Recovery method and application of metal in nickel cobalt lithium manganate positive plate

Abstract

The invention provides a recovery method and application of metal in a nickel cobalt lithium manganate positive plate. The recycling method comprises the following steps: crushing a nickel cobalt lithium manganate positive plate disassembled from a waste battery, and screening to obtain positive powder; the positive electrode powder and ammonium persulfate are mixed and then calcined at the temperature of 500 DEG C or below, a solid product obtained after calcination is dissolved in water to obtain leachate, and ammonia gas generated after calcination is collected; an ammonia water solution with the concentration of 25-35 wt.% is added into the leachate to be mixed, the pH value is controlled to be 3.5-4.5 through sulfuric acid for a certain time, a first mixed solution is obtained, the first mixed solution is crystallized at the low temperature, then solid-liquid separation is conducted, and double salt crystals containing nickel and cobalt and a second mixed solution containing lithium and manganese are obtained; and adding ammonium sulfide into the second mixed solution containing lithium and manganese to obtain manganese sulfide precipitate and a lithium-containing solution, and evaporating the lithium-containing solution to obtain lithium sulfate and ammonia gas. According to the recovery method, the reaction product is recycled, the problem of waste liquid treatment does not exist, the leachate can be obtained through low-temperature calcination and water leaching, and the energy consumption is low.

Description

Technical Field

[0001] The present invention relates to the technical field of recycling and utilization of lithium-ion batteries, particularly to the recycling and utilization of cathode materials, and more particularly to a method for recycling metals in lithium nickel cobalt manganese oxide cathode sheets. Background Art

[0002] With the rapid industrialization of new energy vehicles, their sales volume will increase exponentially, and the inventory of lithium-ion power batteries will also increase geometrically. At the same time, the environmental pollution problem of waste lithium-ion power batteries and the problem of reasonable resource recycling have become common concerns and urgent problems to be solved in the current industry. The solution of this problem is not only beneficial to environmental protection, but also conducive to the recycling of resources, with great practical significance.

[0003] Currently, the main substances recycled from waste lithium-ion batteries are negative electrode current collectors (commonly copper foils), positive electrode current collectors (commonly aluminum foils), positive electrode active materials, and negative electrode active materials. Among them, the recycling of positive electrode active materials mainly has two methods: wet process and pyrometallurgical process.

[0004] The wet process is to separate metal ions by using a liquid medium. The process conditions are mild and the energy consumption is small. It mainly includes pretreatment, leaching, recovery and other links. The purpose of leaching is to transfer valuable metals in the lithium nickel cobalt manganese oxide cathode material to the leaching solution, which is conducive to subsequent precipitation and purification processes. The wet leaching of the lithium nickel cobalt manganese oxide cathode material of waste lithium-ion batteries is mainly an acid leaching scheme, and inorganic acid (sulfuric acid, hydrochloric acid or nitric acid) + hydrogen peroxide is the most common leaching system. The combination of inorganic acid + hydrogen peroxide can leach the cathode material well, but inorganic acid has strong corrosiveness, high requirements for equipment, and is prone to generate harmful gases. At the same time, the waste liquid needs to be recycled and treated later.

[0005] The pyrometallurgical process generally burns the battery electrode sheets at high temperature to burn off the carbon and organic substances in the broken battery electrode sheets. The remaining ash that cannot be burned is finally screened to obtain a fine powder material containing metals and metal oxides. The traditional pyrometallurgical process mainly includes two types: solid-state reduction and smelting reduction. Among them, solid-state reduction reduces the cathode to metal alloy powder in the form of carbothermal reduction, but subsequent leaching process is still needed for separation. Smelting reduction directly reduces the cathode to liquid metal at high temperature, but there are limitations such as high energy consumption and difficulty in separating the obtained liquid alloy from the slag.

[0006] Therefore, the recycling method of the wet process has problems of high corrosion and waste liquid treatment, and the recycling method of the pyrometallurgical process needs to be carried out at high temperature, with high energy consumption and difficult separation of products. Summary of the Invention

[0007] Based on the above problems, the object of the present invention is to provide a method for recycling metals in a lithium nickel cobalt manganese oxide cathode sheet and its application. This recycling method can recycle reaction products, has no waste liquid treatment problem, and can obtain a leaching solution through low-temperature calcination, with low energy consumption.

[0008] To achieve the above object, in the first aspect of the present invention, a method for recycling metals in a lithium nickel cobalt manganese oxide cathode sheet is provided, including: (1) Preparation of cathode powder Crush the lithium nickel cobalt manganese oxide cathode sheet disassembled from a waste battery and then screen to obtain the cathode powder; (2) Calcination and leaching Mix the cathode powder and ammonium persulfate and then calcine at a temperature below 500°C. Dissolve the calcined solid product in water to obtain a leaching solution, and collect the ammonia gas generated during calcination; (3) Crystallization Add an ammonia water solution with a concentration of 25 - 35 wt.% to the leaching solution, mix, and control the pH value to 3.5 - 4.5 with sulfuric acid for a certain period of time to obtain a first mixed solution. Crystallize the first mixed solution at a low temperature, and then perform solid-liquid separation to obtain a double salt crystal containing nickel and cobalt and a second mixed solution containing lithium and manganese; (4) Separation of lithium and manganese Add ammonium sulfide to the second mixed solution containing lithium and manganese to obtain manganese sulfide precipitate and a lithium-containing solution. Evaporate the lithium-containing solution to obtain lithium sulfate and ammonia gas.

[0009] In the recycling method adopted by the present invention, the liquid-solid sulfonation of ammonium persulfate is utilized to reduce the high-valent metals in the lithium nickel cobalt manganese oxide cathode sheet and convert them into soluble salts by water leaching under relatively low-temperature roasting. This low-temperature roasting method has low energy consumption. Based on the fact that the solubility of Ni and Co double ammonium salts is significantly lower than that of the ammonium sulfate salts of Mn and the ammonium sulfate salt of Li at low temperatures, nickel cobalt and lithium manganese can be separated by low-temperature crystallization and then solid-liquid separation. Further, the reaction of ammonium sulfide can be used to separate lithium and manganese, thereby completing the separation of nickel cobalt manganese heavy metals and lithium. The recycling method adopted by the present invention can only use ammonium persulfate and ammonium sulfide as raw materials, and the generated ammonia gas can be recycled, and there is no waste liquid treatment problem.

[0010] As a technical solution of the present invention, the lithium nickel cobalt manganese oxide cathode sheet includes a cathode active material, a binder, and a conductive agent. The chemical formula of the cathode active material is LiNi x Co y Mn z M (1-x-y-z)O2, wherein M is at least one of Mg, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, V, and Ti, 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z ≤ 1. The binder includes PVDF, and the conductive agent includes at least one of conductive carbon black, conductive graphite, carbon fiber, carbon nanotube, and graphene.

[0011] As a technical solution of the present invention, the lithium nickel cobalt manganese oxide-based positive electrode sheet is mechanically crushed to a particle size of 0.15 - 0.30 mm, and the screening is carried out by coupling a sieve and a vibrating stirrer.

[0012] As a technical solution of the present invention, the particle size of the positive electrode powder is 70 - 90 μm, and the molar ratio of the positive electrode powder to ammonium persulfate is 1:1.0 - 1.5.

[0013] As a technical solution of the present invention, the calcination temperature is 450 - 500 °C and the time is 60 - 80 min.

[0014] As a technical solution of the present invention, the ammonia gas in the calcination leaching step and the ammonia gas in the lithium and manganese separation step are dissolved in water to be used as the ammonia aqueous solution in the crystallization step.

[0015] As a technical solution of the present invention, the certain time is 1 - 2 h and the temperature of the mixed system is 40 - 50 °C.

[0016] As a technical solution of the present invention, the crystallization temperature is 0 - 10 °C and the time is 6 - 10 h.

[0017] As a technical solution of the present invention, the nickel- and cobalt-containing double salt crystal is dissolved in dilute acid and then nickel and cobalt are separated by precipitation, adsorption, or extraction.

[0018] In the second aspect of the present invention, a method for recovering metals in the aforementioned lithium nickel cobalt manganese oxide-based positive electrode sheet is provided to recover metals from the lithium nickel cobalt manganese oxide-based positive electrode sheet. The recovery rate of lithium sulfate is at least 80%, the recovery rate of manganese sulfide is at least 80%, and the recovery rate of the nickel- and cobalt-containing double salt crystal is at least 95%. Detailed Embodiments

[0019] The present invention provides a method for recovering metals in a lithium nickel cobalt manganese oxide-based positive electrode sheet and its application, which can simply realize the separation of Li and heavy metals such as Ni, Co, and Mn, and the high-proportion recovery of metals.

[0020] The lithium nickel cobalt manganese oxide-based positive electrode sheet of the present invention refers to a positive electrode sheet containing a lithium nickel cobalt manganese oxide-based positive electrode active material. The lithium nickel cobalt manganese oxide-based positive electrode sheet includes a positive electrode active material, a binder, and a conductive agent. The positive electrode active material includes a lithium nickel cobalt manganese oxide-based positive electrode active material, and its chemical formula is LiNix Co y Mn z M (1-x-y-z) O₂, where M is at least one of Mg, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, V, and Ti, 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z ≤ 1. The binder includes PVDF. The conductive agent includes at least one of conductive carbon black, conductive graphite, carbon fiber, carbon nanotube, and graphene. The mass ratio of the positive electrode active material, binder, and conductive agent can be, but is not limited to, 85 - 98:0.5 - 3.0:0.5 - 3.0. The positive electrode active material, binder, and conductive agent are made into a slurry using a solvent and coated on the positive electrode current collector, followed by drying, rolling, etc. to obtain the positive electrode sheet.

[0021] The method for recovering metals in the lithium nickel cobalt manganese oxide-based positive electrode sheet of the present invention includes the following steps.

[0022] (1) Preparation of positive electrode powder The lithium nickel cobalt manganese oxide-based positive electrode sheet disassembled from the waste battery is crushed and then screened to obtain the positive electrode powder.

[0023] (2) Calcination and leaching The positive electrode powder and ammonium persulfate are mixed and then calcined. The calcined solid product is dissolved in water to obtain the leaching solution, and the ammonia gas generated during calcination is collected.

[0024] (3) Crystallization The ammonia water solution is added to the leaching solution and mixed, and the pH value is controlled at 3.5 - 4.5 with sulfuric acid for a certain period of time to obtain the first mixed solution. The first mixed solution is crystallized at a low temperature, and then solid-liquid separation is performed to obtain the double salt crystal containing nickel and cobalt and the second mixed solution containing lithium and manganese.

[0025] (4) Separation of lithium and manganese Ammonium sulfide is added to the second mixed solution containing lithium and manganese to obtain manganese sulfide precipitate and a lithium-containing solution. The lithium-containing solution is evaporated to obtain lithium sulfate and ammonia gas.

[0026] Among them, in step (1), the lithium nickel cobalt manganese oxide-based positive electrode sheet is mechanically crushed to a particle size of 0.15 - 0.30 mm, and screening is performed using a combination of a sieve mesh and a vibration stirrer. The sieve mesh can be 200 mesh. The particle size of the positive electrode powder obtained after crushing and screening is 70 - 90 μm. By way of example, the particle size can be, but is not limited to, 70 μm, 72 μm, 74 μm, 76 μm, 78 μm, 80 μm, 82 μm, 84 μm, 86 μm, 88 μm, 90 μm.

[0027] In step (2), the molar ratio of the positive electrode powder material to ammonium persulfate is 1:1.0 to 1.5. As an example, the molar ratio can be, but is not limited to, 1:1.0, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5. The calcination is carried out at a temperature below 500 °C. Further, the calcination temperature is 450 to 500 °C. As an example, the temperature can be, but is not limited to, 450 °C, 460 °C, 470 °C, 480 °C, 490 °C, 500 °C. The calcination time is 60 to 80 min. As an example, it can be, but is not limited to, 60 min, 62 min, 64 min, 66 min, 68 min, 70 min, 72 min, 74 min, 76 min, 80 min.

[0028] In step (2), the lithium nickel cobalt manganese oxide-based positive electrode active material and ammonium persulfate undergo an oxidation-reduction reaction to reduce the high-valent metal and convert it into a soluble salt. The reaction is shown in Equation (1). The ammonia gas generated by the reaction is collected with water and can be used in step (3).

[0029] LiNi x Co y Mn z O2+(NH4)2S2O4→Li2SO4+NiSO4+CoSO4+MnSO4+NH3 (where x + y + z = 1, 0 < x < 1, 0 < y < 1, 0 < z < 1) Equation (1) In step (3), the ammonia aqueous solution is sourced from the ammonia gas in the calcination leaching step and the ammonia gas in the lithium and manganese separation step. The ammonia gas is collected with water and can be further diluted or concentrated into an ammonia aqueous solution with a concentration of 25 - 35 wt.% for use in the crystallization step. The concentration of the ammonia aqueous solution can be, but is not limited to, 25 wt.%, 26 wt.%, 27 wt.%, 28 wt.%, 29 wt.%, 30 wt.%, 31 wt.%, 32 wt.%, 33 wt.%, 34 wt.%, 35 wt.%. Mix the ammonia aqueous solution and the water leaching solution and adjust the pH of the system to 3.5 - 4.5 with dilute sulfuric acid below 10 wt.%. Control the temperature of the system at 40 - 50 °C and stir evenly for 1 - 2 h to obtain ammonium sulfate mixed salts. In this reaction, the pH can be 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, and the stirring time can be 1 h, 2 h. At low temperature, the ammonium salts of Ni and Co undergo a co-crystallization reaction as shown in Equation (2) to form Ni, Co double ammonium salts. Since the solubility of Ni, Co double ammonium salts is significantly lower than that of ammonium sulfate salts of Mn ((NH4)2Mn(SO4)2) and Li (NH4LiSO4), nickel-cobalt and lithium-manganese can be separated by low-temperature crystallization followed by solid-liquid separation. The crystallization temperature is 0 - 10 °C. As an example, the temperature can be, but is not limited to, 0 °C, 1 °C, 2 °C, 3 °C, 4 °C, 5 °C, 6 °C, 7 °C, 8 °C, 9 °C, 10 °C, and the crystallization time is 6 - 10 h. As an example, the time can be, but is not limited to, 6 h, 7 h, 8 h, 9 h, 10 h.

[0030] (NH4)2SO4 + xNiSO4 + (1 - x)CoSO4 + 6H2O → (NH4)2Ni x Co (1-X) (SO4)2·6H2O Equation (2) In the lithium and manganese separation in step (4), add ammonium sulfide to the second mixed solution containing lithium and manganese. Lithium and manganese can be separated by the formed manganese sulfide precipitate. Evaporate the obtained lithium-containing solution (containing NH4LiSO4 and LiSO4) to obtain lithium sulfate and ammonia gas. The ammonia gas can be collected with water and can be further diluted or concentrated into an ammonia aqueous solution with a concentration of 25 - 35 wt.% for use in the crystallization step.

[0031] The prepared Ni, Co double ammonium salts can be directly used as raw materials for preparing cathode active materials, or Ni and Co can be further separated. For example, the double salt crystals containing nickel and cobalt can be dissolved in dilute acid and then nickel and cobalt can be separated by precipitation, adsorption or extraction. The precipitation can be to precipitate Ni 2+ and Co 2+Adsorption is carried out using different adsorption resins (such as chelating resins containing phosphoric acid groups, phosphorous acid groups, sulfonic acid groups, hypophosphorous acid groups or amino groups; biochars obtained by pyrolysis of peanut shells, reed straws, bamboo husks, buckwheat husks, rice straws or pomelo peels) to treat Ni by chelation or adsorption 2+ or Co 2+ Extraction is carried out using different extractants (such as Mextral 54-100 1-phenyl-1,3-decanedione, P507 2-ethylhexyl phosphoric acid-2-ethylhexyl ester and C272 bis(2,4,4-trimethylpentyl) phosphonic acid) to extract Ni 2+ or Co 2+ .

[0032] In addition, the solid-liquid separation in the crystallization step can be centrifugation, filtration, suction filtration, etc.

[0033] To better illustrate the purpose, technical solution and beneficial effects of the present invention, the present invention will be further described below in conjunction with specific embodiments. It should be noted that the methods described in the following embodiments are further explanatory descriptions of the present invention and should not be regarded as limitations of the present invention.

[0034] Example 1 This example is a method for recovering metals in a lithium nickel cobalt manganese oxide cathode sheet, and the steps are as follows.

[0035] (1) Preparation of cathode powder After the lithium nickel cobalt manganese oxide cathode sheet disassembled from the waste 1# battery is mechanically crushed to a particle size of about 0.20 mm, it is screened by coupling a 200-mesh sieve and a vibration stirrer to obtain a cathode powder with a particle size of 80 μm.

[0036] (2) Calcination leaching The cathode powder and ammonium persulfate are mixed at a molar ratio of 1:1.2 and calcined at 460 °C for 60 min. The calcined solid product is dissolved in water to obtain a leaching solution, and the ammonia gas generated after calcination is collected with water. (3) Crystallization The collected water is concentrated to an ammonia water solution with a concentration of 30 wt.%, added to the leaching solution and mixed, and the pH value is controlled at 4.0 with sulfuric acid. After controlling the temperature at 45 °C for 1 h, a first mixed solution is obtained. The first mixed solution is crystallized at 5-7 °C for 7 h, and then filtered to obtain a double salt crystal containing nickel and cobalt and a second mixed solution containing lithium and manganese.

[0037] (4) Separation of lithium and manganese Ammonium sulfide is added to the second mixed solution containing lithium and manganese to obtain manganese sulfide precipitate and a lithium-containing solution. The lithium-containing solution is evaporated to obtain lithium sulfate and ammonia gas, and the generated ammonia gas is collected with water.

[0038] Example 2 This example is a method for recovering metals in a lithium nickel cobalt manganese oxide cathode sheet, and the steps are as follows.

[0039] (1) Preparation of cathode powder After the lithium nickel cobalt manganese oxide cathode sheet disassembled from the used #2 battery is mechanically crushed to a particle size of about 0.25 mm, it is screened by coupling a 200-mesh sieve and a vibration stirrer to obtain cathode powder with a particle size of 90 μm.

[0040] (2) Calcination and leaching The cathode powder and ammonium persulfate are mixed at a molar ratio of 1:1.4 and then calcined at 480 °C for 75 min. The calcined solid product is dissolved in water to obtain a leaching solution, and the ammonia gas generated after calcination is collected with water. (3) Crystallization The collected water is concentrated to an ammonia water solution with a concentration of 32 wt.%, added to the leaching solution and mixed, and the pH value is controlled to 3.8 with sulfuric acid. After controlling the temperature at 50 °C for 2 h, a first mixed solution is obtained. The first mixed solution is crystallized at 2 - 4 °C for 10 h, and then filtered to obtain a double salt crystal containing nickel and cobalt and a second mixed solution containing lithium and manganese.

[0041] (4) Separation of lithium and manganese Ammonium sulfide is added to the second mixed solution containing lithium and manganese to obtain manganese sulfide precipitate and a lithium-containing solution. The lithium-containing solution is evaporated to obtain lithium sulfate and ammonia gas, and the generated ammonia gas is collected with water.

[0042] Example 3 This example is a method for recovering metals in a lithium nickel cobalt manganese oxide cathode sheet, and the steps are as follows.

[0043] (1) Preparation of cathode powder After the lithium nickel cobalt manganese oxide cathode sheet disassembled from the used #3 battery is mechanically crushed to a particle size of about 0.20 mm, it is screened by coupling a 200-mesh sieve and a vibration stirrer to obtain cathode powder with a particle size of 80 μm.

[0044] (2) Calcination and leaching The cathode powder and ammonium persulfate are mixed at a molar ratio of 1:1.0 and then calcined at 500 °C for 80 min. The calcined solid product is dissolved in water to obtain a leaching solution, and the ammonia gas generated after calcination is collected with water. (3) Crystallization The collected water is concentrated to an ammonia water solution with a concentration of 35 wt.%, added to the leaching solution and mixed, and the pH value is controlled to 4.2 with sulfuric acid. After controlling the temperature at 40 °C for 2 h, a first mixed solution is obtained. The first mixed solution is crystallized at 5 - 7 °C for 8 h, and then filtered to obtain a double salt crystal containing nickel and cobalt and a second mixed solution containing lithium and manganese.

[0045] (4) Separation of lithium and manganese Ammonium sulfide is added to the second mixed solution containing lithium and manganese to obtain manganese sulfide precipitate and a lithium-containing solution. The lithium-containing solution is evaporated to obtain lithium sulfate and ammonia gas, and the generated ammonia gas is collected with water.

[0046] Example 4 This example is a method for recovering metals in a lithium nickel cobalt manganese oxide cathode sheet, and the steps are as follows.

[0047] (1) Preparation of cathode powder The lithium nickel cobalt manganese oxide cathode sheet disassembled from the used Battery No. 1 is mechanically crushed to a particle size of about 0.20 mm, and then screened with a 200-mesh sieve and a vibrating stirrer to obtain cathode powder with a particle size of 80 μm.

[0048] (2) Calcination and leaching The cathode powder and ammonium persulfate are mixed at a molar ratio of 1:1.2 and calcined at 460 °C for 60 min. The calcined solid product is dissolved in water to obtain a leaching solution, and the ammonia gas generated during calcination is collected with water. (3) Crystallization The collected water is concentrated to an ammonia water solution with a concentration of 30 wt.%, added to the leaching solution and mixed, and the pH value is controlled at 4.0 with sulfuric acid. After controlling the temperature at 45 °C for 1 h, a first mixed solution is obtained. The first mixed solution is crystallized at 5 - 7 °C for 7 h, and then filtered to obtain a double salt crystal containing nickel and cobalt and a second mixed solution containing lithium and manganese.

[0049] (4) Separation of lithium and manganese Ammonium sulfide is added to the second mixed solution containing lithium and manganese to obtain manganese sulfide precipitate and a lithium-containing solution. The lithium-containing solution is evaporated to obtain lithium sulfate and ammonia gas, and the generated ammonia gas is collected with water.

[0050] (5) Separation of nickel and cobalt The double salt crystal containing nickel and cobalt is dissolved in 4 wt.% dilute sulfuric acid, and then added to an adsorption column filled with chelating resin HP-C / N-1 for adsorption to obtain adsorbed effluent. The adsorption column is desorbed with 4.0 wt.% dilute sulfuric acid to recover cobalt, and then cobalt is precipitated and recovered with 10.0 wt.% sodium hydroxide solution. The adsorbed effluent is neutralized with 10.0 wt.% sodium hydroxide solution, and nickel is recovered after precipitation.

[0051] Table 1 Metal recovery rates of Examples 1 - 4

[0052] As can be seen from the results in Table 1, the recovery methods of Examples 1 - 4 can be separated and recovered step by step through the liquid-solid sulfonation of ammonium persulfate combined with low-temperature roasting, and then combined with the different solubilities of different ammonium sulfate salts at low temperature, and the recovery rates are relatively high.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, it is not limited to the embodiments listed. Those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for recovering metals in a lithium nickel cobalt manganese oxide cathode sheet, characterized in that, Comprising: (1) Preparing the positive electrode powder Crushing and screening the lithium nickel cobalt manganese oxide-based positive electrode sheet disassembled from the waste battery to obtain the positive electrode powder; (2) Calcining and leaching Mixing the positive electrode powder and ammonium persulfate, and calcining at a temperature below 500 °C. Dissolving the calcined solid product in water to obtain a leaching solution, and collecting the ammonia gas generated after calcination; (3) Crystallization Adding an ammonia water solution with a concentration of 25-35 wt.% to the leaching solution, mixing, and controlling the pH value to 3.5-4.5 with sulfuric acid for a certain time to obtain a first mixed solution. Crystallizing the first mixed solution at a low temperature, and then performing solid-liquid separation to obtain a double salt crystal containing nickel and cobalt and a second mixed solution containing lithium and manganese; (4) Separating lithium and manganese Adding ammonium sulfide to the second mixed solution containing lithium and manganese to obtain a manganese sulfide precipitate and a lithium-containing solution. Evaporating the lithium-containing solution to obtain lithium sulfate and ammonia gas.

2. The method for recycling metals in the lithium nickel cobalt manganese oxide cathode sheet according to claim 1, characterized in that, The lithium nickel cobalt manganese oxide-based positive electrode sheet includes a positive electrode active material, a binder, and a conductive agent. The chemical formula of the positive electrode active material is LiNi x Co y Mn z M (1-x-y-z) O2, where M is at least one of Mg, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, V, and Ti, 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z ≤ 1. The binder includes PVDF, and the conductive agent includes at least one of conductive carbon black, conductive graphite, carbon fiber, carbon nanotube, and graphene.

3. The method for recovering metals in the lithium nickel cobalt manganese oxide cathode sheet according to claim 1, characterized in that, The lithium nickel cobalt manganese oxide-based positive electrode sheet is mechanically crushed to a particle size of 0.15-0.30 mm, and the screening is carried out by coupling a sieve and a vibrating stirrer.

4. The method for recovering metals in the lithium nickel cobalt manganese oxide cathode sheet according to claim 1, characterized in that, The particle size of the positive electrode powder is 70-90 μm, and the molar ratio of the positive electrode powder to ammonium persulfate is 1:1.0-1.

5.

5. The method for recovering metals in the lithium nickel cobalt manganese oxide cathode sheet according to claim 1, characterized in that, The temperature of the calcination is 450-500 °C, and the time is 60-80 min.

6. The method for recycling metals in the lithium nickel cobalt manganese oxide cathode sheet according to claim 1, wherein The ammonia gas in the calcining and leaching step and the ammonia gas in the lithium and manganese separation step are dissolved in water to be used as the ammonia water solution in the crystallization step.

7. The method for recycling metals in the lithium nickel cobalt manganese oxide cathode sheet according to claim 1, characterized in that, The certain time is 1-2 h, and the temperature of the mixed system is 40-50 °C.

8. The method for recovering metals in the lithium nickel cobalt manganese oxide cathode sheet according to claim 1, wherein The temperature of the crystallization is 0-10 °C, and the time is 6-10 h.

9. The method for recycling metals in the lithium nickel cobalt manganese oxide cathode sheet according to claim 1, characterized in that, Dissolving the double salt crystal containing nickel and cobalt in dilute acid, and then separating nickel and cobalt by precipitation, adsorption or extraction.

10. Recycling the metals in the lithium nickel cobalt manganese oxide cathode sheet according to the method for recycling metals in the lithium nickel cobalt manganese oxide cathode sheet according to any one of claims 1 to 9, characterized in that, The recovery rate of lithium sulfate is at least 80%, the recovery rate of manganese sulfide is at least 80%, and the recovery rate of the double salt crystal containing nickel and cobalt is at least 95%.

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