Method for recycling ternary lithium battery material from water-ionic liquid two-phase system

Abstract

The invention relates to a method for recycling a ternary lithium battery material by a water-ionic liquid two-phase system, and mainly solves the problems of low leaching efficiency and high cost in the prior art. The recycling method comprises the following steps: adding the waste ternary lithium battery electrode material into a lithium battery recycling solvent for leaching reaction, and after the reaction is finished, realizing solid-liquid separation through vacuum filtration to obtain a leaching solution rich in valuable metal ions such as Li, Ni, Co and Mn; slowly dropwise adding the leachate into acetone to carry out a back extraction process, separating a metal ion aqueous solution from the ionic liquid, and carrying out Ni, Co and Mn ion concentration regulation on the metal ion solution; separating the mixed solution through a rotary evaporator to respectively obtain acetone and a metal ion aqueous solution; according to the technical scheme, the problems are well solved, and the method can be used for industrial application of recycling the positive electrode of the waste ternary lithium battery.

Description

Technical Field

[0001] The invention belongs to the technical field of waste battery recycling, and in particular relates to a method for recycling ternary lithium battery materials using a water-ionic liquid two-phase system. Background Art

[0002] With the rapid development of the electric vehicle market, the demand for lithium batteries is increasing, and a large number of waste lithium batteries are also generated. These waste lithium batteries contain a large amount of valuable metals, such as lithium, nickel, cobalt, manganese, etc. If they are discarded at will, it will not only cause waste of resources, but also pollute the environment. Therefore, how to effectively recycle the valuable metals in these waste lithium batteries has become an important research direction in the field of battery recycling. Among them, ionic liquid leaching technology is a new type of hydrometallurgical technology with the advantages of low toxicity, low volatility, and strong designability. It is widely used in the leaching and recovery of various metals.

[0003] The existing recycling technology of waste lithium battery positive electrode materials is mainly carried out through pyrometallurgy, hydrometallurgy and bioleaching. Pyrometallurgy is to convert the valuable metals in the waste batteries into alloys by high-temperature smelting, and then further extract the valuable metals by electrolysis and other methods. Hydrometallurgy is to dissolve the valuable metals in the waste batteries into the solution through chemical leaching agents, and then separate and purify the valuable metals through precipitation, solvent extraction, ion exchange and other methods. Bioleaching uses the biological activity of microorganisms to dissolve the valuable metals in the waste batteries into the solution.

[0004] However, there are some problems with the existing recycling technology of waste lithium battery positive electrode materials. First, pyrometallurgy has high energy consumption and produces a large amount of harmful gases, which has a great impact on the environment. Secondly, the chemical leaching agents in hydrometallurgy are often highly corrosive, the operating conditions are harsh, and secondary pollution is easy to occur. In addition, the efficiency of bioleaching is low, and it is currently difficult to achieve large-scale industrial application. Therefore, the development of an efficient, environmentally friendly and safe method for recycling waste lithium battery positive electrode materials is an important topic in the current battery recycling field.

[0005] Chinese patent CN116835663A proposes a method for recycling cobalt oxide lithium battery materials by mixing functional group modified ionic liquid with polyol, which mainly uses ionic liquid and polyol as leaching solution, and has high extraction efficiency only for Li and Co ions, but does not extract Ni and Mn in ternary lithium batteries, while its efficiency for extracting ternary lithium batteries is 90% to 92%. This method does not mention the recycling of ionic liquids, and the main raw materials of this method are polyols, which increases the production cost. The present invention uses ionic liquid and deionized water as leaching solution, and recovers ternary lithium batteries. In this field, it is necessary to overcome technical difficulties while ensuring high leaching effect, wherein water is used to replace polyols and ionic liquids are recycled and reused, and the cost is reduced by controlling the amount of oxalic acid aqueous solution in the process. Summary of the invention

[0006] The technical problem to be solved by the present invention is that the existing technology has the problems of low leaching efficiency and high cost. A new method for recovering ternary lithium battery materials in a water-ionic liquid two-phase system is provided, which has the advantages of high leaching efficiency and low cost.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: a method for recovering ternary lithium battery materials in a water-ionic liquid two-phase system, characterized in that it comprises the following steps:

[0008] S1. Prepare a water-ionic liquid two-phase system as a lithium battery recovery leaching agent: react a mixture of 1-methylimidazole and 3-chloro-1,2-propylene glycol in a molar ratio of 1:1 under a N2 environment at a reaction temperature of 95-105°C and stir for 20-24 hours, wash the product three times with ethyl acetate to remove unreacted raw materials, separate the liquid to remove the detergent, and then vacuum dry the product at 85-95°C, and then mix it with a calculated amount of deionized water and stir it thoroughly to obtain a lithium battery recovery leaching agent;

[0009] S2, adding the waste ternary lithium battery positive electrode material to the lithium battery recovery leaching agent to carry out leaching reaction, and after the reaction is completed, vacuum filtration is used to separate the solid and liquid to obtain a leaching solution rich in Li, Ni, Co, and Mn metal ions;

[0010] S3, slowly dropping the leachate in S2 into acetone to carry out a stripping process, wherein the metal ions and water in the leachate are transferred into acetone to form a mixed solution, which is separated from the ionic liquid, and the ionic liquid is recycled by removing residual water and solvent to obtain an ionic liquid with a purity greater than 95%. Compared with other organic solvents, the use of deionized water in the two-phase leaching system facilitates the recovery of high-purity ionic liquids, and the recovery rate of the ionic liquid is greater than 90%;

[0011] S4, separating the mixed solution described in S3 by a rotary evaporator to obtain acetone and a metal ion aqueous solution respectively, realizing acetone recovery, and adjusting the concentrations of Ni, Co, and Mn ions in the metal ion solution by NiCl2·6H2O, CoCl2·6H2O, and MnCl2·4H2O to adapt to ternary lithium battery precursor materials with different nickel-cobalt-manganese ratios;

[0012] S5, adding an oxalic acid aqueous solution to the metal ion aqueous solution described in S4 to perform a coprecipitation reaction of Ni, Co, and Mn ions, and obtaining a lithium ion aqueous solution and a nickel-cobalt-manganese oxalate precipitate by solid-liquid separation;

[0013] S6, adding a saturated sodium carbonate solution to the lithium ion aqueous solution described in S5 to carry out a precipitation reaction to obtain a Li2CO3 precipitate;

[0014] S7, calcining the nickel-cobalt-manganese oxalate coprecipitate described in S5 to prepare nickel-cobalt-manganese oxide;

[0015] S8. Mix the Li2CO3 precipitate described in S6 and the nickel-cobalt-manganese oxide described in S7 and calcine them at high temperature to prepare a precursor of the positive electrode material for a ternary lithium battery.

[0016] In the above technical solution, preferably, in S1, in the water-ionic liquid two-phase system, the mass fraction of deionized water in the lithium battery recovery leaching agent is 4.8-16.7wt%.

[0017] In the above technical solution, preferably, in S2, the leaching reaction temperature is 125-135°C, the leaching time is 12-16h, and it is carried out under mechanical stirring at 300-400r / min.

[0018] In the above technical solution, preferably, in S2, the solid-to-liquid ratio of the waste ternary lithium battery positive electrode material to the lithium battery recovery solvent is 10 to 45 g / L.

[0019] In the above technical solution, preferably, in S3, the mass ratio of acetone to leaching solution in the stripping process is 1 to 1.5:1.

[0020] In the above technical scheme, preferably, in S4, the temperature of the rotary evaporation process is 30-40°C, the rotation speed is 60-70r / min, the molar ratio of Ni:Co:Mn in the prepared metal ion solution is 1:1:1, 5:2:3, 6:2:2 or 8:1:1, and the concentration of the oxalic acid aqueous solution is 0.4-0.5mol / L.

[0021] In the above technical solution, preferably, in S5, the coprecipitation reaction temperature is 65-75°C, the pH is 1.98±0.3, and the reaction time is 4-6h.

[0022] In the above technical solution, preferably, in S6, the reaction temperature is 60-75° C., and the reaction time is 4-6 h.

[0023] In the above technical solution, preferably, in S7, the nickel cobalt manganese oxalate precipitation calcination temperature is 650-750°C, the time is 9-11 hours, and the molar ratio of Ni:Co:Mn in the nickel cobalt manganese oxide is one of 1:1:1, 5:2:3, 6:2:2 or 8:1:1.

[0024] In the above technical solution, preferably, in S8, the mixture is calcined at a temperature of 850 to 950° C. for 9 to 11 hours.

[0025] The anions and cations in the ionic liquid of the present invention can damage the black powder material of the lithium battery, causing it to decompose, and further dissolve and adsorb the valuable metal ions therein. The reducing properties of the cations dissolve metal oxides, while the halogen anions can complex heavy metal elements. When the reduction and complexation process of the anions and cations reaches the upper limit, that is, the metal ion concentration in the entire leaching system is saturated and the solubility reaches the upper limit. In order to increase the solubility upper limit of the leaching system, deionized water is introduced and fully mixed with the ionic liquid to form a two-phase leaching system. The presence of deionized water promotes the transfer of metal ions dissolved in the ionic liquid phase into the water as a carrier for carrying metal ions. In addition, deionized water and ionic liquids are mutually soluble, and the introduction of water molecules expands the distance between anions and cations in the ionic liquid, thereby improving the fluidity and solubility of the ionic liquid. Finally, the dual-phase leaching system of the present invention has a leaching efficiency of more than 99.8% for the valuable metal ions Li, Ni, Co and Mn in the black powder material of the ternary lithium battery, and the leaching rate of impurity metal elements is less than 5%; the ionic liquid is recycled by removing residual water and solvent to obtain an ionic liquid with a purity greater than 95%. Compared with other organic solvents, the use of deionized water in the dual-phase leaching system facilitates the recovery of high-purity ionic liquids, and the ionic liquid recovery rate is greater than 90%. In addition, a variety of valuable metal ions (Li, Ni, Co, Mn) in ternary lithium battery materials other than lithium cobalt oxide can also be efficiently and selectively extracted. It is surprisingly found that when the pH value in the co-precipitation reaction of Ni, Co, and Mn ions is adjusted to 1.98±0.3, Ni, Co, and Mn precipitation is more complete, and the amount of oxalic acid aqueous solution can be reduced, reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0027] Figure 1 The overall framework diagram for recycling ternary lithium battery materials in a water-ionic liquid two-phase system;

[0028] Figure 2 This is a schematic diagram of the whole process of recycling ternary lithium battery materials in a water-ionic liquid two-phase system;

[0029] Figure 3 The schematic diagram and nuclear magnetic resonance C spectrum of lithium battery recovery solvent;

[0030] Figure 4 Infrared spectrum of solvent recovered for lithium batteries. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0032] Embodiment 1:

[0033] S1: Discharge, disassemble and remove impurities from waste ternary lithium batteries to prepare positive electrode materials; synthesize lithium battery recovery solvent: add 3-chloro-1,2-propanediol (1105g, 10mol) to 1-methylimidazole (821g, 10mol) dropwise, and react with mechanical stirring at 300r / min in a N2 atmosphere at 100°C for 24h. After the reaction, wash with ethyl acetate for 3 times, finally remove the detergent by vacuum, and fully mix with the calculated amount of deionized water to obtain a lithium battery recovery solvent.

[0034] S2: Take 25g of black powder and add it to a three-necked flask containing 1000mL of lithium battery recovery solvent. Leach the reaction at 130℃ and 300r / min mechanical stirring for 14h. After the reaction, vacuum filtration is used to separate the solid and liquid, and the leachate and filter residue are collected separately. ICP-OES (inductively coupled plasma emission spectrometer) is used to analyze and detect the metal ion concentration in the leachate, and the metal ion leaching efficiency is calculated. The leaching results show that the leaching efficiencies of Li, Ni, Co, and Mn are 99.97%, 99.90%, 99.95%, and 99.93%, respectively.

[0035] S3: Mix the leachate with an equal volume of acetone and perform a stripping process to enrich the metal ion aqueous solution. Slowly drop 1000mL of leachate into a three-necked flask containing 1000mL of acetone, and maintain a mechanical stirring speed of 300r / min throughout the stripping process. After the addition is completed, continue stirring for 2h, and then transfer the mixture in the flask to a separatory funnel; after standing for 1h to separate the layers, separate the upper acetone / metal ion aqueous solution mixture and the lower ionic liquid by separation. The lower ionic liquid contains a small amount of water and acetone, which are removed by vacuum heating to achieve ionic liquid regeneration;

[0036] S4: The upper acetone / metal ion aqueous solution mixture is passed through a rotary evaporator at 30°C and 60r / min to recover acetone, and the remaining enriched metal aqueous solution is transferred to a flask. The concentration of each valuable metal ion in the metal aqueous solution is obtained by ICP-OES detection, and the concentration of the three metal ions of nickel, cobalt and manganese are adjusted by NiCl2·6H2O, CoCl2·6H2O and MnCl2·4H2O to match the three-element ratio required for the ternary lithium battery (such as NCM111, NCM523, and high nickel systems NCM622 and NCM811). This example takes the high-nickel system NCM622 as an example. At this time, the concentrations of Ni, Co, and Mn ions in the enriched solution are 50.4, 24.2, and 21.8 mg / mL, respectively. In order to make the molar ratio of Ni:Co:Mn in the system be 6:2:2, calculated amounts of NiCl2·6H2O, CoCl2·6H2O, and MnCl2·4H2O are added, and the mixture is fully stirred for subsequent co-precipitation experiments.

[0037] S5: Take 50.4g of oxalic acid dihydrate (H2C2O4·2H2O) and dissolve it in 1000mL of deionized water to prepare a 0.4mol / L oxalic acid aqueous solution. Add oxalic acid solution to the aqueous solution after adjusting the metal ions to carry out nickel-cobalt-manganese ion coprecipitation reaction, the reaction temperature is 70°C, 300r / min, and the pH is maintained at 1.98, and the reaction time is 6h. The nickel-cobalt-manganese oxalate coprecipitation product and lithium-rich filtrate are obtained by vacuum filtration, and dried in a 100°C oven, and finally calcined in a 750°C muffle furnace for 9h to obtain nickel-cobalt-manganese oxide.

[0038] S6: Add saturated Na2CO3 solution to the lithium-rich filtrate and react at 70°C for 6 hours, during which bubbles are generated, which is caused by the generation of CO2 gas under acidic conditions. After 6 hours, the reaction ends and solid products are precipitated. Li2CO3 precipitate is obtained by vacuum filtration and separation; it is dried at 100°C, then mixed evenly with nickel-cobalt-manganese oxide and calcined at 950°C for 9 hours to obtain the positive electrode precursor material of the ternary lithium battery.

[0039] Embodiment 2~6:

[0040] The experimental steps of Examples 2 to 6 are consistent with those of Example 1, except that the reaction condition parameters and the solid-liquid ratio of the waste ternary lithium battery positive electrode powder to the lithium battery recovery solvent are different. Specific experimental data are shown in Table 1.

[0041] Comparative Example 1:

[0042] The implementation steps of Comparative Example 1 were experimented with reference to the embodiment of Chinese patent CN116835663A. The specific parameters and experimental data are shown in Table 1.

[0043] Comparative Example 2:

[0044] Experiments were conducted using waste ternary lithium battery positive electrode materials according to Chinese patent CN116835663A. The specific parameters and experimental data are shown in Table 1.

[0045] Table 1 Solid-liquid ratio and result data of Examples 1 to 6 and Comparative Examples 1 to 2

[0046]

[0047]

[0048] It can be seen from Table 1 that the leaching rate of ternary lithium battery materials recovered by the water-ionic liquid two-phase system of the present invention is better than the leaching rate of Comparative Examples 1 to 2, and the purity of the recycled ionic liquid is higher than 95%, and the recovery rate is higher than 90%, which reduces the cost expenditure. Example 5 is the result of applying the recycled ionic liquid to recover the ternary lithium battery materials, and the result is also better than the leaching rate of the comparative example; and it is surprisingly found that when the pH value in the Ni, Co, and Mn ion co-precipitation reaction is adjusted to 1.98±0.3, Ni, Co, and Mn are precipitated more completely, and the amount of oxalic acid aqueous solution can be reduced, thereby reducing production costs.

Claims

1. A method for recovering ternary lithium battery materials using a water-ionic liquid two-phase system, characterized in that: The following steps are involved: S1. Prepare a water-ionic liquid two-phase system as a lithium battery recovery leaching agent: react a mixture of 1-methylimidazole and 3-chloro-1,2-propylene glycol in a molar ratio of 1:1 under a N2 environment at a reaction temperature of 95-105°C and stir for 20-24 hours, wash the product three times with ethyl acetate to remove unreacted raw materials, separate the liquid to remove the detergent, and then vacuum dry the product at 85-95°C, and then mix it with a calculated amount of deionized water and stir it thoroughly to obtain a lithium battery recovery leaching agent; S2, adding the waste ternary lithium battery positive electrode material to the lithium battery recovery leaching agent to carry out leaching reaction, and after the reaction is completed, vacuum filtration is used to separate the solid and liquid to obtain a leaching solution rich in Li, Ni, Co, and Mn metal ions; S3, slowly dropping the leachate in S2 into acetone to carry out a stripping process, wherein the metal ions and water in the leachate are transferred into acetone to form a mixed solution, which is separated from the ionic liquid, and the ionic liquid is recycled by removing residual water and solvent to obtain an ionic liquid with a purity greater than 95%. Compared with other organic solvents, the use of deionized water in the two-phase leaching system facilitates the recovery of high-purity ionic liquids, and the recovery rate of the ionic liquid is greater than 90%; S4, separating the mixed solution described in S3 by a rotary evaporator to obtain acetone and a metal ion aqueous solution respectively, realizing acetone recovery, and adjusting the concentrations of Ni, Co, and Mn ions in the metal ion solution by NiCl2·6H2O, CoCl2·6H2O, and MnCl2·4H2O to adapt to ternary lithium battery precursor materials with different nickel-cobalt-manganese ratios; S5, adding an oxalic acid aqueous solution to the metal ion aqueous solution described in S4 to perform a coprecipitation reaction of Ni, Co, and Mn ions, and obtaining a lithium ion aqueous solution and a nickel-cobalt-manganese oxalate precipitate by solid-liquid separation; S6, adding a saturated sodium carbonate solution to the lithium ion aqueous solution described in S5 to carry out a precipitation reaction to obtain a Li2CO3 precipitate; S7, calcining the nickel-cobalt-manganese oxalate coprecipitate described in S5 to prepare nickel-cobalt-manganese oxide; S8. Mix the Li2CO3 precipitate described in S6 and the nickel-cobalt-manganese oxide described in S7 and calcine them at high temperature to prepare a precursor of the positive electrode material for a ternary lithium battery.

2. The method for recovering ternary lithium battery materials using a water-ionic liquid two-phase system according to claim 1, characterized in that: In S1, in the water-ionic liquid two-phase system, the mass fraction of deionized water in the lithium battery recovery leaching agent is 4.8-16.7 wt%.

3. The method for recovering ternary lithium battery materials using a water-ionic liquid two-phase system according to claim 1, characterized in that: In S2, the leaching reaction temperature is 125-135°C, the leaching time is 12-16 hours, and it is carried out under mechanical stirring at 300-400 r / min.

4. The method for recovering ternary lithium battery materials using a water-ionic liquid two-phase system according to claim 1, characterized in that: In S2, the solid-to-liquid ratio of the waste ternary lithium battery positive electrode material to the lithium battery recovery solvent is 10 to 45 g / L.

5. The method for recovering ternary lithium battery materials using a water-ionic liquid two-phase system according to claim 1, characterized in that: In S3, the mass ratio of acetone to leaching solution in the stripping process is 1 to 1.5:

1.

6. The method for recovering ternary lithium battery materials using a water-ionic liquid two-phase system according to claim 1, characterized in that: In S4, the temperature of the rotary evaporation process is 30-40°C, the rotation speed is 60-70r / min, the molar ratio of Ni:Co:Mn in the prepared metal ion solution is 1:1:1, 5:2:3, 6:2:2 or 8:1:1, and the concentration of the oxalic acid aqueous solution is 0.4-0.5mol / L.

7. The method for recovering ternary lithium battery materials using a water-ionic liquid two-phase system according to claim 1, characterized in that: In S5, the coprecipitation reaction temperature is 65-75°C, the pH is 1.98±0.3, and the reaction time is 4-6h.

8. The method for recovering ternary lithium battery materials using a water-ionic liquid two-phase system according to claim 1, characterized in that: In S6, the reaction temperature is 60-75° C., and the reaction time is 4-6 hours.

9. The method for recovering ternary lithium battery materials using a water-ionic liquid two-phase system according to claim 1, characterized in that: In S7, the nickel cobalt manganese oxalate precipitate is calcined at a temperature of 650-750°C for 9-11 hours, and the molar ratio of Ni:Co:Mn in the nickel cobalt manganese oxide is one of 1:1:1, 5:2:3, 6:2:2 or 8:1:

1.

10. The method for recovering ternary lithium battery materials using a water-ionic liquid two-phase system according to claim 1, characterized in that: In S8, the mixture is preferably calcined at a temperature of 850 to 950°C for a time of 9 to 11 hours.

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