Method for recycling waste lithium iron phosphate battery cell material

Abstract

The application relates to the technical field of lithium iron phosphate battery recycling, in particular to a method for recycling waste lithium iron phosphate battery materials. Specifically, after the waste lithium iron phosphate battery is discharged, the battery is disassembled and separated under an inert atmosphere, and the battery is separately collected; the battery is mechanically pulverized after high-temperature calcination, and lithium iron phosphate coarse powder, copper powder and aluminum powder are obtained through vibration screening; the lithium iron phosphate coarse powder is added into an acid solution for leaching, the acid leaching solution is adsorbed and impurity-removed through metal impurity adsorption resin, and then lithium carbonate, ammonium dihydrogen phosphate and ferrous oxalate are added; after uniform stirring, drying, ball milling and roasting, lithium iron phosphate powder is obtained. The metal impurity adsorption resin has good complexing and stabilizing effects on various metal ions, so that the high purity of the lithium iron phosphate is ensured, and comprehensive resource utilization of the waste lithium iron phosphate battery is realized.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of lithium iron phosphate battery recycling, and in particular to a method for recycling waste lithium iron phosphate battery materials. BACKGROUND

[0002] China has become the world's largest new energy vehicle market, and the development of lithium battery recycling and cascade utilization will not only avoid resource waste and environmental pollution, but also bring considerable economic benefits and investment opportunities. At present, the recycling of waste power lithium ion batteries mainly involves disassembly and recycling: when the capacity of a battery decreases to below 50%, the battery cannot be used any more, and the battery can only be disassembled and recycled. Waste lithium batteries contain valuable metals such as copper, aluminum, iron and lithium, and are an indispensable secondary resource. Therefore, the recycling and utilization of waste lithium batteries have become one of the recent research focuses.

[0003] A method for separating and recycling waste lithium iron phosphate positive and negative active materials (patent application number: CN202210281138.8) includes the following steps: placing waste lithium iron phosphate battery positive and negative active materials on a conveying belt and under alternating current, and adding an electrostatic field in the alternating current environment, so that the waste lithium iron phosphate battery positive and negative active materials are separated.

[0004] A method for recycling and preparing lithium iron phosphate from waste lithium iron phosphate batteries (patent application number: CN201210203380.X) includes the following steps: 1) after the recovered waste lithium iron phosphate battery is disassembled, the battery shell is peeled off, then soaked, and the pole piece and the positive and negative electrode powder are separated by the method of alternately ultrasonic and mechanical stirring, the pole piece and the separator are taken out, and a mixed solution is obtained; 2) the mixed solution is preliminarily ball milled, and the preliminarily ball milled slurry is dried; 3) the dried material is calcined in an oxidizing atmosphere to obtain a recycled material, iron source and phosphorus source are added, and new lithium iron phosphate raw materials are selectively added, then a carbon source is added and high-energy ball milled, and after drying, a recycled waste material pre-burning material is obtained; 4) the recycled waste material pre-burning material is treated by microwave sintering or solid phase sintering in a protective atmosphere to obtain a lithium iron phosphate product.

[0005] A kind of recovery method of waste lithium iron phosphate battery powder, patent application number: CN202210688537.6;Belong to lithium ion battery recycling technical field, specifically related to a kind of recovery method of waste lithium iron phosphate battery powder.To the filtrate obtained in step S5, add stabilizer, stir, heat to react, adjust the pH value of system to 2~3, precipitate, separate, obtain iron sulfate.The stabilizer includes first complexing agent and second complexing agent, the first complexing agent is one or several of tartaric acid, heptose salt, sodium gluconate, sodium alginate, sodium citrate;The second complexing agent is one or several of monoethanolamine, diethanolamine, triethanolamine.The two kinds of complexing agents have synergistic effect, can make system in relatively stable state, so that the content of impurity metal ions is less and precipitates, and the complexing stability effect is good, effective for a variety of metal ions, to ensure the high purity of iron phosphate precipitate.Further, the two kinds of complexing agents are also easy to biodegrade, and play a good auxiliary role for subsequent wastewater treatment.

[0006] However, the applicant believes that the above-mentioned disclosed technology adopts disassembly and separation of the positive and negative electrodes of the battery, which has low production efficiency and incomplete separation of effective components in the battery, and also has certain safety hazards.How to economically and effectively treat waste lithium batteries has attracted more and more attention.The stabilizer of the prior art uses two kinds of complexing agents, which increases the organic matter residue in wastewater, easily causes secondary pollution and increases the cost of wastewater treatment. SUMMARY

[0007] In view of the above problems, the present application provides a method for recycling waste lithium iron phosphate battery materials, which realizes comprehensive resource utilization of waste lithium iron phosphate batteries.

[0008] Another object of the present application is to provide lithium iron phosphate powder obtained by the above preparation method.

[0009] The object of the present application is achieved by the following technical solutions:

[0010] A method for recycling waste lithium iron phosphate battery materials, characterized in that it comprises the following steps:

[0011] A1: after discharging the waste lithium iron phosphate battery to a voltage not higher than 2.0V, disassembling and separating in an inert atmosphere, collecting the battery core separately;

[0012] A2: put the battery core into a muffle furnace and calcine for 3-5h in an inert atmosphere, mechanically crush after cooling to room temperature after calcination, and separate by vibration screen to obtain lithium iron phosphate coarse powder, copper powder and aluminum powder;

[0013] A3: add lithium iron phosphate coarse powder to sulfuric acid solution and heat leaching, obtain acid leaching solution and filter residue after filtration, and obtain high-carbon graphite after drying the filter residue;

[0014] A4: 100-140 parts of the acid leaching solution is added with 4-8 parts of metal impurity adsorption resin, stirring at 40-50℃ for 50-100 minutes, and filtering;

[0015] A5: lithium carbonate, ammonium dihydrogen phosphate, and ferrous oxalate are further added into the filtrate, stirring uniformly, drying, and ball milling to obtain a fine powder mixture, and the mixture is placed in a tube furnace for calcination for 20-30h, and the calcined mixture is ground for 1-2h to obtain lithium iron phosphate powder.

[0016] As a further supplement to the above technical solution, the inert atmosphere in steps A1 and A2 is selected from at least one of nitrogen, helium, or argon.

[0017] As a further supplement to the above technical solution, the calcination temperature in step A2 is 500-750℃.

[0018] As a further supplement to the above technical solution, the concentration of the sulfuric acid solution in step A3 is 18-32%, and the amount of the sulfuric acid solution is 1.5-4.5 times the amount of the lithium iron coarse powder.

[0019] As a further supplement to the above technical solution, the metal impurity adsorption resin in step A4 is prepared by the following steps:

[0020] S1: 100-200 parts of polystyrene macroporous sulfonic acid resin is placed in an electron beam under irradiation, the electron beam energy is 1.6MeV, the dose rate is 100-500Gy / s, the irradiation time is 5-15min, and after the end of irradiation, the temperature is lowered, purged, and then the irradiated polystyrene macroporous sulfonic acid resin is taken out;

[0021] S2: 0.05-0.5 parts of tetra(4-boronic acid phenyl)ethylene, 0.8-2 parts of 5,5-divinyl-2,2-bipyridine, 1-3 parts of initiator, 200-300 parts of toluene, and 20-40 parts of irradiated polystyrene macroporous sulfonic acid resin are added to a closed stirring reaction kettle, nitrogen is introduced, stirring is carried out at 80-100℃ for 10-15h, and after the reaction is completed, filtering and drying are carried out to obtain a metal impurity adsorption resin.

[0022] As a further supplement to the above technical solution, the initiator is selected from at least one of azobisisobutyronitrile, azobisisoheptyl nitrile, and benzoyl peroxide.

[0023] As a further supplement to the above technical solution, the polystyrene macroporous sulfonic acid resin is a commercially available product, such as D001 resin, D006 resin, D008 resin, and C150 resin.

[0024] As a further supplement to the above technical solution, the filtrate, lithium carbonate, ammonium dihydrogen phosphate, and ferrous oxalate in step A5 are controlled at a molar ratio of n(Fe):n(Li):n(P) = 1:1.01-1.08:1.01-1.08.

[0025] As a further supplement to the above technical solution, the tube furnace roasting process in step A5 is divided into two steps: the roasting temperature is controlled at 450-550 DEG C for 10-15 h, and then the temperature is raised to 700-800 DEG C for 10-15 h.

[0026] Grafting reaction mechanism:

[0027] Through initiator induction, tetra(4-boronic acid phenyl) ethylene, 10-20 parts of 5,5-divinyl-2,2-bipyridine, and irradiated polystyrene macroporous sulfonic acid resin undergo a free radical polymerization reaction to polymerize the monomers onto the membrane surface to generate a metal impurity adsorption resin; all impurities that may exist in the waste lithium iron phosphate battery powder can be adsorbed and removed, and the impurities can be separated from the acid leaching solution through simple filtration, and the adsorption resin will not enter the product and waste liquid, thereby improving the purity of the lithium iron phosphate powder.

[0028] The beneficial effects achieved by the above technical solution of the present application are as follows:

[0029] (1) The metal impurity adsorption resin has good complexing stability and is effective for various metal ions, thereby ensuring high purity of the lithium iron phosphate.

[0030] (2) The adsorption resin will not enter the product and waste liquid, thereby overcoming the shortcomings of the prior art of adding a stabilizer to increase organic impurities in subsequent wastewater. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the present application will be described clearly and completely below in combination with examples. If the specific conditions are not specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are used. If the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be purchased on the market.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the present application is only for the purpose of describing specific embodiments and is not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0033] The purity of the lithium iron phosphate prepared by the specific embodiments of the present method is tested by the following method:

[0034] 1. YS / T 1028.1-2015 Determination of iron content in lithium iron phosphate - potassium dichromate titration method;

[0035] 2. YS / T 1028.2-2015 Determination of lithium content in lithium iron phosphate - flame photometry method;

[0036] 3. YS / T 1028.3-2015 Determination of phosphorus content in lithium iron phosphate - gravimetric method.

[0037] Example 1

[0038] A method for recycling waste lithium iron phosphate battery materials, characterized in that it comprises the following steps:

[0039] A1: After discharging the waste lithium iron phosphate battery to a voltage not higher than 2.0V, disassembling and separating it in an inert atmosphere, and collecting the battery cell separately;

[0040] A2: Put the battery cell into a muffle furnace and calcine it in an inert atmosphere for 3h, then mechanically crush it after cooling to room temperature, and separate the lithium iron phosphate coarse powder, copper powder and aluminum powder through a vibrating screen;

[0041] A3: Add the lithium iron phosphate coarse powder to a sulfuric acid solution and heat it to leach, then filter to obtain an acid leaching solution and a filter residue, and obtain high-carbon graphite by drying the filter residue;

[0042] A4: Add 4g of metal impurity adsorption resin to 100g of the acid leaching solution, stir at 40℃ for 100 minutes, and filter;

[0043] A5: Add lithium carbonate, ammonium dihydrogen phosphate and ferrous oxalate to the filtrate, stir evenly, dry, ball mill to obtain a fine powder mixture, place the mixture in a tube furnace and calcine it for 20h, and grind the calcined mixture for 1h to obtain lithium iron phosphate powder.

[0044] The inert atmosphere in steps A1 and A2 is selected from nitrogen.

[0045] The calcination temperature in step A2 is 500℃.

[0046] The concentration of the sulfuric acid solution in step A3 is 18%, and the amount of the sulfuric acid solution is 4.5 times the amount of the lithium iron phosphate coarse powder.

[0047] The preparation of the metal impurity adsorption resin in step A4 comprises the following steps:

[0048] S1: Place 100g of polystyrene macroporous sulfonic acid resin in an irradiation box under an electron beam, with an electron beam energy of 1.6MeV, a dose rate of 100Gy / s, and an irradiation time of 5min, stop irradiation after completion, cool down, purge, and then take out the irradiated polystyrene macroporous sulfonic acid resin;

[0049] S2: 0.1 g of tetra(4-boronic acid phenyl) ethylene, 0.8 g of 5,5-divinyl-2,2-bipyridine, 1 g of initiator, 200 g of toluene, and 20 g of irradiated polystyrene macroporous sulfonic acid resin were added to a closed stirred reaction kettle, nitrogen was introduced, stirring was carried out at 80°C for 10 h, and after the reaction was completed, filtration and drying were carried out to obtain a metal impurity adsorption resin.

[0050] The initiator is selected from azobisisobutyronitrile.

[0051] The polystyrene macroporous sulfonic acid resin is a commercially available product, and is a D001 resin.

[0052] In step A5, the filtrate, lithium carbonate, ammonium dihydrogen phosphate, and ferrous oxalate are controlled at a molar ratio of n(Fe):n(Li):n(P) = 1:1.03:1.03.

[0053] In step A5, the tube furnace calcination process is divided into two steps: the calcination temperature is controlled at 450°C for 15 h, and then the temperature is increased to 700°C for 15 h.

[0054] According to the analysis and calculation, the purity of the lithium iron phosphate material prepared in this example is 98.7%.

[0055] Example 2

[0056] A method for recycling waste lithium iron phosphate battery materials, characterized in that it comprises the following steps:

[0057] A1: After discharging the waste lithium iron phosphate battery to a voltage not higher than 2.0V, it is disassembled and separated under an inert atmosphere, and the battery cell is collected separately;

[0058] A2: The battery cell is placed in a muffle furnace and calcined under an inert atmosphere for 4 h, and after calcination, it is air-cooled to room temperature and mechanically crushed, and then lithium iron phosphate coarse powder, copper powder and aluminum powder are obtained by vibration screening;

[0059] A3: The lithium iron phosphate coarse powder is added to a sulfuric acid solution and heated for leaching, and after filtration, an acid leaching solution and a filter residue are obtained, and the filter residue is dried to obtain high-carbon graphite;

[0060] A4: 5 g of metal impurity adsorption resin is added to 115 g of the acid leaching solution, stirred at 40°C for 80 minutes, and filtered;

[0061] A5: Lithium carbonate, ammonium dihydrogen phosphate, and ferrous oxalate are added to the filtrate, stirred uniformly and dried, ball milled to obtain a fine powder mixture, and the mixture is placed in a tube furnace and calcined for 25 h, and after calcination, the mixture is ground for 1 h to obtain lithium iron phosphate powder.

[0062] The inert atmosphere in steps A1 and A2 is selected from nitrogen.

[0063] The calcination temperature in step A2 is 600℃.

[0064] The concentration of the sulfuric acid solution in step A3 is 24%, and the amount of the sulfuric acid solution is 4 times the amount of the lithium iron crude powder.

[0065] The metal impurity adsorption resin in step A4 is prepared by the following steps:

[0066] S1: Place a 130g polystyrene macroporous sulfonic acid resin irradiation box under an electron beam, with an electron beam energy of 1.6MeV, a dose rate of 250Gy / s, and a radiation time of 8min. After stopping the irradiation, cool down, purge, and then take out the irradiated polystyrene macroporous sulfonic acid resin;

[0067] S2: In a stirred tank, add 0.25g of tetra(4-boronic acid phenyl)ethylene, 1.2g of 5,5-divinyl-2,2-bipyridine, 1.5g of initiator, 230g of toluene, and 28g of the irradiated polystyrene macroporous sulfonic acid resin into a sealed stirred reaction kettle, and introduce nitrogen. Stir at 85℃ for 15h, and then filter and dry to obtain the metal impurity adsorption resin.

[0068] The initiator is selected from azobisisobutyronitrile.

[0069] The polystyrene macroporous sulfonic acid resin is a commercially available product, and is D006 resin.

[0070] In step A5, the molar ratio of the filtrate, lithium carbonate, ammonium dihydrogen phosphate, and ferrous oxalate is controlled to be n(Fe):n(Li):n(P)=1:1.1.05:1.05.

[0071] In step A5, the tube furnace roasting process is divided into two steps: control the roasting temperature to be 480℃ for 13h, and then increase the temperature to 750℃ for 15h.

[0072] According to the analysis and calculation, the purity of the lithium iron phosphate material prepared in this example is 99.1%.

[0073] Example 3

[0074] A method for recycling waste lithium iron phosphate battery materials, characterized in that it comprises the following steps:

[0075] A1: After discharging the waste lithium iron phosphate battery to a voltage not higher than 2.0V, disassemble and separate it in an inert atmosphere, and collect the battery core separately;

[0076] A2: Place the battery core in a muffle furnace and calcine it in an inert atmosphere for 4h. After calcination, cool it to room temperature and mechanically crush it. Then, separate the lithium iron phosphate crude powder, copper powder, and aluminum powder through a vibrating screen;

[0077] A3: adding the lithium iron phosphate coarse powder into the sulfuric acid solution to heat leaching, obtaining the acid leaching solution and the filter residue after filtration, and obtaining the high-carbon graphite after drying the filter residue;

[0078] A4: adding 6g of metal impurity adsorption resin into 130g of the acid leaching solution, stirring at 45℃ for 60 minutes, and filtering;

[0079] A5: adding lithium carbonate, ammonium dihydrogen phosphate, and ferrous oxalate into the filtrate, stirring uniformly, drying, ball milling to obtain a fine powder mixture, placing the mixture in a tube furnace to sinter for 28h, and obtaining the lithium iron phosphate powder after milling the sintered mixture for 2h.

[0080] The inert atmosphere in the steps A1 and A2 is selected from helium.

[0081] The calcination temperature in the step A2 is 700℃.

[0082] The concentration of the sulfuric acid solution in the step A3 is 28%, and the amount of the sulfuric acid solution is 2.5 times of the lithium iron phosphate coarse powder.

[0083] The metal impurity adsorption resin in the step A4 is prepared by the following steps:

[0084] S1: placing 175g of polystyrene macroporous sulfonic acid resin in an irradiation box under an electron beam, with an electron beam energy of 1.6MeV, a dose rate of 400Gy / s, and a radiation time of 12min, stopping the irradiation after completion, cooling, purging, and then taking out the irradiated polystyrene macroporous sulfonic acid resin;

[0085] S2: adding 0.35g of tetra(4-boronic acid phenyl)ethylene, 1.6g of 5,5-divinyl-2,2-bipyridine, 3g of initiator, 280g of toluene, and 34g of the irradiated polystyrene macroporous sulfonic acid resin into a closed stirring reaction kettle, purging with nitrogen, stirring at 95℃ for 10h, filtering after completion of the reaction, drying, and obtaining the metal impurity adsorption resin.

[0086] The initiator is selected from azobis diisopropyl cyanide.

[0087] The polystyrene macroporous sulfonic acid resin is a commercially available product, which is D008 resin.

[0088] The molar ratio of the filtrate, lithium carbonate, ammonium dihydrogen phosphate, and ferrous oxalate in the step A5 is controlled to be n(Fe):n(Li):n(P)=1:1.08:1.08.

[0089] The tube furnace sintering process in the step A5 is divided into two steps: controlling the sintering temperature to be 500℃ for 12h, and then increasing the temperature to 775℃ for 15h.

[0090] The purity of the lithium iron phosphate material prepared in this example is 99.4% after analysis and calculation.

[0091] Example 4

[0092] A method for recycling waste lithium iron phosphate battery materials, characterized in that it comprises the following steps:

[0093] A1: After discharging the waste lithium iron phosphate battery to a voltage not higher than 2.0V, disassembling and separating it in an inert atmosphere, and collecting the battery core separately;

[0094] A2: Put the battery core into a muffle furnace and calcine it in an inert atmosphere for 5h, then mechanically crush it after air cooling to room temperature, and separate the lithium iron phosphate coarse powder, copper powder and aluminum powder through a vibrating screen;

[0095] A3: Add the lithium iron phosphate coarse powder into a sulfuric acid solution for heating leaching, and obtain an acid leaching solution and a filter residue after filtration, and obtain high-carbon graphite after drying the filter residue;

[0096] A4: Add 8g of metal impurity adsorption resin into 140g of the acid leaching solution, stir at 50℃ for 100 minutes, and filter;

[0097] A5: Add lithium carbonate, ammonium dihydrogen phosphate and ferrous oxalate into the filtrate, stir uniformly, dry, ball mill to obtain a fine powder mixture, place the mixture in a tube furnace for calcination for 30h, and obtain lithium iron phosphate powder after grinding the calcined mixture for 2h.

[0098] The inert atmosphere in steps A1 and A2 is selected from argon.

[0099] The calcination temperature in step A2 is 750℃.

[0100] The concentration of the sulfuric acid solution in step A3 is 32%, and the amount of the sulfuric acid solution is 1.5 times the amount of the lithium iron phosphate coarse powder.

[0101] The preparation of the metal impurity adsorption resin in step A4 comprises the following steps:

[0102] S1: Place a 200g polystyrene macroporous sulfonic acid resin irradiation box under an electron beam, with an electron beam energy of 1.6MeV, a dose rate of 500Gy / s, and a radiation time of 15min, stop irradiation after completion, cool down, purge, and then take out the irradiated polystyrene macroporous sulfonic acid resin;

[0103] S2: Add 0.5g of tetra(4-boronic acid phenyl)ethylene, 2g of 5,5-divinyl-2,2-bipyridine, 3g of initiator, 300g of toluene, and 40g of the irradiated polystyrene macroporous sulfonic acid resin into a sealed stirring reaction kettle, introduce nitrogen, stir at 100℃ for 10h, filter after reaction, and dry to obtain the metal impurity adsorption resin.

[0104] The initiator is selected from benzoyl peroxide.

[0105] The polystyrene macroporous sulfonic acid resin is a commercially available product, which is C150 resin.

[0106] The filtrate, lithium carbonate, ammonium dihydrogen phosphate, and ferrous oxalate in step A5 are controlled in a molar ratio of n(Fe):n(Li):n(P) = 1:1.08:1.08.

[0107] The tubular furnace roasting process in step A5 is divided into two steps: the roasting temperature is controlled at 550°C for 10h, and then the temperature is raised to 800°C for 10h.

[0108] According to the analysis and calculation, the purity of the lithium iron phosphate material prepared in this example is 99.2%.

[0109] Comparative Example 1

[0110] A method for recycling waste lithium iron phosphate battery materials, characterized in that it comprises the following steps:

[0111] A1: After discharging the waste lithium iron phosphate battery to a voltage not higher than 2.0V, it is disassembled and separated under an inert atmosphere, and the battery cell is collected separately;

[0112] A2: The battery cell is placed in a muffle furnace and calcined under an inert atmosphere for 3h, and after calcination, it is air-cooled to room temperature and mechanically crushed, and the lithium iron phosphate coarse powder, copper powder and aluminum powder are obtained by vibration screening;

[0113] A3: The lithium iron phosphate coarse powder is added to a sulfuric acid solution for heating leaching, and after filtration, an acid leaching solution and a filter residue are obtained, and the filter residue is dried to obtain high-carbon graphite;

[0114] A4: 4g of metal impurity adsorption resin is added to 100g of the acid leaching solution, stirred at 40°C for 100 minutes, and filtered;

[0115] A5: Lithium carbonate, ammonium dihydrogen phosphate, and ferrous oxalate are added to the filtrate, stirred uniformly and dried, ball milled to obtain a fine powder mixture, and the mixture is placed in a tubular furnace for roasting for 20h, and the sintered mixture is ground for 1h to obtain lithium iron phosphate powder.

[0116] The inert atmosphere in steps A1 and A2 is selected from nitrogen.

[0117] The calcination temperature in step A2 is 500°C.

[0118] The concentration of the sulfuric acid solution in step A3 is 18%, and the amount of the sulfuric acid solution is 4.5 times the amount of the lithium iron phosphate coarse powder.

[0119] The preparation of the metal impurity adsorption resin in step A4 comprises the following steps:

[0120] S1: Put 100g polystyrene macroporous sulfonic acid resin irradiation box under electron beam, electron beam energy 1.6MeV, dose rate 100Gy / s, radiation time 5min, stop irradiation after finishing, cool down, purge, then take out the irradiated polystyrene macroporous sulfonic acid resin;

[0121] S2: In a stirred tank, add 0.8g 5,5-divinyl-2,2-bipyridine, 1g initiator, 200g toluene, 20g irradiated polystyrene macroporous sulfonic acid resin into a closed stirred reaction kettle, purged with nitrogen, stirred at 80℃ for 10h, filter after reaction, dry to get metal impurity adsorption resin.

[0122] The initiator is selected from azobisisobutyronitrile.

[0123] The polystyrene macroporous sulfonic acid resin is a commercially available product, which is D001 resin.

[0124] The filtrate, lithium carbonate, ammonium dihydrogen phosphate and ferrous oxalate in step A5 are controlled in a molar ratio of n(Fe):n(Li):n(P)=1:1.03:1.03.

[0125] The tubular furnace roasting process in step A5 is divided into two steps: control the roasting temperature to 450℃ for 15h, and then increase the temperature to 700℃ for 15h.

[0126] After analysis and calculation, the purity of the lithium iron phosphate material prepared in this example is 96.4%.

[0127] Comparative Example 2

[0128] A method for recycling waste lithium iron phosphate battery materials, characterized in that it comprises the following steps:

[0129] A1: After discharging the waste lithium iron phosphate battery to a voltage not higher than 2.0V, disassembling and separating under inert atmosphere, and collecting the battery core alone;

[0130] A2: Put the battery core into a muffle furnace and calcine under inert atmosphere for 3h, mechanically crush after air cooling to room temperature after calcination, and separate by vibration screen to obtain lithium iron phosphate coarse powder, copper powder and aluminum powder;

[0131] A3: Add the lithium iron phosphate coarse powder into sulfuric acid solution for heating leaching, filter to obtain acid leaching liquid and filter residue, and dry the filter residue to obtain high-carbon graphite;

[0132] A4: Add 4g metal impurity adsorption resin into 100g acid leaching liquid, stir at 40℃ for 100min, and filter;

[0133] A5: adding lithium carbonate, ammonium dihydrogen phosphate, ferrous oxalate into the filtrate, stirring uniformly, drying, ball milling to obtain fine powder mixture, placing the mixture in a tube furnace for calcination for 20h, grinding the calcined mixture for 1h to obtain lithium iron phosphate powder.

[0134] The inert atmosphere in the steps A1 and A2 is selected from nitrogen.

[0135] The calcination temperature in the step A2 is 500℃.

[0136] The concentration of sulfuric acid solution in the step A3 is 18%, and the amount of sulfuric acid solution is 4.5 times of the crude lithium iron powder.

[0137] The metal impurity adsorption resin in the step A4 is prepared by the following steps:

[0138] S1: placing 100g polystyrene macroporous sulfonic acid resin in an irradiation box under electron beam, electron beam energy 1.6MeV, dose rate 100Gy / s, irradiation time 5min, stopping irradiation after completion, cooling, purging, and then taking out the irradiated polystyrene macroporous sulfonic acid resin;

[0139] S2: adding 0.1g tetrakis(4-boronic acid phenyl)ethylene, 1g initiator, 200g toluene, and 20g irradiated polystyrene macroporous sulfonic acid resin into a closed stirred reaction kettle, purging with nitrogen, stirring at 80℃ for 10h, filtering after reaction, drying to obtain metal impurity adsorption resin.

[0140] The initiator is selected from azobisisobutyronitrile.

[0141] The polystyrene macroporous sulfonic acid resin is a commercially available product, which is D001 resin.

[0142] The molar ratio of filtrate, lithium carbonate, ammonium dihydrogen phosphate, and ferrous oxalate in the step A5 is controlled to be n(Fe):n(Li):n(P)=1:1.03:1.03.

[0143] The tube furnace calcination process in the step A5 is divided into two steps: controlling the calcination temperature to be 450℃ for 15h, and then increasing the temperature to 700℃ for 15h.

[0144] According to the analysis and calculation, the purity of the lithium iron phosphate material prepared in this example is 97.1%.

[0145] The present application has been described in the foregoing by specific embodiments and examples, but these descriptions are only illustrative and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make various improvements, modifications or equivalent replacements to the technical solutions and embodiments of the present application without departing from the spirit and protection scope of the present application, and these shall fall within the protection scope of the present application.

Claims

1. A method for recycling waste lithium iron phosphate battery cell materials, characterized in that, Includes the following steps: A1: After discharging the waste lithium iron phosphate batteries to a voltage not higher than 2.0V, disassemble and separate them under an inert atmosphere, and collect the battery cells separately; A2: Place the battery cell in a muffle furnace and calcine it in an inert atmosphere for 3-5 hours. After calcination, air cool it to room temperature and then mechanically crush it. After being separated by a vibrating sieve, lithium iron phosphate coarse powder, copper powder and aluminum powder are obtained. A3: Add crude lithium iron phosphate powder to sulfuric acid solution, heat and leach, filter to obtain acid leaching solution and filter residue, and dry the filter residue to obtain high carbon graphite. A4: By weight, add 4-8 parts of metal impurity adsorption resin to 100-140 parts of acid leaching solution, stir at 40-50℃ for 50-100 minutes, and filter. A5: Add lithium carbonate, ammonium dihydrogen phosphate, and ferrous oxalate to the filtrate, stir evenly and dry, ball mill to obtain a fine powder mixture, place the mixture in a tube furnace for calcination for 20-30 hours, and after sintering, grind the mixture for 1-2 hours to obtain lithium iron phosphate powder. The preparation of the metal impurity adsorption resin in step A4 includes the following steps: S1: By weight, place 100-200 parts of polystyrene macroporous sulfonic acid resin into an irradiation box and irradiate it under an electron beam. The electron beam energy is 1.6 MeV, the dose rate is 100-500 Gy / s, and the irradiation time is 5-15 min. After the irradiation is completed, stop the irradiation, cool it down, purge it, and then take out the irradiated polystyrene macroporous sulfonic acid resin. S2: Add 0.05-0.5 parts tetra(4-boratephenyl)ethylene, 0.8-2 parts 5,5-divinyl-2,2-bipyridine, 1-3 parts initiator, 200-300 parts toluene, and 20-40 parts irradiated polystyrene macroporous sulfonic acid resin to a sealed stirred reactor, purge with nitrogen, and stir at 80-100℃ for 10-15 h. After the reaction is complete, filter and dry to obtain metal impurity adsorption resin. The initiator is selected from at least one of azobisisobutyronitrile, azobisisoheptanenitrile, and benzoyl peroxide.

2. The method for recycling waste lithium iron phosphate battery cell materials according to claim 1, characterized in that, In steps A1 and A2, the inert atmosphere is selected from at least one of nitrogen, helium, or argon.

3. The method for recycling waste lithium iron phosphate battery cell materials according to claim 1, characterized in that, The calcination temperature in step A2 is 500-750℃.

4. The method for recycling waste lithium iron phosphate battery cell materials according to claim 1, characterized in that, In step A3, the concentration of the sulfuric acid solution is 18-32%, and the amount of sulfuric acid solution is 1.5-4.5 times that of the crude lithium iron phosphate powder.

5. The method for recycling waste lithium iron phosphate battery cell materials according to claim 1, characterized in that, In step A5, the molar ratio of filtrate, lithium carbonate, ammonium dihydrogen phosphate, and ferrous oxalate is controlled as n(Fe):n(Li):n(P) = 1:1.01-1.08:1.01-1.

08.

6. The method for recycling waste lithium iron phosphate battery cell materials according to claim 1, characterized in that, The tube furnace roasting process in step A5 consists of two steps: controlling the roasting temperature at 450-550℃ for 10-15 hours, and then raising the temperature to 700-800℃ for 10-15 hours.