Method for recovering positive electrode of waste lithium ion battery

Abstract

The application belongs to the field of electrode material recycling, and particularly relates to a synergistic intensifier for improving water immersion of waste positive electrode material, which comprises component A and component B; the component A comprises FeS2; and the component B comprises a water-soluble ferric salt. The application also comprises application of the combined additive to auxiliary recycling and regeneration of the positive electrode material. The combined intensifier can achieve excellent water immersion effect without activation of the iron sulfide, and is also conducive to improving the electrochemical performance of the regenerated positive electrode material.

Description

Technical Field

[0001] This invention belongs to the field of battery waste recycling, specifically relating to the recycling of waste lithium battery materials. Background Technology

[0002] Lithium-ion batteries are widely used in mobile electronic devices and electric vehicles due to their high energy density, good cycle performance, and low memory effect. However, their performance declines after 1000 cycles, meaning that the lifespan of lithium-ion batteries rarely exceeds 5 years, resulting in a large number of waste lithium-ion batteries. The numerous valuable elements they contain, if not recycled, will cause significant resource waste and environmental pollution.

[0003] Regarding the recycling of waste cathode materials, the inventors previously proposed a pyrite-assisted cathode leaching approach. However, early research revealed that directly using pyrite to assist cathode leaching was not ideal, requiring activation treatment using high-temperature, high-pressure, and high-energy ball milling processes. For example, Chinese patent CN115558800A discloses a cathode recycling process in which waste cathode materials and FeS2-containing materials are activated with an activation solution at any stage before, during, or after ball milling; the activation solution is a mixture of water-soluble organic solvent and water; the activated material is then subjected to acid leaching to obtain a leachate enriched with the metal elements of the waste cathode materials. For example, Chinese patent document CN115652082A discloses a FeS2-assisted spheroidization-oxidation roasting method for lithium extraction from waste cathode materials. The method involves spheroidizing waste cathode materials, FeS2 source, spheroidizing binder, and solvent in a spheroidizing machine to obtain green pellets; roasting the green pellets in an oxygen-containing atmosphere to obtain roasted material; and immersing the roasted material in water to obtain lithium extraction solution and transition metal slag. The roasting temperature is 200–300°C; the solvent is an alcohol-containing aqueous solution, wherein the alcohol volume content is 20–70 vol%. Chinese patent document CN116565368A discloses a method for processing waste electrode materials. The method involves ball milling an FeS2 source and then calcining it under a protective atmosphere at a temperature above 550°C to obtain an activated FeS2 source. The waste electrode material containing waste cathode material and the activated FeS2 source are then slurried with water, heated and pressurized to a subcritical state, and subjected to heat and pressure treatment before depressurization, cooling, and solid-liquid separation to obtain a leachate enriched with metal elements from the cathode material. The weight ratio of the activated FeS2 source to the waste electrode material is above 0.5. The subcritical state temperature is above 180°C, and the pressure is above 1 MPa. For example, Chinese patent document CN117013129A discloses a method for recycling waste lithium-ion battery cathode materials. The method involves calcining a mixture containing waste lithium-ion battery cathode materials and pyrite at a temperature of 400–700°C in a carbon dioxide atmosphere, followed by water leaching and solid-liquid separation to obtain a metal leachate. The weight ratio of the cathode active material in the waste lithium-ion battery cathode material to FeS2 in the pyrite is 1:1–5.

[0004] In summary, most existing pyrite-assisted leaching processes require activation treatment through roasting, ball milling, and high oxygen pressure processes, and there are no reports of non-activation-assisted water leaching processes. Summary of the Invention

[0005] In view of the problems faced in the recycling of waste lithium-ion battery cathodes, the present invention aims to provide a synergistic enhancer to improve the water immersion effect of waste cathode materials without activation.

[0006] The second objective of this invention is to provide a method for treating waste cathode materials by water immersion using the aforementioned synergistic reinforcing agent, aiming to provide a method that can achieve excellent water immersion results without additional activation.

[0007] The third objective of this invention is to provide a method for regenerating waste cathode materials using the aforementioned synergistic reinforcing agent, aiming to efficiently recover elements from waste cathodes and utilize these elements to hybridize the regenerated cathode active material, thereby improving the electrochemical performance of the regenerated cathode material.

[0008] A synergistic reinforcing agent for improving the water immersion of waste cathode materials, comprising component A and component B;

[0009] Component A includes FeS2;

[0010] Component B includes water-soluble ferric salts.

[0011] This invention innovatively demonstrates that combining components A and B can unexpectedly achieve a synergistic effect, enhancing the water immersion treatment of waste cathode materials without requiring activation of iron sulfide. The process of this invention provides a non-enhanced and acid-free water immersion process that strengthens the water immersion effect of waste cathode materials and also facilitates their regeneration into recycled cathode materials with higher electrochemical performance.

[0012] In this invention, component A is at least one of minerals containing FeS2 and solid waste.

[0013] Preferably, the FeS2 content in component A is 50 wt% or more, more preferably 80 wt% or more, and even more preferably 95 wt% or more.

[0014] In this invention, the water-soluble ferric salt in component B is at least one of ferric sulfate, ferric chloride, ferric nitrate, ferric acetate, ferric citrate, and ferric gluconate.

[0015] Preferably, in component B, the content of water-soluble trivalent iron salt is 50 wt% or more, more preferably 80 wt% or more, and even more preferably 95 wt% or more.

[0016] In this invention, the weight ratio of FeS2 in component A to the water-soluble trivalent iron salt in component B is 1:3 to 20, preferably 1:5 to 15; more preferably 1:7 to 10.

[0017] The present invention also provides a method for recovering metal elements from waste cathode materials using the aforementioned synergistic reinforcing agent. The waste cathode materials and the aforementioned synergistic reinforcing agent are mixed and subjected to water immersion treatment, followed by solid-liquid separation to obtain an aqueous immersion solution enriched with metal elements from the waste cathode materials.

[0018] In this invention, thanks to the use of the aforementioned synergistic reinforcing agent, the water immersion of waste cathode materials can be achieved without the need for activation processes such as high temperature and high pressure, thereby improving the water immersion effect. In addition, it is also beneficial to utilize the beneficial dopants in the waste cathode materials, and then regenerate them to obtain recycled materials with higher electrochemical performance.

[0019] In this invention, the waste cathode material can be an electrode material obtained by stripping it from the cathode of a waste lithium-ion battery.

[0020] In this invention, there are no special requirements for the type of active material in the waste cathode material. For example, the waste cathode material includes at least one waste active material selected from LiXO2, LiY2O2, and LiZPO4; X and Y each include at least one of Ni, Co, and Mn; and Z includes at least one of Fe and Mn.

[0021] In this invention, the waste positive electrode material may also contain at least one of a conductive agent, a binder, and a negative electrode material;

[0022] In this invention, the content of waste active material in the waste cathode material is above 50 wt%.

[0023] In this invention, the weight ratio of the waste cathode material and the synergistic reinforcing agent (based on the active components in components A and B) is 1:3 to 20, preferably 1:5 to 15; more preferably 1:7 to 10.

[0024] In this invention, the solid-liquid ratio during the water immersion stage is 20–50 mL / g;

[0025] Preferably, the temperature during the water immersion stage is below 90°C. Considering efficiency, it can be further set to 60-90°C, or even further set to 70-80°C.

[0026] Preferably, the immersion time is 0.5 hours or more, more preferably 1 to 4 hours, and even more preferably 1 to 3 hours.

[0027] The present invention also provides a method for regenerating waste cathode materials. The waste cathode materials are leached using the recycling method described in the present invention to obtain an aqueous leachate. The pH of the aqueous leachate is controlled in advance to be 3.5-4.5, and iron removal treatment is performed. Solid-liquid separation is then performed to obtain an iron-removed liquid.

[0028] Subsequently, the proportion of metal elements in the iron removal liquid was adjusted, and co-precipitation was carried out under conditions of pH 10 or above (preferably 10.5 to 13.5) to obtain transition metal hydroxide and lithium-containing precipitate mother liquor. The lithium-containing precipitate mother liquor was then subjected to carbonation precipitation to obtain lithium carbonate.

[0029] The obtained transition metal hydroxide and lithium carbonate composite carbonization is used to prepare a regenerated positive electrode active material.

[0030] In this invention, iron removal, drying, and calcination can be performed based on known processes.

[0031] The precipitant used in the iron removal and precipitation stages is a mixture of ammonia and alkali.

[0032] In this invention, carbon can be added or sintering can be carried out in a carbon-containing atmosphere before roasting, as needed.

[0033] In this invention, the temperature and time parameters of the calcination process can be adjusted according to the type of recycled material and based on existing parameters and principles.

[0034] The present invention also includes the application of the regenerated positive electrode active material to prepare lithium-ion batteries.

[0035] The present invention also provides a lithium-ion battery comprising the regenerated positive electrode active material, and further, the positive electrode sheet of the lithium-ion battery comprises the regenerated positive electrode active material.

[0036] In this invention, the lithium-ion battery, apart from the regenerated cathode material, can have other components, parts, and parameters that are conventional or can be obtained by adjusting based on known principles.

[0037] Beneficial effects

[0038] This invention innovatively combines components A and B, unexpectedly achieving a synergistic effect. This allows for enhanced water immersion treatment of waste cathode materials without the need for activation of iron sulfide. The process of this invention provides a non-enhanced and acid-free water immersion process that strengthens the water immersion effect of waste cathode materials and facilitates the regeneration of cathode materials with higher electrochemical performance. Furthermore, the method of this invention better preserves the electrochemically beneficial components in the waste materials, thus unexpectedly further improving the electrochemical performance of the regenerated cathode. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to specific embodiments, but the present invention is not limited to the following embodiments.

[0040] In this invention, there are no special requirements for the content of active material in the waste lithium-ion battery cathode material. Considering the economics of the process, the content is preferably above 50 wt.%. In the following examples, unless otherwise stated, the content of active material is 85-90 wt.%. In the following examples, the weight of the waste cathode material is based on the weight of the active material.

[0041] In the following examples, components A and B can be any materials containing the active ingredients. Considering the simplicity of the process and the scale of the laboratory, relatively pure materials can be used. For example, in the following examples, unless otherwise stated, the FeS2 content in the pyrite can be 95-96%. In addition, in the following examples, the amount of pyrite used is based on the weight of FeS2 therein.

[0042] In this invention, component B can be made from analytically pure raw materials.

[0043] Example 1:

[0044] Step (1): Stripping: The waste power nickel cobalt manganese acid (NCM close to 1:1:1) lithium battery was placed in 2 mol / L salt water for 30 h discharge treatment. The discharged battery was dried at 85℃, and the positive electrode and negative electrode were separated. The positive electrode was soaked in N-methylpyrrolidone, the current collector in the positive electrode was separated, and the waste positive electrode material powder was obtained by filtration, washing and drying.

[0045] Step (2): Leaching: The waste cathode material powder and the synergistic reinforcing agent (including pyrite (component A) and ferric sulfate (component B) in a weight ratio of 1:10) are placed in a water bath at a mass ratio of 1:10. Water is added (liquid-solid ratio of 30 ml / g, based on the weight of the waste cathode material). After mixing evenly, the mixture is leached at 70°C for 2 hours to obtain a solution rich in valuable metal ions. The leaching rate of valuable metals is determined to be 99.8% for Ni, 99.6% for Co, 99.7% for Mn, and 99.8% for Li.

[0046] Step (3): Stepwise precipitation: For the above solution, add NaOH-NH3·H2O to adjust the pH to 4 to remove iron and aluminum. After filtration, adjust the NCM ratio to 1:1:1 and add NaOH-NH3·H2O to adjust the pH to 11 to precipitate nickel, cobalt and manganese. Add Na2CO3 to the filtrate after filtration and evaporate to crystallize Li2CO3.

[0047] Step (4): Regeneration: The obtained nickel-cobalt-manganese coprecipitate is mixed with Li2CO3 (Li:NCM molar ratio of 1.02:1).

[0048] After being mixed evenly, the mixture was annealed at 800℃ for 10 hours to obtain the regenerated positive electrode active material.

[0049] The active material (Super P:PVDF) was dry-milled for half an hour in a ratio of 8:1:1, then wet-milled until uniform. This uniformly coated aluminum foil and dried in a vacuum oven at 80°C. In a glove box, 1M LiPF6 was used as the electrolyte (EC:DEC:EMC = 1:1:1), and a Celgard 2400 polypropylene membrane was used as the separator. Using lithium as the counter electrode, the regenerated cathode at a rate of 0.5C at room temperature exhibited a reversible capacity of 236 mAh / g.

[0050] Example 2

[0051] Compared with Example 1, the only difference is that lithium nickel cobalt manganese oxide is replaced with lithium cobalt oxide, while other operations and parameters are the same as in Example 1.

[0052] In step (4), the leaching rates of valuable metals were 99.1% for Co and 99.3% for Li. 1M LiPF6 was used as the electrolyte (EC:DEC:EMC = 1:1:1) in a glove box, and a Celgard 2400 polypropylene membrane was used as the separator. With lithium as the counter electrode, the positive electrode exhibited a reversible capacity of 192 mAh / g at a 0.5C rate regeneration at room temperature.

[0053] Example 3

[0054] Compared with Example 1, the only difference is that the positive electrode material is replaced with lithium manganese oxide, while the other operations and parameters are the same as in Example 1.

[0055] In step (4), the leaching rates of the valuable metals were 99.5% for Mn and 99.6% for Li. 1M LiPF6 was used as the electrolyte (EC:DEC:EMC = 1:1:1) in a glove box, and a Celgard 2400 polypropylene membrane was used as the separator. With lithium as the counter electrode, the positive electrode exhibited a reversible capacity of 180 mAh / g at a 0.5C rate regeneration at room temperature.

[0056] Example 4

[0057] Compared with Example 1, the only difference is that the leaching temperature is changed to 80°C, while the other operations and parameters are the same as in Example 1.

[0058] In step (4), the leaching rates of the valuable metals were 99.9% for Ni, 99.8% for Co, 99.7% for Mn, and 99.9% for Li. 1M LiPF6 was used as the electrolyte (EC:DEC:EMC = 1:1:1) in a glove box, and a Celgard 2400 polypropylene membrane was used as the separator. With lithium as the counter electrode, the positive electrode exhibited a reversible capacity of 250 mAh / g at a 0.5C rate regeneration at room temperature.

[0059] Example 5

[0060] Compared with Example 1, the only difference is that ferric sulfate is replaced with an equal weight of ferric chloride, while other operations and parameters are the same as in Example 1.

[0061] In step (4), the leaching rates of the valuable metals were 99.7% for Ni, 99.6% for Co, 99.7% for Mn, and 99.8% for Li. 1M LiPF6 was used as the electrolyte (EC:DEC:EMC = 1:1:1) in a glove box, and a Celgard 2400 polypropylene membrane was used as the separator. With lithium as the counter electrode, the positive electrode exhibited a reversible capacity of 245 mAh / g at a 0.5C rate regeneration at room temperature.

[0062] Example 6

[0063] Compared with Example 1, the only difference is that the weight ratio of component A to component B is adjusted to 1:8, and other operations and parameters are the same as in Example 1.

[0064] In step (4), the leaching rates of the valuable metals were 99.4% for Ni, 99.5% for Co, 99.3% for Mn, and 99.7% for Li. 1M LiPF6 was used as the electrolyte (EC:DEC:EMC = 1:1:1) in a glove box, and a Celgard 2400 polypropylene membrane was used as the separator. With lithium as the counter electrode, the positive electrode exhibited a reversible capacity of 239 mAh / g at a 0.5C rate regeneration at room temperature.

[0065] Example 7

[0066] Compared with Example 1, the only difference is that the ratio of waste positive electrode to synergistic reinforcing agent is set to 1:7, while other operations and parameters are the same as in Example 1.

[0067] In step (4), the leaching rates of the valuable metals were 99.5% for Ni, 99.8% for Co, 99.7% for Mn, and 99.9% for Li. 1M LiPF6 was used as the electrolyte (EC:DEC:EMC = 1:1:1) in a glove box, and a Celgard 2400 polypropylene membrane was used as the separator. With lithium as the counter electrode, the positive electrode exhibited a reversible capacity of 249 mAh / g at a 0.5C rate regeneration at room temperature.

[0068] Comparative Example 1

[0069] Compared with Example 1, the only difference is that FeS2 is not added to the synergistic reinforcing agent, the amount of the remaining component B is the same as that of the synergistic reinforcing agent in Example 1, and other operations and parameters are the same as in Example 1.

[0070] In step (2), the leaching rates of each valuable metal were 44.8% for Ni, 48.9% for Co, 55.7% for Mn, and 68.7% for Li.

[0071] Comparative Example 2

[0072] Compared with Example 1, the only difference is that Fe2(SO4)3 is not added to the synergistic reinforcing agent, the amount of the remaining component A is the same as that of the synergistic reinforcing agent in Example 1, and other operations and parameters are the same as in Example 1.

[0073] In step (2), the leaching rates of each valuable metal are 30.7% for Ni, 33.1% for Co, 39.7% for Mn, and 50.7% for Li.

[0074] Comparative Example 3

[0075] Compared with Example 1, the only difference is that Fe2(SO4)3 is replaced with an equal weight of Al2(SO4)3, and the other operations and parameters are the same as in Example 1.

[0076] In step (2), the leaching rates of each valuable metal were 8.4% for Ni, 10.7% for Co, 15.3% for Mn, and 37.8% for Li.

[0077] Comparative Example 4

[0078] Compared with Example 1, the only difference is that Fe2(SO4)3 is replaced with an equal weight of FeSO4, and the other operations and parameters are the same as in Example 1.

[0079] In step (2), the leaching rates of each valuable metal are 50.3% for Ni, 53.9% for Co, 44.9% for Mn, and 65.3% for Li.

Claims

1. A synergistic reinforcing agent for improving the water immersion of waste cathode materials, characterized in that, Includes component A and component B; Component A includes FeS2; Component B includes water-soluble ferric salts; The waste cathode material is an electrode material obtained by stripping from the cathode of a waste lithium-ion battery; the waste cathode material includes at least one waste active material selected from LiXO2, LiY2O2, and LiZPO4; X and Y each include at least one of Ni, Co, and Mn; Z includes at least one of Fe and Mn. The FeS2 content in component A is above 50 wt%; In component B, the water-soluble ferric salt is at least one of ferric sulfate, ferric chloride, ferric nitrate, ferric acetate, ferric citrate, and ferric gluconate. In component B, the content of water-soluble ferric salt is above 50 wt%; The weight ratio of FeS2 in component A to the water-soluble trivalent iron salt in component B is 1:3~20.

2. The synergistic reinforcing agent for improving the water immersion of waste cathode materials as described in claim 1, characterized in that, The component A is at least one of the minerals containing FeS2 and solid waste.

3. The synergistic reinforcing agent for improving the water immersion of waste cathode materials as described in claim 2, characterized in that, The FeS2 content in component A is above 80wt%.

4. The synergistic reinforcing agent for improving the water immersion of waste cathode materials as described in claim 3, characterized in that, The FeS2 content in component A is above 95wt%.

5. The synergistic reinforcing agent for improving the water immersion of waste cathode materials as described in claim 1, characterized in that, In component B, the content of water-soluble ferric salt is above 80 wt%.

6. The synergistic reinforcing agent for improving the water immersion of waste cathode materials as described in claim 5, characterized in that, In component B, the content of water-soluble ferric salt is above 95 wt%.

7. The synergistic reinforcing agent for improving the water immersion of waste cathode materials as described in claim 1, characterized in that, The weight ratio of FeS2 in component A to the water-soluble trivalent iron salt in component B is 1:5~15.

8. The synergistic reinforcing agent for improving the water immersion of waste cathode materials as described in claim 7, characterized in that, The weight ratio of FeS2 in component A to the water-soluble trivalent iron salt in component B is 1:7~10.

9. A method for recovering metal elements from waste cathode materials using the synergistic reinforcing agent described in any one of claims 1 to 8, characterized in that, The waste cathode material and the aforementioned synergistic reinforcing agent are mixed and subjected to water immersion treatment, followed by solid-liquid separation to obtain an aqueous immersion solution enriched with metal elements from the waste cathode material.

10. The method as described in claim 9, characterized in that, The waste cathode material also includes at least one of a conductive agent and a binder.

11. The method according to any one of claims 9 to 10, characterized in that, The solid-liquid ratio during the water immersion stage is 20~50mL / g.

12. The method according to any one of claims 9 to 10, characterized in that, The temperature during the water immersion stage is below 90°C.

13. The method according to any one of claims 9 to 10, characterized in that, The immersion time should be more than 0.5 hours.

14. The method as described in claim 13, characterized in that, The immersion time is 1 to 4 hours.

15. A method for regenerating waste cathode materials, characterized in that, The waste positive electrode material is leached using the method described in any one of claims 9 to 14 to obtain an aqueous leaching solution. The pH of the aqueous leaching solution is pre-controlled to be 3.5 to 4.5, and iron removal treatment is performed. Solid-liquid separation is then performed to obtain an iron-removed solution. Subsequently, the proportion of metal elements in the iron removal liquid was adjusted, and co-precipitation was carried out under conditions above pH 10 to obtain transition metal hydroxide and lithium-containing precipitate mother liquor. The lithium-containing precipitate mother liquor was then precipitated by carbonation to obtain lithium carbonate. The obtained transition metal hydroxide and lithium carbonate were mixed and calcined to obtain a regenerated positive electrode active material.

16. A lithium secondary battery, characterized in that, The regenerated positive electrode active material obtained by the regeneration method of claim 15.