Method for efficiently leaching cathode powder of waste batteries using hydrogel and bacteria

Abstract

The invention discloses a method for efficiently leaching waste battery positive electrode powder by using hydrogel to assist bacteria, belonging to the field of resource recovery technology. The invention utilizes hydrogel to assist bacteria to leach valuable metal elements from waste LIBs. The bacteria include L. plants and / or L. acidophilus , the hydrogel is prepared by polyvinyl alcohol and agarose. The present invention creatively applies hydrogel in the bioleaching process, effectively increases the leaching percentage of valuable metals in waste LIBs, and avoids the use of inorganic acid at the same time. Compared with the traditional chemical leaching technology, the method of the present invention has obvious advantages in operational safety and effectively avoids the risk of secondary pollution to the environment. By using microorganisms, not only the efficient recovery of metal resources in the battery is achieved, but also the environmental friendliness of the whole process is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of resource recovery, and in particular relates to a method for efficiently leaching valuable metal elements in positive electrode powder of waste batteries by utilizing hydrogel in collaboration with bacteria. Background Art

[0002] In recent years, the rapid development of the electric vehicle industry and energy storage systems has led to a sharp increase in the use of lithium-ion batteries (LIBs), and the treatment of scrapped batteries has become a key issue. Compared with traditional recycling methods, microbial leaching technology has the advantages of low energy consumption and green environmental protection, so it has great application potential and market prospects. Despite this, bioleaching technology still faces some challenges. First, the low leaching efficiency limits its widespread application in industrial-scale applications. In addition, the composition of different batteries varies greatly, which puts higher requirements on the adaptability of leaching bacteria. At present, bioleaching mainly relies on strong acidophilic bacteria. This process will produce a large amount of acidic wastewater, which adds additional treatment costs. In order to reduce environmental impact and reduce costs, it is necessary to explore mild acidophilic bacteria. Previous research results show that Lactobacillus plantarum ( Lactobacillus plantarum ) and Lactobacillus acidophilus ( Lactobacillus acidophilus ) can achieve higher metal leaching percentages in milder acidic environments and are therefore selected for bioleaching.

[0003] However, the efficiency of bioleaching is not only related to the selection of bacterial strains, but also affected by a variety of environmental factors, including solid-liquid ratio, pH value, temperature and spatial state. These factors act together on the metabolic activities of microorganisms, thereby affecting the leaching efficiency. Therefore, in order to promote the industrialization of bioleaching technology, the key lies in optimizing these operating conditions and deeply exploring the leaching mechanism. By improving the growth environment of microorganisms and adjusting process parameters, the leaching efficiency can be improved, the cost can be reduced, and ultimately the efficient and environmentally friendly recycling of waste LIBs can be achieved.

[0004] During the bioleaching process, microorganisms promote the dissolution and release of valuable metals in waste LIBs through their metabolic activities, such as redox reactions, production of organic acids and extracellular polymers (EPS). Previous studies have shown that bacteria can use biogenic organic acids or extracellular secretions to leach valuable metals from waste LIBs by acid dissolution and / or redox (Sedlakova-Kadukova et al., 2020).

[0005] Hydrogels are a class of polymer network materials that can absorb and retain large amounts of water while maintaining a solid state. Previous studies have shown that hydrogels can not only serve as a matrix for microbial growth, but also as a medium for the extraction and separation of metals. Due to their good biocompatibility and special pore structure, they have attracted much attention in microbial metallurgy (Condi Mainardi et al., 2020). However, there are currently no reports on the use of hydrogels in microbial leaching of waste LIBs. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention provides a method for efficiently leaching valuable metals in waste LIBs powder by using hydrogel and bacteria, aiming to increase the leaching percentage of valuable metals by bacteria under a certain solid-liquid ratio, explore the leaching mechanism, and provide an effective means for microbial recovery of valuable metals.

[0007] The technical solution of the present invention is a method for efficiently leaching the positive electrode powder of waste batteries by using hydrogel and bacteria. The waste batteries refer to typical waste LIBs, including waste lithium iron phosphate batteries (LFP), lithium nickel manganese cobalt oxide batteries (NCM), lithium nickel cobalt aluminum oxide batteries (NCA) and lithium cobalt oxide batteries (LCO); the bacteria include L. plantarum and L. acidophilus ; The hydrogel is prepared by polyvinyl alcohol and agarose.

[0008] A method for efficiently leaching waste battery positive electrode powder by using hydrogel and bacteria, specifically comprising the following steps:

[0009] Step 1: Preparation of battery powder

[0010] Typical waste LIBs were selected, and these waste batteries were discharged in NaCl solution and then dried. After complete drying, the batteries were disassembled and the positive electrodes were separated. The positive electrode sheets were cut into 1cm×1cm square pieces, immersed in N-methylpyrrolidone (NMP) to dissolve and remove the binder, and then washed with deionized water until the pH of the solution was 7.5, and then placed in an oven for drying again. Finally, a powder grinder was used to crush the pieces, and the powder was passed through a 100-mesh sieve to obtain waste battery powder, which was stored in a light-proof and dry environment.

[0011] Step 2: Acclimation of bacteria

[0012] use L. plantarum and / or L. acidophilus Conduct bioleaching experiments; inoculate the bacteria into MRS medium, add the waste battery powder obtained in step 1, and culture them in an incubator until the cells enter the logarithmic growth phase, that is, the number of cells increases to 10 8 When the concentration of the powder reached 1.5 g / mL, the inoculum was continued to be subcultured at 5% (v / v). For the same powder concentration, the subculture operation was performed twice; then the powder concentration was increased by 0.5 g / L, and the operation was repeated until the powder concentration increased to 5.0 g / L, and it was subcultured twice in the medium of MRS without cell powder, and finally the bacterial culture was prepared and stored in a -80℃ refrigerator for subsequent use.

[0013] Step 3: Preparation of MRS medium containing hydrogel

[0014] Add poly (vinyl alcohol), PVA and agarose (AG) to the MRS medium in step 2 and sterilize. After sterilization, place it in a water bath to keep warm. When the temperature reaches 36℃-38℃, the MRS medium containing hydrogel is obtained for subsequent leaching experiments.

[0015] Step 4: Experiment on efficient leaching of valuable metals from waste battery powder by hydrogel-assisted bacteria

[0016] The bacterial solution in step 2 and the waste battery powder in step 1 were added to the MRS medium and the MRS medium containing the hydrogel in step 3, respectively, and shaken to mix them evenly. Then, they were placed in a 37°C constant temperature and humidity incubator for static culture. The concentrations of bacteria and waste battery powder were 2.5×10 7 cells / mL and 5.0 g / L. Samples were taken at regular intervals, and the pH value was measured using a pH meter. The samples were then filtered through a 0.22 μm water system microporous membrane to obtain the filtrate. The metal ion concentration in the filtrate was then measured and its leaching percentage was calculated.

[0017] In step 1, the waste lithium-ion battery is discharged in a 10% (m / v) NaCl solution for 24h-48h, and then dried in an oven at 40°C-60°C for 48h-60h. After complete drying, the battery is disassembled and the positive electrode is separated. The 10% (m / v) NaCl solution means that 100mL of the solution contains 10g of NaCl.

[0018] In step 2, the cells are cultured in an incubator for 12-16 hours at a temperature of 37°C-40°C. When adding powder, the initial cell density of the bacteria should be 2×10 7cells / mL; when the cells enter the logarithmic growth phase, that is, the number of cells increases to 10 8 When the cell count reached 10 cells / mL, the cells were subcultured at a 5% (v / v) inoculum volume.

[0019] In step 2, the components of the MRS culture medium are: 10.0 g / L peptone, 5.0 g / L beef extract powder, 4.0 g / L yeast extract powder, 20.0 g / L glucose, 2.0 g / L diammonium hydrogen citrate, 5.0 g / L CH3COONa, 0.2 g / L MgSO4, 0.05 g / L MnSO4, and 1.0 g / L Tween 80.

[0020] In the step 3, polyvinyl alcohol and agarose are added to the MRS medium in step 2 to make their final concentrations 5% (w / v) and 1% (w / v), respectively; then sterilized at 118°C for 20 minutes, and after sterilization, placed in a 37°C water bath for insulation, and the MRS medium containing the hydrogel is obtained when the temperature reaches 36°C-38°C.

[0021] The key points of the present invention are: first, the innovative design of hydrogel-assisted leaching. The unique structure and properties of the hydrogel synergize with bacteria to improve bacterial activity by regulating the local environment. Its three-dimensional network structure provides a stable environment for lactobacilli and helps to diffuse substances; second, under a certain solid-liquid ratio environment, the hydrogel can overcome the problems of traditional leaching, promote material transfer, and optimize the interaction between microorganisms and cathode powder to improve leaching efficiency; third, the mechanism of action of hydrogel-assisted leaching is deeply explored, and research is conducted from multiple aspects of chemistry and biology to provide a theoretical basis for optimizing the biological leaching method to promote industrialization and large-scale application.

[0022] Compared with the prior art, the method of the present invention has the following beneficial effects:

[0023] 1. The creative application of hydrogel in the bioleaching process effectively increased the leaching percentage of valuable metals in waste LIBs.

[0024] 2. This method avoids the use of inorganic acid and maintains a pH value of about 4, which is a relatively mild condition. Compared with traditional chemical leaching technology, the method of the present invention has obvious advantages in operational safety and effectively avoids the risk of secondary pollution to the environment.

[0025] 3. By adopting microorganisms such as Lactobacillus plantarum and Lactobacillus acidophilus, not only the efficient recovery of metal resources in the battery is achieved, but also the environmental friendliness of the entire process is ensured. DETAILED DESCRIPTION

[0026] The embodiment of the present invention selects typical waste LIBs, including waste lithium iron phosphate batteries (LFP), lithium nickel manganese cobalt oxide batteries (NCM), lithium nickel cobalt aluminum oxide batteries (NCA) and lithium cobalt oxide batteries (LCO). These waste batteries are discharged in a 10% (m / v) NaCl solution for 24h-48h, and then dried in an oven at 40℃-60℃ for 48h-60h. After complete drying, the battery is disassembled and the positive electrode is separated. The positive electrode sheet is cut into 1cm×1cm square pieces, soaked in N-methylpyrrolidone (NMP) to dissolve and remove the binder, and then washed with deionized water for more than 5 times until the pH of the solution is 7.5, and then placed in an oven for drying again. Finally, a powdering machine is used to crush the powder, and the powder is passed through a 100-mesh sieve to obtain waste battery powder, which is stored in a light-proof and dry environment.

[0027] Example 1

[0028] A method using hydrogel synergistic L. plantarum The method for leaching the positive electrode powder of waste NCM batteries, the specific steps are as follows:

[0029] Step 1: Prepare MRS medium by adding 10 g peptone (10.0 g / L), 5.0 g beef extract powder (5.0 g / L), 4.0 g yeast extract powder (4.0 g / L), 20.0 g glucose (20.0 g / L), 2.0 g C6H 14 N2O7 (2.0g / L), 5.0gCH3COONa (5.0g / L), 0.2g MgSO4 (0.2g / L), 0.05g MnSO4 (0.05g / L), 1.0g C 24 H 44 O6 (1.0 g / L); sterilize the solution at 118°C for 15 min to obtain MRS medium, which was cooled for later use.

[0030] Step 2: L. plantarum cultivation of L. plantarum Inoculate into MRS medium, add waste NCM battery powder, and culture in an incubator at 37℃-40℃. When adding powder, ensure that the initial cell density of bacteria is 2×10 7 cells / mL; when the cells enter the logarithmic growth phase, that is, the number of cells increases to 10 8When the concentration of cells / mL reaches 5%, continue to subculture at an inoculum volume of 5% (v / v). For the same powder concentration, perform two subculture operations; then increase the powder concentration by 0.5g / L in stages, and repeat the operation until the powder concentration increases to 5.0g / L. Subculture it twice in the MRS medium without cell powder, and finally prepare the bacterial culture, store it in a -80℃ refrigerator, and complete the domestication of the bacteria. Inoculate the domesticated bacterial culture culture into the MRS (200mL) medium in step 1, shake it evenly, and all the above operations are performed in a clean bench. Then place it in an incubator for static culture at 37℃, and take it out after 14h for use.

[0031] Step 3: Add 1g PVA and 0.2g AG to 200mL MRS medium to make the final concentrations 5% (w / v) and 1% (w / v), respectively. Then sterilize at 118℃ for 20min, and place in a 37℃ water bath to keep warm. When the temperature reaches about 37℃, the MRS medium containing hydrogel is obtained for subsequent leaching experiments.

[0032] Step 4: Collect the cells grown to the logarithmic growth phase in step 2 L. plantarum The bacterial solution was centrifuged (10000rpm, 3min), resuspended in the MRS medium in step 1 and the MRS medium containing hydrogel prepared in step 3, mixed evenly, then the waste NCM battery powder was added, mixed evenly again, and finally placed in a 37℃ constant temperature and humidity incubator for static culture. The concentration of bacteria and the concentration of waste battery powder were 2.5×10 7 cells / mL and 5.0g / L. Samples were taken on days 0, 1, 2, 3, 4, 6, 9, 12, 13, 14 and 15, respectively, and the pH value of the monitoring system was around 4. The solution was then filtered and the filtrate was diluted to a certain multiple with 1% dilute nitric acid; the metal ion concentration in the solution was then measured using inductively coupled plasma atomic emission spectroscopy (ICP-OES), and the bioleaching percentage was finally calculated.

[0033] In Example 1, the hydrogel assisted L. plantarum The results of leaching spent NCM battery powder are as follows: when the culture medium does not contain hydrogel, the leaching is carried out for 14 days at a solid-liquid ratio of 5.0 g / L. L. plantarum Li in waste NCM battery powder 、 Ni 、 The leaching percentages of Co and Mn were 60.7%, 54.6%, 57.2% and 51.6%, respectively; while in the MRS culture environment containing hydrogel, L. plantarumThe leaching percentages of Li, Ni, Co and Mn were increased to 79.3%, 78.4%, 74.5% and 72.4% respectively, and the leaching percentages were increased by 18.6%, 23.8%, 17.3% and 20.8% respectively. L. plantarum The leaching percentage of Ni and Mn was increased most significantly, with the increase rates of Ni and Mn being 1.3 times that of Li and 1.4 times that of Co. The above results show that hydrogel can significantly improve L. plantarum Leaching percentage of valuable metals in spent NCM battery powder.

[0034] Example 2

[0035] A method using hydrogel synergistic L. plantarum The method for leaching the positive electrode powder of waste LFP batteries is as follows:

[0036] Step 1: Prepare MRS medium as described in step 1 of Example 1.

[0037] Step 2: Cultivate bacteria as in step 2 of Example 1.

[0038] Step 3: As in step 3 of Example 1, prepare MRS culture medium containing hydrogel.

[0039] Step 4: As shown in step 4 of Example 1, valuable metals in LFP are leached.

[0040] In Example 2, the hydrogel assisted L. plantarum The results of leaching spent LFP battery powder are as follows: when the culture medium does not contain hydrogel, the leaching is carried out for 14 days at a solid-liquid ratio of 5.0 g / L. L. plantarum The leaching percentages of Li and Fe in waste LFP powder can reach 60.7% and 50.6% respectively; while in the MRS culture environment containing hydrogel, L. plantarum The leaching percentages of Li and Fe were 89% and 22.4%, respectively, and the leaching percentage of Li increased by 28.3%, indicating that the hydrogel can significantly improve L. plantarum It has high selectivity for the recovery rate of Li from waste LFP battery powder.

[0041] Example 3

[0042] A method using hydrogel synergistic L. plantarum The method for leaching the positive electrode powder of waste NCA batteries is as follows:

[0043] Step 1: Prepare MRS medium as described in step 1 of Example 1.

[0044] Step 2: Cultivate bacteria as in step 2 of Example 1.

[0045] Step 3: As in step 3 of Example 1, prepare MRS culture medium containing hydrogel.

[0046] Step 4: As shown in step 4 of Example 1, valuable metals in NCA are leached.

[0047] In Example 3, the hydrogel assisted L. plantarum The results of leaching spent NCA battery powder are as follows: when the culture medium does not contain hydrogel, the leaching is carried out for 14 days at a solid-liquid ratio of 5.0 g / L. L. plantarum The leaching percentages of Li, Ni, Co and Al metal ions in waste NCA powder can reach 59.7%, 60.2%, 60.3% and 64.7% respectively; in the MRS culture environment containing hydrogel, L. plantarum The leaching percentages of Li, Ni, Co and Al were increased to 80.5%, 77.1%, 79.5% and 76.7% respectively, and the leaching percentages were increased by 20.8%, 16.9%, 19.2% and 12.0% respectively. L. plantarum The leaching percentage of Li and Co increased most significantly, indicating that the hydrogel can significantly improve L. plantarum Leaching percentage of valuable metals in spent NCA battery powder.

[0048] Example 4

[0049] A method using hydrogel synergistic L. plantarum The method for leaching the positive electrode powder of waste LCO batteries, the specific steps are as follows:

[0050] Step 1: Prepare MRS medium as described in step 1 of Example 1.

[0051] Step 2: Cultivate bacteria as in step 2 of Example 1.

[0052] Step 3: As in step 3 of Example 1, prepare MRS culture medium containing hydrogel.

[0053] Step 4: As shown in step 4 of Example 1, valuable metals in LCO are leached.

[0054] In Example 4, the hydrogel assisted L. plantarum The results of leaching spent LCO battery powder are as follows: when the culture medium does not contain hydrogel, the leaching is carried out for 14 days at a solid-liquid ratio of 5.0 g / L. L. plantarum The leaching percentages of Li and Co in the waste LCO powder were 68.3% and 60.9%. L. plantarum The leaching percentages of Li and Co were increased to 87.5% and 77.4%, respectively, and the leaching percentages increased by 19.2% and 16.5%, respectively, indicating that the hydrogel can significantly improve L. plantarumLeaching percentage of valuable metals in spent LCO battery powder.

[0055] Example 5

[0056] A hydrogel-assisted L. acidophilus The method for leaching the positive electrode powder of waste NCM batteries, the specific steps are as follows:

[0057] Step 1: Prepare MRS medium as in step 1 of Example 1.

[0058] Step 2: Cultivate bacteria as in step 2 of Example 1, except that the bacteria used in Example 5 are L. acidophilus The acclimatization and cultivation method is the same as step 2 of Example 1.

[0059] Step 3: As in step 3 of Example 1, prepare MRS culture medium containing hydrogel.

[0060] Step 4: As in step 4 of Example 1, valuable metals in NCM are leached. L. acidophilus The bacterial solution was centrifuged (10000rpm, 3min), resuspended in the MRS medium in step 1 and the MRS medium containing hydrogel prepared in step 3, mixed evenly, and finally added with the waste NCM battery powder, mixed evenly again, and finally placed in a 37℃ incubator for static culture. The concentration of bacteria and the concentration of waste battery powder were 2.5×10 7 cells / mL and 5.0 g / L. Samples were taken at intervals to determine the concentration of metal ions leached by bacteria in the solution to calculate the leaching percentage. L. acidophilus The results of leaching spent NCM battery powder showed that when the culture medium did not contain hydrogel, the solid-liquid ratio was 5.0 g / L for 14 days. L. acidophilus The leaching percentages of Li, Ni, Co and Mn in waste NCM powder were 61.7%, 53.6%, 50.1% and 59.8% respectively. L. acidophilus The leaching percentages of Li, Ni, Co and Mn were increased to 83.1%, 73.2%, 70.4% and 75.1%, respectively, and the leaching percentages were increased by 21.4%, 19.6%, 20.3% and 15.3%, respectively. The above results show that hydrogel can significantly improve L. acidophilus Leaching percentage of valuable metals in spent NCM battery powder.

[0061] Example 6

[0062] A hydrogel-assisted L. acidophilusThe method for leaching the positive electrode powder of waste LFP batteries is as follows:

[0063] Step 1: Prepare MRS medium as in step 1 of Example 1.

[0064] Step 2: Cultivate bacteria as in step 2 of Example 1, except that the bacteria used in Example 6 are L. acidophilus The acclimatization and cultivation method is the same as step 2 of Example 1.

[0065] Step 3: As in step 3 of Example 1, prepare MRS culture medium containing hydrogel.

[0066] Step 4: As in step 4 of Example 1, valuable metals in LPF are leached. L. acidophilus The results of leaching spent LFP battery powder showed that when the culture medium did not contain hydrogel, the solid-liquid ratio was 5.0 g / L for 24 days. L. acidophilus The leaching percentages of Li and Fe metal ions in the waste LFP powder were 60.8% and 60.2% respectively; while in the MRS culture environment containing hydrogel, L. acidophilus The leaching percentages of Li and Fe were 83.4% and 2.3% respectively, the leaching percentage of Li increased by 22.6%, and the leaching percentage of Fe decreased by 57.9%. L. acidophilus Highly selective leaching of Li.

[0067] Example 7

[0068] A hydrogel-assisted L. acidophilus The method for leaching the positive electrode powder of waste NCA batteries is as follows:

[0069] Step 1: Prepare MRS medium as in step 1 of Example 1.

[0070] Step 2: Cultivate bacteria as in step 2 of Example 1, except that the bacteria used in Example 7 are L. acidophilus The acclimatization and cultivation method is the same as step 2 of Example 1.

[0071] Step 3: As in step 3 of Example 1, prepare MRS culture medium containing hydrogel.

[0072] Step 4: As in step 4 of Example 5, valuable metals in the NCA powder are leached.

[0073] In Example 7, the hydrogel assisted L. acidophilus The spent NCA battery powder was leached as follows: when the culture medium did not contain hydrogel, the leaching was carried out for 16 days at a solid-liquid ratio of 5.0 g / L. L. acidophilus The leaching percentages of Li, Ni, Co and Al metal ions in the waste NCA powder can reach 60.4%, 59.3%, 57.3% and 65.2% respectively; while in the MRS culture environment containing hydrogel, L. acidophilus The leaching percentages of Li, Ni, Co and Al were increased to 69.6%, 78.2%, 73.1% and 74.3%, respectively, and the leaching percentages were increased by 9.2%, 18.9%, 15.8% and 9.1%, respectively, indicating that the hydrogel can significantly improve L. acidophilus Leaching percentage of valuable metals in spent NCA battery powder.

[0074] Example 8

[0075] A hydrogel assisted L. acidophilus The method for leaching the positive electrode powder of waste LCO batteries, the specific steps are as follows:

[0076] Step 1: Prepare MRS medium as in step 1 of Example 1.

[0077] Step 2: Cultivate bacteria as in step 2 of Example 1, except that the bacteria used in Example 8 are L. acidophilus The acclimatization and cultivation method is the same as step 2 of Example 1.

[0078] Step 3: As in step 3 of Example 1, prepare MRS culture medium containing hydrogel.

[0079] Step 4: As in step 4 of Example 5, valuable metals in LCO are leached.

[0080] In Example 8, the hydrogel assisted L. acidophilus The results of leaching spent LCO battery powder are as follows: when the culture medium does not contain hydrogel, the leaching is carried out for 14 days at a solid-liquid ratio of 5.0 g / L. L. acidophilus The leaching percentages of Li and Co in the waste LCO powder were 56.4% and 57.3%, respectively; while in the MRS culture environment containing hydrogel, L. acidophilus The leaching percentages of Li and Co were increased to 65.3% and 77.3%, respectively, and the leaching percentages were increased by 8.9% and 20.0%, respectively, indicating that the hydrogel can significantly improve L. acidophilus Leaching percentage of valuable metals in spent LCO battery powder.

Claims

1. A method for efficiently leaching the positive electrode powder of waste batteries by using hydrogel and bacteria, characterized in that: The following steps are involved: Step 1: Preparation of battery powder Select waste lithium-ion batteries, discharge them in a NaCl solution, and then dry them. After they are completely dried, disassemble the batteries and separate the positive electrodes; cut the positive electrode sheets into small square pieces, soak them in N-methylpyrrolidone to dissolve and remove the binder, and then wash them with deionized water until the pH of the solution is 7.5, and then put them into an oven for drying again; finally, crush and pulverize them, and pass the powder through a 100-mesh sieve to obtain waste battery powder, which is stored in a light-proof and dry environment; the waste batteries include waste lithium iron phosphate batteries, nickel cobalt manganese oxide batteries, nickel cobalt aluminum oxide batteries, and lithium cobalt oxide batteries; Step 2: Acclimation of bacteria use L. plantarum and / or L. acidophilus Conduct bioleaching experiments; inoculate the bacteria into MRS medium, add the waste battery powder obtained in step 1, and culture them in an incubator until the cells enter the logarithmic growth phase, that is, the number of cells increases to 10 8 When the concentration of the powder reached 5.0 g / mL, the cells were subcultured at 5% inoculation volume. The subculture was repeated twice at the same powder concentration. The powder concentration was then increased by 0.5 g / L in a cycle until the powder concentration reached 5.0 g / L. The cells were subcultured twice in the MRS medium without cell powder. Finally, the culture medium was prepared and stored in a -80°C refrigerator for subsequent use. Step 3: Preparation of MRS medium containing hydrogel Add polyvinyl alcohol and agarose to the MRS medium in step 2 to make final concentrations of 5% and 1%, respectively, and then sterilize at 118°C for 20 minutes. After sterilization, place in a 37°C water bath to keep warm. When the temperature reaches 36-38°C, obtain the MRS medium containing the hydrogel; Step 4: Experiment on efficient leaching of valuable metals from waste battery powder by hydrogel-assisted bacteria The bacterial solution in step 2 and the waste battery powder in step 1 were added to the MRS medium containing the hydrogel in step 3, shaken to mix evenly, and then placed in a 37°C constant temperature and humidity incubator for static culture. The concentrations of bacteria and waste battery powder were 2.5×10 7 cells / mL and 5.0 g / L; sampling was performed at intervals, and the pH value was determined using a pH meter, followed by filtration with a 0.22 μm water system microporous filter membrane to obtain the filtrate, and then the metal ion concentration in the filtrate was determined and its leaching percentage was calculated.

2. The method of using hydrogel to cooperate with bacteria to efficiently leaching the positive electrode powder of waste batteries according to claim 1 is characterized in that: In the step 1, the waste lithium-ion battery is discharged in a 10% NaCl solution for 24-48 hours, and then dried in an oven at 40-60° C. for 48-60 hours. After being completely dried, the battery is disassembled and the positive electrode is separated.

3. The method of using hydrogel and bacteria to efficiently leach cathode powder from waste batteries according to claim 1, characterized in that: In step 2, using L. plantarum and / or L. acidophilus Conduct a bioleaching experiment; inoculate the bacteria into the MRS medium, add the waste battery powder obtained in step 1, and culture in an incubator for 12-16 hours at a temperature of 37-40°C; when adding the powder, ensure that the initial cell density of the bacteria is 2×10 7 cells / mL; when the cells enter the logarithmic growth phase, that is, the number of cells increases to 10 8 When it reaches cells / mL, continue to subculture at an inoculum size of 5%; perform two subculture operations for the same powder concentration; then increase the powder concentration by 0.5 g / L in stages, and repeat the operation until the powder concentration increases to 5.0 g / L, subculture it twice in the culture medium of MRS without cell powder, and finally prepare the bacterial culture medium and store it in a -80°C refrigerator for subsequent use.

4. The method of claim 1 for efficiently leaching the positive electrode powder of waste batteries by using hydrogel in collaboration with bacteria, characterized in that: The MRS culture medium components are: 10.0 g / L peptone, 5.0 g / L beef extract powder, 4.0 g / L yeast extract powder, 20.0 g / L glucose, 2.0 g / L diammonium hydrogen citrate, 5.0 g / L CH3COONa, 0.2 g / L MgSO4, 0.05 g / L MnSO4, and 1.0 g / L Tween 80.