Recycling method of waste lithium battery, battery-grade lithium carbonate and lithium battery positive electrode material precursor

Abstract

The invention relates to the field of power battery recycling, and discloses a recycling method of a waste lithium battery, battery-grade lithium carbonate and a lithium battery positive electrode material precursor. The method comprises the following steps: (1) hydrogen reduction: pretreating the waste lithium battery to obtain positive electrode powder, and carrying out hydrogen reduction on the positive electrode powder to obtain a reduction product; (2) water leaching is conducted, specifically, the reduction product is subjected to water leaching, leaching liquid and leaching residues are obtained, and the leaching liquid is used for preparing battery-grade lithium carbonate; (3) acid leaching: carrying out oxidation acid leaching on the leaching residues and an acid leaching agent to obtain a nickel-cobalt-manganese leaching solution; and (4) coprecipitation: optionally adding at least one of soluble nickel salt, cobalt salt and manganese salt into the leachate, and then carrying out coprecipitation and aging to obtain the lithium battery positive electrode material precursor. According to the method for treating the lithium battery, the lithium recovery rate is larger than 95%, battery-grade lithium carbonate is obtained, resource recycling is achieved, and the method is short in technological process, low in carbon emission and high in lithium recovery rate.

Description

Technical Field

[0001] The present invention relates to the field of power battery recycling, and in particular to a method for recycling waste lithium batteries, battery-grade lithium carbonate and a lithium battery positive electrode material precursor. Background Art

[0002] In recent decades, the rapid development of the new energy vehicle industry has led to a significant increase in demand for high-performance rechargeable batteries. Ternary power batteries have attracted significant attention due to their high energy density, long cycle life, and superior safety performance. my country's installed power battery capacity increased from 15.7GWh in 2015 to 294.6GWh in 2022, with a compound annual growth rate of 39.8%. As service life increases, ternary batteries will lose capacity and become scrapped due to structural changes in the electrode materials. In 2022, the number of retired lithium batteries in China reached 200,000 tons, and it is expected to reach 1 million tons by 2025. If improperly disposed of, spent ternary batteries can cause serious environmental damage and waste resources such as lithium, nickel, cobalt, and manganese. Therefore, developing methods for recycling spent ternary lithium-ion batteries is crucial for addressing resource shortages and protecting the environment.

[0003] The recycling of waste ternary lithium-ion batteries requires pretreatment. After crushing, sorting and other processes, the current collector, positive electrode powder, negative electrode powder and separator are separated. Among them, the recovery of positive electrode powder has received widespread attention. The recovery methods of positive electrode powder include pyrometallurgical recovery and wet recovery. CN113793995A discloses a method for recovering nickel, cobalt and manganese in the positive electrode materials of waste ternary lithium-ion batteries. The positive electrode material is mixed with crystalline silicon waste and pressed into blocks, reduced and smelted, and separated to obtain nickel-cobalt-manganese alloy and slag blocks. This method has a short process, simple technology and low cost, but it causes lithium to enter the slag phase and is difficult to recover, resulting in a waste of resources.

[0004] To improve lithium recovery, wet recovery of waste battery positive electrode powder is a viable solution. Wet recovery methods generally include leaching, extraction, stripping, and precipitation. Because positive electrode powder contains multiple valuable metals, such as Li, Ni, Co, and Mn, multiple extraction and separation steps are required to obtain the corresponding metal compounds. CN114657378A discloses a method for extracting, separating, and recovering valuable metals from the leachate of waste lithium battery positive electrode material. This method uses four extraction steps to extract Mn, Co, Ni, and Li, respectively, and obtain the corresponding compounds. This method can efficiently separate and recover each metal, but suffers from long process steps and high energy consumption. CN114717419A discloses a method for separating and recovering nickel, cobalt, manganese, and lithium from waste ternary lithium batteries. The positive electrode powder is subjected to a reduction acid leaching process, and Ni, Mn, and Co are separated by extraction and stripping. Finally, lithium is precipitated in the raffinate to produce Li2CO3. This method offers high separation efficiency and product purity, but because lithium is present at the end of the recovery process, the lithium recovery rate is relatively low.

[0005] In order to avoid the problem of low lithium recovery rate, a method for recovering valuable metals from lithium batteries using a combined pyrometallurgical and hydrometallurgical process has attracted widespread attention. CN106129511A discloses a method for comprehensively recovering valuable metals from waste lithium-ion battery materials, wherein the positive electrode material of the lithium-ion battery is mixed with a solid carbon reducing agent and roasted and water-leached to preferentially recover lithium, and the water-leached residue is leached, extracted, and other methods to prepare the corresponding compound. CN112374511A discloses a method for recovering lithium carbonate and a ternary precursor from waste ternary lithium batteries, wherein the graphite contained in the black powder is used as a reducing agent, and lithium is preferentially recovered by self-reduction-water leaching, and the lithium slag is directly leached with sulfuric acid and impurities are removed to prepare a ternary positive electrode material precursor. The carbon reduction-preferential lithium extraction method can ensure a high lithium recovery rate, but it has high energy consumption and large carbon emissions.

[0006] In summary, the above methods can achieve resource utilization of spent ternary lithium-ion cathode powder, but they have problems such as long process, high energy consumption, high carbon emissions, and low lithium recovery rate. Therefore, it is urgent to develop a short-process method for the reuse of spent ternary lithium-ion cathode powder. Summary of the Invention

[0007] The present invention aims to overcome the problems of the prior art, such as long processes, high energy consumption, and low lithium recovery rates, by providing a method for recycling used lithium batteries, battery-grade lithium carbonate, and a precursor for lithium battery cathode materials. This method has a short process flow, low production energy consumption, and low carbon emissions, and preferentially extracts high-purity lithium carbonate, thereby improving lithium recovery rates.

[0008] In order to achieve the above object, the present invention provides a method for recycling waste lithium batteries, wherein the method comprises the following steps:

[0009] (1) Hydrogen reduction: pre-treating waste lithium batteries to obtain positive electrode powder, and then subjecting the positive electrode powder to hydrogen reduction to obtain a reduction product;

[0010] (2) water leaching: leaching the reduced product in water to obtain a leachate and a leachate residue, wherein the leachate is used to prepare battery-grade lithium carbonate;

[0011] (3) acid leaching: subjecting the leached residue and the acid leaching agent to oxidative acid leaching to obtain a nickel, cobalt and manganese leachate;

[0012] (4) Coprecipitation: optionally adding at least one of a soluble nickel salt, a cobalt salt and a manganese salt to the leachate, and then coprecipitating and aging to obtain a lithium battery positive electrode material precursor.

[0013] The second aspect of the present invention provides a battery-grade lithium carbonate, which is prepared by the method described in the first aspect.

[0014] The third aspect of the present invention provides a lithium battery positive electrode material precursor, which is prepared by the method described in the first aspect.

[0015] Through the above technical solution, the present invention has the following beneficial effects:

[0016] (1) The present invention provides a method for recycling waste lithium batteries, wherein the waste lithium-ion battery positive electrode powder obtained by pretreatment is recycled and then resynthesized into new battery-grade lithium carbonate and nickel-cobalt-manganese positive electrode material precursors. The obtained battery-grade lithium carbonate and nickel-cobalt-manganese positive electrode material precursors have high yields and purities, thereby achieving effective recycling of resources.

[0017] (2) The method for recycling waste lithium batteries provided by the present invention preferentially extracts lithium by subjecting waste lithium-ion battery positive electrode powder to hydrogen reduction and water immersion treatment. The overall process route has a lithium recovery rate of up to 95%, achieving preferential, efficient and high-purity recovery of lithium, solving the problem of low lithium ion recovery rate in the current recycling industry.

[0018] (3) The present invention provides a method for recycling waste lithium batteries. The hydrogen reduction product is subjected to water immersion, precipitation and purification processes to directly prepare battery-grade lithium carbonate, without the need for multiple pure water washings, thereby significantly reducing the amount of wastewater generated. Preferably, the lithium tail liquid obtained by precipitation is returned to the lithium precipitation process after extraction and stripping treatment, and lithium is extracted again, thereby achieving efficient and high-value lithium recovery. The raffinate obtained by extraction can be reused to extract metals again without generating secondary pollution.

[0019] (4) The present invention provides a method for recycling waste lithium batteries. The nickel, cobalt and manganese leaching residue obtained by water leaching is subjected to oxidative acid leaching, impurity removal and co-precipitation to directly obtain a battery positive electrode material precursor, avoiding the nickel, cobalt and manganese extraction and separation steps, shortening the process flow; avoiding the use of carbon-based reducing agents, greatly improving the recovery rate of valuable metals, and reducing carbon emissions;

[0020] (5) The method for recycling waste lithium batteries provided by the present invention has a short process flow, is conducive to industrial large-scale production, meets the needs of the current industry, and has a very broad application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention but do not constitute a limitation of the present invention.

[0022] Figure 1 The present invention is a process flow chart of the method for recycling waste lithium batteries. DETAILED DESCRIPTION

[0023] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0024] A first aspect of the present invention provides a method for recycling waste lithium-ion batteries, wherein the method comprises the following steps:

[0025] (1) Hydrogen reduction: pre-treating waste lithium batteries to obtain positive electrode powder, and then subjecting the positive electrode powder to hydrogen reduction to obtain a reduction product;

[0026] (2) water leaching: leaching the reduced product in water to obtain a leachate and a leachate residue, wherein the leachate is used to prepare battery-grade lithium carbonate;

[0027] (3) acid leaching: subjecting the leached residue and the acid leaching agent to oxidative acid leaching to obtain a nickel, cobalt and manganese leachate;

[0028] (4) Coprecipitation: optionally adding at least one of a soluble nickel salt, a cobalt salt and a manganese salt to the leachate, and then coprecipitating and aging to obtain a lithium battery positive electrode material precursor.

[0029] The present invention provides a method for recycling waste lithium batteries. The waste lithium-ion battery positive electrode powder obtained by pretreatment is recycled. After the positive electrode powder is subjected to hydrogen reduction and water leaching, lithium is preferentially extracted, and the lithium recovery rate can reach 95%. The leachate obtained in the water leaching process of the present invention directly obtains battery-grade lithium carbonate. The present invention subjects the leached residue obtained by water leaching to oxidative acid leaching, impurity removal and coprecipitation treatment to directly obtain a battery positive electrode material precursor, avoiding the steps of nickel, cobalt and manganese extraction and separation, shortening the process flow, avoiding the use of carbon-based reducing agents, greatly improving the recovery rate of valuable metals, and reducing carbon emissions.

[0030] In the present invention, the type of the waste lithium battery is not particularly limited. For example, it can be at least one of waste lithium cobalt oxide batteries, waste lithium manganese oxide batteries and waste nickel-cobalt-manganese ternary lithium batteries, preferably waste nickel-cobalt-manganese ternary lithium batteries.

[0031] In some embodiments of the present invention, preferably, in step (1), the pretreatment is to discharge, disassemble and crush the waste batteries to obtain positive electrode powder. In the present invention, the particle size of the positive electrode powder is not particularly limited and can be a powder in the conventional sense in the art.

[0032] In the present invention, preferably, the waste lithium batteries are subjected to a discharge treatment, and then the discharged waste lithium batteries are disassembled to separate the positive electrode materials, and then the positive electrode materials are crushed to obtain positive electrode powder.

[0033] In the present invention, the specific operation method of the discharge treatment can adopt the conventional discharge method in the art. Preferably, the discharge treatment uses immersion in a 5-15wt% sodium chloride solution. In the present invention, the specific operation method of the disassembly and crushing can adopt the conventional method in the art and will not be described in detail here.

[0034] In the present invention, the specific operation method of the hydrogen reduction treatment may include: placing the positive electrode powder in a hydrogen reduction furnace, introducing hydrogen to perform hydrogen reduction treatment, and obtaining a reduction product.

[0035] In some embodiments of the present invention, the reduction product preferably includes a lithium compound, nickel, cobalt, and manganese elements, and subvalent oxides. In the present invention, the lithium compound includes soluble LiOH, Li2O, and a small amount of Li2CO3; and the subvalent oxides include nickel oxide, cobalt oxide, and manganese oxide.

[0036] In the present invention, the thermodynamic feasibility of the hydrogen reduction reaction is determined by calculating the relationship between the Gibbs free energy of the hydrogen reduction reaction and the temperature. The inventors of the present invention have found that within the temperature range of 200-1000°C, the Gibbs free energy ΔG of the following reactions is less than 0, that is, the following reactions can proceed within the temperature range, that is, the positive electrode powder can be subjected to hydrogen reduction treatment to obtain the following reduction products. In the present invention, the reaction equations mainly involved in hydrogen reduction are as follows:

[0037] NiO+H2(g)=Ni+H2O(g)

[0038] CoO+H2(g)=Co+H2O(g)

[0039] MnO2+H2(g)=MnO+H2O(g)

[0040] Li2O+H2(g)+1 / 2O2(g)=2LiOH

[0041] In some embodiments of the present invention, the hydrogen reduction temperature is preferably 400-700° C., for example, 400° C., 450° C., 500° C., 550° C., 600° C., 650° C., 700° C., and any value in a range consisting of any two values, preferably 450-550° C. In the present invention, a reduction temperature lower than 400° C. will result in insufficient reduction power, and the ternary cathode material cannot be completely decomposed, resulting in poor lithium selectivity during the water leaching process; while a temperature higher than 700° C. will cause lithium compounds to react with MnO to form LiMnO2, resulting in a reduced lithium yield.

[0042] In some embodiments of the present invention, preferably, the hydrogen reduction time is 0.5-4h, for example, it can be 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, and any value in the range of any two values, preferably 1-2h.

[0043] In some embodiments of the present invention, preferably, relative to 1000g of positive electrode powder, the flow rate of H2 introduced during hydrogen reduction is 0.2-0.8L / min, for example, it can be 0.2L / min, 0.3L / min, 0.4L / min, 0.5L / min, 0.6L / min, 0.7L / min, 0.8L / min, and any value in the range of any two values, preferably 0.3-0.5L / min.

[0044] In the present invention, the hydrogen reduction time and the H2 flow rate jointly determine the amount of H2 in the hydrogen reduction and the reaction efficiency. If the amount of H2 is small, the reaction of the ternary positive electrode material is incomplete; if the amount of H2 is excessive, the generated low-valent oxides NiO and CoO are further reduced to elemental Ni and Co, and the subsequent extraction process requires the addition of oxidants for dissolution, which increases the recovery cost; if the H2 flow rate is low, the reaction efficiency is low, the time required is long, and the production efficiency is low; and if the H2 flow rate is too high, its utilization rate will be low, and it will be discharged due to incomplete reaction.

[0045] In the present invention, the temperature, time and flow rate of the hydrogen reduction are controlled within the above ranges, which is conducive to phase reconstruction, thereby obtaining reduction products Li2O, LiOH, NiO, CoO, MnO, Ni, and Co. After reduction, Li2O and LiOH come into contact with carbon dioxide in the air to generate a small amount of Li2CO3.

[0046] In the present invention, the reduction product obtained in step (1) is mixed with water, and water leaching is performed under stirring conditions, followed by solid-liquid separation to obtain a leachate and a leach residue. The stirring conditions of the present invention are not particularly limited, as long as the reduction product and water are in full contact.

[0047] In the present invention, the reduction product obtained by water leaching and dissolving step (1) has LiOH and Li2O in it which are water-soluble substances, while nickel, cobalt and manganese elements and nickel, cobalt and manganese suboxides are insoluble in water and cannot be leached out by water. Therefore, water leaching is conducive to the selective separation of lithium from nickel, cobalt and manganese, thereby shortening the process flow.

[0048] In the present invention, the solid-liquid separation is usually achieved by filtration.

[0049] In some embodiments of the present invention, preferably, the leaching temperature of the water immersion is 20-95°C, for example, 20°C, 25°C, 30°C, 35°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 95°C, and any value in the range of any two values, preferably 70-90°C; the leaching time of the water immersion is 0.5-4h, for example, 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, and any value in the range of any two values, preferably 1-2h. In the present invention, the higher the leaching temperature of the water immersion, the higher the activity of the reactants, and the easier it is to leach lithium, but if the temperature is too high, the energy consumption is higher and water evaporation is serious; controlling the temperature and time of the water immersion within the range is conducive to improving the leaching efficiency, the high lithium leaching rate, and the high economic benefit.

[0050] In some embodiments of the present invention, preferably, the liquid-to-solid mass ratio of the water immersion is 4.5-30:1, for example, it can be 4.5:1, 5:1, 10:1, 15:1, 20:1, 25:1, 30:1, and any value in the range of any two values, preferably 5-10:1. In the present invention, if the liquid-to-solid ratio of the water immersion is too low, it will lead to insufficient contact between the reduction product and water, resulting in a low lithium leaching rate, and the lithium concentration is too high, resulting in saturated precipitation; if the liquid-to-solid ratio is too high, the lithium leaching rate is high, but the excessively high liquid-to-solid ratio will result in a low lithium concentration, low efficiency of subsequent lithium extraction by precipitation, and low direct lithium recovery rate.

[0051] In the present invention, the leaching temperature, leaching time and liquid-to-solid mass ratio of the water leaching are controlled within the above ranges, which is conducive to the dissolution of the lithium compound, thereby facilitating the selective separation of lithium from nickel, cobalt and manganese, achieving selective recovery of lithium, and shortening the process flow.

[0052] In some embodiments of the present invention, preferably, in step (2), the obtained leachate is subjected to lithium precipitation to obtain crude lithium carbonate and lithium precipitation tail liquid, and the crude lithium carbonate is refined to obtain battery-grade lithium carbonate; the lithium precipitation tail liquid is extracted and stripped, and the obtained lithium-containing aqueous phase is returned to the lithium precipitation process; and the raffinate obtained by extraction is returned to the water leaching process for reuse.

[0053] In the present invention, the method for lithium precipitation can adopt various methods for lithium precipitation in the field. Preferably, the specific method for lithium precipitation includes: adding carbonate or introducing carbon dioxide to the obtained leachate, performing carbonation leaching under stirring, solid-liquid separation to obtain crude lithium carbonate precipitation, and refining the crude lithium carbonate to obtain battery-grade lithium carbonate. In the present invention, the leachate obtained by water leaching is subjected to lithium precipitation and refining to directly prepare battery-grade lithium carbonate, without the need for multiple pure water washings, which greatly reduces the amount of wastewater generated.

[0054] In the present invention, the refining method can adopt any method known in the art for purifying crude lithium carbonate to prepare battery-grade lithium carbonate, which will not be described in detail here.

[0055] In the present invention, the carbonate may be any carbonate known in the art. Preferably, the carbonate is at least one of potassium carbonate, sodium carbonate and sodium bicarbonate.

[0056] In the present invention, the conditions for introducing carbon dioxide are not particularly limited, as long as it can react with the leachate obtained in step (2) to perform carbonation leaching to obtain crude lithium carbonate. Preferably, the flow rate of the introduced carbon dioxide can be 400-1000 mL / min.

[0057] In some embodiments of the present invention, preferably, the lithium precipitation time is 0.5-4h, for example, it can be 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, and any value in the range of any two numerical values; the temperature of the lithium precipitation reaction is not particularly limited, for example, the temperature can be room temperature (25°C).

[0058] In the present invention, the stirring conditions in the lithium precipitation process are not particularly limited, as long as the leachate can be fully contacted with the carbonate or carbon dioxide. Preferably, the stirring speed can be 200-600 rpm.

[0059] In the present invention, in step (2), the lithium in the lithium precipitation tail liquid is extracted into the organic phase by an extractant to obtain a lithium-containing organic phase and a raffinate; then, a lithium-containing aqueous phase is obtained by back-extraction with a stripping agent, and the lithium-containing aqueous phase is returned to the lithium precipitation process for lithium extraction, thereby increasing the lithium concentration and achieving efficient and high-value recovery of lithium; the raffinate is reused to extract lithium and valuable metals again without generating secondary pollution.

[0060] In the present invention, the extraction and stripping are both carried out at room temperature (25°C).

[0061] In the present invention, the extractant can be any extractant known in the art for extracting lithium. Preferably, the extractant can be tributyl phosphate-sulfonated kerosene. The tributyl phosphate-sulfonated kerosene extractant described in the present invention is a tributyl phosphate extractant diluted with sulfonated kerosene.

[0062] In some embodiments of the present invention, preferably, the volume fraction of tributyl phosphate is 40-80%.

[0063] In some embodiments of the present invention, the volume ratio of the oil phase to the aqueous phase during the extraction is preferably 1:5-2:1, preferably 1:4-1:2. In the present invention, the oil phase is a tributyl phosphate-sulfonated kerosene extractant, and the aqueous phase is a lithium precipitate tail liquor. Controlling the volume ratio of the oil phase to the aqueous phase during the extraction within the aforementioned range facilitates lithium extraction, allowing lithium from the lithium precipitate tail liquor to enter the organic phase, increasing the lithium concentration and facilitating efficient and high-value lithium recovery.

[0064] In the present invention, the stripping agent can be any stripping agent known in the art that can be used for stripping lithium. Preferably, the stripping agent used in the stripping is selected from at least one of hydrochloric acid, sulfuric acid and nitric acid, preferably hydrochloric acid.

[0065] In some embodiments of the present invention, preferably, the concentration of the stripping agent is 1-6 mol / L.

[0066] In some embodiments of the present invention, the volume ratio of the oil phase to the aqueous phase in the stripping process is preferably 1:2-4.5:1, preferably 2:1-4:1. In the present invention, the oil phase is the lithium-containing organic phase obtained by extraction, and the aqueous phase is the stripping agent. In the present invention, controlling the volume ratio of the oil phase to the aqueous phase in the stripping process within the above range is beneficial for stripping lithium, stripping lithium from the organic phase into the aqueous phase, further increasing the lithium concentration and facilitating efficient and high-value recovery of lithium.

[0067] In the present invention, the leaching residue obtained in step (2) is mixed with an acid leaching agent and an oxidant, and subjected to oxidative acid leaching treatment to obtain a leachate containing nickel, cobalt and manganese.

[0068] In the present invention, the acid leaching agent in step (3) can be any acid leaching agent known in the art, preferably an inorganic acid leaching agent, more preferably at least one selected from sulfuric acid, hydrochloric acid and nitric acid.

[0069] In some embodiments of the present invention, preferably, the concentration of the pickling agent is 2-6 mol / L.

[0070] In some embodiments of the present invention, preferably, the oxidizing acid leaching uses an oxidizing agent selected from at least one of air, oxygen and hydrogen peroxide, preferably hydrogen peroxide.

[0071] In some embodiments of the present invention, preferably, the volume fraction of the hydrogen peroxide is 5-20%.

[0072] In some embodiments of the present invention, preferably, the liquid-to-solid mass ratio in the oxidizing acid leaching is 4.5-30: 1, preferably 5-10: 1. In the present invention, the liquid is the acid leaching agent and the solid is the leached residue.

[0073] In the present invention, the conditions of the oxidative acid leaching treatment in step (3) are not particularly limited. Preferably, the leaching temperature of the oxidative acid leaching can be 20-95°C, preferably 70-90°C; the leaching time of the oxidative acid leaching can be 0.5-4h, preferably 1-2h.

[0074] In some embodiments of the present invention, preferably, step (3) further comprises: removing impurities from the obtained nickel-cobalt-manganese leaching solution to obtain a purified solution.

[0075] In some embodiments of the present invention, preferably, the specific step of removing impurities includes: adjusting the pH of the obtained leachate to remove aluminum, iron and copper to obtain a purified solution.

[0076] In the present invention, the impurity removal is to remove the iron ions, aluminum ions and copper ions in the leachate, so that the impurity metals are precipitated in the form of hydroxide precipitates, and then filtered through a precision filter to remove the precipitates.

[0077] In some embodiments of the present invention, preferably, the specific step of removing impurities includes: adjusting the pH of the obtained leachate to perform preliminary removal of aluminum, iron and copper, and then adding manganese sulfide to the obtained solution after preliminary removal of aluminum, iron and copper to perform deep removal of iron and copper to obtain a nickel-cobalt-manganese purified solution.

[0078] In the present invention, preferably, in the preliminary impurity removal step, sodium carbonate is added to the leachate to react, and the pH of the solution is controlled to be 3.5-5, so that aluminum reacts with sodium carbonate to form aluminum slag (aluminum carbonate decomposes into aluminum hydroxide when it comes into contact with water), trivalent iron ions are hydrolyzed to form ferric hydroxide precipitates, and divalent copper is hydrolyzed to form copper hydroxide precipitates. After solid-liquid separation, the purpose of preliminary removal of aluminum, iron and copper is achieved. The main reaction equations involved are as follows:

[0079] 2Al 3+ +3Na2CO3=Al2(CO3)3+6Na +

[0080] Al2(CO3)3+3H2O=2Al(OH)3↓+3CO2

[0081] H2SO4+Na2CO3=Na2SO4+H2O+3CO2

[0082] Fe 3+ +3H2O=Fe(OH)3↓+3H +

[0083] Cu 2+ +2H2O=Cu(OH)2↓+2H +

[0084] In the present invention, preferably, in the deep iron and copper removal step, a stoichiometric amount of manganese sulfide is added to the solution after preliminary aluminum, iron, and copper removal. After sufficient reaction, the precipitate is filtered out to reduce the copper concentration in the resulting purified solution to less than 10 ppm, thereby achieving the purpose of deep copper removal and further removing iron. The main reaction equations involved are as follows:

[0085] Cu 2+ +MnS=Mn 2+ +CuS↓

[0086] 2Fe 3+ +3MnS=3Mn 2+ +Fe2S3↓

[0087] Fe2S3=2FeS↓+S↓

[0088] In the present invention, the solubility product Ksp of manganese sulfide is 3×10 -14 The solubility products Ksp of copper sulfide and iron sulfide are 1.27×10 -36 and 1×10 -88 The solubility product reflects the solubility of sparingly soluble electrolytes. Because Fe2S3 is unstable, it further decomposes into FeS precipitate and sulfur in aqueous solution. Therefore, adding a stoichiometric amount of manganese sulfide to the acid leaching solution can achieve deep removal of copper and iron.

[0089] In some embodiments of the present invention, preferably, the total molar ratio of the manganese sulfide to the copper and iron in the solution after preliminary removal of aluminum, iron and copper is 1.05-2:1, preferably 1.1-1.5:1.

[0090] In some embodiments of the present invention, preferably, the pH of the impurity removal is 3.5-5. In the present invention, in the impurity removal step, the pH of the obtained leachate is adjusted to 3.5-5. Controlling the pH of the leachate within the above range is conducive to precipitating aluminum, iron, and copper in the form of their respective hydroxides, thereby achieving the purpose of removing aluminum, iron, and copper.

[0091] In some embodiments of the present invention, preferably, in step (4), the molar ratios of nickel, cobalt and manganese in the positive electrode material precursor are 1:1:1, 6:2:2 and 8:1:1 by regulating the amounts of soluble nickel salt, cobalt salt and manganese salt added and the conditions of the coprecipitation reaction.

[0092] In the present invention, preferably, the concentrations of nickel, cobalt and manganese in the purified solution are detected, and at least one soluble nickel salt, cobalt salt and manganese salt is optionally added to the nickel-cobalt-manganese purified solution to adjust the molar ratio so that the molar ratio of nickel, cobalt and manganese in the obtained positive electrode material precursor is 1:1:1, 6:2:2 and 8:1:1.

[0093] In the present invention, inductively coupled plasma optical emission spectrometer (ICP-OES) is used to determine the contents of nickel, cobalt and manganese in the purified solution.

[0094] In the present invention, the salt among the soluble nickel salt, cobalt salt and manganese salt can be any soluble salt known in the art. Preferably, the salt among the soluble nickel salt, cobalt salt and manganese salt is independently selected from at least one of sulfate, nitrate and chloride, and more preferably sulfate.

[0095] In the present invention, preferably, an alkali solution, an aqueous ammonia solution, and a purified solution are added to a coprecipitation reactor to carry out a coprecipitation reaction. After the coprecipitation reaction is completed, the resulting slurry is mechanically stirred and aged, then washed with deionized water and dried to obtain a cathode material precursor. The method of the present invention avoids the nickel, cobalt, and manganese extraction and separation steps, shortening the process flow; and avoids the use of carbon-based reducing agents, significantly improving the recovery rate of valuable metals and reducing carbon emissions.

[0096] In some embodiments of the present invention, preferably, the pH of the leachate is further adjusted by adding alkali solution and ammonia solution.

[0097] In the present invention, the base can be any base known in the art. Preferably, the base is a base, more preferably at least one selected from sodium hydroxide, potassium hydroxide, calcium hydroxide and lithium hydroxide.

[0098] In some embodiments of the present invention, preferably, the concentration of the alkali solution is 6-8 mol / L.

[0099] In some embodiments of the present invention, preferably, the concentration of the ammonia water is 2-3 mol / L.

[0100] In the present invention, the conditions for the coprecipitation reaction are not particularly limited. Preferably, the pH of the coprecipitation reaction is 7-8.5; the temperature of the coprecipitation reaction is 20-75°C, preferably 50-70°C; and the time of the coprecipitation reaction is not particularly limited. For example, the coprecipitation reaction time can be 2-20 hours, preferably 6-12 hours. In the present invention, controlling the coprecipitation reaction conditions within the above range is conducive to precipitating nickel, cobalt and manganese from the purified liquid to obtain a nickel, cobalt and manganese precipitate, thereby facilitating the production of a nickel, cobalt and manganese cathode material precursor.

[0101] In the present invention, the aging conditions are not particularly limited, as long as the nickel-cobalt-manganese precipitate obtained by the coprecipitation reaction can be fully settled. Preferably, the aging time is 2-5 hours, and the aging temperature is 30-80°C.

[0102] In the present invention, the method further comprises washing the precipitate obtained by aging with deionized water and drying to obtain a positive electrode material precursor. The drying conditions of the present invention are not particularly limited, for example, the precipitate can be dried in a forced air drying oven at 60-80°C for 10-12 hours.

[0103] In a preferred embodiment of the present invention, Figure 1 As shown, the method for recycling waste lithium batteries includes the following steps:

[0104] (1) Hydrogen reduction: Pre-treat waste lithium batteries to obtain positive electrode powder. Place 1000 g of positive electrode powder in a hydrogen reduction furnace, introduce H2 at a flow rate of 0.2-0.8 L / min at a temperature of 400-700°C, and perform hydrogen reduction treatment for 0.5-4 h to obtain a reduced product.

[0105] (2) Water leaching: taking the reduction product of step (1), adding water thereto at a liquid-to-solid ratio of 4.5-30:1 for water leaching, separating the solid and the liquid to obtain a lithium-containing leachate and a nickel-cobalt-manganese leach residue, subjecting the lithium-containing leachate to lithium precipitation to obtain crude lithium carbonate and a lithium precipitation tail liquid, refining the crude lithium carbonate to obtain battery-grade lithium carbonate; extracting and stripping the lithium precipitation tail liquid, and returning the obtained lithium-containing aqueous phase to the lithium precipitation step; and returning the extracted raffinate to the water leaching step for reuse;

[0106] (3) acid leaching: mixing the nickel-cobalt-manganese leaching residue obtained in step (2) with a dilute sulfuric acid solution and hydrogen peroxide, and performing oxidative acid leaching to obtain a nickel-cobalt-manganese leaching solution; adding sodium sulfate to the nickel-cobalt-manganese leaching solution to adjust the pH, and performing preliminary removal of aluminum, iron, and copper; and then adding manganese sulfide to the obtained solution after preliminary removal of aluminum, iron, and copper to perform deep removal of iron and copper to obtain a purified solution;

[0107] (4) Coprecipitation: optionally adding at least one of soluble nickel salt, cobalt salt and manganese salt to the purified liquid, then coprecipitating and aging, filtering and drying to obtain a positive electrode material precursor.

[0108] The second aspect of the present invention provides a battery-grade lithium carbonate, which is prepared by the method described in the first aspect.

[0109] In the present invention, the lithium carbonate prepared by the waste lithium battery recycling method has a purity of more than 99.5%, meeting the standard of battery-grade lithium carbonate (YS / T582-2013).

[0110] The third aspect of the present invention provides a lithium battery positive electrode material precursor, which is prepared by the method described in the first aspect.

[0111] In the present invention, the lithium battery positive electrode material precursor prepared by the method for recycling waste lithium batteries has a content of the main elements nickel, cobalt and manganese that meets the content of nickel, cobalt and manganese in the positive electrode material precursor and reaches the standard of nickel, cobalt and manganese ternary composite hydroxide (GB / T 26300-2020).

[0112] The present invention will be described in detail below through examples.

[0113] Example 1

[0114] (1) Hydrogen reduction: waste ternary battery powder containing lithium-ion battery positive electrode material was discharged, disassembled and crushed to obtain 1000 g of positive electrode powder. The positive electrode powder was placed in a hydrogen reduction furnace, and H2 was introduced at a flow rate of 0.4 L / min at a temperature of 500°C for 1 hour to obtain a reduced product;

[0115] (2) Water leaching: taking the reduction product of step (1), adding water thereto at a liquid-solid ratio of 5:1, leaching at a temperature of 90°C for 1h, filtering and separating to obtain a lithium-containing leachate and a nickel-cobalt-manganese leach residue, introducing CO2 into the lithium-containing leachate and stirring at a speed of 600rpm for 1h to precipitate lithium, and obtaining battery-grade lithium carbonate with a purity of 99.8% after refining; adding a mixed extractant of 60vol% tributyl phosphate and 40vol% sulfonated kerosene to the lithium precipitation tail liquid at a volume ratio of 1:4 between the organic phase and the aqueous phase, and retaining the lithium in the lithium precipitation tail liquid in the organic phase by the mixed extractant, while all the remaining substances enter the raffinate; adding a 6mol / L dilute hydrochloric acid stripping agent to the organic phase at a volume ratio of 4:1 between the organic phase and the aqueous phase, stripping the lithium in the organic phase by the stripping agent to obtain a lithium-containing aqueous phase, and then returning to the lithium precipitation process; returning the raffinate obtained by extraction to the water leaching process for reuse; the lithium recovery rate of the whole process is 98.2%;

[0116] (3) acid leaching: adding the nickel-cobalt-manganese leaching residue obtained in step (2) to a 2 mol / L dilute sulfuric acid solution at a liquid-solid ratio of 10:1, then adding H2O2 with a volume fraction of 5%, leaching at 70°C for 2 h to obtain a nickel-cobalt-manganese leaching solution, adding sodium carbonate to the leaching solution to adjust the pH to 5, filtering to obtain a preliminary iron-aluminum-copper-removed liquid; then adding manganese sulfide to the preliminary iron-aluminum-copper-removed liquid to deeply remove iron and copper, the molar amount of manganese sulfide added being 1.5 times the total molar amount of copper and iron in the preliminary iron-aluminum-copper-removed liquid, filtering to obtain a nickel-cobalt-manganese purified liquid;

[0117] (4) Coprecipitation: Detect the concentrations of nickel, cobalt and manganese in the purified liquid, add soluble nickel sulfate, cobalt sulfate and manganese sulfate to the purified liquid to adjust the ratio so that the molar ratio of nickel, cobalt and manganese in the purified liquid is 8:1:1, then add 6 mol / L sodium hydroxide solution and 3 mol / L ammonia solution, maintain the solution pH at 8, and the reaction temperature at 65°C. After the reaction is completed, age for 5 hours, filter and dry to obtain a positive electrode material precursor.

[0118] The test results of the positive electrode material precursor obtained by the method for recycling waste lithium-ion battery positive electrode powder according to the present invention are shown in Table 1.

[0119] Example 2

[0120] (1) Hydrogen reduction: waste ternary battery powder containing lithium-ion battery positive electrode material was discharged, disassembled and crushed to obtain 1000 g of positive electrode powder. The positive electrode powder was placed in a hydrogen reduction furnace, and H2 was introduced at a flow rate of 0.3 L / min at a temperature of 550°C for 1.5 h to obtain a reduced product;

[0121] (2) Water leaching: taking the reduction product of step (1), adding water thereto at a liquid-solid ratio of 10:1, leaching at a temperature of 70°C for 2h, filtering and separating to obtain a lithium-containing leachate and a nickel-cobalt-manganese leach residue, adding sodium carbonate to the lithium-containing leachate and stirring at a speed of 400rpm for 1h to precipitate lithium, and obtaining battery-grade lithium carbonate with a purity of 99.9% after refining; adding a mixed extractant of 40vol% tributyl phosphate and 60vol% sulfonated kerosene to the lithium precipitation tail liquid at a volume ratio of 1:2 between the organic phase and the aqueous phase, so that the lithium in the lithium precipitation tail liquid is retained in the organic phase by the mixed extractant, and all the remaining substances enter the raffinate; adding a 4mol / L dilute hydrochloric acid stripping agent to the organic phase at a volume ratio of 2:1 between the organic phase and the aqueous phase, stripping the lithium in the organic phase by the stripping agent to obtain a lithium-containing aqueous phase, and then returning to the lithium precipitation process; returning the raffinate obtained by extraction to the water leaching process for reuse; the lithium recovery rate of the whole process is 98.5%;

[0122] (3) acid leaching: adding the nickel-cobalt-manganese leaching residue obtained in step (2) to a 4 mol / L dilute sulfuric acid solution at a liquid-solid ratio of 5:1, then adding 10% H2O2 by volume, leaching at 90°C for 2 h to obtain a nickel-cobalt-manganese leaching solution, adding sodium carbonate to the leaching solution to adjust the pH to 4.5, filtering to obtain a preliminary iron-aluminum-copper-removed solution; then adding manganese sulfide to the preliminary iron-aluminum-copper-removed solution for deep impurity removal, wherein the molar amount of manganese sulfide added is 1.1 times the total molar amount of copper and iron in the preliminary iron-aluminum-copper-removed solution, and filtering to obtain a nickel-cobalt-manganese purified solution;

[0123] (4) Coprecipitation: Detect the concentrations of nickel, cobalt and manganese in the purified liquid, add soluble nickel sulfate, cobalt sulfate and manganese sulfate to the purified liquid to adjust the ratio so that the molar ratio of nickel, cobalt and manganese in the purified liquid is 1:1:1, then add 8 mol / L sodium hydroxide solution and 2 mol / L ammonia solution, maintain the solution pH at 8.5, the reaction temperature is 60°C, and after the reaction is completed, age for 4 hours, filter and dry to obtain a positive electrode material precursor.

[0124] The test results of the positive electrode material precursor obtained by the method for recycling waste lithium-ion battery positive electrode powder according to the present invention are shown in Table 1.

[0125] Example 3

[0126] (1) Hydrogen reduction: waste ternary battery powder containing lithium-ion battery positive electrode material was discharged, disassembled and crushed to obtain 1000 g of positive electrode powder. The positive electrode powder was placed in a hydrogen reduction furnace, and H2 was introduced at a flow rate of 0.8 L / min at a temperature of 700°C for 1 hour to obtain a reduced product;

[0127] (2) Water leaching: taking the reduction product of step (1), adding water thereto at a liquid-solid ratio of 30:1, leaching at a temperature of 25°C for 4h, filtering and separating to obtain a lithium-containing leachate and a nickel-cobalt-manganese leach residue, adding potassium carbonate to the lithium-containing leachate and stirring at a speed of 400rpm for 4h to precipitate lithium, and obtaining battery-grade lithium carbonate with a purity of 99.6% after refining; adding a mixed extractant of 80vol% tributyl phosphate and 20vol% sulfonated kerosene to the lithium precipitation tail liquid at a volume ratio of 1:4 between the organic phase and the aqueous phase, and retaining the lithium in the lithium precipitation tail liquid in the organic phase by the mixed extractant, and all the remaining substances enter the raffinate; adding a 6mol / L dilute hydrochloric acid stripping agent to the organic phase at a volume ratio of 4:1 between the organic phase and the aqueous phase, stripping the lithium in the organic phase by the stripping agent to obtain a lithium-containing aqueous phase, and then returning to the lithium precipitation process; returning the raffinate obtained by extraction to the water leaching process for reuse; the lithium recovery rate of the whole process is 96.7%;

[0128] (3) acid leaching: adding the nickel-cobalt-manganese leaching residue obtained in step (2) to a 2 mol / L dilute sulfuric acid solution at a liquid-solid ratio of 30:1, then adding 5% by volume of H2O2, leaching at 20°C for 4 h to obtain a nickel-cobalt-manganese leaching solution, adding sodium carbonate to the leaching solution to adjust the pH to 3.5, filtering to obtain a solution after preliminary removal of iron, aluminum, and copper; then adding manganese sulfide to the solution after preliminary removal of iron, aluminum, and copper to deeply remove iron and copper, the molar amount of manganese sulfide added being twice the total molar amount of copper and iron in the solution after preliminary removal of iron, aluminum, and copper, filtering to obtain a nickel-cobalt-manganese purified solution;

[0129] (4) Coprecipitation: Detect the concentrations of nickel, cobalt and manganese in the purified liquid, add soluble nickel sulfate, cobalt sulfate and manganese sulfate to the purified liquid to adjust the ratio so that the molar ratio of nickel, cobalt and manganese in the purified liquid is 1:1:1, then add 6 mol / L sodium hydroxide solution and 2 mol / L ammonia solution, maintain the solution pH at 8.5, the reaction temperature is 20°C, and after the reaction is completed, age for 5 hours, filter and dry to obtain a positive electrode material precursor.

[0130] The test results of the positive electrode material precursor obtained by the method for recycling waste lithium-ion battery positive electrode powder according to the present invention are shown in Table 1.

[0131] Example 4

[0132] (1) Hydrogen reduction: waste ternary battery powder containing lithium-ion battery positive electrode material was discharged, disassembled and crushed to obtain 1000 g of positive electrode powder. The positive electrode powder was placed in a hydrogen reduction furnace, and H2 was introduced at a flow rate of 0.8 L / min at a temperature of 600°C for 2 h to obtain a reduced product;

[0133] (2) Water leaching: taking the reduction product of step (1), adding water thereto at a liquid-solid ratio of 20:1, leaching at a temperature of 55°C for 3h, filtering and separating to obtain a lithium-containing leachate and a nickel-cobalt-manganese leach residue, introducing CO2 into the lithium-containing leachate and stirring at a speed of 1000rpm for 1h to precipitate lithium, and obtaining battery-grade lithium carbonate with a purity of 99.7% after refining; adding a mixed extractant of 50vol% tributyl phosphate and 50vol% sulfonated kerosene to the lithium precipitation tail liquid at a volume ratio of 1:1 between the organic phase and the aqueous phase, and retaining the lithium in the lithium precipitation tail liquid in the organic phase by the mixed extractant, while all the remaining substances enter the raffinate; adding a 1mol / L dilute hydrochloric acid stripping agent to the organic phase at a volume ratio of 1:1 between the oil phase and the aqueous phase, stripping the lithium in the organic phase by the stripping agent to obtain a lithium-containing aqueous phase, and then returning to the lithium precipitation process; returning the raffinate obtained by extraction to the water leaching process for reuse; the lithium recovery rate of the whole process is 95.2%;

[0134] (3) acid leaching: adding the nickel-cobalt-manganese leaching residue obtained in step (2) to a 3 mol / L dilute sulfuric acid solution at a liquid-solid ratio of 15:1, then adding H2O2 with a volume fraction of 15%, leaching at 60°C for 3 h to obtain a nickel-cobalt-manganese leaching solution, adding sodium carbonate to the leaching solution to adjust the pH to 4.5, filtering to obtain a solution after preliminary iron removal, aluminum removal, and copper removal; then adding manganese sulfide to the solution after preliminary iron removal, aluminum removal, and copper removal, wherein the molar amount of manganese sulfide added is 1.8 times the total molar amount of copper and iron in the solution after preliminary iron removal, aluminum removal, and copper removal, and filtering to obtain a nickel-cobalt-manganese purified solution;

[0135] (4) Coprecipitation: Detect the concentrations of nickel, cobalt and manganese in the purified liquid, add soluble nickel sulfate, cobalt sulfate and manganese sulfate to the purified liquid to adjust the ratio so that the molar ratio of nickel, cobalt and manganese in the purified liquid is 6:2:2, then add 7 mol / L sodium hydroxide solution and 3 mol / L ammonia solution, maintain the solution pH at 7, and the reaction temperature at 70°C. After the reaction is completed, age for 2 hours, filter and dry to obtain a positive electrode material precursor.

[0136] The test results of the positive electrode material precursor obtained by the method for recycling waste lithium-ion battery positive electrode powder according to the present invention are shown in Table 1.

[0137] Example 5

[0138] The method of Example 1 was followed, except that in step (1), the hydrogen reduction temperature was changed to 800° C., the hydrogen reduction time was changed to 2 h, and the flow rate of the introduced hydrogen was changed to 0.2 L / min; after refining, battery-grade lithium carbonate with a purity of 99.6% was obtained; and the lithium recovery rate of the whole process was 76.3%.

[0139] The results show that a large amount of Li2MnO2 is generated in the hydrogen reduction product, which is insoluble in water, resulting in a low lithium leaching rate during the water leaching process.

[0140] The test results of the positive electrode material precursor obtained by the method for recycling waste lithium-ion battery positive electrode powder according to the present invention are shown in Table 1.

[0141] Example 6

[0142] The method of Example 1 is followed, except that in step (2), the liquid-to-solid ratio of the water immersion is changed to 3:1, the water immersion temperature is changed to 40° C., and the water immersion time is changed to 3 h; after refining, battery-grade lithium carbonate with a purity of 99.7% is obtained; and the lithium recovery rate of the whole process is 85.6%.

[0143] The test results of the positive electrode material precursor obtained by the method for recycling waste lithium-ion battery positive electrode powder according to the present invention are shown in Table 1.

[0144] Example 7

[0145] The method of Example 1 is followed, except that in step (3), sodium carbonate is added to adjust the pH to 2.5; after refining, battery-grade lithium carbonate with a purity of 99.8% is obtained; and the lithium recovery rate of the whole process is 98.2%.

[0146] The test results of the positive electrode material precursor obtained by the method for recycling waste lithium-ion battery positive electrode powder according to the present invention are shown in Table 1.

[0147] Example 8

[0148] The method of Example 1 is followed, except that in step (3), manganese sulfide is replaced by cobalt sulfide, and the molar amount of cobalt sulfide added is 1.8 times the total molar amount of copper and iron in the liquid after preliminary removal of iron, aluminum and copper, and the nickel, cobalt and manganese purified liquid is obtained by filtration.

[0149] The test results of the positive electrode material precursor obtained by the method for recycling waste lithium-ion battery positive electrode powder according to the present invention are shown in Table 1.

[0150] Comparative Example 1

[0151] The method of Example 1 is followed, except that in step (1), hydrogen reduction is replaced by carbon reduction; the purity of the lithium carbonate obtained after purification is 99.6%; and the lithium recovery rate of the whole process is 82.4%.

[0152] The test results of the positive electrode material precursor obtained by the method for recycling waste lithium-ion battery positive electrode powder in this comparative example are shown in Table 1.

[0153] Table 1 Analysis results of cathode material precursors

[0154]

[0155] It can be seen from the results of Table 1 and Examples 1-8 that the positive electrode material precursor obtained by the method for recycling waste lithium-ion battery positive electrode powder provided by the present invention has the main elements of nickel, cobalt and manganese in accordance with the content of nickel, cobalt and manganese in the positive electrode material precursor, and the total impurity content is ≤0.095wt%.

[0156] It can be seen from the results of Table 1 and Examples 1-4 that the lithium recovery rate of the method for recycling waste lithium-ion battery positive electrode powder provided by the present invention is higher than 95%, and battery-grade lithium carbonate with a purity higher than 99.5% is obtained by refining; it can be seen from Table 1, Example 1, and Examples 5-8 that the conditions for hydrogen reduction in Example 5 are not within the preferred range provided by the present invention, and a large amount of Li2MnO2 is generated, which is insoluble in water, resulting in a low lithium leaching rate during the water leaching process; the conditions for water leaching in Example 6 are not within the range provided by the present invention, and the amount of lithium dissolved is slightly reduced, resulting in a slightly lower lithium recovery rate in the whole process; the pH is low during the impurity removal process in Example 7, resulting in some impurities not forming precipitation and separation, resulting in a slightly increased content of impurities in the obtained positive electrode material precursor; Example 8 does not adopt the impurity removal method provided by the present invention, and the impurity content in the obtained positive electrode material precursor is slightly increased; it can be seen from the results of Table 1, Example 1 and Comparative Example 1 that since Comparative Example 1 does not adopt the method provided by the present invention, step (1) adopts carbon reduction, resulting in the generation of lithium aluminum and lithium manganese spinel, low dissolution efficiency, and a low lithium recovery rate in the whole process.

[0157] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for recycling waste lithium batteries, characterized in that: The method comprises the following steps: (1) Hydrogen reduction: pre-treating waste lithium batteries to obtain positive electrode powder, and then subjecting the positive electrode powder to hydrogen reduction to obtain a reduction product; (2) water leaching: leaching the reduced product to obtain a leachate and a leachate residue, wherein the leachate is used to prepare battery-grade lithium carbonate; (3) acid leaching: subjecting the leached residue and the acid leaching agent to oxidative acid leaching to obtain a nickel, cobalt and manganese leachate; (4) Coprecipitation: optionally adding at least one of a soluble nickel salt, a cobalt salt and a manganese salt to the leachate, and then coprecipitating and aging to obtain a lithium battery positive electrode material precursor.

2. The method according to claim 1, wherein In step (1), the pretreatment is to discharge, disassemble and crush the waste lithium batteries to obtain positive electrode powder; Preferably, the reduction product includes lithium compounds, nickel, cobalt, manganese elements and low-valent oxides; Preferably, the temperature of the hydrogen reduction is 400-700° C., preferably 450-550° C.; the time of the hydrogen reduction is 0.5-4 h, preferably 1-2 h; Preferably, in step (1), the flow rate of H2 introduced during hydrogen reduction is 0.2-0.8 L / min, preferably 0.3-0.5 L / min, relative to 1000 g of positive electrode powder.

3. The method according to claim 1 or 2, wherein: The leaching temperature of the water immersion is 20-95°C, preferably 70-90°C; the leaching time of the water immersion is 0.5-4h, preferably 1-2h; Preferably, the liquid-to-solid mass ratio of the water immersion is 4.5-30:1, preferably 5-10:

1.

4. The method according to any one of claims 1 to 3, wherein: In step (2), the obtained leachate is subjected to lithium precipitation to obtain crude lithium carbonate and lithium precipitation tail liquid, and the crude lithium carbonate is refined to obtain battery-grade lithium carbonate; the lithium precipitation tail liquid is subjected to extraction and back extraction, and the obtained lithium-containing aqueous phase is returned to the lithium precipitation process; the raffinate obtained by extraction is returned to the water leaching process for reuse; Preferably, the specific steps of precipitating lithium include: adding carbonate or introducing carbon dioxide, performing carbonation leaching under stirring conditions, and solid-liquid separation to obtain crude lithium carbonate; Preferably, the carbonate is selected from at least one of potassium carbonate, sodium carbonate and sodium bicarbonate; Preferably, the lithium precipitation time is 0.5-4h; Preferably, the stirring speed is 200-600 rpm.

5. The method according to claim 4, wherein The extraction agent used in the extraction is tributyl phosphate-sulfonated kerosene; Preferably, the volume fraction of tributyl phosphate is 40-80%; Preferably, the volume ratio of the oil phase to the water phase in the extraction is 1:5-2:1, preferably 1:4-1:2; Preferably, the stripping agent used in the stripping is selected from at least one of hydrochloric acid, sulfuric acid and nitric acid, preferably hydrochloric acid; Preferably, the concentration of the stripping agent is 1-6 mol / L; Preferably, the volume ratio of the oil phase to the water phase in the stripping is 1:2-4.5:1, preferably 2:1-4:

1.

6. The method according to any one of claims 1 to 5, wherein: The acid leaching agent in step (3) is selected from at least one of sulfuric acid, hydrochloric acid and nitric acid; Preferably, the concentration of the pickling agent is 2-6 mol / L; Preferably, the oxidizing acid leaching uses an oxidizing agent selected from at least one of air, oxygen and hydrogen peroxide; Preferably, the volume fraction of the hydrogen peroxide is 5-20%; Preferably, the liquid-to-solid mass ratio in the oxidizing acid leaching is 4.5-30:1, preferably 5-10:1; Preferably, the leaching temperature of the oxidative acid leaching in step (3) is 20-95° C., preferably 70-90° C.; the leaching time of the oxidative acid leaching is 0.5-4 h, preferably 1-2 h.

7. The method according to any one of claims 1 to 6, wherein: Step (3) further comprises: removing impurities from the obtained nickel-cobalt-manganese leaching solution to obtain a purified solution; Preferably, the specific steps of removing impurities include: adjusting the pH of the obtained leachate to remove aluminum, iron and copper to obtain a purified solution; Preferably, the specific steps of removing impurities include: adjusting the pH of the obtained leachate to perform preliminary removal of aluminum, iron and copper, and then adding manganese sulfide to the obtained solution after preliminary removal of aluminum, iron and copper to perform deep removal of iron and copper to obtain a purified solution; Preferably, the total molar ratio of the manganese sulfide to the copper and iron in the solution after preliminary removal of aluminum, iron and copper is 1.05-2:1; Preferably, the pH of the impurity removal is 3.5-5.

8. The method according to any one of claims 1 to 7, wherein: In step (4), the molar ratios of nickel, cobalt and manganese in the positive electrode material precursor are adjusted to be 1:1:1, 6:2:2 and 8:1:1 by adjusting the amount of soluble nickel salt, cobalt salt and manganese salt added and the conditions of the coprecipitation reaction; Preferably, the salts of the soluble nickel salt, cobalt salt and manganese salt are each independently selected from at least one of sulfate, nitrate and chloride; Preferably, step (4) further comprises adjusting the pH of the leachate by adding alkali solution and ammonia solution; Preferably, the base is a caustic alkali, preferably at least one selected from sodium hydroxide, potassium hydroxide, calcium hydroxide and lithium hydroxide; Preferably, the concentration of the alkali solution is 6-8 mol / L; Preferably, the concentration of the ammonia water is 2-3 mol / L; Preferably, the pH of the coprecipitation reaction is 7-8.5; the temperature of the coprecipitation reaction is 20-75°C, preferably 50-70°C; Preferably, the aging time is 2-5 hours.

9. A battery-grade lithium carbonate, characterized in that The method is prepared by any one of claims 1 to 8.

10. A lithium battery positive electrode material precursor, characterized in that: The method is prepared by any one of claims 1 to 8.

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