Method for recycling and regenerating positive electrode material from lithium ion battery and modifying positive electrode material
By removing aluminum, calcining, leaching reaction and co-precipitation of oxalic acid positive electrode materials from waste lithium-ion battery positive electrode materials, high-nickel ternary positive electrode materials are prepared, which solves the problems of waste of resources and insufficient performance, and achieves high efficiency of lithium-ion batteries Recycling and performance improvements.
Patent Information
- Application Number
- CN202411238022.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-05
- Publication Date
- 2024-12-10
AI Technical Summary
The prior art is difficult to effectively recover and regenerate the cathode material in lithium-ion batteries, resulting in waste of resources and environmental pollution. At the same time, the high-nickel ternary cathode material has shortcomings in terms of circulation performance and rate performance.
By performing alkali removal of aluminum, calcination, leaching reaction, oxalic acid co-precipitation and doping modification treatment of the positive electrode material of the used lithium-ion battery, high-nickel ternary positive electrode material with excellent electrochemical properties is prepared, and the recycling of resources is achieved and performance improvement.
It realizes efficient recycling and regeneration of the positive electrode material of waste lithium-ion batteries, improves the structural stability and lithium-ion diffusion performance of the material, and significantly improves the energy density, cycle stability and rate performance of the battery.
Smart Images
Figure CN119108693A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of waste lithium-ion battery regeneration, and in particular to a method for recovering and regenerating positive electrode materials from lithium-ion batteries and a method for modifying the same. Background Art
[0002] With the development of electric vehicles, lithium-ion batteries have gradually become the focus as energy storage devices. The industry's demand for lithium-ion batteries continues to grow, but this has also brought a lot of problems in scrapping, recycling and reuse. If not handled properly, it will inevitably have a negative impact on the environment and resources. At the same time, the positive electrode of waste lithium-ion batteries is rich in important strategic raw materials, such as non-ferrous metals such as lithium, nickel, cobalt and manganese. The efficient and clean extraction of these precious metals from the waste cathode is of great significance to the sustainable development of the lithium-ion battery industry.
[0003] As the market and users' demands for the battery life and safety of lithium-ion batteries continue to increase, the energy density design of single cells is also getting higher and higher. As the energy source and carrier of batteries, lithium-ion battery cathode materials play an important role in improving their energy density. In particular, high-nickel ternary cathode materials have advantages such as high specific capacity and energy density, and have become the preferred cathode materials for high-energy-density batteries in current technology. However, increasing the nickel content in high-nickel ternary cathode materials will reduce the structural stability of the cathode materials, thereby adversely affecting their cycle performance and rate performance in lithium-ion batteries.
[0004] Therefore, based on the current status of recycling lithium-ion cathode materials in the existing technology, we can combine recycling with preparation, simplify the recycling process, reduce the production process of materials, and realize the recycling of resources. At the same time, in order to make lithium-ion batteries have high energy density, high rate performance and high cycle performance, it is necessary to improve the structural stability, conductivity and lithium ion diffusion performance of nickel-rich ternary cathode materials. Summary of the invention
[0005] In view of the above technical problems, the present invention provides a method for recovering and regenerating positive electrode materials from lithium-ion batteries and modifying them. The method is simple in process, short in process time, low in cost, and can effectively realize the recycling of ternary positive electrode materials. At the same time, a doped and modified high-nickel ternary positive electrode material for lithium-ion batteries and a preparation method thereof are provided, so that the obtained high-nickel ternary positive electrode material has better electrochemical properties.
[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:
[0007] (1) Discharge and disassemble the used lithium-ion batteries. Collect the positive electrode parts and cut them into pieces of similar size;
[0008] (2) Use alkali solution to remove aluminum. Specifically, the fragments are added to the alkali solution for alkali washing. The principle of aluminum removal is:
[0009]
[0010] (3) filtering, washing, and drying. The collected powder is calcined to obtain waste lithium ion positive electrode materials;
[0011] (4) adding the cathode material powder to the leaching solution, performing a leaching reaction in a reactor, and filtering to obtain a leaching solution rich in valuable metals;
[0012] (5) adjusting the content of transition metal elements in the leaching solution, and obtaining a precursor by co-precipitation with oxalic acid under water bath heating conditions;
[0013] (6) keeping the precursor solution obtained in step (5) warm and aging it for a period of time, filtering, washing and drying it to obtain a precursor powder;
[0014] (7) The precursor, tungsten source and lithium source are mixed and ground evenly, and then calcined twice to obtain the modified positive electrode material.
[0015] As a preferred embodiment, the cathode material of the waste lithium-ion battery is one or more of lithium cobalt oxide cathode material, lithium nickel oxide cathode material, and nickel cobalt manganese cathode material.
[0016] As a preferred embodiment, the alkaline solution in step (2) can be sodium hydroxide or potassium hydroxide.
[0017] As a preferred embodiment, the concentration of the alkaline solution in step (2) is 0.5-2.5 mol·L -1 .
[0018] As a preferred embodiment, the calcination temperature in step (3) is 500-700°C and the calcination time is 2-6h.
[0019] As a preferred embodiment, the leaching solution in step (4) is a mixture of sulfuric acid solution and oxalic acid solution. The sulfuric acid concentration is 1-3 mol·L -1 , oxalic acid concentration is 5-30g`L -1 .
[0020] As a preferred embodiment, the solid-to-liquid ratio in step (4) is 5-40 g·L -1 , the reaction temperature is 50-90℃, and the reaction time is 30-120min.
[0021] As a preferred embodiment, the molar ratio of the three elements of nickel, cobalt and manganese in the nickel-cobalt-manganese mixed salt solution after adjustment in step (5) is 9:0.5:0.5, and the total concentration of the salt solution is 2 mol·L -1 .
[0022] As a preferred solution, in step (5), saturated sodium oxalate or saturated ammonium oxalate solution can be used as the precipitant, and the precipitant is in excess of 5%-20%.
[0023] As a preferred embodiment, in step (5), the reaction system temperature is 50-70°C, and the stirring speed is 200-600 r·min -1 , react for 2-6h.
[0024] As a preferred embodiment, the insulation temperature in step (6) is 50-70°C and the insulation time is 1-4h.
[0025] As a preferred embodiment, the aging time in step (6) is 3-8 hours and the drying temperature is 60-100°C.
[0026] As a preferred solution, the lithium source in step (7) can be lithium hydroxide or lithium carbonate. The molar ratio of the precursor to the lithium source is 1:(1.01-1.05).
[0027] As a preferred embodiment, the ratio of the tungsten source in step (7) to the precursor is 0-10%.
[0028] As a preferred embodiment, the sintering method in step (7) is a two-stage sintering, the first stage sintering temperature is 500-600°C, and the heating rate is 2-6°C`min -1 The holding time is 2-8h, the second stage calcination temperature is 680-800℃, and the heating rate is 2-6℃`min -1 , the insulation time is 10-16h.
[0029] As a preferred embodiment, the sintering environment in step (7) is an oxygen-rich environment.
[0030] This technical solution can effectively recycle waste ternary lithium-ion positive electrode materials, avoiding resource waste and environmental pollution problems, and realizing closed-loop utilization of resources. Another object of the present invention is to provide an ion-doped and modified high-nickel ternary positive electrode material obtained by the above-mentioned recycling and re-preparation method, which is used as a positive electrode material for lithium-ion batteries. When the present invention dopes nanoscale WO3, due to the strong WO bond, it can stabilize the material structure, greatly inhibit the loss of lattice oxygen, and greatly increase the lithium ion diffusion coefficient. In Example 2, W 6+ The doped and modified nickel-rich cathode material NCM955 has a first discharge capacity of 210.95 mAh g at a current density of 0.2C in the voltage range of 2.8-4.3 V. -1 After 100 cycles at 0.5C current density, the output capacity is still as high as 161.24 mAh`g -1The capacity retention rate can reach 87.75%, and the discharge capacity can reach 102.67mAh·g at 5C current density. -1 The original NCM955 material without modification in Example 1 has a capacity of only 124.45 mAh g after 100 cycles at a current density of 0.5C. -1 The capacity retention rate is only 69.15%, and the discharge capacity at 5C current density is only 63.98 mAh g -1 In summary, the W prepared by the present invention 6+ The doped and modified nickel-rich cathode material NCM955 has excellent electrochemical properties. BRIEF DESCRIPTION OF THE DRAWINGS
[0031] Figure 1 This is a SEM photo of the undoped modified nickel-rich positive electrode material NCM955 prepared in Example 1;
[0032] Figure 2 This is a SEM photo of the W-doped high-nickel positive electrode material NCM955 prepared in Example 2;
[0033] Figure 3 Cyclic stability test diagram of a lithium half-cell composed of the positive electrode materials prepared in Example 1 and Example 2 at a voltage range of 2.8-4.3V and a current density of 0.5C DETAILED DESCRIPTION
[0034] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.
[0035] The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, methods and instruments used are conventional materials, reagents, methods and instruments in the art unless otherwise specified, and can be obtained through commercial channels by those skilled in the art.
[0036] Example 1
[0037] (1) Use 2 mol·L NCM lithium-ion waste batteries -1 The battery is then discharged in a potassium chloride solution and the positive electrode is separated from the battery.
[0038] (2) Take an appropriate amount of positive electrode sheet and add it to 2 mol·L -1 NaOH solution, filtered, washed, dried, and calcined at 650 ° C for 5 h to obtain the positive electrode material. The waste positive electrode material was leached with a mixed solution of sulfuric acid and oxalic acid, and the sulfuric acid concentration was 2.5 mol·L -1 , oxalic acid concentration is 20 g·L -1, solid-liquid ratio is 10 g·L -1 The reaction was carried out at 85°C for 100 min.
[0039] (3) Using ICP-OES to test the nickel, cobalt and manganese contents of the leachate in step (2). Subsequently, appropriate amounts of nickel sulfate, cobalt sulfate and manganese sulfate were added to the leachate to adjust the molar ratio of nickel:cobalt:manganese in the leachate to 9:0.5:0.5 and ensure that the total metal ion concentration was 2 mol·L -1 The saturated solution of (NH4)2C2O4 was used as the precipitant, with an excess of 10%. The temperature of the reaction system was controlled at 55°C and the stirring speed was 300 r·min. -1 . The reaction was continued for 3 hours, followed by 1 hour of heat preservation and 4 hours of aging. Then, it was filtered, washed and dried at 80°C for 12 hours. Finally, the precursor (Ni 0.9 Co 0.05 Mn 0.05 )C2O4·2H2O.
[0040] (4) The precursor obtained in step (3) and lithium hydroxide are mixed and ground evenly, and the molar ratio of the precursor to lithium hydroxide is 1:1.03. The mixed materials are transferred to a quartz boat and placed in a tube furnace for staged calcination. First, the temperature is raised to 500°C, then kept constant for 2 hours, and then raised to 720°C and kept warm for 12 hours. During this period, O2 is continuously introduced, and the heating rate is controlled at 5°C·min throughout the process. -1 Finally, the positive electrode material LiNi 0.9 Co 0.05 Mn 0.05 O2, denoted as NCM955.
[0041] (5) The positive electrode active material, acetylene black and PVDF were mixed in NMP solvent at a mass ratio of 8:1:1, and then coated on aluminum foil after being evenly mixed using a homogenizer. The mixture was dried in an oven at 80°C for 6 hours, rolled and cut into pieces. Then, a button-type lithium-ion battery was assembled in sequence, including positive and negative electrode shells, negative electrode metal lithium sheet, polypropylene separator and LiPF6 electrolyte (1 mol·L -1 , EC:EMC:DMC volume ratio is 1:1:1), the battery uses 2016 button cell, and the electrochemical performance test is carried out in the voltage range of 2.8-4.3V.
[0042] Example 2
[0043] (1) Use 2 mol·L NCM lithium-ion waste batteries -1 The battery is then discharged in a potassium chloride solution and the positive electrode is separated from the battery.
[0044] (2) Take an appropriate amount of positive electrode sheet and add it to 2 mol·L-1 NaOH solution, filtered, washed, dried, and calcined at 650 ° C for 5 h to obtain the positive electrode material. The waste positive electrode material was leached with a mixed solution of sulfuric acid and oxalic acid, and the sulfuric acid concentration was 2.5 mol·L -1 , oxalic acid concentration is 20 g·L -1 , solid-liquid ratio is 10 g·L -1 The reaction was carried out at 85°C for 100 min.
[0045] (3) Using ICP-OES to test the nickel, cobalt and manganese contents of the leachate in step (2). Subsequently, appropriate amounts of nickel sulfate, cobalt sulfate and manganese sulfate were added to the leachate to adjust the molar ratio of nickel:cobalt:manganese in the leachate to 9:0.5:0.5 and ensure that the total metal ion concentration was 2 mol·L -1 The saturated solution of (NH4)2C2O4 was used as the precipitant, with an excess of 10%. The temperature of the reaction system was controlled at 55°C and the stirring speed was 300 r·min. -1 . The reaction was continued for 3 hours, followed by 1 hour of heat preservation and 4 hours of aging. Then, it was filtered, washed and dried at 80°C for 12 hours. Finally, the precursor (Ni 0.9 Co 0.05 Mn 0.05 )C2O4·2H2O.
[0046] (4) Mix and grind a certain amount of nano-WO3 and lithium hydroxide obtained in step (3) to make them uniform. The molar ratio of the precursor to WO3 is 99:1, and the molar ratio of the total amount of the precursor and WO3 to lithium hydroxide is 1:1.03. The uniformly mixed materials are transferred to a quartz boat and placed in a tube furnace for staged calcination. First, the temperature is raised to 500°C, then kept constant for 2 hours, and then raised to 720°C for 12 hours. During this period, O2 is continuously introduced, and the heating rate is controlled at 5°C·min throughout the process. -1 The chemical formula of NCM955 doped with 1%W molar ratio is Li(Ni 0.9 Co 0.05 Mn 0.05 ) 0.99 W 0.01 O2.
[0047] (5) The positive electrode active material, acetylene black and PVDF were mixed in NMP solvent at a mass ratio of 8:1:1, and then coated on aluminum foil after being evenly mixed using a homogenizer. The mixture was dried in an oven at 80°C for 6 hours, rolled and cut into pieces. Then, a button-type lithium-ion battery was assembled in sequence, including positive and negative electrode shells, negative electrode metal lithium sheet, polypropylene separator and LiPF6 electrolyte (1 mol·L -1, EC:EMC:DMC volume ratio is 1:1:1), the battery uses 2016 button cell, and the electrochemical performance test is carried out in the voltage range of 2.8-4.3V.
[0048] Example 3
[0049] (1) Use 2 mol·L NCM lithium-ion waste batteries -1 The battery is then discharged in a potassium chloride solution and the positive electrode is separated from the battery.
[0050] (2) Take an appropriate amount of positive electrode sheet and add it to 2 mol·L -1 NaOH solution, filtered, washed, dried, and calcined at 650 ° C for 5 h to obtain the positive electrode material. The waste positive electrode material was leached with a mixed solution of sulfuric acid and oxalic acid, and the sulfuric acid concentration was 2.5 mol·L -1 , oxalic acid concentration is 20g`L -1 , solid-liquid ratio is 10 g·L -1 The reaction was carried out at 85°C for 100 min.
[0051] (3) Using ICP-OES to test the nickel, cobalt and manganese contents of the leachate in step (2). Subsequently, appropriate amounts of nickel sulfate, cobalt sulfate and manganese sulfate were added to the leachate to adjust the molar ratio of nickel:cobalt:manganese in the leachate to 9:0.5:0.5 and ensure that the total metal ion concentration was 2 mol·L -1 The saturated solution of (NH4)2C2O4 was used as the precipitant, with an excess of 10%. The temperature of the reaction system was controlled at 55°C and the stirring speed was 300 r·min. -1 . The reaction was continued for 3 hours, followed by 1 hour of heat preservation and 4 hours of aging. Then, it was filtered, washed and dried at 80°C for 12 hours. Finally, the precursor (Ni 0.9 Co 0.05 Mn 0.05 )C2O4·2H2O.
[0052] (4) Mix and grind a certain amount of nano-WO3 and lithium hydroxide obtained in step (3) to make them uniform. The molar ratio of the precursor to WO3 is 99:1, and the ratio of the total amount of the precursor and WO3 to lithium hydroxide is 1:1.05. The uniformly mixed materials are transferred to a quartz boat and placed in a tube furnace for staged calcination. First, heat to 500°C, then keep the temperature constant for 2h, and then heat to 750°C and keep the temperature for 12h. During this period, O2 is continuously introduced, and the heating rate is controlled at 5°C·min throughout the process. -1 .
[0053] (5) The positive electrode active material, acetylene black and PVDF were mixed in NMP solvent at a mass ratio of 8:1:1, and then coated on aluminum foil after being evenly mixed using a homogenizer. The mixture was dried in an oven at 80°C for 6 hours, rolled and cut into pieces. Then, a button-type lithium-ion battery was assembled in sequence, including positive and negative electrode shells, negative electrode metal lithium sheet, polypropylene separator and LiPF6 electrolyte (1 mol·L -1 , EC:EMC:DMC volume ratio is 1:1:1), the battery uses 2016 button cell, and the electrochemical performance test is carried out in the voltage range of 2.8-4.3V.
[0054] Example 4
[0055] (1) Use 2 mol·L NCM lithium-ion waste batteries -1 The battery is then discharged in a potassium chloride solution and the positive electrode is separated from the battery.
[0056] (2) Take an appropriate amount of positive electrode sheet and add it to 2 mol·L -1 NaOH solution, filtered, washed, dried, and calcined at 650 ° C for 5 h to obtain the positive electrode material. The waste positive electrode material was leached with a mixed solution of sulfuric acid and oxalic acid, and the sulfuric acid concentration was 2.5 mol·L -1 , oxalic acid concentration is 20 g·L -1 , solid-liquid ratio is 10 g·L -1 The reaction was carried out at 85°C for 100 min.
[0057] (3) Using ICP-OES to test the nickel, cobalt and manganese contents of the leachate in step (2). Subsequently, appropriate amounts of nickel sulfate, cobalt sulfate and manganese sulfate were added to the leachate to adjust the molar ratio of nickel:cobalt:manganese in the leachate to 9:0.5:0.5 and ensure that the total metal ion concentration was 2 mol·L -1 The saturated solution of (NH4)2C2O4 was used as the precipitant, with an excess of 10%. The temperature of the reaction system was controlled at 55°C and the stirring speed was 300 r·min. -1 . The reaction was continued for 3 hours, followed by 1 hour of heat preservation and 4 hours of aging. Then, it was filtered, washed and dried at 80°C for 12 hours. Finally, the precursor (Ni 0.9 Co 0.05 Mn 0.05 )C2O4·2H2O.
[0058] (4) Mix and grind a certain amount of nano-WO3 and lithium hydroxide obtained in step (3) to make them uniform. The molar ratio of the precursor to WO3 is 99:1, and the ratio of the total amount of the precursor and WO3 to lithium hydroxide is 1:1.03. The uniformly mixed materials are transferred to a quartz boat and placed in a tube furnace for staged calcination. First, the temperature is raised to 550°C, then kept constant for 2 hours, and then raised to 720°C for 16 hours. O2 is continuously introduced during this period, and the heating rate is controlled at 5°C·min throughout the process. -1 .
[0059] (5) The positive electrode active material, acetylene black and PVDF were mixed in NMP solvent at a mass ratio of 8:1:1, and then coated on aluminum foil after being evenly mixed using a homogenizer. The mixture was dried in an oven at 80°C for 6 hours, rolled and cut into pieces. Then, a button-type lithium-ion battery was assembled in sequence, including positive and negative electrode shells, negative electrode metal lithium sheet, polypropylene separator and LiPF6 electrolyte (1 mol·L -1 , EC:EMC:DMC volume ratio is 1:1:1), the battery uses 2016 button cell, and the electrochemical performance test is carried out in the voltage range of 2.8-4.3V.
Claims
1. A method for recovering and regenerating positive electrode materials and modifying them from lithium-ion batteries, characterized in that: The following steps are involved: (1) Discharge and disassemble the used lithium-ion batteries. Collect the positive electrode parts and cut them into positive electrode sheets of similar size; (2) adding the positive electrode sheets to an alkaline solution for alkaline leaching and using the alkaline solution to remove aluminum; (3) filtering, washing, and drying. The collected powder is calcined to obtain waste lithium-ion positive electrode materials; (4) adding the cathode material powder to the leaching solution, performing a leaching reaction in a reactor, and filtering to obtain a leaching solution rich in valuable metals; (5) adjusting the content of transition metal elements in the leaching solution, and obtaining a precursor by co-precipitation with oxalic acid under water bath heating conditions; (6) keeping the precursor solution obtained in step (5) warm for a period of time, filtering, washing, and drying to obtain a precursor powder; (7) The precursor, tungsten source and lithium source are mixed and ground evenly, and then calcined twice to obtain the modified positive electrode material.
2. A method for recovering and regenerating positive electrode materials and modifying them from lithium-ion batteries as claimed in claim 1, characterized in that: The waste lithium-ion battery positive electrode material in step (1) is one or more of a lithium cobalt oxide positive electrode material, a lithium nickel oxide positive electrode material, and a nickel cobalt manganese positive electrode material.
3. A method for recovering and regenerating positive electrode materials and modifying them from lithium-ion batteries as claimed in claim 1, characterized in that: The alkaline solution in step (2) can be sodium hydroxide or potassium hydroxide. The concentration of the alkaline solution is 0.5-2.5 mol•L -1 .
4. A method for recovering and regenerating positive electrode materials and modifying them from lithium-ion batteries as claimed in claim 1, characterized in that: In step (3), the calcination temperature is 500-700°C and the calcination time is 2-6 h.
5. A method for recovering and regenerating positive electrode materials and modifying them from lithium-ion batteries as claimed in claim 1, characterized in that: The leaching solution in step (4) is a mixture of sulfuric acid solution and oxalic acid solution. The sulfuric acid concentration is 1-3 mol•L -1 , oxalic acid concentration is 5-30 g•L -1 , solid-liquid ratio is 5-40 g•L -1 , the reaction temperature is 50-90 ℃, and the reaction time is 30-120min.
6. A method for recovering and regenerating positive electrode materials and modifying them from lithium-ion batteries as claimed in claim 1, characterized in that: The molar ratio of the three elements of nickel, cobalt and manganese in the nickel-cobalt-manganese mixed salt solution after adjustment in step (5) is 9:0.5:0.5, and the total concentration of the salt solution is 2 mol·L -1 . Use saturated sodium oxalate or saturated ammonium oxalate solution as the precipitant, and the precipitant is in excess of 5%-20%. The reaction system temperature is 50-70 ℃, and the stirring speed is 200-600 r•min -1 , react for 2-6 h.
7. A method for recovering and regenerating positive electrode materials and modifying them from lithium-ion batteries as claimed in claim 1, characterized in that: In step (6), the holding temperature is 50-70°C, the holding time is 1-4 h, the curing time is 3-8 h, and the drying temperature is 60-100°C.
8. A method for recovering and regenerating positive electrode materials and modifying them from lithium-ion batteries as claimed in claim 1, characterized in that: The lithium source in step (7) can be lithium hydroxide or lithium carbonate. The molar ratio of the precursor to the lithium source is 1:(1.01-1.05). The ratio of the tungsten source to the precursor is 0-10%. The sintering method is two-stage calcination, the first stage calcination temperature is 500-600 ℃, and the heating rate is 2-6 ℃•min -1 The holding time is 2-8 h, the second stage calcination temperature is 680-800 ℃, and the heating rate is 2-6 ℃•min -1 , the insulation time is 10-24 h.