Method for separating and recycling waste lithium iron phosphate-nickel cobalt manganese lithium mixed positive electrode material

Abstract

The application provides a method for selectively separating and recycling waste battery lithium iron phosphate-lithium nickel cobalt manganese oxide mixed positive electrode material, which comprises the following steps: preparing lithium cobalt oxide and lithium iron phosphate mixed positive electrode powder from waste lithium cobalt oxide batteries and waste lithium iron phosphate batteries, adding acid leaching solution to obtain lithium nickel cobalt manganese oxide leaching solution and lithium iron phosphate leaching residue; adding sodium hydroxide aqueous solution and ammonia solution to the lithium nickel cobalt manganese oxide leaching solution for co-precipitation to obtain a second filtrate and precipitate; preparing the precipitate into a lithium nickel cobalt manganese precursor, then adding lithium source to prepare regenerated lithium nickel cobalt manganese oxide positive electrode material; adding carbonate aqueous solution to the second filtrate to prepare lithium carbonate crystals; and adding lithium source to the lithium iron phosphate leaching residue to prepare regenerated lithium iron phosphate positive electrode material. The method has the advantages of simple process, selective separation and efficient recovery of waste lithium cobalt oxide material and waste lithium iron phosphate material, low cost, high recovery rate and wide industrial application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of waste battery recycling, and particularly relates to a method for selectively separating and recycling mixed positive electrode materials of waste lithium iron phosphate-lithium nickel cobalt manganese oxide. BACKGROUND

[0002] Lithium iron phosphate (LFP) and ternary materials (NCM) form a "double dominant" market pattern due to their complementary performance. As of 2023, LFP batteries have broken through 60% in the power and energy storage fields due to their low cost and high safety, while ternary materials still occupy the high-end market with the advantage of high energy density, and the proportion of LFP and NCM exceeds 80%. Therefore, recycling and utilizing retired batteries dominated by LFP and NCM is the demand for ensuring metal resource supply and realizing green and sustainable development.

[0003] Currently, the recycling technology route for retired batteries is mainly designed for a single positive electrode system: LFP recycling needs to destroy its stable Fe-P-O structure under high temperature conditions through the combination of strong acid and oxidizing agent (hydrogen peroxide), and then leach lithium, iron, phosphorus and other elements in LFP into liquid phase, and then precipitate step by step by adjusting pH value; ternary material recycling relies on strong acid and reducing agent (such as Na2S2O3) assisted leaching, and separates nickel, cobalt, manganese and other metals through multi-stage solvent extraction. The current single recycling method does not meet the current situation of diversified battery layout in China, resulting in complex and lengthy process flow, high recycling cost, and difficulty in balancing economy and environmental protection. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a method for selectively separating and recycling mixed positive electrode materials of waste lithium iron phosphate-lithium nickel cobalt manganese oxide, which has the advantages of simple process, selective separation and efficient recovery of waste lithium cobalt oxide material and waste lithium iron phosphate material, low cost, high recovery rate, and wide industrial application prospect.

[0005] To solve the above technical problems, the technical solution adopted by the present application is: a method for selectively separating and recycling mixed positive electrode materials of waste lithium iron phosphate-lithium nickel cobalt manganese oxide, which comprises the following steps:

[0006] S1, discharging the waste lithium cobalt oxide battery and the waste lithium iron phosphate battery in a saturated sodium chloride solution, disassembling and separating the positive electrode sheet, cutting into fragments, pretreating, and obtaining mixed positive electrode powder of lithium cobalt oxide and lithium iron phosphate;

[0007] S2, adding an acid leaching solution to the mixed cathode powder of lithium cobalt oxide and lithium iron phosphate obtained in S1, stirring and reacting at a temperature of 50-60 DEG C for 10-240 min, naturally cooling to room temperature, and then filtering to obtain a lithium nickel cobalt manganese oxide leaching solution and a lithium iron phosphate leaching residue, respectively;

[0008] S3, adding a sodium hydroxide aqueous solution and an ammonia aqueous solution to the lithium nickel cobalt manganese oxide leaching solution obtained in S2 for co-precipitation, filtering to obtain a second filtrate and a precipitate, respectively, and drying the precipitate at a temperature of 60-100 DEG C to obtain a nickel cobalt manganese precursor;

[0009] S4, adding a lithium source to the nickel cobalt manganese precursor obtained in S3, uniformly mixing, ball-milling, and drying to obtain a mixed powder A, heating the mixed powder A from room temperature to 400-900 DEG C at a heating rate of 5 DEG C / min under an inert atmosphere, and isothermally calcining for 3-20 h to obtain a regenerated lithium nickel cobalt manganese oxide cathode material after naturally cooling to room temperature;

[0010] S5, adding a carbonate aqueous solution to the second filtrate obtained in S3, heating and concentrating at a temperature of 95 DEG C for 2-5 h to obtain lithium carbonate crystals;

[0011] S6, adding a lithium source to the lithium iron phosphate leaching residue obtained in S2, uniformly mixing, ball-milling, and drying to obtain a mixed powder B, heating the mixed powder B from room temperature to 400-900 DEG C at a heating rate of 5 DEG C / min under an inert atmosphere, and isothermally calcining for 3-20 h to obtain a regenerated lithium iron phosphate cathode material after naturally cooling to room temperature.

[0012] Preferably, the discharging treatment in S1 is performed for 24 h, and the size of the fragments is 2 cm x 2 cm; the pre-treatment method is soaking and dissolving the aluminum foil in a sodium hydroxide aqueous solution with a concentration of 0.1-2 mol / L, and then filtering, washing with water, and drying to obtain the mixed cathode powder of lithium cobalt oxide and lithium iron phosphate.

[0013] Preferably, the concentration of the acid leaching solution in S2 is 0.1-2 mol / L; the acid leaching solution is a hydrochloric acid solution, a sulfuric acid solution, a nitric acid solution, a lactic acid solution, an oxalic acid solution, a malic acid solution, a citric acid solution, a tartaric acid solution, a gluconic acid solution, or an ascorbic acid solution; the amount ratio of the mixed cathode powder of lithium cobalt oxide and lithium iron phosphate to the acid leaching solution is 1 g to (10-60) mL; and the stirring rate of the stirring reaction is 800 r / min.

[0014] Preferably, the mass ratio of the nickel-cobalt-manganese lithium acid acid acid, the aqueous sodium hydroxide solution and the aqueous ammonia solution in S3 is 1.0: (0.2-1.0): (0.2-1.0); the aqueous sodium hydroxide solution is an aqueous sodium hydroxide solution with a concentration of 0.1 mol / L-2 mol / L, and the aqueous ammonia solution is an aqueous ammonia solution with a concentration of 1 mol / L-5 mol / L.

[0015] Preferably, the lithium source in the nickel-cobalt-manganese precursor in S4 is added according to a molar ratio of 1: (1-1.2) of the total moles of nickel, cobalt and manganese elements to the moles of lithium element; and the lithium source is lithium carbonate.

[0016] Preferably, the concentration of the aqueous carbonate salt solution in S5 is 0.5 mol / L-3 mol / L; the carbonate salt in the aqueous carbonate salt solution is sodium carbonate, ammonium carbonate, sodium bicarbonate or ammonium bicarbonate; and the use amount ratio of the second filtrate to the aqueous carbonate salt solution is (20-100) mL: 50 mL.

[0017] Preferably, the lithium source in the lithium iron phosphate leaching residue in S6 is added according to a molar ratio of 1: (1-1.2) of the moles of iron element to the moles of lithium element; and the lithium source is lithium carbonate.

[0018] The present application is not limited to lithium iron phosphate and nickel-cobalt-manganese lithium battery for the positive electrode material, but also includes lithium manganate, lithium cobaltate, lithium titanate and other batteries, and the nickel-cobalt-manganese lithium battery includes NCM523, NCM622, NCM811 and the like.

[0019] Compared with the prior art, the present application has the following advantages:

[0020] 1. The process is simple, and can realize selective separation and efficient recovery of waste lithium cobaltate material and waste lithium iron phosphate material, has the advantages of low cost, high recovery rate and wide industrial application prospect.

[0021] 2. The method for selectively separating and recovering waste battery lithium iron phosphate-nickel cobalt manganese lithium mixed positive material breaks through the traditional single positive material recovery concept, meets the green and innovative development needs of comprehensive utilization of solid waste, provides a new solution for diversified, resourceful and harmless recovery of retired lithium ion batteries, alleviates the problems of environmental pollution and metal resource shortage, and promotes the sustainable development of new energy industry.

[0022] The present application will be further described in detail below in conjunction with examples. DETAILED DESCRIPTION

[0023] Example 1

[0024] The method for selectively separating and recovering waste battery lithium iron phosphate-nickel cobalt manganese lithium mixed positive material of the present embodiment is as follows:

[0025] S1, disassembling and separating the positive plate after discharging treatment of waste lithium cobalt oxide battery and waste lithium iron phosphate battery in saturated sodium chloride solution for 24h, cutting into fragments with a size of 2cm*2cm, and obtaining mixed positive electrode powder of lithium cobalt oxide and lithium iron phosphate after pretreatment;

[0026] The pretreatment method is: soaking and dissolving the aluminum foil in a 1mol / L sodium hydroxide aqueous solution, then filtering, washing with water, and drying to obtain the mixed positive electrode powder of lithium cobalt oxide and lithium iron phosphate;

[0027] The mass fraction of the following elements in the lithium cobalt oxide (LCO) positive electrode powder is: Li 3.85%, Co 63.64%;

[0028] The mass fraction of the following elements in the lithium iron phosphate (LFP) positive electrode powder is: Li 3.09%, Fe 34.56%, P 19.71%;

[0029] The molar ratio of lithium cobalt oxide to lithium iron phosphate in the mixed positive electrode powder of lithium cobalt oxide and lithium iron phosphate of the embodiment is 1:1;

[0030] S2, adding an acid leaching solution (a 1.5mol / L lactic acid solution) to the mixed positive electrode powder of lithium cobalt oxide and lithium iron phosphate obtained in S1, stirring at a temperature of 50℃ and a stirring rate of 800r / min for 60min, naturally cooling to room temperature, and filtering to obtain a lithium nickel cobalt manganese oxide leaching solution and a lithium iron phosphate leaching residue, respectively; the use amount ratio of the mixed positive electrode powder of lithium cobalt oxide and lithium iron phosphate to the acid leaching solution is 1g:40mL;

[0031] The cobalt leaching rate in the mixed positive electrode material is 99.6% measured by ICP-OES, the nickel leaching selectivity reaches 99.7%, the manganese leaching rate reaches 99.5%, and the iron ion leaching rate in the leaching solution is only 0.2%, so the lithium nickel cobalt manganese oxide leaching solution and the lithium iron phosphate leaching residue are subjected to separate regeneration treatment;

[0032] S3, adding a 1.5mol / L sodium hydroxide aqueous solution and a 1.5mol / L ammonia solution to the lithium nickel cobalt manganese oxide leaching solution obtained in S2 for co-precipitation, filtering to obtain a second filtrate and a precipitate, respectively; drying the precipitate at a temperature of 80℃ to obtain a nickel cobalt manganese precursor; the mass ratio of the lithium nickel cobalt manganese oxide leaching solution, the sodium hydroxide aqueous solution, and the ammonia solution is 1.0:0.5:0.5;

[0033] S4. Add lithium source (lithium carbonate) to the nickel-cobalt-manganese precursor obtained in S3, mix evenly, ball mill and dry to obtain mixed powder A; under inert atmosphere protection, heat the mixed powder A from room temperature to 850°C at a heating rate of 5°C / min, calcine at a constant temperature for 10 hours, and then cool naturally to room temperature to obtain regenerated nickel-cobalt-manganese lithium oxide cathode material; the lithium source is added to the nickel-cobalt-manganese precursor according to the total molar ratio of nickel, cobalt, and manganese elements to lithium element of 1:1.1;

[0034] S5. Add 50 mL of carbonate aqueous solution (2 mol / L sodium carbonate aqueous solution) to 40 mL of the second filtrate obtained from S3, and heat and concentrate at 95 °C for 2 h to obtain lithium carbonate crystals.

[0035] S6. Add lithium source (lithium carbonate) to the lithium iron phosphate leaching residue obtained in S2, mix evenly, ball mill and dry to obtain mixed powder B; under inert atmosphere protection, heat the mixed powder B from room temperature to 750°C at a heating rate of 5°C / min, calcine at a constant temperature for 8 hours, and then cool naturally to room temperature to obtain regenerated lithium iron phosphate cathode material; the lithium source is added to the lithium iron phosphate leaching residue according to the molar ratio of iron to lithium of 1:1.1.

[0036] Example 2

[0037] The method for selectively separating and recycling mixed cathode materials of lithium iron phosphate and lithium nickel cobalt manganese oxide batteries in this embodiment is as follows:

[0038] S1. After discharging waste lithium cobalt oxide batteries and waste lithium iron phosphate batteries in a saturated sodium chloride solution for 24 hours, the positive electrode sheets are disassembled and separated, cut into fragments of size 2cm×2cm, and after pretreatment, a mixed positive electrode powder of lithium cobalt oxide and lithium iron phosphate is obtained.

[0039] The pretreatment method is as follows: the fragments are soaked in a 2 mol / L sodium hydroxide aqueous solution to dissolve the aluminum foil, and then filtered, washed with water and dried to obtain a mixed positive electrode powder of lithium cobalt oxide and lithium iron phosphate.

[0040] The mass fractions of the following elements in lithium cobalt oxide (LCO) cathode powder are: Li 3.85%, Co 63.64%;

[0041] The mass fractions of the following elements in lithium iron phosphate (LFP) cathode powder are: Li 3.09%, Fe 34.56%, P 19.71%;

[0042] In this embodiment, the molar ratio of lithium cobalt oxide to lithium iron phosphate in the mixed cathode powder of lithium cobalt oxide and lithium iron phosphate is 2:1.

[0043] S2. Add an acid leaching solution (2 mol / L citric acid solution) to the mixed cathode powder of lithium cobalt oxide and lithium iron phosphate obtained in S1. Stir and react for 240 min at a temperature of 60℃ and a stirring rate of 800 r / min. After naturally cooling to room temperature, filter to obtain lithium nickel cobalt manganese oxide leaching solution and lithium iron phosphate leaching residue, respectively. The ratio of the mixed cathode powder of lithium cobalt oxide and lithium iron phosphate to the acid leaching solution is 1 g: 60 mL.

[0044] The cobalt leaching rate in the mixed cathode material was 99.4%, the nickel leaching selectivity was 99.5%, the manganese leaching rate was 99.7%, and the iron ion leaching rate in the leachate was only 0.8%. Therefore, the lithium nickel cobalt manganese oxide leachate and the lithium iron phosphate leaching residue were regenerated separately.

[0045] S3. Add a 2 mol / L sodium hydroxide aqueous solution and a 2.5 mol / L ammonia aqueous solution to the lithium nickel cobalt manganese oxide leaching solution obtained in S2 for co-precipitation. After filtration, a second filtrate and a precipitate are obtained respectively. The precipitate is dried at a temperature of 90°C to obtain the nickel cobalt manganese precursor. The mass ratio of the lithium nickel cobalt manganese oxide leaching solution, sodium hydroxide aqueous solution, and ammonia aqueous solution is 1.0:0.4:0.8.

[0046] S4. Add lithium source (lithium carbonate) to the nickel-cobalt-manganese precursor obtained in S3, mix evenly, ball mill and dry to obtain mixed powder A; under inert atmosphere protection, heat the mixed powder A from room temperature to 900℃ at a heating rate of 5℃ / min, calcine at a constant temperature for 3h, and then cool naturally to room temperature to obtain regenerated nickel-cobalt-manganese lithium oxide cathode material; the lithium source is added to the nickel-cobalt-manganese precursor according to the total molar ratio of nickel, cobalt, and manganese elements to lithium element of 1:1.2;

[0047] S5. Add 50 mL of carbonate aqueous solution (3 mol / L ammonium carbonate aqueous solution) to 50 mL of the second filtrate obtained from S3, and heat and concentrate at 95℃ for 2 h to obtain lithium carbonate crystals.

[0048] S6. Add lithium source (lithium carbonate) to the lithium iron phosphate leaching residue obtained in S2, mix evenly, ball mill and dry to obtain mixed powder B; under inert atmosphere protection, heat the mixed powder B from room temperature to 900℃ at a heating rate of 5℃ / min, calcine at a constant temperature for 3h, and then cool naturally to room temperature to obtain regenerated lithium iron phosphate cathode material; the lithium source is added to the lithium iron phosphate leaching residue according to the molar ratio of iron to lithium of 1:1.2.

[0049] Example 3

[0050] The method for selectively separating and recycling mixed cathode materials of lithium iron phosphate and lithium nickel cobalt manganese oxide batteries in this embodiment is as follows:

[0051] S1. After discharging waste lithium cobalt oxide batteries and waste lithium iron phosphate batteries in a saturated sodium chloride solution for 24 hours, the positive electrode sheets are disassembled and separated, cut into fragments of size 2cm×2cm, and after pretreatment, a mixed positive electrode powder of lithium cobalt oxide and lithium iron phosphate is obtained.

[0052] The pretreatment method is as follows: the fragments are soaked in a 0.1 mol / L sodium hydroxide aqueous solution to dissolve the aluminum foil, and then filtered, washed with water and dried to obtain a mixed positive electrode powder of lithium cobalt oxide and lithium iron phosphate.

[0053] The mass fractions of the following elements in lithium cobalt oxide (LCO) cathode powder are: Li 3.85%, Co 63.64%;

[0054] The mass fractions of the following elements in lithium iron phosphate (LFP) cathode powder are: Li 3.09%, Fe 34.56%, P 19.71%;

[0055] In this embodiment, the molar ratio of lithium cobalt oxide to lithium iron phosphate in the mixed cathode powder of lithium cobalt oxide and lithium iron phosphate is 5:1.

[0056] S2. An acid leaching solution (0.1 mol / L malic acid solution) is added to the mixed cathode powder of lithium cobalt oxide and lithium iron phosphate obtained in S1. The mixture is stirred and reacted for 10 min at a temperature of 55°C and a stirring rate of 800 r / min. After naturally cooling to room temperature, the mixture is filtered to obtain lithium nickel cobalt manganese oxide leaching solution and lithium iron phosphate leaching residue, respectively. The ratio of the mixed cathode powder of lithium cobalt oxide and lithium iron phosphate to the acid leaching solution is 1 g: 10 mL.

[0057] The cobalt leaching rate in the mixed cathode material was 92.3%, the nickel leaching selectivity was 96.5%, the manganese leaching rate was 93.1%, and the iron ion leaching rate in the leachate was only 0.9%. Therefore, the lithium nickel cobalt manganese oxide leaching solution and the lithium iron phosphate leaching residue were regenerated separately.

[0058] S3. Add a 0.1 mol / L sodium hydroxide aqueous solution and a 1 mol / L ammonia aqueous solution to the lithium nickel cobalt manganese oxide leaching solution obtained in S2 for co-precipitation. After filtration, a second filtrate and a precipitate are obtained respectively. The precipitate is dried at a temperature of 60°C to obtain the nickel cobalt manganese precursor. The mass ratio of the lithium nickel cobalt manganese oxide leaching solution, sodium hydroxide aqueous solution, and ammonia aqueous solution is 1.0:0.2:0.2.

[0059] S4. Add lithium source (lithium carbonate) to the nickel-cobalt-manganese precursor obtained in S3, mix evenly, ball mill and dry to obtain mixed powder A; under inert atmosphere protection, heat the mixed powder A from room temperature to 400℃ at a heating rate of 5℃ / min, calcine at a constant temperature for 20h, and then cool naturally to room temperature to obtain regenerated nickel-cobalt-manganese lithium oxide cathode material; the lithium source is added to the nickel-cobalt-manganese precursor according to the total molar ratio of nickel, cobalt, and manganese elements to lithium element of 1:1;

[0060] S5. Add 50 mL of carbonate aqueous solution (0.5 mol / L sodium bicarbonate aqueous solution) to 20 mL of the second filtrate obtained from S3, and heat and concentrate at 95 °C for 5 h to obtain lithium carbonate crystals.

[0061] S6. Add lithium source (lithium carbonate) to the lithium iron phosphate leaching residue obtained in S2, mix evenly, ball mill and dry to obtain mixed powder B; under inert atmosphere protection, heat the mixed powder B from room temperature to 400°C at a heating rate of 5°C / min, calcine at a constant temperature for 20 hours, and then cool naturally to room temperature to obtain regenerated lithium iron phosphate cathode material; the lithium source is added to the lithium iron phosphate leaching residue according to a molar ratio of iron to lithium of 1:1.

[0062] Example 4

[0063] The method for selectively separating and recycling mixed cathode materials of lithium iron phosphate and lithium nickel cobalt manganese oxide batteries in this embodiment is as follows:

[0064] S1. After discharging waste lithium cobalt oxide batteries and waste lithium iron phosphate batteries in a saturated sodium chloride solution for 24 hours, the positive electrode sheets are disassembled and separated, cut into fragments of size 2cm×2cm, and after pretreatment, a mixed positive electrode powder of lithium cobalt oxide and lithium iron phosphate is obtained.

[0065] The pretreatment method is as follows: the fragments are soaked in a 1 mol / L sodium hydroxide aqueous solution to dissolve the aluminum foil, and then filtered, washed with water and dried to obtain a mixed positive electrode powder of lithium cobalt oxide and lithium iron phosphate.

[0066] The mass fractions of the following elements in lithium cobalt oxide (LCO) cathode powder are: Li 3.85%, Co 63.64%;

[0067] The mass fractions of the following elements in lithium iron phosphate (LFP) cathode powder are: Li 3.09%, Fe 34.56%, P 19.71%;

[0068] In this embodiment, the molar ratio of lithium cobalt oxide to lithium iron phosphate in the mixed cathode powder of lithium cobalt oxide and lithium iron phosphate is 3:1.

[0069] S2. An acid leaching solution (1 mol / L tartaric acid solution) is added to the mixed cathode powder of lithium cobalt oxide and lithium iron phosphate obtained in S1. The mixture is stirred and reacted for 120 min at a temperature of 50°C and a stirring rate of 800 r / min. After naturally cooling to room temperature, the mixture is filtered to obtain lithium nickel cobalt manganese oxide leaching solution and lithium iron phosphate leaching residue, respectively. The ratio of the mixed cathode powder of lithium cobalt oxide and lithium iron phosphate to the acid leaching solution is 1 g: 30 mL.

[0070] The acid leaching solution in this embodiment can also be hydrochloric acid solution, sulfuric acid solution, nitric acid solution, oxalic acid solution, gluconic acid solution, or ascorbic acid solution;

[0071] The cobalt leaching rate in the mixed cathode material was 98.8%, the nickel leaching selectivity was 98.5%, the manganese leaching rate was 98.7%, and the iron ion leaching rate in the leachate was only 0.5%. Therefore, the lithium nickel cobalt manganese oxide leachate and the lithium iron phosphate leaching residue were regenerated separately.

[0072] S3. Add a 1 mol / L sodium hydroxide aqueous solution and a 5 mol / L ammonia aqueous solution to the lithium nickel cobalt manganese oxide leaching solution obtained in S2 for co-precipitation. After filtration, a second filtrate and a precipitate are obtained respectively. The precipitate is dried at 100°C to obtain the nickel cobalt manganese precursor. The mass ratio of the lithium nickel cobalt manganese oxide leaching solution, sodium hydroxide aqueous solution, and ammonia aqueous solution is 1.0 : 1.0 : 1.0.

[0073] S4. Add lithium source (lithium carbonate) to the nickel-cobalt-manganese precursor obtained in S3, mix evenly, ball mill and dry to obtain mixed powder A; under inert atmosphere protection, heat the mixed powder A from room temperature to 600℃ at a heating rate of 5℃ / min, calcine at a constant temperature for 10h, and then cool naturally to room temperature to obtain regenerated nickel-cobalt-manganese lithium oxide cathode material; the lithium source is added to the nickel-cobalt-manganese precursor according to the total molar ratio of nickel, cobalt, and manganese elements to lithium element of 1:1.

[0074] S5. Add 50 mL of carbonate aqueous solution (2 mol / L ammonium bicarbonate aqueous solution) to 100 mL of the second filtrate obtained from S3, and heat and concentrate at 95 °C for 3 h to obtain lithium carbonate crystals.

[0075] S6. Add lithium source (lithium carbonate) to the lithium iron phosphate leaching residue obtained in S2, mix evenly, ball mill and dry to obtain mixed powder B; under inert atmosphere protection, heat the mixed powder B from room temperature to 600℃ at a heating rate of 5℃ / min, calcine at a constant temperature for 10h, and then cool naturally to room temperature to obtain regenerated lithium iron phosphate cathode material; the lithium source is added to the lithium iron phosphate leaching residue according to a molar ratio of iron to lithium of 1:1.

[0076] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A method for selectively separating and recycling mixed cathode materials of lithium iron phosphate and lithium nickel cobalt manganese oxide from waste batteries, characterized in that, The method is as follows: S1. After discharging waste lithium cobalt oxide batteries and waste lithium iron phosphate batteries in a saturated sodium chloride solution, the positive electrode sheets are disassembled and separated, cut into fragments, and pretreated to obtain a mixed positive electrode powder of lithium cobalt oxide and lithium iron phosphate. S2. Add acid leaching solution to the mixed positive electrode powder of lithium cobalt oxide and lithium iron phosphate obtained in S1, stir and react at a temperature of 50℃~60℃ for 10min~240min, cool naturally to room temperature, filter, and obtain lithium nickel cobalt manganese oxide leaching solution and lithium iron phosphate leaching residue respectively. S3. Add sodium hydroxide aqueous solution and ammonia aqueous solution to the lithium nickel cobalt manganese oxide leaching solution obtained in S2 for co-precipitation. After filtration, the second filtrate and precipitate are obtained respectively. The precipitate was dried at a temperature of 60℃ to 100℃ to obtain a nickel-cobalt-manganese precursor. S4. Add a lithium source to the nickel-cobalt-manganese precursor obtained in S3, mix evenly, ball mill and dry to obtain mixed powder A; under inert atmosphere protection, heat the mixed powder A from room temperature to 400℃~900℃ at a heating rate of 5℃ / min, calcine at a constant temperature for 3h~20h, and then cool naturally to room temperature to obtain recycled nickel-cobalt-manganese lithium oxide cathode material. S5. Add an aqueous solution of carbonate to the second filtrate obtained in S3, and heat and concentrate at 95°C for 2 to 5 hours to obtain lithium carbonate crystals. S6. Add lithium source to the lithium iron phosphate leaching residue obtained in S2, mix evenly, ball mill and dry to obtain mixed powder B; under inert atmosphere protection, heat the mixed powder B from room temperature to 400℃~900℃ at a heating rate of 5℃ / min, calcine at a constant temperature for 3h~20h, and then cool naturally to room temperature to obtain regenerated lithium iron phosphate cathode material.

2. The method for selective separation and recycling of mixed cathode materials of lithium iron phosphate and lithium nickel cobalt manganese oxide from waste batteries according to claim 1, characterized in that, The discharge treatment time in S1 is 24 hours; the size of the fragment is 2cm×2cm; the pretreatment method is as follows: the fragment is soaked in a sodium hydroxide aqueous solution with a concentration of 0.1mol / L to 2mol / L to dissolve aluminum foil, and then filtered, washed with water and dried to obtain a mixed positive electrode powder of lithium cobalt oxide and lithium iron phosphate.

3. The method for selective separation and recycling of mixed cathode materials of lithium iron phosphate and lithium nickel cobalt manganese oxide from waste batteries according to claim 1, characterized in that, The concentration of the acid leaching solution in S2 is 0.1 mol / L to 2 mol / L; the acid leaching solution is hydrochloric acid solution, sulfuric acid solution, nitric acid solution, lactic acid solution, oxalic acid solution, malic acid solution, citric acid solution, tartaric acid solution, gluconic acid solution, or ascorbic acid solution; the ratio of the mixed positive electrode powder of lithium cobalt oxide and lithium iron phosphate to the acid leaching solution is 1 g: (10-60) mL; the stirring rate of the stirring reaction is 800 r / min.

4. The method for selective separation and recycling of mixed cathode materials of lithium iron phosphate and lithium nickel cobalt manganese oxide from waste batteries according to claim 1, characterized in that, The mass ratio of the lithium nickel cobalt manganese oxide leaching solution, the sodium hydroxide aqueous solution, and the ammonia aqueous solution in S3 is 1.0 : (0.2~1.0) : (0.2~1.0); the sodium hydroxide aqueous solution is a sodium hydroxide aqueous solution with a concentration of 0.1mol / L~2mol / L, and the ammonia aqueous solution is an ammonia aqueous solution with a concentration of 1mol / L~5mol / L.

5. The method for selective separation and recycling of mixed cathode materials of lithium iron phosphate and lithium nickel cobalt manganese oxide from waste batteries according to claim 1, characterized in that, In S4, the lithium source is added to the nickel-cobalt-manganese precursor according to the total molar ratio of nickel, cobalt, and manganese to lithium of 1:(1-1.2); the lithium source is lithium carbonate.

6. The method for selective separation and recycling of mixed cathode materials of lithium iron phosphate and lithium nickel cobalt manganese oxide from waste batteries according to claim 1, characterized in that, The concentration of the carbonate aqueous solution in S5 is 0.5 mol / L to 3 mol / L; the carbonate in the carbonate aqueous solution is sodium carbonate, ammonium carbonate, sodium bicarbonate or ammonium bicarbonate; the ratio of the second filtrate to the carbonate aqueous solution is (20 to 100) mL: 50 mL.

7. The method for selective separation and recycling of mixed cathode materials of lithium iron phosphate and lithium nickel cobalt manganese oxide from waste batteries according to claim 1, characterized in that, The lithium source in S6 is added to the lithium iron phosphate leaching residue according to the molar ratio of iron to lithium of 1:(1~1.2); the lithium source is lithium carbonate.