Method for repairing and recycling positive electrode powder of lithium iron phosphate battery

Abstract

The invention discloses a lithium iron phosphate battery positive powder repairing and recycling method which comprises the following steps: S1, disassembling a pretreated lithium iron phosphate battery to obtain a positive plate, and carrying out powder removal treatment on the positive plate to obtain an aluminum foil and positive powder; s2, performing impurity removal and oxidation treatment on the positive electrode powder to remove impurities such as a binder, conductive carbon black and coated carbon in the positive electrode powder to obtain oxidized positive electrode powder, and condensing the oxidized positive electrode powder together to form a positive electrode powder block; and S3, grinding the positive electrode powder block into powder through a grinding mechanism, and adding auxiliary materials in the grinding process to obtain mixed powder. According to the method, the positive electrode powder is recycled in a repairing manner, so that the utilization rate of the positive electrode powder is improved to a great extent, the mining demand on primary mineral resources is greatly reduced, and a stable and low-cost positive electrode material supply channel is provided for lithium batteries and related industries.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery cathode powder repair and reuse. Specifically, it relates to a method for repairing and reusing lithium iron phosphate battery cathode powder. Background Art

[0002] With the booming development of the new energy vehicle industry, the demand for power lithium batteries continues to climb, leading to a sharp increase in the number of waste batteries. If the cathode materials such as iron-lithium powder contained in these waste batteries are not properly recycled, it is not only a huge waste of precious resources but also may cause serious environmental pollution. Therefore, the recycling of lithium iron phosphate battery cathode powder becomes particularly important;

[0003] In the prior art, the recycling of lithium battery cathode powder mainly includes pretreatment methods, pyrometallurgy, and hydrometallurgical leaching, etc. The pretreatment recycling process includes steps such as removing impurities (such as metal oxides, carbon black, etc.), and preliminarily crushing and grinding battery materials; pyrometallurgy recovers metals in waste lithium iron phosphate cathode powder through high-temperature smelting. However, this method has high energy consumption and is prone to environmental pollution, so it is limited in practical applications; in the hydrometallurgical leaching process, chemical solvents such as strong acids, strong alkalis, and a large amount of ammonia water are required. If these solvents are not properly treated, they may cause new pollution to the environment. At the same time, the hydrometallurgical process is complex, and the applicability to raw materials is limited, especially the reuse of lithium iron phosphate is very limited.

[0004] Therefore, to solve the above problems, this paper proposes a method for repairing and reusing lithium iron phosphate battery cathode powder, which is of great significance for improving the reuse of lithium iron phosphate. Summary of the Invention

[0005] The present invention proposes a method for repairing and reusing lithium iron phosphate battery cathode powder, which can efficiently and completely separate the cathode sheet of a waste LFP battery from the current collector, and at the same time, no pollutants such as dust and waste gas will be generated.

[0006] The technical solution of the present invention is realized as follows:

[0007] A method for repairing and reusing lithium iron phosphate battery cathode powder, comprising:

[0008] S1, disassembling the pretreated lithium iron phosphate battery to obtain a cathode sheet, and performing deflaking treatment on the cathode sheet to obtain aluminum foil and cathode powder;

[0009] S2, performing impurity removal and oxidation treatment on the cathode powder to remove impurities such as binder, conductive carbon black, and coated carbon in the cathode powder to obtain oxidized cathode powder, and the oxidized cathode powder will coagulate together to form a cathode powder block;

[0010] S3, grinding the cathode powder block into powder by a grinding mechanism, and adding auxiliary materials during the grinding process to obtain a mixed powder;

[0011] S4. Perform high-temperature repair treatment on the mixed powder materials to obtain the precursor LiFePO4 / C of the recyclable battery-grade lithium iron phosphate material.

[0012] Preferably, in step S1, it includes: using battery disassembly equipment to disassemble the lithium iron phosphate battery into a shell, a separator, and positive and negative electrode sheets; classifying and storing the shell, the separator, and the negative electrode sheet, and using the positive electrode sheet as a raw material for processing; separating the positive electrode powder from the aluminum foil through a soaking or ultrasonic treatment process for the positive electrode sheet; after the treatment, the positive electrode powder and the aluminum foil fall into the water, and the aluminum foil can be taken out completely; most of the positive electrode powder scattered in the water is in irregular sheet shapes, and it can be taken out of the water by filtration; during the above process, if large pieces of positive electrode sheets are difficult to handle, they can be broken into smaller pieces for treatment.

[0013] Preferably, the process of powder removal treatment in step S1 includes: soaking and ultrasonically treating the positive electrode sheet, with the soaking time being 0.5 - 3 min and the ultrasonic treatment time being 0.5 - 1 min; using a stirring device equipped with the ultrasonic equipment to perform stirring and ultrasonic treatment simultaneously, stirring while ultrasonicating to better dissociate the positive electrode powder and the aluminum foil. After dissociation, the positive electrode powder will fall into the positive electrode powder collection bin through the aluminum foil filter screen of the ultrasonic equipment and be intercepted by the screen at the bottom of the positive electrode powder collection bin at the same time; after the ultrasonic treatment ends, the positive electrode powder collection bin and the screen are removed from the ultrasonic equipment to complete the separation of the positive electrode powder, the aluminum foil, and the water.

[0014] Preferably, step S2 includes: placing the positive electrode powder obtained from the powder removal treatment in a high-temperature oxidation furnace and performing high-temperature impurity removal and oxidation treatment in an air atmosphere, with the impurity removal and oxidation temperature being 500 - 600 °C and the heating time being 2 - 4 h.

[0015] Preferably, the high-temperature oxidation furnace can be a rotary high-temperature oxidation furnace.

[0016] Preferably, step S3 includes: using a ball mill to process the positive electrode powder block, adding auxiliary materials at the same time, and grinding for 4 h to make the positive electrode powder block and the auxiliary materials evenly mixed; after grinding, obtaining the mixed powder; performing sieving treatment on the mixed powder materials, with the sieve mesh aperture being 20 - 30 μm, and taking the materials passing through the sieve for subsequent repair treatment.

[0017] Preferably, the auxiliary materials are made of raw materials with the following mass fraction ratios: 3% - 7% of a lithium source, 3% - 7% of a phosphorus source, and 3% - 7% of a reducing agent.

[0018] Preferably, the lithium source is lithium carbonate, the phosphorus source is ammonium dihydrogen phosphate, and the reducing agent is sucrose.

[0019] Preferably, step S3 includes:

[0020] After mixing and dispersing the sieved undersize material and absolute ethanol in a ratio of 1:0.5 and stirring for 2h - 4h, place it in an oven for drying. The drying temperature is 60°C - 90°C, and the drying time is 3h - 6h. At the same time, during the grinding process, avoid excessive dust and impurities from entering the mixed material.

[0021] Preferably, the step S4 includes: placing the dried cathode powder in a sintering furnace, under the protection of a nitrogen atmosphere, heating from room temperature to 200°C - 350°C at a temperature rise rate of 5°C / min, and holding for 4h - 6h; then heating from 200°C - 350°C to 650°C - 800°C at a temperature rise rate of 5°C / min, and holding for 8h - 10h; after the heating and holding process ends, naturally cool to obtain the regenerated lithium iron phosphate material.

[0022] Beneficial effects:

[0023] The present invention can efficiently and completely separate the cathode sheet of the waste LFP battery from the current collector, and at the same time, no pollutants such as dust and waste gas will be generated. The present invention uses a repair method to recycle the cathode powder, greatly improving the utilization rate of the cathode powder, significantly reducing the demand for the exploitation of primary mineral resources, and providing a stable and low-cost supply channel of cathode materials for the lithium battery and related industries. Compared with pyrometallurgy and hydrometallurgical leaching, the present invention has low energy consumption, does not involve complex chemical processes, and at the same time recovers valuable metals in the form of battery powder precursors, reducing the cost of recycling valuable metals. Description of the drawings

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0025] Figure 1 is a process flow chart of a method for repairing and recycling the cathode powder of a lithium iron phosphate battery according to an embodiment of the present invention;

[0026] Figure 2 is a structural schematic diagram of a method for repairing and recycling the cathode powder of a lithium iron phosphate battery according to an embodiment of the present invention;

[0027] Figure 3 is a structural schematic diagram of an aluminum foil filter screen in a method for repairing and recycling the cathode powder of a lithium iron phosphate battery according to an embodiment of the present invention;

[0028] Figure 4 is a structural schematic diagram of a cathode powder filter screen in a method for repairing and recycling the cathode powder of a lithium iron phosphate battery according to an embodiment of the present invention.

[0029] In the figure, 1 is a stirring device; 2 is an aluminum foil filter screen; 3 is the collection point of the positive electrode powder; 4 is the positive electrode powder filter screen. Specific embodiments

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present invention.

[0031] According to an embodiment of the present invention, a method for repairing and recycling the positive electrode powder of a lithium iron phosphate battery is provided.

[0032] As Figure 1 - Figure 2 shown, in this alternative embodiment, the method for repairing and recycling the positive electrode powder of a lithium iron phosphate battery according to the embodiment of the present invention includes:

[0033] S1. Disassemble the pre-treated lithium iron phosphate battery to obtain a positive electrode sheet, and perform deflaking treatment on the positive electrode sheet to obtain aluminum foil and positive electrode powder;

[0034] S2. Perform impurity removal and oxidation treatment on the positive electrode powder to remove impurities such as binders, conductive carbon black, and coated carbon in the positive electrode powder, and obtain oxidized positive electrode powder. The oxidized positive electrode powder will coagulate together to form a positive electrode powder block;

[0035] S3. Grind the positive electrode powder block into powder by a grinding mechanism, and add auxiliary materials during the grinding process to obtain a mixed powder;

[0036] S4. Perform high-temperature repair treatment on the mixed powder to obtain a precursor LiFePO4 / C of battery-grade lithium iron phosphate material that can be recycled.

[0037] In this alternative embodiment,

[0038] The step S1 includes: using battery disassembly equipment to disassemble the lithium iron phosphate battery into a casing, a separator, and positive and negative electrode sheets; storing the casing, the separator, and the negative electrode sheet separately, and using the positive electrode sheet as a raw material for processing; separating the positive electrode powder from the aluminum foil by soaking in water or ultrasonic treatment on the positive electrode sheet; after treatment, the positive electrode powder and the aluminum foil are scattered in water, and the aluminum foil can be taken out completely; most of the positive electrode powder scattered in water is in irregular sheet shape, and it can be taken out of the water by filtration;

[0039] In the above process, if large positive electrode sheets are difficult to process, they can be broken into smaller sheet shapes for processing.

[0040] In this alternative embodiment, the process of powder removal treatment in step S1 includes: soaking the positive electrode sheet in water and performing ultrasonic treatment. The soaking time is 0.5 - 3 min, and the ultrasonic treatment time is 0.5 - 1 min; a stirring device 1 is equipped in the ultrasonic device to work synchronously for stirring and ultrasonic treatment, stirring while performing ultrasonic treatment to better dissociate the positive electrode powder and the aluminum foil. After dissociation, the positive electrode powder will fall into the positive electrode powder collection bin 3 through the aluminum foil filter screen 2 of the ultrasonic device, and at the same time, it will be intercepted by the screen 4 at the bottom of the positive electrode powder collection bin; after the ultrasonic treatment ends, the positive electrode powder collection bin 3 and the screen 2 are removed from the ultrasonic device to complete the separation of the positive electrode powder, the aluminum foil, and water.

[0041] In this alternative embodiment, step S2 includes: placing the positive electrode powder obtained from the powder removal treatment in a high-temperature oxidation furnace and performing high-temperature impurity removal and oxidation treatment in an air atmosphere. The impurity removal and oxidation temperature is 500 - 600 °C, and the heating time is 2 - 4 h.

[0042] In this alternative embodiment, the high-temperature oxidation furnace can be a rotary high-temperature oxidation furnace.

[0043] In this alternative embodiment, step S3 includes: using a ball mill to process the positive electrode powder block, and at the same time adding auxiliary materials and grinding for 4 h to make the positive electrode powder block and the auxiliary materials evenly mixed; after grinding, the obtained mixed powder; performing sieving treatment on the mixed powder. The aperture of the sieve is 20 - 30 μm, and the materials passing through the sieve are taken for subsequent repair treatment.

[0044] In this alternative embodiment, the auxiliary materials are made of raw materials with the following mass fraction ratios:

[0045] 3% - 7% lithium source, 3% - 7% phosphorus source, 3% - 7% reducing agent.

[0046] In this alternative embodiment, the lithium source is lithium carbonate, the phosphorus source is ammonium dihydrogen phosphate, and the reducing agent is sucrose.

[0047] In this alternative embodiment, step S3 includes: mixing and dispersing the materials passing through the sieve and absolute ethanol in a ratio of 1:0.5 and stirring for 2 - 4 h, then placing them in an oven for drying treatment. The drying temperature is 60 °C - 90 °C, and the drying time is 3 h - 6 h. At the same time, during the grinding process, excessive dust and impurities are avoided from entering the mixed materials.

[0048] In this alternative embodiment, step S4 includes: placing the dried positive electrode powder in a sintering furnace, under the protection of a nitrogen atmosphere, heating from room temperature to 200 °C - 350 °C at a temperature rise rate of 5 °C / min and holding for 4 h - 6 h; then heating from 200 °C - 350 °C to 650 °C - 800 °C at a temperature rise rate of 5 °C / min and holding for 8 h - 10 h; after the heating and holding process ends, the regenerated lithium iron phosphate material is obtained after natural cooling.

[0049] To facilitate the understanding of the above technical solution of the present invention, the following further illustrates the above technical solution of the present invention through multiple specific embodiments.

[0050] Example 1

[0051] Precisely disassemble 10 used LFP batteries to obtain the positive electrode sheets. In this process, the outer shell, separator, and positive and negative electrode sheets can be completely separated;

[0052] Place the positive electrode sheets in an ultrasonic instrument for powder removal treatment. The positive electrode sheets stay in the ultrasonic device for 0.5 minutes. Under the action of ultrasonic waves, the positive electrode powder will fall off the aluminum foil in the form of flakes. Under the action of the stirring device, it is dispersed into smaller flakes and enters the positive electrode powder collection area through the aluminum foil filter screen. Most of the positive electrode powder is intercepted on the filter screen through the interception of the positive electrode powder filter screen. When a batch of positive electrode sheets is processed, the aluminum foil and positive electrode sheets on the aluminum foil filter screen and the positive electrode powder filter screen can be taken out.

[0053] The filtered positive electrode powder is placed in a high-temperature oxidation furnace for drying treatment and high-temperature impurity removal and oxidation treatment at the same time. The high-temperature impurity removal and oxidation treatment are carried out in an air atmosphere. To make the impurity removal and oxidation effect uniform, a rotary high-temperature oxidation furnace is used. The impurity removal and oxidation temperature is 500 °C, and the heating time is 2 h;

[0054] The positive electrode powder after impurity removal and oxidation is processed using a ball mill. According to the component test results, 16% lithium carbonate (based on the lithium element content), 16% ammonium dihydrogen phosphate (based on the phosphorus element content), and 20 mass% sucrose (the mass fraction of sucrose is 9%) are added and ground together for 4 h to make the positive electrode powder and the later-added materials evenly mixed. After grinding, the powder material is sieved. The sieve mesh aperture is 30 μm, and the material under the sieve is taken for subsequent repair treatment;

[0055] The material under the sieve after sieving is mixed and dispersed with absolute ethanol in a ratio of 1:0.5 and stirred for 2 h, and then placed in an oven for drying treatment. The drying temperature is 85 °C, and the drying time is 5 h. At the same time, during the grinding process, pay attention to the cleanliness of the surrounding environment to avoid excessive dust and impurities from entering the mixed material;

[0056] Place the dried positive electrode powder in a sintering furnace. Under the protection of an inert gas, it is heated from room temperature to 300 °C at a temperature rise rate of 5 °C / min and kept warm for 5 h; then it is heated from 300 °C to 650 °C at a temperature rise rate of 5 °C / min and kept warm for 8 h respectively. After the heating and insulation process is completed, the regenerated lithium iron phosphate material is obtained after natural cooling.

[0057] Example 2

[0058] Precisely disassemble 10 used LFP batteries to obtain the positive electrode sheets. In this process, the outer shell, separator, and positive and negative electrode sheets can be completely separated;

[0059] Place the positive electrode sheet in an ultrasonic instrument for powder removal treatment. The positive electrode sheet stays in the ultrasonic device for 1 minute. Under the action of ultrasonic waves, the positive electrode powder will fall off from the aluminum foil in the form of flakes. Under the action of the stirring device, it will be dispersed into smaller flakes and enter the positive electrode powder collection area through the aluminum foil filter screen. Most of the positive electrode powder will be intercepted on the filter screen through the interception of the positive electrode powder filter screen. When a batch of positive electrode sheets is processed, the aluminum foil and positive electrode sheets on the aluminum foil filter screen and the positive electrode powder filter screen can be taken out;

[0060] The filtered positive electrode powder is placed in a high-temperature oxidation furnace for drying treatment and high-temperature impurity removal and oxidation treatment at the same time. The high-temperature impurity removal and oxidation treatment is carried out in an air atmosphere. In order to make the impurity removal and oxidation effect uniform, a rotary high-temperature oxidation furnace is used; the impurity removal and oxidation temperature is 500 °C, and the heating time is 4 h;

[0061] The positive electrode powder after impurity removal and oxidation is processed by a ball mill. According to the component test results, 16% lithium carbonate (based on the lithium element content), 16% ammonium dihydrogen phosphate (based on the phosphorus element content), and 20 mass% sucrose (the mass fraction of sucrose is 9%) are added and ground together for 4 h to make the positive electrode powder and the later added materials evenly mixed. After grinding, the powder material is sieved. The aperture of the sieve mesh is 30 μm, and the material under the sieve is taken for subsequent repair treatment;

[0062] The material under the sieve after sieving is mixed and dispersed with absolute ethanol in a ratio of 1:0.5 and stirred for 2 h, and then placed in an oven for drying treatment. The drying temperature is 85 °C, and the drying time is 5 h. At the same time, during the grinding process, pay attention to the cleanliness of the surrounding environment to avoid excessive dust and impurities from entering the mixed material;

[0063] Place the dried positive electrode powder in a sintering furnace. Under the protection of an inert gas, it is heated from room temperature to 300 °C at a temperature rise rate of 5 °C / min and kept warm for 5 h; then it is heated from 300 °C to 650 °C at a temperature rise rate of 5 °C / min and kept warm for 10 h. After the heating and insulation process is completed, the regenerated lithium iron phosphate material is obtained after natural cooling.

[0064] Example three

[0065] Precisely disassemble 10 used LFP batteries to obtain positive electrode sheets. In this process, the outer shell, separator, and positive and negative electrode sheets can be completely separated;

[0066] Place the positive electrode sheet in a soaking tank for powder removal treatment. The positive electrode sheet stays in the soaking tank for 2 minutes. Under the action of the stirring device, the positive electrode powder will fall off from the aluminum foil in the form of flakes and at the same time be dispersed into smaller flakes and enter the positive electrode powder collection area through the aluminum foil filter screen. Most of the positive electrode powder will be intercepted on the filter screen through the interception of the positive electrode powder filter screen. When a batch of positive electrode sheets is processed, the aluminum foil and positive electrode sheets on the aluminum foil filter screen and the positive electrode powder filter screen can be taken out;

[0067] The filtered positive electrode powder is placed in a high-temperature oxidation furnace for drying treatment while undergoing high-temperature impurity removal and oxidation treatment. The high-temperature impurity removal and oxidation treatment is carried out in an air atmosphere. To ensure uniform impurity removal and oxidation effect, a rotary high-temperature oxidation furnace is used. The impurity removal and oxidation temperature is 500 °C, and the heating time is 3 h.

[0068] The positive electrode powder after impurity removal and oxidation is processed using a ball mill. According to the component test results, 16% lithium carbonate (based on the lithium element content), 16% ammonium dihydrogen phosphate (based on the phosphorus element content), and 20 mass% sucrose (the mass fraction of sucrose is 9%) are added and ground together for 4 h to make the positive electrode powder and the subsequently added materials evenly mixed. After grinding, the powder material is sieved. The sieve mesh aperture is 30 μm, and the material passing through the sieve is taken for subsequent repair treatment.

[0069] The material passing through the sieve after sieving is mixed and dispersed with absolute ethanol at a ratio of 1:0.5 and stirred for 2 h, and then placed in an oven for drying treatment. The drying temperature is 85 °C, and the drying time is 5 h. At the same time, during the grinding process, attention should be paid to the cleanliness of the surrounding environment to avoid excessive dust and impurities from entering the mixed material.

[0070] The dried positive electrode powder is placed in a sintering furnace. Under the protection of an inert gas, it is heated from room temperature to 300 °C at a temperature rise rate of 5 °C / min and held for 5 h; then it is heated from 300 °C to 750 °C at a temperature rise rate of 5 °C / min and held for 8 h respectively. After the heating and holding process is completed, the regenerated lithium iron phosphate material is obtained after natural cooling.

[0071] Example 4

[0072] Ten used LFP batteries are precisely disassembled to obtain the positive electrode plates. In this process, the outer shell, separator, and positive and negative electrode plates can be completely separated.

[0073] The positive electrode plates are placed in a soaking tank for powder removal treatment. The positive electrode plates stay in the soaking tank for 3 minutes. Under the action of the stirring device, the positive electrode powder will fall off from the aluminum foil in the form of flakes and at the same time be dispersed into smaller flakes, enter the positive electrode powder collection area through the aluminum foil filter screen, and most of the positive electrode powder is intercepted on the filter screen by the interception of the positive electrode powder filter screen. When a batch of positive electrode plates is processed, the aluminum foil and positive electrode plates on the aluminum foil filter screen and the positive electrode powder filter screen can be taken out.

[0074] The filtered positive electrode powder is placed in a high-temperature oxidation furnace for drying treatment while undergoing high-temperature impurity removal and oxidation treatment. The high-temperature impurity removal and oxidation treatment is carried out in an air atmosphere. To ensure uniform impurity removal and oxidation effect, a rotary high-temperature oxidation furnace is used. The impurity removal and oxidation temperature is 500 °C, and the heating time is 3 h.

[0075] The post-removal and oxidation cathode powder is processed using a ball mill. According to the component test results, 16% lithium carbonate (based on the lithium element content), 16% ammonium dihydrogen phosphate (based on the phosphorus element content), and 20 mass% sucrose (the mass fraction of sucrose is 9%) are added, and they are ground together for 4 h to evenly mix the cathode powder with the subsequently added materials. After grinding, the powder material is sieved. The aperture of the sieve mesh is 30 μm, and the undersize material is taken for subsequent repair treatment;

[0076] The undersize material after sieving is mixed and dispersed with absolute ethanol at a ratio of 1:0.5 and stirred for 2 h, and then placed in an oven for drying treatment. The drying temperature is 85 °C, and the drying time is 5 h. At the same time, during the grinding process, pay attention to the cleanliness of the surrounding environment to avoid excessive dust and impurities from entering the mixed material;

[0077] The dried cathode powder is placed in a sintering furnace. Under the protection of an inert gas, it is heated from room temperature to 300 °C at a temperature rise rate of 5 °C / min and held for 5 h; then it is heated from 300 °C to 750 °C at a temperature rise rate of 5 °C / min and held for 10 h respectively. After the heating and holding process ends, the regenerated lithium iron phosphate material is obtained after natural cooling.

[0078] The comparison table of the ultrasonic powder removal method and the soaking powder removal method embodiments is shown in the following table:

[0079]

[0080] It can be seen from the above table that different powder removal methods have little effect on the morphology of the regenerated cathode powder. In the powder removal link, the key point is to avoid excessive aluminum foil from entering the cathode powder; for the impurity removal and oxidation stage, when the impurity removal temperature is high enough, increasing the impurity removal time has little effect on the regenerated cathode powder; the state of the regenerated cathode powder is greatly affected by the treatment temperature and time in the repair and regeneration stage.

[0081] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for repairing and reusing positive electrode powder of lithium iron phosphate battery, characterized in that: include: S1, disassembling the pretreated lithium iron phosphate battery to obtain a positive electrode sheet, and performing a de-powdering treatment on the positive electrode sheet to obtain an aluminum foil and a positive electrode powder; S2, performing impurity removal and oxidation treatment on the positive electrode powder to remove impurities such as a binder, conductive carbon black, and coated carbon in the positive electrode powder to obtain oxidized positive electrode powder, which will condense together to form a positive electrode powder block; S3, grinding the positive electrode powder block into powder by a grinding mechanism, adding auxiliary materials during the grinding process, and obtaining a mixed powder after the grinding is completed; S4, subjecting the mixed powder to high-temperature repair treatment to obtain LiFePO4 / C, a precursor of a recyclable battery-grade lithium iron phosphate material.

2. The method for repairing and reusing positive electrode powder of a lithium iron phosphate battery according to claim 1, characterized in that: The step S1 comprises: Use battery disassembly equipment to disassemble the lithium iron phosphate battery into the casing, diaphragm and positive and negative electrodes; The casing, separator and negative electrode sheets are stored separately, and the positive electrode sheets are processed as raw materials; The positive electrode sheet is soaked in water or ultrasonically treated to separate the positive electrode powder from the aluminum foil; The treated positive electrode powder and aluminum foil are scattered in the water, and the aluminum foil can be taken out intact; The positive electrode powder scattered in the water is mostly in irregular flakes and can be removed from the water by filtering; In the above process, if a large piece of positive electrode is difficult to handle, it can be broken into smaller pieces for processing.

3. A method for repairing and reusing positive electrode powder of a lithium iron phosphate battery according to claim 2, characterized in that: The de-powdering process in step S1 includes: Soak the positive electrode in water or perform ultrasonic treatment, the soaking time is 0.5-3 minutes, and the ultrasonic treatment time is 0.5-1 minute; The ultrasonic device is equipped with a stirring device (1) to perform stirring and ultrasonication simultaneously, stirring and ultrasonication at the same time, so that the positive electrode powder and the aluminum foil are better dissociated. The dissociated positive electrode powder passes through the aluminum foil filter (2) of the ultrasonic device and falls into the positive electrode powder collection bin (3), and is intercepted by the screen (4) at the bottom of the positive electrode powder collection bin; After the ultrasound treatment is completed, the positive electrode powder collection bin (3) and the screen (2) are removed from the ultrasound device to complete the separation of the positive electrode powder, the aluminum foil and the water.

4. The method for repairing and reusing positive electrode powder of a lithium iron phosphate battery according to claim 1, characterized in that: The step S2 comprises: The positive electrode powder obtained by the de-powdering treatment is placed in a high-temperature oxidation furnace and subjected to high-temperature impurity removal and oxidation treatment in an air atmosphere. The impurity removal and oxidation temperature is 500-600° C. and the heating time is 2-4 hours.

5. A method for repairing and reusing positive electrode powder of a lithium iron phosphate battery according to claim 4, characterized in that: The high temperature oxidation furnace can be a rotary high temperature oxidation furnace.

6. The method for repairing and reusing positive electrode powder of a lithium iron phosphate battery according to claim 1, characterized in that: The step S3 comprises: Use a ball mill to process the positive electrode powder block, add auxiliary materials at the same time, and grind for 4 hours to make the positive electrode powder block and auxiliary materials evenly mixed; After grinding, the obtained mixed powder; The mixed powder is sieved with a sieve aperture of 20-30 μm, and the material under the sieve is taken for subsequent repair treatment.

7. A method for repairing and reusing positive electrode powder of a lithium iron phosphate battery according to claim 6, characterized in that: The auxiliary materials are made of the following raw materials in mass fraction ratio: 3%-7% lithium source, 3%-7% phosphorus source, 3%-7% reducing agent.

8. The method for repairing and reusing positive electrode powder of a lithium iron phosphate battery according to claim 7, characterized in that: The lithium source is lithium carbonate, the phosphorus source is ammonium dihydrogen phosphate, and the reducing agent is sucrose.

9. The method for repairing and reusing positive electrode powder of a lithium iron phosphate battery according to claim 6, characterized in that: The step S3 comprises: The sieved material is mixed with anhydrous ethanol in a ratio of 1:0.5 and dispersed and stirred for 2h-4h, and then placed in an oven for drying at a temperature of 60℃-90℃ and a drying time of 3h-6h. At the same time, during the grinding process, avoid excessive dust and impurities from entering the mixed material.

10. The method for repairing and reusing positive electrode powder of a lithium iron phosphate battery according to claim 1, characterized in that: The step S4 comprises: The dried positive electrode powder is placed in a sintering furnace, and under the protection of a nitrogen atmosphere, the temperature is raised from room temperature to 200°C-350°C at a temperature rise rate of 5°C / min, and the temperature is kept for 4h-6h; Then increase the temperature from 200℃-350℃ to 650℃-800℃ at a temperature rise rate of 5℃ / min, and keep it at this temperature for 8h-10h; After the heating and heat preservation process is completed, the regenerated lithium iron phosphate material is obtained after natural cooling.

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