A method for recycling lithium cobalt oxide battery cathode material based on supercritical hydrothermal oxidation

Abstract

The application provides a lithium cobaltate battery positive electrode material recycling method based on supercritical hydrothermal oxidation, which comprises the following steps: firstly, mixing the positive electrode sheet of the lithium cobaltate battery to be recycled with an oxidizing agent and deionized water, and performing a hydrothermal oxidation reaction in a supercritical state; after the reaction is completed, filtering to obtain filter residue; then, using an organic acid liquid containing a reducing agent to perform acid leaching on the filter residue, adding an aluminum ion precipitant to the acid leaching liquid, and after the precipitation is completed, filtering to obtain an aluminum-removed filtrate; finally, adding lithium salt, a surfactant and a complexing agent to the aluminum-removed filtrate, and after the mixed solution is evaporated, dried and calcined, lithium cobaltate powder is obtained. The method uses supercritical hydrothermal oxidation to treat the binder and conductive additive in the positive electrode sheet, is fast and efficient, and is environmentally friendly; in addition, in the subsequent ion recovery process, a sol-gel method is used to directly regenerate lithium cobaltate material, so that lithium and cobalt are recycled and lithium cobaltate material is generated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery recycling, and particularly relates to a lithium cobalt oxide battery positive electrode material recycling method based on supercritical hydrothermal oxidation. BACKGROUND

[0002] Lithium ion batteries with lithium cobalt oxide as the positive electrode material are widely used in the consumer electronics industry, which increases the pressure of waste battery recycling and the demand for lithium, cobalt and other metals. When cobalt is in the natural environment, it may be converted into compounds that harm the environment. Therefore, recycling lithium, cobalt and other high-value metal materials in lithium ion batteries can not only avoid environmental pollution caused by waste, but also reduce the pressure of mining of high-value mineral elements such as lithium and cobalt, and bring considerable economic benefits.

[0003] On the lithium ion battery positive electrode sheet, the positive electrode active material and acetylene black are coated on the aluminum foil by the binder. The key to separating the positive electrode sheet and the positive electrode active material lies in removing the binder that plays a bonding role. In the pyrometallurgical process, the removal of the binder is mainly through a high-temperature process, which uses high temperature to decompose the binder and at the same time generates harmful gas containing fluorine and emits it to the environment. In the hydrometallurgical process, the binder is usually dissolved by using an organic solvent, and the dissolution process needs to use an expensive organic solvent that is harmful to the environment, and the dissolution process usually needs to consume a long time.

[0004] In addition, when valuable metal ions in the positive electrode active material are recycled, many processes use extraction to extract valuable metal ions in sequence. The extraction process needs to use an extraction agent that is harmful to the environment, and at the same time, complex operations are carried out, which increases the recycling cost and brings the risk of damaging the environment. SUMMARY

[0005] The present application provides a lithium cobalt oxide battery positive electrode material recycling method based on supercritical hydrothermal oxidation, which solves the defects of complex recycling process, high cost and high environmental pollution risk in the prior art, and realizes efficient recycling of lithium cobalt oxide battery positive electrode material.

[0006] The present application provides a lithium cobalt oxide battery positive electrode material recycling method based on supercritical hydrothermal oxidation, which includes:

[0007] Mixing the positive electrode sheet of the lithium cobalt oxide battery to be recycled with an oxidizing agent and deionized water, and carrying out a hydrothermal oxidation reaction under a supercritical state, and after the reaction is complete, carrying out solid-liquid separation to obtain a hydrothermal filtrate and a filter residue;

[0008] Acid leaching the filter residue with an organic acid solution containing a reducing agent, adding an aluminum ion precipitant to the acid leaching solution, and after the precipitation is complete, carrying out solid-liquid separation to obtain an aluminum-containing solid product and an aluminum-removed filtrate;

[0009] Lithium salt, surfactant and complexing agent are added in the aluminum-removed filtrate to adjust the molar ratio of lithium ions and cobalt ions in the solution and the pH value, and after the mixed solution is evaporated, dried and calcined, lithium cobaltate powder is obtained.

[0010] The application further provides a lithium cobaltate battery positive electrode material recovery method based on supercritical hydrothermal oxidation.

[0011] Water-soluble carbonate is added in the hydrothermal filtrate to precipitate lithium ions, and lithium carbonate is obtained through filtration.

[0012] The application further provides a lithium cobaltate battery positive electrode material recovery method based on supercritical hydrothermal oxidation.

[0013] The application further provides a lithium cobaltate battery positive electrode material recovery method based on supercritical hydrothermal oxidation.

[0014] The application further provides a lithium cobaltate battery positive electrode material recovery method based on supercritical hydrothermal oxidation.

[0015] The application further provides a lithium cobaltate battery positive electrode material recovery method based on supercritical hydrothermal oxidation.

[0016] The application further provides a lithium cobaltate battery positive electrode material recovery method based on supercritical hydrothermal oxidation.

[0017] The application further provides a lithium cobaltate battery positive electrode material recovery method based on supercritical hydrothermal oxidation.

[0018] The application further provides a lithium cobaltate battery positive electrode material recovery method based on supercritical hydrothermal oxidation.

[0019] The mixed solution is evaporated to remove water until a gel is formed, the gel is further dried, the dried solid product is ground into a powder, and then calcination is performed in air.

[0020] According to the lithium cobalt oxide battery cathode material recycling method based on supercritical hydrothermal oxidation provided by the application, the water removal process is performed at a temperature of 60-95 DEG C; the drying process is performed at a temperature of 105-150 DEG C; and the calcination process in air includes two-stage calcination, wherein the first-stage calcination is performed at a temperature of 300-500 DEG C for 3-5 hours, and the second-stage calcination is performed at a temperature of 600-900 DEG C for 6-10 hours.

[0021] According to the lithium cobalt oxide battery cathode material recycling method based on supercritical hydrothermal oxidation provided by the application, the oxidizing agent is one or more of hydrogen peroxide, oxygen, potassium permanganate, ammonium persulfate, sodium percarbonate, sodium peroxide, potassium peroxide, calcium peroxide and lithium peroxide.

[0022] The reducing agent is one or more of hydrogen peroxide, ascorbic acid, formaldehyde, glucose, carbon monoxide and hydrogen.

[0023] The organic acid solution is one or more of citric acid, ascorbic acid, oxalic acid, formic acid, acetic acid, succinic acid and tartaric acid.

[0024] The aluminum ion precipitant is lithium hydroxide and ammonia water.

[0025] The lithium salt is one or more of lithium acetate, lithium carbonate, lithium nitrate, lithium hydroxide, lithium oxalate and lithium acetate.

[0026] The surfactant is one or more of ethylene glycol, dodecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide and polyethylene glycol.

[0027] The complexing agent is ammonia water.

[0028] This invention provides a method for recovering lithium cobalt oxide battery cathode materials based on supercritical hydrothermal oxidation. The method involves oxidizing and decomposing the binders and conductive additives on the lithium cobalt oxide battery cathode sheet using supercritical water containing an oxidant, thus separating the cathode material from the aluminum foil substrate. Then, the filter residue is leached with an organic acid solution containing a reducing agent to leach cobalt from the cathode material. Simultaneously, an aluminum ion precipitant is used to separate aluminum-containing solid products, achieving aluminum recovery. Finally, the leachated cobalt is resynthesized into lithium cobalt oxide cathode material using a sol-gel method, achieving the recovery and regeneration of lithium cobalt oxide. This method uses supercritical hydrothermal oxidation to treat the binders and conductive additives in the cathode sheet, eliminating the need for toxic and expensive organic solvents and achieving zero emissions of toxic gases. It can quickly and effectively remove binders and conductive additives, is highly efficient, and environmentally friendly. Furthermore, in the subsequent ion recovery process, the sol-gel method is used to directly regenerate the lithium cobalt oxide material, achieving both cobalt recovery and lithium cobalt oxide material generation. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0030] Figure 1 This is a schematic flowchart of the method for recycling lithium cobalt oxide battery cathode materials based on supercritical hydrothermal oxidation provided by the present invention.

[0031] Figure 2 This is an X-ray diffraction analysis image of the regenerated lithium cobalt oxide produced in an embodiment of the present invention. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. 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.

[0033] like Figure 1 As shown in the figure, an embodiment of the present invention provides a method for recovering lithium cobalt oxide battery cathode material based on supercritical hydrothermal oxidation, comprising:

[0034] The step S100 comprises mixing the positive electrode sheet of the lithium cobalt oxide battery to be recycled with an oxidizing agent and deionized water, performing a hydrothermal oxidation reaction in a supercritical state, and performing solid-liquid separation on the hydrothermal solution after the reaction to obtain a hydrothermal filtrate and a filter residue.

[0035] Specifically, the positive electrode sheet of the lithium cobalt oxide battery to be recycled generally uses an aluminum foil as a substrate, and is uniformly coated with a positive electrode material on both sides. The positive electrode material comprises a certain proportion of lithium cobalt oxide, a conductive additive, and a binder. The conductive additive mainly comprises acetylene black, graphite, etc., and the binder is mainly polyvinylidene fluoride (PVDF).

[0036] The addition amount of the oxidizing agent is 1 mol / L ~ 12 mol / L. In some specific embodiments, the oxidizing agent can be a mixture of one or more of hydrogen peroxide, oxygen, potassium permanganate, ammonium persulfate, sodium percarbonate, sodium peroxide, potassium peroxide, calcium peroxide, and lithium peroxide. The oxidizing agent can be configured into an aqueous solution with deionized water, and if it is a gaseous oxidizing agent, it can be directly introduced into the hydrothermal reactor.

[0037] The solid-liquid ratio of the positive electrode sheet and the aqueous solution added in the hydrothermal reactor can be in the range of 1 g / L ~ 100 g / L, and the filling degree of the hydrothermal reactor can be 30% ~ 60%. By heating and pressurizing the hydrothermal reactor, the oxidizing agent aqueous solution system inside the hydrothermal reactor is in a high-temperature and high-pressure supercritical state above the critical point, thereby realizing the hydrothermal oxidation of the binder and the conductive additive. The oxidation products are carbon dioxide, water, hydrofluoric acid, and salt compounds, and no toxic waste gas is discharged. Since the binder is oxidized and decomposed, the positive electrode material can be separated from the aluminum foil substrate, and at the same time, the lithium cobalt oxide in the positive electrode material is partially or completely reduced to cobalt monoxide and / or metallic cobalt, and the oxide of carbon is generated. In addition, under the supercritical state, the solution in the hydrothermal reactor has very strong reactivity, so the remaining carbon can be almost completely oxidized, and the carbon removal can be completely achieved without additional carbon removal in the subsequent process. In some specific embodiments, the temperature of the hydrothermal oxidation reaction is 380℃ ~ 600℃, the pressure is 24 MPa ~ 40 MPa, and the time is 5 min ~ 200 min.

[0038] After the hydrothermal oxidation reaction is completed, the hydrothermal reactor is cooled and depressurized, and the reaction product is taken out, and then the reaction product is subjected to solid-liquid separation and washing, and the hydrothermal filtrate and the filter residue are collected respectively. The filter residue mainly contains aluminum and aluminum oxide / hydroxide, cobalt oxide, etc. Under the supercritical state, the rate of the hydrothermal oxidation reaction is improved, the time required for complete reaction is correspondingly reduced, and the removal efficiency and effect of the binder and the conductive additive are improved.

[0039] Step S200, the filter residue is subjected to acid leaching with an organic acid solution containing a reducing agent, an aluminum ion precipitant is added to the acid leaching solution, and solid-liquid separation is performed again to obtain an aluminum-containing solid product and an aluminum-removed filtrate.

[0040] Specifically, the amount of the reducing agent added can be 0.1 mol / L to 4 mol / L, and the concentration of the organic acid solution can be 0.1 mol / L to 5 mol / L. In some specific embodiments, the reducing agent can be one or more of hydrogen peroxide, ascorbic acid, formaldehyde, glucose, carbon monoxide, and hydrogen; and the organic acid solution can be one or more of citric acid, ascorbic acid, oxalic acid, formic acid, acetic acid, succinic acid, and tartaric acid. The solid-liquid ratio of the filter residue to the acid leaching solution can be in the range of 1 g / L to 200 g / L. By adding the reducing agent in an acidic system, cobalt and lithium are leached into the aqueous solution together.

[0041] After the acid leaching is completed, an aluminum ion precipitant is added to the acid leaching solution to remove aluminum ions in the acid leaching solution. The aluminum ion precipitant is mainly an alkaline reagent, such as lithium hydroxide and ammonia water. After the aluminum ions are completely precipitated by adjusting the pH value of the acid leaching solution to 3 to 6, the acid leaching solution is subjected to solid-liquid separation to obtain an aluminum-removed filtrate and an aluminum-containing solid product, and the aluminum element is recovered in the form of aluminum and aluminum hydroxide.

[0042] Step S300, lithium salt, surfactant, and complexing agent are added to the aluminum-removed filtrate to adjust the molar ratio of lithium ions to cobalt ions and the pH value of the solution. After the mixed solution is subjected to evaporation drying and calcination, lithium cobaltate powder is obtained.

[0043] Specifically, the concentrations of lithium ions and cobalt ions in the aluminum-removed filtrate are measured, and the molar ratio of lithium ions to cobalt ions is adjusted by adding lithium salt. In some specific embodiments, the molar ratio can be (1.05-1.5):1, and the lithium salt used can be one or more of lithium acetate, lithium carbonate, lithium nitrate, lithium hydroxide, lithium oxalate, and lithium acetate.

[0044] At the same time, by adding a surfactant in the process of synthesizing lithium cobaltate material by sol-gel method, the size of lithium cobaltate particles can be controlled to improve the lithium ion diffusion rate, which is conducive to the improvement of electrochemical performance. In some specific embodiments, the surfactant can be one or more of ethylene glycol, dodecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, and polyethylene glycol. The addition ratio of the surfactant can be 1 g / L to 30 g / L. In addition, the pH value of the system is adjusted by adding a complexing agent. In some specific embodiments, ammonia water is selected as the complexing agent, and the pH value of the solution is adjusted to 4 to 7.

[0045] The sol is formed by water bath heating at 80℃ with magnetic stirring, and then evaporates moisture until a transparent colloid, i.e. a gel, is generated; further drying is performed until the transparent colloid is completely converted into a black solid; the dried solid product is calcined to obtain the regenerated lithium cobalt oxide powder.

[0046] The method provided by the embodiment is a lithium cobalt oxide battery cathode material recycling method based on supercritical hydrothermal oxidation. Oxidizing decomposition of the binder and the conductive additive on the lithium cobalt oxide battery cathode sheet is performed by supercritical water containing an oxidizing agent, so that the cathode material and the aluminum foil substrate are separated. Then, the filter residue is subjected to acid leaching by using an organic acid liquid containing a reducing agent, the cobalt element in the cathode material is leached out, and the aluminum-containing solid product is separated out by using an aluminum ion precipitating agent, so that the aluminum element is recycled. Finally, the leached cobalt element is synthesized into lithium cobalt oxide cathode material by using a sol-gel method, so that the lithium cobalt oxide is recycled and regenerated. The method uses supercritical hydrothermal oxidation to treat the binder and the conductive additive in the cathode sheet, does not need to use toxic and expensive organic solvents, can realize zero emission of toxic gas, can quickly and effectively remove the binder and the conductive additive, has high efficiency, and is environmentally friendly. In addition, in the subsequent ion recycling process, the sol-gel method is used to directly regenerate the lithium cobalt oxide material, so that the cobalt is recycled and the lithium cobalt oxide material is generated.

[0047] Further, on the basis of the above embodiment, the step S200 further includes:

[0048] The lithium ions are precipitated by adding a water-soluble carbonate into the hydrothermal filtrate, and lithium carbonate is obtained by filtration. Specifically, the water-soluble carbonate can be one or more of (NH4)2CO3, Na2CO3, K2CO3, Rb2CO3, and Cs2CO3. By recycling the lithium ions in the hydrothermal filtrate, the recovery rate of valuable metals in the waste lithium cobalt oxide battery is further improved.

[0049] Further, on the basis of the above embodiment, the acid leaching process in the step S200 can be performed in a heated environment, and a magnetic stirring device is used to stir the acid leaching solution. Specifically, the heating temperature can be 50℃-95℃, the stirring speed can be 100 r / min-500 r / min, and the time can be 30 min-300 min.

[0050] Further, on the basis of the above-mentioned embodiments, the positive electrode sheet of the lithium cobalt oxide battery to be recycled in step S100 is the positive electrode sheet obtained by disassembling and sorting the positive electrode sheet after the waste lithium cobalt oxide battery is fully discharged. Specifically, the waste lithium cobalt oxide battery can be discharged by using a physical discharge method and / or a chemical discharge method; after the electric quantity in the battery is completely released, the shell of the lithium battery is disassembled manually to obtain the inner core of the battery, and then the plastic film and the positive and negative electrodes of the lithium battery pack are sorted manually to obtain the positive electrode sheet of the lithium cobalt oxide battery to be recycled.

[0051] Further, on the basis of the above-mentioned embodiments, the positive electrode sheet of the lithium cobalt oxide battery to be recycled in step S100 is the positive electrode sheet obtained by disassembling and sorting the positive electrode sheet after the waste lithium cobalt oxide battery is fully discharged. Specifically, the waste lithium cobalt oxide battery can be discharged by using a physical discharge method and / or a chemical discharge method; after the electric quantity in the battery is completely released, the shell of the lithium battery is disassembled manually to obtain the inner core of the battery, and then the plastic film and the positive and negative electrodes of the lithium battery pack are sorted manually to obtain the positive electrode sheet of the lithium cobalt oxide battery to be recycled.

[0052] The mixed solution is evaporated to generate a wet gel, the wet gel is further dried to obtain a dry gel, and the dry gel is ground into a powder and then calcined in air. Specifically, the evaporation and drying process can be carried out in a forced air drying oven, the evaporation process is carried out at a temperature of 60-95°C, and the drying process is carried out at a temperature of 105-150°C. The calcination process in air can be carried out in a tube furnace or a muffle furnace, and can include two-stage calcination, wherein the first-stage calcination is carried out at a temperature of 300-500°C for 3-5h, and the second-stage calcination is carried out at a temperature of 600-900°C for 6-10h.

[0053] The specific process of the method will be described below in conjunction with a specific embodiment.

[0054] First, the 2032 button-type lithium cobalt oxide ion battery is fully discharged, and then the battery is manually disassembled to sort out the round sheet-shaped positive electrode sheet. A 36mL solution is obtained by mixing a 30% hydrogen peroxide solution and deionized water at a ratio of 5:4, and then 6g of the positive electrode sheet is mixed with the solution and placed in a 70mL hydrothermal reaction kettle. After the hydrothermal reaction kettle is sealed, it is placed in a pit furnace for heating and pressurization, so that the temperature inside the hydrothermal reaction kettle rises to 460°C and the pressure rises to 36MPa. The temperature inside the hydrothermal reaction kettle is controlled at 460°C and maintained for 60min. After the hydrothermal reaction kettle is cooled and depressurized, the product is taken out. Then the product is filtered and washed, and the hydrothermal filtrate and residue are collected. Sodium carbonate is added to the hydrothermal filtrate to recover lithium ions in the filtrate in the form of lithium carbonate precipitate.

[0055] The residue is subjected to acid leaching treatment, 1107mg of the residue is added to a mixed solution of citric acid and hydrogen peroxide, so that the solid-liquid ratio is 4:1g / L, the concentration of hydrogen peroxide in the acid leaching solution is 0.8mol / L, and the concentration of citric acid is 1.25mol / L. The mixture is heated to 90°C in a water bath for 30min, and is subjected to magnetic stirring at 200r / min.

[0056] The pH value of the acid leaching solution is adjusted by adding LiOH and ammonia solution, the acid leaching solution is filtered, and the aluminum element is recovered in the form of aluminum and aluminum hydroxide. The concentrations of lithium ions and cobalt ions in the aluminum-removed filtrate are measured, lithium acetate is added to adjust the concentration of lithium ions in the aluminum-removed filtrate, so that the molar ratio of lithium ions to cobalt ions is 1.05:1. At the same time, ammonia is added to adjust the pH value of the solution to 6, and 1 mL of ethylene glycol is added. The mixed solution is stirred uniformly and placed in a 90℃ air drying oven to evaporate water until a transparent colloid is formed; the transparent colloid is transferred to a 120℃ drying oven until the transparent colloid is completely converted into a black solid. The black solid is calcined in air at 450℃ for 5 hours, and then calcined at 850℃ for 8 hours to obtain a regenerated lithium cobalt oxide solid. Figure 2 The X-ray diffraction analysis image of the regenerated lithium cobalt oxide produced in this embodiment is shown, and it can be seen from the figure that a pure lithium cobalt oxide material is formed.

[0057] As can be seen from the above embodiments, the lithium cobalt oxide battery positive electrode material recovery method based on supercritical hydrothermal oxidation provided by the present application uses supercritical hydrothermal oxidation to treat the binder and conductive additive in the positive electrode sheet, without the need to use toxic and expensive organic solvents, while also achieving zero emission of toxic gases, and can quickly and effectively remove the binder and conductive additive, with high efficiency and environmental friendliness; in addition, in the subsequent ion recovery process, the sol-gel method is used to directly regenerate lithium cobalt oxide material, achieving the recovery of cobalt and the generation of lithium cobalt oxide material.

[0058] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for recovering lithium cobalt oxide battery cathode materials based on supercritical hydrothermal oxidation, characterized in that, include: The positive electrode of the lithium cobalt oxide battery to be recycled is mixed with an oxidant and deionized water, and a hydrothermal oxidation reaction is carried out under supercritical conditions. After the reaction is complete, solid-liquid separation is performed to obtain hydrothermal filtrate and filter residue. The temperature of the hydrothermal oxidation reaction is 380℃~600℃, the pressure is 24MPa~40MPa, and the time is 5min~200min, so that the internal oxidant aqueous solution system is in a high temperature and high pressure supercritical state above the critical point, thereby realizing the hydrothermal oxidation of binder and conductive additives. The filter residue is acid-leached with an organic acid solution containing a reducing agent. Cobalt and lithium are leached together into the aqueous solution by adding a reducing agent in an acidic system. An aluminum ion precipitant, namely lithium hydroxide and ammonia, is added to the acid leaching solution. After precipitation is complete, solid-liquid separation is performed to obtain an aluminum-containing solid product and an aluminum-removed filtrate. A lithium source, surfactant, and complexing agent are added to the aluminum removal filtrate to adjust the molar ratio of lithium ions and cobalt ions and the pH value of the solution. The mixed solution is then directly regenerated into lithium cobalt oxide powder by evaporation, drying, and calcination using the sol-gel method. The surfactant is one or more of ethylene glycol, dodecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, and polyethylene glycol.

2. The method for recovering lithium cobalt oxide battery cathode material based on supercritical hydrothermal oxidation according to claim 1, characterized in that, Also includes: Water-soluble carbonates are added to the hydrothermal filtrate to precipitate lithium ions, and lithium carbonate is obtained by filtration.

3. The method for recovering lithium cobalt oxide battery cathode material based on supercritical hydrothermal oxidation according to claim 1, characterized in that, The positive electrode of the lithium cobalt oxide battery to be recycled is the positive electrode obtained by disassembling and sorting the waste lithium cobalt oxide battery after it has been fully discharged.

4. The method for recovering lithium cobalt oxide battery cathode material based on supercritical hydrothermal oxidation according to claim 1, characterized in that, The amount of oxidant added is 1 mol / L to 12 mol / L.

5. The method for recovering lithium cobalt oxide battery cathode material based on supercritical hydrothermal oxidation according to claim 1, characterized in that, The acid leaching process is carried out under heating conditions, and the acid leaching solution is stirred using a magnetic stirring device; the amount of reducing agent added is 0.1 mol / L to 4 mol / L; the concentration of the organic acid solution is 0.1 mol / L to 5 mol / L.

6. The method for recovering lithium cobalt oxide battery cathode material based on supercritical hydrothermal oxidation according to claim 1, characterized in that, An aluminum ion precipitant is added to the acid leaching solution to adjust the pH value to 3-6.

7. The method for recovering lithium cobalt oxide battery cathode material based on supercritical hydrothermal oxidation according to claim 1, characterized in that, Lithium salt is added to the aluminum-removing filtrate to adjust the molar ratio of lithium ions to cobalt ions in the solution to (1.05~1.5):1; A complexing agent is added to the aluminum removal filtrate to adjust the pH of the solution to 4-7; at the same time, the surfactant is added at a ratio of 1g / L to 30g / L.

8. The method for recovering lithium cobalt oxide battery cathode material based on supercritical hydrothermal oxidation according to claim 1, characterized in that, The process of evaporating, drying, and calcining the mixed solution further includes: The mixed solution is evaporated until a gel is formed. The gel is then further dried, and the dried solid product is ground into powder and calcined in air.

9. The method for recovering lithium cobalt oxide battery cathode material based on supercritical hydrothermal oxidation according to claim 8, characterized in that, The evaporation of moisture is carried out at a temperature of 60℃~95℃; the drying process is carried out at a temperature of 105℃~150℃; the calcination process in air includes two stages of calcination, wherein the first stage of calcination is carried out at a temperature of 300℃~500℃ for 3h~5h, and the second stage of calcination is carried out at a temperature of 600℃~900℃ for 6h~10h.

10. The method for recovering lithium cobalt oxide battery cathode material based on supercritical hydrothermal oxidation according to any one of claims 1 to 9, characterized in that, The oxidant is one or more of hydrogen peroxide, oxygen, potassium permanganate, ammonium persulfate, sodium percarbonate, sodium peroxide, potassium peroxide, calcium peroxide, and lithium peroxide. The reducing agent is one or more of hydrogen peroxide, ascorbic acid, formaldehyde, glucose, carbon monoxide, and hydrogen. The organic acid solution is one or more of citric acid, ascorbic acid, oxalic acid, formic acid, acetic acid, succinic acid, and tartaric acid; The lithium source is one or more of lithium acetate, lithium carbonate, lithium nitrate, lithium hydroxide, lithium oxalate, and lithium acetate. The complexing agent is ammonia.

Images