Method for high-value utilization of positive electrode material of waste lithium cobalt oxide battery

Abstract

The invention provides a method for high-valued utilization of a positive electrode material of a waste lithium cobalt oxide battery, and belongs to the technical field of cyclic utilization of positive electrode materials of waste batteries. The lithium cobalt oxide powder in the positive electrode material of the waste lithium cobalt oxide battery is subjected to acid leaching to obtain the cobalt-containing leaching solution, then the cobalt-containing leaching solution is directly subjected to hydrothermal reaction with urea and ammonium fluoride to obtain the intermediate, the intermediate reacts with the oxidizing agent to obtain the hydroxyl cobalt oxide, metal separation steps such as extraction and reverse extraction are not needed, the method is simpler, and the cost is lower. And the prepared hydroxyl cobalt oxide has excellent catalytic performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of recycling of waste positive electrode materials, and particularly relates to a method for high-value utilization of waste lithium cobalt oxide battery positive electrode materials. BACKGROUND

[0002] With the rapid development of electric vehicles and renewable energy storage industries, the demand for batteries continues to rise. However, if batteries are not properly disposed of at the end of their service life, they will cause serious solid waste pollution problems and result in a huge waste of valuable metal resources such as cobalt, nickel and lithium. Efficient recovery of these metals not only helps to alleviate the supply pressure of primary resources and reduce environmental risks, but also realizes the dual benefits of economy and environmental protection. Therefore, the recycling and utilization of valuable metals in power batteries has important resource and environmental protection significance.

[0003] Lithium cobalt oxide batteries, as a kind of lithium ion battery widely used in mobile electronic devices, electric vehicles and energy storage systems, have significant recycling potential due to the presence of high-value cobalt elements. Using recycled cobalt to develop functional materials with low cost, high activity and high stability is a forward-looking resource utilization path. In the prior art, cobalt and lithium metal in waste lithium cobalt oxide battery positive electrode materials are dissolved by citric acid and hydrogen peroxide, and then extracted and separated to obtain cobalt sulfate, which is then used to synthesize cobalt hydroxide. However, this method requires extraction, stripping and other processes, and the process is relatively complex. SUMMARY

[0004] The purpose of the present application is to provide a method for high-value utilization of waste lithium cobalt oxide battery positive electrode materials. The method provided by the present application is simple, and the hydroxyl cobalt prepared thereby has excellent catalytic performance.

[0005] In order to achieve the above-mentioned purpose of the application, the present application provides the following technical solutions: The present application provides a method for high-value utilization of waste lithium cobalt oxide battery positive electrode materials, comprising the following steps: (1) mixing lithium cobalt oxide powder in waste lithium cobalt oxide battery positive electrode materials with inorganic acid solution and hydrogen peroxide, and performing acid leaching to obtain a leaching solution; (2) mixing the leaching solution obtained in step (1) with a first alkali solution, urea and ammonium fluoride, and performing hydrothermal reaction to obtain an intermediate; (3) mixing the intermediate obtained in step (2) with water, a second alkali solution and an oxidizing agent, and performing oxidation reaction to obtain hydroxyl cobalt.

[0006] Preferably, the inorganic acid solution in step (1) comprises one or more of hydrochloric acid, sulfuric acid and nitric acid.

[0007] Preferably, the mass of the lithium cobalt oxide powder in step (1) to the total volume of the inorganic acid solution and hydrogen peroxide is (20-50) g: 1 L.

[0008] Preferably, the temperature of the acid leaching in step (1) is 30-80℃, and the acid leaching time is 0.5-2 h.

[0009] Preferably, the pH value of the leaching solution mixed with the first alkali solution in step (2) is 2.5-3.5.

[0010] Preferably, the molar ratio of cobalt ions to ammonium fluoride in the leaching solution in step (2) is 1:(1-5), and the molar ratio of cobalt ions to urea in the leaching solution is 1:(1-5).

[0011] Preferably, the temperature of the hydrothermal reaction in step (2) is 100-150℃, and the hydrothermal reaction time is 4-10 h.

[0012] Preferably, the pH value of the intermediate mixed with water and the second alkali solution in step (3) is 11.5-12.5.

[0013] Preferably, the oxidizing agent in step (3) includes one or more of hydrogen peroxide, sodium hypochlorite solution, and sodium persulfate solution.

[0014] Preferably, the temperature of the oxidation reaction in step (3) is 40-100℃, and the oxidation reaction time is 1-5 h.

[0015] The present application provides a method for high-value utilization of waste lithium cobalt oxide battery positive electrode material, comprising the following steps: (1) mixing lithium cobalt oxide powder in waste lithium cobalt oxide battery positive electrode material with inorganic acid solution and hydrogen peroxide, and performing acid leaching to obtain a leaching solution; (2) mixing the leaching solution obtained in step (1) with a first alkali solution, urea and ammonium fluoride, and performing a hydrothermal reaction to obtain an intermediate; (3) mixing the intermediate obtained in step (2) with water, a second alkali solution and an oxidizing agent, and performing an oxidation reaction to obtain cobalt hydroxyl oxide. The present application first performs acid leaching on lithium cobalt oxide powder in waste lithium cobalt oxide battery positive electrode material to obtain a cobalt-containing leaching solution, then directly performs a hydrothermal reaction with urea and ammonium fluoride to obtain an intermediate, and then reacts with an oxidizing agent to obtain cobalt hydroxyl oxide, without the need for metal separation steps such as extraction and back extraction, the method is simpler, and the prepared cobalt hydroxyl oxide has excellent catalytic performance. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The flowchart of the method for high-value utilization of a waste lithium cobalt oxide battery positive electrode material in Example 1; Figure 2 The XRD pattern of the cobalt hydroxyl oxide prepared in Example 1; Figure 3 XPS chart of cobalt oxyhydroxide prepared for Example 1; Figure 4 SEM chart of cobalt oxyhydroxide prepared for Example 1. DETAILED DESCRIPTION

[0017] The application provides a method for high-value utilization of waste lithium cobalt oxide battery positive electrode material, comprising the following steps: (1) mixing lithium cobalt oxide powder in waste lithium cobalt oxide battery positive electrode material with inorganic acid liquid and hydrogen peroxide, performing acid immersion to obtain leaching liquor; (2) mixing the leaching liquor obtained in the step (1) with first alkali liquid, urea and ammonium fluoride, performing hydrothermal reaction to obtain intermediate; (3) mixing the intermediate obtained in the step (2) with water, second alkali liquid and oxidizing agent, performing oxidation reaction to obtain cobalt oxyhydroxide.

[0018] Unless otherwise specified, the source of each raw material is not particularly limited in the application, and commercially available products known to those skilled in the art can be used.

[0019] In the application, lithium cobalt oxide powder in waste lithium cobalt oxide battery positive electrode material is mixed with inorganic acid liquid and hydrogen peroxide, and acid immersion is performed to obtain leaching liquor.

[0020] As an embodiment, lithium cobalt oxide powder in waste lithium cobalt oxide battery positive electrode material is obtained by sequentially discharging and disassembling waste lithium cobalt oxide battery.

[0021] The application does not have a special limitation on the operation of discharging and disassembling, and lithium cobalt oxide powder in the positive electrode material can be obtained by using a technical solution known to those skilled in the art.

[0022] In the application, the mixing of lithium cobalt oxide powder in waste lithium cobalt oxide battery positive electrode material with inorganic acid liquid and hydrogen peroxide is preferably as follows: mixing inorganic acid liquid and hydrogen peroxide to obtain leaching agent, and mixing lithium cobalt oxide powder with the leaching agent.

[0023] In the application, water is preferably added when the inorganic acid liquid and hydrogen peroxide are mixed. The application does not have a special limitation on the amount of water, and the concentration of inorganic acid and hydrogen peroxide in the leaching agent can be ensured to be within the required range.

[0024] In the application, the inorganic acid liquid preferably comprises one or more of hydrochloric acid, sulfuric acid and nitric acid.

[0025] In the present application, the concentration of the inorganic acid in the leaching agent is preferably 0.5-4 mol / L; the mass concentration of hydrogen peroxide in the leaching agent is preferably 5-20%. As an embodiment, the concentration of the inorganic acid in the leaching agent can be specifically 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L or 4 mol / L; the mass concentration of hydrogen peroxide in the leaching agent can be specifically 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%. The present application does not have special limitations on the concentration and amount of the inorganic acid solution and hydrogen peroxide, as long as the concentration of the inorganic acid and hydrogen peroxide in the leaching agent is within the required range.

[0026] In the present application, the mass of the lithium cobalt oxide powder to the volume of the leaching agent is preferably (20-50) g: 1 L, that is, the mass of the lithium cobalt oxide powder to the total volume of the inorganic acid solution and hydrogen peroxide or the mass of the lithium cobalt oxide powder to the total volume of the inorganic acid solution, hydrogen peroxide and water is preferably (20-50) g: 1 L. As an embodiment, the mass of the lithium cobalt oxide powder to the volume of the leaching agent can be specifically 20 g: 1 L, 25 g: 1 L, 30 g: 1 L, 35 g: 1 L, 40 g: 1 L, 45 g: 1 L or 50 g: 1 L.

[0027] In the present application, the temperature of the acid leaching is preferably 30-80℃; the time of the acid leaching is preferably 0.5-2 h; the acid leaching is preferably carried out under stirring. The present application does not have special limitations on the mode and rate of stirring, and the technical solutions well known to those skilled in the art can be used. As an embodiment, the temperature of the acid leaching can be specifically 30℃, 40℃, 50℃, 60℃, 70℃ or 80℃; the time of the acid leaching can be specifically 0.5 h, 1 h, 1.5 h or 2 h.

[0028] By controlling the composition, amount of the leaching agent, temperature and time of the acid leaching within the above ranges, the present application can make the metals in the lithium cobalt oxide powder be fully leached out.

[0029] After the acid leaching is completed, the present application preferably filters the product after the acid leaching to obtain a leaching solution.

[0030] The present application does not have special limitations on the operation of filtering, and the technical solutions well known to those skilled in the art can be used to remove the solid.

[0031] After the leaching solution is obtained, the present application mixes the leaching solution with a first alkali solution, urea and ammonium fluoride to carry out a hydrothermal reaction to obtain an intermediate.

[0032] In the present application, the first alkali solution preferably comprises one or more of sodium hydroxide solution, potassium hydroxide solution and ammonia water. The present application does not have special limitations on the concentration and amount of the first alkali solution, as long as the pH value of the leaching solution after mixing with the first alkali solution is within the required range.

[0033] In the present application, the pH value of the leaching solution after mixing with the first alkali solution is preferably 2.5-3.5. As an embodiment, the pH value of the leaching solution after mixing with the first alkali solution can be specifically 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4 or 3.5. The present application controls the pH value of the leaching solution after mixing with the first alkali solution within the above range, which is more conducive to the subsequent hydrothermal reaction.

[0034] In the present application, the molar ratio of cobalt ions to ammonium fluoride in the leaching solution is preferably 1:(1-5); the molar ratio of cobalt ions to urea in the leaching solution is preferably 1:(1-5). As an embodiment, the molar ratio of cobalt ions to ammonium fluoride in the leaching solution can be specifically 1:1, 1:2, 1:3, 1:4 or 1:5; the molar ratio of cobalt ions to urea in the leaching solution can be specifically 1:1, 1:2, 1:3, 1:4 or 1:5.

[0035] In the present application, the mixing of the leaching solution with the first alkali solution, urea and ammonium fluoride is preferably: mixing the leaching solution with the first alkali solution, and then adding urea and ammonium fluoride.

[0036] In the present application, when mixing the leaching solution with the first alkali solution, urea and ammonium fluoride, water is also preferably added. The present application adds water to avoid too low content of the leaching solution, which is not conducive to the subsequent hydrothermal reaction.

[0037] In the present application, when water is added, the pH value of the leaching solution after mixing with water and the first alkali solution is preferably 2.5-3.5.

[0038] In the present application, when water is added, the mixing of the leaching solution, water, the first alkali solution, urea and ammonium fluoride is preferably: mixing the leaching solution with water, adding the first alkali solution, and then adding urea and ammonium fluoride.

[0039] The present application does not have special limitations on the amount of water, as long as the hydrothermal reaction can proceed smoothly according to actual needs.

[0040] As an embodiment, when the content of cobalt ions in the leaching solution is 1-4 mmol, the leaching solution is mixed with water to a volume of 30 mL.

[0041] In the present application, the temperature of the hydrothermal reaction is preferably 100-150℃; the time of the hydrothermal reaction is preferably 4-10h. As an implementation form, the temperature of the hydrothermal reaction can be specifically 100℃, 110℃, 120℃, 130℃, 140℃ or 150℃; the time of the hydrothermal reaction can be specifically 4h, 5h, 6h, 7h, 8h, 9h or 10h.

[0042] In the present application, the types, amounts, reaction temperature and time of the raw materials in the hydrothermal reaction are controlled within the above ranges, so that the cobalt in the leaching solution can be reacted to obtain a relatively pure cobalt-containing intermediate, and the pure cobalt hydroxide can be obtained through subsequent reactions, thereby ensuring that the obtained cobalt hydroxide has excellent catalytic performance.

[0043] After the hydrothermal reaction is completed, the product of the hydrothermal reaction is preferably sequentially cooled, centrifuged, washed and dried to obtain the intermediate.

[0044] The operation of cooling, centrifuging, washing and drying in the present application is not specially limited, and a technical solution well known to those skilled in the art can be adopted.

[0045] In the present application, the intermediate is Co(OH)F.

[0046] After the intermediate is obtained, the intermediate is mixed with water, a second lye and an oxidizing agent to perform an oxidation reaction, thereby obtaining cobalt hydroxide.

[0047] In the present application, the mass-to-volume ratio of the intermediate to water is preferably 50mg:(30-50)mL. As an implementation form, the mass-to-volume ratio of the intermediate to water can be specifically 50mg:30mL, 50mg:35mL, 50mg:40mL, 50mg:45mL or 50mg:50mL.

[0048] In the present application, the second lye preferably includes one or more of a sodium hydroxide solution, a potassium hydroxide solution and ammonia water.

[0049] The concentration and amount of the second lye in the present application are not specially limited, and the pH value of the mixture of the intermediate, water and the second lye after mixing is only required to be within a required range.

[0050] In the present application, the pH value of the mixture of the intermediate, water and the second lye after mixing is preferably 11.5-12.5. As an implementation form, the pH value of the mixture of the intermediate, water and the second lye after mixing can be specifically 11.5, 11.6, 11.7, 11.8, 11.9, 12, 12.1, 12.2, 12.3, 12.4 or 12.5.

[0051] In the present application, the oxidizing agent preferably comprises one or more of hydrogen peroxide, sodium hypochlorite solution and sodium persulfate solution.

[0052] In the present application, the mass concentration of the hydrogen peroxide is preferably 25-35%. As an embodiment, the mass concentration of the hydrogen peroxide can be specifically 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34% or 35%.

[0053] In the present application, the mass concentration of the sodium hypochlorite solution is preferably 4-6%. As an embodiment, the mass concentration of the sodium hypochlorite solution can be specifically 4%, 5% or 6%.

[0054] In the present application, the concentration of the sodium persulfate solution is preferably 0.05-0.5 mol / L.

[0055] In the present application, the mass of the intermediate and the volume of the oxidizing agent are preferably 50 mg: (1-5) mL.

[0056] In the present application, the mixing of the intermediate, water, the second alkali solution and the oxidizing agent is preferably: mixing the intermediate with water, then adding the second alkali solution, and then adding the oxidizing agent.

[0057] In the present application, the temperature of the oxidation reaction is preferably 40-100℃; the time of the oxidation reaction is preferably 1-5 h. As an embodiment, the temperature of the oxidation reaction can be specifically 40℃, 50℃, 60℃, 70℃, 80℃, 90℃ or 100℃; the time of the oxidation reaction can be specifically 1 h, 2 h, 3 h, 4 h or 5 h.

[0058] By controlling the amount of each raw material, the reaction temperature and time and other parameters within the above ranges, the present application can make the intermediate fully react to form cobalt hydroxyl oxide, and the prepared cobalt hydroxyl oxide has excellent catalytic performance.

[0059] After the oxidation reaction is completed, the present application preferably sequentially cools, centrifugates, washes and dries the product of the oxidation reaction to obtain cobalt hydroxyl oxide.

[0060] The present application does not have special limitations on the cooling, centrifugation, washing and drying operations, and any technical solution known to those skilled in the art can be used.

[0061] The application uses lithium cobalt oxide powder in waste lithium cobalt oxide battery positive electrode material as a cobalt source, directly uses a metal leaching solution to hydrothermally react with urea and ammonium fluoride to synthesize an intermediate, and then reacts with an oxidizing agent to obtain flaky cobalt hydroxyl oxide, without a metal separation step such as extraction, the method is simple, the preparation method used is a conventional hydrothermal reaction, the equipment is simple, easy to scale up, suitable for large-scale production, high-value cobalt hydroxyl oxide is prepared from waste lithium cobalt oxide battery material, waste reuse and environmental protection are realized, and the application has important economic and social benefits, and provides more ideas for improving the added value of waste batteries, and the prepared cobalt hydroxyl oxide has excellent electrocatalytic oxygen evolution reaction performance.

[0062] The technical solutions in the application will be clearly and completely described below in combination with the embodiments in the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the application.

[0063] Embodiment 1 A method for high-value utilization of waste lithium cobalt oxide battery positive electrode material is as follows: (1) after the waste lithium cobalt oxide battery is soaked in a 10% sodium chloride solution for 24 h and fully discharged, the battery is disassembled to obtain positive electrode sheets and negative electrode sheets, and then positive electrode powder is separated from the positive electrode sheets to obtain lithium cobalt oxide powder; (2) sulfuric acid, hydrogen peroxide and deionized water are mixed to obtain a leaching agent of 1 mol / L H2SO4+5% H2O2 by mass concentration; (3) 3 g of lithium cobalt oxide powder is mixed with the leaching agent at a ratio of 40 g:1 L, and stirred at 60℃ for 2 h of acid leaching, and then filtered to obtain a leaching solution; (4) the leaching solution (the content of cobalt ions in the leaching solution is 4 mmol) is added with water to 30 mL, a sodium hydroxide solution is added to adjust the pH value to 3, then 4 mmol of ammonium fluoride and 8 mmol of urea are added, and stirred for 20 min, and then transferred to a high-pressure reaction kettle for hydrothermal reaction at 120℃ for 6 h, after the reaction is completed, sequentially cooled, centrifuged, washed and dried to obtain an intermediate Co(OH)F, and the recovery rate of Co is 99.7%; (5) 50 mg of the intermediate is added to 40 mL of water, a 1 mol / L sodium hydroxide solution is used to adjust the pH value to 12, then 4 mL of 30% hydrogen peroxide by mass concentration is added, and oxidation reaction is carried out at 50℃ for 3 h, after the reaction is completed, sequentially cooled, centrifuged, washed and dried to obtain brown-black powder cobalt hydroxyl oxide.

[0064] A flow chart of the method for high-value utilization of waste lithium cobalt oxide battery positive electrode material in embodiment 1 is as shown in Figure 1 .

[0065] The XRD pattern of the cobalt oxyhydroxide prepared in Example 1 is shown in FIG. 1. Figure 2 From the XRD data, it can be seen that the product prepared in Example 1 is consistent with cobalt oxyhydroxide (PDF 07-0169). Figure 2

[0066] The XPS pattern of the cobalt oxyhydroxide prepared in Example 1 is shown in FIG. 2. Figure 3 From the XPS data, it can be seen that there is no other impurity in the product prepared. Figure 3

[0067] The SEM pattern of the cobalt oxyhydroxide prepared in Example 1 is shown in FIG. 3. Figure 4 From the SEM data, it can be seen that the product prepared is flaky cobalt oxyhydroxide. Figure 4

[0068] The cobalt oxyhydroxide prepared in Example 1 was prepared into an electrocatalytic electrode to evaluate the electrocatalytic oxygen evolution reaction (OER) performance of the sample on an electrochemical workstation. Specifically, first, 10 mg of the prepared cobalt oxyhydroxide powder and 200 μL of a Nafion solution as an adhesive were added to 0.8 mL of a mixed solution of ethanol-water (volume ratio 1:1), and ultrasonic dispersion was performed to form a viscous suspension. A 0.25 cm carbon paper was cut and fixed with a platinum sheet electrode clamp, 25 μL of the suspension was evenly coated on the carbon paper, and it was naturally air-dried as a working electrode. Second, a platinum sheet and a mercury oxide electrode were used as a counter electrode and a reference electrode, respectively, 1.0 mol / L KOH solution was used as an electrolyte, linear voltammetry scanning was performed, the voltage range was -0.2~0.8 V (vs. Hg / HgO), and the scanning speed was 2 mV s -1 -1. The electrocatalytic oxygen evolution reaction (OER) performance was evaluated. The results showed that the overpotential was 312 mV at a current of 10 mA / cm 2 -2.

[0069] Example 2 A method for high-value utilization of a positive electrode material of a waste lithium cobalt oxide battery is as follows: (1) the waste lithium cobalt oxide battery is soaked in a 10% sodium chloride solution for 24 h to fully discharge, then it is disassembled to obtain a positive electrode sheet and a negative electrode sheet, and then the positive electrode powder is separated from the positive electrode sheet to obtain lithium cobalt oxide powder; (2) nitric acid, hydrogen peroxide and deionized water are mixed to obtain a leaching agent of 3 mol / L HNO3+10% H2O2 by mass concentration; (3) 3 g of lithium cobalt oxide powder is mixed with the leaching agent at a ratio of 50 g:1 L, stirred at 60°C for 1 h, filtered, and a leaching solution is obtained; ​​​​(4) Take the leaching solution (the cobalt ion content in the leaching solution is 2 mmol) and add water to 30 mL, add sodium hydroxide solution to adjust the pH value to 3, then add 4 mmol of ammonium fluoride and 4 mmol of urea, stir for 20 min, and transfer to a high-pressure reaction kettle for hydrothermal reaction at 120°C for 4 h. After the reaction is completed, it is cooled, centrifuged, washed and dried in sequence to obtain an intermediate Co(OH)F, and the cobalt recovery rate is 98.6%; (5) Take 50 mg of the intermediate and add 40 mL of water, adjust the pH value to 12 with 1 mol / L sodium hydroxide solution, then add 5 mL of 5% mass concentration sodium hypochlorite solution, and perform oxidation reaction at 60°C for 5 h. After the reaction is completed, it is cooled, centrifuged, washed and dried in sequence to obtain brown-black powder cobalt hydroxyl oxide.

[0070] The cobalt hydroxyl oxide prepared in Example 2 is prepared into an electrocatalytic electrode to evaluate the electrocatalytic oxygen evolution reaction (OER) performance of the sample on an electrochemical workstation. Specifically, first, 10 mg of the prepared cobalt hydroxyl oxide powder and 200 μL of Nafion solution as an adhesive are added to 0.8 mL of a mixed solution of ethanol-water (volume ratio 1:1), and ultrasonic dispersion is performed to form a viscous suspension. A 0.25 cm carbon paper is cut and fixed with a platinum sheet electrode clamp, 25 μL of the suspension is uniformly coated on the carbon paper, and it is naturally air-dried as a working electrode. Second, a platinum sheet and a mercury oxide electrode are used as a counter electrode and a reference electrode respectively, and 1.0 mol / L KOH solution is used as an electrolyte. Linear voltammetry scanning is performed with a voltage range of -0.2~0.8 V (vs. Hg / HgO) and a scanning speed of 2 mV s -1 . The electrocatalytic oxygen evolution reaction (OER) performance is evaluated. The results show that the overpotential is 321 mV at a current of 10 mA / cm 2 .

[0071] Example 3 A method for high-value utilization of a positive electrode material of a waste lithium cobalt oxide battery is as follows: (1) The waste lithium cobalt oxide battery is soaked in a 10% mass concentration sodium chloride solution for 24 h to fully discharge, then it is disassembled to obtain a positive electrode sheet and a negative electrode sheet, and then the positive electrode powder is separated from the positive electrode sheet to obtain lithium cobalt oxide powder; (2) Sulfuric acid, hydrogen peroxide and deionized water are mixed to obtain a leaching agent of 4 mol / L H2SO4+10% mass concentration H2O2; (3) 3 g of lithium cobalt oxide powder is mixed with the leaching agent at a ratio of 20 g:1 L, stirred at 60°C for 1 h, and filtered to obtain a leaching solution; (4) Take the leaching solution (cobalt ion content in the leaching solution is 3mmol) and add water to 30mL, add sodium hydroxide solution to adjust the pH value to 3, then add 6mmol of ammonium fluoride and 6mmol of urea, stir for 20min, and transfer to a high-pressure reaction kettle, and hydrothermal reaction is carried out at 120℃ for 6h, after the reaction is completed, cooling, centrifugation, washing and drying are carried out in sequence, and the intermediate Co(OH)F is obtained, and the cobalt recovery rate is 98.8%; (5) Take 50mg of the intermediate and add 40mL of water, adjust the pH value to 12 with 1mol / L sodium hydroxide solution, then add 4mL of 30% hydrogen peroxide, and oxidation reaction is carried out at 40℃ for 3h, after the reaction is completed, cooling, centrifugation, washing and drying are carried out in sequence, and the brown-black powder cobalt hydroxyl oxide is obtained.

[0072] The cobalt hydroxyl oxide prepared in Example 3 is prepared into an electrocatalytic electrode, and the electrocatalytic oxygen evolution reaction (OER) performance of the sample is evaluated on an electrochemical workstation. Specifically, first, 10mg of the prepared cobalt hydroxyl oxide powder and 200ul of a Nafion solution as an adhesive are added to 0.8ml of a mixed solution of ethanol-water (volume ratio 1:1), and ultrasonic dispersion is carried out to form a viscous suspension. A 0.25 cm carbon paper is cut and fixed with a platinum sheet electrode clamp, 50ul of the suspension is evenly coated on the carbon paper, and natural air drying is carried out, serving as a working electrode. Secondly, a platinum sheet and a mercury oxide electrode are used as a counter electrode and a reference electrode respectively, 1.0mol / L KOH solution is used as an electrolyte, linear voltammetry scanning is carried out, the voltage range is-0.2~0.8V (vs. Hg / HgO), and the scanning speed is 2mV s -1 . The electrocatalytic oxygen evolution reaction (OER) performance is evaluated. The results show that the overpotential is 305mV at a current of 10mA / cm 2 .

[0073] In summary, the cobalt hydroxyl oxide with high added value is prepared by taking the lithium cobalt oxide powder in the positive electrode material of the waste lithium cobalt oxide battery as a cobalt source, and the prepared cobalt hydroxyl oxide has excellent electrocatalytic performance.

[0074] The above only describes the preferred embodiments of the present application, and it should be pointed out that for ordinary skilled persons in the art, some improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be regarded as the protection scope of the present application.

Claims

1. A method for high-value utilization of a positive electrode material of a waste lithium cobalt oxide battery, comprising the following steps: (1) mixing lithium cobalt oxide powder in the positive electrode material of the waste lithium cobalt oxide battery with inorganic acid liquid and hydrogen peroxide, and performing acid leaching to obtain a leaching solution; (2) mixing the leaching solution obtained in the step (1) with first alkali liquid, urea and ammonium fluoride, and performing hydrothermal reaction to obtain an intermediate; (3) mixing the intermediate obtained in the step (2) with water, second alkali liquid and oxidizing agent, and performing oxidation reaction to obtain cobalt hydroxide oxide.

2. The method of claim 1, wherein, The inorganic acid liquid in the step (1) comprises one or more of hydrochloric acid, sulfuric acid and nitric acid.

3. The method of claim 1, wherein, The mass of the lithium cobalt oxide powder in the step (1) to the total volume of the inorganic acid liquid and hydrogen peroxide is (20-50) g: 1 L.

4. The method of claim 1, wherein, The temperature of the acid leaching in the step (1) is 30-80 ℃, and the acid leaching time is 0.5-2 h.

5. The method of claim 1, wherein, The pH value after mixing the leaching solution and the first alkali liquid in the step (2) is 2.5-3.

5.

6. The method of claim 1, wherein, The molar ratio of cobalt ions in the leaching solution to ammonium fluoride in the step (2) is 1: (1-5), and the molar ratio of cobalt ions in the leaching solution to urea is 1: (1-5).

7. The method of claim 1, wherein, The temperature of the hydrothermal reaction in the step (2) is 100-150 ℃, and the hydrothermal reaction time is 4-10 h.

8. The method of claim 1, wherein, The pH value after mixing the intermediate and water and the second alkali liquid in the step (3) is 11.5-12.

5.

9. The method of claim 1, wherein, The oxidizing agent in the step (3) comprises one or more of hydrogen peroxide, sodium hypochlorite solution and sodium persulfate solution.

10. The method of claim 1, wherein, The temperature of the oxidation reaction in the step (3) is 40-100 ℃, and the oxidation reaction time is 1-5 h.

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