A resource recycling method based on metal extraction from waste lithium ion batteries

Abstract

This invention discloses a method for resource recycling based on metal extraction from spent lithium-ion batteries, belonging to the field of electrocatalysis technology. The method includes the following steps: disassembling spent lithium-ion batteries and collecting cathode powder; mixing the cathode powder, distilled water, and a weak acid evenly; subjecting the resulting mixture to water bath heating and ultrasonic treatment to obtain a metal ion leaching solution; mixing the metal ion leaching solution with urea and ammonium persulfate, and transferring it to a reaction vessel containing a current collector for hydrothermal reaction, thereby growing an electrocatalytic electrode in situ on the surface of the current collector; wherein the current collector is a copper oxide nanowire loaded on a copper foam substrate. This approach eliminates the long process and high pollution steps of traditional metallurgy, upgrading low-value solid waste into high-value-added electrocatalytic materials, providing a new approach for the green closed-loop recycling of lithium-ion batteries and the low-cost manufacturing of electrocatalytic electrodes.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalysis technology, and in particular relates to a method for resource recycling based on extracting metals from waste lithium-ion batteries. Background Technology

[0002] Lithium-ion batteries, as core energy storage components in new energy vehicles, energy storage systems, and consumer electronics, have entered a phase of large-scale retirement due to the rapid development of related industries and the advancement of their life cycle. The cathode materials of spent lithium-ion batteries are rich in strategic metals such as lithium, iron, cobalt, nickel, and manganese, making them solid waste resources with significant recycling value. Their efficient recycling and utilization are of great importance to resource recycling and environmental protection.

[0003] Currently, the mainstream resource recovery technologies for spent lithium-ion batteries mainly include hydrometallurgy and pyrometallurgy. However, these technologies generally suffer from inherent bottlenecks such as high consumption of strong acids / alkalis, high energy consumption, lengthy process flows, reduced grade of recycled materials, and severe secondary pollution, making it difficult to simultaneously achieve the dual goals of efficient resource recovery and environmentally friendly development. Therefore, there is an urgent need to develop a new green resource recovery process that is short-process, low-pollution, high-recovery-rate, and capable of directly regenerating high-value-added materials.

[0004] To overcome the shortcomings of the aforementioned metallurgical routes, current research proposes directly converting the mixed transition metal components in spent batteries into high-value-added functional materials. Among these, using spent lithium-ion battery cathode materials (rich in Fe, Co, Ni, and Mn) as the transition metal source and growing electrocatalytic electrodes in situ on conductive current collectors is a highly promising technological approach. This strategy bypasses the complex metal separation-purification-resynthesis process, significantly reducing acid / alkali consumption and secondary pollution. Simultaneously, leveraging the structural advantages of the current collector, high catalyst loading, uniform distribution, and robust anchoring can be achieved. The prepared electrodes can be applied in energy and environmental catalysis fields such as water electrolysis for oxygen and hydrogen evolution, electrocatalytic reduction of nitrate to ammonia, and electrocatalytic reduction of carbon dioxide.

[0005] Nevertheless, research on the direct synthesis of electrocatalytic materials from recycled lithium-ion battery solutions is still in its early stages and faces two major challenges: First, existing methods mostly rely on strong acid leaching and metal purification steps, and the leaching residue is prone to causing secondary pollution, failing to truly achieve the goal of "green and short process"; Second, the proportion of transition metal ions in the cathode material of waste batteries is uncontrollable, making it difficult to match the design requirements in the preparation process of catalytic electrodes, resulting in the activity and stability of the prepared electrodes being far lower than those of materials obtained using pure chemicals as precursors.

[0006] In summary, existing technologies for the resource recovery of spent lithium-ion batteries and methods for preparing electrocatalytic electrodes still have many shortcomings, and there is an urgent need to develop a new method. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention proposes a method for resource recycling based on extracting metals from spent lithium-ion batteries.

[0008] To achieve the above objectives, the present invention provides the following technical solution: A method for resource recycling based on extracting metals from spent lithium-ion batteries includes the following steps: Disassemble used lithium-ion batteries and collect the positive electrode powder; The positive electrode powder, distilled water and weak acid are mixed evenly, and the resulting mixture is subjected to water bath heating and ultrasonic treatment to obtain a metal ion leaching solution. The metal ion leachate is mixed with urea and ammonium persulfate and transferred to a reactor containing a current collector for hydrothermal reaction, thereby growing an electrocatalytic electrode in situ on the surface of the current collector. The current collector is a current collector on a copper foam substrate loaded with copper oxide nanowires.

[0009] This invention utilizes a weak acid to leach mixed transition metal ions from the cathode of spent lithium-ion batteries as a metal source, directly constructing an electrocatalytic electrode on the current collector surface. This achieves a highly efficient resource recovery path from "retired battery → mixed metal solution → functional catalytic electrode." This route eliminates the long process and highly polluting steps of traditional metallurgy, upgrading low-value solid waste into high-value-added electrocatalytic materials. It provides a novel approach for the green closed-loop recycling of lithium-ion batteries and the low-cost manufacturing of electrocatalytic electrodes.

[0010] Furthermore, the waste lithium-ion batteries are selected from one or more of the following: waste high-nickel ternary lithium batteries, lithium iron phosphate batteries, lithium cobalt oxide batteries, and lithium manganese oxide batteries.

[0011] Further, the weak acid is citric acid or acetic acid, the concentration of the weak acid in the mixture is 2-5 mM, the ratio of the positive electrode powder to distilled water is 1 g: 200 mL, the water bath heating temperature is 25-90°C, the heating time is 4-12 h, and the ultrasonic treatment time is 10-60 min.

[0012] Furthermore, the amounts of the metal ion leachate, urea, and ammonium persulfate are 30 mL: 25 mM: 3 mM.

[0013] Furthermore, the hydrothermal reaction temperature is 100–200°C, the reaction time is 2–24 h, and after the reaction is completed, the electrode is obtained by cooling, washing, and drying.

[0014] Furthermore, the current collector loaded with copper oxide nanowires on the copper foam substrate is prepared by synthesizing copper oxide nanowires on the copper foam substrate by wet chemical oxidation.

[0015] The present invention also provides an electrocatalytic electrode prepared by the above method, the electrocatalytic electrode comprising a copper foam substrate and an active component modified with nickel and cobalt on a copper oxide framework.

[0016] The present invention also provides an application of the above-mentioned electrocatalytic electrode in the electrocatalytic reduction of nitrate to ammonia.

[0017] Furthermore, the electrocatalytic electrode performs the electrocatalytic reaction in an alkaline electrolyte containing nitrate ions.

[0018] Compared with the prior art, the present invention has the following advantages and technical effects: This invention utilizes a weak acid to dissolve mixed transition metal ions (primarily nickel, cobalt, and manganese) from the cathode of spent lithium-ion batteries as a metal source, and directly constructs an electrocatalytic electrode on the surface of a current collector. This achieves efficient resource utilization from "retired battery → mixed metal solution → functional catalytic electrode." The resulting catalytic electrode is applied to the electrocatalytic reduction of nitrates to ammonia, ultimately achieving a Faraday efficiency of 94% and a yield of 10.2 mmol·h⁻¹. -1 ·cm -2 The ammonia yield was improved, and the catalyst was stably catalyzed for 50 h at a current of 1 A in a flow cell without significant performance degradation. Attached Figure Description

[0019] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 The X-ray diffraction (XRD) pattern of Ni / Co-CuOx / CF prepared in Example 2; Figure 2 SEM images of Ni / Co-CuOx / CF prepared in Example 2 are shown below; where a is a low-magnification SEM image, b is a medium-magnification SEM image, and c is a high-magnification SEM image. Figure 3 The LSV curves of Ni / Co-CuOx / CF prepared in Examples 1-4 under different conditions are shown. Figure 4 The Faraday efficiency of Ni / Co-CuOx / CF prepared in Examples 1-4 under different conditions; Figure 5 The yield of NH3 of Ni / Co-CuOx / CF prepared in Examples 1-4 under different conditions; Figure 6 The Faraday efficiency and production rate of ammonia prepared by Ni / Co-CuOx / CF in Example 2 at different current densities in a flow cell; Figure 7The results of the stability test of the Ni / Co-CuOx / CF prepared in Example 2 under a current of 1A are shown. Detailed Implementation

[0020] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0021] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0022] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0023] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0024] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0025] This invention provides a method for resource recycling based on extracting metals from spent lithium-ion batteries, comprising the following steps: (1) Collection of positive electrode powder from waste lithium-ion batteries Disassemble used lithium-ion batteries (selected from one or more of high-nickel ternary lithium batteries, lithium iron phosphate batteries, lithium cobalt oxide batteries, and lithium manganese oxide batteries) and collect the positive electrode powder; (2) Preparation of metal ion leachate Take 1g of the collected positive electrode powder, add it to 200mL of distilled water, mix well to obtain a mixture; Add a weak acid (citric acid or acetic acid, for example) to the above mixture to make its final concentration in the mixture 2-5 mM (e.g. 3 mM). The mixture is heated in a water bath at a temperature of 25–90°C (e.g., 75°C) for 4–12 hours (e.g., 8 hours). After the water bath heating is completed, ultrasonic treatment is performed for 10 to 60 minutes (e.g., 40 minutes) to obtain a metal ion leachate. (3) Preparation of current collector Take a copper foam (CF) substrate (size such as 3cm×2cm) and synthesize CuO nanowires on its surface by wet chemical oxidation to obtain CuO nanowire / copper foam current collector; (4) Preparation of hydrothermal reaction precursor solution Take 30 mL of the metal ion leaching solution obtained in step (2), add 25 mM urea and 3 mM ammonium persulfate, stir evenly, and obtain the hydrothermal reaction precursor solution. (5) Hydrothermal reaction in situ growth Transfer the hydrothermal reaction precursor solution from step (4) to the reactor, and simultaneously add the current collector (CuO nanowires / copper foam) prepared in step (3). Seal the reactor and carry out the hydrothermal reaction. The reaction temperature is 100-200℃ (e.g., 120℃), and the reaction time is 2-24h (selectable as 2h, 6h, 12h, or 24h, e.g., 6h). After the reaction is completed, allow it to cool naturally to room temperature. (6) Post-processing Remove the current collector, wash it several times with distilled or deionized water, and dry it at a suitable temperature (e.g., 60°C) to obtain the final electrocatalytic electrode, named Ni / Co-CuOx / CF (where Ni and Co are from the leachate of spent batteries, and CuO is from the leaching solution of spent batteries). x (From the current collector substrate).

[0026] An electrocatalytic electrode can be prepared using the above method. By mass percentage, the electrocatalytic electrode contains 0.4-0.6% nickel, 0.2-0.3% cobalt, and the balance is copper and oxygen.

[0027] The aforementioned electrocatalytic electrode can be used in the electrocatalytic reduction of nitrate to ammonia, in which the electrocatalytic electrode performs the electrocatalytic reaction in an alkaline electrolyte containing nitrate.

[0028] Unless otherwise specified, "room temperature" in this invention refers to 25±2℃.

[0029] All raw materials and reagents used in this invention were purchased from the market.

[0030] The technical solution of the present invention will be further illustrated by the following embodiments.

[0031] Example 1 A method for resource recycling based on extracting metals from spent lithium-ion batteries includes the following steps: (1) Collection of positive electrode powder from waste lithium-ion batteries Disassemble used lithium-ion batteries (a mixture of high-nickel ternary lithium batteries and lithium cobalt oxide batteries) and collect the positive electrode powder; (2) Preparation of metal ion leachate Take 1g of the collected positive electrode powder, add it to 200mL of distilled water, mix well to obtain a mixture; add citric acid to the mixture to make its final concentration in the mixture 3mM; heat the mixture in a water bath at 75℃ for 8h; after the water bath heating is completed, perform ultrasonic treatment for 40min to obtain a metal ion leaching solution. (3) Preparation of current collector Copper foam (CF) substrates (3cm × 2cm) were cleaned sequentially with acetone and ethanol, then immersed in a mixed solution of 0.125M (NH4)2S2O8 and 2.5M NaOH at room temperature for 15 min of oxidation, then cleaned with deionized water and dried at 60℃ for 3 h to obtain Cu(OH)2 nanowires. Finally, they were calcined in a muffle furnace at a heating rate of 5℃ / min to 200℃ for 2 h to transform them into CuO nanowires (NWs), thus obtaining CuO nanowire / copper foam current collectors. (4) Preparation of hydrothermal reaction precursor solution Take 30 mL of metal ion leaching solution from step (2), add 25 mM urea and 3 mM ammonium persulfate to it, stir evenly to obtain hydrothermal reaction precursor solution; (5) Hydrothermal reaction in situ growth The hydrothermal reaction precursor liquid from step (4) was transferred to the reactor, and the CuO nanowires / foamed copper current collector prepared in step (3) was added. The reactor was sealed and the hydrothermal reaction was carried out at a temperature of 120°C for 2 hours. After the reaction was completed, the reactor was naturally cooled to room temperature. (6) Post-processing The current collector was removed, washed several times with deionized water, and dried at 60°C to obtain the final electrocatalytic electrode, named Ni / Co-CuOx / CF-2h.

[0032] Example 2 Same as Example 1, except that the hydrothermal reaction time in step (5) is adjusted to 6h, named Ni / Co-CuOx / CF-6h.

[0033] Example 3 Same as Example 1, except that the hydrothermal reaction time in step (5) is adjusted to 12h, named Ni / Co-CuOx / CF-12h.

[0034] Example 4 Same as Example 1, except that the hydrothermal reaction time in step (5) is adjusted to 24h, named Ni / Co-CuOx / CF-24h.

[0035] 1. X-ray diffraction analysis: XRD is used to test samples and capture changes in the crystal structure of the material during the reaction process. The instrument used in this invention is the Rigaku Ultima IV from Japan.

[0036] Figure 1 The image shows the X-ray diffraction pattern of the Ni / Co-CuOx / CF prepared in Example 2. As can be seen from the image, the Ni and Co metal sources were obtained from a high-nickel ternary cathode material from spent lithium-ion batteries and then extracted with mild citric acid before being used in catalyst preparation. Due to limitations in the actual composition and leaching efficiency of the spent battery cathode material, the overall Ni and Co loading was low, far below the critical content for XRD detection. Under the dominant signal of the strong crystalline phase CuO / Cu2O, the diffraction signals of the low-content Ni and Co were completely masked, and no identifiable diffraction peaks could be formed.

[0037] 2. Scanning electron microscope (SEM) image Figure 2 The images show SEM images of the Ni / Co-CuOx / CF prepared in Example 2. Images a, b, and c are SEM images of Ni / Co-CuOx / CF obtained at different magnifications. Image a is a low-magnification SEM image, showing that the sample grows uniformly and densely on the substrate surface. Image b is a medium-magnification SEM image, indicating that the array consists of a large number of interwoven one-dimensional nanowires. Image c is a high-magnification SEM image, further revealing that the surface of each individual nanowire is not smooth, but rather a loosely dispersed and rough-surfaced nanosheet structure. In summary, Ni / Co-CuOx / CF exhibits a loosely dispersed and rough-surfaced nanosheet structure.

[0038] 3. The content of metal components in the sample and the metal leaching content in the electrolyte were determined by ICP-MS analysis. The instrument used in this invention was a TJA Atomscan. The sample was the Ni / Co-CuOx / CF precursor solution prepared in Example 2 before hydrothermal reaction. The results are shown in Table 1.

[0039] Table 1 As shown in Table 1, the main metallic element in the precursor solution is copper. After dilution correction, the copper concentration in the original solution is 1.865416 mg / L, accounting for 99.2243% of the total metal content. Nickel and cobalt were also clearly detected, with concentrations of 0.889478 mg / L and 0.487246 mg / L in the original solution, corresponding to percentages of 0.4731% and 0.2592%, respectively. This indicates that nickel and cobalt were successfully introduced and uniformly dispersed in the precursor solution without hydrothermal reaction, confirming that the present invention successfully prepared nickel- and cobalt-modified Ni / Co-CuOx / CF materials.

[0040] 4. The LSV curves of the Ni / Co-CuOx / CF prepared in Examples 1-4 were determined under different conditions. Specifically, the Ni / Co-CuOx / CF samples (3cm × 2cm) were cut into 1cm × 1.5cm pieces to serve as the working electrode. An Hg / HgO electrode was used as the reference electrode, and a platinum mesh as the counter electrode. An H-type electrolytic cell was used for the test system. The electrolyte system was 1 mol·L⁻¹. -1 KOH solution and 2000ppm NO3 - A mixed solution composed of -N.

[0041] This invention employs linear sweep voltammetry (LSV) to characterize the catalytic activity of the electrode, using the Donghua Electrochemical Workstation. The test parameters were set as follows: potential range -0.4 to 0.4 V, scan rate 0.05 V·s. -1 . Figure 3 In the diagram, the dashed line represents a substance containing only 1 mol·L⁻¹ -1 KOH, NO3-free - LSV curves under -N addition conditions, with the solid line representing the addition of 2000 ppm NO3 to the working electrode side. - LSV curve under -N condition.

[0042] from Figure 3 It can be seen from this that in the absence of NO3 - In the electrolyte, Ni / Co-CuOx / CF has a lower current density and weaker HER capability, especially with the addition of NO3. - After reacting, the current density surged significantly, with the current increment in Ni / Co-CuOx / CF-6h approaching 800 mA·cm⁻¹. -2 Furthermore, it requires a more corrected cathode potential to achieve the same current density, thus exhibiting superior NO3- content. - Reduction performance.

[0043] 5. At 200~600mA·cm -2Within the current range, the Ni / Co-CuOx / CF prepared in Examples 1-4 were tested for constant current performance. Specifically, the product selectivity of the catalyst was analyzed using a chronopotentialostatic method at current ratings of 200, 300, 400, 500, and 600 mA·cm⁻¹. -2 Performance tests were conducted at different current densities, with each current density used for continuous electrolysis for 10 minutes. Before switching current densities, a certain volume of electrolyte was collected from the cathode chamber for quantitative analysis of the products.

[0044] Quantitative analysis of ammonia: Nessler's reagent spectrophotometry was used. Electrolyte sample was taken and analyzed at 0.5 mol·L⁻¹. -1 Neutralize to neutral with H2SO4, take 0.1 mL of electrolyte and dilute with deionized water to 25 mL; add 0.5 mL of 500 g·L⁻¹ electrolyte sequentially. -1 Sodium tartrate solution was thoroughly mixed with 0.5 mL of Nessler's reagent (HgI₂-KI-NaOH) and allowed to react at room temperature for 20 min. The absorbance was measured at 420 nm using a UV-Vis spectrophotometer, and the Faraday efficiency of NH₃ was calculated based on the absorbance values. Quantitative analysis of nitrite: 0.1 mL of electrolyte was diluted to 25 mL with deionized water. 1 mL of 10 mg / L aminobenzenesulfonic acid solution and 1 mL of N-(1-naphthyl)ethylenediamine hydrochloride solution were added sequentially. After thorough mixing, the solution was allowed to stand at room temperature for 20 minutes for color development. The absorbance was measured at 540 nm using a UV-Vis spectrophotometer (National Standard HJ 535-2009). The Faradaic efficiency of nitrogen in nitrite was calculated using the absorbance, and the sum of the two values ​​was the total Faradaic efficiency.

[0045] Figure 4 The figures show the Faradaic efficiencies of the Ni / Co-CuOx / CF prepared in Examples 1-4 under different conditions. As can be seen from the figures, under different currents, the activity of Ni / Co-CuOx / CF-6h for the synthesis of NH3 is higher than that of the other three catalyst samples.

[0046] 6. The Ni / Co-CuOx / CF prepared in Examples 1-4 were applied to the electrocatalytic reduction of nitrate to synthesize ammonia, and the yield of NH3 was calculated. The specific method was as follows: electrolyte samples were collected from the cathode chamber, the ammonia concentration was determined by the Nessler's reagent spectrophotometric method, and the yield of NH3 was calculated based on the absorbance.

[0047] Figure 5 The yield of NH3 in Ni / Co-CuOx / CF prepared in Examples 1-4 under different conditions was determined by the following method: Figure 5 As can be seen, the NH3 yield is highest at a current of 600 mA, especially in Ni / Co-CuOx / CF-6h, reaching 2.7 mmol·h⁻¹.-1 ·cm -2 ,correspond Figure 4 The Faraday efficiency (FE) in this study is 97.8%.

[0048] 7. The Faradaic efficiency and production rate of ammonia prepared by Ni / Co-CuOx / CF in Example 2 were tested in a flow cell at different current densities. The specific method was as follows: an iridium mesh was used as the counter electrode, and an Hg / HgO electrode was used as the reference electrode. An anion exchange membrane was used to separate the anode and cathode chambers. The electrolyte composition was 1M KOH and 0.1M NO3. - An alkaline solution was continuously pumped into the anode and cathode chambers using a peristaltic pump, and the Faraday efficiency and yield of ammonia were tested at different current densities.

[0049] Figure 6 The figure shows the Faradaic efficiency and production rate of ammonia produced by the Ni / Co-CuOx / CF prepared in Example 2 at different current densities in a flow cell. It can be seen from the figure that, in the presence of 0.1 M NO3... - In the electrolyte, Ni / Co-CuO / CF exhibited a Faradaic efficiency of 94% at 1A and 10.2 mmol·h⁻¹ at 3A. -1 ·cm -2 The ammonia yield increased, but the corresponding Faraday efficiency decreased.

[0050] 8. The Ni / Co-CuOx / CF prepared in Example 2 was placed in a flow cell, and stability tests were conducted while maintaining a current of 1A. Specifically, the stability of the catalyst was analyzed using a chronopotential method under constant current conditions. A constant current of 1A was applied throughout the entire process, and continuous electrolysis was performed at room temperature and pressure for 50 hours. During the test, the changes in the working electrode potential were recorded in real time, and quantitative samples of NH3 and NO2 in the electrolyte were taken at fixed intervals for detection. - The product concentration was measured, and the stability and Faraday efficiency of the catalytic reaction were monitored in real time.

[0051] Figure 7 The figure shows the stability test results of Ni / Co-CuOx / CF prepared in Example 2 under a current of 1A. As can be seen from the figure, Ni / Co-CuOx / CF remains stable after 50 hours of electrolysis.

[0052] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for resource recycling based on extracting metals from spent lithium-ion batteries, characterized in that, Includes the following steps: The positive electrode powder collected from waste lithium-ion batteries, distilled water, and weak acid are mixed evenly, and the resulting mixture is subjected to water bath heating and ultrasonic treatment to obtain a metal ion leachate. The metal ion leachate is mixed with urea and ammonium persulfate and transferred to a reactor containing a current collector for hydrothermal reaction, thereby growing an electrocatalytic electrode in situ on the surface of the current collector. The current collector is a current collector on a copper foam substrate loaded with copper oxide nanowires.

2. The method for resource recycling based on extracting metals from spent lithium-ion batteries according to claim 1, characterized in that, The waste lithium-ion batteries are selected from one or more of the following: waste high-nickel ternary lithium batteries, waste lithium iron phosphate batteries, waste lithium cobalt oxide batteries, and waste lithium manganese oxide batteries.

3. The method for resource recycling based on extracting metals from spent lithium-ion batteries according to claim 1, characterized in that, The weak acid is citric acid or acetic acid, the concentration of the weak acid in the mixture is 2-5 mM, and the ratio of the positive electrode powder to distilled water is 1 g: 200 mL.

4. The method for resource recycling based on extracting metals from spent lithium-ion batteries according to claim 1, characterized in that, The water bath heating temperature is 25–90°C, and the heating time is 4–12 h; the ultrasonic treatment time is 10–60 min.

5. The method for resource recycling based on extracting metals from spent lithium-ion batteries according to claim 1, characterized in that, The amounts of the metal ion leachate, urea, and ammonium persulfate are 30 mL: 25 mM: 3 mM.

6. The method for resource recycling based on extracting metals from spent lithium-ion batteries according to claim 1, characterized in that, The hydrothermal reaction is carried out at a temperature of 100–200°C for 2–24 hours. After the reaction is completed, the electrode is obtained by cooling, washing, and drying.

7. The method for resource recycling based on extracting metals from spent lithium-ion batteries according to claim 1, characterized in that, The method for preparing the current collector loaded with copper oxide nanowires on the copper foam substrate is as follows: copper oxide nanowires are synthesized on the copper foam substrate by wet chemical oxidation.

8. An electrocatalytic electrode prepared by the method according to any one of claims 1 to 7.

9. The application of the electrocatalytic electrode as described in claim 8 in the electrocatalytic reduction of nitrate to ammonia.

10. The application according to claim 9, characterized in that, The electrocatalytic electrode performs the electrocatalytic reaction in an alkaline electrolyte containing nitrates.

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