Method and equipment for recycling positive electrode active materials of lithium-ion batteries

Abstract

The present invention provides a method and equipment for recovering positive electrode active materials of lithium-ion batteries, wherein the recovery method comprises the following steps: (1) soaking scrapped positive electrode sheets in NMP, heating to dissolve the binder in the positive electrode sheets in the NMP, filtering, and drying to obtain a positive electrode waste material; and (2) adding LiNO3 and LiOH eutectic lithium salts to the positive electrode waste material, mixing them evenly, and then using a solid-phase method to repair the positive electrode waste material with lithium, followed by high-temperature sintering. The present invention dissolves the binder in NMP to separate the positive electrode waste material from the current collector, and then performs solid-phase lithium repair with the eutectic lithium salt, and then performs high-temperature sintering to obtain the positive electrode active material. The use of eutectic lithium salts has a lower sintering temperature, and at a lower sintering temperature, the melted lithium salt can penetrate into the surface and interior of the positive electrode waste material, making the sintered and repaired positive electrode active material more uniform. The use of a solid-phase method for one-step sintering has a high recovery rate and avoids the need to prepare an intermediate product in a hydrothermal reaction and then wash and calcine the intermediate product.

Description

Technical Field

[0001] The present invention relates to the technical field of material preparation, processing-related processes and equipment, and in particular to a recycling method and recycling equipment, and more particularly to a recycling method and recycling equipment for lithium-ion battery positive electrode active materials. Background Art

[0002] Lithium-ion batteries, with their advantages of high energy density, high voltage, excellent cycle performance, low self-discharge, long storage life, safe operation, wide operating temperature range, and environmental friendliness, are gradually replacing traditional nickel-cadmium and nickel-metal hydride batteries, and their market share is increasing year by year. The precious metal resources in lithium-ion batteries are concentrated in the casing, current collector, and positive electrode active material.

[0003] Currently, in addition to the early commercialization of lithium cobalt oxide (LCO), other commonly used cathode active materials for lithium-ion batteries in industrial production include spinel-structured lithium manganese oxide (LMO), layered nickel-cobalt-manganese oxide (NiCoMnO) ternary materials, and olivine-type lithium iron phosphate (LiFePO). Due to their limited cycle life, lithium-ion batteries must be discarded after a period of use. The organic solvents and metals in LMOs can pollute soil, air, and water sources, posing a significant environmental threat. Furthermore, the metals contained in spent LMOs are often a scarce resource. Exploring effective recycling methods for spent LMOs and effectively utilizing the precious metals in these batteries is urgent. Currently, the use of strong inorganic acids to separate and purify the cobalt and lithium metals in LMO cathode active materials is a popular approach. However, this process is complex, requires high-quality equipment, and can result in significant secondary pollution. Research on the recycling of LMO and NiCoMnO cathode active materials is limited.

[0004] Currently, the primary industrial method for processing spent lithium-ion batteries containing nickel-cobalt-manganese oxide (NiCoMnO) as the active cathode material is to crush and separate the spent lithium-ion batteries to obtain ternary cathode powder, then remove impurities from the resulting ternary cathode powder using pyrolysis or wet leaching methods. Finally, the powder is recovered as a whole or separately through co-precipitation or extraction separation. However, traditional pyrolysis recycling processes suffer from high energy consumption and low recovery rates. While wet treatments offer higher recovery rates, they also suffer from low metal separation rates, high costs, complex processes, and severe environmental pollution. Summary of the Invention

[0005] The purpose of the present invention is to provide an effective method and equipment for recycling positive electrode active materials of lithium-ion batteries, which can recycle the positive electrode active materials of lithium batteries to avoid wasting resources and polluting the environment, and repair and regenerate the recovered positive electrode active materials to achieve the purpose of reuse. The process is simple, the cost is low, and the recovery rate is high.

[0006] To achieve the above object, the first aspect of the present invention provides a method for recovering positive electrode active materials of lithium ion batteries, comprising the steps of:

[0007] (1) Soaking the scrapped positive electrode sheet in NMP, heating to dissolve the binder in the positive electrode sheet in the NMP, filtering and drying to obtain the positive electrode waste material;

[0008] (2) LiNO3 and LiOH eutectic lithium salts are added to the positive electrode waste material, mixed evenly, and then lithium supplemented and repaired by a solid phase method, followed by high-temperature sintering.

[0009] Compared to existing technologies, the present recovery method uses NMP to dissolve the binder, separating the cathode waste material from the current collector. This is then followed by solid-phase lithium remediation with a eutectic lithium salt, followed by high-temperature sintering to produce the cathode active material. The use of LiNO3 and LiOH as eutectic lithium salts allows for a relatively low sintering temperature, allowing the melted lithium salt to penetrate the surface and interior of the cathode waste material, resulting in a more uniform sintered cathode active material. The solid-phase sintering method achieves a high recovery rate by performing a single-step sintering process, avoiding the need for hydrothermal reaction to prepare an intermediate product, followed by cleaning and calcination of the intermediate product.

[0010] As a preferred technical solution of the present invention, the drying temperature in step (1) is higher than the heating temperature. The material is first heated at a temperature of about 70°C to dissolve the binder such as PVDF in the positive electrode sheet in NMP. After filtering out the NMP, the material is dried at a temperature of about 110°C to remove the NMP in the positive electrode waste material.

[0011] As a preferred technical solution of the present invention, the molar ratio of the LiNO3 and the LiOH is 2 to 4:2, preferably 3:2. At this molar ratio, a low eutectic point will appear, and the melting point is less than 200°C (that is, this melting point is lower than the melting point of each pure component), which is conducive to reducing the sintering temperature.

[0012] As a preferred technical solution of the present invention, the solid-phase method has a reaction temperature of 260-350°C and a reaction time of 2-4 hours, and the sintering temperature is 750-950°C and the reaction time is 3-5 hours. Taking advantage of the low melting point of the eutectic lithium salt, the reaction temperature can be lowered. Lithium can be replenished between the solid and liquid phases at a reaction temperature of 260-350°C. The subsequent high-temperature sintering at 750-950°C can achieve a more thorough reaction and adjust the crystal structure.

[0013] The second aspect of the present invention provides a recycling device for lithium-ion battery positive electrode active materials, comprising a recovery tank connected in sequence for dissolving the binder in the positive electrode sheet and recovering the positive electrode waste material, a first conveying mechanism for conveying the positive electrode waste material, a powder mixing tank for mixing the positive electrode waste material with LiNO3 and LiOH eutectic lithium salt, a second conveying mechanism for conveying the mixed powder, and a sintering furnace for solid-phase reaction and sintering the powder.

[0014] By using the recycling equipment of the present invention, the pole pieces are dissolved in a recovery tank to obtain scrapped positive electrode active materials and conductive agents, which are then mixed with LiNO3 and LiOH eutectic lithium salts in a powder mixing tank. Finally, the conductive agent is removed by high-temperature sintering to obtain the positive electrode active material that has been repaired by lithium supplementation. This recycling equipment is simple, low-cost, and easy to operate.

[0015] As a preferred technical solution of the present invention, the upper sides of the recovery tank are respectively provided with a positive electrode sheet feed port and an NMP feed port. The interior of the recovery tank is sequentially provided with a first screen for intercepting the positive electrode current collector and a second screen for intercepting the positive electrode waste material from top to bottom. The recovery tank is provided with an NMP discharge port below the second screen. The recovery tank is also provided with a heating mechanism for heating NMP and a discharge port connected to the first conveying mechanism. The mesh number of the first screen is lower than that of the second screen. The first screen preferably has a mesh number of 200 and the second screen preferably has a mesh number of 400. After the binder of the positive electrode sheet is dissolved by NMP, the positive electrode waste material and NMP flow through the first screen to the second screen, while the positive electrode current collector is intercepted. Then, through the second screen with a smaller pore size, the positive electrode waste material is intercepted, and NMP flows to the bottom of the recovery tank through the second screen. The heating mechanism performs multiple heating operations. The first heating is performed at a low temperature, such as about 70°C, for dissolution. After the NMP is discharged from the recovery tank, the NMP in the positive electrode waste material is heated at 110°C to evaporate and discharge it.

[0016] As a preferred technical solution of the present invention, the recovery tank is provided with an exhaust port between the first screen and the second screen, and the NMP in the positive electrode waste material placed on the second screen evaporates after drying and is discharged through the exhaust port.

[0017] As a preferred technical solution of the present invention, the bottom surface of the discharge port and the second screen are located on the same horizontal plane, and the first conveying mechanism includes a conveyor belt and a transport pallet that moves with the conveyor belt and matches the height of the discharge port.

[0018] As a preferred technical solution of the present invention, the upper sides of the powder mixing tank are respectively provided with a positive electrode waste material feed port and a eutectic lithium salt feed port connected to the first conveying mechanism, and the lower part of the powder mixing tank is provided with a discharge pipe.

[0019] As a preferred technical solution of the present invention, the bottom wall of the inner cavity of the powder mixing tank is an arc-shaped structure, and the bottom end extends to the discharge pipe. The discharge pipe wall is provided with a vent, and the discharge pipe is equipped with a valve to control the opening or closing of the vent. The arc-shaped bottom wall of the inner cavity of the powder mixing tank is configured to facilitate the aggregation of powder. The vent is provided at the end of the discharge pipe connected to it. After the gas is introduced, the accumulated powder can be blown away by the compressed air, thereby achieving the effect of evenly dispersing the powder.

[0020] As a preferred technical solution of the present invention, the second conveying mechanism is located below the discharge pipe, and the second conveying mechanism includes a conveying belt and a sagger that moves with the conveying belt and is located below the discharge pipe.

[0021] As a preferred technical solution of the present invention, the sintering furnace is provided with a powder feed port connected to the second conveying mechanism, and the bottom of the sintering furnace is provided with a positive electrode active material discharge port. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the recycling equipment for lithium-ion battery positive electrode active materials of the present invention.

[0023] Component Symbol Description

[0024] 100-recycling equipment; 10-recycling tank; 11-positive electrode sheet feed port; 12-NMP feed port; 13-first screen; 14-second screen; 15-NMP discharge port; 16-discharge port; 17-exhaust port; 20-first conveying mechanism; 21 / 41-conveying belt; 23-transport pallet; 30-powder mixing tank; 31-positive electrode waste material feed port; 32-eutectic lithium salt feed port; 33-discharge pipe; 34-inner cavity bottom wall; 35-vent; 36-valve; 40-second conveying mechanism; 43-sagger; 50-sintering furnace; 51-powder feed port; 53-positive electrode active material discharge port DETAILED DESCRIPTION

[0025] The method for recycling positive electrode active materials of lithium-ion batteries of the present invention comprises first separating the positive electrode waste materials, then performing lithium replenishment, repair and sintering. The specific steps may include:

[0026] (1) Soaking the scrapped positive electrode sheet in NMP, heating it to dissolve the binder in the positive electrode sheet in the NMP, filtering and drying it to obtain the positive electrode waste material;

[0027] (2) LiNO3 and LiOH eutectic lithium salts are added to the positive electrode waste material, mixed evenly, and then lithium replenishment and repair are performed using a solid phase method, followed by high-temperature sintering.

[0028] The drying temperature in step (1) is higher than the heating temperature. The heating temperature can be about 70° C. for 1 hour, and the drying temperature is about 110° C. The positive electrode waste material includes a positive electrode active material and a conductive agent. The positive electrode active material can be a commonly used positive electrode active material, such as lithium manganese oxide, lithium nickel cobalt manganese oxide, lithium cobalt oxide, lithium iron phosphate, etc. The conductive agent can be Super-P, Ketjen black, acetylene black, KS-6, KS-15, VGCG, or CNT.

[0029] In step (2), the molar ratio of LiNO3 and LiOH is 2 to 4:2, preferably 3:2. At this molar ratio, a low eutectic point will appear, and the melting point is less than 200°C (i.e., this melting point is lower than the melting point of each pure component), which is conducive to reducing the sintering temperature. The reaction temperature of the solid-phase method is 260 to 350°C, the reaction time is 2 to 4 hours, and the sintering temperature is 750 to 950°C, and the time is 3 to 5 hours. The low melting point of the eutectic lithium salt can be used to reduce the reaction temperature. At a reaction temperature of 260 to 350°C, lithium can be supplemented between the solid and liquid, and the subsequent high-temperature sintering at 750 to 950°C can make the reaction more thorough and adjust the crystal structure at the same time.

[0030] The recovery method of the lithium ion battery positive electrode active material of the present invention can be adopted as follows Figure 1 The recycling equipment shown, the recycling equipment 100 for lithium-ion battery positive active materials includes a recovery tank 10 connected in sequence for dissolving the binder in the positive electrode sheet and recovering the positive electrode waste material, a first conveying mechanism 20 for conveying the positive electrode waste material, a powder mixing tank 30 for mixing the positive electrode waste material with LiNO3 and LiOH eutectic lithium salt, a second conveying mechanism 40 for conveying the mixed powder and a sintering furnace 50 for solid-phase reaction and sintering the powder.

[0031] Continue as Figure 1As shown, a positive electrode sheet feeding port 11 and an NMP feeding port 12 are respectively provided on both sides of the upper part of the recovery tank 10. The interior of the recovery tank 10 is provided with a first screen 13 for intercepting the positive electrode current collector and a second screen 14 for intercepting the positive electrode waste material from top to bottom. The recovery tank 10 is provided with an NMP discharge port 15 below the second screen 14. The recovery tank 10 is also provided with a heating mechanism for heating NMP (not shown in the figure) and a discharge port 16 connected to the first conveying mechanism 20. An exhaust port 17 is provided between the first screen 13 and the second screen 14. The mesh size of the first screen 13 is lower than that of the second screen 14. The mesh size of the first screen 13 is preferably 200 mesh, and the mesh size of the second screen 14 is preferably 400 mesh. After the binder of the positive electrode sheet is dissolved by NMP, the positive electrode waste material and NMP flow through the first screen 13 to the second screen 14, while the positive electrode current collector is intercepted. The positive electrode waste material then passes through the second screen 14 with a smaller pore size, where the positive electrode waste material is intercepted, while the NMP flows through the second screen 14 to the bottom of the recovery tank 10. The heating mechanism can be a heating element such as a heating plate, a resistance wire, or a heating film provided on the peripheral wall and / or bottom of the recovery tank 10. The heating mechanism can perform multiple heating operations, initially at a low temperature, such as about 70°C, for dissolution heating. After the NMP is discharged from the recovery tank 10, it is heated again at 110°C to evaporate the NMP in the positive electrode waste material and discharge it through the exhaust port 17. In addition, the bottom of the discharge port 16 and the second screen 14 are located at the same horizontal plane, and the first conveying mechanism 20 includes a conveyor belt 21 and a transport tray 23 that moves with the conveyor belt 21 and matches the height of the discharge port 16 .

[0032] Continue as Figure 1 As shown, the upper side of the powder mixing tank 30 is provided with a positive electrode waste material feed port 31 and a eutectic lithium salt feed port 32, respectively, connected to the first conveying mechanism 20. A discharge pipe 33 is provided at the lower portion of the powder mixing tank 30. The bottom wall 34 of the inner cavity of the powder mixing tank 30 is an arc-shaped structure, and its bottom end extends to the discharge pipe 33. The wall of the discharge pipe 33 is provided with a vent 35, and the discharge pipe 33 is equipped with a valve 36 to control the opening or closing of the vent. The arc-shaped bottom wall 34 of the inner cavity of the powder mixing tank 30 is configured to facilitate the aggregation of powder. The vent 35 is provided at the end of the discharge pipe 33 connected thereto. After the gas is introduced, the accumulated powder can be blown away by the compressed air, thereby achieving the effect of evenly dispersing the powder.

[0033] Combine Figure 1It should be further explained that the second conveying mechanism 40 is located below the discharge pipe 33, and the second conveying mechanism 40 includes a conveyor belt 41 and a sagger 43 that moves with the conveyor belt 41 and is located below the discharge pipe 33. The sintering furnace 50 is provided with a powder feed port 51 connected to the second conveying mechanism 40, and a positive electrode active material discharge port 53 is provided at the bottom of the sintering furnace 50 for collecting the repaired positive electrode active material, wherein the conductive agent is vaporized during high-temperature sintering. Among them, the positive electrode sheet feed port 11, NMP feed port 12, NMP discharge port 15, discharge port 16, exhaust port 17, positive electrode waste material feed port 31, eutectic lithium salt feed port 32, vent 35, powder feed port 51, and positive electrode active material discharge port 53 can all be controlled to open or close by valves.

[0034] The operating principle of the lithium-ion battery positive electrode active material recovery equipment 100 of the present invention is as follows: scrapped positive electrode sheets are cut into sheets and added to the first screen 13 of the recovery tank 10 through the positive electrode sheet feed port 11. NMP is added through the NMP feed port 12. The heating mechanism is turned on to heat the NMP solution to 70°C. The solution is heated for a certain period of time to dissolve the binder in the NMP. The positive electrode waste material falls off the positive electrode current collector and falls onto the second screen 14. The NMP is discharged from the NMP discharge port 15. The recovery tank 10 is heated again to a temperature of 110°C to dry the NMP in the positive electrode waste material to obtain dry positive electrode waste material. During the drying process, the NMP evaporates and is discharged through the exhaust port 17. The positive electrode waste material is transported to the powder mixing tank 30 via the transport tray 23 and the conveyor belt 21 through the positive electrode waste material feeding port, LiNO3 and LiOH are added through the eutectic lithium salt feeding port 32, the valve 36 is closed, and compressed gas is introduced into the powder mixing tank 30 through the vent 35 to mix the eutectic lithium salt and the positive electrode waste material evenly, the vent 35 is closed, the valve 36 is opened, the powder is discharged from the discharge pipe 33, and the powder is transported to the sintering furnace 50 through the sagger 43 of the second conveying mechanism 40, and the sintering temperature is 260-350°C, the reaction time is 2-4 hours, and then it is calcined at 750-950°C for 3-5 hours. At this time, the conductive agent is gasified, and the positive electrode waste material is repaired and regenerated to obtain the positive electrode active material.

[0035] The lithium-ion battery positive electrode material recycling method of the present invention will be described in detail below with reference to specific embodiments.

[0036] Example 1

[0037] A method for recovering nickel-cobalt-manganese-lithium ternary positive electrode active material comprises the following steps:

[0038] (1) The scrapped lithium nickel cobalt manganese oxide positive electrode sheet (the positive electrode sheet includes the scrapped lithium nickel cobalt manganese oxide active material, PVDF binder and Super-P conductive agent) is immersed in NMP, heated at 70°C for 1 hour to dissolve the binder PVDF in the positive electrode sheet in NMP, filtered, and then dried at 110°C to obtain a waste material containing lithium nickel cobalt manganese oxide and the conductive agent;

[0039] (2) LiNO3 and LiOH eutectic lithium salts with a molar ratio of 3:2 were added to the waste material, mixed evenly, and sintered at 300°C in a sintering furnace for 3 hours to replenish lithium, and then calcined at 850°C for 4 hours to obtain nickel cobalt manganese oxide active material.

[0040] The repaired lithium nickel cobalt manganese oxide active material was tested for its first discharge specific capacity and first charge and discharge efficiency in accordance with the "GB / T 37201-2018 Test method for first discharge specific capacity and first charge and discharge efficiency of lithium nickel cobalt manganese oxide electrochemical performance test". Its first discharge specific capacity was 152mAh / g (0.5C discharge rate), the first charge and discharge efficiency was 85%, and the recovery rate was over 97%.

[0041] Example 2

[0042] A method for recovering lithium manganate positive electrode active material comprises the following steps:

[0043] (1) The scrapped lithium manganese oxide positive electrode sheet (the positive electrode sheet includes the scrapped lithium manganese oxide active material, PVDF binder and acetylene black conductive agent) is immersed in NMP, heated at 70°C for 1 hour to dissolve the binder PVDF in the positive electrode sheet in NMP, filtered, and then dried at 110°C to obtain a waste material containing lithium manganese oxide and the conductive agent;

[0044] (2) LiNO3 and LiOH eutectic lithium salts with a molar ratio of 1:1 are added to the waste material, mixed evenly, and sintered at 280°C in a sintering furnace for 4 hours to replenish lithium and then calcined at 850°C for 4 hours to obtain lithium manganate active material.

[0045] The repaired lithium manganate active material was subjected to the first discharge specific capacity and first charge-discharge efficiency tests in the same manner as in Example 1. The first discharge specific capacity was 102 mAh / g (0.1 C discharge rate), the first charge-discharge efficiency was 84%, and the recovery rate was 97%.

[0046] Comparative Example 1

[0047] A method for recovering nickel-cobalt-manganese-lithium ternary positive electrode active material comprises the following steps:

[0048] A. The scrapped lithium nickel cobalt manganese oxide positive electrode sheet (the positive electrode sheet includes the scrapped lithium nickel cobalt manganese oxide active material, PVDF binder and Super-P conductive agent) is immersed in NMP, heated at 70°C for 1 hour to dissolve the binder PVDF in the positive electrode sheet in the NMP, filtered, and then dried at 110°C to obtain a waste material containing lithium nickel cobalt manganese oxide and the conductive agent;

[0049] B. The waste material is placed in a high-pressure reactor, and 4 mol / L LiNO3 and 5 mol / L LiOH are added, with the total amount of LiNO3 and LiOH to the waste material ratio being 1:0.1. After mixing, the mixture is hydrothermally reacted at a pressure of 2 and a temperature of 800°C for 11 hours to obtain an intermediate product;

[0050] C. The intermediate product is washed and dried, and then calcined at 750° C. for 5 h to obtain lithium nickel cobalt manganese oxide active material.

[0051] The repaired lithium nickel cobalt manganese oxide active material was tested for its first discharge capacity and first charge-discharge efficiency in the same manner as in Example 1. The first discharge capacity was 145 mAh / g (0.5 C discharge rate), the first charge-discharge efficiency was 83%, and the recovery rate was 94%.

[0052] A comparison of Example 1 and Comparative Example 1 demonstrates that the present invention's recovery method is applicable to the recovery of a wide range of positive electrode active materials, and the recovered positive electrode active materials exhibit both high initial discharge specific capacity and initial discharge efficiency. Compared to Comparative Example 1, the present invention's recovery method achieves a higher recovery rate. This is because the solid-phase method yields the positive electrode active material through a single-step sintering step, while Comparative Example 1 employs a hydrothermal method that requires the preparation of an intermediate product followed by cleaning and calcination, resulting in multiple steps that reduce the recovery rate.

[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 scope of protection of the present invention. Although the present invention is described in detail with reference to the preferred embodiments, it is not limited to those listed in the embodiments. Those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A recycling device for lithium-ion battery positive electrode active materials, characterized in that: The invention comprises a recovery tank for dissolving the binder in the positive electrode sheet and recovering the positive electrode waste material, a first conveying mechanism for conveying the positive electrode waste material, a powder mixing tank for mixing the positive electrode waste material with LiNO3 and LiOH eutectic lithium salt, a second conveying mechanism for conveying the mixed powder, and a sintering furnace for solid-phase reaction and sintering the powder, wherein the upper two sides of the powder mixing tank are respectively provided with a positive electrode waste material feeding port and a eutectic lithium salt feeding port connected to the first conveying mechanism, a discharge pipe is provided at the lower part of the powder mixing tank, and the powder mixing tank is provided with a discharge pipe. The bottom wall of the inner cavity of the combined tank is an arc-shaped structure and the bottom end extends to the discharge pipe. A vent is provided on the wall of the discharge pipe. A valve for controlling the opening or closing of the discharge pipe is provided inside the discharge pipe. A positive electrode sheet feed port and an NMP feed port are provided on both sides of the upper part of the recovery tank, respectively. The interior of the recovery tank is provided with a first screen for intercepting the positive electrode current collector and a second screen for intercepting the positive electrode waste material from top to bottom. The recovery tank is provided with an NMP discharge port below the second screen. The recovery tank is also provided with a heating mechanism for heating NMP and a discharge port connected to the first conveying mechanism.

2. The recycling equipment for lithium-ion battery positive electrode active materials according to claim 1, characterized in that: The bottom surface of the discharge port and the second screen are located at the same horizontal plane, and the first conveying mechanism includes a conveyor belt and a transport tray that moves with the conveyor belt and matches the height of the discharge port.

3. The recycling equipment for lithium-ion battery positive electrode active materials according to claim 1, characterized in that: The second conveying mechanism is located below the discharge pipe, and includes a conveying belt and a sagger that moves with the conveying belt and is located below the discharge pipe.

4. A method for recovering positive electrode active materials of lithium ion batteries using the recovery equipment for positive electrode active materials of lithium ion batteries according to any one of claims 1 to 3, characterized in that: Including steps: (1) Soaking the scrapped positive electrode sheet in NMP, heating to dissolve the binder in the positive electrode sheet in the NMP, filtering and drying to obtain the positive electrode waste material; (2) LiNO3 and LiOH eutectic lithium salts are added to the positive electrode waste material, mixed evenly, and then lithium supplemented and repaired by a solid phase method, followed by high-temperature sintering.

5. The method for recovering positive electrode active materials of lithium ion batteries according to claim 4, characterized in that: The drying temperature in the step (1) is higher than the heating temperature.

6. The method for recovering positive electrode active materials of lithium ion batteries according to claim 4, characterized in that: The molar ratio of the LiNO3 to the LiOH is 2 to 4:

2.

7. The method for recovering positive electrode active materials of lithium ion batteries according to claim 4, characterized in that: The reaction temperature of the solid phase method is 260-350° C., the reaction time is 2-4 hours, and the sintering temperature is 750-950° C., the time is 3-5 hours.

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