An integrated end-to-end repair and regeneration method for waste cathode materials and its application.

Abstract

This application provides a method for the integrated repair and regeneration of waste cathode materials across the entire supply chain and its application. The method includes the following steps: (1) mixing waste cathode materials with a sodium source and calcining them to obtain sodium-doped waste cathode materials; (2) using the sodium-doped waste cathode materials as an adsorbent to adsorb carbon dioxide to obtain adsorbed cathode materials; (3) mixing the adsorbed cathode materials with a carbon-containing lithium source and sintering them to obtain repaired and regenerated cathode materials. In the recycling and repair process of this application, the sodium ions doped not only increase the carbon dioxide adsorption efficiency but also replace lithium, which can repair lithium defects and effectively improve the structural stability of the cathode materials, reduce the capacity loss of the electrode materials during charging and discharging, stabilize the valence of nickel ions, reduce lithium-nickel mixing, and to a certain extent suppress phase transitions during charging and discharging, thereby improving structural stability and electrochemical performance.

Description

Technical Field

[0001] This application relates to the field of resource recycling technology, such as a method for the integrated repair and regeneration of waste cathode materials across the entire supply chain and its application. Background Technology

[0002] Lithium-ion batteries are widely used in electronic devices and electric vehicles due to their advantages such as high energy density, long cycle life, and light weight. Ternary lithium-ion batteries are an important type of lithium-ion battery, possessing high energy density and good cycle performance, and currently occupy a dominant position in electric vehicles and other fields. The cathode materials of ternary lithium-ion batteries contain a rich variety and high content of valuable metal ions; therefore, efficient, environmentally friendly, and low-cost recycling of spent ternary lithium-ion batteries is of significant value. Currently, recycling technologies for ternary cathode materials (NCM) of lithium-ion batteries mainly include high-temperature metallurgy and direct recycling via hydrometallurgy. While high-temperature metallurgy and hydrometallurgy can return valuable metals such as lithium, cobalt, and nickel to the lithium-ion battery production chain, the complete destruction of the cathode particles reduces the high added value of the composite structure. The key process of direct recycling technology lies in repairing the compositional and structural defects of the degraded lithium-deficient cathode particles in retired lithium-ion batteries, thereby maximizing the preservation of the high added value of the cathode particles.

[0003] Current direct repair technologies mainly include hydrothermal methods, molten salt methods, and solid-state sintering methods. The hydrothermal method uses water as a solvent and lithium hydroxide as a carbon-containing lithium source to replenish lithium in waste lithium-ion ternary cathode materials under high temperature and pressure. After replenishment, excess lithium salt is removed by water washing and high-temperature sintering is performed. The capacity retention rate of ternary cathode materials repaired by the hydrothermal method after 100 cycles at 1C is 82%, lower than that of commercial ternary cathode materials. Furthermore, the hydrothermal method typically requires reaction temperatures above 220℃ and involves high pressure, posing certain risks. The molten salt method is similar to the solid-state sintering method, mixing waste lithium-ion battery ternary cathode materials with lithium salts and heating them. The free diffusion of lithium ions at high temperatures repairs lithium defects. However, the slow diffusion kinetics of lithium ions in solid-state regenerated materials prevent effective repair of lithium defects in the waste lithium-ion cathode materials, resulting in lower electrochemical capacity. Additionally, ternary materials are prone to problems such as battery gas generation, structural and interfacial phase transitions, and poor thermal stability due to lattice oxygen release.

[0004] CN114204013A discloses a method for directly repairing cathode materials from waste ternary lithium batteries, comprising the following steps: after low-temperature pretreatment, the active material is placed in distilled water and ultrasonically separated from the aluminum foil current collector to obtain cathode powder material; the obtained cathode powder material is uniformly mixed with a certain amount of ternary molten salt and a co-solvent, and lithium replenishment and impurity removal are performed simultaneously at low temperature; the washed and dried lithium replenishment powder is heat-treated under oxygen and high temperature conditions to obtain the repaired cathode material.

[0005] CN112909370A discloses a method for repairing ternary cathode materials in waste lithium batteries. The method involves heat-treating the disassembled waste cathode sheets, cooling them in a furnace to obtain waste cathode materials, cleaning the waste cathode materials with alkaline solution, drying them, then placing them in a crucible and heating them in a resistance furnace. After being removed, the materials are ground, pressed, and then placed in a resistance furnace for further heating. After cooling, the materials are removed again, ground, and pulverized to obtain the repaired cathode materials.

[0006] The above-mentioned solution resulted in a low electrochemical capacity of the ternary cathode material, and the ternary material was prone to problems such as battery gas generation, structural and interfacial phase transitions, and poor thermal stability due to oxygen release from the crystal lattice. Summary of the Invention

[0007] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.

[0008] This application provides a method for the integrated repair and regeneration of waste cathode materials across the entire supply chain and its application. In the recycling and repair process, the sodium ions doped in this application not only increase the carbon dioxide adsorption efficiency but also replace lithium. This not only repairs lithium defects but also effectively improves the structural stability of the cathode material, reduces capacity loss during charge and discharge, stabilizes the valence of nickel ions, reduces lithium-nickel mixing, and to a certain extent suppresses phase transitions during charge and discharge, thereby improving structural stability and electrochemical performance.

[0009] In a first aspect, embodiments of this application provide an integrated repair and regeneration method for waste cathode materials across the entire supply chain, the repair and regeneration method comprising the following steps:

[0010] (1) The waste cathode material is mixed with a sodium source and then calcined to obtain sodium-doped waste cathode material;

[0011] (2) Using the sodium-doped waste cathode material as an adsorbent, carbon dioxide adsorption treatment is carried out to obtain adsorbed cathode material;

[0012] (3) The adsorbed positive electrode material is mixed with a carbon-containing lithium source and sintered to obtain a repaired and regenerated positive electrode material.

[0013] This application involves heat-treating waste ternary materials while simultaneously doping them with sodium ions. This effectively activates the ternary materials. Furthermore, since the radius of the doped sodium ions is slightly larger than that of lithium ions, sodium doping can create defects in the structure, further enhancing the material's activity and increasing the rate of carbon dioxide adsorption, thus improving carbon dioxide resource utilization. The waste ternary materials, now doped with sodium and having adsorbed carbon dioxide, are then subjected to high-temperature calcination with carbon-containing lithium salts to replenish lithium and repair the materials. The carbon dioxide released during the heat treatment process modifies the surface of the ternary cathode material, creating oxygen vacancies near the surface. Before charging, some lattice oxygen in the ternary material can be extracted by CO2. The pre-activated surface layer of the modified sample with oxygen vacancies reduces the oxygen partial pressure on the surface, suppressing the release of gaseous oxygen during plateau charging.

[0014] Preferably, the sodium source in step (1) includes any one or a combination of at least two of sodium carbonate, sodium oxalate, or sodium nitrate.

[0015] Preferably, the molar ratio of the total transition metal in the waste cathode material to the molar ratio of sodium in the sodium source is 10:(0.5-1), for example: 10:0.5, 10:0.6, 10:0.8, 10:0.9 or 10:1, etc.

[0016] Preferably, the mixing method in step (1) includes ball milling.

[0017] Preferably, the ball milling time is 4 to 6 hours, for example: 4 hours, 4.5 hours, 5 hours, 5.5 hours or 6 hours.

[0018] Preferably, the calcination temperature in step (1) is 600 to 800°C, for example: 600°C, 650°C, 700°C, 750°C or 800°C.

[0019] Preferably, the calcination treatment time is 4 to 8 hours, for example: 4 hours, 5 hours, 6 hours, 7 hours or 8 hours.

[0020] Preferably, the temperature for the carbon dioxide adsorption treatment in step (2) is 500 to 700°C, for example: 500°C, 550°C, 600°C, 650°C or 700°C.

[0021] Preferably, the carbon dioxide adsorption treatment time is 2 to 6 hours, for example: 2 hours, 3 hours, 4 hours, 5 hours or 6 hours.

[0022] Preferably, the flow rate of the waste gas treated by adsorbing carbon dioxide is 5.5 to 15.5 L / min, for example: 5.5 L / min, 6 L / min, 8 L / min, 10 L / min or 15.5 L / min, etc.

[0023] Preferably, the carbon-containing lithium source in step (3) includes lithium carbonate and / or lithium oxalate.

[0024] Preferably, the molar ratio of the total transition metal in the adsorbed cathode material to the molar ratio of lithium in the carbon-containing lithium source is 1:(1 to 1.06), for example: 1:1, 1:1.01, 1:1.02, 1:1.04 or 1:1.06, etc.

[0025] Preferably, the mixing method in step (3) includes ball milling.

[0026] Preferably, the ball milling time is 4 to 6 hours, for example: 4 hours, 4.5 hours, 5 hours, 5.5 hours or 6 hours.

[0027] Preferably, the atmosphere for the sintering process in step (3) includes ammonia.

[0028] This application uses ammonia as the atmosphere for the sintering process, and ammonia can provide H₂O. + This maintains charge balance. Simultaneously, the formation of oxygen vacancies activates Li in tetrahedral positions and inhibits surface oxygen release, increasing the lithium-ion diffusion layer, stabilizing the transition metal layer, and reducing side reactions between the material, electrolyte, and oxygen. This results in the modified ternary material exhibiting higher discharge capacity and better rate performance.

[0029] Preferably, the sintering temperature is 700-900℃, for example: 700℃, 750℃, 800℃, 850℃ or 900℃.

[0030] Preferably, the sintering treatment time is 8 to 15 hours, for example: 8 hours, 9 hours, 10 hours, 12 hours or 15 hours.

[0031] Preferably, during the sintering process, the loading amount of the adsorbent positive electrode material is 5% to 15%, for example: 5%, 8%, 10%, 12% or 15%, etc.

[0032] As a preferred embodiment of this application, the repair and regeneration method includes the following steps:

[0033] (1) Mix waste cathode material with sodium source at M / Na = 10:(0.5~1) and ball mill for 4~6 hours, then calcine at 600~800℃ for 4~8 hours to obtain sodium-doped waste cathode material;

[0034] (2) The sodium-doped waste positive electrode material is placed in a carbon dioxide absorption tower as an adsorbent. At 500-700℃, carbon dioxide enters the absorption tower and comes into direct contact with the adsorbent to capture carbon dioxide. After adsorption for 2-6 hours, the adsorbent is taken out to obtain the adsorbed positive electrode material.

[0035] (3) The adsorbed positive electrode material and the carbon-containing lithium source are mixed and ball-milled at M / Li = 1:(1~1.06) for 4~6 hours, and sintered at 700~900℃ for 8~15 hours under an ammonia atmosphere to obtain the repaired and regenerated positive electrode material.

[0036] Secondly, embodiments of this application provide an application of the repair and regeneration method as described in the first aspect, wherein the repair and regeneration method is used for the repair and regeneration of lithium-ion battery cathode materials and carbon dioxide adsorption.

[0037] Compared with related technologies, the embodiments of this application have the following beneficial effects:

[0038] (1) In the recycling and repair process of this application, the sodium ions doped can not only increase the carbon dioxide adsorption efficiency, but also replace lithium. While repairing lithium defects, it can also effectively improve the structural stability of the cathode material, reduce the capacity loss of the electrode material during charging and discharging, stabilize the valence of nickel ions, reduce lithium-nickel mixing, and suppress phase transitions during charging and discharging to a certain extent, thereby improving structural stability and electrochemical performance.

[0039] (2) The battery made from the positive electrode material repaired and regenerated by the method described in this application can achieve a first charge capacity of more than 201.6 mAh / g, a first discharge capacity of more than 175.2 mAh / g, a first efficiency of more than 86.9%, and a capacity retention rate of more than 92.1% after 100 cycles of 1C charge and discharge.

[0040] After reading and understanding the detailed description, other aspects can be understood. Detailed Implementation

[0041] The technical solution of this application will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely to help understand this application and should not be regarded as specific limitations on this application.

[0042] The waste ternary cathode material used in the embodiments and comparative examples of this application is NCM811 cathode material.

[0043] Example 1

[0044] This embodiment provides a method for the integrated repair and regeneration of waste cathode materials across the entire supply chain. The repair and regeneration method includes the following steps:

[0045] (1) The ternary material and sodium carbonate were put into a double planetary ball mill at M / Na = 10: 0.7 and ball milled at 200 rpm for 5 hours. The ball milling dispersant was anhydrous ethanol, and its volume was twice that of the powder. The mixture was calcined at 700℃ for 6 hours to obtain sodium-doped waste cathode material.

[0046] (2) The sodium-doped waste cathode material is placed in a carbon dioxide absorption tower as an adsorbent. At 600°C, carbon dioxide enters the absorption tower and comes into direct contact with the adsorbent to capture carbon dioxide. The waste gas flow rate is 10.5 L / min. After adsorption for 4 hours, the adsorbent is taken out to obtain the adsorbed cathode material.

[0047] (3) The adsorbed positive electrode material and lithium carbonate were mixed and ball-milled at M / Li = 1:1.03 for 5 hours. The ball-milled material was then filled into a sealed container at a volume ratio of 10% and sintered at 800°C for 11 hours under an ammonia atmosphere to obtain the repaired and regenerated positive electrode material.

[0048] Example 2

[0049] This embodiment provides a method for the integrated repair and regeneration of waste cathode materials across the entire supply chain. The repair and regeneration method includes the following steps:

[0050] (1) The ternary material and sodium oxalate were placed together in a double planetary ball mill at a ratio of M / Na = 10:1 and ball milled at 200 rpm for 5 hours. The ball milling dispersant was anhydrous ethanol, with a volume twice that of the powder. The mixture was calcined at 600℃ for 8 hours to obtain sodium-doped waste cathode material.

[0051] (2) The sodium-doped waste cathode material is placed in a carbon dioxide absorption tower as an adsorbent. At 500°C, carbon dioxide enters the absorption tower and comes into direct contact with the adsorbent to capture carbon dioxide. The waste gas flow rate is 5.5 L / min. After adsorption for 6 hours, the adsorbent is taken out to obtain the adsorbed cathode material.

[0052] (3) The adsorbed positive electrode material and lithium oxalate were mixed and ball-milled at M / Li = 1:1 for 5 hours. The ball-milled material was then filled into a sealed container at a volume ratio of 5%, and sintered at 700°C for 15 hours under an ammonia atmosphere to obtain the repaired and regenerated positive electrode material.

[0053] Example 3

[0054] This embodiment provides a method for the integrated repair and regeneration of waste cathode materials across the entire supply chain. The repair and regeneration method includes the following steps:

[0055] (1) The ternary material and sodium nitrate were put into a double planetary ball mill at M / Na = 10: 0.5 and ball milled at 200 rpm for 5 hours. The ball milling dispersant was anhydrous ethanol, and its volume was twice that of the powder. The mixture was calcined at 800℃ for 4 hours to obtain sodium-doped waste cathode material.

[0056] (2) The sodium-doped waste cathode material is placed in a carbon dioxide absorption tower as an adsorbent. At 700°C, carbon dioxide enters the absorption tower and comes into direct contact with the adsorbent to capture carbon dioxide. The waste gas flow rate is 15.5 L / min. After adsorption for 2 hours, the adsorbent is taken out to obtain the adsorbed cathode material.

[0057] (3) The adsorbed positive electrode material and lithium oxalate were mixed and ball-milled at M / Li = 1:1.06 for 5 hours. The ball-milled material was then filled into a sealed container at a volume ratio of 15% and sintered at 900°C for 8 hours under an ammonia atmosphere to obtain the repaired and regenerated positive electrode material.

[0058] Example 4

[0059] The only difference between this embodiment and Embodiment 1 is that M / Na = 10:0.3, while the other conditions and parameters are exactly the same as in Embodiment 1.

[0060] Example 5

[0061] The only difference between this embodiment and Embodiment 1 is that M / Na = 10:1.2; all other conditions and parameters are exactly the same as in Embodiment 1.

[0062] Comparative Example 1

[0063] The only difference between this comparative example and Example 1 is that no sodium source is added in step (1), while the other conditions and parameters are exactly the same as in Example 1.

[0064] Comparative Example 2

[0065] The only difference between this comparative example and Example 1 is that step (2) does not adsorb carbon dioxide; all other conditions and parameters are exactly the same as in Example 1.

[0066] Comparative Example 3

[0067] The only difference between this comparative example and Example 1 is that in step (3), lithium carbonate is replaced with lithium hydroxide, while the other conditions and parameters are exactly the same as in Example 1.

[0068] Comparative Example 4

[0069] The only difference between this comparative example and Example 1 is that ammonia is not used as the sintering atmosphere in step (3), while the other conditions and parameters are exactly the same as in Example 1.

[0070] Performance testing:

[0071] The positive electrode material obtained in Example 1 and the comparative example was mixed with the conductive active material SuperP and the binder PVDF in a ratio of 90:5:5 to form a slurry, which was then uniformly coated onto aluminum foil to prepare a positive electrode sheet. A high-purity lithium sheet was used as the negative electrode, and a Celgard 2400 polypropylene membrane was used as the separator. The electrolyte was a 1 mol / L LiPF6 dissolved in a mixed solvent of EC and DMC (volume ratio 1:1). The cells were assembled into CR2032 coin cells in a vacuum glove box, and then electrochemical tests were performed. Charge-discharge tests were conducted using a LAND-2001 LAND test system, with a charge-discharge range of 3.0-4.3V and a temperature of 25℃. The test results are shown in Table 1.

[0072] Table 1

[0073]

[0074] As can be seen from Table 1, as obtained from Examples 1-3, the battery made from the cathode material repaired and regenerated by the method described in this application can achieve a first-charge capacity of over 201.6 mAh / g, a first-discharge capacity of over 175.2 mAh / g, a first-efficiency of over 86.9%, and a capacity retention rate of over 92.1% after 100 cycles of 1C charge-discharge.

[0075] A comparison of Examples 1 and 4-5 shows that the amount of sodium source added in the repair and regeneration method described in this application affects the repair effect. The repair and regeneration effect is better when the molar ratio of the total molar amount of transition metals in the waste cathode material to the molar ratio of sodium element neutralized in the sodium source is controlled at 10:(0.5~1). If the amount of sodium source added is too low, the content of sodium ions in the cathode material will be too low, which will not play a role in stabilizing the material structure. If the amount of sodium source added is too high, too many sodium ions will occupy lithium sites, thereby affecting lithium ion diffusion and reducing the material cycle performance.

[0076] As can be seen from the comparison between Example 1 and Comparative Example 1, this application can effectively activate ternary materials by heat-treating the waste ternary materials while doping them with sodium ions. In addition, since the radius of the doped sodium ions is slightly larger than that of lithium ions, the doping of sodium can create defects in the structure, which is beneficial to further improve the activity of the material, increase the rate of carbon dioxide adsorption, and increase the resource utilization rate of carbon dioxide.

[0077] As can be seen from the comparison between Example 1 and Comparative Example 2, the present application uses sodium-doped waste cathode material to adsorb sodium, and the surface carbon dioxide modification inhibits the irreversible oxygen release in the first cycle, which greatly improves the voltage decay problem during the cycle.

[0078] Comparing Example 1 and Comparative Example 3, it can be seen that this application involves high-temperature calcination of waste cathode material that has adsorbed carbon dioxide and is doped with sodium, along with carbon-containing lithium salts, to perform lithium replenishment and repair on the waste ternary material. The carbon dioxide released during the heat treatment process can modify the surface of the ternary cathode material, forming oxygen vacancies in the near-surface region. Before charging, some lattice oxygen in the ternary material can be extracted by CO2. The pre-activated surface layer of the modified sample with oxygen vacancies reduces the oxygen partial pressure on the surface, which can suppress the release of gaseous oxygen during plateau charging.

[0079] As can be seen from the comparison between Example 1 and Comparative Example 4, the sintering of this application is carried out under an ammonia atmosphere, and ammonia can provide H2O. + This maintains charge balance. Simultaneously, the formation of oxygen vacancies activates Li in tetrahedral positions and inhibits surface oxygen release, increasing the lithium-ion diffusion layer, stabilizing the transition metal layer, and reducing side reactions between the material, electrolyte, and oxygen. This results in the modified ternary material exhibiting higher discharge capacity and better rate performance.

[0080] The applicant declares that the above description is only a specific implementation of this application, but the protection scope of this application is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application fall within the protection and disclosure scope of this application.

Claims

1. A method for the integrated repair and regeneration of waste ternary cathode materials across the entire supply chain, comprising the following steps: (1) The waste ternary cathode material is mixed with a sodium source and then calcined to obtain sodium-doped waste ternary cathode material; (2) Using the sodium-doped waste ternary cathode material as an adsorbent, carbon dioxide adsorption treatment is carried out to obtain adsorbed cathode material; (3) The adsorbed positive electrode material is mixed with a carbon-containing lithium source and sintered to obtain a repaired and regenerated positive electrode material; The atmosphere for the sintering process in step (3) includes ammonia; The sintering temperature is 700–900°C. The sintering process takes 8 to 15 hours.

2. The repair and regeneration method as described in claim 1, wherein, The sodium source in step (1) includes any one or a combination of at least two of sodium carbonate, sodium oxalate, or sodium nitrate.

3. The repair and regeneration method as described in claim 1 or 2, wherein, The total molar ratio of transition metals in the waste ternary cathode material to sodium in the sodium source is 10:(0.5-1).

4. The repair and regeneration method according to any one of claims 1-2, wherein, The mixing method described in step (1) includes ball milling.

5. The repair and regeneration method as described in claim 4, wherein, The ball milling time is 4 to 6 hours.

6. The repair and regeneration method according to any one of claims 1-2, wherein, The calcination temperature in step (1) is 600–800°C.

7. The repair and regeneration method according to any one of claims 1-2, wherein, The calcination treatment time is 4 to 8 hours.

8. The repair and regeneration method according to any one of claims 1-2, wherein, The temperature for the carbon dioxide adsorption treatment in step (2) is 500–700°C; The carbon dioxide adsorption treatment time is 2-6 hours; The flow rate of the waste gas treated by adsorbing carbon dioxide is 5.5 to 15.5 L / min.

9. The repair and regeneration method according to any one of claims 1-2, wherein, The carbon-containing lithium source in step (3) includes lithium carbonate and / or lithium oxalate.

10. The repair and regeneration method according to any one of claims 1-2, wherein, The total molar amount of transition metal in the adsorbed cathode material and the molar ratio of lithium in the carbon-containing lithium source are 1:(1~1.06).

11. The repair and regeneration method according to any one of claims 1-2, wherein, The mixing method described in step (3) includes ball milling; The ball milling time is 4 to 6 hours.

12. The repair and regeneration method according to any one of claims 1-2, During the sintering process, the loading amount of the adsorbent cathode material is 5-15%.

13. The repair and regeneration method according to any one of claims 1-2, comprising the following steps: (1) Mix waste ternary cathode material with sodium source at M / Na = 10:(0.5~1) and ball mill for 4~6 hours, then calcine at 600~800℃ for 4~8 hours to obtain sodium-doped waste ternary cathode material; (2) The sodium-doped waste ternary cathode material is placed in a carbon dioxide absorption tower as an adsorbent. At 500-700℃, carbon dioxide enters the absorption tower and comes into direct contact with the adsorbent to capture carbon dioxide. After adsorption for 2-6 hours, the adsorbent is taken out to obtain the adsorbed cathode material. (3) The adsorbed positive electrode material and the carbon-containing lithium source are mixed and ball-milled at M / Li = 1:(1~1.06) for 4~6 hours, and sintered at 700~900℃ for 8~15 hours under an ammonia atmosphere to obtain the repaired and regenerated positive electrode material.

14. An application of the repair and regeneration method as described in any one of claims 1-2, wherein, The repair and regeneration method is used for the repair and regeneration of positive electrode materials in lithium-ion batteries and for carbon dioxide adsorption.

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