Method for leaching positive electrode powder of waste lithium battery in neutral environment by utilizing common desulfurization vibrio

Abstract

The invention discloses a method for leaching anode powder of a waste lithium battery in a neutral environment by utilizing common desulfurization vibrio, and belongs to the technical field of waste battery metal resource recovery treatment and biological metallurgy. The method comprises the following steps: inoculating common desulfurization vibrio obtained through gradient domestication into an improved culture medium, then activating a bacterial liquid, and constructing a biological leaching system, so that the biological leaching of valuable metals in waste NCM, NCA, LFP, LCO, LMO and other positive electrode materials is realized. According to the method, common desulfurization vibrio is creatively adopted as a leaching strain, the dependence of traditional biological leaching on acidophilic bacteria is abandoned, efficient dissolution and directional separation of valuable metals in various waste LIBs positive electrode materials are achieved under the mild neutral condition, and a brand-new microbial technical scheme is provided for waste LIBs positive electrode valuable metal recovery.

Description

Technical Field

[0001] This invention belongs to the field of waste battery metal resource recycling and biometallurgical technology, specifically involving a method for leaching waste lithium battery cathode powder using common desulfurizing Vibrio bacteria in a neutral environment. Background Technology

[0002] Lithium-ion batteries (LIBs), with their core advantages such as high energy density and long cycle life, have become a key competitive arena in the global new energy industry. Their applications have expanded from new energy vehicles and consumer electronics to emerging and diverse fields such as energy storage power stations, electric ships, and low-altitude aircraft. Currently, mainstream LIBs include lithium nickel cobalt manganese oxide batteries (NCM), lithium nickel cobalt aluminum oxide batteries (NCA), lithium iron phosphate batteries (LFP), lithium cobalt oxide batteries (LCO), and lithium manganese oxide batteries (LMO). Given that the average service life of LIBs is typically only 5-8 years, the production of used LIBs is experiencing explosive growth as early-stage LIBs reach retirement standards. Lithium-ion batteries (LIBs) are mainly composed of positive electrode materials, negative electrode materials, electrolytes, separators, current collectors, and shells. They are rich in valuable metals such as lithium, cobalt, nickel, and manganese, but also contain toxic substances with environmental risks, such as organic solvents and fluorides. If waste LIBs are not properly disposed of in a timely manner, it will not only waste metal resources but also pollute soil and water bodies due to the leakage of toxic and hazardous substances. Therefore, developing efficient recycling technologies for waste LIBs and realizing their high-value resource utilization has become a critical issue that urgently needs to be addressed for the sustainable development of the new energy industry.

[0003] Existing recycling methods mainly include direct regeneration, pyrometallurgy, and hydrometallurgy. Direct regeneration suffers from problems such as high raw material requirements, low consistency of recycled materials, and insufficient adaptability for large-scale applications, resulting in numerous constraints on process application (Ren et al., 2024; Shen et al., 2024). Pyrometallurgy has high energy consumption and large carbon emissions (Cornelio et al., 2024). Hydrometallurgy includes chemical leaching and bioleaching. The former requires the use of large amounts of chemical reagents and easily generates strong acid or strong alkaline wastewater, which can lead to equipment corrosion (Soltanizadeh et al., 2025). Biohydrometallurgy, also known as bioleaching, has attracted much attention in recent years due to its environmental friendliness and mild reaction. However, existing bioleaching technologies mostly rely on highly acidophilic bacteria (such as *Thiobacillus ferrooxidans*, *Thiobacillus thiooxidans*, and *Leptospira*), whose metabolic acid production can cause the system pH to drop to 1.0-2.5, making it impossible to avoid the generation of highly acidic wastewater and the risk of equipment corrosion. Although some studies have attempted to use heterotrophic bacteria that produce organic acids, such as lactic acid bacteria (Xia et al., 2025), the pH of these systems remains weakly acidic, ranging from 4.0 to 5.0, requiring wastewater to be neutralized before discharge, thus increasing overall costs. Current research reports that dissimilar metal-reducing bacteria such as Shewanella can leach valuable metals from waste LIBs under neutral conditions (pH 7.0-8.1) (Kim et al., 2024; Li et al., 2025). However, these strains typically dissolve large amounts of manganese, cobalt, nickel, and lithium simultaneously from the cathode material through a reductive dissolution mechanism, resulting in a complex composition of metal ions in the leachate. This significantly increases the difficulty and cost of subsequent lithium resource separation and purification processes. Therefore, developing a novel microbial system capable of "preferential lithium extraction" or exhibiting specific metal selectivity during the leaching stage is crucial for simplifying the recycling process and reducing separation costs.

[0004] Sulfate-reducing bacteria, as a unique type of anaerobic microorganism, not only possess extracellular electron transfer capabilities, but their unique sulfur cycle metabolic mechanism (Jorge et al., 1991) may interact uniquely with waste LIB cathode materials, providing a novel biological pathway to solve the aforementioned selective leaching problem. As a typical representative and model strain of sulfate-reducing bacteria, *Vibrio desulfurans* has significant advantages such as rapid growth rate, extensive culture conditions, and strong environmental adaptability. During metabolism, this strain not only secretes various organic acids such as acetic acid and succinic acid, as well as extracellular polymers with complexing functions, but also possesses highly efficient extracellular electron transfer capabilities. More importantly, the sulfides produced by this strain can undergo in-situ precipitation reactions with dissolved transition metals (such as nickel, cobalt, and manganese). Theoretically, this could disrupt the crystal structure of waste LIB cathode materials, releasing metals while inhibiting non-target metals from entering the solution, thus providing a natural biochemical basis for the preferential selective recovery of lithium. Furthermore, through long-term environmental evolution, *Vibrio desulfurans* has developed a unique tolerance mechanism to high concentrations of metal ions, maintaining stable metabolic activity even in complex waste LIB systems (Goulhen et al., 2006; Jeong et al., 2015). However, no research has yet been reported on the utilization of *Vibrio desulfurans* in the resource recovery of waste LIBs.

[0005] In summary, bioleaching using common desulfurizing Vibrio bacteria theoretically provides a novel technological pathway for the resource recovery of various LIBs cathode materials, including waste NCM, NCA, LFP, LCO, and LMO. This approach is expected to overcome the environmental pollution drawbacks of traditional acidophilic bacteria by utilizing its unique "neutral anaerobic" and "sulfide precipitation" mechanisms, while also addressing the challenges of poor leaching selectivity and subsequent separation difficulties associated with existing neutral strains (such as Shewanella). However, current research on the application of common desulfurizing Vibrio bacteria in the recycling of waste LIBs is still lacking both domestically and internationally. Constructing an efficient sulfate-reducing bacterial leaching system and elucidating its leaching patterns for different waste LIBs cathode materials are pressing technical problems that need to be solved in the field of biometallurgy. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention aims to provide a method for leaching cathode powder from spent lithium-ion batteries (LIBs) using common desulfurizing Vibrio bacteria under a neutral anaerobic environment. This invention overcomes the acidity limitations of traditional biometallurgy, utilizing the unique metabolic diversity and extracellular electron transfer capabilities of this strain to achieve efficient leaching and targeted separation of valuable metals from various spent LIB cathode materials (such as NCM, NCA, and LFP) under mild neutral conditions. This provides a novel microbial technology solution for the green and low-carbon resource utilization of spent LIBs.

[0007] The technical solution provided by this invention:

[0008] A method for leaching spent lithium battery cathode powder using common desulfurizing Vibrio bacteria under a neutral environment includes the following steps: The domesticated Vibrio desulfurization bacteria were inoculated into a modified culture medium at a volume ratio of 5%-10% and cultured at 30℃ under strict anaerobic conditions to obtain activated Vibrio desulfurization bacterial solution. Waste LIBs positive electrode powder was added to the modified culture medium for Vibrio desulfurization, followed by the activated Vibrio desulfurization bacterial solution to construct a bioleaching system. The system was sealed and placed in a 30℃ constant temperature and 60% relative humidity incubator for static culture over a 7-day leaching period, with samples taken every day. The pH and bacterial concentration of the system were measured simultaneously during sampling. The extracted liquid samples were filtered through a 0.22μm aqueous microporous membrane, and the metal ion concentration in the filtrate was detected using inductively coupled plasma atomic emission spectrometry (ICP-AES), and the leaching percentage of each metal element was calculated accordingly. The domestication process of the domesticated Vibrio desulfurization bacteria was as follows: waste LIBs positive electrode powder was added to the modified culture medium, controlling the initial solid-liquid ratio at 0.25 g / L, and the initial bacterial concentration was ~10... 7 Inoculate with common desulfurized Vibrio at an inoculum size of cells / mL and incubate at 30°C under strictly anaerobic conditions; monitor bacterial growth regularly, and continue incubation until the bacterial concentration reaches ~10⁶ cells / mL. 8 When the cells / mL (logarithmic growth phase) is reached, the first round of adaptive culture is completed, and the bacterial solution of the first round of culture is obtained; the domestication is carried out by the gradient increment method to obtain the domesticated Vibrio desulfurization strain.

[0009] Furthermore, the preparation method of the waste LIBs positive electrode powder is as follows: disassemble the waste LIBs, dissolve the positive electrode binder polyvinylidene fluoride (PVDF) with N-methylpyrrolidone (NMP), remove the separator and negative electrode, peel off the positive electrode material and aluminum foil current collector, crush and grind, and pass through a 100-mesh sieve to obtain LIBs powder for bioleaching.

[0010] Furthermore, the modified culture medium comprises: sodium sulfate 4.2 g / L, sodium bicarbonate 1.8 g / L, sodium carbonate 0.4 g / L, concentrated salt mixture 10.0 mL / L, mineral concentrate 10.0 mL / L, vitamin mixture 15.0 mL / L, 0.4% calcium chloride monohydrate 10.0 mL / L, 1.0% magnesium sulfate heptahydrate 10.0 mL / L, 1 mM selenium-tungsten solution 87.6 mL / L, and 60 mM sodium lactate 8.4 mL / L.

[0011] Furthermore, when constructing the bioleaching system, the solid-liquid ratio of the system was controlled at 1.0 g / L-2.0 g / L; the sampling operation was carried out in an anaerobic workstation equipped with anaerobic indicators throughout the process, and the oxygen concentration in the workstation was monitored in real time to ensure that the oxygen concentration remained stable below 100 ppm throughout the process; in the detection process, the bacterial concentration in the system was quantitatively analyzed by hemocytometer counting method, and the pH value of the system was measured by a precision pH meter with an accuracy of ±0.01.

[0012] Furthermore, the leaching percentage of metal elements is calculated as follows: Metal leaching percentage = Metal ion concentration in filtrate × Filtrate volume / Total metal content in waste LIBs cathode powder × 100%.

[0013] Furthermore, the enrichment and cryopreservation method for common desulfurization Vibrio is as follows: Take the acclimated bacterial culture in the logarithmic growth phase, inoculate it into a fresh modified culture medium free of waste LIBs positive electrode powder, and carry out enrichment culture to remove residual mineral particles and increase the bacterial count; wait until the bacterial concentration reaches ~2×10⁻⁶. 8 When the bacterial culture reaches 100 cells / mL, transfer the culture to an anaerobic workstation. Under a strictly anaerobic environment, mix the bacterial culture with 10% (v / v) dimethyl sulfoxide (DMSO) sterile cryopreservation solution at a volume ratio of 9:1 to achieve a final DMSO concentration of 1%. Then, dispense the mixture into anaerobic cryopreservation tubes, 1-2 mL per tube, tighten the caps, seal with sealing film, and immediately store in a -80°C freezer.

[0014] Furthermore, the method for acclimatization using the gradient acclimatization method is as follows: The bacterial culture from the first round of culture is taken and transferred to fresh modified culture medium at the same inoculation amount, increasing the solid-liquid ratio to 0.5 g / L, and cultured under the same conditions until the bacterial concentration reaches ~10⁻⁶ again. 8 cells / mL; and so on, the solid-liquid ratio was increased by 0.25 g / L in each round of transfer culture; after ~20 days of continuous gradient acclimatization, ordinary desulfurization Vibrio bacteria that could adapt to the environment of high concentration of waste LIBs positive electrode powder were obtained.

[0015] Further, the concentrated salt mixture comprises: potassium dihydrogen phosphate 42.0 g / L, dipotassium hydrogen phosphate 22.0 g / L, ammonium chloride 20.0 g / L, and potassium chloride 38.0 g / L; the concentrated mineral solution comprises: magnesium sulfate 3.0 g / L, manganese sulfate monohydrate 3.0 g / L, sodium chloride 3.0 g / L, ferrous sulfate heptahydrate 0.1 g / L, zinc chloride 0.1 g / L, cobalt chloride hexahydrate 0.1 g / L, and calcium chloride dihydrate 0.1 g / L; the vitamin mixture comprises... The components are: biotin 0.002 g / L, pantothenic acid 0.005 g / L, cobalamin 0.0001 g / L, para-aminobenzoic acid 0.005 g / L, lipoic acid 0.005 g / L, niacin 0.005 g / L, thiamine 0.005 g / L, riboflavin 0.005 g / L, pyridoxine hydrochloride 0.01 g / L, and folic acid 0.002 g / L; the components of the selenium-tungsten solution are: sodium hydroxide 0.5 g / L, sodium selenate pentahydrate 3 mg / L, and sodium tungstate dihydrate 4 mg / L.

[0016] Furthermore, after the modified culture medium is prepared, it is degassed by high-purity nitrogen gas with a purity of ≥99.99% for 2 hours, then sealed and sterilized at high temperature to create a strictly anaerobic environment.

[0017] The acclimatization process follows a "gradual increase" principle, with each acclimatization cycle increasing the solid-liquid ratio by only 0.25 g / L while keeping all other conditions constant. A strictly anaerobic environment must be maintained throughout the process. Common desulfurization vibrio is extremely sensitive to oxygen; even a small amount of oxygen leakage can lead to decreased bacterial activity or death, resulting in acclimatization failure. Regarding strain preservation, DMSO has poor thermal stability and will decompose under conventional high-pressure steam sterilization conditions (121℃, 0.1 MPa, 20 min), producing toxic byproducts such as dimethyl sulfide and formaldehyde. Therefore, a 0.22 μm aqueous microporous membrane is used for filtration sterilization. The bacterial culture is mixed with 10% (v / v) DMSO cryopreservation solution at a 9:1 volume ratio. The ratio must be strictly controlled to ensure a final DMSO concentration of 1%. Too high a concentration will cause cytotoxicity, while too low a concentration will not provide effective cryopreservation protection.

[0018] The core technical feature of this invention is that it provides a leaching method for valuable metals in waste LIBs cathode powder under a neutral environment based on common desulfurizing Vibrio. This method has broad applicability and can cover the resource recovery of mainstream waste LIBs cathode powders such as NCM, NCA, LFP, LCO, and LMO. This method abandons the dependence of traditional bioleaching on acidophilic bacteria, utilizing the unique "acidolysis-reduction-precipitation" coupling mechanism of common desulfurizing Vibrio: while promoting metal dissolution through organic acids and extracellular electron transfer, it uses negative divalent sulfur ions generated by metabolism to convert dissolved transition metals such as nickel, cobalt, and manganese into insoluble sulfide precipitates in situ, allowing chemically stable lithium ions to remain in the leachate, thereby achieving "in-situ selective separation" and preferential extraction of lithium resources. This characteristic effectively solves the separation problem caused by multi-metal co-dissolution in traditional leaching processes, and has the technical advantages of outstanding energy efficiency, environmental friendliness, and no secondary pollution.

[0019] Compared with the prior art, the method of the present invention has the following beneficial effects:

[0020] 1. This invention abandons the reliance on acidophilic bacteria in traditional bioleaching and innovatively uses common desulfurizing Vibrio as the leaching strain. This method solves the problem that traditional strains can only work in acidic environments, providing a novel microbial technology solution for the recovery of valuable metals from the cathode of waste LIBs. This invention utilizes the unique sulfur respiration metabolism mechanism of common desulfurizing Vibrio to achieve preferential and selective recovery of lithium resources. The bio-derived divalent sulfur ions produced by this strain during metabolism can react in situ with dissolved transition metals such as nickel, cobalt, and manganese to form insoluble sulfide precipitates, thereby retaining chemically stable lithium ions in the leachate. This "in-situ precipitation-selective leaching" mechanism significantly reduces the content of impurity metals in the leachate and greatly simplifies the subsequent hydrometallurgical separation and purification process for lithium.

[0021] 2. The leaching process of this invention maintains a stable near-neutral pH range of 7.1-7.5 throughout the entire process, eliminating the need for strong acid reagents and preventing the generation of acidic wastewater from the source. This avoids the risk of equipment corrosion and the cost of subsequent wastewater neutralization treatment, significantly reducing environmental pollution hazards and process operation and maintenance costs, and taking into account both environmental friendliness and economic feasibility.

[0022] 3. With its excellent metabolic diversity, extracellular electron transfer ability and metal ion tolerance, common desulfurization vibrio can be adapted to various types of waste LIBs positive electrode systems such as NCM, NCA, LFP, LCO, and LMO, effectively solving the problem of limited adaptability of existing strains. Attached Figure Description

[0023] Figure 1 This is a flowchart of the method for leaching waste LIBs positive electrode powder using common desulfurization Vibrio in a neutral environment according to the present invention. Detailed Implementation

[0024] This invention provides a method for leaching waste LIBs positive electrode powder using common desulfurization Vibrio bacteria in a neutral environment. The waste LIBs include common types such as NCM, NCA, LFP, LCO, and LMO.

[0025] In this embodiment of the invention, the common desulfurized Vibrio JW710 parental strain was obtained from Lawrence Berkeley National Laboratory in California, USA. The parental strain was inoculated into a special culture medium and cultured anaerobicly at 30°C. A bacterial culture was prepared and stored at -80°C in the Microbial Corrosion and Biofouling Research Group of Northeastern University.

[0026] The common desulfuric vibrio JW710 parental strain was inoculated into a modified culture medium and cultured under strictly anaerobic conditions. To ensure the singleness and accuracy of the strain source, the amplified strain was verified by 16S rRNA gene sequencing.

[0027] A method for leaching spent lithium battery cathode powder using common desulfurizing Vibrio bacteria under neutral conditions, such as... Figure 1 As shown, it includes the following steps:

[0028] Step 1: Pre-processing:

[0029] Preparation of waste LIBs positive electrode powder: Disassemble waste LIBs, dissolve the positive electrode binder polyvinylidene fluoride (PVDF) with N-methylpyrrolidone (NMP), remove the separator and negative electrode, peel off the positive electrode material and aluminum foil current collector, crush and grind, and pass through a 100-mesh sieve to obtain LIBs powder for bioleaching.

[0030] The modified culture medium consists of: sodium sulfate 4.2 g / L, sodium bicarbonate 1.8 g / L, sodium carbonate 0.4 g / L, concentrated salt mixture 10.0 mL / L, mineral concentrate 10.0 mL / L, vitamin mixture 15.0 mL / L, 0.4% calcium chloride monohydrate 10.0 mL / L, 1.0% magnesium sulfate heptahydrate 10.0 mL / L, 1 mM selenium-tungsten solution 87.6 mL / L, and 60 mM sodium lactate 8.4 mL / L. After the modified culture medium is prepared, it is purged with high-purity nitrogen gas (≥99.99%) for 2 hours to degas, then sealed and sterilized at high temperature to create a strictly anaerobic environment.

[0031] Step 2: Gradual acclimatization and preservation of strains:

[0032] a. Add spent LIBs positive electrode powder to the modified culture medium, controlling the initial solid-liquid ratio at 0.25 g / L, and adjust the initial bacterial concentration to ~10. 7Inoculate with common desulfurized Vibrio at an inoculum size of cells / mL and incubate at 30°C under strictly anaerobic conditions; monitor bacterial growth regularly, and continue incubation until the bacterial concentration reaches ~10⁶ cells / mL. 8 When the bacterial count reaches 1000 cells / mL (logarithmic growth phase), the first round of adaptation culture is completed, and the first round of culture solution is obtained. The acclimatization is carried out using a gradient acclimatization method to obtain the acclimatized common desulfurized Vibrio bacteria.

[0033] b. Solid-liquid ratio gradient acclimatization:

[0034] The acclimatization process was carried out using a gradient acclimatization method. The bacterial culture from the first round was transferred to fresh modified culture medium at the same inoculum level, increasing the solid-liquid ratio to 0.5 g / L. The culture was then carried out under the same conditions until the bacterial concentration reached ~10⁻⁶ again. 8 cells / mL; and so on, the solid-liquid ratio was increased by 0.25 g / L in each round of transfer culture; after ~20 days of continuous gradient acclimatization, common desulfurization Vibrio bacteria that could adapt to the high concentration of waste LIBs positive electrode powder environment were obtained.

[0035] c. Enrichment and cryopreservation:

[0036] Take the acclimatized bacterial culture in the logarithmic growth phase and inoculate it into fresh modified culture medium free of waste LIBs positive electrode powder. Perform enrichment culture to remove residual mineral particles and expand the bacterial count; wait until the bacterial concentration reaches ~2×10⁻⁶. 8 When the bacterial culture reaches 1000 cells / mL, transfer the culture to the anaerobic workstation. Under a strictly anaerobic environment, mix the bacterial culture with 10% (v / v) dimethyl sulfoxide (DMSO) sterile cryopreservation solution at a volume ratio of 9:1 to make the final concentration of DMSO 1%. Then, dispense the mixture into anaerobic cryopreservation tubes, 1-2 mL per tube, tighten the cap, seal with sealing film, and immediately store in a -80°C freezer.

[0037] Step 3: Leaching of valuable metals from LIBs cathode powder:

[0038] The domesticated *Vibrio desulfurization* strain was inoculated into a modified culture medium at a volume ratio of 5%-10% and cultured at 30°C under strict anaerobic conditions to obtain an activated *Vibrio desulfurization* bacterial solution, thus achieving full activation of the strain. Waste LIBs positive electrode powder was added to the modified *Vibrio desulfurization* culture medium, followed by inoculation with the activated *Vibrio desulfurization* bacterial solution to construct a bioleaching system. The system was sealed and placed in a 30°C, 60% relative humidity incubator for static culture over a 7-day leaching period, with samples taken every day during this period. The pH and bacterial concentration of the system were measured simultaneously during sampling. The extracted liquid samples were filtered through a 0.22μm aqueous microporous membrane and then analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES). ICP-OES is used to detect the concentration of metal ions in the filtrate and calculate the leaching percentage of each metal element. The calculation method for the leaching percentage of metal elements is: metal leaching percentage = metal ion concentration in filtrate × filtrate volume / total metal content in waste LIBs cathode powder × 100%.

[0039] When constructing the bioleaching system, the solid-liquid ratio of the system was controlled at 1.0 g / L-2.0 g / L. The sampling operation was carried out in an anaerobic workstation equipped with anaerobic indicators, and the oxygen concentration in the workstation was monitored in real time to ensure that the oxygen concentration remained stable below 100 ppm throughout the process. In the detection stage, the bacterial concentration in the system was quantitatively analyzed by hemocytometer counting method, and the pH value of the system was measured by a precision pH meter with an accuracy of ±0.01.

[0040] The concentrated salt solution comprises: potassium dihydrogen phosphate 42.0 g / L, dipotassium hydrogen phosphate 22.0 g / L, ammonium chloride 20.0 g / L, and potassium chloride 38.0 g / L; the mineral concentrate comprises: magnesium sulfate 3.0 g / L, manganese sulfate monohydrate 3.0 g / L, sodium chloride 3.0 g / L, ferrous sulfate heptahydrate 0.1 g / L, zinc chloride 0.1 g / L, cobalt chloride hexahydrate 0.1 g / L, and calcium chloride dihydrate 0.1 g / L; the vitamin solution comprises: The components of the seleno-tungsten solution are: biotin 0.002 g / L, pantothenic acid 0.005 g / L, cobalamin 0.0001 g / L, para-aminobenzoic acid 0.005 g / L, lipoic acid 0.005 g / L, niacin 0.005 g / L, thiamine 0.005 g / L, riboflavin 0.005 g / L, pyridoxine hydrochloride 0.01 g / L, and folic acid 0.002 g / L; the components of the seleno-tungsten solution are: sodium hydroxide 0.5 g / L, sodium selenate pentahydrate 3 mg / L, and sodium tungstate dihydrate 4 mg / L.

[0041] The specific components and functions of the four mixed liquids in the modified culture medium are as follows:

[0042] Concentrated salt solution (potassium dihydrogen phosphate 42.0 g / L, dipotassium hydrogen phosphate 22.0 g / L, ammonium chloride 20.0 g / L, potassium chloride 38.0 g / L) provides the strain with basic inorganic nutrients such as phosphorus, nitrogen, and potassium. Simultaneously, phosphate buffering helps maintain the pH stability of the culture medium, and the high concentration of salt ions regulates the osmotic pressure of the system, maintaining cell morphology. Mineral concentrate (magnesium sulfate 3.0 g / L, manganese sulfate monohydrate 3.0 g / L, sodium chloride 3.0 g / L, ferrous sulfate heptahydrate 0.1 g / L, zinc chloride 0.1 g / L, cobalt chloride hexahydrate 0.1 g / L, calcium chloride dihydrate 0.1 g / L) supplements macro- and micro-minerals such as magnesium, iron, and zinc, ensuring enzyme activity activation, cell structure stability, and normal physiological metabolic function. Vitamin mixture (biotin 0.002 g) The solution contains: pantothenic acid 0.005 g / L, cobalamin 0.0001 g / L, para-aminobenzoic acid 0.005 g / L, lipoic acid 0.005 g / L, niacin 0.005 g / L, thiamine 0.005 g / L, riboflavin 0.005 g / L, pyridoxine hydrochloride 0.01 g / L, folic acid 0.002 g / L. These vitamins provide essential vitamins that the strain cannot synthesize or cannot synthesize sufficiently, acting as cofactors or prosthetic groups for enzymes and participating in key physiological processes such as cell metabolism, energy synthesis, and genetic material replication. The selenium-tungsten solution (sodium hydroxide 0.5 g / L, sodium selenate pentahydrate 3 mg / L, sodium tungstate dihydrate 4 mg / L) provides selenium and tungsten, two rare trace elements, to meet the strain's specific metabolic needs. Sodium hydroxide maintains the solution's alkalinity, preventing trace element precipitation and improving its bioavailability.

[0043] Example 1

[0044] A method for leaching spent NCM battery cathode powder using common desulfurizing Vibrio bacteria under neutral conditions, such as... Figure 1 As shown, the specific operation steps are as follows:

[0045] Step 1: Pre-processing:

[0046] The pretreatment process includes the following steps, which are in no particular order: a. Preparation of NCM battery cathode powder, b. Acquisition of common desulfurization Vibrio, c. Preparation of culture medium;

[0047] a. Preparation of NCM battery cathode powder:

[0048] Used NCM622 batteries were completely immersed in a 2 mol / L sodium chloride solution for 24-36 hours until the voltage stabilized at 0-0.5V as measured by a multimeter, eliminating the risk of short circuits and electric shock during subsequent disassembly. The battery casing was then cut open using an insulated cutter, and the individual cells were placed in a forced-air drying oven at 60℃ for 12 hours to remove surface and pore-bound free water. After drying, with the assistance of a protective kit consisting of insulated gloves, insulated pliers, and an insulated workbench, the separator, positive electrode, and negative electrode were separated sequentially. The positive electrode was cut into 2cm × 2cm square pieces and placed in a sealed container containing NMP solution. It was then immersed at 65℃ for 1 hour to dissolve the PVDF binder using NMP, achieving separation of the active material from the aluminum foil current collector. After immersion, the electrode was removed, dried at 60℃ to remove residual NMP, and then immersed in a sodium hydroxide solution with ultrasonic assistance to accelerate aluminum foil peeling. After the aluminum foil is completely removed, the active material is taken out and repeatedly washed with deionized water until the washing solution is neutral to remove residual alkali and impurities. After washing, the positive electrode active material is transferred to a vacuum drying oven and dried to constant weight at 80℃ and -0.1MPa to completely remove crystal water and free water. Finally, the dried active material is coarsely crushed to a particle size ≤5mm by a jaw crusher, and then transferred to a planetary ball mill for fine grinding at a ball-to-material ratio of 10:1, a rotation speed of 500r / min, and a grinding time of 5h. The grinding product is dry-sieved through a 100-mesh sieve, and the undersize material is collected to obtain uniformly dispersed NCM622 positive electrode powder. The powder is packaged in a light-proof sealed container and stored in a dry environment with a relative humidity ≤30% for subsequent bioleaching processes. The obtained NCM622 cathode powder was digested using a chemical digestion method (HNO3:HClO4:HF=2:1:2, v / v / v). The concentration of metal ions in the digestion solution was determined by ICP-OES. The calculated lithium content in the waste NCM622 battery powder was 56.4 mg / g, nickel content was 291.4 mg / g, cobalt content was 98.1 mg / g, and manganese content was 90.7 mg / g.

[0049] b. Obtaining common desulfurization vibrio:

[0050] The parent strain of *Vibrio desulfurans* JW710 was obtained from Lawrence Berkeley National Laboratory, California, USA. This strain was inoculated into a modified culture medium and cultured under strictly anaerobic conditions at 30°C to eliminate contamination by facultative anaerobic bacteria and to prevent bacterial death due to oxygen. The culture was continued until the bacterial concentration reached ~2 × 10⁻⁶. 8 The bacterial strain was prepared at a concentration of cells / mL. After the strain identity was verified by 16S rRNA sequencing, it was stored in a -80℃ freezer by the Microbial Corrosion and Biofouling Research Group of Northeastern University.

[0051] c. Preparation of culture medium:

[0052] The culture medium for common desulfurized Vibrio is an improved formula obtained through multiple rounds of experimental optimization. Its components are: sodium sulfate 4.2 g / L, sodium bicarbonate 1.8 g / L, sodium carbonate 0.4 g / L, concentrated salt mixture 10.0 mL / L, mineral concentrate 10.0 mL / L, vitamin mixture 15.0 mL / L, 0.4% calcium chloride monohydrate 10.0 mL / L, 1.0% magnesium sulfate heptahydrate 10.0 mL / L, 1 mM selenium-tungsten solution 87.6 mL / L, and 60 mM sodium lactate 8.4 mL / L. Four types of mixed solutions in the culture medium work together to support the growth and metabolism of the strain: concentrated salt solution provides basic inorganic nutrients, maintains the pH of the medium, and regulates the osmotic pressure of the system; concentrated mineral solution replenishes macro and micro minerals, ensuring the normal operation of enzyme activity and cellular physiological functions; vitamin solution provides essential vitamins that the strain cannot synthesize or cannot synthesize sufficiently, participating in key processes such as cell metabolism, energy synthesis, and genetic material replication; and selenium-tungsten solution provides rare trace elements to meet the specific metabolic needs of the strain. After the modified culture medium is prepared, it is purged with high-purity nitrogen gas (≥99.99%) for 2 hours for degassing, sealed, and then sterilized at high temperature to ensure the strictly anaerobic environment required for cultivation.

[0053] Step 2: Common desulfurization Vibrio acclimation and preservation via NCM622 gradient:

[0054] a. Add the waste NCM622 positive electrode powder obtained in step 1(a) to the modified culture medium of common desulfurized Vibrio prepared in step 1(c), controlling the initial solid-liquid ratio to be 0.25 g / L. Adjust the initial bacterial concentration to ~10... 7 Inoculate with common desulfurized Vibrio at an inoculum size of cells / mL and incubate at 30°C under strictly anaerobic conditions. Monitor bacterial growth regularly, and continue incubation until the bacterial concentration reaches ~10⁻⁶ cells / mL. 8 The first round of adaptive culture is completed when the number of cells / mL (logarithmic growth phase) reaches 100%.

[0055] b. Solid-liquid ratio gradient acclimatization:

[0056] Acclimation was carried out using a gradient acclimation method. The bacterial culture from the first round was transferred to fresh modified culture medium at the same inoculum size, increasing the solid-liquid ratio to 0.5 g / L. The culture was then incubated under the same conditions until the bacterial concentration reached ~10⁻⁶ again. 8 cells / mL. Similarly, the solid-liquid ratio was increased by 0.25 g / L in each round of transfer culture. After ~20 days of continuous gradient acclimatization, acclimatized bacteria capable of adapting to high concentrations of NCM622 powder were obtained.

[0057] c. Enrichment and cryopreservation:

[0058] Take the acclimatized bacterial culture in the logarithmic growth phase and inoculate it into fresh modified culture medium free of NCM622 cathode powder for enrichment culture to remove residual mineral particles and expand the bacterial count. Wait until the bacterial concentration reaches ~2×10⁻⁶. 8 When the bacterial culture reaches a concentration of cells / mL, transfer the culture to an anaerobic workstation. Under strictly anaerobic conditions, mix the bacterial culture with 10% (v / v) dimethyl sulfoxide (DMSO) sterile cryopreservation solution at a volume ratio of 9:1 (to achieve a final DMSO concentration of 1%). Then, aliquot the mixture into anaerobic cryovials, 1-2 mL per tube, tighten the cap, seal with sealing film, and immediately store at -80°C.

[0059] Step 3: Bioleaching of valuable metals from waste NCM622 cathode material:

[0060] 80 mL of modified culture medium was added to a 100 mL serum bottle. After acclimatization and activation to the logarithmic growth phase, *Vibrio desulfurans* was inoculated into the medium at a 10% v / v inoculum. Waste NCM622 cathode powder was then added to maintain a solid-liquid ratio of 1.0 g / L. The serum bottle was sealed and placed in a constant temperature and humidity incubator at 30°C and 60% relative humidity for a 7-day bioleaching experiment, with samples taken every other day. Sampling was conducted entirely in an anaerobic workstation equipped with anaerobic indicators, with oxygen concentration monitored to be below 100 ppm. The pH of the system was measured using a precision pH meter with an accuracy of ±0.01, and the results showed that the pH remained stable within the neutral range of 7.2-7.5 during the leaching process. A portion of the sample was filtered through a 0.22 μm aqueous filter, and the concentrations of lithium, nickel, cobalt, and manganese ions in the leachate were determined using ICP-OES, and the percentage of metal leaching was calculated. After leaching, the metal leaching data for the experimental group were as follows: lithium ion leaching rate reached 78.3%, nickel ion leaching rate was 1.4%, cobalt ion leaching rate was 1.6%, and manganese ion leaching rate was 6.9%. The control group (containing only modified culture medium and NCM622 cathode powder, without common desulfurizing Vibrio) showed significantly lower leaching rates for all metals: lithium ion leaching rate was only 0.9%, nickel ion leaching rate was only 0.4%, cobalt ion leaching rate was only 0.8%, and manganese ion leaching rate was only 0.3%. These results indicate that common desulfurizing Vibrio exhibits significant selective leaching effects on valuable metals in the cathode of spent NCM622 batteries under neutral conditions, and shows selectivity for lithium ion leaching.

[0061] Example 2

[0062] A method for leaching spent NCA battery cathode powder using common desulfurizing Vibrio bacteria under neutral conditions, such as... Figure 1 As shown, the specific operation steps are as follows:

[0063] Step 1: As in step 1a of Example 1, prepare NCA battery cathode powder for bioleaching; as in step 1c of Example 1, prepare a modified culture medium of common desulfurized Vibrio.

[0064] Step 2: As in Step 2 of Example 1, acclimate common desulfurizing Vibrio bacteria to NCA battery cathode powder;

[0065] Step 3: As in Step 3 of Example 1, valuable metals in the waste NCA battery cathode material are bioleached.

[0066] In Example 2, the waste NCA battery cathode powder prepared in step 1, after digestion and measurement, had a lithium content of 71.9 mg / g, a nickel content of 534.4 mg / g, a cobalt content of 38.7 mg / g, and an aluminum content of 16.2 mg / g. The leaching results after 7 days at a solid-liquid ratio of 1.0 g / L were as follows: the pH value was maintained within the range of 7.1-7.4 during leaching; the lithium ion leaching rate was 72.1%, the nickel ion leaching rate was 2.3%, the cobalt ion leaching rate was 1.9%, and the aluminum ion leaching rate was 1.8%. The control group (containing only modified culture medium and NCA cathode powder, without common desulfurizing Vibrio) showed significantly lower leaching rates for all metals: lithium ion leaching rate was only 0.8%, nickel ion leaching rate was only 0.6%, cobalt ion leaching rate was only 0.6%, and aluminum ion leaching rate was only 0.4%.

[0067] Example 3

[0068] A method for leaching waste LFP battery cathode powder using common desulfurizing Vibrio bacteria under neutral conditions, such as... Figure 1 As shown, the specific operation steps are as follows:

[0069] Step 1: As in step 1a of Example 1, prepare LFP battery cathode powder for bioleaching; as in step 1c of Example 1, prepare a modified culture medium of common desulfurized Vibrio.

[0070] Step 2: As in Step 2 of Example 1, acclimate common desulfurization Vibrio bacteria to LFP battery cathode powder;

[0071] Step 3: As in Step 3 of Example 1, valuable metals in the cathode material of waste LFP batteries are bioleached.

[0072] In Example 3, the waste LFP battery cathode powder prepared in step 1, after digestion and measurement, had a lithium content of 35.2 mg / g and an iron content of 283.1 mg / g. The leaching results after 7 days at a solid-liquid ratio of 1.0 g / L were as follows: the pH value was maintained within the range of 7.2-7.5 during the leaching process, with a lithium ion leaching rate of 71.2% and an iron ion leaching rate of 3.4%. The control group (containing only modified culture medium and LFP cathode powder, without common desulfurizing Vibrio) showed significantly lower leaching rates for all metals: a lithium ion leaching rate of only 0.8% and an iron ion leaching rate of only 0.3%.

[0073] Example 4

[0074] A method for leaching spent LCO battery cathode powder using common desulfurizing Vibrio bacteria under neutral conditions, such as... Figure 1 As shown, the specific operation steps are as follows:

[0075] Step 1: As in step 1a of Example 1, prepare LCO battery cathode powder for bioleaching; as in step 1c of Example 1, prepare a modified culture medium of common desulfurized Vibrio.

[0076] Step 2: As in Step 2 of Example 1, acclimate common desulfurization Vibrio bacteria to LCO battery cathode powder;

[0077] Step 3: As in Step 3 of Example 1, valuable metals in the waste LCO battery cathode material are bioleached.

[0078] In Example 4, the waste LCO battery cathode powder prepared in step 1, after digestion and measurement, had a lithium content of 34.5 mg / g and a cobalt content of 550.0 mg / g. The leaching results after 7 days under a solid-liquid ratio of 1.0 g / L were as follows: the pH value was maintained within a neutral range of 7.1-7.3 during the leaching process, with a lithium-ion leaching rate of 72.4% and a cobalt-ion leaching rate of 6.3%. The control group (containing only modified culture medium and LCO cathode powder, without common desulfurizing Vibrio) showed significantly lower leaching rates for all metals: lithium-ion leaching rate was only 0.7%, and cobalt-ion leaching rate was only 0.7%. These results indicate that common desulfurizing Vibrio has a leaching effect on lithium and cobalt ions in waste LCO batteries, especially exhibiting a selective leaching effect on lithium ions.

[0079] Example 5

[0080] A method for leaching spent LMO battery cathode powder using common desulfurizing Vibrio bacteria under neutral conditions, such as... Figure 1 As shown, the specific operation steps are as follows:

[0081] Step 1: As in step 1a of Example 1, prepare LMO battery cathode powder for bioleaching; as in step 1c of Example 1, prepare a modified culture medium of common desulfurized Vibrio.

[0082] Step 2: As in Step 2 of Example 1, acclimate common desulfurization Vibrio bacteria to LMO battery cathode powder;

[0083] Step 3: As in Step 3 of Example 1, valuable metals are bioleached from the cathode material of waste LMO batteries;

[0084] In Example 5, the spent LMO battery cathode powder prepared in step 1, after digestion and measurement, had a lithium content of 36.7 mg / g and a manganese content of 598.4 mg / g. The leaching results after 7 days at a solid-liquid ratio of 2.0 g / L were as follows: the pH value was maintained within a neutral range of 7.3-7.4 during the leaching process, resulting in a lithium-ion leaching rate as high as 94.4% and a manganese-ion leaching rate of 5.3%. The control group (containing only modified culture medium and LMO cathode powder, without common desulfurizing Vibrio) showed significantly lower leaching rates for all metals: a lithium-ion leaching rate of only 0.9% and a manganese-ion leaching rate of only 0.6%. These results indicate that common desulfurizing Vibrio has a highly efficient and selective leaching effect on lithium ions from spent LMO batteries.

Claims

1. A method for leaching spent lithium battery cathode powder in a neutral environment using common desulfurization Vibrio, characterized in that, The method comprises the following steps: The desulfovibrio vulgaris obtained by domestication is inoculated into the modified culture medium at a volume ratio of 5%-10%, and is cultured under 30 DEG C and strict anaerobic conditions to obtain activated desulfovibrio vulgaris liquid; the waste LIBs positive electrode powder is added into the desulfovibrio vulgaris modified culture medium, and then the activated desulfovibrio vulgaris liquid is added to construct a bioleaching system; the system is sealed and placed in a 30 DEG C constant-temperature and 60% relative-humidity incubator for standing culture, the leaching period is 7 days, and a sample is taken every 1 day during the period; the pH value and the bacterial concentration of the system are determined synchronously when the sample is taken; the liquid sample taken out is filtered and separated through a 0.22 mu m water-based microporous filter membrane, the metal ion concentration in the filtrate is detected by using an inductively coupled plasma emission spectrometer, and the leaching percentage of each metal element is calculated accordingly; The domestication process of the domesticated Desulfovibrio vulgaris bacterial strain obtained by domestication is as follows: adding waste LIBs positive electrode powder to the improved culture medium, controlling the initial solid-liquid ratio to be 0.25 g / L, inoculating Desulfovibrio vulgaris according to the initial bacterial concentration of ~10 7 cells / mL, and placing in a constant-temperature culture at 30 DEG C under strict anaerobic conditions; regularly monitoring bacterial growth, and when the bacterial concentration increases to ~10 8 cells / mL, completing the first round of adaptive culture to obtain the first round of cultured bacterial liquid; and using a gradient increasing method to obtain the domesticated Desulfovibrio vulgaris bacterial strain.

2. The method for leaching spent lithium battery cathode powder in a neutral environment using common desulfurization vibrio according to claim 1, characterized in that, The preparation method of the waste LIBs positive electrode powder is as follows: the waste LIBs is disassembled, the positive electrode tab binder polyvinylidene fluoride is dissolved by using N-methyl pyrrolidone, the separator and the negative electrode tab are removed, the positive electrode material and the aluminum foil current collector are peeled off, and the LIBs powder for bioleaching is prepared after crushing, grinding and passing through a 100-mesh screen.

3. The method for leaching spent lithium battery cathode powder in a neutral environment using common desulfurization vibrio according to claim 1, characterized in that, The components of the modified culture medium are as follows: 4.2 g / L of sodium sulfate, 1.8 g / L of sodium bicarbonate, 0.4 g / L of sodium carbonate, 10.0 mL / L of concentrated salt mixed solution, 10.0 mL / L of mineral concentrate, 15.0 mL / L of vitamin mixed solution, 10.0 mL / L of 0.4% calcium chloride monohydrate, 10.0 mL / L of 1.0% magnesium sulfate heptahydrate, 87.6 mL / L of 1 mM selenium tungsten solution and 8.4 mL / L of 60 mM sodium lactate.

4. The method for leaching spent lithium battery cathode powder in a neutral environment using common desulfurization vibrio according to claim 1, characterized in that, When the bioleaching system is constructed, the solid-liquid ratio of the system is controlled to be 1.0 g / L-2.0 g / L; the sampling operation is performed in an anaerobic workstation provided with an anaerobic indicator, the oxygen concentration in the workstation is monitored in real time, and the oxygen concentration is ensured to be stably lower than 100 ppm; the blood cell counting plate counting method is used to quantitatively analyze the bacterial concentration in the system, and the precision pH meter with an accuracy of ±0.01 is used to measure the pH value of the system.

5. The method for leaching spent lithium battery cathode powder in a neutral environment using common desulfurization vibrio according to claim 1, characterized in that, The calculation method of the leaching percentage of the metal elements is as follows: metal leaching percentage = metal ion concentration in the filtrate x filtrate volume / total metal content in the waste LIBs positive electrode powder x 100%.

6. The method for leaching spent lithium battery cathode powder in a neutral environment using common desulfurization vibrio according to claim 1, characterized in that, The enrichment and cryopreservation method of common desulfurization Vibrio is as follows: taking the domesticated bacteria liquid in the logarithmic growth phase, inoculating into fresh modified culture medium without waste LIBs positive electrode powder, carrying out enrichment culture to remove residual mineral particles and expand the bacterial amount; when the bacterial concentration reaches ~2×10 8 cells / mL, the culture is moved into an anaerobic workstation; under a strict anaerobic environment, the bacterial liquid is mixed with 10% (v / v) dimethyl sulfoxide (DMSO) sterile cryopreservation liquid at a volume ratio of 9:1 to make the final concentration of DMSO 1%; then the mixed liquid is divided into anaerobic cryopreservation tubes, 1 mL-2 mL per tube, the tube cap is tightly screwed and sealed with a sealing film, and then immediately placed in a-80℃ refrigerator for preservation.

7. The method for leaching spent lithium battery cathode powder in a neutral environment using common desulfurization vibrio according to claim 1, characterized in that, The method for acclimatization by the gradient increasing method is: taking the bacterial liquid of the first round of culture, transferring to fresh modified culture medium at the same inoculation amount, increasing the solid-liquid ratio to 0.5 g / L, and culturing under the same conditions until the bacterial concentration reaches ~10 8 cells / mL again; in this way, the solid-liquid ratio is increased by 0.25 g / L in each round of transfer culture; after continuous gradient acclimatization for ~20 days, the acclimatized ordinary desulfurizing Vibrio bacteria capable of adapting to the environment of high-concentration waste LIBs positive electrode powder are obtained.

8. The method for leaching spent lithium battery cathode powder in a neutral environment using common desulfurization vibrio according to claim 3, characterized in that, The components of the concentrated salt mixture are: 42.0 g / L of potassium dihydrogen phosphate, 22.0 g / L of potassium phosphate dibasic, 20.0 g / L of ammonium chloride, and 38.0 g / L of potassium chloride; the components of the mineral concentrate are: 3.0 g / L of magnesium sulfate, 3.0 g / L of manganese sulfate monohydrate, 3.0 g / L of sodium chloride, 0.1 g / L of ferrous sulfate heptahydrate, 0.1 g / L of zinc chloride, 0.1 g / L of cobalt chloride hexahydrate, and 0.1 g / L of calcium chloride dihydrate; the components of the vitamin mixture are: 0.002 g / L of biotin, 0.005 g / L of pantothenic acid, 0.0001 g / L of cobalamin, 0.005 g / L of p-aminobenzoic acid, 0.005 g / L of lipoic acid, 0.005 g / L of nicotinic acid, 0.005 g / L of thiamine, 0.005 g / L of riboflavin, 0.01 g / L of pyridoxine hydrochloride, and 0.002 g / L of folic acid; the components of the selenium tungsten solution are: 0.5 g / L of sodium hydroxide, 3 mg / L of sodium selenate pentahydrate, and 4 mg / L of sodium tungstate dihydrate.

9. The method for leaching spent lithium battery cathode powder in a neutral environment using common desulfurization vibrio according to claim 3, characterized in that, After the preparation of the improved medium, high-purity nitrogen gas with a purity of ≥99.99% is introduced for degassing for 2 h, and then the medium is sealed and subjected to high-temperature sterilization to construct a strict anaerobic environment.

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