Method for preparing catalyst by recycling metal in waste ternary lithium battery

Abstract

The invention discloses a method for preparing a catalyst by recycling metal in a waste ternary lithium battery, which comprises the following steps: after obtaining positive electrode powder, adding the positive electrode powder into a deep eutectic solvent, and leaching to obtain a leaching solution; adding a dimethylglyoxime solution into the leachate to remove nickel, calculating according to the measured element concentrations of Co and Mn, supplementing Co salt or Mn salt, or adding potassium salt or sodium salt into the mixed solution, uniformly stirring, adding an oxalic acid solution into the mixed solution, filtering, washing, and drying to obtain the nickel-cobalt-cobalt-cobalt-cobalt-cobalt-cobalt-cobalt-cobalt-cobalt-cobalt-cobalt-cobalt-cobalt-cobalt-cobalt-cobalt-cobalt-cobalt-cobalt-cobalt-cobalt-cobalt- and carrying out centrifugal separation, washing, drying and calcining on the obtained precipitate to obtain the CoMn2O4 spinel material or the potassium-doped CoMn2O4 spinel material or the sodium-doped CoMn2O4 spinel material. And the hydrotalcite-like compound can be directly prepared from the leachate. The leachate obtained by leaching the positive electrode material through the deep-eutectic solvent system can be directly used for synthesis of spinel type or hydrotalcite-like materials without complex post-treatment.

Description

Technical Field

[0001] The present invention relates to the field of waste battery recycling, and particularly to a method for recycling metals in waste ternary lithium batteries to prepare catalysts. Background Art

[0002] Ternary nickel cobalt manganese lithium batteries (referred to as NCM batteries) occupy a crucial position in the fields of new energy vehicles and energy storage due to their excellent energy density and electrochemical performance. The contents of lithium (Li), nickel (Ni), cobalt (Co), and manganese (Mn) elements in these batteries significantly exceed those in natural ores. Therefore, retired ternary lithium-ion batteries have become an important secondary resource treasure rich in these key metals, with great recycling value. Thus, the recycling and circular reuse of NCM batteries are particularly urgent and important. Solving the problem of how to efficiently recycle heavy metal elements in waste ternary lithium batteries is an urgent technical problem.

[0003] Deep Eutectic Solvents (DES) are low-melting mixtures formed by the interaction of two or more components through hydrogen bonds, etc., usually composed of a hydrogen bond donor and a hydrogen bond acceptor. Due to their designable chemical composition, strong dissolution ability, and environmental protection characteristics, DES has become an efficient alternative solvent for metal leaching.

[0004] Regarding the report on the use of DES for leaching metals in circuit boards, Chinese patent document CN 115369250 B (application number 202211088285.X) discloses a method for recycling valuable metals in the cathode material of waste lithium-ion batteries. The method includes: mixing choline chloride with one or several combinations of L-ascorbic acid, benzenesulfonic acid, citric acid, and glycolic acid, and an auxiliary agent to obtain a deep eutectic solvent system; the auxiliary agent is one or several combinations of glycine, alanine, and cysteine; mixing the battery powder of the cathode material of waste lithium-ion batteries with the deep eutectic solvent system to obtain a leaching solution; adding oxalic acid dihydrate to the leaching solution, and after separation, washing, and drying, obtaining cobalt oxalate, nickel oxalate, and manganese oxalate.

[0005] Another example is a method for separating and recycling valuable metals in the cathode material of waste ternary lithium batteries disclosed in Chinese patent document CN 119144832 A (application number 202310712466.3). Mixing the deep eutectic solvent with the cathode material of the ternary lithium battery, leaching, and after solid-liquid separation, collecting the nickel-rich precipitate and the leaching solution; wherein, the deep eutectic solvent is composed of a leaching agent and a solvent; the leaching agent is choline chloride and tartaric acid. This application first precipitates nickel in the ternary lithium battery, preferentially separates nickel element to obtain nickel oxide, and then obtains valuable metals including cobalt, manganese, and lithium through a stepwise precipitation method to obtain cobalt oxide and manganese oxide. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for recovering metals from waste ternary lithium batteries to prepare spinel or hydrotalcite-like catalysts.

[0007] The technical solution for achieving the purpose of the present invention is a method for recovering metals from waste ternary lithium batteries to prepare catalysts, including the following steps: ①Discharge, disassemble, remove aluminum from the positive electrode sheet, and pyrolyze the positive electrode sheet of the waste ternary lithium battery to obtain positive electrode powder.

[0008] ②Prepare a deep eutectic solvent, which is composed of choline chloride, malic acid, ascorbic acid and water. The mass of pure water accounts for 30%-40% of the total weight of the deep eutectic solvent, and the molar ratio of choline chloride, malic acid, and ascorbic acid is 3-4:3-4:1.

[0009] ③Add the positive electrode powder obtained in step ① into the deep eutectic solvent prepared in step ②, with a liquid-solid ratio of 40 mL / g - 50 mL / g, and leach to obtain a leachate.

[0010] ④Add dimethylglyoxime to the leachate obtained in step ③, stir until the precipitation is complete, filter the precipitate to obtain a clear solution, and detect the elemental concentrations of Co and Mn in the mixed solution.

[0011] ⑤According to the measured elemental concentrations of Co and Mn, calculate and supplement Co salt or Mn salt to the mixed solution. After stirring evenly, add oxalic acid solution to the mixed solution. The obtained precipitate is centrifuged, separated, washed, dried, and calcined to obtain CoMn 2 O 4 spinel material.

[0012] Optionally, in step ⑤, potassium salt is also supplemented. After stirring evenly, add oxalic acid solution to the mixed solution. The obtained precipitate is centrifuged, separated, washed, dried, and calcined to obtain potassium-doped CoMn 2 O 4 spinel material. The supplemented potassium salt is one of potassium sulfate, potassium nitrate, potassium dihydrogen phosphate, and potassium acetate.

[0013] Or optionally, in step ⑤, sodium salt is also supplemented. After stirring evenly, add oxalic acid solution to the mixed solution. The obtained precipitate is centrifuged, separated, washed, dried, and calcined to obtain sodium-doped CoMn 2 O 4 spinel material. The supplemented sodium salt is one of sodium sulfate, sodium nitrate, sodium dihydrogen phosphate, and sodium acetate.

[0014] Preferably, in the deep eutectic solvent of step ②, the molar ratio of choline chloride, malic acid, and ascorbic acid is 4:4:1, and the mass of pure water accounts for 30% of the total weight of the deep eutectic solvent.

[0015] Preferably, in step ③, the positive electrode powder obtained in step ① is added to the eutectic solvent prepared in step ②, and the liquid-solid ratio is 50 mL / g.

[0016] In the above step ④, dimethylglyoxime is added to the leaching solution obtained in step ③ at a molar ratio of dimethylglyoxime:Ni = 2:1.

[0017] In the above step ⑤, the added manganese salt is manganese acetate, and the added Co salt is cobalt acetate.

[0018] The present invention also provides another method for recycling metals in waste ternary lithium batteries to prepare a catalyst, for preparing NiCoMn hydrotalcite, including the following steps: ①Discharge, disassemble, remove aluminum from the positive electrode sheet, and pyrolyze the positive electrode sheet of the waste ternary lithium battery to obtain positive electrode powder.

[0019] ②Prepare a eutectic solvent, which is composed of choline chloride, malic acid, ascorbic acid and water. The mass of pure water accounts for 30% of the total weight of the eutectic solvent, and the molar ratio of choline chloride, malic acid, and ascorbic acid is 3-4:3-4:1.

[0020] ③Add the positive electrode powder obtained in step ① to the eutectic solvent prepared in step ②, with a liquid-solid ratio of 40 mL / g - 50 mL / g, leach to obtain a leaching solution, and measure the content of metals in the leaching solution.

[0021] ④According to the measured element concentration, calculate and supplement Ni salt, Co salt or Mn salt to the mixed solution so that Ni:(Co + Mn) = 4:1, add NaOH and Na 2 CO 3 solution, adjust the pH value to 9 - 11, stir and then stand, centrifuge to obtain a precipitate, wash and dry to obtain NiCoMn hydrotalcite.

[0022] In the above step ④, the molar ratio of NaOH to Na 2 CO 3 is 3:1.

[0023] Preferably, in the eutectic solvent in step ② above, the molar ratio of choline chloride, malic acid, and ascorbic acid is 4:4:1, and the mass of pure water accounts for 30% of the total weight of the eutectic solvent; Preferably, in step ③, the positive electrode powder obtained in step ① is added to the eutectic solvent prepared in step ②, and the liquid-solid ratio is 50 mL / g.

[0024] The present invention has positive effects: The leaching solution obtained by leaching the cathode material with the deep eutectic solvent (DES) system of the present invention can be directly used for the synthesis of spinel-type or hydrotalcite-like materials without complex post-treatment. Through the synergistic effect between the components of the DES, the leaching solution retains an appropriate amount of organic ligands as structure-directing agents, effectively guiding the self-assembly process of the spinel lattice, and the product has good crystallinity.

[0025] The preparation of spinel has high requirements for the purity of raw materials. The method for recycling metals in waste ternary lithium batteries of the present invention can meet the purity requirements. Description of the Drawings

[0026] Figure 1 For the potassium-doped CoMn prepared in Example 1 2 O 4 and the sodium-doped CoMn 2 O 4 XRD patterns.

[0027] Figure 2 For the potassium-doped CoMn prepared in Example 1 2 O 4 and the sodium-doped CoMn 2 O 4 SEM images and element distribution maps.

[0028] Figure 3 For the comparison of toluene degradation effects under the synergistic catalysis of DBD alone, DBD + potassium-doped CoMn 2 O 4 and DBD + sodium-doped CoMn 2 O 4 in Test Example 1.

[0029] Figure 4 For the comparison of energy efficiency during the synergistic catalysis of toluene by DBD alone, DBD + potassium-doped CoMn 2 O 4 and DBD + sodium-doped CoMn 2 O 4 in Test Example 1.

[0030] Figure 5 For the comparison of the generation of by-product O 2 O 4 under the synergistic catalysis of DBD alone, DBD + potassium-doped CoMn 2 O 4 and DBD + sodium-doped CoMn 3 in Test Example 1.

[0031] Figure 6 For the comparison of the generation of by-product O 2 O 4 under the synergistic catalysis of DBD alone, DBD + potassium-doped CoMn 2 O4 CO under Co - catalysis 2 Comparison chart of selectivity

[0032] Figure 7 XRD pattern of NiCoMn hydrotalcite prepared for Example 2 Detailed implementation manners

[0033] The following are some of the multiple possible embodiments of the present invention, aiming to provide a basic understanding of the present invention, and not aiming to identify the key or decisive elements of the present invention or limit the scope to be protected. It is easy to understand that according to the technical solution of the present invention, without changing the essential spirit of the present invention, those of ordinary skill in the art can propose other alternative implementation manners. Therefore, the following detailed implementation manners are only exemplary descriptions of the technical solution of the present invention, and should not be regarded as the whole of the present invention or regarded as a limitation or restriction on the technical solution of the present invention.

[0034] (Example 1) In this example, recycled waste ternary lithium batteries are used to prepare potassium - doped CoMn 2 O 4 spinel material or sodium - doped CoMn 2 O 4 spinel material. The cathode materials of batteries usually include metals such as nickel, cobalt, manganese, lithium, aluminum, iron, copper, etc. In this example, after metal leaching and impurity removal, according to the concentrations of Co and Mn elements in the leaching solution, Co or Mn elements are supplemented, and K or Na elements are additionally supplemented to prepare potassium - doped or sodium - doped CoMn 2 O 4 spinel material, which specifically includes the following steps: ① Obtain the cathode powder.

[0035] Waste lithium - ion batteries contain a certain amount of residual power and need to be discharged before safe disassembly. Put the waste lithium - ion batteries into a 5% - 10% NaCl solution for 24h - 48h of discharge, take out the batteries, wash them with distilled water and dry them. When the measured voltage is below 0.5V, manual disassembly can be carried out. The cathode material, anode material, outer shell, and plastic film of the waste ternary lithium battery are obtained respectively. The disassembly is carried out in a fume hood, and protective gloves and masks should be worn.

[0036] Naturally dry the cathode material in a fume hood. After drying, cut the cathode sheet into small pieces about 20mm×20mm, and place them in an excessive sodium hydroxide (40g / L) solution at 50°C for 60min to remove aluminum (solid - liquid ratio 10g / L).

[0037] Take 2 g of the battery positive electrode sheet after aluminum removal, pyrolyze it at a high temperature of 600±20°C (600°C in this embodiment) for 4 to 6 h (5 h in this embodiment) to remove acetylene black and polyvinylidene fluoride (PVDF), take it out, cool it down, and grind it thoroughly to obtain positive electrode powder.

[0038] ②Prepare low eutectic solvent.

[0039] Choline chloride, malic acid and ascorbic acid were weighed, pure water was added, and the mixture was stirred for 25 minutes in a 60° C. water bath to prepare a low eutectic solvent.

[0040] In the prepared low eutectic solvent, the molar ratio of choline chloride, malic acid and ascorbic acid is 4:4:1, and the mass of pure water accounts for 30% of the total weight of the low eutectic solvent.

[0041] The order of steps ① and ② is not required.

[0042] ③Leaching of metals by low eutectic solvents.

[0043] The positive electrode powder obtained in step ① is added to the low eutectic solvent prepared in step ②, with a liquid-to-solid ratio of 50 mL / g (1 g of positive electrode powder is added to every 50 mL of low eutectic solvent), and the mixture is leached at 60 °C for 60 min to obtain a leachate, and the metal content in the leachate is measured by an atomic absorption spectrometer.

[0044] ④Remove impurities.

[0045] Add diacetyl oxime to the leaching solution obtained in step ③ at a molar ratio of diacetyl oxime: Ni = 2:1, and continue stirring at 60±5°C (60°C in this embodiment) for 30 minutes until precipitation is complete, and filter the precipitate to obtain a clear solution. The molar ratio of diacetyl to Ni is adjustable, and the amount added should ensure that Ni is removed as much as possible.

[0046] The obtained clear solution has a Co element concentration of 1670 mg / L and a Mn element concentration of 1812 mg / L, and is used for the preparation of a catalyst.

[0047] ⑤ Preparation of doped CoMn 2 O 4 Spinel material.

[0048] Take 50 mL of the clarified solution obtained in step ④, add 0.363 g of manganese acetate tetrahydrate and 0.028 g of potassium sulfate weighed into the solution, and stir magnetically at 80 °C; quickly add 10 mL of 0.24 mol / L oxalic acid solution to the above-mentioned mixed solution, stir magnetically at 80 °C for 0.5 h, centrifuge the reacted material at a speed of 7000 rpm for 5 min, wash the obtained precipitate three times with deionized water and then once with alcohol, then dry the precipitate at 80 °C for 12 h, and then heat it from room temperature to 400 °C at a heating rate of 5 °C / min and calcine it in air for 4 h to obtain potassium-doped CoMn 2 O 4 spinel material, grind it for use.

[0049] If it is necessary to supplement Co element, it can be supplemented by adding cobalt acetate.

[0050] The potassium salt supplemented in this step can be one of potassium sulfate, potassium nitrate, potassium dihydrogen phosphate and potassium acetate.

[0051] The potassium-doped CoMn prepared by the above operation 2 O 4 spinel material. By changing the doping element, sodium-doped CoMn can also be obtained in this step 2 O 4 spinel material, and the operation is as follows: Take 50 mL of the clarified solution obtained in step ④, add 0.363 g of manganese acetate tetrahydrate and 0.023 g of sodium sulfate weighed into the solution, and stir magnetically at 80 °C; quickly add 10 mL of 0.24 mol / L oxalic acid solution to the above-mentioned mixed solution, stir magnetically at 80 °C for 0.5 h, centrifuge the reacted material at a speed of 7000 rpm for 5 min, wash the obtained precipitate three times with deionized water and then once with alcohol, then dry the precipitate at 80 °C for 12 h, and then heat it from room temperature to 400 °C at a heating rate of 5 °C / min and calcine it in air for 4 h to obtain sodium-doped CoMn 2 O 4 spinel material, grind it for use.

[0052] The sodium salt supplemented in this step can be one of sodium sulfate, sodium nitrate, sodium dihydrogen phosphate and sodium acetate.

[0053] Potassium salt is added in step ⑤ to obtain potassium-doped CoMn 2 O 4 spinel material, and sodium salt is added to obtain sodium-doped CoMn 2 O 4 spinel material. Detect and characterize these two materials. The XRD patterns of the two materials are shown in Figure 1 , and the SEM images are shown inFigure 2 。

[0054] See Figure 1 , Figure 1 XRD characterization of 2 O 4 potassium-doped CoMn prepared in this example and 2 O 4 sodium-doped CoMn have higher peak intensities and better crystallinity, with 8 characteristic diffraction peaks at 18°, 29.1°, 32.6°, 36.3°, 44.7°, 58.6°, 60.2°, and 64.9°, corresponding to standard card #01-1126 (CoMn 2 O 4 ), indicating that the main material is CoMn 2 O 4 .

[0055] From Figure 2 the SEM images and EDS element distribution maps of 2 O 4 potassium-doped CoMn and 2 O 4 sodium-doped CoMn prepared in this example, it can be found that both spinel materials exhibit a rhombic structure. The prepared 2 O 4 potassium-doped CoMn, 2 O 4 sodium-doped CoMn materials have regular and uniform particle shapes and rich lamellar structures on the surface. EDS analysis reveals that Ni, Mn, and O elements are uniformly distributed in the catalyst.

[0056] The prepared 2 O 4 potassium-doped CoMn, 2 O 4 sodium-doped CoMn rhombic morphology is observed, with a tight structure and good organization, which is very conducive to the surface reaction.

[0057] (Example 2) In this example, waste ternary lithium batteries are recycled to prepare NiCoMn-based hydrotalcite materials, including the following steps: ① Obtain the cathode powder. The operation is the same as in Example 1.

[0058] ② Prepare the eutectic solvent. The operation is the same as in Example 1.

[0059] ③ Leach metals with the eutectic solvent.

[0060] Add the positive electrode powder obtained in step ① to the eutectic solvent prepared in step ②, with a liquid-solid ratio of 50 mL / g, leach at 60 °C for 60 min to obtain a leachate, and measure the metal content in the leachate using an atomic absorption spectrometer. The concentration of Ni element in the obtained leachate is 3420.37 mg / L, the concentration of Co element is 1670 mg / L, and the concentration of Mn element is 1812 mg / L, which is used for the preparation of the catalyst.

[0061] ④ Take 50 mL of the above leachate, add 2.355 g of nickel sulfate hexahydrate to the leachate to make the molar ratio of Ni:(Co + Mn)=4:1, and add NaOH and Na with a molar ratio of 3:1 under the condition of vigorous stirring at 60 °C 2 CO 3 solution, adjust the pH value to 9 - 11 (10 in this example), continue stirring for 2 h, stand for 12 h, then centrifuge to obtain a precipitate, wash it 3 times with ethanol and 3 times with deionized water, and then dry the precipitate at 80 °C for 8 h to obtain NiCoMn hydrotalcite, which is ground for use.

[0062] The XRD pattern of the product is shown in Figure 7 。

[0063] (Example 3) The preparation method of this example is the same as that of Example 1 in other respects, except that: In step ⑤, take 50 mL of the clear solution obtained in step ④, add the weighed 0.363 g of manganese acetate tetrahydrate to the solution, and stir magnetically at 80 °C; quickly add 10 mL of 0.24 mol / L oxalic acid solution to the above-mentioned mixed solution, stir magnetically at 80 °C for 0.5 h, centrifuge the reacted material at a rotation speed of 7000 rpm, wash the obtained precipitate three times with deionized water and then once with alcohol, then dry the precipitate at 80 °C for 12 h, and then heat it from room temperature to 400 °C at a heating rate of 5 °C / min and calcine it in air for 4 h to obtain CoMn 2 O 4 spinel material, which is ground for use.

[0064] (Example 4) The preparation method of this example is the same as that of Example 1 in other respects, except that: In the eutectic solvent prepared in step ②, the molar ratio of choline chloride, malic acid, and ascorbic acid is 3:3:1, and the mass of pure water accounts for 40% of the total weight of the eutectic solvent.

[0065] (Example 5) The preparation method of this example is the same as that of Example 1 in other respects, except that: In Step ③, the positive electrode powder obtained in Step ① is added to the eutectic solvent prepared in Step ②, and the liquid-solid ratio is 40 mL / g.

[0066] (Experimental Example 1) This test example compares the degradation rates of VOCs by dielectric barrier discharge (DBD) low-temperature plasma coupled with potassium-doped CoMn 2 O 4 synergistic catalysis, VOCs degradation by dielectric barrier discharge (DBD) low-temperature plasma coupled with sodium-doped CoMn 2 O 4 synergistic catalysis, and VOCs degradation by dielectric barrier discharge (DBD) low-temperature plasma alone. The potassium-doped CoMn 2 O 4 and sodium-doped CoMn 2 O 4 materials are prepared according to Example 1. The above three conditions are abbreviated as DBD, DBD + potassium-doped CoMn 2 O 4 and DBD + sodium-doped CoMn 2 O 4 .

[0067] The test procedure is as follows: Gas configuration: Nitrogen from a compressed steel cylinder passes through a mass flow controller (MFC) to control a certain flow rate, and then enters a stainless-steel tank containing liquid VOCs through a polytetrafluoroethylene tube with an outer diameter of 3 mm (the stainless-steel tank is temperature-controlled by a low-temperature water bath or a water bath). The VOCs vapor is carried out, and then mixed with nitrogen and oxygen controlled by two other mass flow meters in a mixer to form a VOCs gas with a stable concentration. After entering the gas mixing tank and mixing evenly, it enters the DBD discharge reactor for plasma-catalytic VOCs degradation experiments.

[0068] The experimental conditions are as follows: O 2 Concentration 4%, initial toluene concentration 300 mg / m 3 , gas flow rate is 1 L / min. Adjust the plasma energy density to 162.65 J / L, 298.87 J / L, 421.24 J / L, 563.10 J / L, and 766.35 J / L, and compare the degradation effects of DBD, DBD + potassium-doped CoMn 2 O 4 and DBD + sodium-doped CoMn 2 O 4 on toluene.

[0069] The experimental results are shown in Figures 3 to 6 . In the figure, DBD + potassium-doped CoMn spinel corresponds to DBD + potassium-doped CoMn 2 O4 , DBD + sodium-doped CoMn spinel corresponds to DBD + sodium-doped CoMn 2 O 4 .

[0070] See Figure 3 , the catalytic system of DBD + catalyst has a higher toluene removal efficiency than the single DBD system. When the SED increases from 162.65 J / L to 766.35 J / L, the degradation efficiency of the single DBD system increases from 34.17% to 86.86%, while for DBD + sodium-doped CoMn 2 O 4 and DBD + potassium-doped CoMn 2 O 4 , when the SED increases from 162.65 J / L to 766.35 J / L, the toluene removal rates increase from 43.45% and 59.61% to 92.02% and 94.76% respectively. At the same SED value, potassium-doped CoMn 2 O 4 catalyst shows better catalytic performance.

[0071] See Figure 4 , as the energy density increases, the energy efficiency shows a decreasing trend. At the same SED, the energy efficiency of the DBD catalytic system is significantly higher than that of the single DBD degradation. When the SED is 162.65 J / L, the energy efficiency value of the single DBD system is 9.68 g·kWh -1 , while for DBD + sodium-doped CoMn 2 O 4 and DBD + potassium-doped CoMn 2 O 4 the energy efficiency values are 12.33 g·kWh -1 and 16.88 g·kWh -1 .

[0072] See Figure 5 , O 3 concentration decreases with the increase of SED. When the SED is 766.35 J / L, the O 3 concentration in the single DBD system is about 105 mg·m -3 , while for DBD + sodium-doped CoMn 2 O 4 and DBD + potassium-doped CoMn 2 O 4 , O 3 concentration decreases to 12.86 mg·m -3 and 32.14 mg·m -3 . From low to high energy density, sodium-doped CoMn 2 O4 The O generated when the catalyst participates in the DBD catalytic process 3 is always lower than that of potassium-doped CoMn 2 O 4 catalyst.

[0073] See Figure 6 , CO 2 selectivity increases with the increase of SED. When SED is 766.35 J / L, the CO 2 selectivity in the single DBD system is about 36.63%, while for DBD + sodium-doped CoMn 2 O 4 and DBD + potassium-doped CoMn 2 O 4 systems, the CO2 selectivities increase to 56.63% and 59.17% respectively. As the energy density increases from low to high, the CO 2 O 4 selectivity when the sodium-doped CoMn 2 catalyst participates in the DBD catalytic process is always lower than that of potassium-doped CoMn 2 O 4 catalyst, indicating that the potassium-doped CoMn 2 O 4 catalyst exhibits higher CO 2 selectivity and higher catalytic performance.

Claims

1. A method for recovering metals from waste ternary lithium batteries to prepare catalysts, characterized in that The following steps are involved: ①Discharge and disassemble the waste ternary lithium batteries, remove aluminum from the positive electrode sheets, and pyrolyze the positive electrode sheets to obtain positive electrode powder; ② preparing a low eutectic solvent, wherein the low eutectic solvent is composed of choline chloride, malic acid, ascorbic acid and water, the mass of pure water accounts for 30%-40% of the total weight of the low eutectic solvent, and the molar ratio of choline chloride, malic acid and ascorbic acid is 3-4:3-4:1; ③ Add the cathode powder obtained in step ① to the low eutectic solvent prepared in step ②, with a liquid-to-solid ratio of 40 mL / g-50 mL / g, and leaching to obtain a leachate; ④ Add diacetyl oxime to the leaching solution obtained in step ③, stir until the precipitation is complete, filter the precipitate to obtain a clarified solution, and detect the element concentrations of Co and Mn in the mixed solution; ⑤ According to the measured element concentrations of Co and Mn, Co salt or Mn salt is added to the mixed solution after calculation, and oxalic acid solution is added to the mixed solution after stirring evenly. The obtained precipitate is centrifuged, washed, dried, and calcined to obtain CoMn2O4 spinel material.

2. The method for recovering metals from waste ternary lithium batteries to prepare catalysts according to claim 1, characterized in that: In step ⑤, potassium salt is also added, and after stirring evenly, oxalic acid solution is added to the mixed solution. The obtained precipitate is centrifuged, washed, dried, and calcined to obtain potassium-doped CoMn2O4 spinel material.

3. The method for recovering metals from waste ternary lithium batteries to prepare catalysts according to claim 1, characterized in that: In step ⑤, sodium salt is also added, and after stirring evenly, oxalic acid solution is added to the mixed solution. The obtained precipitate is centrifuged, washed, dried, and calcined to obtain sodium-doped CoMn2O4 spinel material.

4. The method for recovering metals from waste ternary lithium batteries to prepare catalysts according to claim 1, characterized in that: In the low eutectic solvent of step ②, the molar ratio of choline chloride, malic acid and ascorbic acid is 4:4:1, and the mass of pure water accounts for 30% of the total weight of the low eutectic solvent.

5. The method for recovering metals from waste ternary lithium batteries to prepare catalysts according to claim 1, characterized in that: In step ③, the positive electrode powder obtained in step ① is added to the low eutectic solvent prepared in step ②, and the liquid-to-solid ratio is 50 mL / g.

6. The method for recovering metals from waste ternary lithium batteries to prepare catalysts according to claim 1, characterized in that: In step ④, a precipitant, dimethylglyoxime, is added to the leachate obtained in step ③ at a molar ratio of dimethylglyoxime: Ni=2:

1.

7. The method for recovering metals from waste ternary lithium batteries to prepare catalysts according to claim 1, characterized in that: In step ⑤, the supplemented manganese salt is manganese acetate, and the supplemented Co salt is cobalt acetate.

8. A method for recovering metals from waste ternary lithium batteries to prepare catalysts, characterized in that The following steps are involved: ①Discharge and disassemble the waste ternary lithium batteries, remove aluminum from the positive electrode sheets, and pyrolyze the positive electrode sheets to obtain positive electrode powder; ② preparing a low eutectic solvent, wherein the low eutectic solvent is composed of choline chloride, malic acid, ascorbic acid and water, the mass of pure water accounts for 30% of the total weight of the low eutectic solvent, and the molar ratio of choline chloride, malic acid and ascorbic acid is 3-4:3-4:1; ③ Add the positive electrode powder obtained in step ① to the low eutectic solvent prepared in step ②, with a liquid-to-solid ratio of 40 mL / g-50 mL / g, leaching to obtain a leachate, and measuring the metal content in the leachate; ④ According to the measured element concentration, Ni salt, Co salt or Mn salt is added to the mixed solution after calculation so that Ni: (Co + Mn) = 4:1, NaOH and Na2CO3 solution are added, the pH value is adjusted to 9-11, stirred and allowed to stand, centrifuged to obtain a precipitate, washed and dried to obtain NiCoMn hydrotalcite.

9. The method for recovering metals from waste ternary lithium batteries to prepare catalysts according to claim 8, characterized in that: In step ④, the molar ratio of NaOH to Na2CO3 is 3:

1.

10. The method for recovering metals from waste ternary lithium batteries to prepare catalysts according to claim 8, characterized in that: In the low eutectic solvent of step ②, the molar ratio of choline chloride, malic acid and ascorbic acid is 4:4:1, and the mass of pure water accounts for 30% of the total weight of the low eutectic solvent; In step ③, the positive electrode powder obtained in step ① is added to the low eutectic solvent prepared in step ②, and the liquid-to-solid ratio is 50 mL / g.

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