents and process parameters applicable to each step are the same as those in Example 1, the difference is that in step (2), the amount of silica added is 3% of the mass fraction of the electrode powder.

[0040] Example 3

[0041] A rapid repair method for ternary lithium materials, the steps and the reagents and process parameters applicable to each step are the same as those in Example 1, the difference is that in step (2), the amount of silica added is 5% of the mass fraction of the electrode powder.

[0042] Comparative Example 1

[0043] A rapid repair method for ternary lithium materials includes the following steps:

[0044] (1) Place the scrapped 523 ternary electrode in a beaker, add NMP at a solid-liquid ratio of 1:3, and stir the mixture for 40 minutes to allow the material to be fully sheared. After the PVDF in the electrode dissolves in NMP, sieve it through a 200-mesh standard sieve. The black powder precipitate that passes through the sieve is the desired electrode powder.

[0045] (2) Place the electrode powder in an oven and dry it with a forced air at 60°C for 24 hours. Then place it in a ball mill and ball mill it at 400 rpm for 120 minutes. Then place it in a crucible in a tube furnace and purge it with nitrogen for 60 minutes. Raise the temperature to 700°C at 5°C / min and calcine it for 120 minutes to obtain the repaired ternary lithium electrode powder.

[0046] Comparative Example 2

[0047] A rapid repair method for ternary lithium materials includes the following steps:

[0048] (1) The scrapped 523 ternary electrode sheets are placed in the crushing equipment for crushing, and then screened through a 200-mesh standard sieve. The black powder that passes through the sieve is the electrode sheet powder before repair.

[0049] (2) Add 3% by mass of silica to the pre-repair electrode powder, then mix it evenly with a high-speed mixer, place it in a muffle furnace, purge with nitrogen for 2 hours, start heating, raise the temperature to 450°C at a heating rate of 5°C / min, keep it at the temperature for 2 hours, and then cool it naturally to room temperature.

[0050] (3) The mixture is passed through a cyclone separator with a parameter of 6 Hz. The cyclone separator separates the material with a smaller specific gravity and the material with a larger specific gravity. The material with a smaller specific gravity is silica, and the material with a larger specific gravity is ternary lithium electrode powder.

[0051] (4) Place the material with a higher specific gravity on a ball mill and ball mill at 400 rpm for 120 min to obtain pretreated ternary lithium electrode powder;

[0052] (5) The pretreated ternary lithium electrode powder was placed in a crucible and placed in a tube furnace and nitrogen was introduced for 60 min. The temperature was increased to 700℃ at 5℃ / min and calcined for 120 min to obtain the repaired ternary lithium electrode powder.

[0053] Comparative Example 3

[0054] A rapid repair method for ternary lithium materials includes the following steps:

[0055] (1) The scrapped 523 ternary electrode sheets are placed in the crushing equipment for crushing, and then screened through a 200-mesh standard sieve. The black powder that passes through the sieve is the electrode sheet powder before repair.

[0056] (2) Mix the pre-repair electrode powder evenly with a high-speed mixer, place it in a muffle furnace, purge with nitrogen for 2 hours, start heating, raise the temperature to 450°C at a rate of 5°C / min, hold for 2 hours, and let it cool naturally to room temperature.

[0057] (3) Place the electrode powder in a beaker, add pure water at a solid-liquid ratio of 1:3, stir the mixture for 40 minutes to allow the material to be fully sheared, let it stand for 20 minutes and the carbon-containing substances in the material will be floated out by the buoyancy of the water, and the remaining material will naturally sink to the bottom of the liquid.

[0058] (4) Remove the suspended matter on the settled material, and wash the material multiple times according to step (3) to remove C, white carbon black and inorganic salts. After filtering the water, place the settled material in an oven, adjust the temperature to 60℃ and dry it with a forced air for 24 hours. Then place it on a ball mill and ball mill it at 400 rpm for 120 minutes to obtain pretreated ternary lithium electrode powder.

[0059] (5) The pretreated ternary lithium electrode powder was placed in a crucible and placed in a tube furnace and nitrogen was introduced for 60 min. The temperature was increased to 700℃ at 5℃ / min and calcined for 120 min to obtain the repaired ternary lithium electrode powder.

[0060] Comparative Example 4

[0061] A rapid repair method for ternary lithium materials includes the following steps:

[0062] (1) The scrapped 523 ternary electrode sheets are placed in the crushing equipment for crushing, and then screened through a 200-mesh standard sieve. The black powder that passes through the sieve is the electrode sheet powder before repair.

[0063] (2) Add 1% by mass of silica to the pre-repair electrode powder. The silica particle size is 20nm. Then mix it evenly with a high-speed mixer, place it in a muffle furnace, purge with nitrogen for 2 hours, start heating, heat to 450℃ at a heating rate of 5℃ / min, keep it at the temperature for 2 hours, and then cool it naturally to room temperature.

[0064] (3) The mixture is passed through a cyclone separator with a parameter of 6 Hz. The cyclone separator separates the material with a smaller specific gravity and the material with a larger specific gravity. The material with a smaller specific gravity is silica, and the material with a larger specific gravity is ternary lithium electrode powder.

[0065] (4) Place the material with a higher specific gravity in a beaker, add pure water at a solid-liquid ratio of 1:3, stir the mixture for 40 minutes to allow the material to be fully sheared, let it stand for 20 minutes and the carbon-containing substances in the material will be floated out by the buoyancy of the water, and the remaining material will naturally sink to the bottom of the liquid.

[0066] (5) Remove the suspended matter on the settled material. Wash the material multiple times according to step (4) to remove C, white carbon black and inorganic salts. After filtering the water, place the settled material in an oven and dry it with a forced air at 60℃ for 24 hours. Then place it on a ball mill and ball mill it at 400rpm for 120 minutes to obtain the repaired ternary lithium electrode powder.

[0067] Performance testing

[0068] 1. The pre-repair electrode powder and the repaired ternary lithium electrode powder from Example 2 were analyzed by scanning electron microscopy. The obtained SEM images are shown below. Figures 2-3 As shown, it can be observed that, Figure 2 The electrode powder shown in the image, due to repeated use, has collapsed, resulting in an uneven surface and affecting its electrical properties. However, as... Figure 3 The repaired material is smooth and flat, and its electrical properties have been restored.

[0069] 2. The carbon content of the repaired ternary lithium electrode powder and the unrepaired electrode powder prepared in the examples and comparative examples was determined by a carbon-sulfur analyzer. The carbon and sulfur in the sample were oxidized into carbon dioxide and sulfur dioxide gas by high temperature heating under oxygen-rich conditions. After treatment, the gas entered the corresponding absorption cell to absorb the corresponding infrared radiation. The detector then forwarded the signal, and the computer processed and output the results. The measurement results are shown in Table 1 below.

[0070] 3. The repaired ternary lithium electrode powder prepared in the examples and comparative examples was subjected to electrochemical performance testing according to GB / T 37201-2018 standard. The specific data were obtained by testing with equipment such as an electrochemical workstation. The test results are shown in Table 1 below.

[0071] Table 1 - Electrochemical performance of batteries made from ternary lithium electrode powders in Examples and Comparative Examples

[0072]

[0073] As shown in Table 1 above, in Examples 1-3, by adding silica during the calcination process, it can react with HF generated by the pyrolysis of PVDF in the electrode powder, thereby avoiding the strong oxidizing properties of HF from affecting the ternary lithium crystal structure and causing collapse. Moreover, as the amount of silica added during the calcination process increases, the C content in the repaired electrode powder gradually decreases. The charge-discharge capacity, efficiency, and electrical cycle stability after secondary calcination repair are significantly improved compared with those before repair, indicating that the repair effect is good.

[0074] In Comparative Example 1, after pre-dissolving the PVDF in the electrode powder before calcination, the initial charge-discharge specific capacity of the battery prepared from the electrode powder was lower than before the repair, while the initial charge-discharge efficiency remained basically unchanged before and after the repair. This indicates a poor repair effect because the PVDF in the electrode powder was not completely dissolved, resulting in residual F affecting the crystal structure. In Comparative Example 3, no silica was added during the first calcination process. The HF generated during the pyrolysis of PVDF would affect the ternary lithium crystal, causing structural collapse and affecting the electrical performance of the ternary lithium electrode powder. The electrical performance before and after the repair remained basically unchanged.

[0075] In Comparative Example 2, the carbon-containing substances and inorganic salts in the electrode powder were not cleaned and removed, which affected the electrical performance of the electrode powder. The C content in the electrode powder was high, and the improvement in electrical performance after battery preparation was not significant.

[0076] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. A method for fast repair of a ternary lithium material, characterized in that, The method comprises the following steps: (1) crushing and screening the ternary electrode sheet to obtain the pre-repair electrode sheet powder; (2) uniformly mixing the pre-repair electrode sheet powder with white carbon black, and performing primary roasting in an inert gas atmosphere, wherein the primary roasting temperature is 400-550℃; (3) separating the mixture after cooling by a cyclone separation device to obtain white carbon black with a smaller specific gravity and ternary lithium electrode sheet powder with a larger specific gravity; (4) adding water to the material with a larger specific gravity, stirring and mixing, and removing suspended substances after standing; (5) drying and ball milling the settled material after water filtration to obtain the pretreated ternary lithium electrode sheet powder; (6) performing secondary roasting on the pretreated ternary lithium electrode sheet powder in an inert gas atmosphere, wherein the secondary roasting temperature is 600-800℃, and the pretreated ternary lithium electrode sheet powder is obtained as the repair ternary lithium electrode sheet powder; In step (2), the white carbon black is added in an amount of 1%-10% of the mass fraction of the pre-repair electrode sheet powder. In step (2), the heating rate during the primary roasting process is 5-10℃ / min, and the holding time is 1.5-4h. In step (6), the heating rate during the secondary roasting process is 5-10℃ / min, and the holding time is 30-210min.

2. The method of claim 1, wherein the ternary lithium material is a lithium nickel cobalt manganese oxide (NCM) material. In step (1), the screening is performed by using a standard sieve with a mesh size of 150-500.

3. The method of claim 1, wherein the ternary lithium material is a lithium nickel cobalt aluminum oxide (NCA) material. In step (1), the ternary electrode sheet is one of 111, 523 or 622 ternary electrode sheets.

4. The method of claim 1, wherein the ternary lithium material is a lithium nickel cobalt aluminum oxide (NCA) material. In steps (2) and (6), the inert gas is nitrogen.

5. The method of claim 1, wherein the ternary lithium material is a lithium nickel cobalt aluminum oxide (NCA) material. In step (4), the water is added in a solid-liquid volume ratio of 1:(3-5), the stirring time is 30-60min, and the standing time is 10-20min.

6. The method of claim 1, wherein the ternary lithium material is a lithium nickel cobalt aluminum oxide (NCA) material. In step (5), the drying temperature is 40-100℃, and the drying time is 12-36h.

7. The method of claim 1, wherein the ternary lithium material is a lithium nickel cobalt aluminum oxide (NCA) material. In step (5), the ball milling rate is 200-500rmp / min, and the ball milling time is 30-210min.

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