Method for strengthening recovery of waste lithium iron phosphate material by using waste lithium cobalt oxide as oxidizing agent

Abstract

The invention provides a method for strengthening recovery of a waste lithium iron phosphate material by using waste lithium cobalt oxide as an oxidizing agent. The method comprises the following steps: discharging and disassembling waste lithium iron phosphate and lithium cobalt oxide batteries to obtain positive plates; dissolving aluminum foil in the positive plate in a sodium hydroxide alkaline leaching solution to obtain lithium iron phosphate and lithium cobalt oxide positive electrode powder; the method comprises the following steps: leaching lithium iron phosphate positive electrode powder by adopting a deep-eutectic solvent, and meanwhile, realizing an enhanced leaching process by taking lithium cobalt oxide positive electrode powder as an oxidizing agent; and carrying out coordination separation and photo-reduction separation on the completely leached solution to realize selective recovery of cobalt, iron, phosphorus and lithium. According to the method, the oxidation-reduction capacity of the material is fully utilized to strengthen the leaching process, efficient recovery of valuable elements in the waste positive electrode material is achieved, and additional addition of an oxidizing agent and a reducing agent is avoided. The method can achieve the purposes of synergistic enhanced leaching and selective separation of the waste lithium cobalt oxide material and the waste lithium iron phosphate material, and is low in cost, high in recovery rate and wide in industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of waste lithium iron phosphate material recycling technology, specifically relating to a method for enhancing the recycling of waste lithium iron phosphate materials by using waste lithium cobalt oxide as an oxidant. Background Technology

[0002] With the explosive growth of the new energy vehicle and energy storage industries, lithium iron phosphate (LiFePO4) batteries have become the mainstream choice in the power battery market due to their high safety, long cycle life, and low cost. However, the lifespan of power batteries is only 3 to 8 years, and the boom in the new energy industry also means the generation of a large number of waste batteries, which pose a serious threat to the environment and cause a large waste of resources. Therefore, the need for efficient recycling of retired lithium iron phosphate batteries has become extremely urgent.

[0003] As an important "urban mine," waste lithium iron phosphate (LFP) has made progress in large-scale processing, but many limitations remain. LFP cathode materials do not contain precious metals such as cobalt and nickel, and their lithium content (approximately 4%) is significantly lower than cobalt-based cathode materials (such as NCM, which contains about 7%). Traditional wet recycling yields a profit of only 2,000-5,000 yuan per ton, far lower than that of waste ternary lithium batteries and lithium cobalt oxide batteries. LFP has a very stable crystal structure, and the recycling process often requires strong acids (such as H₂SO₄) and oxidants (H₂O₂) at high temperatures (60-90°C) to break the Fe-OP bonds and release Li⁺. However, the high-temperature, strong acid recycling process also generates waste gas, wastewater, and waste residue, exacerbating pollution problems. Furthermore, the use of large amounts of hydrogen peroxide increases operating costs. Therefore, current waste lithium iron phosphate recycling efforts are mainly characterized by high recycling costs and environmental pollution, resulting in poor overall economic benefits.

[0004] Oxidation of lithium iron phosphate is key to improving leaching efficiency. The Fe in lithium iron phosphate... 2 ⁺ needs to be oxidized to Fe 3 ⁺ This weakens the Fe-PO4 bond, thereby promoting lithium release. Currently, oxidants such as H2O2, sodium persulfate (Na2S2O8), and O3 suffer from high cost and storage difficulties. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for enhancing the recycling of waste lithium iron phosphate materials by using waste lithium cobalt oxide as an oxidant, which addresses the shortcomings of the prior art. This method is simple and can achieve the purpose of synergistic enhanced leaching and selective separation of waste lithium cobalt oxide and waste lithium iron phosphate materials. It has the advantages of low cost, high recovery rate and extremely broad prospects for industrial application.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for enhancing the recycling of waste lithium iron phosphate materials by using waste lithium cobalt oxide as an oxidant, the method being as follows: S1. After discharging the waste lithium cobalt oxide batteries, disassemble them using physical methods to obtain lithium cobalt oxide positive electrode sheets. After pretreatment, lithium cobalt oxide positive electrode powder is obtained. Waste lithium iron phosphate batteries are discharged and disassembled using physical methods to obtain lithium iron phosphate positive electrode sheets. After pretreatment, lithium iron phosphate positive electrode powder is obtained. S2. Mix the lithium cobalt oxide cathode powder and lithium iron phosphate cathode powder obtained in S1 evenly to obtain a mixed cathode powder. S3. After the hydrogen bond donor and hydrogen bond acceptor are mixed evenly, the mixture is magnetically stirred for 5 min to 60 min at a temperature of 50℃~100℃ and a rotation speed of 800 r / min~1000 r / min, and then naturally cooled to room temperature to obtain a eutectic solvent. S4. Add the mixed positive electrode powder obtained in S2 to the eutectic solvent obtained in S3, and stir the reaction at a temperature of 25℃~200℃ for 20min~60min to obtain the leaching solution. S5. Add a coordination modifier to the leaching solution obtained in S4, stir for 5 min to 10 min, filter to obtain filtrate a, and dry the remaining filter residue to obtain a cobalt-containing precipitate. S6. The filtrate a obtained in S5 is subjected to photoreduction treatment for 20 min to 30 min while stirring. After filtration, filtrate b is obtained. The remaining filter residue is dried to obtain an iron-containing precipitate. S7. The filtrate b obtained in S6 is evaporated at a temperature of 90℃ for 2 hours to remove water and obtain the regenerated eutectic solvent. S8. The regenerated eutectic solvent obtained in S7 is recycled to the operation of steps S4 to S7 2 to 3 times to obtain filtrate c. The pH value is adjusted to 11 with a sodium hydroxide aqueous solution with a concentration of 0.1 mol / L to 2 mol / L. The solution is heated and stirred at 95°C for 2 hours, filtered, and the filter residue is dried to obtain lithium phosphate product.

[0007] Preferably, the pretreatment method of the lithium cobalt oxide cathode sheet in S1 is as follows: the lithium cobalt oxide cathode sheet is leached with an aqueous sodium hydroxide solution with a concentration of 0.1 mol / L to 2 mol / L to remove the aluminum foil, and then filtered, washed with water and dried to obtain lithium cobalt oxide cathode powder; The pretreatment method for the lithium iron phosphate cathode sheet is as follows: the lithium iron phosphate cathode sheet is leached with an aqueous sodium hydroxide solution of 0.1 mol / L to 2 mol / L to extract the aluminum foil, and then filtered, washed with water and dried to obtain lithium iron phosphate cathode powder.

[0008] Preferably, the molar ratio of lithium cobalt oxide cathode powder to lithium iron phosphate cathode powder in the mixed cathode powder in S2 is (0.2~5):1.

[0009] Preferably, the molar ratio of the hydrogen bond donor and the hydrogen bond acceptor in S3 is (0.1-10):1.

[0010] Preferably, the hydrogen bond donor in S3 is one or two of lactic acid, oxalic acid dihydrate, urea, ethylene glycol, water, citric acid, tartaric acid, and acetic acid.

[0011] Preferably, the hydrogen bond acceptor in S3 is one or two of betaine, choline, choline chloride, guanidine hydrochloride, acetylcholine, and betaine hydrochloride.

[0012] Preferably, the mass ratio of the mixed positive electrode powder and the eutectic solvent in S4 is 0.5 g: (10-100) g.

[0013] Preferably, the coordination modifier in S5 is water, ethanol, methyl sulfoxide, or acetone; the mass of the coordination modifier in S5 is 1% to 50% of the mass of the leaching solution.

[0014] Preferably, the conditions for the light reduction process in S6 are: the light source is a mercury lamp, xenon lamp, LED lamp, or sunlight; when the light source is a mercury lamp, xenon lamp, or LED lamp, the light intensity is 10 mW / cm². 2 ~ 100mW / cm 2 .

[0015] Compared with the prior art, the present invention has the following advantages: 1. The process of this invention is simple and can achieve the purpose of synergistic enhanced leaching and selective separation of waste lithium cobalt oxide materials and waste lithium iron phosphate materials. It has the advantages of low cost, high recovery rate, and broad prospects for industrial application.

[0016] 2. The Co in the waste lithium cobalt oxide cathode of this invention 3+ It exhibits strong oxidizing properties, with a standard electrode potential (E°) of 1.82 V, significantly higher than that of Fe in lithium iron phosphate. 2+ At a given potential, lithium cobalt oxide cathode materials have the potential to act as oxidants. Leaching with a eutectic solvent can expose the Co content in lithium cobalt oxide cathode materials. 3+ This process oxidizes the lithium iron phosphate cathode material, thereby enhancing the leaching process. Introducing high-value waste lithium cobalt oxide cathode material into the leaching process not only achieves synergistic oxidation leaching and improves leaching efficiency, but also increases the economic value of the recycled materials. This addresses the problem of high cost and low efficiency in recycling single lithium iron phosphate, aligning with the recycling concept of "treating waste with waste."

[0017] 3. After disassembling and dismantling waste lithium iron phosphate batteries and waste lithium cobalt oxide batteries, positive electrode sheets are obtained. After pretreatment, lithium iron phosphate and lithium cobalt oxide positive electrode powders are obtained. The lithium iron phosphate positive electrode powder is leached using a eutectic solvent, while the added lithium cobalt oxide positive electrode powder acts as an oxidant to enhance the leaching process. The completely leached solution undergoes coordination separation and photoreduction separation to achieve selective recovery of cobalt, iron, phosphorus, and lithium. This method fully utilizes the inherent redox capabilities of the materials to enhance the leaching process, achieving efficient recovery of valuable elements from waste positive electrode materials and avoiding the need for additional oxidants and reductants. The recovery rate of cobalt, iron, phosphorus, and lithium is over 98.9%. The entire leaching process uses an environmentally friendly eutectic solvent, involving only water consumption and light usage, without generating acidic wastewater. Furthermore, the eutectic solvent can be recycled multiple times, greatly reducing environmental pollution and damage during the recycling of waste positive electrode materials and reducing recycling costs. This invention uses lithium cobalt oxide cathode material as an oxidant to achieve enhanced leaching of lithium iron phosphate cathode material and further achieves the goal of efficient recovery of valuable elements. The entire process has the advantages of low cost, high recovery rate, and broad prospects for industrial application.

[0018] The present invention will be further described in detail below with reference to the embodiments. Detailed Implementation

[0019] Example 1 This embodiment describes a method for enhancing the recycling of waste lithium iron phosphate materials using waste lithium cobalt oxide as an oxidant. The method is as follows: S1. After discharging the waste lithium cobalt oxide batteries, disassemble them using physical methods to obtain lithium cobalt oxide positive electrode sheets. After pretreatment, lithium cobalt oxide positive electrode powder is obtained. Waste lithium iron phosphate batteries are discharged and disassembled using physical methods to obtain lithium iron phosphate positive electrode sheets. After pretreatment, lithium iron phosphate positive electrode powder is obtained. The pretreatment method for the lithium cobalt oxide cathode sheet is as follows: the lithium cobalt oxide cathode sheet is leached with an aluminum foil using a sodium hydroxide aqueous solution with a concentration of 1 mol / L, and then filtered, washed with water, and dried to obtain lithium cobalt oxide cathode powder. The pretreatment method for the lithium iron phosphate cathode sheet is as follows: the lithium iron phosphate cathode sheet is leached with an aluminum foil in a sodium hydroxide aqueous solution with a concentration of 1 mol / L, and then filtered, washed with water and dried to obtain lithium iron phosphate cathode powder. The mass fractions of the following elements in lithium cobalt oxide (LCO) cathode powder are: Li 3.85%, Co 63.64%; The mass fractions of the following elements in lithium iron phosphate (LFP) cathode powder are: Li 3.09%, Fe 34.56%, P 19.71%; S2. Mix the lithium cobalt oxide cathode powder and lithium iron phosphate cathode powder obtained in S1 evenly to obtain a mixed cathode powder; the molar ratio of lithium cobalt oxide cathode powder to lithium iron phosphate cathode powder in the mixed cathode powder is 2:1. S3. After mixing 0.07 mol of hydrogen bond donor (oxalic acid dihydrate) and 0.07 mol of hydrogen bond acceptor (choline chloride) evenly, the mixture is magnetically stirred for 5 min at a temperature of 50℃ and a speed of 800 r / min, and then naturally cooled to room temperature to obtain a eutectic solvent. S4. Add the mixed cathode powder obtained in S2 to the eutectic solvent obtained in S3, and stir the reaction at 70℃ for 20 min to obtain the leaching solution; the mass ratio of the mixed cathode powder to the eutectic solvent is 0.5g:20g; use ICP-OES to detect the content of valuable elements in the filtrate, and use infrared spectroscopy to perform phase analysis on the filter residue; S5. Add a coordination modifier (water) to the leaching solution obtained in S4, stir for 5 minutes, filter to obtain filtrate a, and dry the remaining filter residue to obtain a cobalt-containing precipitate; the mass of the coordination modifier is 10% of the mass of the leaching solution; this step achieves selective separation of cobalt ions; the content of valuable elements in the filtrate is detected by ICP-OES, and the phase analysis of the filter residue is performed by infrared spectroscopy; S6. The filtrate a obtained in S5 is subjected to photoreduction treatment for 20 minutes while stirring. After filtration, filtrate b is obtained. The remaining filter residue is dried to obtain an iron-containing precipitate. The photoreduction treatment conditions are: the light source is an LED lamp; the light intensity is 10mW / cm². 2 This step achieves selective separation of iron ions. S7. The filtrate b obtained in S6 is evaporated at a temperature of 90℃ for 2 hours to remove water and obtain the regenerated eutectic solvent. S8. The regenerated eutectic solvent obtained in S7 is recycled to the operation of steps S4 to S7 three times to obtain filtrate c. The pH value is adjusted to 11 with a sodium hydroxide aqueous solution with a concentration of 1 mol / L. The solution is heated and stirred at 95℃ for 2 hours, filtered, and the filter residue is dried to obtain lithium phosphate product, thus realizing the recovery of phosphorus and lithium.

[0020] After testing and calculation, the method of using waste lithium cobalt oxide as an oxidant to enhance the recycling of waste lithium iron phosphate materials in this embodiment has an iron leaching rate of 99.9% and recovery rates of cobalt, iron, lithium and phosphorus of 99.6%, 99.8%, 99.9% and 99.6%, respectively.

[0021] Example 2 This embodiment describes a method for enhancing the recycling of waste lithium iron phosphate materials using waste lithium cobalt oxide as an oxidant. The method is as follows: S1. After discharging the waste lithium cobalt oxide batteries, disassemble them using physical methods to obtain lithium cobalt oxide positive electrode sheets. After pretreatment, lithium cobalt oxide positive electrode powder is obtained. Waste lithium iron phosphate batteries are discharged and disassembled using physical methods to obtain lithium iron phosphate positive electrode sheets. After pretreatment, lithium iron phosphate positive electrode powder is obtained. The pretreatment method for the lithium cobalt oxide cathode sheet is as follows: the lithium cobalt oxide cathode sheet is leached with a sodium hydroxide aqueous solution of concentration 0.5 mol / L to remove aluminum foil, and then filtered, washed with water and dried to obtain lithium cobalt oxide cathode powder; The pretreatment method for the lithium iron phosphate cathode sheet is as follows: the lithium iron phosphate cathode sheet is leached with a sodium hydroxide aqueous solution of concentration 0.5 mol / L to remove aluminum foil, and then filtered, washed with water and dried to obtain lithium iron phosphate cathode powder; The mass fractions of the following elements in lithium cobalt oxide (LCO) cathode powder are: Li 3.85%, Co 63.64%; The mass fractions of the following elements in lithium iron phosphate (LFP) cathode powder are: Li 3.09%, Fe 34.56%, P 19.71%; S2. Mix the lithium cobalt oxide cathode powder and lithium iron phosphate cathode powder obtained in S1 evenly to obtain a mixed cathode powder; the molar ratio of lithium cobalt oxide cathode powder to lithium iron phosphate cathode powder in the mixed cathode powder is 0.2:1; S3. After mixing 0.172 mol of hydrogen bond donor (lactic acid) and 0.029 mol of hydrogen bond acceptor (betaine hydrochloride) evenly, the mixture is magnetically stirred for 30 min at a temperature of 80℃ and a speed of 800 r / min, and then naturally cooled to room temperature to obtain a eutectic solvent. S4. Add the mixed cathode powder obtained in S2 to the eutectic solvent obtained in S3, and stir the reaction at 90℃ for 20 min to obtain the leaching solution; the mass ratio of the mixed cathode powder to the eutectic solvent is 0.5g:30g; use ICP-OES to detect the content of valuable elements in the filtrate, and use infrared spectroscopy to perform phase analysis on the filter residue; S5. Add a coordination modifier (ethanol) to the leaching solution obtained in S4, stir for 5 min, filter to obtain filtrate a, and dry the remaining filter residue to obtain a cobalt-containing precipitate; the mass of the coordination modifier is 20% of the mass of the leaching solution; this step achieves selective separation of cobalt ions; the content of valuable elements in the filtrate is detected by ICP-OES, and the phase analysis of the filter residue is performed by infrared spectroscopy; S6. The filtrate a obtained in S5 is subjected to photoreduction treatment for 30 minutes while stirring. After filtration, filtrate b is obtained. The remaining filter residue is dried to obtain an iron-containing precipitate. The photoreduction treatment conditions are: the light source is an LED lamp; the light intensity is 20mW / cm². 2 This step achieves selective separation of iron ions. S7. The filtrate b obtained in S6 is evaporated at a temperature of 90℃ for 2 hours to remove water and obtain the regenerated eutectic solvent. S8. The regenerated eutectic solvent obtained in S7 is recycled and the operation of steps S4 to S7 is repeated twice to obtain filtrate c. The pH value is adjusted to 11 with a sodium hydroxide aqueous solution with a concentration of 0.5 mol / L. The solution is heated and stirred at a temperature of 95℃ for 2 hours, filtered, and the filter residue is dried to obtain lithium phosphate product, thus realizing the recovery of phosphorus and lithium.

[0022] After testing and calculation, the method of using waste lithium cobalt oxide as an oxidant to enhance the recycling of waste lithium iron phosphate materials in this embodiment has an iron leaching rate of 99.7% and recovery rates of cobalt, iron, lithium and phosphorus of 99.5%, 99.7%, 99.8% and 99.6%, respectively.

[0023] Example 3 This embodiment describes a method for enhancing the recycling of waste lithium iron phosphate materials using waste lithium cobalt oxide as an oxidant. The method is as follows: S1. After discharging the waste lithium cobalt oxide batteries, disassemble them using physical methods to obtain lithium cobalt oxide positive electrode sheets. After pretreatment, lithium cobalt oxide positive electrode powder is obtained. Waste lithium iron phosphate batteries are discharged and disassembled using physical methods to obtain lithium iron phosphate positive electrode sheets. After pretreatment, lithium iron phosphate positive electrode powder is obtained. The pretreatment method for the lithium cobalt oxide cathode sheet is as follows: the lithium cobalt oxide cathode sheet is leached with a sodium hydroxide aqueous solution of concentration 0.1 mol / L to remove aluminum foil, and then filtered, washed with water and dried to obtain lithium cobalt oxide cathode powder; The pretreatment method for the lithium iron phosphate cathode sheet is as follows: the lithium iron phosphate cathode sheet is leached with a sodium hydroxide aqueous solution of 0.1 mol / L to remove the aluminum foil, and then filtered, washed with water and dried to obtain lithium iron phosphate cathode powder. The mass fractions of the following elements in lithium cobalt oxide (LCO) cathode powder are: Li 3.85%, Co 63.64%; The mass fractions of the following elements in lithium iron phosphate (LFP) cathode powder are: Li 3.09%, Fe 34.56%, P 19.71%; S2. Mix the lithium cobalt oxide cathode powder and lithium iron phosphate cathode powder obtained in S1 evenly to obtain a mixed cathode powder; the molar ratio of lithium cobalt oxide cathode powder to lithium iron phosphate cathode powder in the mixed cathode powder is 0.2:1; S3. After mixing 0.0647 mol of hydrogen bond donor (citric acid) and 0.0647 mol of hydrogen bond acceptor (betaine) evenly, the mixture is magnetically stirred for 60 min at a temperature of 100℃ and a speed of 1000 r / min, and then naturally cooled to room temperature to obtain a eutectic solvent. S4. Add the mixed cathode powder obtained in S2 to the eutectic solvent obtained in S3, and stir the reaction at 200℃ for 60 min to obtain the leaching solution; the mass ratio of the mixed cathode powder to the eutectic solvent is 0.5g:20g; use ICP-OES to detect the content of valuable elements in the filtrate, and use infrared spectroscopy to perform phase analysis on the filter residue; S5. Add a coordination modifier (methyl sulfoxide) to the leaching solution obtained in S4, stir for 10 min, filter to obtain filtrate a, and dry the remaining filter residue to obtain a cobalt-containing precipitate; the mass of the coordination modifier is 1% of the mass of the leaching solution; this step achieves selective separation of cobalt ions; the content of valuable elements in the filtrate is detected by ICP-OES, and the phase analysis of the filter residue is performed by infrared spectroscopy; S6. The filtrate a obtained in S5 is subjected to photoreduction treatment for 25 minutes while stirring. After filtration, filtrate b is obtained. The remaining filter residue is dried to obtain an iron-containing precipitate. The photoreduction treatment conditions are: the light source is a mercury lamp; the light intensity is 100 mW / cm². 2 This step achieves selective separation of iron ions. S7. The filtrate b obtained in S6 is evaporated at a temperature of 90℃ for 2 hours to remove water and obtain the regenerated eutectic solvent. S8. The regenerated eutectic solvent obtained in S7 is recycled and the operation of steps S4 to S7 is repeated twice to obtain filtrate c. The pH value is adjusted to 11 with a sodium hydroxide aqueous solution with a concentration of 0.1 mol / L. The solution is heated and stirred at 95°C for 2 hours, filtered, and the filter residue is dried to obtain lithium phosphate product, thus realizing the recovery of phosphorus and lithium.

[0024] After testing and calculation, the method of using waste lithium cobalt oxide as an oxidant to enhance the recycling of waste lithium iron phosphate materials in this embodiment has an iron leaching rate of 99.2% and recovery rates of cobalt, iron, lithium and phosphorus of 99.3%, 99.5%, 99.3% and 99.1%, respectively.

[0025] Example 4 This embodiment describes a method for enhancing the recycling of waste lithium iron phosphate materials using waste lithium cobalt oxide as an oxidant. The method is as follows: S1. After discharging the waste lithium cobalt oxide batteries, disassemble them using physical methods to obtain lithium cobalt oxide positive electrode sheets. After pretreatment, lithium cobalt oxide positive electrode powder is obtained. Waste lithium iron phosphate batteries are discharged and disassembled using physical methods to obtain lithium iron phosphate positive electrode sheets. After pretreatment, lithium iron phosphate positive electrode powder is obtained. The pretreatment method for the lithium cobalt oxide cathode sheet is as follows: the lithium cobalt oxide cathode sheet is leached with an aluminum foil in a sodium hydroxide aqueous solution with a concentration of 2 mol / L, and then filtered, washed with water and dried to obtain lithium cobalt oxide cathode powder. The pretreatment method for the lithium iron phosphate cathode sheet is as follows: the lithium iron phosphate cathode sheet is leached with an aluminum foil in a sodium hydroxide aqueous solution with a concentration of 2 mol / L, and then filtered, washed with water and dried to obtain lithium iron phosphate cathode powder. The mass fractions of the following elements in lithium cobalt oxide (LCO) cathode powder are: Li 3.85%, Co 63.64%; The mass fractions of the following elements in lithium iron phosphate (LFP) cathode powder are: Li 3.09%, Fe 34.56%, P 19.71%; S2. Mix the lithium cobalt oxide cathode powder and lithium iron phosphate cathode powder obtained in S1 evenly to obtain a mixed cathode powder; the molar ratio of lithium cobalt oxide cathode powder to lithium iron phosphate cathode powder in the mixed cathode powder is 5:1. S3. After mixing 0.426 mol of hydrogen bond donor (urea) and 0.0426 mol of hydrogen bond acceptor (choline) evenly, the mixture is magnetically stirred for 20 min at a temperature of 40℃ and a rotation speed of 900 r / min, and then naturally cooled to room temperature to obtain a eutectic solvent. S4. Add the mixed cathode powder obtained in S2 to the eutectic solvent obtained in S3, and stir the reaction at 25°C for 30 min to obtain the leaching solution; the mass ratio of the mixed cathode powder to the eutectic solvent is 0.5 g: 10 g; use ICP-OES to detect the content of valuable elements in the filtrate, and use infrared spectroscopy to perform phase analysis on the filter residue; S5. Add a coordination modifier (acetone) to the leaching solution obtained in S4, stir for 8 minutes, filter to obtain filtrate a, dry the remaining filter residue to obtain a cobalt-containing precipitate; the mass of the coordination modifier is 50% of the mass of the leaching solution; this step achieves selective separation of cobalt ions; the content of valuable elements in the filtrate is detected by ICP-OES, and the phase analysis of the filter residue is performed by infrared spectroscopy; S6. The filtrate a obtained in S5 is subjected to photoreduction treatment for 25 minutes while stirring. After filtration, filtrate b is obtained. The remaining filter residue is dried to obtain an iron-containing precipitate. The photoreduction treatment conditions are: the light source is a xenon lamp; the light intensity is 30 mW / cm². 2 This step achieves selective separation of iron ions. S7. The filtrate b obtained in S6 is evaporated at a temperature of 90℃ for 2 hours to remove water and obtain the regenerated eutectic solvent. S8. The regenerated eutectic solvent obtained in S7 is recycled and the operation of steps S4 to S7 is repeated 3 times to obtain filtrate c. The pH value is adjusted to 11 with a sodium hydroxide aqueous solution with a concentration of 2 mol / L. The solution is heated and stirred at 95℃ for 2 hours, filtered, and the filter residue is dried to obtain lithium phosphate product, thus realizing the recovery of phosphorus and lithium.

[0026] After testing and calculation, the method of using waste lithium cobalt oxide as an oxidant to enhance the recycling of waste lithium iron phosphate materials in this embodiment has an iron leaching rate of 99.2% and recovery rates of cobalt, iron, lithium and phosphorus of 99.3%, 99.4%, 99.6% and 99.4%, respectively.

[0027] Example 5 This embodiment describes a method for enhancing the recycling of waste lithium iron phosphate materials using waste lithium cobalt oxide as an oxidant. The method is as follows: S1. After discharging the waste lithium cobalt oxide batteries, disassemble them using physical methods to obtain lithium cobalt oxide positive electrode sheets. After pretreatment, lithium cobalt oxide positive electrode powder is obtained. Waste lithium iron phosphate batteries are discharged and disassembled using physical methods to obtain lithium iron phosphate positive electrode sheets. After pretreatment, lithium iron phosphate positive electrode powder is obtained. The pretreatment method for the lithium cobalt oxide cathode sheet is as follows: the lithium cobalt oxide cathode sheet is leached with an aluminum foil in a sodium hydroxide aqueous solution with a concentration of 1.5 mol / L, and then filtered, washed with water and dried to obtain lithium cobalt oxide cathode powder. The pretreatment method for the lithium iron phosphate cathode sheet is as follows: the lithium iron phosphate cathode sheet is leached with a sodium hydroxide aqueous solution of 1.5 mol / L to remove aluminum foil, and then filtered, washed with water and dried to obtain lithium iron phosphate cathode powder. The mass fractions of the following elements in lithium cobalt oxide (LCO) cathode powder are: Li 3.85%, Co 63.64%; The mass fractions of the following elements in lithium iron phosphate (LFP) cathode powder are: Li 3.09%, Fe 34.56%, P 19.71%; S2. Mix the lithium cobalt oxide cathode powder and lithium iron phosphate cathode powder obtained in S1 evenly to obtain a mixed cathode powder; the molar ratio of lithium cobalt oxide cathode powder to lithium iron phosphate cathode powder in the mixed cathode powder is 3:1. S3. After mixing 0.368 mol of hydrogen bond donor (ethylene glycol) and 0.0613 mol of hydrogen bond acceptor (guanidine hydrochloride) evenly, the mixture is magnetically stirred for 10 min at a temperature of 60℃ and a rotation speed of 800 r / min, and then naturally cooled to room temperature to obtain a eutectic solvent. S4. Add the mixed cathode powder obtained in S2 to the eutectic solvent obtained in S3, and stir the reaction at 60°C for 30 min to obtain the leaching solution; the mass ratio of the mixed cathode powder to the eutectic solvent is 0.5 g: 100 g; use ICP-OES to detect the content of valuable elements in the filtrate, and use infrared spectroscopy to perform phase analysis on the filter residue; S5. Add a coordination modifier (water) to the leaching solution obtained in S4, stir for 5 minutes, filter to obtain filtrate a, and dry the remaining filter residue to obtain a cobalt-containing precipitate; the mass of the coordination modifier is 15% of the mass of the leaching solution; this step achieves selective separation of cobalt ions; the content of valuable elements in the filtrate is detected by ICP-OES, and the phase analysis of the filter residue is performed by infrared spectroscopy; S6. The filtrate a obtained in S5 is subjected to photoreduction treatment for 27 minutes while stirring. After filtration, filtrate b is obtained. The remaining filter residue is dried to obtain an iron-containing precipitate. The photoreduction treatment is performed under the condition that the light source is sunlight. This step achieves selective separation of iron ions. S7. The filtrate b obtained in S6 is evaporated at a temperature of 90℃ for 2 hours to remove water and obtain the regenerated eutectic solvent. S8. The regenerated eutectic solvent obtained in S7 is recycled and the operation of steps S4 to S7 is repeated twice to obtain filtrate c. The pH value is adjusted to 11 with a sodium hydroxide aqueous solution with a concentration of 1.5 mol / L. The solution is heated and stirred at 95℃ for 2 hours, filtered, and the filter residue is dried to obtain lithium phosphate product, thus realizing the recovery of phosphorus and lithium.

[0028] After testing and calculation, the method of using waste lithium cobalt oxide as an oxidant to enhance the recycling of waste lithium iron phosphate materials in this embodiment has an iron leaching rate of 99.3% and recovery rates of cobalt, iron, lithium and phosphorus of 98.9%, 99.5%, 99.5% and 99.5% respectively.

[0029] Example 6 This embodiment describes a method for enhancing the recycling of waste lithium iron phosphate materials using waste lithium cobalt oxide as an oxidant. The method is as follows: S1. After discharging the waste lithium cobalt oxide batteries, disassemble them using physical methods to obtain lithium cobalt oxide positive electrode sheets. After pretreatment, lithium cobalt oxide positive electrode powder is obtained. Waste lithium iron phosphate batteries are discharged and disassembled using physical methods to obtain lithium iron phosphate positive electrode sheets. After pretreatment, lithium iron phosphate positive electrode powder is obtained. The pretreatment method for the lithium cobalt oxide cathode sheet is as follows: the lithium cobalt oxide cathode sheet is leached with an aluminum foil using a sodium hydroxide aqueous solution with a concentration of 1 mol / L, and then filtered, washed with water, and dried to obtain lithium cobalt oxide cathode powder. The pretreatment method for the lithium iron phosphate cathode sheet is as follows: the lithium iron phosphate cathode sheet is leached with an aluminum foil in a sodium hydroxide aqueous solution with a concentration of 1 mol / L, and then filtered, washed with water and dried to obtain lithium iron phosphate cathode powder. The mass fractions of the following elements in lithium cobalt oxide (LCO) cathode powder are: Li 3.85%, Co 63.64%; The mass fractions of the following elements in lithium iron phosphate (LFP) cathode powder are: Li 3.09%, Fe 34.56%, P 19.71%; S2. Mix the lithium cobalt oxide cathode powder and lithium iron phosphate cathode powder obtained in S1 evenly to obtain a mixed cathode powder; the molar ratio of lithium cobalt oxide cathode powder to lithium iron phosphate cathode powder in the mixed cathode powder is 0.5:1; S3. Mix 1.23 mol of hydrogen bond donor (water) and 0.123 mol of hydrogen bond acceptor (acetylcholine) evenly, and then magnetically stir for 30 min at 80℃ and 800 r / min. Allow to cool naturally to room temperature to obtain a eutectic solvent. S4. Add the mixed cathode powder obtained in S2 to the eutectic solvent obtained in S3, and stir the reaction at 100℃ for 40 min to obtain the leaching solution; the mass ratio of the mixed cathode powder to the eutectic solvent is 0.5g:25g; use ICP-OES to detect the content of valuable elements in the filtrate, and use infrared spectroscopy to perform phase analysis on the filter residue; S5. Add a coordination modifier (ethanol) to the leaching solution obtained in S4, stir for 5 minutes, filter to obtain filtrate a, and dry the remaining filter residue to obtain a cobalt-containing precipitate; the mass of the coordination modifier is 30% of the mass of the leaching solution; this step achieves selective separation of cobalt ions; the content of valuable elements in the filtrate is detected by ICP-OES, and the phase analysis of the filter residue is performed by infrared spectroscopy. S6. The filtrate a obtained in S5 is subjected to photoreduction treatment for 20 minutes while stirring. After filtration, filtrate b is obtained. The remaining filter residue is dried to obtain an iron-containing precipitate. The photoreduction treatment conditions are: the light source is an LED lamp or sunlight; the light intensity is 30 mW / cm².2 This step achieves selective separation of iron ions. S7. The filtrate b obtained in S6 is evaporated at a temperature of 90℃ for 2 hours to remove water and obtain the regenerated eutectic solvent. S8. The regenerated eutectic solvent obtained in S7 is recycled and the operation of steps S4 to S7 is repeated twice to obtain filtrate c. The pH value is adjusted to 11 with a sodium hydroxide aqueous solution with a concentration of 1 mol / L. The solution is heated and stirred at 95℃ for 2 hours, filtered, and the filter residue is dried to obtain lithium phosphate product, thus realizing the recovery of phosphorus and lithium.

[0030] After testing and calculation, the method of using waste lithium cobalt oxide as an oxidant to enhance the recycling of waste lithium iron phosphate materials in this embodiment has an iron leaching rate of 99.4%, and recovery rates of cobalt, iron, lithium and phosphorus are 99.4%, 99.4%, 99.6% and 99.2%, respectively.

[0031] Example 7 This embodiment describes a method for enhancing the recycling of waste lithium iron phosphate materials using waste lithium cobalt oxide as an oxidant. The method is as follows: S1. After discharging the waste lithium cobalt oxide batteries, disassemble them using physical methods to obtain lithium cobalt oxide positive electrode sheets. After pretreatment, lithium cobalt oxide positive electrode powder is obtained. Waste lithium iron phosphate batteries are discharged and disassembled using physical methods to obtain lithium iron phosphate positive electrode sheets. After pretreatment, lithium iron phosphate positive electrode powder is obtained. The pretreatment method for the lithium cobalt oxide cathode sheet is as follows: the lithium cobalt oxide cathode sheet is leached with an aluminum foil in a sodium hydroxide aqueous solution with a concentration of 1.2 mol / L, and then filtered, washed with water and dried to obtain lithium cobalt oxide cathode powder; The pretreatment method for the lithium iron phosphate cathode sheet is as follows: the lithium iron phosphate cathode sheet is leached with a sodium hydroxide aqueous solution of 1.2 mol / L to remove aluminum foil, and then filtered, washed with water and dried to obtain lithium iron phosphate cathode powder. The mass fractions of the following elements in lithium cobalt oxide (LCO) cathode powder are: Li 3.85%, Co 63.64%; The mass fractions of the following elements in lithium iron phosphate (LFP) cathode powder are: Li 3.09%, Fe 34.56%, P 19.71%; S2. Mix the lithium cobalt oxide cathode powder and lithium iron phosphate cathode powder obtained in S1 evenly to obtain a mixed cathode powder; the molar ratio of lithium cobalt oxide cathode powder to lithium iron phosphate cathode powder in the mixed cathode powder is 4:1. S3. After mixing 0.0605 mol of hydrogen bond donor (tartaric acid) with hydrogen bond acceptor (0.0303 mol of acetylcholine and 0.0303 mol of betaine hydrochloride) evenly, the mixture is magnetically stirred for 10 min at 70℃ and 850 r / min, and then naturally cooled to room temperature to obtain a eutectic solvent. S4. Add the mixed cathode powder obtained in S2 to the eutectic solvent obtained in S3, and stir the reaction at 40°C for 30 min to obtain the leaching solution; the mass ratio of the mixed cathode powder to the eutectic solvent is 0.5 g: 25 g; use ICP-OES to detect the content of valuable elements in the filtrate, and use infrared spectroscopy to perform phase analysis on the filter residue; S5. Add a coordination modifier (methyl sulfoxide) to the leaching solution obtained in S4, stir for 5 min, filter to obtain filtrate a, and dry the remaining filter residue to obtain a cobalt-containing precipitate; the mass of the coordination modifier is 10% of the mass of the leaching solution; this step achieves selective separation of cobalt ions; the content of valuable elements in the filtrate is detected by ICP-OES, and the phase analysis of the filter residue is performed by infrared spectroscopy; S6. The filtrate a obtained in S5 is subjected to photoreduction treatment for 20 minutes while stirring. After filtration, filtrate b is obtained. The remaining filter residue is dried to obtain an iron-containing precipitate. The photoreduction treatment conditions are: the light source is an LED lamp; the light intensity is 10mW / cm². 2 This step achieves selective separation of iron ions. S7. The filtrate b obtained in S6 is evaporated at a temperature of 90℃ for 2 hours to remove water and obtain the regenerated eutectic solvent. S8. The regenerated eutectic solvent obtained in S7 is recycled and the operations of S4 to S7 are repeated twice to obtain filtrate c. The pH value is adjusted to 11 with a sodium hydroxide aqueous solution with a concentration of 1.2 mol / L. The solution is heated and stirred at 95°C for 2 hours, filtered, and the filter residue is dried to obtain lithium phosphate product, thus realizing the recovery of phosphorus and lithium.

[0032] After testing and calculation, the method of using waste lithium cobalt oxide as an oxidant to enhance the recycling of waste lithium iron phosphate materials in this embodiment has an iron leaching rate of 99.6% and recovery rates of cobalt, iron, lithium and phosphorus of 99.4%, 99.3%, 99.6% and 99.4%, respectively.

[0033] Example 8 This embodiment describes a method for enhancing the recycling of waste lithium iron phosphate materials using waste lithium cobalt oxide as an oxidant. The method is as follows: S1. After discharging the waste lithium cobalt oxide batteries, disassemble them using physical methods to obtain lithium cobalt oxide positive electrode sheets. After pretreatment, lithium cobalt oxide positive electrode powder is obtained. Waste lithium iron phosphate batteries are discharged and disassembled using physical methods to obtain lithium iron phosphate positive electrode sheets. After pretreatment, lithium iron phosphate positive electrode powder is obtained. The pretreatment method for the lithium cobalt oxide cathode sheet is as follows: the lithium cobalt oxide cathode sheet is leached with an aluminum foil in a sodium hydroxide aqueous solution with a concentration of 2 mol / L, and then filtered, washed with water and dried to obtain lithium cobalt oxide cathode powder. The pretreatment method for the lithium iron phosphate cathode sheet is as follows: the lithium iron phosphate cathode sheet is leached with an aluminum foil in a sodium hydroxide aqueous solution with a concentration of 2 mol / L, and then filtered, washed with water and dried to obtain lithium iron phosphate cathode powder. The mass fractions of the following elements in lithium cobalt oxide (LCO) cathode powder are: Li 3.85%, Co 63.64%; The mass fractions of the following elements in lithium iron phosphate (LFP) cathode powder are: Li 3.09%, Fe 34.56%, P 19.71%; S2. Mix the lithium cobalt oxide cathode powder and lithium iron phosphate cathode powder obtained in S1 evenly to obtain a mixed cathode powder; the molar ratio of lithium cobalt oxide cathode powder to lithium iron phosphate cathode powder in the mixed cathode powder is 1:1; S3. After mixing 0.168 mol of hydrogen bond donor (acetic acid) with hydrogen bond acceptor (0.084 mol of choline chloride and 0.084 mol of guanidine hydrochloride) evenly, the mixture is magnetically stirred for 50 min at 80℃ and 800 r / min, and then naturally cooled to room temperature to obtain a eutectic solvent. S4. The mixed cathode powder obtained in S2 is added to the eutectic solvent obtained in S3, and the mixture is stirred and reacted at 200℃ for 30 min to obtain the leaching solution; the mass ratio of the mixed cathode powder to the eutectic solvent is 0.5g:25g; the content of valuable elements in the filtrate is detected by ICP-OES, and the phase composition of the filter residue is analyzed by infrared spectroscopy. S5. Add a coordination modifier (water) to the leaching solution obtained in S4, stir for 8 minutes, filter to obtain filtrate a, and dry the remaining filter residue to obtain a cobalt-containing precipitate; the mass of the coordination modifier is 25% of the mass of the leaching solution; this step achieves selective separation of cobalt ions; the content of valuable elements in the filtrate is detected by ICP-OES, and the phase analysis of the filter residue is performed by infrared spectroscopy; S6. The filtrate a obtained in S5 is subjected to photoreduction treatment for 30 minutes while stirring. After filtration, filtrate b is obtained. The remaining filter residue is dried to obtain an iron-containing precipitate. The photoreduction treatment conditions are: the light source is an LED lamp; the light intensity is 20mW / cm². 2 This step achieves selective separation of iron ions. S7. The filtrate b obtained in S6 is evaporated at a temperature of 90℃ for 2 hours to remove water and obtain the regenerated eutectic solvent. S8. The regenerated eutectic solvent obtained in S7 is recycled and the operation of steps S4 to S7 is repeated twice to obtain filtrate c. The pH value is adjusted to 11 with a sodium hydroxide aqueous solution with a concentration of 2 mol / L. The solution is heated and stirred at 95℃ for 2 hours, filtered, and the filter residue is dried to obtain lithium phosphate product, thus realizing the recovery of phosphorus and lithium.

[0034] After testing and calculation, the method of using waste lithium cobalt oxide as an oxidant to enhance the recycling of waste lithium iron phosphate materials in this embodiment has an iron leaching rate of 99.4%, and recovery rates of cobalt, iron, lithium and phosphorus are 99.4%, 99.7%, 99.8% and 99.3%, respectively.

[0035] Example 9 This embodiment describes a method for enhancing the recycling of waste lithium iron phosphate materials using waste lithium cobalt oxide as an oxidant. The method is as follows: S1. After discharging the waste lithium cobalt oxide batteries, disassemble them using physical methods to obtain lithium cobalt oxide positive electrode sheets. After pretreatment, lithium cobalt oxide positive electrode powder is obtained. Waste lithium iron phosphate batteries are discharged and disassembled using physical methods to obtain lithium iron phosphate positive electrode sheets. After pretreatment, lithium iron phosphate positive electrode powder is obtained. The pretreatment method for the lithium cobalt oxide cathode sheet is as follows: the lithium cobalt oxide cathode sheet is leached with an aluminum foil using a sodium hydroxide aqueous solution with a concentration of 1 mol / L, and then filtered, washed with water, and dried to obtain lithium cobalt oxide cathode powder. The pretreatment method for the lithium iron phosphate cathode sheet is as follows: the lithium iron phosphate cathode sheet is leached with an aluminum foil in a sodium hydroxide aqueous solution with a concentration of 1 mol / L, and then filtered, washed with water and dried to obtain lithium iron phosphate cathode powder. The mass fractions of the following elements in lithium cobalt oxide (LCO) cathode powder are: Li 3.85%, Co 63.64%; The mass fractions of the following elements in lithium iron phosphate (LFP) cathode powder are: Li 3.09%, Fe 34.56%, P 19.71%; S2. Mix the lithium cobalt oxide cathode powder and lithium iron phosphate cathode powder obtained in S1 evenly to obtain a mixed cathode powder; the molar ratio of lithium cobalt oxide cathode powder to lithium iron phosphate cathode powder in the mixed cathode powder is 2:1. S3. After mixing the hydrogen bond donor (0.093 mol lactic acid and 0.093 mol ethylene glycol) with the hydrogen bond acceptor (0.093 mol betaine and 0.093 mol choline) evenly, the mixture is magnetically stirred for 10 min at a temperature of 60℃ and a speed of 800 r / min, and then naturally cooled to room temperature to obtain a eutectic solvent. S4. The mixed cathode powder obtained in S2 is added to the eutectic solvent obtained in S3, and the mixture is stirred and reacted at 60°C for 20 min to obtain the leaching solution. The mass ratio of the mixed cathode powder to the eutectic solvent is 0.5 g: 25 g. The content of valuable elements in the filtrate is detected by ICP-OES, and the phase composition of the filter residue is analyzed by infrared spectroscopy. S5. Add a coordination modifier (water) to the leaching solution obtained in S4, stir for 5 minutes, filter to obtain filtrate a, and dry the remaining filter residue to obtain a cobalt-containing precipitate; the mass of the coordination modifier is 5% of the mass of the leaching solution; this step achieves selective separation of cobalt ions; the content of valuable elements in the filtrate is detected by ICP-OES, and the phase analysis of the filter residue is performed by infrared spectroscopy; S6. The filtrate a obtained in S5 is subjected to photoreduction treatment for 30 minutes while stirring. After filtration, filtrate b is obtained. The remaining filter residue is dried to obtain an iron-containing precipitate. The photoreduction treatment conditions are: the light source is an LED lamp; the light intensity is 40mW / cm². 2 This step achieves selective separation of iron ions. S7. The filtrate b obtained in S6 is evaporated at a temperature of 90℃ for 2 hours to remove water and obtain the regenerated eutectic solvent. S8. The regenerated eutectic solvent obtained in S7 is recycled to the operation of steps S4 to S7 three times to obtain filtrate c. The pH value is adjusted to 11 with a sodium hydroxide aqueous solution with a concentration of 1 mol / L. The solution is heated and stirred at 95℃ for 2 hours, filtered, and the filter residue is dried to obtain lithium phosphate product, thus realizing the recovery of phosphorus and lithium.

[0036] After testing and calculation, the method of using waste lithium cobalt oxide as an oxidant to enhance the recycling of waste lithium iron phosphate materials in this embodiment has an iron leaching rate of 99.3% and recovery rates of cobalt, iron, lithium and phosphorus of 99.4%, 99.3%, 99.8% and 99.9%, respectively.

[0037] Example 10 This embodiment describes a method for enhancing the recycling of waste lithium iron phosphate materials using waste lithium cobalt oxide as an oxidant. The method is as follows: S1. After discharging the waste lithium cobalt oxide batteries, disassemble them using physical methods to obtain lithium cobalt oxide positive electrode sheets. After pretreatment, lithium cobalt oxide positive electrode powder is obtained. Waste lithium iron phosphate batteries are discharged and disassembled using physical methods to obtain lithium iron phosphate positive electrode sheets. After pretreatment, lithium iron phosphate positive electrode powder is obtained. The pretreatment method for the lithium cobalt oxide cathode sheet is as follows: the lithium cobalt oxide cathode sheet is leached with an aluminum foil in a sodium hydroxide aqueous solution with a concentration of 2 mol / L, and then filtered, washed with water and dried to obtain lithium cobalt oxide cathode powder. The pretreatment method for the lithium iron phosphate cathode sheet is as follows: the lithium iron phosphate cathode sheet is leached with an aluminum foil in a sodium hydroxide aqueous solution with a concentration of 2 mol / L, and then filtered, washed with water and dried to obtain lithium iron phosphate cathode powder. The mass fractions of the following elements in lithium cobalt oxide (LCO) cathode powder are: Li 3.85%, Co 63.64%; The mass fractions of the following elements in lithium iron phosphate (LFP) cathode powder are: Li 3.09%, Fe 34.56%, P 19.71%; S2. Mix the lithium cobalt oxide cathode powder and lithium iron phosphate cathode powder obtained in S1 evenly to obtain a mixed cathode powder; the molar ratio of lithium cobalt oxide cathode powder to lithium iron phosphate cathode powder in the mixed cathode powder is 0.6:1; S3. After mixing the hydrogen bond donor (0.028 mol citric acid and 0.014 mol tartaric acid) with the hydrogen bond acceptor (0.028 mol betaine and 0.014 mol acetylcholine) evenly, the mixture is magnetically stirred for 15 min at 70℃ and 800 r / min, and then naturally cooled to room temperature to obtain a eutectic solvent. S4. Add the mixed cathode powder obtained in S2 to the eutectic solvent obtained in S3, and stir the reaction at 60℃ for 40 min to obtain the leaching solution; the mass ratio of the mixed cathode powder to the eutectic solvent is 0.5g:25g; use ICP-OES to detect the content of valuable elements in the filtrate, and use infrared spectroscopy to perform phase analysis on the filter residue; S5. Add a coordination modifier (ethanol) to the leaching solution obtained in S4, stir for 5 minutes, filter to obtain filtrate a, and dry the remaining filter residue to obtain a cobalt-containing precipitate; the mass of the coordination modifier is 20% of the mass of the leaching solution; this step achieves selective separation of cobalt ions; the content of valuable elements in the filtrate is detected by ICP-OES, and the phase analysis of the filter residue is performed by infrared spectroscopy. S6. The filtrate a obtained in S5 is subjected to photoreduction treatment for 20 minutes while stirring. After filtration, filtrate b is obtained. The remaining filter residue is dried to obtain an iron-containing precipitate. The photoreduction treatment conditions are: the light source is an LED lamp; the light intensity is 20mW / cm². 2 This step achieves selective separation of iron ions. S7. The filtrate b obtained in S6 is evaporated at a temperature of 90℃ for 2 hours to remove water and obtain the regenerated eutectic solvent. S8. The regenerated eutectic solvent obtained in S7 is recycled and the operation of steps S4 to S7 is repeated 3 times to obtain filtrate c. The pH value is adjusted to 11 with a sodium hydroxide aqueous solution with a concentration of 2 mol / L. The solution is heated and stirred at 95℃ for 2 hours, filtered, and the filter residue is dried to obtain lithium phosphate product, thus realizing the recovery of phosphorus and lithium.

[0038] After testing and calculation, the method of using waste lithium cobalt oxide as an oxidant to enhance the recycling of waste lithium iron phosphate materials in this embodiment has an iron leaching rate of 99.2% and recovery rates of cobalt, iron, lithium and phosphorus of 99.5%, 99.9%, 98.9% and 99.9% respectively.

[0039] Comparative Example 1 This comparative example illustrates a method for enhancing the recycling of waste lithium iron phosphate materials. The method is as follows: S1. Discharge and process the waste lithium iron phosphate batteries, disassemble them using physical methods to obtain lithium iron phosphate positive electrode sheets, and after pretreatment, obtain lithium iron phosphate positive electrode powder. The pretreatment method for the lithium iron phosphate cathode sheet is as follows: the lithium iron phosphate cathode sheet is leached with an aluminum foil in a sodium hydroxide aqueous solution with a concentration of 1 mol / L, and then filtered, washed with water and dried to obtain lithium iron phosphate cathode powder. The mass fractions of the following elements in lithium iron phosphate (LFP) cathode powder are: Li 3.09%, Fe 34.56%, P 19.71%; S2. After mixing 0.07 mol of hydrogen bond donor (oxalic acid dihydrate) and 0.07 mol of hydrogen bond acceptor (choline chloride) evenly, the mixture is magnetically stirred for 5 min at a temperature of 50℃ and a speed of 800 r / min, and then naturally cooled to room temperature to obtain a eutectic solvent. S3. The lithium iron phosphate cathode powder obtained in S1 is added to the eutectic solvent obtained in S2, and the mixture is stirred and reacted at a temperature of 70°C for 20 minutes to obtain the leached solution; the mass ratio of the lithium iron phosphate cathode powder to the eutectic solvent is 0.5g:20g.

[0040] After testing and calculation, the iron leaching rate was 29.9% when lithium iron phosphate cathode powder was leached alone without the addition of lithium cobalt oxide.

[0041] Comparative Example 2 The method for recycling waste lithium iron phosphate materials in this comparative example is as follows: S1. Discharge and process the waste lithium iron phosphate batteries, disassemble them using physical methods to obtain lithium iron phosphate positive electrode sheets, and after pretreatment, obtain lithium iron phosphate positive electrode powder. The pretreatment method for the lithium iron phosphate cathode sheet is as follows: the lithium iron phosphate cathode sheet is leached with a sodium hydroxide aqueous solution of concentration 0.5 mol / L to remove aluminum foil, and then filtered, washed with water and dried to obtain lithium iron phosphate cathode powder; The mass fractions of the following elements in lithium iron phosphate (LFP) cathode powder are: Li 3.09%, Fe 34.56%, P 19.71%; S2. After mixing 0.172 mol of hydrogen bond donor (lactic acid) and 0.029 mol of hydrogen bond acceptor (betaine hydrochloride) evenly, the mixture is magnetically stirred for 30 min at a temperature of 80℃ and a speed of 800 r / min, and then naturally cooled to room temperature to obtain a eutectic solvent. S3. The lithium iron phosphate cathode powder obtained in S2 is added to the eutectic solvent obtained in S3, and the mixture is stirred and reacted at a temperature of 90°C for 20 minutes to obtain the leached solution; the mass ratio of the lithium iron phosphate cathode powder to the eutectic solvent is 0.5g:15g.

[0042] S5. Add a coordination modifier (ethanol) to the leaching solution obtained in S4, stir for 5 min, filter to obtain filtrate a, and dry the remaining filter residue to obtain a cobalt-containing precipitate; the mass of the coordination modifier is 20% of the mass of the leaching solution; this step achieves selective separation of cobalt ions; the content of valuable elements in the filtrate is detected by ICP-OES, and the phase analysis of the filter residue is performed by infrared spectroscopy; S6. The filtrate a obtained in S5 is subjected to photoreduction treatment for 20 minutes while stirring. After filtration, filtrate b is obtained. The remaining filter residue is dried to obtain an iron-containing precipitate. The photoreduction treatment conditions are: the light source is an LED lamp; the light intensity is 20 mW / cm². 2 This step achieves selective separation of iron ions. S7. The filtrate b obtained in S6 is evaporated at a temperature of 90℃ for 2 hours to remove water and obtain the regenerated eutectic solvent. S8. The regenerated eutectic solvent obtained in S7 is recycled and the operation of steps S4 to S7 is repeated twice to obtain filtrate c. The pH value is adjusted to 11 with a sodium hydroxide aqueous solution with a concentration of 0.5 mol / L. The solution is heated and stirred at a temperature of 95℃ for 2 hours, filtered, and the filter residue is dried to obtain lithium phosphate product, thus realizing the recovery of phosphorus and lithium.

[0043] After testing and calculation, the iron leaching rate of lithium iron phosphate cathode powder without the addition of lithium cobalt oxide is 33.9%.

[0044] The method of using waste lithium cobalt oxide as an oxidant to enhance the recycling of waste lithium iron phosphate materials is simple and can achieve the purpose of synergistic enhanced leaching and selective separation of waste lithium cobalt oxide materials and waste lithium iron phosphate materials. It has the advantages of low cost, high recovery rate, and broad prospects for industrial application.

[0045] 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 enhancing the recycling of waste lithium iron phosphate materials using waste lithium cobalt oxide as an oxidant, characterized in that, The method is as follows: S1. After discharging the waste lithium cobalt oxide batteries, disassemble them using physical methods to obtain lithium cobalt oxide positive electrode sheets. After pretreatment, lithium cobalt oxide positive electrode powder is obtained. Waste lithium iron phosphate batteries are discharged and disassembled using physical methods to obtain lithium iron phosphate positive electrode sheets. After pretreatment, lithium iron phosphate positive electrode powder is obtained. S2. Mix the lithium cobalt oxide cathode powder and lithium iron phosphate cathode powder obtained in S1 evenly to obtain a mixed cathode powder. S3. After the hydrogen bond donor and hydrogen bond acceptor are mixed evenly, the mixture is magnetically stirred for 5 min to 60 min at a temperature of 50℃~100℃ and a rotation speed of 800 r / min~1000 r / min, and then naturally cooled to room temperature to obtain a eutectic solvent. S4. Add the mixed positive electrode powder obtained in S2 to the eutectic solvent obtained in S3, and stir the reaction at a temperature of 25℃~200℃ for 20min~60min to obtain the leaching solution. S5. Add a coordination modifier to the leaching solution obtained in S4, stir for 5 min to 10 min, filter to obtain filtrate a, and dry the remaining filter residue to obtain a cobalt-containing precipitate. S6. The filtrate a obtained in S5 is subjected to photoreduction treatment for 20 min to 30 min while stirring. After filtration, filtrate b is obtained. The remaining filter residue is dried to obtain an iron-containing precipitate. S7. The filtrate b obtained in S6 is evaporated at a temperature of 90℃ for 2 hours to remove water and obtain the regenerated eutectic solvent. S8. The regenerated eutectic solvent obtained in S7 is recycled to the operation of steps S4 to S7 2 to 3 times to obtain filtrate c. The pH value is adjusted to 11 with a sodium hydroxide aqueous solution with a concentration of 0.1 mol / L to 2 mol / L. The solution is heated and stirred at 95°C for 2 hours, filtered, and the filter residue is dried to obtain lithium phosphate product.

2. The method for enhancing the recycling of waste lithium iron phosphate materials using waste lithium cobalt oxide as an oxidant according to claim 1, characterized in that, The pretreatment method for the lithium cobalt oxide cathode sheet described in S1 is as follows: the lithium cobalt oxide cathode sheet is leached with an aqueous sodium hydroxide solution of 0.1 mol / L to 2 mol / L to remove the aluminum foil, and then filtered, washed with water and dried to obtain lithium cobalt oxide cathode powder; The pretreatment method for the lithium iron phosphate cathode sheet is as follows: the lithium iron phosphate cathode sheet is leached with an aqueous sodium hydroxide solution of 0.1 mol / L to 2 mol / L to extract the aluminum foil, and then filtered, washed with water and dried to obtain lithium iron phosphate cathode powder.

3. The method for enhancing the recycling of waste lithium iron phosphate materials using waste lithium cobalt oxide as an oxidant according to claim 1, characterized in that, The molar ratio of lithium cobalt oxide cathode powder to lithium iron phosphate cathode powder in the mixed cathode powder described in S2 is (0.2~5):

1.

4. The method for enhancing the recycling of waste lithium iron phosphate materials using waste lithium cobalt oxide as an oxidant according to claim 1, characterized in that, The molar ratio of hydrogen bond donor to hydrogen bond acceptor in S3 is (0.1-10):

1.

5. The method for enhancing the recycling of waste lithium iron phosphate materials using waste lithium cobalt oxide as an oxidant according to claim 1, characterized in that, The hydrogen bond donors mentioned in S3 are one or two of the following: lactic acid, oxalic acid dihydrate, urea, ethylene glycol, water, citric acid, tartaric acid, and acetic acid.

6. The method for enhancing the recycling of waste lithium iron phosphate materials using waste lithium cobalt oxide as an oxidant according to claim 1, characterized in that, The hydrogen bond acceptor described in S3 is one or two of betaine, choline, choline chloride, guanidine hydrochloride, acetylcholine, and betaine hydrochloride.

7. The method for enhancing the recycling of waste lithium iron phosphate materials using waste lithium cobalt oxide as an oxidant according to claim 1, characterized in that, The mass ratio of the mixed positive electrode powder and the eutectic solvent in S4 is 0.5 g: (10-100) g.

8. The method for enhancing the recycling of waste lithium iron phosphate materials using waste lithium cobalt oxide as an oxidant according to claim 1, characterized in that, The coordination modifier mentioned in S5 is water, ethanol, methyl sulfoxide, or acetone; the mass of the coordination modifier mentioned in S5 is 1% to 50% of the mass of the leaching solution.

9. A method for enhancing the recycling of waste lithium iron phosphate materials using waste lithium cobalt oxide as an oxidant according to claim 1, characterized in that, The conditions for the light reduction process described in S6 are: the light source is a mercury lamp, xenon lamp, LED lamp, or sunlight; when the light source is a mercury lamp, xenon lamp, or LED lamp, the light intensity is 10 mW / cm². 2 ~ 100mW / cm 2 .