A direct upgrade and recycling method based on waste nickel-rich layered cathode materials and its application

Abstract

This invention discloses a direct upgrading and recycling method and application based on waste nickel-rich layered cathode materials, belonging to the field of lithium-ion battery recycling technology for waste electric vehicles. A remediation environment is constructed using a LiOH-NaOH-KCl eutectic molten salt system. By measuring the metal mass fraction in the transition metal layer of the waste battery particles and determining the molar ratio of lithium to each transition metal element, the amount of lithium to be added is determined. High-temperature heating is used to repair structural defects in the cathode material, introduce dopant elements, and achieve single-crystal conversion, realizing a closed-loop direct upgrading and recycling of waste layered cathode materials. This invention, using the above method, effectively recovers elements such as lithium, nickel, and cobalt from the layered cathode materials of waste batteries while reducing recycling costs, and further upgrades and recycles them into single-crystal cathode materials. Batteries made from the single-crystal cathode materials recovered by this method have good electrical performance. The recycling method is simple and reasonable, with controllable costs and minimal waste, making it suitable for commercial production.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery recycling technology for used electric vehicles, and in particular to a direct upgrade and recycling method and application based on waste nickel-rich layered cathode material. Background Technology

[0002] With the rapid development of electrochemical energy storage technologies such as electric vehicles, the large number of retired lithium-ion batteries (LIBs) has made the issue of recycling increasingly urgent. Traditional metal recycling methods are energy-intensive and may cause environmental pollution.

[0003] Direct recycling technology, by repairing and reusing the inherent properties of battery cathode materials, can achieve more environmentally friendly and efficient battery material recycling. However, with the rapid increase in battery performance requirements, pyrometallurgy struggles to effectively separate some metal elements from battery materials. Hydrometallurgy is highly corrosive to equipment, has slow reaction rates, and a lengthy process. Direct recycling can no longer meet the requirements of high energy and high power density.

[0004] Therefore, it is of great significance to develop a simple, reasonable, cost-controllable, highly sensitive, and low-waste lithium recovery method to address the shortcomings of existing technologies. Summary of the Invention

[0005] The purpose of this invention is to provide a method and application for the direct upgrading and recycling of waste nickel-rich layered cathode materials. By constructing a molten salt system for environmental remediation, this method effectively recovers elements such as lithium, nickel, and cobalt from waste battery layered cathode materials while reducing recycling costs, and further upgrades and recycles them into single-crystal cathode materials. Batteries made from the single-crystal cathode materials recovered by this technology have good electrical performance, and the recycling method is simple, reasonable, cost-controllable, and waste-free, making it suitable for commercial production.

[0006] To achieve the above objectives, this invention provides a direct upgrade and recycling method based on waste nickel-rich layered cathode materials. The method involves crushing waste battery particles and constructing a repair environment using a LiOH-NaOH-KCl eutectic molten salt system. The amount of lithium to be added is determined by measuring the mass fraction of metals in the transition metal layer and the molar ratio of lithium to each transition metal element in the transition metal layer. Subsequently, high-temperature heating is used to simultaneously repair structural defects in the cathode material, introduce doping elements, and achieve single-crystal conversion, thus realizing a closed-loop direct upgrade and recycling of waste layered cathode materials.

[0007] Preferably, it includes the following steps:

[0008] (1) Disassemble the waste battery to obtain the waste battery positive electrode material and crush it with a high-energy ball mill to obtain waste positive electrode material particles;

[0009] (2) The waste cathode material particles are mixed with hot alkaline solution and added to the reactor and heated and stirred continuously to decompose the polyvinylidene fluoride in the waste cathode material particles and remove the electrolyte to obtain layered metal hydroxide.

[0010] (3) Grind the obtained layered metal hydroxide with waste cathode material particles to obtain a powder mixture, and wash and dry the powder mixture;

[0011] (4) Take the powder mixture and perform EDTA chemical titration to determine the metal mass fraction of the transition metal layer in the powder mixture. After dissolving the powder mixture in aqua regia, perform ICP detection to determine the molar ratio of lithium element to each transition metal element in the transition metal layer in the powder mixture.

[0012] (5) Mix NaOH-LiOH-KCl solutions according to the molar ratio to construct a molten salt system to repair the environment, and add the layered metal hydroxide obtained in step (3) and heat.

[0013] (6) When heating to an appropriate temperature, add lithium source and dopant to the system and continue heating until no more single crystal material with smooth surface is produced, and the shape is regular and uniform.

[0014] Preferably, the particle size of the waste cathode material particles in step (1) is 2-3 μm.

[0015] Preferably, the hot alkaline solution in step (2) is a sodium hydroxide solution with a concentration of 0.5N, where N is the molar amount of metal elements in the waste cathode material particles, the heating temperature of the reactor is 100-150℃, and the stirring and heating time is 2-12 h.

[0016] Preferably, in step (3), the powder mixture is washed with deionized water and vacuum dried at a temperature of 120-140°C.

[0017] Preferably, the transition metal elements in the transition metal layer in step (4) are nickel, cobalt and manganese.

[0018] Preferably, in step (5), the molar ratio of NaOH, LiOH and KCl in the NaOH-LiOH-KCl solution is 2:1:2.

[0019] Preferably, in step (6), when the heating temperature reaches 420-750℃, the mass fraction of lithium source and dopant added to the transition metal layer is 50-60%, the remaining molar content of lithium ions is 0.75-0.85, and the heating continues to 850℃. The lithium source is lithium hydroxide monohydrate, and the dopant is Al-ZrO2 powder.

[0020] This invention also provides an application of the above-mentioned direct upgrade and recycling method based on waste nickel-rich layered cathode materials, which is applied to recycled lithium-ion battery cathode materials.

[0021] Preferably, it is applied to degraded layered materials, transforming the degraded layered materials into high-voltage durable cathode materials.

[0022] Therefore, the present invention employs the above-mentioned method and application for direct upgrading and recycling of waste nickel-rich layered cathode materials, which has the following beneficial effects:

[0023] 1. This invention involves adding aluminum and zirconium dopants to waste positive and negative electrode materials, which reduces pollution while ensuring that the single-crystal positive electrode material has good electrical performance under high voltage.

[0024] 2. This method uses the construction of a molten salt environment to ensure that single crystal materials have a good repair process.

[0025] 3. This method is simple to operate, has controllable costs, minimizes the waste of elements such as nickel, cobalt, and manganese, and reduces potential metal pollution, making it commercially valuable.

[0026] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the recycling process of this method;

[0028] Figure 2 This is an SEM image of a sample prepared using a direct upgrade and recycling method based on waste nickel-rich layered cathode material in Example 1 of this method.

[0029] Figure 3 This is the XRD pattern of a sample prepared using a direct upgrade and recycling method based on waste nickel-rich layered cathode material in Example 1 of this method.

[0030] Figure 4 This is the first charge-discharge curve of the sample prepared by the direct upgrade and recycling method based on waste nickel-rich layered cathode material in Example 1 of this method, and the first charge-discharge curve of the NCM lithium element recovery sample prepared by the pyrometallurgical method in Comparative Example 1.

[0031] Figure 5 This is a comparison chart of the application of a sample prepared using a direct upgrade and recycling method based on waste nickel-rich layered cathode material, as described in Example 1. Detailed Implementation

[0032] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0033] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0034] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. These other embodiments are also covered within the scope of protection of this invention.

[0035] As per the instruction manual Figure 1 As shown, this invention discloses a direct upgrading and recycling method based on waste nickel-rich layered cathode materials. The method involves crushing waste cathode material particles, constructing a repair environment using a LiOH-NaOH-KCl eutectic molten salt system, determining the amount of lithium to be added by measuring the mass fraction of metals in the transition metal layer and the molar ratio of lithium to each transition metal element in the transition metal layer, and then simultaneously achieving structural defect repair, doping element introduction, and single crystallization conversion of the cathode material through high-temperature heating, thus realizing a closed-loop direct upgrading and recycling of waste layered cathode materials.

[0036] Includes the following steps:

[0037] (1) Disassemble the waste battery to obtain the waste battery positive electrode material and crush it with a high-energy ball mill to obtain waste positive electrode material particles;

[0038] (2) The waste cathode material particles are mixed with hot alkaline solution and added to the reactor and heated and stirred continuously to decompose the polyvinylidene fluoride in the waste cathode material particles and remove the electrolyte to obtain layered metal hydroxide.

[0039] (3) Grind the obtained layered metal hydroxide with waste cathode material particles to obtain a powder mixture, and wash and dry the powder mixture;

[0040] (4) Take the powder mixture and perform EDTA chemical titration to determine the metal mass fraction of the transition metal layer in the powder mixture. After dissolving the powder mixture in aqua regia, perform ICP detection to determine the molar ratio of lithium element to each transition metal element in the transition metal layer in the powder mixture.

[0041] (5) Mix NaOH-LiOH-KCl solutions according to the molar ratio to construct a molten salt system to repair the environment, and add the powder mixture obtained in step (3) and heat;

[0042] (6) When heating to an appropriate temperature, add lithium source and dopant to the system and continue heating until no more single crystal material with smooth surface is produced, and the shape is regular and uniform.

[0043] The particle size of the waste cathode material particles in step (1) is 2-3 μm.

[0044] The hot alkaline solution in step (2) is a sodium hydroxide solution with a concentration of 0.5N, where N is the molar amount of metal element in the waste positive electrode material particles. The heating temperature of the reactor is 100-150℃, and the stirring and heating time is 2-12h.

[0045] In step (3), the powder mixture is washed with deionized water and vacuum dried at a temperature of 120-140℃.

[0046] In step (4), the transition metal elements in the transition metal layer are nickel, cobalt, and manganese.

[0047] In step (5), the molar ratio of NaOH, LiOH, and KCl in the NaOH-LiOH-KCl solution is 2:1:2.

[0048] In step (6), when the heating temperature reaches 420-750℃, lithium source and dopant are added until the mass fraction of the transition metal layer is 50-60% and the remaining molar content of lithium ions is 0.75-0.85. The temperature is then further increased to 850℃. The lithium source is lithium hydroxide monohydrate and the dopant is Al-ZrO2 powder.

[0049] This invention also provides an application of the above-mentioned direct upgrading and recycling method based on waste nickel-rich layered cathode materials, applied to recycled lithium-ion battery cathode materials. This transforms degraded layered materials into high-voltage, durable cathode materials.

[0050] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention should be considered equivalent substitutions and are included within the protection scope of the present invention. Furthermore, it should be understood that after reading the content of this invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims and are all within the protection scope of the present invention.

[0051] Unless otherwise defined, the technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the use of related terms herein is merely for the purpose of describing particular embodiments and is not intended to limit this application.

[0052] Unless otherwise specified, the reagents, instruments, and equipment used in this invention are all commonly used by those skilled in the art.

[0053] Example 1 LiNi 0.83 Co 0.12 Mn 0.05 O2(SNCM83)

[0054] This embodiment proposes a method for environmental remediation by constructing a molten salt system, upgrading layered materials to single-crystal materials for recycling, including the following steps:

[0055] First, the waste batteries were disassembled to obtain 20g of waste battery positive electrode material, which was then crushed into 2μm particles using a high-energy ball mill.

[0056] Layered nickel-rich oxide (LO) particles were added to a reaction vessel and mixed with 5 M NaOH solution. The mixture was heated and stirred at 160 °C for 12 h to decompose PVDF and obtain layered metal hydroxide M(OH)2 (M is Ni, Co, or Mn).

[0057] Waste cathode material particles were ground with layered metal hydroxide to obtain a powder mixture. The resulting powder was washed with deionized water and dried under vacuum at 120°C.

[0058] The powder mixture was subjected to EDTA chemical titration, and the mass fraction of the TM layer was found to be 52%. Further acid dissolution with aqua regia and ICP detection were performed on the powder to determine the molar ratios of Li / Ni, Li / Co, and Li / Mn to be 0.81:0.83, 0.81:0.12, and 0.81:0.05, respectively.

[0059] Take 10 mL of 2 mol / L NaOH solution, 10 mL of 1 mol / L LiOH solution, and 10 mL of 2 mol / L KCl solution, mix them thoroughly, and construct a molten salt environment.

[0060] The powder mixture was added to a molten salt environment and heated. When the temperature reached 420°C, 13.7 g of lithium hydroxide monohydrate was added to the mixture. Heating was maintained, and during the heating process from 420°C to 750°C, 0.042 g of Al powder and 0.127 g of ZrO2 were gradually added. Heating continued until 850°C. No more smooth single-crystal material was produced, indicating the repair process was complete, and LiNi was obtained. 0.83 Co 0.12 Mn 0.05O2.

[0061] Figure 2 This is a SEM image of the sample prepared in this embodiment. As can be seen from the image, the repaired NCM cathode material has a good morphology and uniform grains.

[0062] Figure 3 This is the XRD pattern of the sample prepared in this embodiment. As can be seen from the figure, the NCM cathode material has a good layered structure.

[0063] Figure 5 This is a comparison chart of the cycle application of the sample prepared in this embodiment. As can be seen from the chart, the recovered battery material has a high energy retention rate.

[0064] Example 2 LiNi 0.85 Co 0.13 Mn 0.02 O2

[0065] This invention proposes a method for environmental remediation by constructing a molten salt system, upgrading layered materials into single-crystal materials for recycling, including the following steps:

[0066] First, the waste batteries were disassembled to obtain 20g of waste battery positive electrode material, which was then crushed into 2μm particles using a high-energy ball mill.

[0067] Layered nickel-rich oxide (LO) particles were added to a reaction vessel and mixed with 5 M NaOH solution. The mixture was heated and stirred at 160 °C for 12 h to decompose PVDF and obtain layered metal hydroxide M(OH)2 (M is Ni, Co, or Mn).

[0068] Waste cathode material particles and layered metal hydroxides were ground to obtain a powder mixture, which was then washed with deionized water and vacuum dried at 120°C.

[0069] The powder mixture was subjected to EDTA chemical titration, and the mass fraction of the TM layer was found to be 58%. Further acid dissolution with aqua regia and ICP detection were performed on the powder to determine the molar ratios of Li / Ni, Li / Co, and Li / Mn to be 0.79:0.85, 0.79:0.13, and 0.79:0.02, respectively.

[0070] Take 10 mL of 2 mol / L NaOH solution, 10 mL of 1 mol / L LiOH solution, and 10 mL of 2 mol / L KCl solution, mix them thoroughly, and construct a molten salt environment.

[0071] The powder mixture was added to a molten salt environment and heated. When the temperature reached 420°C, 13.9 g of lithium hydroxide monohydrate was added to the mixture. Heating was maintained, and during the heating process from 420°C to 750°C, 0.040 g of Al powder and 0.117 g of ZrO2 were gradually added. Heating was continued until 850°C, at which point no more smooth single-crystal material was produced, indicating the repair process was complete.

[0072] Example 3 LiNi 0.88 Co 0.11 Mn 0.01 O2

[0073] This invention proposes a method for environmental remediation by constructing a molten salt system, upgrading layered materials into single-crystal materials for recycling, including the following steps:

[0074] First, the waste batteries were disassembled to obtain 20g of waste battery positive electrode material, which was then crushed into 2μm particles using a high-energy ball mill.

[0075] Layered nickel-rich oxide (LO) particles were added to a reaction vessel and mixed with 5 M NaOH solution. The mixture was heated and stirred at 160 °C for 12 h to decompose PVDF and obtain layered metal hydroxide M(OH)2 (M is Ni, Co, or Mn).

[0076] Waste cathode material particles were ground with layered metal hydroxide to obtain a powder mixture. The powder was washed with deionized water and dried under vacuum at 120°C.

[0077] The powder mixture was subjected to EDTA chemical titration, and the mass fraction of the TM layer was found to be 59%. Further acid dissolution with aqua regia and ICP detection were performed on the powder to determine that the molar ratios of Li / Ni, Li / Co, and Li / Mn were 0.82:0.88, 0.82:0.11, and 0.82:0.01, respectively.

[0078] Take 10 mL of 2 mol / L NaOH solution, 10 mL of 1 mol / L LiOH solution, and 10 mL of 2 mol / L KCl solution, mix them thoroughly, and construct a molten salt environment.

[0079] The powder mixture was added to a molten salt environment and heated. When the temperature reached 420°C, 13.3 g of lithium hydroxide monohydrate was added to the mixture. Heating was maintained, and during the heating process from 420°C to 750°C, 0.041 g of Al powder and 0.116 g of ZrO2 were gradually added. Heating was continued until 850°C, at which point no more smooth single-crystal material was produced, indicating the repair process was complete.

[0080] Comparative Example 1: Recovery of NCM Lithium Using Pyrometallurgical Method

[0081] Step 1: Mix pyrometallurgical slag, water and hydrochloric acid to obtain a mixed acid material. The mass ratio of slag:water:hydrochloric acid is 1:(0~2):(1~3), and the concentration of hydrochloric acid is 30wt%.

[0082] Step 2 involves subjecting the mixed acid material to a heat-preserving reaction at a temperature of 85°C for 4 hours, with the pH value at the final reaction endpoint controlled at 2.5.

[0083] Step 3: The reacted mixed acid material is vacuum dried at 300℃ to obtain aluminum-removed material;

[0084] Step 4: Soak the aluminum-removing material in water for 3 hours to obtain a leaching slurry;

[0085] Step 5 involves solid-liquid separation of the leaching slurry to obtain leaching liquid and solid A;

[0086] Step 6: Add lithium sulfate to the leaching solution, filter, and obtain lithium chloride conversion solution and solid B;

[0087] Step 7: Separate lithium chloride and other divalent ions from the lithium chloride conversion solution to obtain lithium chloride solution and divalent ion salt solution;

[0088] Step 8: Prepare lithium salt products from lithium chloride solution.

[0089] The obtained lithium salt product was used as a lithium source to prepare NCM cathode material.

[0090] The samples prepared in Example 1 and Comparative Example 1 were used in lithium-ion batteries as positive electrode materials, and their electrochemical performance was analyzed. The first charge-discharge curves of both are shown below. Figure 4 As shown: at 3.0-4.6V and 0.1C, the first discharge capacity of Example 1 is higher than that of Comparative Example 1, and the battery energy retention performance of Example 1 is better than that of Comparative Example 1.

[0091] Therefore, the present invention adopts the above-mentioned method and application for direct upgrading and recycling of waste nickel-rich layered cathode materials. While reducing recycling costs, it effectively recovers elements such as lithium, nickel, and cobalt from the layered cathode materials of waste batteries and further upgrades and recycles them into single-crystal cathode materials. The batteries made from the single-crystal cathode materials recovered by this method have good electrical performance. The recycling method is simple and reasonable, the cost is controllable, and there is less waste, making it suitable for commercial production.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for direct upgrading and recycling of waste nickel-rich layered cathode materials, characterized in that, By using crushed waste cathode material particles and constructing a remediation environment using a LiOH-NaOH-KCl eutectic molten salt system, the amount of lithium element to be added is determined by measuring the mass fraction of metals in the transition metal layer and the molar ratio of lithium element to each transition metal element in the transition metal layer. Subsequently, high-temperature heating is used to simultaneously achieve the repair of structural defects in the cathode material, the introduction of doping elements, and the single crystallization conversion, realizing the closed-loop direct upgrading and recycling of waste layered cathode materials. Includes the following steps: (1) Disassemble the waste battery to obtain the waste battery positive electrode material and crush it with a high-energy ball mill to obtain waste positive electrode material particles; (2) The waste cathode material particles are mixed with hot alkaline solution and added to the reactor and heated and stirred continuously to decompose the polyvinylidene fluoride in the waste cathode material particles and remove the electrolyte to obtain layered metal hydroxide. (3) Grind the obtained layered metal hydroxide with waste cathode material particles to obtain a powder mixture, and wash and dry the powder mixture; (4) Take the powder mixture and perform EDTA chemical titration to determine the metal mass fraction of the transition metal layer in the powder mixture. After dissolving the powder mixture in aqua regia, perform ICP detection to determine the molar ratio of lithium element to each transition metal element in the transition metal layer in the powder mixture. (5) Mix NaOH-LiOH-KCl solutions according to the molar ratio to construct a molten salt system to repair the environment, and add the powder mixture obtained in step (3) and heat; (6) When heating to an appropriate temperature, add lithium source and dopant to the system and continue heating until no more single crystal material with smooth surface is produced and the shape is regular and uniform; In step (6), when the heating temperature reaches 420-750℃, lithium source and dopant are added until the mass fraction of the transition metal layer is 50-60% and the remaining molar content of lithium ions is 0.75-0.

85. The temperature is then further increased to 850℃. The lithium source is lithium hydroxide monohydrate and the dopant is Al-ZrO2 powder.

2. The method for direct upgrading and recycling of waste nickel-rich layered cathode material according to claim 1, characterized in that, The particle size of the waste cathode material particles in step (1) is 2-3 μm.

3. The method for direct upgrading and recycling of waste nickel-rich layered cathode material according to claim 1, characterized in that, The hot alkaline solution in step (2) is a sodium hydroxide solution with a concentration of 0.5N, where N is the molar amount of metal element in the waste positive electrode material particles. The heating temperature of the reactor is 100-150℃, and the stirring and heating time is 2-12 h.

4. The method for direct upgrading and recycling of waste nickel-rich layered cathode material according to claim 1, characterized in that, In step (3), the powder mixture is washed with deionized water and vacuum dried at a temperature of 120-140℃.

5. The method for direct upgrading and recycling of waste nickel-rich layered cathode material according to claim 1, characterized in that, In step (4), the transition metal elements in the transition metal layer are nickel, cobalt, and manganese.

6. The method for direct upgrading and recycling of waste nickel-rich layered cathode material according to claim 1, characterized in that, In step (5), the molar ratio of NaOH, LiOH, and KCl in the NaOH-LiOH-KCl solution is 2:1:

2.

7. An application of the direct upgrading and recycling method based on waste nickel-rich layered cathode material as described in any one of claims 1-6, characterized in that, It is used in cathode materials for regenerated lithium-ion batteries.

8. The application of the direct upgrading and recycling method based on waste nickel-rich layered cathode material according to claim 7, characterized in that, It is applied to degraded layered materials, transforming them into high-voltage, durable cathode materials.

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