A method for extracting waste LiNi from Lactobacillus plantarum x Mn y Co 1-x-y O2 battery method

Abstract

A method for extracting waste LiNi from Lactobacillus plantarum x Mn y Co 1‑x‑y The invention discloses a method for leaching waste LiNi O2 battery by Lactobacillus plantarum. x Mn y Co 1‑x‑y The method of O2 battery includes four steps: preparation of battery powder, domestication of bacteria, bioleaching and testing of the results. x Mn y Co 1‑x‑y O2 battery (NMC) is a type of ternary polymer lithium-ion battery (LIB); the present invention aims to solve the current problems of recycling waste LIB batteries, such as being environmentally unfriendly and having high energy consumption; Lactobacillus plantarum, which is harmless to the environment and human body, is used to extract valuable metals from the positive electrode materials of waste NMC batteries, thereby improving the strong acid or strong alkaline wastewater generated in previous methods and the economic and environmental problems caused by the biological leaching process.

Description

Technical Field

[0001] The invention belongs to the technical field of resource recovery and particularly relates to a method for leaching waste LiNi by Lactobacillus plantarum x Mn y Co 1-x-y O2 battery method. Background Art

[0002] As LiNi in ternary polymer lithium-ion battery (LIB) x Mn y Co 1-x-y O2 (NMC) batteries are widely used in electric vehicles, new energy vehicles, energy storage systems and other equipment due to their high energy density, long cycle life, fast charge and discharge cycles and high safety performance. Due to the vigorous development of the new energy industry, the production and use of NMC batteries are still growing. The average service life of NMC on the market is about 5-8 years, and the number of waste lithium-ion batteries that need to be recycled has also increased accordingly. The recycling of waste NMC batteries can not only alleviate the shortage of heavy metal resources, but also reduce its harm to the environment. Therefore, the recycling of waste NMC batteries has become an urgent problem to be solved.

[0003] At present, there are three main methods for recycling waste LIBs: direct recycling, pyrometallurgy and hydrometallurgy. The direct recycling method mainly retains the original structure and morphology of the battery, directly repairs its defects, and can be used directly after regeneration, avoiding the subsequent purification steps with long cycles and high costs. Pyrometallurgy mainly adopts high-temperature calcination, disassembles the battery and adds it to the furnace, and finally recovers the metal in the form of alloy. Hydrometallurgy mainly uses chemical or biological methods to leaching, purify and separate at a lower temperature. Chemical leaching mainly dissolves the metal elements in the battery through inorganic acids, organic acids or strong alkalis to obtain metal elements with recycling value. Biological leaching mainly uses metabolites produced by microorganisms such as bacteria or fungi to convert insoluble metal elements into soluble metal ion solutions, and then recovers valuable metals in waste LIBs through chemical precipitation or solvent extraction.

[0004] At present, the main bacteria used for bioleaching of waste NMC batteries are: Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Leptospirillum ferriphilum. These acidophilic bacteria are mostly used for bioleaching, while other types of bacteria are rarely used in bioleaching. Most researchers first disassemble the battery, screen out the positive electrode in the LIB as the experimental material, and select bacteria for domestication. The extraction methods used in bioleaching mainly include one-step method, two-step method and waste culture medium method. The one-step method is to add waste LIB powder and microorganisms domesticated to the target solid-liquid ratio into the leaching system at the same time, and bacterial culture / growth and metal extraction occur simultaneously; the two-step method is to culture the microorganisms domesticated to the target solid-liquid ratio to the logarithmic growth period, and then add the waste LIB powder for bioleaching; the waste culture medium method is to culture the microorganisms domesticated to the target solid-liquid ratio to the stable period, filter out the bacteria, and then add the waste LIB powder, and use the culture medium containing the products produced by microbial metabolism for bioleaching.

[0005] Lactobacillus plantarum (L. plantarum) is a facultative anaerobic bacterium and a type of lactic acid bacteria. It mainly produces lactic acid and is used in the food industry such as meat and plant food fermentation, water purification, etc. There are currently no reports on its use in bioleaching NMC batteries.

[0006] The direct recycling method currently used in LIB recycling has high requirements for battery pretreatment and is still in the exploratory stage and has not been applied on a large scale in commercial applications. The application of pyrometallurgical methods is limited by disadvantages such as high energy consumption, easy generation of toxic gases and high requirements for recycling equipment. The use of chemical leaching in hydrometallurgical methods will produce a certain amount of strong acid or strong alkaline waste liquid, which will cause secondary pollution to the environment. In addition, the operation steps are numerous and the economic benefits are not high.

[0007] At present, the acidophilic bacteria commonly used in bioleaching are most suitable for cultivation at a pH value of about 1-3. During the cultivation process, acidophilic bacteria such as sulfur-oxidizing bacteria will produce biogenic sulfuric acid. Therefore, the acidic waste liquid produced during the leaching process will pollute the environment and cause soil acidification. The leaching time is long, the kinetics are slow, and the secondary reactions during the leaching process will also affect the growth of microorganisms. Therefore, it is necessary to select an efficient and more environmentally friendly strain of bacteria for bioleaching to recover valuable metals in waste NMC batteries. Summary of the invention

[0008] In view of the problems in the prior art, the purpose of the present invention is to use Lactobacillus plantarum, which is harmless to the environment and human body, to extract valuable metals from the positive electrode material of waste NMC batteries, and to provide a method that can promote the leaching effect of Lactobacillus plantarum on waste NMC, thereby improving the strong acid or strong alkaline wastewater generated in the previous hydrometallurgical method, and the economic and environmental problems caused in the leaching process.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0010] The present invention domesticates Lactobacillus plantarum to the target solid-liquid ratio, firstly adopts different leaching methods (one-step method, two-step method and waste culture medium method) under the same solid-liquid ratio conditions to explore the method with better leaching effect; then conducts biological leaching experiments on waste NMC battery powder concentrations with different solid-liquid ratios to explore the effect of waste NMC powder concentration on the leaching effect; finally, extracts extracellular polymers (EPS) of Lactobacillus plantarum, and adds different contents of EPS in the biological leaching experiment to improve the leaching effect. To achieve the above purpose, the technical scheme adopted by the present invention is as follows:

[0011] The invention provides a method for extracting waste LiNi from plant lactobacillus x Mn y Co 1-x-y The method of O2 battery specifically comprises the following steps:

[0012] (1) Preparation of battery powder: After disassembling and discharging the waste NMC battery, separate the positive electrode and cut it into small pieces. Soak the small pieces of positive electrode in an organic solvent to dissolve the binder, dry them and then wash them with distilled water. After washing, dry them again and crush them with a powder grinder. The powder is sieved and the waste NMC powder sieved is used for subsequent leaching.

[0013] (2) Domesticate bacteria: inoculate the bacteria into the culture medium, add the waste NMC powder, and culture it in an incubator. 7 cells / mL for subculture.

[0014] (3) Bioleaching: One-step method, two-step method and spent culture medium method were used for leaching respectively. When one-step method was used, the operation was as follows: inoculate the bacteria domesticated in step (2) into the culture medium to make the initial bacterial concentration be 1×10 6 cells / mL, waste NMC powder was added, marked as 0 h, and cultured statically in an incubator;

[0015] When the two-step method is used, the leaching operation is as follows: the bacteria domesticated in step (2) are inoculated into the culture medium to an initial bacterial concentration of 1×10 6 cells / mL, 16 h after inoculation, waste NMC powder was added, marked as 0 h, and cultured statically in an incubator;

[0016] When the spent culture medium method is used, the leaching operation is as follows: inoculate the culture medium with the bacteria domesticated in step (2) to an initial bacterial concentration of 1×10 6 cells / mL, and after 42 h of inoculation, the mixture was filtered with a sterile filter to obtain a filtrate; waste NMC powder was added to the filtrate, which was marked as 0 h, and the mixture was cultured in an incubator.

[0017] (4) The leaching solution obtained in step (3) is sampled, the pH value is measured after sampling, and the bacterial concentration is calculated using a hemocytometer and ICP-OES is measured.

[0018] Furthermore, the organic solvent in step (1) is N-methylpyrrolidone; the drying temperature is 50-60° C.; and the sieve is a 100-mesh sieve.

[0019] Furthermore, the operation of dissolving the binder in step (1) is: immersing the positive electrode in an organic solvent for 1-3 hours at a immersion temperature of 50-60°C.

[0020] Furthermore, the bacteria in step (2) is Lactobacillus plantarum; the initial cell density is 10 6 cells / mL; the initial waste NMC powder concentration was 1.0 g / L; and the culture temperature was 35-37°C.

[0021] Furthermore, the culture medium described in step (2) is MRS culture medium, the components of which are: peptone 10.0 g / L, beef extract powder 5.0 g / L, yeast extract powder 4.0 g / L, glucose 20.0 g / L, KH2PO4 2.0 g / L, diammonium hydrogen citrate 2.0 g / L, CH3COONa 5.0 g / L, MgSO4 0.2 g / L, MnSO4 0.05 g / L, Tween-80 1.0 g / L.

[0022] Furthermore, the subculture operation described in step (2) is as follows: take 2 mL of cultured bacteria, add them to 50 mL of culture medium, then add 50 mg of waste NMC powder, and culture until the number of cells reaches 10 7 The next subculture was carried out when the concentration of spent NMC powder reached cells / mL; the same spent NMC powder concentration was subcultured twice, and the spent NMC powder concentration was increased by 0.5 g / L every two subsequent times; and so on, until the spent NMC powder concentration reached 10.0 g / L.

[0023] Furthermore, the culture time in step (3) is 0.25-7 days, the culture temperature is 35-37°C, and the concentration of waste NMC powder is 3.0 g / L, 5.0 g / L, and 10.0 g / L.

[0024] Furthermore, the bioleaching operation in step (3) further includes adding extracellular polymers (EPS) of Lactobacillus plantarum (L. plantarum), wherein the amount of EPS added is 50-100 mg / L;

[0025] Furthermore, the bioleaching operation in step (3) is as follows: using a one-step method, inoculating the culture medium with the domesticated L. plantarum in step (2) to an initial bacterial concentration of 1×10 6 cells / mL, waste NMC powder and EPS were added, marked as 0 h, and cultured statically in an incubator.

[0026] Furthermore, the EPS preparation method is: L. plantarum is inoculated into MRS medium, and the EPS is extracted after being cultured in a 37°C constant temperature incubator on a shaking platform for 3 days; the specific extraction steps are as follows:

[0027] 1) Divide the liquid culture medium containing bacteria into centrifuge tubes and centrifuge them at 10,000 rpm at 4°C for 20 min to obtain EPS supernatant.

[0028] 2) Filter the EPS supernatant three times with a 0.2 μm sterile filter membrane to remove bacteria and impurities.

[0029] 3) Add three times the volume of 99.9% methanol solution to the filtered EPS supernatant, mix well and place in a 4°C refrigerator overnight to allow precipitation.

[0030] 4) The mixed solution was divided into centrifuge tubes, and centrifuged at 10,000 rpm and room temperature for 10 min, and then the collected precipitates were freeze-dried to obtain the extracellular polymer (EPS) of the Lactobacillus plantarum (L. plantarum).

[0031] The present invention proposes a relatively environmentally friendly method for improving the leaching effect of waste NMC batteries using Lactobacillus plantarum. After Lactobacillus plantarum is domesticated to the target solid-liquid ratio, valuable metals are extracted under different leaching methods and leaching solid-liquid ratios, and the best leaching method is explored as a one-step method. On this basis, different contents of EPS are added, and it is found that the addition of 100 mg / L EPS improves the leaching effect of valuable metals in NMC batteries. The pH value during the extraction process is about 4, which is relatively mild. Lactobacillus plantarum metabolism can produce organic acids such as lactic acid, etc., and no strong acidic wastewater is produced, which reduces pollution to the environment and has low energy requirements.

[0032] Compared with the existing lithium ion battery recycling method technology, the present invention has the following beneficial effects:

[0033] 1) Creatively apply Lactobacillus plantarum in bioleaching. Compared with the current bioleaching methods, Lactobacillus plantarum does not produce strongly acidic wastewater. Compared with chemical leaching and pyrometallurgy, it does not require high energy consumption, nor does it use inorganic acids, organic acids or alkalis. The pH value is milder than that of previous bioleaching, reducing pollution to the environment. At the same time, it has a better extraction effect on valuable metals in waste NMC positive electrode materials.

[0034] 2) In the bioleaching process of Lactobacillus plantarum using different leaching methods at a solid-liquid ratio of 5.0 g / L, it was found that the leaching effect of the one-step method was relatively good. After 7 days, the highest extraction percentages of lithium, nickel, cobalt, and manganese in the one-step method could reach 54.5%, 46.1%, 45.1%, and 45.5%.

[0035] 3) The bioleaching process of Lactobacillus plantarum under different solid-liquid ratios showed that the leaching effect was relatively good when the solid-liquid ratio was 3.0 g / L. After 7 days, the highest extraction percentages of lithium, nickel, cobalt and manganese in the one-step method could reach 62.7%, 53.8%, 52.7% and 54.2% respectively.

[0036] 4) By adding EPS: extracellular polymers of Lactobacillus plantarum for bioleaching, when the solid-liquid ratio was 5.0 g / L, it was found that after adding 100 mg / L EPS, the leaching percentage of lithium ions increased by 8.2%, the leaching percentage of nickel ions increased by 14.6%, the leaching percentage of cobalt ions increased by 7.9%, and the leaching percentage of manganese ions increased by 11.3%, which promoted the extraction of valuable metals in waste NMC batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The invention provides a method for improving the leaching of waste LiNi by plant lactobacillus x Mn y Co 1-x-y Method flow chart of O2 battery effect. DETAILED DESCRIPTION

[0038] Follow the steps below Figure 1 The process shown in the embodiment further illustrates the scheme in the present invention through the embodiment, and the embodiment is not intended to limit the present invention. Unless otherwise specified, the experimental operations in the embodiment are all based on the mature existing technologies in the biological field or the chemical field, and the raw materials and reagents used can be obtained commercially.

[0039] The composition of the MRS culture medium described in the present embodiment is:

[0040] Peptone 10.0 g / L, beef extract powder 5.0 g / L, yeast extract powder 4.0 g / L, glucose 20.0 g / L, KH2PO4 2.0 g / L, diammonium hydrogen citrate 2.0 g / L, CH3COONa 5.0 g / L, MgSO4 0.2 g / L, MnSO4 0.05g / L, Tween-80 1.0 g / L.

[0041] Example 1: Preparation of battery powder

[0042] Used NMC batteries were purchased from a scrap recycling station. After the metal shell was cut open with an angle grinder and disassembled into individual batteries, they were discharged in a 20% NaCl solution for 24 h and further disassembled after being dried in a 55°C oven. First, the shell and the plastic separator inside were peeled off, leaving the positive electrode. The positive electrode was then cut into small pieces and soaked in an N-methylpyrrolidone solution to dissolve the positive electrode binder (polyvinylidene fluoride). After dissolving it in a 60°C oven for 2 h, the dissolved NMC powder was washed three times with distilled water, dried in a 60°C oven, and ground with a powder grinder. The powder was then passed through a 100-mesh sieve, and the powder with a particle size of less than 150 μm was collected for subsequent experiments. The obtained waste battery positive electrode powder was digested using a chemical digestion method (HCl:HNO3=3:1), and the lithium ion content in the solution was determined by inductively coupled plasma optical emission spectrometry (ICP-OES) to be 49.3 mg / g, the nickel ion content to be 172.3 mg / g, the cobalt ion content to be 145.6 mg / g, and the manganese ion content to be 131.8 mg / g.

[0043] Example 2: Domestication of bacteria

[0044] Lactobacillus plantarum was cultured in a 37°C incubator. Waste NMC powder (0.05 g) was added to 50 mL of MRS medium to maintain an initial cell density of 10 6 cells / mL. When the number of cells is 10 7 cells / mL and reached stability, then subcultured; 2 mL of subcultured bacteria was added to 50 mL of MRS medium, and then waste NMC powder (0.05 g) was added. When the number of cells reached 10 7 cells / mL and reached stability. Subculture was performed; the same concentration was subcultured twice, and the concentration of spent MNC powder was increased by 0.5 g / L every two subsequent times; and so on, until the powder concentration reached 10.0 g / L.

[0045] Example 3: Experimental study of different leaching methods

[0046] One-step method: Inoculate L. plantarum in 200 mL MRS medium to an initial bacterial concentration of 1 × 10 6 cells / mL, waste NMC powder (1.0 g) was added to make the final concentration of 5.0 g / L, and 0 h was recorded to start the leaching experiment. The leaching experiment was started at 37°C incubator and cultured at different time intervals: 0.25, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 4.0, 5.0, 6.0, and 7.0 days. The pH value was measured after sampling, and the bacterial concentration was calculated using a hemocytometer. The samples were filtered with a water filter (0.22 μm) and finally placed in a refrigerator at 4°C for standby use. ICP-OES was measured uniformly. The concentrations of lithium, nickel, cobalt, and manganese in the leachate were measured by ICP-OES method and the extraction percentages were calculated: the maximum extraction percentages of lithium, nickel, cobalt, and manganese could reach 54.5%, 46.1%, 45.1%, and 45.5%, respectively.

[0047] Two-step method: Inoculate L. plantarum in 200 mL MRS medium to an initial bacterial concentration of 1 × 10 6 cells / mL, 16 h after inoculation, the pH was measured to be 4.58, 4.57, and 4.54 (three parallel samples), and the bacterial concentration was: 7.4×10 8 cells / mL、8.1×10 8 cells / mL、7.9×10 8 cells / mL, which is in the logarithmic growth phase. Waste NMC powder (1.0 g) was added to make the final concentration of 5.0 g / L, recorded as 0 h, and the leaching experiment began. The leaching experiment was started by static culture in a 37°C incubator, and samples were taken at the same time interval as the one-step method. The pH value was measured after sampling, and the bacterial concentration was calculated using a hemocytometer. The samples were filtered with a water filter (0.22 μm) and finally placed in a refrigerator at 4°C for standby use. ICP–OES was measured uniformly. The concentrations of lithium, nickel, cobalt, and manganese in the leachate were measured by ICP–OES method and the extraction percentages were calculated: the maximum extraction percentages of lithium, nickel, cobalt, and manganese could reach 42.1%, 36.8%, 35.4%, and 37.5%, respectively.

[0048] Spent medium method: Inoculate L. plantarum in 200 mL MRS medium to an initial bacterial concentration of 1 × 10 6 cells / mL, 42 h after inoculation, the pH was measured to be 4.03, 4.00, and 4.01, and the bacterial concentration was: 1.15×10 9 cells / mL、9.4×10 8 cells / mL, 1.11×10 9cells / mL, in the stable period, filtered with a 0.22 μm sterile filter to obtain a filtrate. Waste NMC powder (1.0 g) was added to the filtrate to make a final concentration of 5.0 g / L, recorded as 0 h, and the leaching experiment began. Incubate in a 37°C incubator, take samples at the same time interval as the one-step method, measure the pH value after sampling, filter the samples with a water filter (0.22 μm), and finally place them in a refrigerator at 4°C for standby use, and measure ICP–OES uniformly. The concentrations of lithium, nickel, cobalt, and manganese in the leachate were measured by ICP–OES method and the extraction percentages were calculated: the maximum extraction percentages of lithium, nickel, cobalt, and manganese can reach 45.0%, 37.9%, 34.2%, and 36.0%, respectively.

[0049] Example 4: Experimental study of different solid-liquid ratios

[0050] Inoculate L. plantarum in 200 mL of MRS medium to an initial bacterial concentration of 1 × 10 6 cells / mL, and waste NMC powder (0.6 g, 1.0 g, 2.0 g) was added to make the final concentrations of 3.0 g / L, 5.0 g / L, and 10.0 g / L, respectively. 0 h was marked as the beginning of the leaching experiment. The samples were statically cultured in a 37°C incubator, and samples were taken at the same time intervals as the one-step method. The pH value was measured after sampling, the bacterial concentration was calculated using a hemocytometer, and the samples were filtered with a water filter (0.22 μm). Finally, they were placed in a 4°C refrigerator for standby use and ICP-OES was measured uniformly. The concentrations of lithium, nickel, cobalt, and manganese in the leachate were measured by ICP-OES method and the extraction percentages were calculated: the maximum extraction percentages of lithium, nickel, cobalt, and manganese in the 3.0 g / L leaching process could reach 62.7%, 53.8%, 52.7%, and 54.2%; the maximum extraction percentages of lithium, nickel, cobalt, and manganese in the 5.0 g / L leaching process could reach 54.5%, 46.1%, 45.1%, and 45.5%; the maximum extraction percentages of lithium, nickel, cobalt, and manganese in the 10.0 g / L leaching process could reach 20.9%, 19.4%, 17.4%, and 17.6%.

[0051] Example 5: Experimental study on the effect of adding EPS at different concentrations

[0052] 1. Preparation of EPS

[0053] L. plantarum was inoculated into 3 L MRS medium and cultured in a 37°C constant temperature incubator with a shaker for 3 days. The specific extraction steps are as follows: (1) The liquid culture medium containing bacteria was divided into centrifuge tubes and centrifuged at 10,000 rpm in a 4°C refrigerated centrifuge for 20 min to obtain EPS supernatant. (2) The EPS supernatant was filtered three times with a 0.2 μm sterile filter membrane to remove bacteria and impurities. (3) After filtration, three times the volume of 99.9% methanol solution was added to the EPS supernatant, mixed and placed in a 4°C refrigerator overnight for precipitation. (4) The mixed solution was divided into centrifuge tubes and centrifuged at 10,000 rpm and room temperature for 10 min, and the collected precipitate was freeze-dried for later use.

[0054] 2. Addition of EPS

[0055] Inoculate L. plantarum in 200 mL of MRS medium to an initial bacterial concentration of 1 × 10 6 cells / mL, and waste NMC powder (1.0 g) was added to make the waste NMC powder concentration of 5.0 g / L. Different concentrations of EPS were added: 50 mg / L and 100 mg / L, respectively. The leaching experiment was started at 0 h. The cells were cultured in a 37°C incubator and samples were taken at the same time interval as the one-step method. After sampling, the pH value was measured, the bacterial concentration was calculated using a hemocytometer, the sample was filtered with a water filter (0.22 μm), and finally placed in a refrigerator at 4°C for standby use. ICP–OES was measured uniformly. The concentrations of lithium, nickel, cobalt, and manganese in the leachate were measured by ICP–OES method and the extraction percentages were calculated: the maximum extraction percentages of lithium, nickel, cobalt, and manganese in the leaching process of adding 50 mg / L EPS can reach 51.9%, 48.3%, 41.7%, and 43.8%; the maximum extraction percentages of lithium, nickel, cobalt, and manganese in the leaching process of adding 100 mg / L EPS can reach 62.7%, 60.7%, 53.0%, and 56.8%.

[0056] When the solid-liquid ratio was 5.0 g / L, it was found that after adding 100 mg / L EPS, the leaching percentage of lithium ions increased by 8.2%, the leaching percentage of nickel ions increased by 14.6%, the leaching percentage of cobalt ions increased by 7.9%, and the leaching percentage of manganese ions increased by 11.3%.

Claims

1. Lactobacillus plantarum extracts waste LiNi x Mn y Co 1-x-y O2 battery method, characterized in that, The specific steps include: (1) Preparation of battery powder: After disassembling and discharging the waste NMC battery, separate the positive electrode and cut it into small pieces. Soak the small pieces of positive electrode in an organic solvent to dissolve the binder, dry them and then wash them with distilled water. After washing, dry them again and crush them with a powder grinder. The powder is passed through a sieve and the waste NMC powder screened out is used for subsequent leaching. (2) Domesticate bacteria: inoculate the bacteria into the culture medium, add the waste NMC powder, and culture it in an incubator. When the number of cells reaches 10 7 Cells / mL were used for subculture; (3) Bioleaching: One-step method, two-step method and spent culture medium method were used for leaching; (4) Sampling the leaching solution obtained in step (3), measuring the pH value after sampling, calculating the bacterial concentration using a hemocytometer, and measuring ICP-OES; Wherein, the bioleaching operation described in step (3) further includes adding extracellular polymers of Lactobacillus plantarum.

2. Lactobacillus plantarum leaching waste LiNi according to claim 1 x Mn y Co 1-x-y O2 battery method, characterized in that, The organic solvent described in step (1) is N-methylpyrrolidone; the drying temperature is 50-60°C; the screen is a 100-mesh screen; the operation of dissolving the binder is: immersing the positive electrode in the organic solvent for 1-3 hours at a immersion temperature of 50-60°C.

3. Lactobacillus plantarum leaching waste LiNi according to claim 1 x Mn y Co 1-x-y O2 battery method, characterized in that, The bacteria described in step (2) is Lactobacillus plantarum; the initial cell density is 10 6 cells / mL; the initial waste NMC powder concentration was 1.0 g / L; and the culture temperature was 35-37°C.

4. Lactobacillus plantarum leaching waste LiNi according to claim 1 x Mn y Co 1-x-y O2 battery method, characterized in that, The culture medium described in step (2) is MRS culture medium, which comprises: peptone 10.0 g / L, beef extract powder 5.0 g / L, yeast extract powder 4.0 g / L, glucose 20.0 g / L, KH2PO4 2.0 g / L, diammonium hydrogen citrate 2.0 g / L, CH3COONa5.0 g / L, MgSO4 0.2 g / L, MnSO4 0.05 g / L, Tween-80 1.0 g / L.

5. Lactobacillus plantarum leaching waste LiNi according to claim 4 x Mn y Co 1-x-y O2 battery method, characterized in that, The subculture operation in step (2) is as follows: take 2 mL of cultured bacteria, add them to 50 mL of the culture medium described in claim 4, then add 50 mg of waste NMC powder, and culture until the number of cells reaches 10 7 The next subculture was carried out when the concentration of spent NMC powder reached cells / mL; the same spent NMC powder concentration was subcultured twice, and the spent NMC powder concentration was increased by 0.5 g / L every two subsequent times; and so on, until the spent NMC powder concentration reached 10.0 g / L.

6. Lactobacillus plantarum leaching waste LiNi according to claim 1 x Mn y Co 1-x-y O2 battery method, characterized in that, In the bioleaching described in step (3), when the one-step method is adopted, the operation is as follows: inoculate the bacteria domesticated in step (2) into the culture medium so that the initial bacterial concentration is 1×10 6 cells / mL, waste NMC powder was added, marked as 0 h, and cultured statically in an incubator; When the two-step method is used, the leaching operation is as follows: the bacteria domesticated in step (2) are inoculated into the culture medium to an initial bacterial concentration of 1×10 6 cells / mL, 16 h after inoculation, waste NMC powder was added, which was recorded as 0 h, and cultured statically in an incubator; When the spent culture medium method is used, the leaching operation is as follows: inoculate the culture medium with the bacteria domesticated in step (2) to an initial bacterial concentration of 1×10 6 cells / mL, and after 42 h of inoculation, the mixture was filtered with a sterile filter to obtain a filtrate; waste NMC powder was added to the filtrate, which was marked as 0 h, and the mixture was cultured in an incubator.

7. Lactobacillus plantarum leaching waste LiNi according to claim 6 x Mn y Co 1-x-y O2 battery method, characterized in that, The culture time in step (3) is 0.25-7 days, the culture temperature is 35-37°C, and the concentration of waste NMC powder is 3.0 g / L, 5.0 g / L, and 10.0 g / L.

8. Lactobacillus plantarum leaching waste LiNi according to claim 1 x Mn y Co 1-x-y O2 battery method, characterized in that, The added amount of the extracellular polymer of Lactobacillus plantarum is 50-100 mg / L.

9. Lactobacillus plantarum leaching waste LiNi according to claim 1 x Mn y Co 1-x-y O2 battery method, characterized in that, The bioleaching operation in step (3) is: a one-step method; the specific operation is: inoculating the plant lactobacillus tamed in step (2) into the culture medium to make the initial bacterial concentration be 1×10 6 cells / mL, added waste NMC powder and extracellular polymers of Lactobacillus plantarum, marked as 0 h, and cultured statically in an incubator.

10. Leaching waste LiNi by Lactobacillus plantarum according to claim 1 x Mn y Co 1-x-y O2 battery method, characterized in that, The preparation method of the extracellular polymer of Lactobacillus plantarum is as follows: Lactobacillus plantarum is inoculated into MRS culture medium, and the culture is carried out in a shaking incubator at 37°C for 3 days before extraction; the specific extraction steps are as follows: 1) Dispense the liquid culture medium containing bacteria into centrifuge tubes and centrifuge at 10,000 rpm at 4°C for 20 min to obtain EPS supernatant; 2) Filter the EPS supernatant three times with a 0.2 μm sterile filter membrane to remove bacteria and impurities; 3) Add three times the volume of 99.9% methanol solution to the filtered EPS supernatant, mix well and place in a 4°C refrigerator overnight to allow precipitation; 4) The mixed solution was divided into centrifuge tubes, and centrifuged at 10,000 rpm and room temperature for 10 min. The collected precipitates were freeze-dried to obtain the extracellular polymers of Lactobacillus plantarum.

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