Direct upgrading and recycling method based on waste nickel-rich layered positive electrode material and application

Abstract

The invention discloses a direct upgrading and recycling method based on a waste nickel-rich layered positive electrode material and application, and belongs to the technical field of waste electric vehicle lithium ion battery recovery. A LiOH-NaCl-KCl eutectic molten salt system is used for constructing a repairing environment, and the lithium element supplementing amount is determined by measuring the mass fraction of metal in a waste battery particle transition metal layer and measuring the molar ratio of the lithium element to all transition metal elements; structural defect repair, doping element introduction and single crystallization conversion of the positive electrode material are achieved in a high-temperature heating mode, and closed-loop direct upgrading and recycling of the waste layered positive electrode material are achieved. By adopting the method, elements such as lithium, nickel and cobalt in the layered structure positive electrode material of the waste battery are effectively recovered while the recovery cost is reduced, the elements are further upgraded and recovered into the single crystal positive electrode material, the battery prepared from the single crystal positive electrode material recovered by the method is good in electrical performance, the recovery method is simple and reasonable, the cost is controllable, and the method is suitable for industrial production. Therefore, the method is suitable for commercial production.

Description

Technical Field

[0001] The invention relates to the technical field of recycling lithium-ion batteries of waste trams, and in particular to a direct upgrading and recycling method based on waste nickel-rich layered positive electrode materials and its application. Background Art

[0002] With the rapid development of electrochemical energy storage technologies such as electric vehicles, a large number of lithium-ion batteries (LIBs) have been retired, leading to an increasingly urgent recycling problem. Traditional metal recycling methods consume a lot of energy and may cause environmental pollution.

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

[0004] Therefore, in view of the shortcomings of the existing technology, it is of great significance to develop a simple, reasonable, cost-controlled, highly sensitive and less wasteful lithium recovery method. Summary of the invention

[0005] The purpose of the present invention is to provide a method and application of direct upgrading and recycling based on waste nickel-rich layered positive electrode materials. By constructing a method for repairing the environment with a molten salt system, while reducing the recycling cost, it can effectively recover lithium, nickel, cobalt and other elements in the layered positive electrode materials of waste batteries, and further upgrade and recycle them into single-crystal positive electrode materials. The battery prepared from the single-crystal positive electrode materials recycled by this technology has good electrical performance, and the recycling method is simple and reasonable, the cost is controllable, and the waste is small, which is suitable for commercial production.

[0006] To achieve the above-mentioned purpose, the present invention provides a direct upgrading and recycling method based on discarded nickel-rich layered positive electrode materials, which adopts crushed waste battery particles, and constructs a repair environment using a LiOH-NaCl-KCl eutectic molten salt system. The amount of lithium element supplementation is determined by measuring the metal mass fraction in the transition metal layer and the molar ratio of the lithium element to each transition metal element in the transition metal layer. Subsequently, high-temperature heating is used to simultaneously achieve structural defect repair, introduction of doping elements and single crystal conversion of the positive electrode material, thereby realizing closed-loop direct upgrading and recycling of waste layered positive electrode materials.

[0007] Preferably, the method comprises the following steps: (1) Disassembling waste batteries to obtain waste battery positive electrode materials and crushing them with a high-energy ball mill to obtain waste positive electrode material particles; (2) Mixing the waste cathode material particles with a hot alkaline solution, adding the mixture to a reactor, and continuously heating and stirring the mixture to decompose the polyvinylidene fluoride in the waste cathode material particles and remove the electrolyte to obtain a layered metal hydroxide; (3) grinding the obtained layered metal hydroxide and waste positive electrode material particles to obtain a powder mixture, and washing and drying the powder mixture; (4) taking the powder mixture and performing EDTA chemical titration to determine the metal mass fraction of the transition metal layer in the powder mixture, dissolving the powder mixture in aqua regia acid and performing ICP detection to determine the molar ratio of lithium element in the powder mixture to each transition metal element in the transition metal layer; (5) mixing NaOH-LiOH-KCl solutions according to a molar ratio to construct a molten salt system repair environment, adding the layered metal hydroxide obtained in step (2) and heating; (6) When heated to an appropriate temperature, lithium source and dopant are added to the system and heating is continued until a single crystal material with a smooth surface is no longer produced and the shape is regular and uniform.

[0008] Preferably, the particle size of the waste positive electrode material particles in step (1) is 2-3 μm.

[0009] Preferably, the hot alkaline solution in step (2) is a sodium hydroxide solution, the concentration of the sodium hydroxide solution is 0.5N, wherein N is the molar amount of the metal element in the waste positive electrode material particles, the heating temperature of the reactor is 100-150°C, and the stirring heating time is 2-12 h.

[0010] Preferably, in step (3), the powder mixture is washed with deionized water and vacuum dried at a temperature of 120-140°C.

[0011] Preferably, the transition metal elements of the transition metal layer in step (4) are nickel, cobalt and manganese.

[0012] Preferably, the molar ratio of NaOH, LiOH and KCl in the NaOH-LiOH-KCl solution in step (5) is 2:1:2.

[0013] Preferably, in step (6), when the heating temperature reaches 420-750°C, the lithium source and dopant are added to the transition metal layer with a mass fraction of 50-60%, and the residual molar content of lithium ions is 0.75-0.85, and the heating is continued to 850°C. The lithium source is lithium hydroxide monohydrate and the dopant is Al-ZrO2 powder.

[0014] The present invention also provides an application of the above-mentioned direct upgrading and recycling method based on waste nickel-rich layered positive electrode materials, which is applied to regenerating positive electrode materials for lithium-ion batteries.

[0015] Preferably, it is applied to degraded layered materials to convert the degraded layered materials into high-voltage and durable positive electrode materials.

[0016] Therefore, the present invention adopts the above-mentioned method and application of direct upgrading and recycling of waste nickel-rich layered positive electrode materials, which has the following beneficial effects: 1. The present invention adds aluminum and zirconium dopants to waste positive and negative electrode materials, thereby reducing pollution while ensuring that the single-crystal positive electrode material has good electrical properties under high voltage.

[0017] 2. This method uses a molten salt environment to ensure that the single crystal material has a good repair process.

[0018] 3. This method is simple to operate, cost-controlled, and has less waste of elements such as nickel, cobalt, and manganese. It also reduces potential metal pollution and has commercial application value.

[0019] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the recovery process of this method; Figure 2 This is a SEM image of a sample prepared by a direct upgrading and recycling method based on waste nickel-rich layered positive electrode materials in Example 1 of the present method; Figure 3 This is the XRD pattern of a sample prepared by a direct upgrading and recycling method based on waste nickel-rich layered positive electrode materials in Example 1 of the present method; Figure 4 The first cycle charge-discharge curves of the sample prepared by the method embodiment 1 using a direct upgrading and recycling method based on waste nickel-rich layered positive electrode materials and the sample recovered by the pyrometallurgical method for NCM lithium element in the comparative example 1; Figure 5 This is a cycle comparison diagram of the sample application prepared by a direct upgrading and recycling method based on waste nickel-rich layered positive electrode materials in Example 1 DETAILED DESCRIPTION

[0021] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0022] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0023] In addition, it should be understood that although this specification is described according to the implementation modes, not every implementation mode includes only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art. These other implementation modes are also covered within the protection scope of the present invention.

[0024] As the instruction manual Figure 1 As shown, the present invention discloses a direct upgrading and recycling method based on waste nickel-rich layered positive electrode materials, which adopts crushed waste positive electrode material particles, utilizes LiOH-NaCl-KCl eutectic molten salt system to construct a repair environment, determines the metal mass fraction in the transition metal layer and determines the molar ratio of lithium element to each transition metal element in the transition metal layer, determines the lithium element supplement amount, and then adopts high-temperature heating to simultaneously realize the structural defect repair of the positive electrode material, the introduction of doping elements and the single crystal conversion, thereby realizing the closed-loop direct upgrading and recycling of waste layered positive electrode materials.

[0025] The following steps are involved: (1) Disassembling waste batteries to obtain waste battery positive electrode materials and crushing them with a high-energy ball mill to obtain waste positive electrode material particles; (2) Mixing the waste cathode material particles with a hot alkaline solution, adding the mixture to a reactor, and continuously heating and stirring the mixture to decompose the polyvinylidene fluoride in the waste cathode material particles and remove the electrolyte to obtain a layered metal hydroxide; (3) grinding the obtained layered metal hydroxide and waste positive electrode material particles to obtain a powder mixture, and washing and drying the powder mixture; (4) taking the powder mixture and performing EDTA chemical titration to determine the metal mass fraction of the transition metal layer in the powder mixture, dissolving the powder mixture in aqua regia and performing ICP detection to determine the molar ratio of lithium element in the powder mixture to each transition metal element in the transition metal layer; (5) mixing NaOH-LiOH-KCl solutions according to a molar ratio to construct a molten salt system repair environment, adding the layered metal hydroxide obtained in step (2) and heating; (6) When heated to an appropriate temperature, lithium source and dopant are added to the system and heating is continued until a single crystal material with a smooth surface is no longer produced and the shape is regular and uniform.

[0026] The particle size of the waste positive electrode material particles in step (1) is 2-3 μm.

[0027] The hot alkaline solution in step (2) is a sodium hydroxide solution, and the concentration of the sodium hydroxide solution is 0.5N, wherein N is the molar amount of the metal element in the waste positive electrode material particles, the heating temperature of the reactor is 100-150°C, and the stirring heating time is 2-12h.

[0028] In step (3), the powder mixture is washed with deionized water and vacuum dried at a temperature of 120-140°C.

[0029] The transition metal elements of the transition metal layer in step (4) are nickel, cobalt and manganese.

[0030] In step (5), the molar ratio of NaOH, LiOH and KCl in the NaOH-LiOH-KCl solution is 2:1:2.

[0031] In step (6), when the heating temperature reaches 420-750°C, a lithium source and a dopant are added until the mass fraction of the transition metal layer is 50-60%, and the residual molar content of lithium ions is 0.75-0.85. The heating is continued to 850°C. The lithium source is lithium hydroxide monohydrate and the dopant is Al-ZrO2 powder.

[0032] The present invention also provides an application of the above-mentioned direct upgrading and recycling method based on waste nickel-rich layered positive electrode materials, which is applied to regenerating positive electrode materials for lithium-ion batteries, and converting degraded layered materials into high-voltage and durable positive electrode materials.

[0033] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. Any other changes, modifications, substitutions, combinations, and simplifications made without violating the spirit and principle of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention. In addition, it should be understood that after reading the contents of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application, and all belong to the scope of protection of the present invention.

[0034] Unless otherwise defined, the technical terms used in this document have the same meanings as those generally understood by those skilled in the art to which this application belongs; the use of relevant terms in this document is only for describing specific embodiments and is not intended to limit this application.

[0035] Unless otherwise specified in the present invention, the reagents, instruments, and equipment used are those commonly used by technicians in this field.

[0036] Example 1 LiNi 0.83 Co 0.12 Mn 0.05 O2(SNCM83) This embodiment proposes a method for repairing the environment by constructing a molten salt system to upgrade layered materials to single crystal materials for recycling, including the following steps: First, the waste batteries were disassembled to obtain 20 g of waste battery positive electrode materials, which were then crushed into 2 μm particles using a high-energy ball mill.

[0037] Layered nickel-rich oxide (LO) particles and 5 M NaOH solution were added into a reactor, mixed and heated at 160°C with stirring for 12 h to decompose PVDF and obtain layered metal hydroxide M(OH)2 (M is Ni, Co, or Mn).

[0038] The obtained powder was washed with deionized water and dried in vacuum at 120° C. to obtain a mixed powder.

[0039] The powder mixture was subjected to EDTA chemical titration method, and the mass fraction of the TM layer was obtained to be 52%. The powder was further dissolved in aqua regia and tested by ICP, and the molar ratios of Li / Ni, Li / Co, and Li / Mn were determined to be 0.81:0.83, 0.81:0.12, and 0.81:0.05, respectively.

[0040] Take 10ml 2mol / L NaOH solution, 10mL 1mol / L LiOH solution, and 10ml 2mol / L KCl solution, mix them evenly, and construct a molten salt environment.

[0041] The powder mixture was added into a molten salt environment and heated. When heated to 420°C, 13.7 g of lithium hydroxide monohydrate was added to the mixed system and the heating was maintained. During the heating process from 420 to 750°C, 0.042 g of Al powder and 0.127 g of ZrO2 were gradually added and the mixture was heated to 850°C. No single crystal material with a smooth surface was produced, and the repair process was completed to obtain LiNi 0.83 Co 0.12 Mn 0.05 O2.

[0042] Figure 2 : is a SEM image of the sample prepared in this embodiment, from which it can be seen that the repaired NCM positive electrode material has a good morphology and uniform grains; Figure 3 This is the XRD diagram of the sample prepared in this embodiment. It can be seen from the figure that the NCM positive electrode material has a good layered structure; Figure 5 This is a cycle comparison diagram of the sample application prepared in this embodiment. It can be seen from the figure that the recycled battery material has a high energy retention rate.

[0043] Example 2 LiNi 0.85 Co 0.13 Mn 0.02 O2 The present invention proposes a method for repairing the environment by constructing a molten salt system to upgrade layered materials into single crystal materials for recycling, comprising the following steps: First, the waste batteries were disassembled to obtain 20 g of waste battery positive electrode materials, which were then crushed into 2 μm particles using a high-energy ball mill.

[0044] Layered nickel-rich oxide (LO) particles and 5 M NaOH solution were added into a reactor, mixed and heated at 160°C with stirring for 12 h to decompose PVDF and obtain layered metal hydroxide M(OH)2 (M is Ni, Co, or Mn).

[0045] The obtained powder was washed with deionized water and dried in vacuum at 120° C. to obtain a mixed powder.

[0046] The powder mixture was subjected to EDTA chemical titration method, and the mass fraction of the TM layer was obtained to be 58%. The powder was further dissolved in aqua regia and tested by ICP, and the molar ratios of Li / Ni, Li / Co, and Li / Mn were determined to be 0.79:0.85, 0.79:0.13, and 0.79:0.02, respectively.

[0047] 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 evenly, and construct a molten salt environment.

[0048] Add the powder mixture to the molten salt environment and heat it. When heated to 420°C, add 13.9g of lithium hydroxide monohydrate to the mixed system. Keep heating, and gradually add 0.040g of Al powder and 0.117g of ZrO2 during the heating process from 420 to 750°C. Continue heating to 850°C. When no single crystal material with smooth surface is produced, the repair process is completed.

[0049] Example 3 LiNi 0.88 Co 0.11 Mn 0.01 O2 The present invention proposes a method for repairing the environment by constructing a molten salt system to upgrade layered materials into single crystal materials for recycling, comprising the following steps: First, the waste batteries were disassembled to obtain 20 g of waste battery positive electrode materials, which were then crushed into 2 μm particles using a high-energy ball mill.

[0050] Layered nickel-rich oxide (LO) particles and 5 M NaOH solution were added into a reactor, mixed and heated at 160°C with stirring for 12 h to decompose PVDF and obtain layered metal hydroxide M(OH)2 (M is Ni, Co, or Mn).

[0051] The obtained powder was washed with deionized water and dried in vacuum at 120° C. to obtain a mixed powder.

[0052] The powder mixture was subjected to EDTA chemical titration method, and the mass fraction of TM layer was obtained to be 59%. The powder was further dissolved in aqua regia and tested by ICP, and the molar ratios of Li / Ni, Li / Co, and Li / Mn were determined to be 0.82:0.88, 0.82:0.11, and 0.82:0.01, respectively.

[0053] 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 evenly, and construct a molten salt environment.

[0054] Add the powder mixture to the molten salt environment and heat it. When heated to 420°C, add 13.3g of lithium hydroxide monohydrate to the mixed system. Keep heating, and gradually add 0.041g of Al powder and 0.116g of ZrO2 during the heating process from 420 to 750°C. Continue heating to 850°C. When no single crystal material with smooth surface is produced, the repair process is completed.

[0055] Comparative Example 1: Recovery of lithium from NCM using pyrometallurgy Step 1: Mix pyrometallurgical slag, water and hydrochloric acid to obtain a mixed acid material, wherein the mass ratio of slag: water: hydrochloric acid is 1: (0-2): (1-3), and the concentration of hydrochloric acid is 30wt%; Step 2: The mixed acid material is subjected to a heat-insulating reaction at a temperature of 85° C. for a reaction time of 4 hours, and the pH value at the reaction end point is controlled to be 2.5; Step 3: drying the mixed acid material after the reaction at 300° C. in vacuum to obtain an aluminum-removing material; Step 4: Soak the aluminum-removed material in water for 3 hours to obtain a leaching slurry; Step 5: performing solid-liquid separation on the leached slurry to obtain a leached liquid and a solid A; Step 6: adding lithium sulfate to the leaching solution, filtering, and obtaining a lithium chloride conversion solution and a solid B; Step 7: Separating lithium chloride from other divalent ions in the lithium chloride conversion solution to obtain a lithium chloride solution and a divalent ion salt solution; Step eight: preparing a lithium salt product from a lithium chloride solution.

[0056] The obtained lithium salt product is used as a lithium source to prepare NCM positive electrode material.

[0057] The samples prepared in Example 1 and the samples prepared in Comparative Example 1 were also used in lithium-ion batteries as positive electrode materials. The electrochemical performance of the two was analyzed. The first cycle charge and discharge curves of the two were as follows: Figure 4 As shown: at 3.0-4.6V, 0.1C, the first cycle discharge capacity of Example 1 is higher than that of Comparative Example 1, and the battery energy retention rate performance of Example 1 is better than that of Comparative Example 1.

[0058] Therefore, the present invention adopts the above-mentioned direct upgrading and recycling method and application based on discarded nickel-rich layered positive electrode materials, which effectively recovers lithium, nickel, cobalt and other elements in the layered positive electrode materials of waste batteries while reducing the recycling cost, and further upgrades and recycles them into single crystal positive electrode materials. The battery prepared from the single crystal positive electrode materials recycled by this method has good electrical performance, the recycling method is simple and reasonable, the cost is controllable, the waste is less, and it is suitable for commercial production.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for direct upgrading and recycling of waste nickel-rich layered cathode materials, characterized in that: The waste positive electrode material particles are crushed and the repair environment is constructed using the LiOH-NaCl-KCl eutectic molten salt system. The amount of lithium element supplementation is determined by measuring the metal mass fraction in the transition metal layer and the molar ratio of the lithium element to each transition metal element in the transition metal layer. Subsequently, high-temperature heating is used to simultaneously achieve the structural defect repair, doping element introduction and single crystal conversion of the positive electrode material, thereby realizing the closed-loop direct upgrading and recycling of waste layered positive electrode materials.

2. A method for direct upgrading and recycling of waste nickel-rich layered positive electrode materials according to claim 1, characterized in that: The following steps are involved: (1) Disassembling waste batteries to obtain waste battery positive electrode materials and crushing them with a high-energy ball mill to obtain waste positive electrode material particles; (2) Mixing the waste cathode material particles with a hot alkaline solution, adding the mixture to a reactor, and continuously heating and stirring the mixture to decompose the polyvinylidene fluoride in the waste cathode material particles and remove the electrolyte to obtain a layered metal hydroxide; (3) grinding the obtained layered metal hydroxide and waste positive electrode material particles to obtain a powder mixture, and washing and drying the powder mixture; (4) taking the powder mixture and performing EDTA chemical titration to determine the metal mass fraction of the transition metal layer in the powder mixture, dissolving the powder mixture in aqua regia and performing ICP detection to determine the molar ratio of lithium element in the powder mixture to each transition metal element in the transition metal layer; (5) mixing NaOH-LiOH-KCl solutions according to a molar ratio to construct a molten salt system repair environment, adding the layered metal hydroxide obtained in step (2) and heating; (6) When heated to an appropriate temperature, lithium source and dopant are added to the system and heating is continued until a single crystal material with a smooth surface is no longer produced and the shape is regular and uniform.

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

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

5. A method for direct upgrading and recycling of waste nickel-rich layered positive electrode materials according to claim 2, characterized in that: In step (3), the powder mixture is washed with deionized water and vacuum dried at a temperature of 120-140°C.

6. A method for direct upgrading and recycling of waste nickel-rich layered cathode materials according to claim 2, characterized in that: The transition metal elements of the transition metal layer in step (4) are nickel, cobalt and manganese.

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

2.

8. A method for direct upgrading and recycling of waste nickel-rich layered cathode materials according to claim 2, characterized in that: In step (6), when the heating temperature reaches 420-750°C, a lithium source and a dopant are added until the mass fraction of the transition metal layer is 50-60%, and the residual molar content of lithium ions is 0.75-0.

85. The heating is continued to 850°C. The lithium source is lithium hydroxide monohydrate and the dopant is Al-ZrO2 powder.

9. An application of the method for direct upgrading and recycling of waste nickel-rich layered positive electrode materials according to any one of claims 1 to 8, characterized in that: Used in recycled lithium-ion battery positive electrode materials.

10. The use of a method for direct upgrading and recycling of waste nickel-rich layered positive electrode materials according to claim 9, characterized in that: Applied to degraded layered materials, the degraded layered materials are converted into high-voltage and durable cathode materials.

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