Recovery method of metal lithium battery

Abstract

The invention discloses a recovery method of a metal lithium battery, relates to the technical field of lithium battery recovery, and discloses the recovery method of the metal lithium battery, which comprises the following steps: providing a battery waste material containing metal lithium; the method comprises the following steps: mixing battery waste with lithiated powder, heating until metal lithium in the battery waste is in a molten state, and separating to obtain lithium-rich powder; performing acid leaching on the lithium-rich powder to obtain a first lithium-containing solution; adding alkali into the first lithium-containing solution to obtain a second lithium-containing solution; adding sodium carbonate into the second lithium-containing solution to obtain lithium carbonate. The metal lithium battery recycling process is simple and convenient, and the safety is high.

Description

Technical Field

[0001] This application relates to the field of lithium battery recycling technology, and in particular to a method for recycling lithium metal batteries. Background Technology

[0002] With the rapid development of the lithium battery market, lithium metal batteries are gradually becoming a popular choice for next-generation high-energy-density batteries due to their high energy density and low electrode potential. However, the high reactivity of lithium metal also brings significant safety hazards and recycling challenges.

[0003] Currently, the technology for recycling lithium metal anodes is still in the exploratory stage. Lithium metal reacts readily with air or moisture during the recycling process to generate hydrogen, which increases the risk of recycling operations. Furthermore, conventional recycling methods are usually complex and not safe enough.

[0004] The above content is only used to help understand the technical solution of this application and does not represent an admission that the above content is prior art. Summary of the Invention

[0005] The main objective of this application is to provide a method for recycling lithium metal batteries, which is simple and safe.

[0006] To achieve the above objectives, this application proposes a method for recycling lithium metal batteries, the method comprising: Battery waste is provided, wherein the battery waste contains metallic lithium; The battery waste is mixed with lithiizable powder, heated until the metallic lithium in the battery waste is in a molten state, and then separated to obtain lithium-rich powder. The lithium-rich powder is subjected to acid leaching to obtain a first lithium-containing solution; Add alkali to the first lithium-containing solution to obtain a second lithium-containing solution; Lithium carbonate is obtained by adding soda ash to the second lithium-containing solution.

[0007] In one feasible embodiment, the lithiatable powder includes at least one of silicon powder, graphite powder, hard carbon powder, and silicon carbide powder.

[0008] In one feasible embodiment, the amount of the lithiatable powder added is 1.0 to 15 times the amount of metallic lithium in the battery waste, in molar ratio.

[0009] In one feasible embodiment, the temperature at which the lithium metal in the battery waste is heated to a molten state is 190~300°C.

[0010] In one feasible embodiment, the acid used for the acid leaching includes at least one of sulfuric acid, hydrochloric acid, and phosphoric acid; And / or, in molar ratio, the acid:the lithium-rich powder = (3:1)~(10:1); And / or, the leaching temperature of the acid leaching is 80~95℃.

[0011] In a feasible embodiment, the step of adding alkali to the first lithium-containing solution includes: The pH was controlled at 10-13 and the reaction temperature at 80-90℃.

[0012] In one feasible embodiment, the amount of soda ash added is 1.0 to 2.0 times the amount of metallic lithium in the battery waste, in molar ratio. And / or, the reaction temperature after adding soda ash is 60~100 ℃.

[0013] In a feasible embodiment, prior to the step of adding soda ash to the second lithium-containing solution to recover lithium carbonate, the method further includes: Solid-liquid separation yields the first leaching residue after acid leaching and the adjusting residue after adding alkali to the first lithium-containing solution. The first leaching residue and the value-adjusting residue are mixed, and an acid leaching agent is added to obtain a leaching solution and a second leaching residue, wherein the leaching solution contains valuable metals; The second leaching residue is reused as the lithiumable powder.

[0014] In a feasible embodiment, when the positive electrode material of the lithium metal battery is a ternary nickel-cobalt-manganese compound, the acid leaching agent is sulfuric acid; And / or, if the positive electrode material of the lithium metal battery is lithium iron phosphate, the acid leaching agent is phosphoric acid.

[0015] In a feasible embodiment, when the positive electrode material of the lithium metal battery is a ternary nickel-cobalt-manganese compound, the step of adding the acid leaching agent is followed by: A reducing agent is added to the mixture of the first leaching residue and the conditioning residue, wherein the reducing agent includes sodium thiosulfate and / or hydrogen peroxide.

[0016] One or more technical solutions proposed in this application have at least the following technical effects: providing battery waste, wherein the battery waste contains metallic lithium; mixing the battery waste with lithiizable powder, heating until the metallic lithium in the battery waste is in a molten state, separating to obtain lithium-rich powder, the molten lithium will fully contact and react with the surrounding lithiizable powder to form lithium-rich powder, converting the highly active, flammable and explosive metallic lithium into chemically more stable and non-flammable lithium-rich powder; subjecting the lithium-rich powder to acid leaching to obtain a first lithium-containing solution; adding alkali to the first lithium-containing solution to obtain a second lithium-containing solution to remove some impurities in the waste; then adding soda ash to the second lithium-containing solution to obtain lithium carbonate, which can obtain high-purity lithium carbonate. The recycling process of the embodiments of this application is simple and safe, and can directly separate and recover high-purity lithium carbonate. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A schematic flowchart of the method for recycling lithium metal batteries according to this application; Figure 2 This is a schematic flowchart of a more complete embodiment of the lithium metal battery recycling method of this application.

[0020] The purpose, features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0022] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the lithium metal battery recycling method of this application. However, unnecessary details may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0023] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for a specific parameter, it is also expected that ranges of 60~110 and 80~120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this application, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0024] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0025] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0026] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0027] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0028] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0029] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the technical solution of this application is further described below in conjunction with the accompanying drawings and embodiments. However, this application is not limited to the listed embodiments, but should also include any other well-known modifications within the scope of the claims made in this application.

[0030] The term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of this application. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0031] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.

[0032] Among conventional technologies, the recycling techniques for lithium metal batteries are relatively limited and complex. For example, physical dismantling requires strict control of environmental conditions to avoid moisture contact; high-temperature smelting can effectively recover some valuable metals, but it is energy-intensive and may produce harmful gases; hydrometallurgy requires a large amount of chemical reagents, which is costly; at the same time, lithium metal reacts readily with air or moisture during the recycling process to generate hydrogen gas, increasing operational risks.

[0033] This application provides a solution for recycling battery waste containing metallic lithium. The battery waste is mixed with lithiizable powder and heated until the metallic lithium in the waste is molten. After separation, lithium-rich powder is obtained. The molten lithium fully contacts and reacts with the surrounding lithiizable powder to form lithium-rich powder, converting the highly active, flammable, and explosive metallic lithium into a more chemically stable and non-flammable lithium-rich powder. The lithium-rich powder is then acid-leached to obtain a first lithium-containing solution. An alkali is added to the first lithium-containing solution to obtain a second lithium-containing solution, removing some impurities from the waste. Then, soda ash is added to the second lithium-containing solution to recover lithium carbonate, yielding high-purity lithium carbonate. The recycling process in this embodiment involves no violent reactions, is simple and safe, and can directly separate and recover high-purity lithium carbonate. Furthermore, other valuable metals can also be recovered simultaneously with high-purity lithium carbonate, achieving efficient recycling of lithium metal batteries.

[0034] Based on this, embodiments of this application provide a method for recycling lithium metal batteries, referring to... Figure 1 In this embodiment, the method for recycling lithium metal batteries includes: Step S10, providing battery waste, wherein the battery waste contains metallic lithium; In one feasible embodiment, the lithium metal battery can be crushed to obtain battery waste containing lithium metal.

[0035] Lithium metal batteries typically refer to batteries that use lithium metal as the negative electrode. These batteries utilize the efficient ion insertion and extraction capabilities of lithium metal during charging and discharging to store and release energy. Lithium metal batteries have attracted considerable attention due to their high energy density and lightweight design.

[0036] For example, waste batteries are crushed under an inert atmosphere to obtain battery waste containing metallic lithium.

[0037] Step S20: Mix the battery waste with lithiumable powder, heat until the metallic lithium in the battery waste is in a molten state, and then separate to obtain lithium-rich powder; In one feasible embodiment, battery waste is mixed with lithiizable powder, and the lithiizable powder absorbs metallic lithium. The battery waste is heated until the metallic lithium becomes molten, and then the molten metallic lithium is absorbed by the lithiizable powder to obtain lithium-rich powder, which prepares for subsequent lithium extraction and recovery. This is because when metallic lithium is in a molten state, its activity is enhanced, making it easier to interact with the lithiizable powder and thus be absorbed into the interior of the lithiizable powder.

[0038] Battery waste is thoroughly mixed with lithiizable powder, and then the mixture is heated. As the temperature rises, the metallic lithium in the battery waste gradually reaches its melting point (approximately 180.54°C), transforming into a molten state. In this state, the metallic lithium exhibits good fluidity and can fully contact the surrounding lithiizable powder. The lithiizable powder then fixes the molten metallic lithium within its structure through chemical reactions or physical adsorption, ultimately forming lithium-rich powder. Subsequently, the lithium-rich powder is separated from the mixture using appropriate separation methods (such as screening and filtration).

[0039] In one feasible embodiment, the lithium-electrolyzable powder includes at least one of silicon powder, graphite powder, hard carbon powder, and silicon carbide powder.

[0040] Silicon powder possesses a high theoretical specific capacity and can undergo alloying reactions with lithium. Under heating conditions, molten lithium atoms can diffuse into the silicon lattice, forming lithium-silicon alloys (such as Li₄·₄Si), thereby absorbing lithium. This high lithium storage capacity of silicon powder makes it an effective lithium-encapsulating material. The large lithium absorption capacity of silicon powder helps increase the lithium content in lithium-rich powders, providing more raw materials for subsequent lithium recovery.

[0041] Graphite is a layered carbon material, and lithium atoms can intercalate into the interlayers of graphite to form lithium-graphite intercalation compounds (such as LiC6). This intercalation reaction can occur spontaneously under certain temperature and conditions. When metallic lithium is in a molten state, lithium atoms are more likely to intercalate into the graphite interlayers. Graphite has good electrical conductivity and chemical stability, is widely available, and has low cost, making it widely used in the battery field. When used as a lithium-based powder, it is relatively simple to handle and can effectively enrich lithium.

[0042] Hard carbon is a carbon material with a disordered structure containing numerous micropores and defects, which can serve as storage sites for lithium atoms. Molten lithium atoms can fill these micropores and defects, achieving lithium absorption. Hard carbon exhibits good structural stability and strong lithium absorption capacity, and it is not prone to structural collapse during lithium absorption, which helps maintain the stability of lithium-rich powders.

[0043] Silicon carbide powder is a composite material made of silicon and carbon, combining the high specific capacity of silicon with the good conductivity and stability of carbon. During lithium absorption, silicon provides numerous lithium storage sites, while carbon buffers the volume changes of silicon during lithium absorption and improves the material's conductivity. Silicon carbide powder integrates the advantages of both silicon and carbon, achieving high-capacity lithium absorption while maintaining material stability and conductivity, thus contributing to improved performance of lithium-rich powders and the efficiency of subsequent lithium recovery.

[0044] Optionally, the lithium-rich powder is a mixture of cathode black powder separated by multi-stage sorting and the addition of lithium-capable powder.

[0045] Multi-stage sorting is a progressively refined separation process. It doesn't complete the separation task in one step, but rather through multiple sorting steps. Each stage of sorting is tailored to different material characteristics or under different conditions, gradually improving the precision and purity of the separation to effectively separate the target components. In the context of lithium metal battery recycling, multi-stage sorting aims to effectively separate the mixture of cathode black powder and lithiated powder.

[0046] It can be carried out through physical sorting methods, such as screening, magnetic separation, and air separation, as well as chemical sorting.

[0047] Sieving separates particles based on their size. Mixtures are sieved in multiple stages. For example, larger particles are first sieved using a sieve with larger apertures, and then further separated using a sieve with smaller apertures.

[0048] Air separation separates particles based on their different suspension velocities. Wind power agitates particles in a mixture; due to differences in density, shape, and other factors, the suspension velocities and trajectories of the particles vary under the influence of wind. By adjusting the wind speed and direction, and through multiple stages of air separation, separation can be achieved.

[0049] If some components in a mixture have magnetic differences, they can be separated using magnetic separation.

[0050] Chemical sorting refers to the separation of substances in a mixture based on their differences in solubility in different chemical reagents.

[0051] In one feasible embodiment, the amount of lithiatable powder added is 1.0 to 15 times the amount of metallic lithium in the battery waste, based on a molar ratio.

[0052] Optionally, the amount of lithiatable powder added is 1.0 times, 2.0 times, 3.0 times, 4.0 times, 5.0 times, 6.0 times, 7.0 times, 8.0 times, 9.0 times, 10.0 times, 11.0 times, 12.0 times, 13.0 times, 14.0 times, 15.0 times, etc., the molar amount of metallic lithium in the battery waste.

[0053] Optionally, the amount of graphite powder added is 10.0 times the amount of lithium in the battery waste, in molar ratio.

[0054] Optionally, the amount of hard carbon powder added is 15.0 times the amount of lithium in the battery waste, in molar ratio.

[0055] Optionally, the amount of silicon powder added is 1.0 times the amount of lithium in the battery waste, in molar ratio.

[0056] In the reaction between lithiate powder and metallic lithium, the amount of lithiate powder added is crucial to the success of the reaction. The lithiate powder needs sufficient active sites to accommodate and bind lithium from battery waste. Therefore, appropriately increasing the amount of lithiate powder helps improve lithium absorption efficiency, ensuring that as much lithium as possible is captured by the lithiate powder. While excessive lithiate powder addition may further increase lithium absorption, the increase gradually diminishes. This is because as the amount of lithiate powder increases, the diffusion distance of lithium within it becomes longer, limiting the reaction rate. Furthermore, excessive lithiate powder increases the difficulty and cost of subsequent separation and processing, while also causing unnecessary resource waste. Moreover, a suitable amount of lithiate powder added facilitates subsequent separation and recycling processes. When the ratio of lithiate powder to lithium is in the range of 1.0 to 15.0, the resulting lithium-rich powder exhibits good separability in both physical and chemical properties.

[0057] Optionally, by heating the metallic lithium in the battery waste to a molten state, the introduction of other substances and solvents (e.g., organic solvents) is avoided, reducing the number of solid-liquid separation steps, simplifying the operation process, and making it more suitable for industrial-scale preparation. The use of organic solvents to generate organolithides is avoided, as organolithides pose risks of combustion or highly reactive reactions. Organolithides may also form more complex compounds during acid leaching or subsequent lithium-ion precipitation steps, or adsorb onto the surface of lithium carbonate, leading to a decrease in the purity of the final lithium carbonate product. This embodiment, by heating to a molten state, makes the reaction conditions more mild and controllable. Furthermore, the melting step allows for sufficient contact between lithium and the lithiateable powder, potentially improving lithium conversion efficiency. This embodiment does not introduce other organic solvents or added substances, contributing to obtaining a higher purity lithium carbonate product.

[0058] In one feasible implementation, the temperature at which the lithium metal in the battery waste is heated to a molten state is 190~300°C.

[0059] Optionally, the temperature at which the lithium metal in the battery waste is heated to a molten state can be 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, etc.

[0060] Optionally, in the process of recycling lithium metal batteries, heating the battery waste to 190~300℃ aims to separate the lithium metal in a molten state, while avoiding excessive decomposition of other materials or causing safety hazards.

[0061] Step S30: The lithium-rich powder is acid-leached to obtain a first lithium-containing solution; In one feasible embodiment, acid is added and stirred to leach lithium-rich powder, thereby leaching lithium ions and other valuable metal ions, and then separating the solid and liquid to obtain a first lithium-containing solution and a first leaching residue.

[0062] Optionally, the acid used for pickling includes at least one of sulfuric acid, hydrochloric acid, and phosphoric acid.

[0063] Optionally, the hydrogen ion concentration of the leaching agent used for acid leaching can be 0.5 mol / L.

[0064] Optionally, the ratio of acid to lithium-rich powder is (3:1) to (10:1) in molar ratio. Optionally, the ratio of acid to lithium-rich powder can be 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, etc., in molar ratio.

[0065] Optionally, based on the stoichiometry of lithium content and valuable metals (such as Ni, Co, Mn, Fe, etc.) in the powder, excess acid is used to ensure the full leaching of lithium ions and valuable metal ions.

[0066] Optionally, the leaching temperature for acid leaching is 80~95℃.

[0067] Optionally, the leaching temperature for acid leaching can be: 80 ℃, 82 ℃, 84 ℃, 86 ℃, 88 ℃, 90 ℃, 92 ℃, 94 ℃, 95 ℃, etc.

[0068] Optionally, the temperature of the acid leaching process can be controlled within the range of 80-95°C. A suitable temperature helps to increase the rate of the acid leaching reaction and the leaching rate of lithium ions and valuable metal ions. If the temperature is too low, the reaction rate may be slow, and the leaching of lithium ions and valuable metal ions may be incomplete; if the temperature is too high, it may increase energy consumption and may even trigger some side reactions.

[0069] Step S40: Add alkali to the first lithium-containing solution to obtain the second lithium-containing solution.

[0070] In one feasible embodiment, an alkali is added to the first lithium-containing solution to adjust the pH. By adjusting the pH value of the solution by adding alkali, valuable metals such as nickel, cobalt, and manganese are separated from the solution in the form of precipitates such as hydroxides, while lithium ions remain in the solution, thereby obtaining a second lithium-containing solution containing only lithium (or with a relatively higher lithium content), thus achieving the separation of valuable metals and lithium in battery waste.

[0071] In one feasible embodiment, the step of adding alkali to the first lithium-containing solution includes: The pH was controlled at 10-13 and the reaction temperature at 80-90℃.

[0072] Optionally, the pH can be 10, 10.5, 11, 11.5, 12, 12.5, 13, etc. Within the above pH range, valuable metals such as nickel, cobalt, and manganese can be completely precipitated.

[0073] Optionally, the reaction temperature can be 80℃, 82℃, 84℃, 86℃, 88℃, 90℃, etc. A suitable reaction temperature helps to accelerate the precipitation reaction rate, allowing valuable metals to precipitate more quickly, and also facilitates the formation of more easily separable precipitate particles. If the temperature is too low, the precipitation reaction rate may be slow, resulting in incomplete precipitation; if the temperature is too high, it may increase energy consumption and potentially have adverse effects on other components in the solution.

[0074] Optionally, the alkali addition step can remove valuable metal ions from the acid leaching solution, reduce co-precipitation during lithium precipitation, and thus further improve the purity of lithium carbonate.

[0075] Step S50: Add soda ash to the second lithium-containing solution to obtain lithium carbonate.

[0076] In one feasible implementation, after the preceding acid leaching and separation of valuable metals, lithium ions are relatively enriched in the second lithium-containing solution. By adding soda ash (sodium carbonate), a chemical reaction is used to convert the lithium ions into lithium carbonate precipitate, thereby realizing the transformation of lithium element from solution to solid and achieving the purpose of recovering lithium resources. Lithium carbonate is an important lithium compound with wide applications in many fields such as batteries, ceramics, and glass.

[0077] In one feasible embodiment, the amount of soda ash added is 1.0 to 2.0 times the amount of metallic lithium in the battery waste, in molar ratio.

[0078] Optionally, the amount of soda ash added is 1.0 times, 1.2 times, 1.4 times, 1.6 times, 1.8 times, or 2.0 times the amount of lithium metal in the battery waste, based on a molar ratio.

[0079] Lithium carbonate retains some solubility in high-temperature aqueous solutions. Excess soda ash inhibits dissolution through the common ion effect, increasing the precipitation rate. Consequently, residual Ca may remain in the solution. 2+ Mg 2+ Equal to CO3 2- Reactions (such as the formation of CaCO3 and MgCO3) consume additional soda ash.

[0080] Optionally, the reaction temperature after adding soda ash is 60~100 ℃.

[0081] Optionally, the reaction temperature after adding soda ash can be 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃, etc.

[0082] In one feasible embodiment, before step S50, which involves adding soda ash to the second lithium-containing solution to obtain lithium carbonate, the method further includes: Step A10: Solid-liquid separation, yielding the first leaching residue after acid leaching and the conditioning residue after adding alkali to the first lithium-containing solution.

[0083] Two solid-liquid separation operations were performed to obtain the first leaching residue after acid leaching and the conditioning residue after adding alkali to the first lithium-containing solution. In the preceding acid leaching step, the lithium-rich powder reacted with the acid, and some components dissolved into the solution to form the first lithium-containing solution. The undissolved solid material became the first leaching residue, which may contain some unreacted valuable metal compounds. After adding alkali to the first lithium-containing solution, valuable metals such as nickel, cobalt, and manganese precipitated, and the conditioning residue, rich in valuable metals, was obtained through solid-liquid separation. Solid-liquid separation separates the solid and liquid components, preparing for further processing of the conditioning residue.

[0084] Step A20: Mix the first leaching residue and the conditioning residue, add acid leaching agent to obtain leaching solution and second leaching residue, wherein the leaching solution contains valuable metals.

[0085] Both the first leaching residue and the conditioning residue contain a certain amount of valuable metals. After mixing them, they are leached again with acid. The reaction between the acid and the metal compounds dissolves these valuable metals into the solution, forming the leachate. This allows for further extraction of valuable metals from the leaching residue, improving the recovery rate. For example, oxides or hydroxides of metals such as nickel, cobalt, and manganese can react with acid to form the corresponding metal salts, which then enter the solution.

[0086] Step A30: The second leaching residue is recycled as lithium-soluble powder.

[0087] After two acid leaching and alkali treatments, valuable metal ions are extracted from the second leaching residue, yielding insoluble lithium-bearing powder. Reusing this insoluble lithium-bearing powder in the overall recycling process enables its recycling, further improving resource recovery efficiency, reducing waste generation, minimizing environmental impact, and lowering the overall cost of the recycling process.

[0088] In one feasible implementation, when the positive electrode material of the lithium metal battery is a ternary nickel-cobalt-manganese compound, the acid leaching agent is sulfuric acid; Optionally, when the cathode material of the lithium metal battery is lithium iron phosphate, the acid leaching agent is phosphoric acid.

[0089] In one feasible embodiment, the ternary nickel-cobalt-manganese cathode material mainly comprises metallic elements such as nickel, cobalt, manganese, and lithium, which typically exist in the form of oxides or composite oxides. The sulfates formed by the reaction of sulfuric acid with the metals generally have good solubility, which is beneficial for the stable existence of metal ions in solution, facilitating subsequent separation and purification operations.

[0090] Optionally, the concentration of sulfuric acid is 2.5~4 mol / L.

[0091] Optionally, the concentration of sulfuric acid can be 2.5 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L, etc.

[0092] Optionally, the molar ratio of the first leaching residue and the conditioning residue to sulfuric acid is 1:5.

[0093] In one feasible embodiment, lithium iron phosphate is a cathode material containing lithium, iron, and phosphorus, and its structure is relatively stable. Phosphoric acid has good chemical compatibility with the phosphorus element in lithium iron phosphate. During acid leaching, phosphoric acid can react with lithium iron phosphate, promoting the dissolution of metal elements such as lithium and iron, while avoiding the introduction of other impurity ions.

[0094] Optionally, the concentration of phosphoric acid is 2 mol / L.

[0095] Optionally, the molar ratio of the first leaching residue and the conditioning residue to phosphoric acid is 1:4.

[0096] In one feasible embodiment, when the positive electrode material of the lithium metal battery is a ternary nickel-cobalt-manganese compound, the step of adding the acid leaching agent is followed by: A reducing agent is added to the mixture of the first leaching residue and the conditioning residue, wherein the reducing agent includes sodium thiosulfate and / or hydrogen peroxide.

[0097] In a feasible embodiment, in ternary nickel-cobalt-manganese cathode materials, metals such as cobalt and manganese may exist in multiple valence states. Some high-valence metal oxides (such as high-valence oxides of cobalt and manganese) are difficult to dissolve directly under acidic conditions. Adding a reducing agent can reduce these high-valence metals to low-valence states, thereby improving their solubility in acidic solutions, which is beneficial for the subsequent extraction and recovery of these metals. By converting the poorly soluble high-valence metals into easily soluble low-valence metals, the rate of metal dissolution from the leaching residue can be accelerated, the leaching time reduced, the efficiency of the entire recovery process improved, and production costs lowered.

[0098] Sodium thiosulfate has strong reducing properties. In acidic environments, it can undergo redox reactions with high-valence metal oxides. For example, sodium thiosulfate can reduce high-valence cobalt oxides to low-valence cobalt ions, making them dissolve in acidic solutions. During the reaction, the sulfur element in sodium thiosulfate undergoes a valence change, generating corresponding oxidation products.

[0099] Optionally, the amount of sodium thiosulfate added is 0.4 to 0.8 times that of nickel, cobalt, and manganese, in molar ratio.

[0100] Optionally, the amount of sodium thiosulfate added is 0.4 times, 0.5 times, 0.6 times, 0.7 times, or 0.8 times that of nickel, cobalt, and manganese, respectively, based on a molar ratio.

[0101] Optionally, the reaction temperature for adding sodium thiosulfate is 95°C.

[0102] Optionally, the reaction time for adding sodium thiosulfate is 2 hours.

[0103] Hydrogen peroxide is also a commonly used reducing agent. Under acidic conditions, the oxygen anions produced by the decomposition of hydrogen peroxide have strong reducing properties and can reduce high-valence metal ions. Simultaneously, the oxygen produced by the decomposition of hydrogen peroxide can also stir the solution, promoting the dissolution and diffusion of metal ions, further improving the leaching effect.

[0104] Optionally, the amount of hydrogen peroxide added is 1.0 to 2.0 times that of nickel, cobalt, and manganese, in molar ratio.

[0105] Optionally, the amount of hydrogen peroxide added can be 1, 1.2, 1.4, 1.6, 1.8, or 2 times that of nickel, cobalt, and manganese, respectively, based on a molar ratio.

[0106] Optionally, the reaction temperature for adding hydrogen peroxide is 60°C.

[0107] Optionally, the reaction time for adding hydrogen peroxide is 1 hour.

[0108] In this embodiment, battery waste containing metallic lithium is provided. The battery waste is mixed with lithiizable powder and heated until the metallic lithium in the battery waste is molten. After separation, lithium-rich powder is obtained. The molten lithium fully contacts and reacts with the surrounding lithiizable powder to form lithium-rich powder, converting the highly active, flammable, and explosive metallic lithium into a more chemically stable and non-flammable lithium-rich powder. The lithium-rich powder is then acid-leached to obtain a first lithium-containing solution. An alkali is added to the first lithium-containing solution to obtain a second lithium-containing solution, removing some impurities from the waste. Then, soda ash is added to the second lithium-containing solution to obtain lithium carbonate, thus obtaining high-purity lithium carbonate. The recycling process in this embodiment involves no violent reactions, is simple and safe, and can directly separate and recover high-purity lithium carbonate.

[0109] To aid in understanding the above technical solutions, a more complete embodiment of a lithium metal battery recycling method is described below, with reference to... Figure 2 This process involves providing spent lithium-ion batteries, crushing them under an inert atmosphere to obtain lithium-containing battery waste, and providing lithiizable powder. The lithium-ion powder is mixed with the battery waste, and the lithium in the waste is heated to a molten state. The lithiizable powder absorbs the lithium, and after separation, lithium-rich powder is obtained. The lithium-rich powder is then acid-leached to obtain a first lithium-containing solution and a first leaching residue. An alkali is added to the first lithium-containing solution to obtain a second lithium-containing solution and a conditioning residue. Soda ash is added to the second lithium-containing solution to recover lithium carbonate. The first leaching residue and the conditioning residue are mixed, and an acid leaching agent is added for a second leaching to obtain a leachate and a second leaching residue, wherein the leachate contains valuable metals. The third leaching residue is reused as lithiizable powder.

[0110] To enable those skilled in the art to clearly understand the details and operations of the above embodiments of this application, and to demonstrate the significant improvement in the performance of the lithium metal battery recycling method of this application, the above technical solutions are illustrated below through multiple embodiments.

[0111] Example 1 Step 1: Crushing lithium metal batteries under an inert atmosphere to obtain battery waste containing lithium metal, wherein the positive electrode material of this batch of batteries is ternary nickel-cobalt-manganese. Step 2: Add graphite powder to the crushed lithium metal battery material from Step 1; Step 3: Heat to 300℃ to molten lithium metal, while continuously stirring the battery fragments to ensure thorough contact and mixing between the graphite powder and the liquid lithium metal, allowing the graphite to absorb the lithium metal and form Li. X C; Step 4: Perform multi-stage sorting to separate lithium-rich powder; Step 5: Acid leaching is performed on the lithium-rich powder with a 0.5 mol / L sulfuric acid solution. The molar ratio of acid to lithium-rich powder is 1:5. The mixture is stirred at 90°C for 2 hours to obtain the first lithium-containing solution and the first leaching residue. Step 6: Add alkali to the first lithium-containing solution to adjust the pH to 13, react at 90℃ for 1 hour, and then filter to obtain the second lithium-containing solution and pH-adjusting residue; Step 7: Add soda ash to the second lithium-containing solution and react at 95°C for 1 hour to obtain high-purity lithium carbonate precipitate. The amount of soda ash added is 1.2 times that of lithium, in terms of molar ratio. Step 8: Mix the first leaching residue and the conditioning residue, add 3 mol / L sulfuric acid solution, the solid-liquid ratio is 1:5, then add sodium thiosulfate, react at 95℃ for 2 hours to obtain a leachate containing valence metals, then filter and separate. The second leaching residue is returned to step 2. The amount of sodium thiosulfate added is 0.5 times that of nickel, cobalt and manganese, based on the molar ratio.

[0112] Example 2 Step 1: Crushing lithium metal batteries under an inert atmosphere to obtain battery waste containing lithium metal, wherein the positive electrode material of this batch of batteries is lithium iron phosphate; Step 2: Add graphite powder to the crushed lithium metal battery material from Step 1; Step 3: Heat to 300℃ to molten lithium metal, while continuously stirring the battery fragments to ensure thorough contact and mixing between the graphite powder and the liquid lithium metal, allowing the graphite to absorb the lithium metal and form Li. X C; Step 4: Perform multi-stage sorting to separate lithium-rich powder; Step 5: Acid leaching is performed on the lithium-rich powder with a 0.5 mol / L sulfuric acid solution. The molar ratio of acid to lithium-rich powder is 1:4. The mixture is stirred at 90°C for 2 hours to obtain the first lithium-containing solution and the first leaching residue. Step 6: Add alkali to the first lithium-containing solution to adjust the pH to 13, react at 90℃ for 1 hour, and then filter to obtain the second lithium-containing solution and pH-adjusting residue; Step 7: Add soda ash to the second lithium-containing solution and react at 95°C for 1 hour to obtain high-purity lithium carbonate precipitate. The amount of soda ash added is 1.2 times that of lithium, in terms of molar ratio. Step 8: Mix the first leaching residue and the conditioning residue, add 2 mol / L phosphoric acid solution, the solid-liquid ratio is 1:4, react at 60℃ for 1 h to obtain a leaching solution containing valence metals, then filter and separate, and return the second leaching residue to step 2.

[0113] Example 3 Step 1: Crushing lithium metal batteries under an inert atmosphere to obtain battery waste containing lithium metal, wherein the positive electrode material of this batch of batteries is ternary nickel-cobalt-manganese. Step 2: Add graphite powder to the crushed lithium metal battery material from Step 1; Step 3: Heat to 250℃ to molten lithium metal, while continuously stirring the battery fragments to ensure thorough contact and mixing between the graphite powder and the liquid lithium metal, allowing the graphite to absorb the lithium metal and form Li. X C; Step 4: Perform multi-stage sorting to separate lithium-rich powder; Step 5: Acid leaching is performed on the lithium-rich powder with a 0.8 mol / L sulfuric acid solution. The molar ratio of acid to lithium-rich powder is 1:5. The mixture is stirred at 90°C for 2 hours to obtain the first lithium-containing solution and the first leaching residue. Step 6: Add alkali to the first lithium-containing solution to adjust the pH to 13, react at 90℃ for 1 hour, and then filter to obtain the second lithium-containing solution and pH-adjusting residue; Step 7: Add soda ash to the second lithium-containing solution and react at 95°C for 1 hour to obtain high-purity lithium carbonate precipitate. The amount of soda ash added is 1.2 times that of lithium, in terms of molar ratio. Step 8: Mix the first leaching residue and the conditioning residue, add 3 mol / L sulfuric acid solution, the solid-liquid ratio is 1:5, then add sodium thiosulfate, react at 95℃ for 2 hours to obtain a leachate containing valence metals, then filter and separate. The second leaching residue is returned to step 2. The amount of sodium thiosulfate added is 0.5 times that of nickel, cobalt and manganese, based on the molar ratio.

[0114] The lithium recovery rate and lithium salt purity of Examples 1-3 were tested, and the results are shown in Table 1 below: Table 1. Lithium recovery rate and lithium carbonate purity of various lithium metal battery embodiments

[0115] As can be seen, the lithium metal battery recycling method provided in this application can achieve a high lithium recovery rate and lithium carbonate purity.

Claims

1. A method for recycling a metal lithium battery, characterized by, The method comprises: providing battery scrap, wherein the battery scrap contains metallic lithium; mixing the battery scrap with lithiumatable powder, heating to a state where the metallic lithium in the battery scrap is molten, and separating to obtain lithium-rich powder; carrying out acid leaching on the lithium-rich powder to obtain a first lithium-containing solution; adding alkali to the first lithium-containing solution to obtain a second lithium-containing solution; adding soda ash to the second lithium-containing solution to obtain lithium carbonate.

2. The method of recycling a lithium metal battery of claim 1, wherein, The lithiumatable powder comprises at least one of silicon powder, graphite powder, hard carbon powder and silicon-carbon powder.

3. The recovery method of a lithium metal battery according to claim 1 or 2, characterized in that, The lithiumatable powder is added in a molar ratio of 1.0-15 times the amount of metallic lithium in the battery scrap.

4. The method of recycling a lithium metal battery of claim 1, wherein, The temperature in the heating to a state where the metallic lithium in the battery scrap is molten is 190-300°C.

5. The method of recycling a lithium metal battery of claim 1, wherein, The acid used in the acid leaching comprises at least one of sulfuric acid, hydrochloric acid and phosphoric acid; and / or, the acid: the lithium-rich powder = (3:1)-(10:1) in molar ratio; and / or, the leaching temperature in the acid leaching is 80-95°C.

6. The method of recycling a lithium metal battery of claim 1, wherein, The step of adding alkali to the first lithium-containing solution comprises: controlling the pH to be 10-13 and the reaction temperature to be 80-90°C.

7. The method of recycling a lithium metal battery of claim 1, wherein, The amount of soda ash added is in a molar ratio of 1.0-2.0 times the amount of metallic lithium in the battery scrap; and / or, the reaction temperature after the addition of soda ash is 60-100°C.

8. The method of recycling a lithium metal battery of claim 1, wherein, Before the step of adding soda ash to the second lithium-containing solution to obtain lithium carbonate, the method further comprises: solid-liquid separation to obtain first leaching residue after the acid leaching and setting residue after the addition of alkali to the first lithium-containing solution; mixing the first leaching residue and the setting residue, adding an acid leaching agent to obtain a leaching solution and second leaching residue, wherein the leaching solution contains valuable metals; recycling the second leaching residue as the lithiumatable powder.

9. The method of recycling a lithium metal battery of claim 8, wherein, In the case where the positive electrode material of the metallic lithium battery is ternary nickel-cobalt-manganese, the acid leaching agent is sulfuric acid; and / or, in the case where the positive electrode material of the metallic lithium battery is lithium iron phosphate, the acid leaching agent is phosphoric acid.

10. The method of recycling a lithium metal battery of claim 9, wherein, In the case where the positive electrode material of the metallic lithium battery is ternary nickel-cobalt-manganese, the method further comprises, after the step of adding the acid leaching agent: adding a reducing agent to the mixture of the first leaching residue and the setting residue, wherein the reducing agent comprises sodium thiosulfate and / or hydrogen peroxide.

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