Fe7S8-assisted alkaline leaching method for lithium extraction from waste lithium-containing cathode active materials, as well as recycling and regeneration methods
By using the Fe7S8-assisted alkaline leaching method to treat waste lithium-ion battery cathode materials at normal pressure and low temperature, the problems of poor pre-extraction lithium effect and transition metal loss were solved, and efficient lithium recovery and regeneration were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CENT SOUTH UNIV
- Filing Date
- 2024-01-08
- Publication Date
- 2026-08-04
AI Technical Summary
Existing technologies for recycling cathode materials from waste lithium-ion batteries have poor lithium extraction efficiency under normal pressure and significant loss of transition metals, especially when processed under high-temperature conditions.
A lithium extraction method assisted by Fe7S8 was adopted to treat waste lithium-containing cathode active materials under normal pressure and low temperature conditions. By combining the Fe7S8 source with the alkaline solution, lithium was extracted efficiently and the loss of transition metals was reduced.
Excellent pre-lithiation effect was achieved at normal pressure and low temperature, reducing the loss of transition metals and improving the purity and selectivity of lithium recovery.
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Figure CN117737438B_ABST
Abstract
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, such as the common lithium-ion batteries, are widely used in secondary energy storage applications in consumer electronics, electric vehicles, and power grid systems due to their high energy density, high power density, long lifespan, and compact size. Because of the widespread use of lithium-ion batteries in electronic devices, electric vehicles, and energy storage, the recycling rate of metals from spent lithium-ion batteries is very fast. From the perspective of resource utilization and environmental protection, this recycling method aligns with the requirements of sustainable development.
[0003] For waste materials, existing technologies mainly focus on a single-stage leaching of all elements (such as the common acid leaching). While this process is simple to operate, the efficiency of single-stage leaching of metals still needs improvement, and the process can easily lead to the loss of strategic resource lithium. Therefore, existing technologies have also developed some processes for recovering other elements after pre-extracting lithium. For example, Chinese patent document CN114956130A discloses a subcritical pre-extraction method for waste lithium battery cathode materials. This method involves heating a mixed solution containing waste lithium battery cathode powder, water, and a polyhydroxy alcohol to bring the water to a subcritical state. Maintaining this subcritical state, pre-extraction of lithium is performed. After processing, solid-liquid separation is performed to obtain the lithium extraction solution. The polyhydroxy alcohol is one or more of ethylene glycol or propylene glycol. The volume fraction of the polyhydroxy alcohol in the water and polyhydroxy alcohol is 30-95%. The temperature of the subcritical stage is 180℃-220℃. For example, Chinese patent document CN113862476A discloses a method for pre-extracting lithium from waste lithium-ion batteries, including: Step 1: Pre-treating the waste lithium-ion batteries to obtain electrode active material powder; Step 2: Alkaline washing of the electrode active material powder with an alkaline solution, filtering to remove copper and aluminum, and drying the alkaline-washed electrode active material powder; Step 3: Loading the dried electrode active material powder and transition metal salt solution into a high-pressure reactor at a certain solid-liquid ratio for hydrothermal reaction; Step 4: Taking out the solution after hydrothermal reaction, filtering to obtain lithium-rich leachate and transition metal oxide leachate residue; Step 5: After purifying and removing impurities from the lithium-rich leachate, adding carbonate or bicarbonate to precipitate lithium to obtain lithium carbonate. For example, Chinese patent document CN117004823A discloses a method for preferentially extracting lithium manganese from waste LNCM materials. The method is characterized by filling and sealing a raw material solution containing waste LNCM materials and alkali in a pressure-resistant container chamber, heating it to a temperature T, then introducing an oxygen-containing atmosphere to increase the pressure to P, and maintaining the temperature and pressure for leaching treatment; subsequently, depressurizing and cooling, and separating the solid and liquid to obtain a leaching solution enriched with lithium manganese and a leaching residue enriched with nickel and cobalt; the pressure P in the leaching treatment stage is 1.1 to 5 times the system pressure in the initial pressurization stage, and the temperature T is 200 to 350°C.
[0004] In summary, although existing technologies offer many pre-lithiation processes, most of them require high temperature conditions. The pre-lithiation effect under normal pressure needs to be improved. Moreover, it can easily lead to the loss of other transition metals in the cathode material. Summary of the Invention
[0005] To address the problems faced in the recycling of existing waste lithium-ion battery cathodes, the present invention aims to provide a Fe7S8-assisted alkaline leaching method for lithium extraction from waste lithium-containing cathode active materials, which aims to improve the pre-extraction effect under normal pressure and reduce the accompanying loss of transition metal elements.
[0006] The second objective of this invention is to provide a method for recycling waste lithium-containing cathode active materials.
[0007] The third objective of this invention is to provide a method for regenerating waste lithium-containing cathode active materials.
[0008] A Fe7S8-assisted alkaline leaching method for lithium extraction from waste lithium-containing cathode active materials involves subjecting the material to be treated, which contains waste lithium-containing cathode active materials, to alkaline leaching treatment with the assistance of an Fe7S8 source to obtain a lithium-rich leachate.
[0009] To address the problems of difficulty in deeply removing lithium from the lattice of waste lithium-containing cathode active materials and unsatisfactory removal selectivity, this invention innovatively demonstrates that the innovative use of Fe7S8-assisted alkaline leaching lithium extraction treatment can achieve excellent pre-lithiation results under normal pressure and relatively low temperature conditions. Furthermore, it can avoid the loss of other elements and exhibit excellent pre-lithiation selectivity.
[0010] In this invention, the waste lithium-containing positive electrode active material can be obtained from waste lithium-ion batteries using known processes.
[0011] The technical solution of this invention has good versatility and can be applied to the preferential lithium extraction of any active material. For example, as an optional method, the lithium-containing cathode active material can be at least one of lithium-containing phosphates or oxidizing salts containing at least one element selected from iron, nickel, cobalt, and manganese; further, it can be at least one of lithium iron phosphate, lithium manganese phosphate, lithium iron manganese phosphate, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, or nickel-cobalt-manganese ternary materials.
[0012] In this invention, the requirements for the type of raw materials in the material to be treated are relatively lenient. For example, the material to be treated may also contain at least one of the following: binder, conductive agent, negative electrode active material, separator, current collector, and electrolyte.
[0013] In this invention, there are no special requirements for the content of waste lithium-containing positive electrode active material in the material to be treated. Considering the economic efficiency of the process, the content of the waste lithium-containing positive electrode active material is preferably above 50 wt.%, more preferably above 80 wt.%, and even more preferably 80-95 wt.%.
[0014] The present invention demonstrates that the Fe7S8 active component in the Fe7S8 source is key to improving the effect of alkaline leaching under normal pressure.
[0015] In the Fe7S8 source described in this invention, the content of Fe7S8 active ingredient is above 85 wt.%, and more preferably above 95 wt.%.
[0016] In this invention, the Fe7S8 source is obtained by calcining an FeS2 source at a temperature of 500–900°C for 10–60 min. Research in this invention shows that, through the aforementioned method, combined with the controlled temperature and time, a Fe7S8 product with high phase purity can be unexpectedly obtained, thereby contributing to improved auxiliary atmospheric pressure alkalinity.
[0017] In this invention, the atmosphere during the calcination process is a protective atmosphere;
[0018] In this invention, the calcination temperature can be 550–750°C.
[0019] In this invention, the heat preservation and calcination time is 15 to 50 minutes, and more preferably 30 to 45 minutes.
[0020] In this invention, the weight ratio of the waste lithium-containing positive electrode active material in the material to be treated to the Fe7S8 in the Fe7S8 source is 1:1 to 10, and can be further 1:2 to 5.
[0021] In this invention, the alkaline solute in the alkaline solution during the alkaline leaching lithium extraction process includes at least one of sodium hydroxide, potassium hydroxide, and ammonia water.
[0022] The concentration of alkaline solute in the alkaline solution can be adjusted routinely as needed. Considering the processing technology and ease of operation, it can be 1 to 3 M.
[0023] In this invention, the alkaline leaching lithium extraction process is carried out under normal pressure;
[0024] In this invention, the temperature of the alkaline leaching lithium extraction stage is 40–80°C, and more specifically 45–65°C;
[0025] In this invention, the liquid-to-solid ratio in the alkaline leaching lithium extraction stage can be conventionally adjusted as needed. Considering the simplicity of the process, it can be further set to 10-50 mL / g, and even further set to 20-40 mL / g.
[0026] In this invention, the time for the alkaline leaching lithium extraction stage is more than 0.5 hours, and can be further 1 to 4 hours, or even more specifically 1.5 to 2.5 hours.
[0027] This invention also provides a method for recovering elements from waste lithium-containing cathode active materials. The method described in this invention is used to perform alkaline leaching to extract lithium, thereby obtaining a lithium-rich leachate and a leaching residue enriched with transition metals from the lithium-containing cathode active material. The leaching residue is then subjected to acid leaching to obtain a transition metal leachate.
[0028] The process of this invention can recover lithium from lithium-rich extracts and recover transition metals from transition metal leachates, based on known processes.
[0029] For example, in an optional embodiment of the present invention, lithium-rich leachate can be subjected to lithium precipitation treatment to obtain a lithium source;
[0030] In this invention, the acid leaching process can be conventional, with the aim of ensuring the effective leaching of metal elements from the active materials.
[0031] In this invention, the required precursor material can be obtained from the leachate based on known processes. For example, one optional approach is to adjust the pH of the transition metal leachate to 4-5, perform impurity removal treatment, and then perform co-precipitation treatment after adjusting the element ratio to obtain the transition metal precursor.
[0032] The present invention also provides a method for regenerating waste lithium-containing cathode active materials. The method of the present invention obtains a lithium source and a transition metal precursor, which are then mixed and calcined to obtain the regenerated active material.
[0033] Beneficial effects
[0034] This invention innovatively demonstrates that the innovative use of Fe7S8-assisted alkaline leaching for lithium extraction can achieve excellent pre-lithiation results under normal pressure and relatively low temperature conditions. Furthermore, it can avoid the loss of other elements and exhibit excellent pre-lithiation selectivity. Attached Figure Description
[0035] Figure 1 XRD patterns of Fe7S8 products before and after calcination of FeS2 in Example 1; Detailed Implementation
[0036] 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.
[0037] In this invention, the waste positive electrode active material containing the waste positive electrode active material can be obtained by stripping based on known processes. For example, as an optional method, the stripping steps are as follows: waste lithium-ion batteries (such as ternary batteries, lithium cobalt oxide batteries, etc.) are placed in 1-3 mol / L salt water for 25-35 hours of discharge treatment, the discharged batteries are dried at 80-90°C, the positive electrode and negative electrode are disassembled and separated, the positive electrode is immersed in N-methylpyrrolidone, the current collector in the electrode is separated, and the waste positive electrode powder (the waste positive electrode active material) is obtained by filtering, washing and drying.
[0038] In this invention, the material to be processed, in addition to containing waste positive electrode active material, is also permitted to contain conductive agents, binders, and other components. In this invention, there are no special requirements for the content of active material in the waste lithium-ion battery positive electrode material; however, considering the economics of the process, its content is preferably above 50 wt.%. In the following examples, unless otherwise stated, its active content is 85–90 wt.%.
[0039] In the following examples, the Fe7S8 can be an analytically pure raw material, and the presence of other iron sulfides and other components that do not interfere with the treatment is also permissible. In this invention, to better illustrate the auxiliary effect of Fe7S8 on alkaline leaching, the following examples all use raw materials with a content of 95 wt% or higher for experiments. These can be commercially available products or obtained by holding analytically derived FeS2 at a temperature of Ar and T for a duration of t, where T is 500–900°C and t is 10–60 min, or more specifically 35–45 min.
[0040] Example 1
[0041] Step (1):
[0042] The positive electrode powder stripped from waste nickel-cobalt-manganese ternary batteries (NCM 1:1:1 batteries) and Fe7S8 (obtained by heating FeS2 at 550℃ for 40 min with Ar, with Fe7S8 content above 95wt.% and a weight ratio of positive electrode active material to Fe7S8 of 1:3) were placed in a 2M sodium hydroxide aqueous solution (liquid-solid ratio of 30ml / g, based on the positive electrode powder) and leached at 45℃ under normal pressure for 2 h. Subsequently, solid-liquid separation was performed to obtain lithium-rich liquid and ternary oxide residue. The purity of Li in the lithium-rich liquid was 98%, the recovery rate was 98.9%, and the content of nickel, cobalt, and manganese ternary elements was less than 0.01ppm.
[0043] Li2CO3 is obtained by adding Na2CO3 to a lithium-rich solution and evaporating and crystallizing it.
[0044] Step (2): Other recycling and regeneration steps
[0045] The ternary oxide slag obtained in step 1 was subjected to sulfuric acid leaching to obtain a leachate. The pH was then adjusted to 4.5 for impurity removal and filtration. The molar ratio of nickel, cobalt, and manganese in the filtrate was adjusted to 1:1:1, and NaOH-NH3·H2O was added to adjust the pH to 11 to precipitate nickel, cobalt, and manganese, thus obtaining a nickel-cobalt-manganese precursor. The obtained nickel-cobalt-manganese precursor and the obtained Li2CO3 (Li excess coefficient of 1.03) were mixed evenly and annealed at 800℃ for 10 h to obtain the regenerated positive electrode active material.
[0046] The recycled positive electrode active material, conductive carbon black, and PVDF are mixed in a weight ratio of 8:1:1, slurried, and coated onto the positive electrode current collector. After drying, the positive electrode is obtained.
[0047] In a glove box, 1M LiPF6 was used as the electrolyte (EC:DEC:EMC = 1:1:1), and the separator was a Celgard 2400 polypropylene membrane. The above-mentioned positive electrode was used as the working electrode, and lithium was used as the counter electrode. The positive electrode exhibited a reversible capacity of 185 mAh / g at a 1C rate regeneration at room temperature.
[0048] Example 2
[0049] Compared with Example 1, the only difference is that the conditions for obtaining Fe7S8 are changed, specifically:
[0050] Group A: Fe7S8 was obtained by heating FeS2 in Ar at 750℃ for 15 min;
[0051] Group B: Fe7S8 was obtained by heating FeS2 in Ar at 650℃ for 35 minutes;
[0052] The operation and testing were performed according to the method in Example 1, and the results are as follows:
[0053] Group A: The purity of Li in the lithium-rich solution was 98.5%, the recovery rate was 99.1%, and the contents of nickel, cobalt and manganese were all less than 0.01 ppm; the regenerated cathode at 1C at room temperature exhibited a reversible capacity of 184 mAh / g.
[0054] Group B: The purity of Li in the lithium-rich solution was 98.6%, the recovery rate was 99.2%, and the contents of nickel, cobalt and manganese were all less than 0.01 ppm; the regenerated cathode at 1C at room temperature showed a reversible capacity of 187 mAh / g.
[0055] Example 3
[0056] Compared to Example 1, the only difference is that the weight ratio of the positive electrode active material and Fe7S8 in the positive electrode powder is changed, as follows:
[0057] Group A: The weight ratio of the positive electrode active material to Fe7S8 in the positive electrode powder is 1:2;
[0058] Group B: The weight ratio of the positive electrode active material to Fe7S8 in the positive electrode powder is 1:5;
[0059] The operation and testing were performed according to the method in Example 1, and the results are as follows:
[0060] Group A: The purity of Li in the lithium-rich solution was 97.3%, the recovery rate was 98.5%, and the contents of nickel, cobalt and manganese were all less than 0.03 ppm; the regenerated cathode at 1C at room temperature exhibited a reversible capacity of 175 mAh / g.
[0061] Group B: The purity of Li in the lithium-rich solution is 99.3%, the recovery rate is 99.3%, and the contents of nickel, cobalt and manganese are all less than 0.01 ppm; the regenerated cathode at 1C at room temperature exhibits a reversible capacity of 188 mAh / g.
[0062] Example 4
[0063] Compared to Example 1, the only difference is that the temperature and alkali concentration conditions of the leaching process were changed, and the experimental groups were as follows:
[0064] Group A: The leaching temperature was set to 60℃, and the leaching time was changed to 1.5h;
[0065] Group B: The alkali concentration was set to 3M, and the liquid-to-solid ratio during the leaching stage was 25mL / g;
[0066] The operation and testing were performed according to the method in Example 1, and the results are as follows:
[0067] Group A: The purity of Li in the lithium-rich solution was 98.3%, the recovery rate was 99.1%, and the contents of nickel, cobalt and manganese were all less than 0.01 ppm; the regenerated cathode at 1C at room temperature exhibited a reversible capacity of 188 mAh / g.
[0068] Group B: The purity of Li in the lithium-rich solution is 99.1%, the recovery rate is 99.4%, and the contents of nickel, cobalt and manganese are all less than 0.01 ppm; the regenerated cathode at 1C at room temperature exhibits a reversible capacity of 187 mAh / g.
[0069] Comparative Example 1
[0070] Compared with Example 1, the only difference is that Fe7S8 was not added; all other operations and parameters are the same as in Example 1.
[0071] The procedure and testing were performed according to the method in Example 1, and the result was that the Li extraction rate was only 1.3%.
[0072] Comparative Example 2
[0073] Compared with Example 1, the only difference is that the conditions for obtaining the Fe7S8 source are changed. The difference in step 1 is as follows:
[0074] The cathode powder and auxiliary materials stripped from waste nickel-cobalt-manganese ternary batteries (same as in Example 1) were placed in a 2M sodium hydroxide aqueous solution (liquid-solid ratio of 30 ml / g, based on the cathode material) and leached at 45°C under normal pressure for 2 hours. Subsequently, solid-liquid separation was performed to obtain lithium-rich liquid and ternary oxide residue. The Li extraction rate in the lithium-rich liquid was only 63.2%.
[0075] Comparative Example 3
[0076] Compared with Example 2, the only difference is that the heat preservation time t is set to 10 minutes. Other operations and parameters are the same as in Comparative Example 2.
[0077] The result was that the Li extraction rate in the lithium-rich solution was only 75.3%.
[0078] Comparative Example 4
[0079] Compared with Example 1, the only difference is that FeS2 is used instead of Fe7S8. That is, the amount of FeS2 is the same, but no heat preservation and calcination treatment is performed. All other operations and parameters are the same as in Example 1.
[0080] The result was that the Li extraction rate in the lithium-rich solution was only 42.9%.
Claims
1. A Fe7S8-assisted alkaline leaching method for lithium extraction from waste lithium-containing cathode active materials, characterized in that, The material to be treated, which contains waste lithium-containing positive electrode active material, is subjected to alkaline leaching for lithium extraction with the assistance of an Fe7S8 source to obtain a lithium-rich leachate. The content of Fe7S8 active ingredient is above 85wt.%; the Fe7S8 source is obtained by calcining FeS2 source at a temperature of 500~900℃ for 15~50min. The lithium extraction process is carried out under normal pressure; the temperature during the lithium extraction stage is 40~80℃.
2. The Fe7S8-assisted alkaline leaching method for lithium extraction from waste lithium-containing cathode active materials as described in claim 1, characterized in that, The lithium-containing positive electrode active material is a lithium-containing positive electrode active material obtained from waste lithium-ion batteries.
3. The Fe7S8-assisted alkaline leaching method for lithium extraction from waste lithium-containing cathode active materials as described in claim 2, characterized in that, The lithium-containing positive electrode active material is at least one of lithium phosphates or oxidizing salts containing at least one of the elements selected from iron, nickel, cobalt, and manganese.
4. The Fe7S8-assisted alkaline leaching method for lithium extraction from waste lithium-containing cathode active materials as described in claim 3, characterized in that, The lithium-containing positive electrode active material is at least one of lithium iron phosphate, lithium manganese phosphate, lithium iron manganese phosphate, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, and nickel-cobalt-manganese ternary materials.
5. The Fe7S8-assisted alkaline leaching method for lithium extraction from waste lithium-containing cathode active materials as described in claim 2, characterized in that, The material to be processed also includes at least one of the following: binder, conductive agent, negative electrode active material, separator, current collector, and electrolyte.
6. The Fe7S8-assisted alkaline leaching method for lithium extraction from waste lithium-containing cathode active materials as described in claim 5, characterized in that, The content of the waste lithium-containing positive electrode active material in the material to be processed is above 50 wt.%.
7. The Fe7S8-assisted alkaline leaching method for lithium extraction from waste lithium-containing cathode active materials as described in claim 1, characterized in that, The content of Fe7S8 active ingredient is above 95wt.%.
8. The Fe7S8-assisted alkaline leaching method for lithium extraction from waste lithium-containing cathode active materials as described in claim 1, characterized in that, The atmosphere during the calcination process is a protective atmosphere.
9. The Fe7S8-assisted alkaline leaching method for lithium extraction from waste lithium-containing cathode active materials as described in claim 1, characterized in that, The calcination time is 30-45 minutes.
10. The Fe7S8-assisted alkaline leaching method for lithium extraction from waste lithium-containing cathode active materials as described in claim 1, characterized in that, The calcination time is 40 minutes.
11. The Fe7S8-assisted alkaline leaching method for lithium extraction from waste lithium-containing cathode active materials as described in any one of claims 1 to 10, characterized in that, The weight ratio of the waste lithium-containing positive electrode active material in the material to be treated to the Fe7S8 in the Fe7S8 source is 1:1~10.
12. The Fe7S8-assisted alkaline leaching method for lithium extraction from waste lithium-containing cathode active materials as described in claim 11, characterized in that, The weight ratio of the waste lithium-containing positive electrode active material in the material to be treated to the Fe7S8 in the Fe7S8 source is 1:2~5.
13. The Fe7S8-assisted alkaline leaching method for lithium extraction from waste lithium-containing cathode active materials as described in any one of claims 1 to 10, characterized in that, The alkaline solute in the alkaline solution during the alkaline leaching process for lithium extraction includes at least one of sodium hydroxide, potassium hydroxide, and ammonia.
14. The Fe7S8-assisted alkaline leaching method for lithium extraction from waste lithium-containing cathode active materials as described in claim 13, characterized in that, The concentration of alkaline solute in the alkaline solution is 1~3M.
15. The Fe7S8-assisted alkaline leaching method for lithium extraction from waste lithium-containing cathode active materials as described in claim 1, characterized in that, The temperature for the alkaline leaching lithium extraction stage is 45~65℃.
16. The Fe7S8-assisted alkaline leaching method for lithium extraction from waste lithium-containing cathode active materials as described in claim 1, characterized in that, The liquid-to-solid ratio during the alkaline leaching lithium extraction stage is 10~50 mL / g.
17. The Fe7S8-assisted alkaline leaching method for lithium extraction from waste lithium-containing cathode active materials as described in claim 1, characterized in that, The liquid-to-solid ratio during the alkaline leaching lithium extraction stage is 20-40 mL / g.
18. The Fe7S8-assisted alkaline leaching method for lithium extraction from waste lithium-containing cathode active materials as described in claim 1, characterized in that, The time for the alkaline leaching lithium extraction stage is more than 0.5 hours.
19. The Fe7S8-assisted alkaline leaching method for lithium extraction from waste lithium-containing cathode active materials as described in claim 1, characterized in that, The time for the alkaline leaching lithium extraction stage is 1-4 hours.
20. A method for elemental recovery from waste lithium-containing cathode active materials, characterized in that, Alkaline leaching for lithium extraction is performed using the method described in any one of claims 1 to 19 to obtain a lithium-rich leachate and a leaching residue enriched with transition metals from lithium-containing cathode active materials. The leaching residue was subjected to acid leaching to obtain a transition metal leachate.
21. The method for elemental recovery from waste lithium-containing cathode active materials as described in claim 20, characterized in that, The lithium-rich leachate was subjected to lithium precipitation treatment to obtain a lithium source; The pH of the transition metal leaching solution was adjusted to 4-5 for impurity removal, followed by co-precipitation after adjusting the element ratio to obtain the transition metal precursor.
22. A method for regenerating waste lithium-containing cathode active materials, characterized in that, A lithium source and a transition metal precursor are obtained by means of any one of claims 20 to 21, and then mixed and calcined to obtain a regenerated active material.