Application of contact electrocatalytic material and method for recycling lithium battery electrode material

Abstract

This invention pertains to the field of batteries, specifically designing the application of a contact electrocatalytic material and a method for recycling lithium battery electrode materials based on a contact electrocatalytic process. The contact electrocatalytic material is used to completely or partially replace the reducing agent required in a reaction system that uses acid solution to leach metal elements. The lithium battery electrode material recycling method is as follows: 1. Electrode material recycling. 2. Leachate preparation: Select any solid dielectric material as a catalyst; disperse the catalyst and acid solution evenly according to a preset ratio to obtain a leachate. 3. Target metal leaching: Mix the electrode material powder and the leachate to obtain a reaction system; apply reaction conditions at 40-100℃ that promote catalyst-solution contact or cavitation. 4. Target metal extraction. 5. Catalyst recycling. This invention overcomes the problems of poor economy, low safety, and serious pollution associated with traditional wet recycling processes for lithium battery electrodes.

Description

Technical Field

[0001] This invention belongs to the field of batteries, specifically designing an application of a contact electrocatalytic material and a method for recycling lithium battery electrode materials based on a contact electrocatalytic process. Background Technology

[0002] With the rapid popularization of electronic technology in the fields of communication, transportation, and power, the demand for and production of rechargeable batteries are increasing year by year. Among them, lithium-ion batteries (LiBs), with their high energy density and safety, have become the mainstream rechargeable battery products. Lithium-ion batteries are widely used in electronic products, electric vehicles, and energy storage systems in distributed power stations.

[0003] In recent years, with the increasing public awareness of environmental protection and the continuous improvement of electric vehicle technology, electric vehicles are gradually gaining popularity among users due to their lower carbon dioxide emissions. Lithium-ion batteries are also the most widely used battery type in electric vehicles. Therefore, under the combined conditions of multiple trends, the demand for LiBs continues to grow. The most critical and scarce raw materials for lithium batteries are metals such as lithium, nickel, and cobalt. Increased demand for lithium batteries will lead to companies continuously increasing production and consuming large amounts of lithium, nickel, and cobalt raw materials, which will ultimately lead to the accelerated depletion of limited lithium and cobalt metal resources and increase the production cost of batteries.

[0004] The widespread demand for lithium batteries will also lead to a large increase in the amount of waste lithium batteries. The content of metals such as lithium, nickel, and cobalt in these waste lithium batteries is higher than that in natural ores and salt deposits. Therefore, recycling lithium, nickel, cobalt, and other metal materials from waste batteries can be an effective solution to avoid the depletion of natural resources and rising costs, and has important social and economic significance.

[0005] Currently, there are three main methods for recovering metal elements from lithium batteries: pyrometallurgical, hydrometallurgical, and direct recycling. Pyrometallurgical methods involve high-temperature smelting of battery materials, requiring temperatures exceeding 1000 degrees Celsius, and only yield metal alloys. This method is energy-intensive and produces toxic gases. Direct recycling requires meticulous disassembly of the battery, followed by adding different amounts of precursors based on the different components of the processed lithium battery. This approach is unsuitable for large-scale lithium battery recycling. Hydrometallurgical processes involve solvent leaching of metals from electrode powder and separating the leached elements. Traditional hydrometallurgical processes typically require large amounts of reducing agents, which are non-recyclable consumables. Furthermore, industrial hydrometallurgical processes often use large quantities of inorganic acids such as sulfuric acid, nitric acid, and hydrochloric acid, which may produce toxic and harmful gases such as hydrogen sulfide and nitrogen oxides, posing significant risks to the environment and human health.

[0006] For the reasons mentioned above, developing a greener, more efficient, economical, and safer method for recycling lithium battery electrode materials has become a pressing technical challenge for the industry. Summary of the Invention

[0007] To address the problems of poor economic efficiency, low safety, and severe pollution in existing wet recycling processes for lithium battery electrodes, this invention provides an application of contact electrocatalytic materials and a method for recycling lithium battery electrode materials based on contact electrocatalytic processes.

[0008] This invention is achieved using the following technical solution:

[0009] This invention first provides a novel application of contact electrocatalytic materials, the main contents of which are:

[0010] Select a solid dielectric material with the following properties: a) insoluble in water and hydrophobic. b) carrying a negative charge when in contact with water. c) thermally stable in a temperature range below 100°C. d) does not undergo redox reactions with the selected acid solution.

[0011] The selected solid dielectric material is then used to completely or partially replace the reducing agent required in the reaction system for leaching metal elements with acid solution, and to improve the leaching reaction rate and / or leaching efficiency of the acid solution for metal ions.

[0012] For example, this solid dielectric material can be applied to the leachate in the wet recycling process of lithium battery electrodes to reduce or replace the use of reducing agents such as hydrogen peroxide, sodium thiosulfate, sodium bisulfite, glucose, ascorbic acid, sodium sulfite, and ammonium sulfite in the metal leaching process.

[0013] Based on the aforementioned scheme, the present invention also provides a method for recovering lithium battery electrode materials based on a contact electrocatalysis process, which is used to extract various target metal elements, including cobalt and lithium, from lithium battery electrode materials. This method for recovering lithium battery electrode materials includes the following steps:

[0014] I. Electrode Material Recycling

[0015] The recycled lithium batteries are pretreated to extract the electrode material powder loaded on the surface of the conductive base film.

[0016] 2. Leaching solution configuration

[0017] Choose any solid dielectric material as the catalyst; mix the catalyst with the selected organic acid solution in a preset ratio and disperse evenly to obtain the leachate. The pH value of the prepared leachate is 2.0-6.4, and the catalyst content is 0.5-5 g / L.

[0018] The selected solid dielectric material has the following characteristics: a) it is insoluble in water and hydrophobic; b) it carries a negative charge when it comes into contact with water; c) it has thermal stability in a temperature range below 100℃; and d) it does not undergo redox reactions with the selected organic acids.

[0019] The organic acid solution in the leachate is selected from any one or more organic acids other than oxalic acid.

[0020] III. Target Metal Leaching

[0021] The electrode material powder and the leachate were mixed according to the optimal solid-liquid ratio to obtain the reaction system. The reaction temperature of the reaction system was adjusted to 40-100℃, and reaction conditions that could promote the catalyst to contact and separate from the solution or generate cavitation were applied to the reaction system. The reaction was terminated when the cobalt and lithium elements reached the maximum leaching rate.

[0022] IV. Target Metal Extraction

[0023] The leachate from the previous step was subjected to solid-liquid separation to obtain supernatant A and residue B; and the target metal element was extracted sequentially from supernatant A using a stepwise precipitation method.

[0024] The supernatant A is a mixed solution containing the corresponding ions of various metal elements in the electrode material; the residue B contains the solids in the electrode material that did not participate in the reaction or were generated by the reaction, as well as the selected catalyst.

[0025] V. Catalyst Recycling

[0026] Based on the differences in physicochemical properties between the catalyst and other impurities contained in residue B, any physical or chemical process can be selected to separate the catalyst, and the catalyst can be reused to prepare the required leachate.

[0027] As a further improvement of the present invention, in the electrode material recycling process of step one, the pretreatment steps of the lithium battery include the following steps in sequence: (1) fully discharging the lithium battery. (2) disassembling the lithium battery packaging material to obtain the electrode material. (3) calcining the electrode material at a temperature higher than 300°C. (4) separating the powder material from the calcined product.

[0028] As a further improvement of this invention, in the leachate preparation process of step two, the catalysts that can be selected include organic materials such as FEP (perfluoroethylene propylene), PTFE (polytetrafluoroethylene), PVDF (polyvinylidene fluoride), PI (polyimide), etc., as microparticles; or inorganic materials such as aluminum nitride or silicon oxide microparticles. The particle size of the catalyst microparticles is 30 nm-30 μm.

[0029] Organic acid solutions that can be added to the leachate include any one or more of malic acid, ascorbic acid, citric acid, formic acid, acetic acid, succinic acid, tartaric acid, lactic acid, maleic acid, aspartic acid, and glycine.

[0030] As a further improvement of this invention, in the target metal leaching process of step three, the optimal solid-liquid ratio varies depending on the type of electrode material and the content of the target metal element. The higher the content of the target metal in the electrode material, the smaller the solid-liquid ratio; that is, the larger the amount of leachate used. For a specific type of lithium battery and a specific electrode material, the optimal solid-liquid ratio in the reaction system is determined in advance through experiments.

[0031] In this invention, for a specific electrode material, the optimal solid-liquid ratio determined by the experiment should simultaneously satisfy: (1) the comprehensive leaching rate of each element of the current electrode material powder reaches the optimal level under the same leaching reaction conditions; (2) under the condition of achieving the preset leaching rate, the amount of leaching liquid used for the same amount of electrode material is minimized.

[0032] As a further improvement of the present invention, in the target metal leaching process in step three, the selectable reaction conditions for promoting the contact separation of the catalyst and the solution or generating cavitation include: oscillation, stirring, bubbling, dripping, and ultrasonic cavitation treatment.

[0033] As a further improvement of the present invention, in the fourth step of the target metal extraction process, the steps of extracting cobalt and lithium elements from supernatant A using a stepwise precipitation method are as follows:

[0034] (1) Cobalt element precipitation

[0035] In the next step, a sufficient amount of cobalt ion precipitant is added to the supernatant A separated from the leachate; the reaction proceeds fully to obtain a reaction product containing a cobalt precipitate. The cobalt ion precipitant is selected from oxalic acid or soluble oxalate.

[0036] (2) Cobalt element separation

[0037] The reaction product from the previous step was centrifuged to obtain supernatant C and precipitate D. Precipitate D was washed with water and ethanol and then dried to obtain the desired cobalt oxalate.

[0038] (3) Lithium precipitation

[0039] Add sufficient lithium-ion precipitant to the supernatant C; react fully to obtain a reaction product containing lithium precipitate. The lithium-ion precipitant can be a soluble phosphate or carbonate.

[0040] (4) Lithium element separation

[0041] The reaction product from the previous step is centrifuged to separate the supernatant E and precipitate F. Precipitate E is washed and dried to obtain the desired lithium phosphate or lithium carbonate; supernatant E is used to recover other usable components.

[0042] As a further improvement of the present invention, in the process of lithium precipitation and lithium separation, saturated sodium carbonate is selected as the lithium ion precipitant. Hot saturated sodium carbonate is stirred at 70-100°C for 1-6 hours to obtain white precipitate E. The obtained precipitate E is washed with hot water and then dried.

[0043] As a further improvement of the present invention, in the catalyst recovery process of step five, the catalyst recovery methods include two types: chemical process path and physical process path. The chemical process path uses a specific chemical agent to remove substances other than the catalyst from residue B based on the differences in chemical properties between the catalyst and other impurities; the physical process path separates the desired catalyst from the mixture based on the differences in physical properties between the catalyst and impurities.

[0044] When aluminum nitride or silicon oxide is selected as the catalyst, aqua regia or acid / alkali solutions are used as solvents to remove impurities contained in the catalyst. Alternatively, the catalyst can be separated by vibrating sieving or air classification based on the particle size difference between the catalyst and the solvent.

[0045] When the selected catalyst is FEP, PTFE, PVDF, or PI, the desired catalyst is separated by vibrating sieve or flotation.

[0046] The technical solution provided by this invention has the following beneficial effects:

[0047] This invention applies the contact electrocatalysis effect to chemical reaction processes, utilizing free radicals with reducing properties generated by contact electrocatalysis (CEC) to replace various non-recoverable reducing agents required in chemical reactions. This results in significant technical advantages. This approach holds immense research value and broad commercial prospects.

[0048] Furthermore, this invention provides a specific process scheme for applying the physical mechanism of contact electrocatalysis to the recycling process of lithium battery electrode materials. This scheme uses special inorganic or organic dielectric materials added to the leaching solution of the electrode metal, and then promotes the leaching of the electrode metal by the acid solution through ultrasonic cavitation, resulting in a better extraction effect. This type of dielectric catalyst can replace various reducing agents such as hydrogen peroxide used in conventional acid leaching processes, promoting the conversion of trivalent cobalt ions to divalent cobalt ions through electrons generated by contact electrolysis.

[0049] Specifically, the dielectric material used in this embodiment is not consumed in the lithium battery recycling process; it acts as a catalyst, allowing for recycling and repeated use. This significantly reduces the use of chemical agents in the lithium battery recycling process, demonstrating its green and environmentally friendly nature, effectively lowering process costs, and increasing the economic value of battery recycling. Attached Figure Description

[0050] Figure 1 This is a process flow diagram of a lithium battery electrode material recycling method based on contact electrocatalysis provided in Embodiment 2 of the present invention.

[0051] Figure 2 This is a flowchart of the steps involved in obtaining electrode material powder from the disassembly of a lithium battery in Example 2.

[0052] Figure 3 This is a process flow diagram for the stepwise precipitation method to extract lithium and cobalt.

[0053] Figure 4 The curves show the leaching efficiency of each metal in the lithium cobalt oxide electrode as a function of the amount of leachate used in the experiment.

[0054] Figure 5 The curves show the leaching efficiency of each metal in the ternary lithium electrode as a function of the amount of leachate used in the experiment. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "or / and" as used herein includes any and all combinations of one or more of the associated listed items.

[0057] Example 1

[0058] This embodiment provides a novel application of the present invention for contact electrocatalytic materials, the main content of which is:

[0059] Select a solid dielectric material with the following properties: a) insoluble in water and hydrophobic. b) carrying a negative charge when in contact with water. c) thermally stable in a temperature range below 100°C. d) does not undergo redox reactions with the selected acid solution.

[0060] The selected solid dielectric material is then used to completely or partially replace the reducing agent required in the reaction system for leaching metal elements with acid solution, and to improve the leaching reaction rate and / or leaching efficiency of the acid solution for metal ions.

[0061] For example, this type of solid dielectric material can be applied to the leachate in the wet recycling process of lithium batteries to reduce or replace the use of reducing agents such as hydrogen peroxide, sodium thiosulfate, sodium bisulfite, glucose, ascorbic acid, sodium sulfite, and ammonium sulfite in the metal leaching process.

[0062] In practical applications, selectable catalysts include organic materials such as FEP, PTFE, PVDF, and PI microparticles; or inorganic materials such as aluminum nitride and silicon oxide microparticles. It should be noted that aluminum nitride undergoes partial hydrolysis in solution systems, meaning that this material does not completely satisfy the aforementioned constraint d (not undergoing a redox reaction with the selected acid solution). However, the hydrolysis reaction of aluminum nitride in the reaction system is not vigorous and can produce similar catalytic effects. Its catalytic efficiency is only slightly lower than that of silicon oxide; therefore, in this embodiment, aluminum nitride is still considered as one of the alternative catalyst material options.

[0063] In traditional acid leaching systems for target metals, the reactants include hydrogen ions, acid radicals, a reducing agent, and the target metal element or compound. The reducing agent participates in the redox reaction with the target metal element or compound, increasing the leaching rate and leaching percentage. In this system, because the reducing agent directly participates in the reaction between the metal element or compound, it is continuously consumed throughout the leaching process, and the consumption is substantial.

[0064] In this novel embodiment, a solid dielectric material is introduced into the reaction system. If an action (such as ultrasound, oscillation, or gas injection) is applied to the reaction system, causing high-frequency contact separation between the insoluble solid dielectric material and water molecules in the system, contact electrification occurs between the liquid and solid. During contact electrification, water molecules transfer electrons to the surface of the solid dielectric material. These electrons react with oxygen to generate superoxide radicals; under acidic conditions, the superoxide radicals generate hydrogen peroxide; and the water molecule itself becomes a cation hole, immediately combining with neighboring water molecules to generate hydroxyl radicals. The electrons generated by contact electrification, the superoxide radicals, the hydroxyl radicals, and the hydrogen peroxide participate in the leaching reaction, enhancing the leaching effect.

[0065] In this novel reaction system, the interaction between the solid dielectric material and water molecules generates a "reducing agent"—the same as in traditional systems—which participates in the leaching reaction of elemental metals or compounds. Throughout the reaction, the solid dielectric material itself is not lost and can therefore be considered a "catalyst." In this acidic reaction system, no additional reducing agent is needed; simply maintaining a high-frequency contact and separation between the solid and liquid phases allows for continuous generation of the reducing agent, enabling the redox reaction to occur rapidly and sustainably. Therefore, in this reaction process, the reducing agent in traditional systems can be wholly or partially replaced by a "catalyst," significantly reducing the demand for reducing agents in the acid leaching process of metals. This approach represents a novel, simple, efficient, and green leaching process.

[0066] Example 2

[0067] Based on the scheme in Example 1, this example further provides a method for recovering lithium battery electrode materials based on a contact electrocatalysis process; it is used to extract various target metal elements, including cobalt and lithium, from lithium battery electrode materials. For example... Figure 1 As shown, the method for recycling this type of lithium battery electrode material includes the following steps:

[0068] I. Electrode Material Recycling

[0069] The lithium batteries to be recycled are pretreated to extract the electrode material powder loaded on the surface of the conductive base film aluminum film.

[0070] Lithium-ion batteries are a type of battery that uses lithium metal or lithium alloys as the positive / negative electrode materials and a non-aqueous electrolyte solution. Lithium-ion batteries can be broadly classified into two categories: lithium metal batteries and lithium-ion batteries. Lithium metal batteries typically use manganese dioxide as the positive electrode material, metallic lithium or its alloys as the negative electrode material, and a non-aqueous electrolyte solution. Lithium-ion batteries typically use lithium alloy metal oxides as the positive electrode material, graphite as the negative electrode material, and a non-aqueous electrolyte solution.

[0071] This embodiment primarily recovers lithium, cobalt, nickel, manganese, and other metallic elements from lithium-ion batteries. Therefore, it is necessary to disassemble and separate the electrodes containing these materials from the battery. The aforementioned metallic elements in lithium batteries, either in their elemental or compound form, are mostly adhered to the conductive substrate film via a colloidal process. Therefore, as... Figure 2 As shown, the extraction process of the electrode material is as follows:

[0072] (1) Fully discharge the lithium battery. Residual electrical energy in the lithium battery may pose a risk during disassembly, and may even cause the battery to explode. In this embodiment, a 10% sodium chloride solution is used as the battery, and the electrolyte is used for slow discharge.

[0073] (2) Disassemble the lithium battery packaging material to obtain the electrode material. The disassembly process mainly involves removing the external packaging material of the battery to obtain the internal electrode material. During the disassembly process, it is important to avoid puncturing or impacting the electrode material as much as possible to prevent the battery from exploding or burning.

[0074] (3) The electrode material is subjected to high-temperature calcination at a temperature higher than 500°C. The electrode material is mainly composed of lithium and cobalt target metal materials, organic binders, and conductive base film (aluminum film). Therefore, after high-temperature calcination, the organic binder will carbonize and detach from the conductive base film together with the target metal material.

[0075] (4) Separate the powder material from the calcined product.

[0076] In the calcination product, the metal base film mostly remains intact due to its high melting point, while the coating on the base film has been sintered into a powder. Finally, the calcined product is sieved to remove the conductive base film, thus obtaining the desired electrode material powder.

[0077] 2. Leaching solution configuration

[0078] Choose any solid dielectric material as the catalyst; mix the catalyst with the selected organic acid solution in a preset ratio and disperse evenly to obtain the leachate. The pH value of the prepared leachate is 2.0-6.4, and the catalyst content is 0.5-5 g / L.

[0079] The selected solid dielectric material possesses the following specific characteristics: a) it is insoluble in water and hydrophobic; b) it carries a negative charge when contacted with water; c) it exhibits thermal stability in a temperature range below 100℃; and d) it does not undergo redox reactions with the selected organic acids. Selectable catalysts include microparticles of organic materials such as FEP, PTFE, PVDF, and PI; or microparticles of inorganic materials such as aluminum nitride or silicon oxide. The particle size of the catalyst microparticles is 30 nm–30 μm.

[0080] The organic acid solution in the leachate is selected from any one or more organic acids other than oxalic acid. The organic acid solution includes any one or more of malic acid, ascorbic acid, citric acid, formic acid, acetic acid, succinic acid, tartaric acid, lactic acid, maleic acid, aspartic acid, and glycine. The purpose of using organic acid heating in the leachate in this embodiment is that, compared to most inorganic acids, organic acids can avoid the generation of toxic and harmful gases during the later stages of the leaching reaction, thus improving the green and environmentally friendly attributes of the process. Oxalic acid is excluded from the organic acid selection to avoid the formation of insoluble cobalt oxalate during the leaching stage, resulting in a mixture of cobalt oxalate and reaction residue that is difficult to separate. Based on extensive experiments, citric acid is the most preferred organic acid in this embodiment, as it is inexpensive, has good leaching effect, low toxicity, and excellent overall benefits.

[0081] In particular, the leachate prepared in this embodiment completely abandons the use of traditional reducing agents and instead uses a novel, green and environmentally friendly solid dielectric material as a catalyst.

[0082] III. Target Metal Leaching

[0083] The electrode material powder and the leachate were mixed according to the optimal solid-liquid ratio to obtain the reaction system. The reaction temperature of the reaction system was adjusted to 40-100℃, and reaction conditions that could promote the catalyst to contact and separate from the solution or generate cavitation were applied to the reaction system. The reaction was terminated when the cobalt and lithium elements reached the maximum leaching rate.

[0084] In target metal leaching processes, the optimal solid-liquid ratio varies depending on the type of electrode material and the content of the target metal element. For example, the amount of leachate consumed will differ between lithium cobalt oxide electrode material and ternary lithium electrode material of the same mass. Furthermore, for the same type of electrode, different target metal contents will result in different amounts of leachate used. Generally speaking, the higher the target metal content in the electrode material, the larger the amount of leachate required.

[0085] For a specific type of lithium battery and a specific electrode material, this embodiment pre-determines the optimal solid-liquid ratio in the reaction system through experiments. For a specific electrode material, the optimal solid-liquid ratio determined by experiments should simultaneously satisfy: (1) the comprehensive leaching rate of each element of the current electrode material powder reaches the optimal level under the same leaching reaction conditions; (2) under a fixed dosage, the amount of leaching solution used for the same amount of electrode material is minimized, at most reaching the preset leaching rate.

[0086] In the target metal leaching process, selectable reaction conditions to promote catalyst-solid contact separation or cavitation include: oscillation, stirring, bubbling, dripping, and ultrasonic cavitation treatment, etc. Preferably, cavitation bubbles generated by ultrasonic oscillation induce liquid-solid contact separation, thereby causing contact electrification. The ultrasonic power is preferably 100-300W, and the ultrasonic frequency is preferably 20-200kHz; the ultrasonic treatment time can be controlled to be 1-10h.

[0087] IV. Target Metal Extraction

[0088] The leachate from the previous step was subjected to solid-liquid separation to obtain supernatant A and residue B. The target metal element was then extracted sequentially from supernatant A using a stepwise precipitation method. Supernatant A is a mixed solution containing the corresponding ions of various metal elements in the electrode material; residue B contains unreacted or reacted solids from the electrode material, as well as the selected catalyst.

[0089] During the extraction of the target metal, such as Figure 3As shown, the specific steps for extracting cobalt and lithium from supernatant A using a stepwise precipitation method are as follows:

[0090] (1) Cobalt element precipitation

[0091] In the next step, a sufficient amount of cobalt ion precipitant is added to the supernatant A separated from the leachate; the reaction proceeds fully to obtain a reaction product containing cobalt precipitate, with a reaction time of approximately 20-60 minutes. The cobalt ion precipitant is selected from oxalic acid or soluble oxalate, such as sodium oxalate.

[0092] (2) Cobalt element separation

[0093] The reaction product from the previous step was centrifuged to obtain supernatant C and precipitate D. Precipitate D was washed with water and ethanol and then dried to obtain the desired cobalt oxalate.

[0094] (3) Lithium precipitation

[0095] Add sufficient lithium-ion precipitant to the supernatant C; react fully to obtain a reaction product containing lithium precipitate. The lithium-ion precipitant can be a soluble phosphate or carbonate, such as sodium carbonate or sodium phosphate.

[0096] (4) Lithium element separation

[0097] The reaction product from the previous step is centrifuged to separate the supernatant E and precipitate F. Precipitate E is washed and dried to obtain the desired lithium phosphate or lithium carbonate; supernatant E is used to recover other usable components.

[0098] In particular, in order to improve the yield and purity of lithium, saturated sodium carbonate is preferably used as a lithium ion precipitant in the lithium precipitation and lithium separation process. Hot saturated sodium carbonate is stirred at 70-100°C for 1-6 hours to obtain a white precipitate E. The obtained precipitate E is washed with hot water and then dried.

[0099] V. Catalyst Recycling

[0100] Based on the differences in physicochemical properties between the catalyst and other impurities contained in residue B, any physical or chemical process is selected to separate the catalyst, which is then reused to prepare the desired leachate. Specifically, catalyst recovery methods include two approaches: chemical and physical. The chemical approach primarily utilizes specific chemical agents to remove substances other than the catalyst from residue B based on the differences in chemical properties between the catalyst and other impurities. The physical approach, on the other hand, separates the desired catalyst from the mixture based on the differences in physical properties between the catalyst and impurities.

[0101] For example, when using aluminum nitride or silicon oxide as the catalyst, aqua regia or acid / alkali solutions are used as solvents to remove impurities contained in the catalyst. The reaction temperature of aqua regia is 50-90℃, and a reaction time of 0.5-3 hours can essentially remove impurities other than silicon oxide. The filtered solid is then washed and dried to obtain the desired aluminum nitride or silicon oxide catalyst. Alternatively, if a catalyst product with a specific particle size is selected, such that the particle size of the catalyst is significantly different from the particle size of other components contained in the product, a vibrating sieve method can also be used to separate the catalyst from other components.

[0102] When the selected catalyst is FEP, PTFE, PVDF, or PI, the desired catalyst can be separated using either a vibrating sieve method or a flotation method. The vibrating sieve method separates substances based on their different particle sizes, while the flotation method separates substances based on their density differences using a solvent or solution of a specific density.

[0103] Performance testing experiment

[0104] To verify the effectiveness of the solution in this embodiment, recycled waste ternary lithium batteries and waste lithium cobalt oxide batteries were used as materials to verify and test the electrode recycling method in Example 2. The specific process is as follows:

[0105] 1. Dismantling of used batteries

[0106] In this experiment, 10% sodium chloride was used as the electrolyte to impregnate the discharged batteries, further releasing any residual charge inside. The fully discharged batteries were then dried in a 60℃ oven for 24 hours. The lithium batteries were then manually disassembled to obtain the positive electrode material. This positive electrode material was cut into small pieces and placed in a crucible, which was then placed in a muffle furnace for calcination. The calcination temperature was set at 500℃, and the calcination time was set at 30 minutes. The heating rate of the muffle furnace was set at 5℃ / min. After the temperature dropped to room temperature, the batteries were removed. At this point, the material on the electrode material substrate had detached, and after simple processing, the desired lithium nickel cobalt manganese oxide (LiNi) could be collected. 1 / 3Co 1 / 3 Mn 1 / 3 O2) electrode powder and lithium cobalt oxide electrode powder. The collected powder, in addition to lithium nickel cobalt manganese oxide or lithium cobalt oxide, also includes carbonized products of organic binders and other components in the electrode material after calcination.

[0107] 2. Target metal leaching

[0108] (1) In this experimental design, silica (SiO2) dielectric powder with a diameter of 2 μm is preferred as the catalyst. 80 mg of silica was added to 40 mL of 0.2 mol / L citric acid solution and stirred at room temperature for 30 min to ensure uniform dispersion and obtain a leachate. Then, different masses of pretreated lithium cobalt oxide electrode powder were weighed according to the solid-liquid ratio (g / L) of electrode powder to leachate of 4, 6, 8, 10, and 12 and added to beakers. The beakers were then sealed to form the different test sample solutions required. The beakers containing each test sample solution were then placed in an ultrasonic machine at 70 °C and 120 W for 6 h. The products after ultrasonic reaction were then centrifuged to obtain the supernatant.

[0109] The leaching efficiencies of lithium and cobalt in the supernatant after the reaction of each test sample were measured using inductively coupled plasma optical emission spectrometry (ICP-OES). The statistical data are shown in Table 1 below, and plotted based on the statistical data. Figure 4 The graph shows the line graph of the leaching efficiency of each metal as a function of the amount of leachate used.

[0110] Table 1: Statistical data on the leaching efficiency of lithium cobalt oxide as a function of the solid-liquid ratio in the reaction system

[0111] Group Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Solid-liquid ratio (g / L) 4 6 8 10 12 Lithium leaching rate (%) 53.65 78.39 91.67 95.21 94.44 Cobalt leaching rate (%) 36.68 68.38 69.19 80.92 79.58

[0112] Analysis Table 1 and Figure 4 The data shows that within the solid-liquid ratio range of 2–10 g / L, the leaching efficiency of Co and Li exhibits a trend of first increasing and then decreasing. Furthermore, the leaching efficiency of Li and Co is highest at a solid-liquid ratio of 10 g / L, reaching 95.21% and 80.92%, respectively. Therefore, 10 g / L is the optimal solid-liquid ratio for each sample material in this test experiment.

[0113] Further analysis of the data in the figure reveals that the reason for the initial increase followed by a decrease in leaching efficiency is that the solid-liquid ratio primarily affects the contact area between the liquid and the particles. A smaller solid-liquid ratio means a larger contact area between the particles and the acid solution, allowing the leaching reaction to proceed more fully. However, as the solid-liquid ratio increases, the proportion of electrode material powder in the solution also increases. This reduces the H+ concentration gradient between the solid-liquid interface and the solution, resulting in insufficient citric acid and catalytically generated H2O2 in the reaction system to adequately promote the conversion of metal ions, leading to a decrease in leaching efficiency.

[0114] (2) In this experimental design, silica (SiO2) dielectric powder with a diameter of 2 μm is preferred as the catalyst. 80 mg of silica was added to 40 mL of 0.2 mol / L citric acid solution and stirred at room temperature for 30 min to ensure uniform dispersion and obtain a leachate. Then, different masses of pretreated lithium nickel cobalt manganese oxide electrode powder were weighed according to solid-liquid ratios (g / L) of 8, 10, 12, and 14 and added to beakers. The beakers were then sealed to form the different test sample solutions required. The beakers containing each test sample solution were then placed in an ultrasonic machine at 70 °C and 120 W for 6 h. The products after ultrasonic reaction were then centrifuged to obtain the supernatant.

[0115] The leaching efficiencies of lithium and cobalt in the supernatant after the reaction of each test sample were measured using inductively coupled plasma optical emission spectrometry (ICP-OES). The statistical data are shown in Table 2 below, and plotted based on the statistical data. Figure 5 The graph shows the line graph of the leaching efficiency of each metal as a function of the amount of leachate used.

[0116] Table 2: Statistical data on the leaching efficiency of ternary lithium as a function of the solid-liquid ratio of the reaction system

[0117] Group Sample 6 Sample 7 Sample 8 Sample 9 Solid-liquid ratio (g / L) 8 10 12 14 Lithium leaching rate (%) 62.70 94.56 69.84 73.41 Nickel leaching rate (%) 76.57 96.62 81.14 86.33 Manganese leaching rate (%) 68.67 96.54 74.70 79.14 Cobalt leaching rate (%) 83.77 98.39 87.46 92.98

[0118] Analysis shows that when the solid-liquid ratio of the leachate to the electrode powder in this experiment is increased to 10, the leaching efficiency of lithium, nickel, manganese, and cobalt reaches its highest level, at 94.56%, 96.62%, 96.54%, and 98.39%, respectively. This indicates that 10 is also the optimal solid-liquid ratio of the leachate in this embodiment during the ternary lithium electrode recycling process.

[0119] During the ultrasonic leaching of the target metal, cavitation bubbles collapse to generate microjets, inducing contact electrification between the liquid and solid. Water molecules transfer electrons to the silica surface, where these electrons react with oxygen to generate superoxide radicals. Under acidic conditions, these superoxide radicals generate hydrogen peroxide, and the water molecule itself becomes a cation hole, immediately combining with neighboring water molecules to generate hydroxyl radicals. Throughout the reaction system, the electrons generated by contact electrification, superoxide radicals, hydroxyl radicals, and hydrogen peroxide all participate in the leaching reaction of the target metal, enhancing the leaching effect.

[0120] 3. Target metal purification and catalyst recovery

[0121] In this experiment, sample 4 was further centrifuged at 10,000 r / min for 10 min to obtain supernatant A and residue B. Supernatant A was used to purify metallic lithium and metallic cobalt. Residue B was used to recover the catalyst silica.

[0122] 700 mg of sodium oxalate was added to supernatant A, and the mixture was reacted at room temperature for 50 min. Then, it was centrifuged at 10000 r / min for 5 min to obtain precipitate D and supernatant C. Precipitate D was then washed three times each with ultrapure water and anhydrous ethanol to obtain CoC₂O₄·2H₂O. Hot saturated sodium carbonate was slowly added to supernatant C, and the mixture was reacted at 95 °C for 3 h. Subsequently, the mixture was centrifuged to obtain precipitate F, which was washed six times with hot water to obtain Li₂CO₃.

[0123] Residue B was added to 30 mL of aqua regia and stirred at 70 °C for 1 h. Then, it was centrifuged at 10000 r / min for 5 min. The resulting precipitate was washed three times with water and ethanol, respectively, and centrifuged again to obtain the SiO2 catalyst used in the leaching reaction. The silica catalyst can be recycled and reused in the leaching reaction.

[0124] Based on the above embodiments and test experiments, it is evident that this invention effectively promotes the metal leaching reaction in lithium battery electrode powder through contact electrocatalysis caused by the solid-liquid contact electrification physical mechanism, replacing the reducing agent in the acid leaching process. In this scheme, the catalyst participating in the reaction can be repeatedly recycled and reused, demonstrating the economic efficiency of the process. The process significantly reduces the use of chemical reagents, reflecting its green and environmentally friendly attributes.

[0125] The technical features of the embodiments described above can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification.

[0126] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A method for recovering lithium battery electrode materials based on a contact electrocatalysis process, used to extract various target metal elements, including cobalt and lithium, from lithium battery electrode materials, characterized in that... The method for recycling lithium battery electrode materials includes the following steps: I. Electrode Material Recycling Pre-treatment is performed on the lithium batteries to be recycled to extract the electrode material powder loaded on the surface of the conductive base film; 2. Leaching solution configuration Choose any solid dielectric material as a catalyst; mix the catalyst with the selected organic acid solution in a preset ratio and disperse evenly to obtain a leachate; the pH value of the leachate is 2.0-6.4, and the catalyst content is 0.5~5 g / L; The selected solid dielectric material has the following characteristics: a) it is insoluble in water and hydrophobic; b) it carries a negative charge when it comes into contact with water; c) it has thermal stability in a temperature range below 100℃; d) it does not undergo redox reactions with the selected organic acids. The organic acid solution in the leachate shall be any one or more organic acids other than oxalic acid; III. Target Metal Leaching The electrode material powder and the leachate were mixed according to the optimal solid-liquid ratio to obtain the reaction system. The reaction temperature of the reaction system was adjusted to 40-100℃, and reaction conditions that could promote the contact and separation of the catalyst with the solution or generate cavitation were applied to the reaction system. The reaction was terminated when the cobalt and lithium elements reached the maximum leaching rate. IV. Target Metal Extraction The leachate from the previous step was subjected to solid-liquid separation to obtain supernatant A and residue B; and the target metal element was extracted sequentially from supernatant A using a stepwise precipitation method. The supernatant A is a mixed solution containing ions corresponding to various metal elements in the electrode material; the residue B contains solids in the electrode material that did not participate in the reaction or were generated by the reaction, as well as the selected catalyst. V. Catalyst Recycling Based on the differences in physicochemical properties between the catalyst and other impurities contained in residue B, any physical or chemical process can be selected to separate the catalyst, and the catalyst can be reused to prepare the required leachate.

2. The method for recycling lithium battery electrode materials based on contact electrocatalysis as described in claim 1, characterized in that: In the electrode material recycling process of step one, the pretreatment steps of lithium battery include: (1) fully discharging the lithium battery; (2) disassembling the lithium battery packaging material to obtain the electrode material; (3) calcining the electrode material at a temperature higher than 300°C; and (4) separating the powder material from the calcined product.

3. The method for recycling lithium battery electrode materials based on contact electrocatalysis as described in claim 1, characterized in that: In the process of preparing the leachate in step two, the catalysts that can be selected include organic materials such as FEP, PTFE, PVDF, and PI microparticles; or inorganic materials such as aluminum nitride and silicon oxide microparticles; wherein the particle size of the catalyst microparticles is 30nm-30nm. Organic acid solutions that can be added to the leachate include any one or more of malic acid, ascorbic acid, citric acid, formic acid, acetic acid, succinic acid, tartaric acid, lactic acid, maleic acid, aspartic acid, and glycine.

4. The method for recycling lithium battery electrode materials based on contact electrocatalysis as described in claim 1, characterized in that: In the target metal leaching process in step three, the optimal solid-liquid ratio varies depending on the type of electrode material and the content of the target metal element. The higher the content of the target metal in the electrode material, the smaller the solid-liquid ratio. For a specific type of lithium battery and a specific electrode material, the optimal solid-liquid ratio in the reaction system is determined in advance through experiments.

5. The lithium battery electrode material recycling method based on contact electrocatalysis as described in claim 4, characterized in that: For a specific electrode material, the optimal solid-liquid ratio determined by the experiment should simultaneously satisfy: (1) the comprehensive leaching rate of each element of the current electrode material powder reaches the best under the same leaching reaction conditions; (2) under the condition of achieving the preset leaching rate, the amount of leaching liquid used for the same amount of electrode material is minimized.

6. The method for recycling lithium battery electrode materials based on contact electrocatalysis as described in claim 1, characterized in that: In the target metal leaching process in step three, selectable reaction conditions that promote catalyst-solution contact separation or cavitation include: oscillation, stirring, bubbling, dripping, and ultrasonic cavitation treatment.

7. The method for recycling lithium battery electrode materials based on contact electrocatalysis as described in claim 1, characterized in that: In step four, during the target metal extraction process, the specific steps for extracting cobalt and lithium from supernatant A using a stepwise precipitation method are as follows: (1) Cobalt element precipitation In the next step, a sufficient amount of cobalt ion precipitant is added to the supernatant A separated from the leachate; the reaction is carried out to obtain a reaction product containing cobalt element precipitate; wherein, the cobalt ion precipitant is selected from oxalic acid or soluble oxalate; (2) Separation of cobalt element The reaction product from the previous step was centrifuged to obtain supernatant C and precipitate D. After washing precipitate D with water and ethanol and drying it, the desired cobalt oxalate was obtained. (3) Lithium precipitation Sufficient lithium-ion precipitant is added to the supernatant C; the reaction is carried out to obtain a reaction product containing lithium precipitate; wherein the lithium-ion precipitant is selected from soluble phosphate or carbonate. (4) Lithium element separation The reaction product from the previous step is centrifuged to separate the supernatant E and the precipitate F. The precipitate E is washed and dried to obtain the desired lithium phosphate or lithium carbonate. The supernatant E is used to recover other usable components.

8. The method for recycling lithium battery electrode materials based on contact electrocatalysis as described in claim 7, characterized in that: In the lithium precipitation and lithium separation process, saturated sodium carbonate is selected as the lithium ion precipitant. Hot saturated sodium carbonate is stirred at 70~100 ℃ for 1~6 h to obtain white precipitate E. The obtained precipitate E is washed with hot water and then dried.

9. The method for recycling lithium battery electrode materials based on contact electrocatalysis as described in claim 1, characterized in that: In the catalyst recycling process in step five, the catalyst recycling methods include two types: chemical process path and physical process path. The chemical process path uses a specific chemical agent to remove substances other than the catalyst from residue B based on the differences in chemical properties between the catalyst and other impurities. The physical process path separates the required catalyst from the mixture based on the differences in physical properties between the catalyst and impurities. When the catalyst selected is aluminum nitride or silicon oxide, aqua regia or acid / alkali solution is used as a solvent to remove impurities contained in the catalyst; or the catalyst is separated by vibrating sieve or air classification according to the particle size difference between the catalyst and the solvent. When the selected catalyst is FEP, PTFE, PVDF, or PI, the desired catalyst is separated by vibrating sieve or flotation.

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