Method for regenerating lithium iron phosphate positive electrode material with assistance of negative electrode lithium and waste diaphragm

Abstract

The invention discloses a method for regenerating a lithium iron phosphate positive electrode material with assistance of negative electrode lithium and a waste diaphragm. The method comprises the following steps: pretreating a waste lithium iron phosphate battery to obtain a waste lithium iron phosphate positive electrode plate, a waste diaphragm and a negative electrode plate; extracting residual lithium in the negative electrode by using a water immersion method, and uniformly mixing the recycled lithium with the waste positive electrode powder and the waste diaphragm; putting into a tubular furnace, introducing protective gas for thermal repair, and cooling to obtain a regenerated lithium iron phosphate positive electrode material; according to the method, residual lithium in a negative electrode serves as a lithium source, a diaphragm contained in the battery serves as a reducing agent and a carbon source at the same time, the waste lithium iron phosphate battery positive electrode material is directly repaired through mixed high-temperature roasting, and the obtained lithium iron phosphate positive electrode material has good electrochemical performance. No additional reagent is needed, and a brand-new thought is provided for regeneration of the lithium iron phosphate.

Description

Technical Field

[0001] The invention relates to a waste battery repair technology, and in particular to a method for regenerating a lithium iron phosphate positive electrode material with the assistance of negative electrode lithium and waste diaphragms. Background Art

[0002] Since its birth, lithium-ion batteries have been widely used in energy storage, mobile communications and other fields. In recent years, the rapid development of the new energy industry has promoted the further expansion of the lithium-ion battery market. Among the various commercial lithium-ion batteries (LCO, NMC, LFP, etc.), lithium iron phosphate batteries (LFP) have gradually occupied more and more market share due to their advantages such as high operating voltage, high energy density, long cycle life, good safety performance, low self-discharge rate, and no memory effect. It should be noted that the service life of lithium-ion batteries is generally 3 to 8 years. It can be foreseen that the peak period of retirement of waste lithium-ion batteries will occur in the next few years. In the future, there will also be a huge amount of waste lithium-ion batteries. Therefore, it is crucial to properly handle waste lithium-ion batteries.

[0003] The positive electrode of waste lithium-ion batteries contains a variety of valuable metals and components, and has a very high recycling value. At present, the most commonly used recycling methods include pyrometallurgy, hydrometallurgy and direct regeneration. Among them, direct regeneration is widely used because of its advantages such as short process, environmental friendliness, simple operation and high economic benefits. For the positive electrode of waste lithium iron phosphate batteries, the capacity decrease of LFP positive electrode materials is caused by lithium ion loss, active mass loss and collector corrosion. The main reasons are the loss of Li and Fe occupying Li sites to form FeLi anti-site defects. Therefore, in the existing direct regeneration process, it is necessary to add additional lithium sources and reducing agents, and then regenerate by hydrothermal method or high-temperature sintering method. In addition, in order to further improve the electrochemical properties of the positive electrode material, additional carbon sources are often added.

[0004] During the use of waste lithium-ion batteries, lithium ions will continuously escape and embed between the positive and negative electrodes, which results in a certain amount of active lithium in the negative electrode after the battery capacity decreases. Compared with the precious metal components contained in the positive electrode, the recycling of the negative electrode is relatively meaningless. Therefore, in previous studies, there has been relatively little research on the negative electrode, which has led to the waste of active lithium resources in the negative electrode. In recent years, with the rapid expansion of the lithium-ion battery market, the reuse of lithium resources has received more and more attention. Therefore, if the lithium resources in the negative electrode can be reused, it will alleviate the shortage of lithium resources to a certain extent.

[0005] In waste batteries, in addition to the positive and negative electrodes, the diaphragm is also an important component. The diaphragm in the battery is generally composed of polyethylene (PE) or polypropylene (PP) film. However, compared with the high-value positive electrode materials, the diaphragm is rarely studied due to its low recycling value. However, as the amount of waste diaphragms increases, the reasonable recycling and treatment of waste diaphragms can not only avoid environmental pollution, but also greatly increase the economic value of waste battery recycling. Summary of the invention

[0006] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for regenerating lithium iron phosphate positive electrode materials with the assistance of negative electrode lithium and waste diaphragms, using the active lithium contained in the negative electrode as a lithium source and the waste diaphragm as a reducing agent and a carbon source, and achieving the repair and regeneration of the waste lithium iron phosphate positive electrode without adding any external reagents.

[0007] The present invention is achieved through the following technical solutions:

[0008] A method for regenerating a lithium iron phosphate positive electrode material with the assistance of negative electrode lithium and waste diaphragm comprises the following steps:

[0009] 1) Pre-treating the waste lithium iron phosphate batteries to obtain waste lithium iron phosphate positive electrode sheets, waste diaphragms and negative electrode sheets;

[0010] 2) placing the negative electrode sheet in deionized water and separating the negative electrode material and the copper foil by ultrasound;

[0011] 3) placing the negative electrode material in deionized water and stirring to obtain a lithium-rich solution and a negative electrode graphite material;

[0012] 4) adding sodium carbonate to the lithium-containing solution obtained in step 3) and stirring at high temperature until the solution evaporates and an off-white solid appears; filtering out the white solid, rinsing it and drying it to obtain Li2CO3;

[0013] 5) calcining the waste lithium iron phosphate positive electrode sheet at high temperature in a tube furnace to remove the binder, and then grinding to obtain the waste lithium iron phosphate positive electrode powder, and determining the content of lithium, iron and phosphorus in the waste lithium iron phosphate positive electrode powder;

[0014] 6) cutting the waste diaphragm obtained in step 1) into small pieces;

[0015] 7) uniformly mixing the waste positive electrode powder obtained in step 5) and the waste diaphragm flakes obtained in step 6);

[0016] 8) The mixed material obtained in step 7) and the Li2CO3 solid obtained in step 4) are mixed evenly, and the amount of Li2CO3 solid added is determined according to the lithium-iron element ratio determined in step 5). After mixing, the mixture is placed in a tubular furnace, a protective gas is introduced, and the temperature is raised to 500°C at 5°C / min and maintained for 1 hour, and then the temperature is raised to 600-800°C at 5°C / min and maintained for 4-8 hours. After cooling, the regenerated lithium iron phosphate positive electrode material is obtained.

[0017] Preferably, in step 1), the waste lithium iron phosphate battery is immersed in a 5wt% NaCl solution and allowed to stand for 24 hours to release residual electricity; then placed in a forced air drying oven for 24 hours and manually disassembled to collect the positive electrode sheet, the separator, and the negative electrode sheet, and placed in a DMC solution to remove surface electrolyte.

[0018] Preferably, in step 2), the ultrasonic power is 100 W and the ultrasonic time is 0.5 to 1 h.

[0019] Preferably, in step 3), the negative electrode material is stirred in deionized water for 2 to 3 hours.

[0020] Preferably, in step 4), the lithium-containing solution is stirred at 90° C. until the solution evaporates and an off-white solid appears.

[0021] Preferably, the high temperature calcination temperature in step 5) is 450-550° C., and the calcination time is 1-3 hours.

[0022] Preferably, in step 5), an inductively coupled plasma emission spectrometer is used to determine the element contents of Li, Fe and P in the positive electrode powder.

[0023] Preferably, in step 6), the waste diaphragm is broken into small pieces smaller than 0.5 cm.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention uses lithium in the negative electrode of waste lithium batteries as a lithium source, and waste diaphragms as a reducing agent and a carbon source, and solid-state sintering the lithium source, the waste diaphragms and the waste lithium iron phosphate positive electrode material. During the sintering process, Li2CO3 can be used as a lithium source to supplement the missing lithium, and the waste diaphragms can release reducing gases to eliminate Fe Li Anti-site defects, and the diaphragm will become an amorphous carbon layer during the pyrolysis process to cover the surface of the positive electrode material, which can further improve the electrochemical performance of the positive electrode material.

[0026] The lithium salt, waste diaphragm and positive electrode material are mixed and calcined at high temperature. The positive electrode material of waste lithium iron phosphate battery is directly repaired. The invention simplifies the regeneration process, reduces the cost of the entire regeneration process, has high economic benefits, can repair batteries of different capacities, has a certain universality and realizes the reuse of different components of waste batteries.

[0027] This invention not only realizes the repair and regeneration of waste lithium iron phosphate positive electrodes, but also reuses the lithium in the negative electrode and waste diaphragms to reduce the regeneration cost compared to the current technology, solves the waste of lithium resources and the treatment problems of waste diaphragms, and achieves the goal of "waste + waste = new". BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a flow chart of the method of the present invention;

[0029] Figure 2 This is the cycle performance diagram of the positive electrode material of the regenerated lithium iron phosphate battery at 0.3C. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0031] The present invention provides a method for regenerating lithium iron phosphate positive electrode materials with the assistance of negative electrode lithium and waste diaphragm, for details, see Figure 1 , including the following steps:

[0032] Step 1: Preprocessing:

[0033] 1. Discharge and disassemble the waste lithium iron phosphate battery to obtain and collect the positive electrode material, the separator, and the negative electrode material. The waste lithium iron phosphate battery is discharged using a NaCl solution.

[0034] 2. Calcine the waste lithium iron phosphate positive electrode sheet at high temperature in a tube furnace to remove the binder, and obtain the waste lithium iron phosphate positive electrode powder after grinding;

[0035] 3. Place the negative electrode sheet in deionized water and separate the negative electrode material and copper foil by ultrasound.

[0036] Preferably, when removing the binder, the high temperature pyrolysis conditions are: a temperature range of 450° C. to 550° C., and a time of 1 h to 3 h.

[0037] Preferably, when separating the negative electrode material and the copper foil, the ultrasonic power is 100 W and the ultrasonic time is 0.5 to 1 h.

[0038] 3. Use ICP-OES to detect the content of lithium, iron, phosphorus and other elements in the waste lithium iron phosphate positive electrode powder;

[0039] 4. Cut the used diaphragm into small pieces.

[0040] Preferably, the size of the diaphragm should be as small as possible and less than 0.5 cm×0.5 cm.

[0041] Step 2: Extraction of negative electrode lithium

[0042] 1. Place the negative electrode material in deionized water and stir for 2 to 3 hours to obtain a lithium-rich solution and graphite material.

[0043] 2. Filter and collect the filtrate and graphite.

[0044] 3. Add Na2CO3 to the filtrate and stir at 90°C to allow the solution to gradually evaporate to obtain Li2CO3 solid.

[0045] Step 3: Repair and regeneration:

[0046] 1. Evenly mix the waste lithium iron phosphate cathode powder with the recycled Li2CO3 and the diaphragm in different proportions;

[0047] 2. Place the mixed material in a tube furnace, and heat it to different temperatures under the introduction of protective gas and keep it for a certain period of time for regeneration. After cooling down, the repaired and regenerated lithium iron phosphate positive electrode material is obtained.

[0048] Preferably, the protective gas comprises nitrogen or argon.

[0049] Preferably, the temperature range is 600-800° C., and the insulation time is 4 h to 8 h.

[0050] The present invention is described in detail below with reference to specific embodiments.

[0051] Example 1

[0052] The present embodiment provides a method for regenerating a lithium iron phosphate positive electrode material with the assistance of negative electrode lithium and waste diaphragm, comprising the following steps:

[0053] Preprocessing:

[0054] Step 1: The waste lithium iron phosphate battery is immersed in a 5wt% NaCl solution for 24 hours to release the residual power, and then placed in a 50°C forced air drying oven for 24 hours.

[0055] Step 2: Manually disassemble the battery and collect the positive electrode, separator, and negative electrode respectively. Quickly soak the positive electrode and negative electrode in DMC solution to remove the surface electrolyte.

[0056] Step 3: Place the positive electrode sheet in a tube furnace, and under argon protection, heat it to 500°C at a heating rate of 5°C / min and keep it for 2 hours to remove the binder PVDF.

[0057] Step 4: Manually separate the positive electrode active material and the aluminum foil, and grind the positive electrode active material into powder. The Li / Fe molar ratio in the positive electrode active material was measured by ICP-OES to be 0.9 / 1.

[0058] Negative electrode lithium extraction:

[0059] Step 5: Place the negative electrode sheet in deionized water and ultrasonicate it in 100W ultrasound for 1 hour to obtain negative electrode graphite and complete copper foil.

[0060] Step 6: Take out the copper foil, keep the negative electrode in the deionized water, and stir at room temperature for 2 hours.

[0061] Step seven: Filter to obtain a lithium-containing solution and negative electrode graphite.

[0062] Step 8: Through ICP-OES detection, the lithium content in the lithium-containing solution is obtained to be 0.56 mg / L.

[0063] Step 9: Add Na2CO3 to the lithium-containing solution, raise the temperature to 90°C, and continue heating and stirring until the solution evaporates and a white solid appears, which is Li2CO3.

[0064] Step 10: Calculate the amount of lithium salt to be added based on the Li / Fe ratio measured in step 4, so that the Li / Fe ratio is maintained at a normal level (1 to 1.05):1 after regeneration.

[0065] Step 11: Cut the waste diaphragm into small pieces less than 0.5 cm; mix 1g of positive electrode active material, 40mg of Li2CO3 and 50mg of diaphragm evenly and place in a tube furnace. Heat to 500℃ at a heating rate of 5℃ / min under argon protection, keep warm for one hour, then heat to 700℃ at a heating rate of 5℃ / min and keep warm for 6h. After cooling naturally, regenerated positive electrode material is obtained.

[0066] Step 12: Wash the regenerated positive electrode material with deionized water three times, filter, and dry at 80°C.

[0067] CR2032 button cells were used to characterize the electrochemical properties of the synthesized materials.

[0068] First, the positive electrode active material, conductive agent acetylene black, and binder (PVDF mass fraction 10%) were mixed in a mass ratio of 8:1:1, and then an appropriate amount of N-methylpyrrolidone was added as a solvent and stirred thoroughly. The resulting slurry was coated on a copper foil and dried at 120°C under vacuum for 10 hours, and then a disc with a diameter of 12 mm was cut out with a cutting machine, and compacted under 20 MPa to obtain a button battery positive electrode sheet.

[0069] Figure 2This is a cycle performance diagram of a button-type full battery after multiple cycles at 0.3C. It can be seen from the figure that the regenerated positive electrode material of this embodiment has good cycle performance, proving that the performance of the regenerated positive electrode material meets the relevant industry standards.

[0070] Example 2

[0071] The present embodiment provides a method for waste diaphragm-assisted regeneration of lithium iron phosphate positive electrode material, comprising the following steps:

[0072] Preprocessing:

[0073] Step 1: The waste lithium iron phosphate battery is immersed in a 5wt% NaCl solution for 24 hours to release the residual power, and then placed in a 50°C forced air drying oven for 24 hours.

[0074] Step 2: Manually disassemble the battery and collect the positive electrode, separator, and negative electrode respectively. Quickly soak the positive electrode and negative electrode in DMC solution to remove the surface electrolyte.

[0075] Step 3: Place the positive electrode sheet in a tubular furnace, and under argon protection, heat it to 450°C at a heating rate of 5°C / min and keep it for 3 hours to remove the binder PVDF.

[0076] Step 4: Manually separate the positive electrode active material and aluminum foil, and grind the positive electrode active material into powder. The Li / Fe molar ratio in the positive electrode active material was measured by ICP-OES to be 0.9 / 1.

[0077] Negative electrode lithium extraction:

[0078] Step 5: Place the negative electrode sheet in deionized water and ultrasonicate it in 100W ultrasound for 0.5h to obtain negative electrode graphite and complete copper foil.

[0079] Step 6: Take out the copper foil, keep the negative electrode in the deionized water, and stir at room temperature for 3 hours.

[0080] Step seven: Filter to obtain a lithium-containing solution and negative electrode graphite.

[0081] Step 8: Through ICP-OES detection, the lithium content in the lithium-containing solution is obtained to be 0.56 mg / L.

[0082] Step 9: Add Na2CO3 to the lithium-containing solution, raise the temperature to 90°C, and continue heating and stirring until the solution evaporates and a white solid appears, which is Li2CO3.

[0083] Step 10: Calculate the amount of lithium salt to be added based on the Li / Fe ratio measured in step 4, so that the Li / Fe ratio is maintained at a normal level (1 to 1.05):1 after regeneration.

[0084] Step 11: Cut the waste diaphragm into small pieces less than 0.5 cm; mix 1g of positive electrode active material, 40mg of Li2CO3 and 100mg of diaphragm evenly and place in a tube furnace. Heat to 500℃ at a heating rate of 5℃ / min under argon protection, keep warm for one hour, then heat to 600℃ at a heating rate of 5℃ / min and keep warm for 8h. After cooling naturally, regenerated positive electrode material is obtained.

[0085] Step 12: Wash the regenerated positive electrode material with deionized water three times, filter, and dry at 80°C.

[0086] Example 3

[0087] The present embodiment provides a method for waste diaphragm-assisted regeneration of lithium iron phosphate positive electrode material, comprising the following steps:

[0088] Preprocessing:

[0089] Step 1: The waste lithium iron phosphate battery is immersed in a 5wt% NaCl solution for 24 hours to release the residual power, and then placed in a 50°C forced air drying oven for 24 hours.

[0090] Step 2: Manually disassemble the battery and collect the positive electrode, separator, and negative electrode respectively. Quickly soak the positive electrode and negative electrode in DMC solution to remove the surface electrolyte.

[0091] Step 3: Place the positive electrode sheet in a tube furnace, and under argon protection, heat it to 550°C at a heating rate of 5°C / min and keep it for 1 hour to remove the binder PVDF.

[0092] Step 4: Manually separate the positive electrode active material and aluminum foil, and grind the positive electrode active material into powder. The Li / Fe molar ratio in the positive electrode active material was measured by ICP-OES to be 0.9 / 1.

[0093] Negative electrode lithium extraction:

[0094] Step 5: Place the negative electrode sheet in deionized water and ultrasonicate it in 100W ultrasound for 0.6h to obtain negative electrode graphite and complete copper foil.

[0095] Step 6: Take out the copper foil, keep the negative electrode in the deionized water, and stir at room temperature for 2.5 hours.

[0096] Step seven: Filter to obtain a lithium-containing solution and negative electrode graphite.

[0097] Step 8: Through ICP-OES detection, the lithium content in the lithium-containing solution is obtained to be 0.56 mg / L.

[0098] Step 9: Add Na2CO3 to the lithium-containing solution, raise the temperature to 90°C, and continue heating and stirring until the solution evaporates and a white solid appears, which is Li2CO3.

[0099] Step 10: Calculate the amount of lithium salt to be added based on the Li / Fe ratio measured in step 4, so that the Li / Fe ratio is maintained at a normal level (1 to 1.05):1 after regeneration.

[0100] Step 11: Cut the waste diaphragm into small pieces less than 0.5 cm; mix 1g of positive electrode active material, 40mg of Li2CO3 and 100mg of diaphragm evenly and place in a tube furnace. Heat to 500℃ at a heating rate of 5℃ / min under argon protection, keep warm for one hour, then heat to 800℃ at a heating rate of 5℃ / min and keep warm for 4h. After cooling naturally, regenerated positive electrode material is obtained.

[0101] Step 12: Wash the regenerated positive electrode material with deionized water three times, filter, and dry at 100°C.

[0102] Example 4

[0103] The present embodiment provides a method for waste diaphragm-assisted regeneration of lithium iron phosphate positive electrode material, comprising the following steps:

[0104] Preprocessing:

[0105] Step 1: The waste lithium iron phosphate battery is immersed in a 5wt% NaCl solution for 24 hours to release the residual power, and then placed in a 50°C forced air drying oven for 24 hours.

[0106] Step 2: Manually disassemble the battery and collect the positive electrode, separator, and negative electrode respectively. Quickly soak the positive electrode and negative electrode in DMC solution to remove the surface electrolyte.

[0107] Step 3: Place the positive electrode sheet in a tube furnace, and under argon protection, heat it to 500°C at a heating rate of 5°C / min and keep it for 2 hours to remove the binder PVDF.

[0108] Step 4: Manually separate the positive electrode active material and aluminum foil, and grind the positive electrode active material into powder. The Li / Fe molar ratio in the positive electrode active material was measured by ICP-OES to be 0.9 / 1.

[0109] Negative electrode lithium extraction:

[0110] Step 5: Place the negative electrode sheet in deionized water and ultrasonicate it in 100W ultrasound for 1 hour to obtain negative electrode graphite and complete copper foil.

[0111] Step 6: Take out the copper foil, keep the negative electrode in the deionized water, and stir at room temperature for 2.5 hours.

[0112] Step seven: Filter to obtain a lithium-containing solution and negative electrode graphite.

[0113] Step 8: Through ICP-OES detection, the lithium content in the lithium-containing solution is obtained to be 0.56 mg / L.

[0114] Step 9: Add Na2CO3 to the lithium-containing solution, raise the temperature to 90°C, and continue heating and stirring until the solution evaporates and a white solid appears, which is Li2CO3.

[0115] Step 10: Calculate the amount of lithium salt to be added based on the Li / Fe ratio measured in step 4, so that the Li / Fe ratio is maintained at a normal level (1 to 1.05):1 after regeneration.

[0116] Step 11: Cut the waste diaphragm into small pieces less than 0.5 cm; mix 1g of positive electrode active material, 40mg of Li2CO3 and 150mg of diaphragm evenly and place in a tube furnace. Heat to 500℃ at a heating rate of 5℃ / min under argon protection, keep warm for one hour, then heat to 750℃ at a heating rate of 5℃ / min and keep warm for 4h. After cooling naturally, regenerated positive electrode material is obtained.

[0117] Step 12: Wash the regenerated positive electrode material with deionized water three times, filter, and dry at 100°C.

Claims

1. A method for regenerating lithium iron phosphate positive electrode materials with the assistance of negative electrode lithium and waste diaphragm, characterized in that The steps include: 1) Pre-treating waste lithium iron phosphate batteries to obtain waste lithium iron phosphate positive electrode sheets, waste diaphragms and negative electrode sheets; 2) placing the negative electrode sheet in deionized water and separating the negative electrode material and the copper foil by ultrasound; 3) placing the negative electrode material in deionized water and stirring to obtain a lithium-rich solution and a negative electrode graphite material; 4) adding sodium carbonate to the lithium-containing solution obtained in step 3) and stirring at high temperature until the solution evaporates and an off-white solid appears; filtering out the white solid, rinsing it and drying it to obtain Li2CO3; 5) calcining the waste lithium iron phosphate positive electrode sheet at high temperature in a tube furnace to remove the binder, and then grinding to obtain the waste lithium iron phosphate positive electrode powder, and determining the content of lithium, iron and phosphorus in the waste lithium iron phosphate positive electrode powder; 6) cutting the waste diaphragm obtained in step 1) into small pieces; 7) uniformly mixing the waste positive electrode powder obtained in step 5) and the waste diaphragm pieces obtained in step 6); 8) The mixed material obtained in step 7) and the Li2CO3 solid obtained in step 4) are mixed evenly, and the amount of Li2CO3 solid added is determined according to the lithium-iron element ratio determined in step 5). After mixing, the mixture is placed in a tubular furnace, a protective gas is introduced, and the temperature is raised to 500°C at 5°C / min and maintained for 1 hour, and then the temperature is raised to 600-800°C at 5°C / min and maintained for 4-8 hours. After cooling, the regenerated lithium iron phosphate positive electrode material is obtained.

2. The method for regenerating lithium iron phosphate positive electrode material by using negative electrode lithium and waste diaphragm as auxiliary according to claim 1, characterized in that: In the step 1), the waste lithium iron phosphate battery is immersed in a 5wt% NaCl solution and allowed to stand for 24 hours to release the residual power; then placed in a blast drying oven for 24 hours and manually disassembled to collect the positive electrode sheet, the separator, and the negative electrode sheet, and placed in a DMC solution to remove the surface electrolyte.

3. The method for regenerating lithium iron phosphate positive electrode material by using negative electrode lithium and waste diaphragm as auxiliary according to claim 1, characterized in that: In the step 2), the ultrasonic power is 100 W and the ultrasonic time is 0.5 to 1 h.

4. The method for regenerating lithium iron phosphate positive electrode material by using negative electrode lithium and waste diaphragm as auxiliary according to claim 1, characterized in that: In the step 3), the negative electrode material is stirred in deionized water for 2 to 3 hours.

5. The method for regenerating lithium iron phosphate positive electrode material by using negative electrode lithium and waste diaphragm as auxiliary according to claim 1, characterized in that: The lithium-containing solution in step 4) is stirred at 90° C. until the solution evaporates and an off-white solid appears.

6. The method for regenerating lithium iron phosphate positive electrode material by using negative electrode lithium and waste diaphragm as auxiliary according to claim 1, characterized in that: In the step 5), the high temperature calcination temperature is 450-550° C., and the calcination time is 1-3 hours.

7. The method for regenerating lithium iron phosphate positive electrode material by using negative electrode lithium and waste diaphragm as auxiliary according to claim 1, characterized in that: In the step 5), an inductively coupled plasma emission spectrometer is used to determine the element contents of Li, Fe and P in the positive electrode powder.

8. The method for regenerating lithium iron phosphate positive electrode material with the aid of negative electrode lithium and waste diaphragm according to claim 1, characterized in that: In the step 6), the waste diaphragm is broken into small pieces smaller than 0.5 cm.

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