Method for preparing nickel-cobalt-manganese ternary precursor and lithium carbonate from waste lithium ion battery positive electrode powder

Abstract

This invention relates to the field of waste lithium-ion battery recycling, and discloses a short-process method for regenerating waste lithium-ion battery cathode powder to prepare nickel-cobalt-manganese ternary precursors and lithium carbonate. The method includes the following steps: (1) leaching waste lithium-ion battery cathode powder with a triacetic acid solution and a bicarbonate solution, obtaining leaching residue and leachate after leaching; (2) pyrolyzing the leachate obtained in step (1) and filtering it to obtain lithium carbonate precipitate and pyrolysis post-liquid; (3) co-precipitating the pyrolysis post-liquid with a sodium hydroxide solution to obtain the ternary precursor. This invention can achieve preferential lithium extraction, reduce lithium loss and its impact on co-precipitation during precursor production, reduce the nickel-cobalt-manganese separation and purification steps required in the original lithium extraction process, and improve lithium extraction efficiency.

Description

Technical Field

[0001] This invention belongs to the field of waste lithium-ion battery recycling, and specifically relates to a method for short-process regeneration of waste lithium-ion battery cathode powder to prepare nickel-cobalt-manganese ternary precursors and lithium carbonate. Background Technology

[0002] Used lithium-ion batteries contain large amounts of harmful heavy metals and organic chemicals, with metal elements such as nickel, cobalt, manganese, and lithium accounting for over 20% of their mass. To reduce the environmental impact of used lithium-ion batteries and address the scarcity of these metal resources, their recycling is urgently needed.

[0003] The recycling process for cathode materials from spent lithium-ion batteries has been extensively studied. Leaching methods based on inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid offer high leaching efficiency and stable processes, but the high cost of leaching agents, slow leaching process, and complex wastewater treatment significantly hinder their application. To improve leaching rates and simplify the process, researchers have proposed using nitrates, sulfates, and chlorides as roasting agents. High-temperature roasting followed by water leaching selectively extracts lithium, and then acid leaching recovers the remaining metal elements. The core of this recycling method is converting lithium into a soluble substance to separate it from the other elements, thereby shortening the recycling process. While these processes can achieve highly efficient and selective lithium extraction, metal ions in the roasting agent typically transfer to an insoluble solid phase, requiring additional treatment, which increases the difficulty of recycling and prolongs the process. Furthermore, all of these processes involve the use of ammonia, a pungent and volatile substance, which poses health risks to operators and harms the environment. Summary of the Invention

[0004] The purpose of this invention is to provide a short-process method for regenerating waste lithium-ion battery cathode powder to prepare nickel-cobalt-manganese ternary precursors and lithium carbonate. This method can achieve priority lithium extraction and the production process is environmentally friendly.

[0005] To achieve the objectives of this invention, the specific technical solution is as follows:

[0006] A method for short-process regeneration of waste lithium-ion battery cathode powder to prepare nickel-cobalt-manganese ternary precursors and lithium carbonate includes the following steps:

[0007] (1) The waste lithium-ion battery cathode powder is mixed with nitrogen-triacetic acid (NTA) solution and bicarbonate solution for leaching. After leaching, leaching residue and leaching solution are obtained.

[0008] (2) After pyrolyzing the leachate obtained in step (1), filter it to obtain lithium carbonate precipitate and pyrolysis liquid;

[0009] (3) The pyrolysis liquid obtained in step (2) is subjected to a coprecipitation reaction with sodium hydroxide solution to obtain a ternary precursor.

[0010] Further, in step (1), the concentration of the NTA solution is 1~10 mol / L; more preferably 3~8 mol / L.

[0011] Further, in step (1), the concentration of the bicarbonate solution is 1~3 mol / L; more preferably 1~2 mol / L.

[0012] Further, in step (1), the volume ratio of the NTA solution to the bicarbonate solution is 1:1 to 5:1; more preferably 2:1 to 5:1.

[0013] Further, in step (1), the leaching solid-liquid ratio of the positive electrode powder is 10~100 g / L; more preferably 20~50 g / L.

[0014] Furthermore, in step (1), the leaching temperature is 30~90℃; more preferably 50~80℃.

[0015] Further, in step (2), the temperature of the pyrolysis of the leachate is 50~100℃; more preferably 60~90℃.

[0016] Further, in step (3), the mass fraction of sodium hydroxide in the sodium hydroxide solution is 10-30%; more preferably 15-30%.

[0017] Furthermore, in step (3), during the coprecipitation reaction, the reaction pH is controlled to be 10-12; more preferably 11-12.

[0018] Furthermore, in step (3), the coprecipitation reaction time is 5~20h; more preferably 10~20h.

[0019] The beneficial effects of this invention are as follows:

[0020] (1) This invention creatively uses metal complexing agent NTA to replace ammonia water, which has an irritating odor and is volatile. The complexing order of NTA in the solution is nickel, cobalt, manganese, iron, and magnesium. Therefore, nickel, cobalt, and manganese are leached out during the leaching process, while impurity elements are present in the leaching residue. No additional impurity removal process is required, which shortens the recycling process of waste lithium-ion batteries. Secondly, during use, NTA is not volatile and has no irritating odor, which can greatly reduce the damage to the body and the environment during the production process.

[0021] (2) The combined use of NTA and bicarbonate in this invention allows lithium ions to form lithium bicarbonate in the solution, which can be obtained by pyrolysis to obtain lithium carbonate. This achieves priority lithium extraction, reduces lithium loss and the impact on co-precipitation during precursor production, reduces the nickel-cobalt-manganese separation and purification steps required in the original lithium extraction process, and improves lithium extraction efficiency. Attached Figure Description

[0022] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0023] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0024] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0025] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0026] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0027] Example 1

[0028] This embodiment provides a short-process method for regenerating spent lithium-ion battery cathode powder to prepare nickel-cobalt-manganese ternary precursors and lithium carbonate, such as... Figure 1 As shown, it includes the following steps:

[0029] (1) Place the waste lithium-ion batteries in saturated salt water and discharge them for 30 minutes. After the discharge is complete, dry the batteries in an oven, disassemble the battery casing to obtain the battery core, and then sort the positive and negative electrodes and the separator to obtain the positive electrode material. Calcinate the positive electrode material at 500 °C for 2 h in an argon atmosphere to obtain positive electrode powder, the composition of which is shown in Table 1.

[0030] Table 1

[0031] element Li Ni Co Mn Quality score, % 3.56 18.31 6.1 9.7

[0032] (2) 10.0 g of positive electrode powder was mixed with 400 ml of 3 mol / L NTA solution and 100 ml of 1 mol / L sodium bicarbonate solution for leaching. The leaching temperature was 80 ℃. After the reaction was completed, the solid and liquid were separated to obtain the leaching solution and the leaching residue.

[0033] (3) The leachate was pyrolyzed at 90 °C for 1 h. After solid-liquid separation, 1.872 g of lithium carbonate and the pyrolysis liquid were obtained. The purity of lithium carbonate was calculated to be 99.5% and the lithium recovery rate was 99.0%.

[0034] (4) Finally, the pyrolysis liquid and a 15% sodium hydroxide solution were subjected to a coprecipitation reaction. The pH during coprecipitation was 11 and the reaction time was 20 h. After the reaction was completed, the solid and liquid were separated to obtain 5.34 g of nickel-cobalt-manganese ternary precursor.

[0035] Example 2

[0036] This embodiment provides a short-process method for regenerating spent lithium-ion battery cathode powder to prepare nickel-cobalt-manganese ternary precursors and lithium carbonate, such as... Figure 1 As shown, it includes the following steps:

[0037] (1) Use the positive electrode powder from Example 1;

[0038] (2) 10.0 g of positive electrode powder was mixed with 300 ml of 5 mol / L NTA solution and 100 ml of 2 mol / L sodium bicarbonate solution for leaching. The leaching temperature was 60 ℃. After the reaction was completed, the solid and liquid were separated to obtain the leaching solution and the leaching residue.

[0039] (3) The leachate was pyrolyzed at 75 °C for 1 h. After solid-liquid separation, 1.878 g of lithium carbonate and the pyrolysis liquid were obtained. The purity of lithium carbonate was calculated to be 99.5% and the lithium recovery rate was 99.3%.

[0040] (4) Finally, the pyrolysis liquid and a 20% sodium hydroxide solution were coprecipitated. The pH during coprecipitation was 11.5 and the reaction time was 15 h. After the reaction was completed, the solid and liquid were separated to obtain 5.35 g of nickel-cobalt-manganese ternary precursor.

[0041] Example 3

[0042] This embodiment provides a short-process method for regenerating spent lithium-ion battery cathode powder to prepare nickel-cobalt-manganese ternary precursors and lithium carbonate, such as... Figure 1 As shown, it includes the following steps:

[0043] (1) Use the positive electrode powder from Example 1;

[0044] (2) 10.0 g of positive electrode powder was mixed with 200 ml of NTA solution with a concentration of 8 mol / L and 100 ml of sodium bicarbonate solution with a concentration of 1 mol / L for leaching. The leaching temperature was 50 ℃. After the reaction was completed, the solid and liquid were separated to obtain leaching solution and leaching residue.

[0045] (3) The leachate was pyrolyzed at 60 °C for 1 h. After solid-liquid separation, 1.878 g of lithium carbonate and the pyrolysis liquid were obtained. The purity of lithium carbonate was calculated to be 99.6% and the lithium recovery rate was 99.4%.

[0046] (4) Finally, the pyrolysis liquid and a 30% sodium hydroxide solution were coprecipitated. The pH during coprecipitation was 12 and the reaction time was 10 h. After the reaction was completed, the solid and liquid were separated to obtain 5.37 g of nickel-cobalt-manganese ternary precursor.

[0047] Comparative Example 1

[0048] This comparative example provides a short-process method for regenerating spent lithium-ion battery cathode powder to prepare nickel-cobalt-manganese ternary precursors and lithium carbonate, including the following steps:

[0049] (1) Use the positive electrode powder from Example 1;

[0050] (2) Mix 10.0 g of positive electrode powder and 3.5 g of ammonium sulfate and place them in a muffle furnace for two-stage high-temperature calcination. The first stage of calcination is carried out at 500 °C for 3 h, and the second stage of calcination is carried out at 700 °C for 3 h. After the reaction is completed, the calcined product is obtained.

[0051] (3) The calcined product was mixed with 1 L of pure water and leached for 1 h. After solid-liquid separation, lithium sulfate solution and nickel-cobalt-manganese alloy were obtained. Saturated sodium carbonate solution was added to lithium sulfate solution to obtain 1.86 g of lithium carbonate precipitate. The purity of lithium carbonate was calculated to be 98.8%, and the lithium recovery rate was 98%.

[0052] (4) The nickel-cobalt-manganese alloy was acidically leached with 2 mol / L dilute sulfuric acid at a solid-liquid ratio of 10 g / L for 8 h to obtain a sulfate solution.

[0053] (5) A 30% sodium hydroxide solution and concentrated ammonia were added to a sulfate solution for coprecipitation reaction. The pH during coprecipitation was 11 and the reaction time was 12 h, resulting in 5.31 g of nickel-cobalt-manganese ternary precursor.

[0054] Comparative Example 2

[0055] This comparative example provides a short-process method for regenerating spent lithium-ion battery cathode powder to prepare nickel-cobalt-manganese ternary precursors and lithium carbonate, including the following steps:

[0056] (1) Use the positive electrode powder from Example 1;

[0057] (2) 10.0 g of positive electrode powder was leached with 2 mol / L dilute sulfuric acid at a solid-liquid ratio of 10 g / L, and 5 ml of hydrogen peroxide was added as a reducing agent. After leaching, the solid and liquid were separated to obtain the leachate.

[0058] (3) Use a 30% sodium hydroxide solution to precipitate nickel, cobalt and manganese in the leachate as hydroxide precipitates to obtain nickel, cobalt and manganese hydroxide and lithium-containing solution;

[0059] (4) The lithium-containing solution was precipitated with sodium carbonate. After solid-liquid separation, 1.84 g of lithium carbonate precipitate was obtained. The purity of lithium carbonate was calculated to be 99%, and the lithium recovery rate was 97%.

[0060] (5) A 30% sodium hydroxide solution and concentrated ammonia were added to a sulfate solution for coprecipitation reaction. The pH during coprecipitation was 12 and the reaction time was 12 h, resulting in 5.34 g of nickel-cobalt-manganese ternary precursor.

[0061] Comparing the experimental results of Examples 1, 2, and 3 with those of Comparative Examples 1 and 2, the present invention simplifies the processing technology and improves the efficiency of lithium extraction and nickel-cobalt-manganese separation.

[0062] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of the present invention.

Claims

1. A method for short-process regeneration of spent lithium-ion battery cathode powder to prepare nickel-cobalt-manganese ternary precursors and lithium carbonate, characterized in that, Includes the following steps: (1) The waste lithium-ion battery cathode powder is mixed with a triacetic acid solution and a bicarbonate solution for leaching. After leaching, leaching residue and leaching solution are obtained. (2) After pyrolyzing the leachate obtained in step (1), filter it to obtain lithium carbonate precipitate and pyrolysis liquid; (3) The pyrolysis liquid obtained in step (2) is subjected to a coprecipitation reaction with sodium hydroxide solution to obtain a ternary precursor.

2. The method as described in claim 1, characterized in that, In step (1), the concentration of the hyponitrotriacetic acid solution is 1~10 mol / L.

3. The method as described in claim 1, characterized in that, In step (1), the bicarbonate solution is a sodium bicarbonate solution with a concentration of 1~3 mol / L.

4. The method as described in claim 3, characterized in that, In step (1), the volume ratio of the hyponitrotriacetic acid solution to the sodium bicarbonate solution is 1:1 to 5:

1.

5. The method as described in claim 1, characterized in that, In step (1), the leaching solid-liquid ratio of the positive electrode powder is 10~100g / L.

6. The method according to any one of claims 1-5, characterized in that, In step (1), the leaching temperature is 30~90℃.

7. The method according to any one of claims 1-5, characterized in that, In step (2), the pyrolysis temperature of the leachate is 50~100℃.

8. The method as described in claim 1, characterized in that, In step (3), the sodium hydroxide solution contains 10-30% sodium hydroxide by mass.

9. The method as described in claim 1, characterized in that, In step (3), the pH value of the coprecipitation reaction is controlled to be 10-12.

10. The method as described in claim 1, characterized in that, In step (3), the coprecipitation reaction takes 5 to 20 hours.

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