Method for preparing high-performance electrolytic water oxygen evolution reaction catalyst from plasma-treated waste lithium-ion battery cathode black powder

Abstract

The present application relates to a method for preparing a high-performance water electrolysis oxygen evolution reaction catalyst from plasma-treated spent lithium-ion battery positive black powder, comprising the following steps: collecting the spent positive material of a spent lithium-ion battery as spent black powder after separating the spent positive material from the current collector, and then loading it on a self-supporting substrate to prepare a pre-catalyst electrode; performing plasma treatment on the prepared pre-catalyst electrode in a low-pressure gas atmosphere; and in-situ reconstructing the obtained modified pre-catalyst electrode into a high-performance water electrolysis oxygen evolution reaction catalyst working electrode under alkaline water electrolysis conditions, while dissolving out the remaining lithium ions in the reconstructed structure. Compared with the prior art, the method of the present application upgrades the retired positive material to a high-performance transition metal water electrolysis catalyst through simple process steps and lower cost, while realizing the recycling of lithium ions.

Description

Technical Field

[0001] This invention relates to the field of interdisciplinary technology of resource recycling and new energy materials, and in particular to a method for preparing high-performance catalysts for oxygen evolution reaction in water electrolysis using plasma-treated waste lithium-ion battery cathode black powder. Background Technology

[0002] With the rapid growth in demand for lithium-ion batteries from mobile terminals, electric vehicles, and grid energy storage, the number of retired batteries is increasing exponentially, making their resource utilization and environmental pollution issues urgent challenges. Currently, the recycling of spent lithium-ion batteries mainly relies on traditional processes such as hydrometallurgy and pyrometallurgy. While these methods can recover some valuable metals, they generally suffer from high energy consumption, the need for highly corrosive acid and alkali reagents, and cumbersome metal separation processes. More importantly, these processes completely destroy the intrinsic structure of the cathode material, making it difficult to reuse it directly as a functional precursor, resulting in limited added value of the final product and failing to achieve high-value recycling of resources. Therefore, developing economical and environmentally friendly waste battery recycling technologies to achieve high-value reuse of material components is of great significance for ensuring resource security, promoting a circular economy, and protecting the ecological environment.

[0003] Among various lithium-ion batteries, those using oxide cathode materials (such as ternary lithium nickel cobalt manganese NCM and lithium cobalt oxide LCO) occupy a significant market share and are widely used in electric vehicles and energy storage systems. Meanwhile, water electrolysis for hydrogen production is considered a way to obtain "green hydrogen." The bottleneck of this technology lies in the oxygen evolution reaction (OER), whose kinetics are slow and currently heavily reliant on noble metal-based catalysts (such as IrO2 and RuO2). However, the scarcity and high cost of noble metals limit their large-scale industrial application. It is worth noting that transition metal oxide cathode materials and OER catalysts share a high degree of similarity in their active components (both are based on transition metals such as Ni, Co, and Mn). Therefore, the former is considered a potential alternative to noble metal catalysts, but its intrinsic catalytic activity still needs improvement. Studies have shown that oxide cathode materials undergo crystal structure reconstruction and lithium-ion dissolution under alkaline environments and specific applied voltages. If this characteristic can be utilized to directly convert retired cathode materials into high-value-added oxygen evolution reaction electrocatalysts, and simultaneously recover the scarce lithium resources within them, then "turning waste into treasure" and "treating waste with waste" can be achieved.

[0004] Existing research indicates that oxygen evolution reaction (OER) catalysts undergo a certain degree of remodeling under operating conditions, and defect engineering is an effective method for inducing this remodeling. Applying defect engineering to decommissioned oxide cathode materials holds promise for upgrading and recycling them into high-performance OER catalysts by inducing controllable in-situ structural remodeling under operating conditions. However, a convenient and feasible method for precisely applying this method to decommissioned cathode materials and achieving their directional conversion into high-performance catalysts remains lacking. Furthermore, multimetallic compound catalysts possess superior OER activity due to the synergistic effect of metal active sites. Therefore, supplementing decommissioned oxide cathode materials with specific metal sites (such as iron for ternary lithium) holds promise for further enhancing their electrocatalytic activity. However, current synthesis processes for multimetallic compound catalysts are often cumbersome and energy-intensive, making it difficult to meet the demand for low-cost upgrading and recycling of decommissioned cathode materials.

[0005] In summary, existing technologies lack a method that can effectively enhance the catalytic performance of decommissioned oxide materials in the oxygen evolution reaction and simultaneously achieve efficient lithium recovery. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing a high-performance oxygen evolution reaction catalyst for water electrolysis using plasma-treated waste lithium-ion battery cathode black powder. This method recovers cathode black powder material from waste lithium-ion batteries and converts it into a high-performance oxygen evolution reaction catalyst for water electrolysis, while simultaneously extracting lithium efficiently. The invention first introduces additional active sites into the retired cathode material catalyst (waste black powder) based on a specific self-supporting substrate; then, it treats the pre-catalyst electrode using non-thermal equilibrium plasma technology; subsequently, it performs electrochemical activation under alkaline water electrolysis conditions, inducing controllable in-situ structural reconstruction. The reconstructed structure is further modified using the activation process on the self-supporting substrate, simultaneously achieving the generation of a highly active heterostructure and the selective dissolution of residual lithium ions, thus preparing a high-performance oxygen evolution reaction catalyst for water electrolysis.

[0007] The objective of this invention can be achieved through the following technical solutions: The first objective of this invention is to provide a method for preparing a high-performance oxygen evolution reaction catalyst for water electrolysis using plasma-treated waste lithium-ion battery cathode black powder, the method comprising the following steps: (1) The waste positive electrode material of the waste lithium-ion battery is separated from the current collector and collected as waste black powder (retired positive electrode material powder). The waste black powder is loaded onto a self-supporting substrate to prepare a pre-catalyst electrode. (2) The precatalyst electrode obtained in step (1) is modified by low-pressure non-thermal equilibrium plasma to obtain a plasma-modified precatalyst electrode. (3) The plasma-modified precatalyst electrode obtained in step (2) is electrochemically activated in an alkaline electrolyte system, so that the plasma-modified precatalyst electrode is reconstructed in situ into a high-performance working electrode for the oxygen evolution reaction catalyst of water electrolysis, and the residual lithium ions in the waste black powder (retired cathode material powder) are dissolved simultaneously.

[0008] Further, in step (1), the waste lithium-ion battery after recycling (i.e. waste lithium-ion battery) is disassembled and the positive electrode sheet (i.e. positive electrode waste) is taken out after being fully discharged. After being cleaned with organic solvent, the positive electrode material and current collector in the positive electrode sheet are separated. The obtained positive electrode material is dried and ground to obtain retired positive electrode material powder (i.e. waste black powder).

[0009] Further, in step (1), the process of separating the waste positive electrode material of the waste lithium-ion battery from the current collector and collecting it as waste black powder includes the following steps: completely discharging and disassembling the waste lithium-ion battery to obtain the positive electrode sheet; cleaning the by-reaction products and residual lithium salt electrolyte on the surface of the positive electrode sheet with an organic solvent (such as dimethyl carbonate); separating the active material and current collector in the positive electrode sheet by means such as hot water soaking; then drying and grinding the obtained active material; collecting the positive electrode material powder and washing it with an organic solvent such as N-methylpyrrolidone (to remove the binder polyvinylidene fluoride PVDF), drying, and grinding to obtain the retired positive electrode material powder, which is the waste black powder.

[0010] Furthermore, in step (1), the waste black powder is one or more of ternary lithium (nickel cobalt manganese NCM), lithium manganese oxide, and lithium cobalt oxide.

[0011] Further, in step (1), the self-supporting substrate is one or more of foam metal, foam metal alloy, carbon paper, carbon felt, etc.

[0012] Furthermore, the foam metal is selected from one or more of foam nickel, foam iron, foam cobalt, etc.

[0013] Furthermore, the foam metal alloy is selected from one or more of foam nickel-iron alloys, foam stainless steel, foam iron-manganese alloys, etc.

[0014] More preferably, the self-supporting substrate is a foamed nickel-iron alloy.

[0015] Furthermore, in step (1), the process of loading waste black powder onto a self-supporting substrate to prepare a pre-catalyst electrode includes the following steps: The waste black powder, conductive agent, and binder are mixed and dispersed evenly in a solvent to obtain a dispersion. The dispersion is then loaded onto a self-supporting substrate to obtain a pre-catalyst electrode.

[0016] Furthermore, the loading method can be drop application, spin coating, etc.

[0017] Furthermore, the mass ratio of waste black powder to conductive agent is (1:4)-(4:1).

[0018] Furthermore, the solvent is selected from one or more of ethanol, water, isopropanol, tetrahydrofuran, etc.

[0019] Furthermore, the adhesive is selected from one or more of Nafion (5 wt%) solution, polytetrafluoroethylene (PTFE), etc.

[0020] Furthermore, the conductive agent is selected from one or more of Vulcan Carbon, acetylene black, Ketjen black, etc.

[0021] Furthermore, in step (1), the pre-catalyst electrode preparation step can be adjusted to be before or after plasma treatment according to actual needs. Specifically, the plasma-treated particles can be prepared as pre-catalyst electrodes, or the particles can be prepared as pre-catalyst electrodes and then subjected to plasma treatment.

[0022] Furthermore, in step (2), during the low-pressure non-thermal equilibrium plasma modification process, non-thermal equilibrium plasma is used, and the non-thermal equilibrium plasma is selected from one or more of microwave plasma, radio frequency plasma, DC plasma, intermediate frequency plasma, dielectric barrier plasma, glow plasma or corona plasma.

[0023] Further, in step (2), during the low-pressure non-thermal equilibrium plasma modification process, the total gas flow rate is 40~100 standard milliliters per minute, the plasma discharge environment pressure is 10~150 Pa, the discharge power is 100~500W, and the plasma treatment time is 1~10 min; the plasma discharge atmosphere is selected from one or more of argon, hydrogen, nitrogen, etc.

[0024] Furthermore, in step (3), the plasma-modified pre-catalyst electrode is activated and reconstructed as a high-performance working electrode for the oxygen evolution reaction catalyst in water electrolysis under alkaline electrolyte conditions, and the residual lithium ions in the decommissioned cathode material are dissolved simultaneously.

[0025] Furthermore, the alkaline electrolyte operating condition is the alkaline water electrolysis operating condition.

[0026] Furthermore, in step (3), the electrochemical activation is one of constant current treatment, constant voltage treatment, or cyclic voltammetry treatment.

[0027] Furthermore, when using constant current processing, a current density of 5~1000 mA·cm is applied to the working electrode. -2 .

[0028] Furthermore, when using constant voltage processing, an external voltage of 1.3~1.8 V vs. RHE is applied to the working electrode.

[0029] Furthermore, when using cyclic voltammetry, the cyclic range was 1.0 V to 1.6–2.0 V vs. RHE, and the scan rate was 1–200 mV·s. 1 .

[0030] Furthermore, in step (3), the lithium ions remaining in the plasma-modified pre-catalyst electrode are simultaneously dissolved to obtain an alkaline electrolyte rich in lithium ions.

[0031] Further, after step (3), the following step (4) is performed: The alkaline electrolyte rich in lithium ions from step (3) is collected, enriched by reflux, concentrated by evaporation, and then a precipitant is added to crystallize the lithium ions in the form of lithium salts, thereby achieving the extraction of lithium elements.

[0032] Furthermore, step (4) specifically includes the following steps: (4-1) Collect the alkaline electrolyte rich in lithium ions from step (3) and reflux to separate the recovery liquid rich in lithium ions; (4-2) The lithium-ion-rich recovery liquid collected by evaporation and concentration is used to improve the efficiency of lithium extraction, and a concentrated lithium-containing recovery liquid is obtained. (4-3) Add recrystallization additives to the concentrated lithium-containing recovery liquid to precipitate lithium ions into lithium salts and achieve the extraction of lithium elements.

[0033] Furthermore, step (4) specifically includes the following steps: The lithium-ion-rich alkaline electrolyte is extracted through the electrolyte reflux system of the alkaline water electrolysis cell, and the lithium-ion fraction is separated from the alkaline KOH electrolyte by circulation enrichment. The extraction of lithium ions in the reflux liquid is accelerated by evaporating the solvent. A recrystallization additive is added to the lithium-ion-rich recovery liquid to precipitate the lithium ions into lithium salts, thus extracting lithium. The recrystallization additive reacts chemically with the lithium ions in the solution to form a lithium-containing precipitate that is poorly soluble in water. After filtration, the lithium-containing recrystallized product is obtained.

[0034] Furthermore, in step (4), the lithium-ion-rich alkaline electrolyte is enriched and separated from the alkaline electrolyte working medium during the electrolyte reflux operation of the alkaline electrolytic cell. The enrichment methods can be one or more of the following: membrane separation method, electrodialysis method, etc.

[0035] Furthermore, in step (4), the precipitant is one or more of carbonates, hydroxides, sulfates, etc.

[0036] The second objective of this invention is to provide a high-performance water electrolysis oxygen evolution reaction catalyst, which is prepared using the method described above for preparing high-performance water electrolysis oxygen evolution reaction catalyst using plasma-treated waste lithium-ion battery cathode black powder.

[0037] Furthermore, the high-performance water electrolysis oxygen evolution reaction catalyst is an electrocatalyst based on recycled waste lithium-ion battery cathode materials.

[0038] Furthermore, the high-performance water electrolysis oxygen evolution reaction catalyst can be used for the electrocatalytic decomposition of water to produce oxygen.

[0039] This invention relates to a method for preparing a high-performance oxygen evolution reaction catalyst for water electrolysis by recycling waste lithium-ion battery cathode powder. The method includes the following steps: separating waste cathode material from a current collector and collecting it as waste black powder, which is then loaded onto a self-supporting substrate to prepare a pre-catalyst electrode; subjecting the prepared pre-catalyst electrode to plasma treatment under a low-pressure gas atmosphere; reconstructing the obtained modified pre-catalyst electrode in situ into a high-performance oxygen evolution reaction catalyst working electrode under alkaline water electrolysis conditions, while simultaneously dissolving the remaining lithium ions within the reconstructed structure; and refluxing and enriching the lithium-containing alkaline water from the previous step, followed by purification and crystallization to obtain a lithium-containing product. By introducing specific active sites into the retired cathode catalyst through a self-supporting substrate, the heterostructure generated by plasma treatment-induced reconstruction of the retired cathode material significantly improves the catalytic performance compared to the original retired cathode material (waste cathode material from waste lithium-ion batteries). Compared with existing technologies, the method of the present invention effectively reduces the use of chemical reagents, and through simple process steps and low cost, upgrades and recycles retired cathode materials into high-performance transition metal water electrolysis catalysts, while realizing the recovery of lithium ions and further reuse.

[0040] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention provides a novel, simple, low-cost method for upgrading and recycling battery materials suitable for industrial production, which does not require long-term high-temperature pyrometallurgical reactions or hydrometallurgical reactions involving large amounts of acid and alkali reagents. The non-thermal equilibrium plasma modification technology used in this invention is a dry gas treatment process that does not require the use of strong acids and alkalis. It has the advantages of low energy consumption, short processing time, and environmental friendliness, and avoids the secondary pollution problems caused by traditional hydrometallurgy.

[0041] (2) The method provided by this invention can recycle and reuse lithium, manganese, cobalt, and nickel elements in decommissioned oxide cathode materials, and introduce additional active sites through a self-supporting substrate, avoiding the energy consumption of repeated mining and saving resources. The high-performance working electrode of the water electrolysis oxygen evolution reaction catalyst with an active structure, which is finally reconstructed in situ after plasma treatment, has a significantly improved catalytic effect on water electrolysis oxygen evolution reaction compared to using the recovered cathode black powder directly as a catalyst. Moreover, its performance is superior to commercial precious metal electrocatalysts, with better water electrolysis catalytic properties and stability. It can effectively improve the efficiency of oxygen evolution reaction, and is easy to operate and scale up, significantly improving the economic benefits of waste lithium-ion battery recycling.

[0042] (3) This invention achieves high performance of the catalyst for the oxygen evolution reaction in water electrolysis while efficiently dissolving high-value lithium elements from waste cathode materials by performing in-situ reconstruction of the pre-catalyst and lithium dissolution in the same process. High-value, high-quality pure lithium compounds can be obtained after simple subsequent purification. This realizes the comprehensive utilization of resources and the efficient conversion of energy, and has important economic and environmental significance. Attached Figure Description

[0043] Figure 1 Electron paramagnetic resonance (EPR) spectra of the s-NCM prepared in Example 1 of this invention before and after plasma treatment, and the CV curve of the oxygen evolution reaction (OER) at the working electrode (after reconstruction). (a) Electron paramagnetic resonance (EPR) spectra; (b) OER CV curve.

[0044] Figure 2 Figure 1 shows the HR-TEM and HAADF spectra of the active particles on the s-NCM / CP-Ar working electrode prepared in Example 1 of this invention. (a) and (b) are the bright-field phases of the active particles at different magnifications; (c) and (d) are the fast Fourier transform spectra of the corresponding crystal structure lattice fringes; Figure (e) shows the dark-field phase based on HAADF, and the corresponding elemental analysis spectra (f) for Mn, (g) for Ni, and (h) for Co.

[0045] Figure 3 The oxygen evolution reaction (OER) CV test diagrams of the reconstructed working electrode prepared in Example 2 of this invention and the OER CV test diagram of the unloaded self-supporting substrate INF are shown.

[0046] Figure 4 This is a CV test diagram of the oxygen evolution reaction of the reconstructed working electrode prepared based on s-LCO in Example 4 of the present invention.

[0047] Figure 5 This is a CV test diagram of the oxygen evolution reaction of the reconstructed working electrode prepared based on s-LMO in Example 5 of the present invention.

[0048] Figure 6 These are in-situ XRD patterns of the (reconstructed) working electrodes prepared in Example 1 and Comparative Example 1 of this invention under alkaline oxygen evolution reaction. (a) shows s-NCM / CP-Ar, and (b) shows s-NCM / CP. The external voltage indicator on the right represents the voltage under the Hg / HgO electrode.

[0049] Figure 7 The oxygen evolution reaction (CV) test diagrams are shown for the working electrodes (reconstructed) prepared in Examples 1 and 2 of this invention and Comparative Example 1.

[0050] Figure 8 The oxygen evolution reaction (CV) test diagrams are shown for the (reconstructed) working electrodes prepared in Examples 1, 1, and 2 of this invention.

[0051] Figure 9 The oxygen evolution reaction (CV) test diagrams are shown for the (reconstructed) working electrodes prepared in Example 1 and Comparative Example 3 of this invention. Detailed Implementation

[0052] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments. It should be understood that the accompanying drawings and the following embodiments are for illustrative purposes only and are not intended to limit the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0053] Any value in the numerical range disclosed in this invention is not limited to the precise range or value. These ranges or values ​​should be understood to include values ​​close to these ranges or values. The endpoint values ​​of each range, the endpoint values ​​of each range and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0054] Preparation methods, materials, structures, or composition ratios not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0055] Steps not specified will be performed according to standard procedures. All reagents and instruments used are readily available and commercially available products, and the technical terminology employed conforms to general industry standards.

[0056] The following plasma treatment was performed in the ZH series RF PECVD plasma material workstation of Zhejiang Zhehe Instrument Materials Technology Co., Ltd.

[0057] The carbon paper used in the electrode fabrication process was purchased from Suzhou Shengernuo Technology Co., Ltd., the foamed nickel-iron alloy was purchased from Quanzhou Yunzongcheng New Material Co., Ltd., the conductive agent used was Vulcan Carbon (purchased from Cabot, model XC 72), and the binder Nafion solution was purchased from DuPont, USA.

[0058] The following alkaline environment catalytic oxygen evolution reaction tests were conducted on a CHI760 electrochemical workstation, and all were illustrated using a three-electrode system. The electrolyte was a 1M KOH solution, a commercial platinum sheet electrode was used as the counter electrode, a mercury / mercury oxide (Hg / HgO) electrode was used as the reference electrode, and the final sample prepared in the examples (or comparative examples) was used as the working electrode.

[0059] Example 1 This embodiment provides a method for preparing a high-performance catalyst for the oxygen evolution reaction of water electrolysis using plasma-treated waste lithium-ion battery cathode black powder, including the following steps: (1) Material Acquisition and Pretreatment: The positive electrode strips of the disassembled and completely self-discharged waste NCM batteries (nickel-cobalt-manganese ternary lithium) were cleaned with dimethyl carbonate, then immersed in hot water at 95°C for 10 seconds, and manually peeled off and collected. The separated positive electrode material was collected and washed with N-methylpyrrolidone to remove residual PVDF. After drying, it was ground with an agate mortar to obtain the retired NCM positive electrode material (s-NCM).

[0060] (2) Electrode preparation: The obtained decommissioned NCM cathode material (s-NCM), conductive agent Vulcan Carbon, and binder (Nafion (5 wt%)) were uniformly dispersed in a solvent (tetrahydrofuran) to obtain a dispersion. The mass ratio of s-NCM to conductive agent was 1:2.33. The dispersion was a mixture of s-NCM, Vulcan Carbon, tetrahydrofuran, and Nafion (5 wt%) solutions, with a volume ratio of tetrahydrofuran to Nafion (5 wt%) of 1:0.05. Further, the dispersion was dropwise added to an active area of ​​1*1 cm². 2 On a carbon paper electrode (in this embodiment, a carbon paper electrode is used as a self-supporting substrate, i.e., CP), a catalyst loading of 255 μg·cm⁻¹ was obtained. -2 The precatalyst electrode for the oxygen evolution reaction of water electrolysis is s-NCM / CP.

[0061] (3) Plasma modification treatment: The s-NCM / CP obtained in the electrode preparation step was placed in a vacuum chamber and treated with radio frequency plasma. The plasma parameters were: discharge pressure in the chamber 100 Pa, total argon flow rate 40 standard milliliters per minute, discharge power 100 W, and plasma treatment time 5 minutes. The modified pre-catalyst electrode was named s-NCM / CP-Ar.

[0062] (4) Electrochemical activation and lithium dissolution: The prepared plasma-modified precatalyst electrode was assembled into a three-electrode system. Cyclic voltammetry (oxygen evolution reaction test in alkaline environment) was used to test the assembled three-cell system in an electrolytic cell. The voltage range applied to the working electrode was 1.1-1.7 V vs. RHE, and the scan rate was 10 mV·s. -1 Stable catalytic performance for the oxygen evolution reaction in water electrolysis was obtained. The reconstructed working electrode is the working electrode of the high-performance oxygen evolution reaction catalyst for water electrolysis.

[0063] See Figure 1 (a) Electron paramagnetic resonance (EPR) spectroscopy revealed that the area of ​​the oxygen vacancy characteristic integrated peak in the modified material after Ar plasma treatment increased by 116.6% compared to the original s-NCM, indicating a significant increase in oxygen vacancy concentration. This demonstrates the effectiveness of plasma treatment in introducing defects into the material. See also Figure 1 (b) s-NCM / CP treated with Ar plasma (s-NCM / CP-Ar), under OER conditions at 10 mA·cm -2 The overpotential improved from 358 mV to 275 mV, demonstrating the role of oxygen vacancies in enhancing catalyst activity.

[0064] See Figure 2 After cyclic voltammetry testing, the oxygen evolution reaction active structure of the s-NCM / CP-Ar working electrode was observed under a high-resolution transmission electron microscope. It was found that the Ni(Co,Mn)O2\γ-Ni(Co,Mn)OOH structure obtained after Ar plasma treatment of the s-NCM was composed of stacked two-dimensional thin sheets with uniform morphology. Figure 2 As can be seen from (b), 2(c) and 2(d), the material consists of an inner layer of Ni(Co,Mn)O2 and an outer layer of Ni(Co,Mn)OOH. The two components are connected by crystal plane (003) and crystal plane (102) to form a composite heterojunction structure. Figure 2 (e) HAADF elemental energy spectrum corresponding to region Figure 2 Mn, Ni, and Co elements are uniformly distributed in (f), 2(g), and 2(h).

[0065] Example 2 Compared to Example 1, all other parts are the same, except that a foamed nickel-iron alloy (INF) is used as a self-supporting substrate in the electrode preparation step. The working electrode prepared by Ar plasma treatment in this example is named s-NCM / INF-Ar. See [link to electrochemical performance section]. Figure 3 The electrocatalytic activity of Example 2 was found to be significantly stronger than that of Example 1 and the self-supporting substrate (INF), exhibiting superior electrochemical performance. This is due to the synergistic effect between the self-supporting substrate and the plasma-treated s-NCM during the reconstruction process. Specifically, the foamed nickel-iron alloy self-supporting substrate (INF) itself provides an iron- and nickel-ion-rich local environment for the reconstruction structure of Ni(Co,Mn)O2\γ-Ni(Co,Mn)OOH supported on it during the alkaline oxygen evolution reaction. This suppresses the dissolution of active nickel species while introducing iron active sites into the oxygen evolution reaction catalyst, thereby greatly improving the overall catalytic activity of the working electrode. Previous studies have shown that introducing transition metal sites that are not originally present in catalysts based on transition metals such as Ni, Co, and Mn can further optimize the adsorption structure and reaction energy barrier of water oxidation intermediates by modifying the electronic structure of the active surface, thereby promoting the improvement of catalyst activity. This invention achieves further modification of the catalyst by using the active elements of the self-supporting substrate, which demonstrates the importance of selecting a specific self-supporting substrate in this invention.

[0066] Example 3 This embodiment is used to verify the applicability of the technical route adopted in this invention to different retired cathode materials. Compared with Example 1, all other parts are the same, except that the raw material acquisition step uses retired LiCoO2 (s-LCO) cathode material (purchased from Zhengzhou Guojuan Trading Co., Ltd.) and retired LiMn2O4 (s-LMO) cathode material (Putian Lili New Energy Technology Co., Ltd.) recycled from the battery industry, instead of retired cathode materials obtained in the laboratory. Furthermore, the electrode preparation step uses foamed nickel-iron alloy (INF) as a self-supporting substrate to prepare the corresponding pre-catalyst electrodes for the oxygen evolution reaction in water electrolysis, s-LCO / INF and s-LMO / INF. These pre-catalyst electrodes, after Ar plasma treatment, are named s-LCO / INF-Ar and s-LMO / INF-Ar. The electrochemical performance is shown in Figures 4 and 5. It can be seen that the electrocatalytic activity of the sample after plasma treatment is significantly stronger than that of the sample without plasma treatment, which demonstrates the applicability of this invention to different retired cathode materials.

[0067] Example 4 This embodiment follows Embodiment 2, specifically illustrating the synergistic process of electrolyte reflux and lithium-ion extraction in the technical route described in this invention. Based on the batch-produced s-NCM / INF-Ar working electrode prepared in Embodiment 2, it is placed in the electrolyzer system for hydrogen production, during which efficient and selective leaching of residual lithium ions is simultaneously achieved.

[0068] The deposited lithium ions are carried by the circulating KOH electrolyte into the system's concentration chamber. A membrane stack composed of monovalent cation selective exchange membranes is installed between the inlet and outlet of this concentration chamber, with a dual-electrode system consisting of graphite electrodes on both sides of the membrane stack. By applying a constant voltage to this system, potassium ions (KOH) with smaller hydration radii are induced to competitively migrate within the membrane stack, effectively blocking the passage of lithium ions (LiOH) and achieving selective enrichment of lithium ions within the concentration chamber.

[0069] After the enrichment process is completed within the predetermined time, the lithium-rich alkaline mother liquor in the concentration chamber is collected and concentrated by evaporation to achieve a lithium concentration of 60 g·L⁻¹. -1 To improve subsequent lithium recovery efficiency, under continuous stirring conditions (200-300 rpm, 95℃), the solution was reacted at a rate of 1-5 mL / min. -1 A saturated sodium carbonate solution is added dropwise to the concentrate at a rate of [missing information], and the reaction is carried out for 2 hours, causing lithium ions to precipitate as lithium carbonate. Finally, after filtration, washing, and drying, the final lithium carbonate product is obtained, thus completing the efficient extraction from electrolyte to lithium product.

[0070] Comparative Example 1 This comparative example provides a method for preparing a catalyst for the oxygen evolution reaction in water electrolysis.

[0071] Compared with Examples 1 and 2, all other parts are the same except that the argon plasma treatment is omitted. That is, the recovered retired cathode material is directly prepared into working electrodes (s-NCM / CP and s-NCM / INF) based on the corresponding self-supporting substrate for the water electrolysis oxygen evolution reaction, which is the catalyst for the water electrolysis oxygen evolution reaction.

[0072] See Figure 6(a) and (b) show that the s-NCM / CP prepared in Comparative Example 1 and the s-NCM / CP-Ar prepared in Example 1 were subjected to in-situ XRD tests in a three-electrode system under voltage step method conditions. It can be seen that in 1M KOH, s-NCM / CP undergoes sequential transformation from NCM layered oxide to β-Ni(Co,Mn)OOH and then to γ-Ni(Co,Mn)OOH with increasing voltage, with the final active structure being γ-Ni(Co,Mn)OOH. Notably, s-NCM / CP-Ar only undergoes transformation from NCM layered oxide to Ni(Co,Mn)O2\γ-Ni(Co,Mn)OOH charge-compensated heterojunctions with increasing voltage, with the final active structure being Ni(Co,Mn)O2\γ-Ni(Co,Mn)OOH.

[0073] Figure 7 To investigate the activity of the oxygen evolution reaction of the working electrodes s-NCM / CP-Ar, s-NCM / INF-Ar, s-NCM / INF, and s-NCM / CP prepared in Examples 1, 2, and Comparative Example 1, the results are shown in the figure. At a current density of 10 mA·cm⁻¹, -2 The overpotentials were 275 mV, 238 mV, 258 mV, and 358 mV, respectively. The performance data shows that even with differences in elemental composition and material structure due to variations in the self-supporting substrate of the working electrode, the pre-catalyst electrode treated with argon plasma generally exhibits higher oxygen evolution reaction activity after being reconstructed as the working electrode in an alkaline water electrolysis environment. This demonstrates the importance of this invention in using plasma discharge to introduce material defects, thereby achieving highly active structural reconstruction.

[0074] Comparative Example 2 This comparative example provides a method for preparing a catalyst for the oxygen evolution reaction in water electrolysis.

[0075] Compared with Example 1, all other parts are the same, except that the plasma atmosphere is changed to oxygen, that is, oxygen plasma treatment is used, named s-NCM / CP-O2, which is the pre-catalyst electrode for the oxygen evolution reaction of water electrolysis.

[0076] Figure 8 To investigate the activity of the oxygen evolution reaction after the s-NCM / CP-Ar, s-NCM / CP, and s-NCM / CP-O2 prepared in Examples 1, 1, and 2 were reconstructed as working electrodes, a current density of 10 mA·cm⁻¹ was used. -2The overpotentials were 275 mV, 358 mV, and 330 mV, respectively. The performance data shows that even based on the same material, s-NCM materials treated with different plasma atmospheres exhibit different oxygen evolution reaction activities in an alkaline water electrolysis environment. This highlights the importance of this invention in using reducing plasma discharge to introduce material defects, thereby achieving directional reconstruction of highly active structures.

[0077] Comparative Example 3 This comparative example provides a method for preparing a catalyst for the oxygen evolution reaction in water electrolysis. The powdered s-NCM prepared using step (1) of Example 1 was subjected to plasma treatment to obtain the modified material s-NCM-Ar. s-NCM-Ar was prepared into a dispersion and dropped onto a CP in the same manner as in Example 1, thus forming the modified pre-catalyst electrode s-NCM-Ar / CP. Figure 9 As can be seen, at a current density of 10 mA·cm -2 At that time, the overpotentials for s-NCM / CP-Ar, s-NCM-Ar / CP, and s-NCM / CP were 275 mV, 318 mV, and 358 mV, respectively. It can be seen that the performance of s-NCM-Ar / CP is inferior to that of s-NCM / CP-Ar, which was first prepared as an electrode and then subjected to Ar plasma treatment, but it is still superior to s-NCM / CP without any plasma treatment. This may be because the oxygen vacancies in s-NCM-Ar interact with the surrounding environment during the preparation of the electrode dispersion, partially losing their original effect. This highlights the importance of selecting a specific sample preparation order in this invention.

[0078] In summary, this invention provides a novel, simple, low-cost, and equipment-required method for preparing high-performance catalysts for oxygen evolution reaction in water electrolysis and for extracting lithium from recycled waste oxide cathode powder. By recycling retired nickel-cobalt-manganese ternary lithium (s-NCM) and lithium cobalt oxide (s-LCO) oxide cathode materials, electrodes are first prepared on a specific substrate. Then, surface modification is performed using plasma in a reducing atmosphere such as argon, successfully introducing high concentrations of oxygen vacancies and other defects into the material. Finally, through an electrochemical activation process in an alkaline electrolyte, the material undergoes a simultaneous transformation to a highly active phase such as Ni(Co,Mn)O2 / γ-Ni(Co,Mn)OOH heterojunction structures, as well as efficient dissolution of residual lithium ions. Compared with traditional battery material recycling, this invention eliminates the need for prolonged high-temperature pyrometallurgical reactions and the use of large amounts of acid and alkali reagents in hydrometallurgical processes. It is a low-cost, low-energy-consumption green recycling method that significantly reduces the environmental impact of waste batteries. This invention achieves the cascade utilization of resources by directly converting recycled materials into high-value-added products. In particular, the synergistic effect of plasma treatment and electrochemical activation is crucial: plasma pretreatment introduces defects, guiding the subsequent electrochemical reconstruction pathway and forming a heterojunction structure with excellent catalytic activity. This method exhibits broad applicability, not only suitable for oxide cathode materials of different compositions (such as ternary lithium and lithium cobalt oxide), but also effectively combined with industrial-grade self-supporting substrates such as nickel-iron foam. The localized metal ion environment provided by the substrate during reconstruction allows for secondary modification of the catalyst, thereby achieving a synergistic catalytic performance improvement of "1+1>2" in industrial applications. The resulting oxygen evolution reaction (OER) catalyst, compared to the untreated raw material, exhibits a qualitative leap in OER activity, reaching 10 mA·cm⁻¹. -2 With 100 mA·cm -2 The overpotential is significantly reduced at the current density. The catalyst prepared by this method is easy to operate and can be produced on a large scale, effectively improving the efficiency of hydrogen production through water electrolysis. Simultaneously, this invention achieves catalyst preparation and lithium extraction through an electrochemical activation process. The dissolved lithium ions, after being enriched in the electrolyte, can be further converted into high-value, high-quality lithium products such as lithium carbonate, providing a crucial raw material supplement for the new energy battery industry. This unique method not only greatly improves the economic benefits of waste battery recycling but also achieves a dual transformation from "waste" to "highly active catalyst" and "resource," possessing significant economic value and environmental significance.

[0079] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing a high-performance catalyst for oxygen evolution reaction in water electrolysis using plasma-treated waste lithium-ion battery cathode black powder, characterized in that, The method includes the following steps: (1) The waste positive electrode material of the waste lithium-ion battery is separated from the current collector and collected as waste black powder. The waste black powder is loaded onto a self-supporting substrate to prepare a pre-catalyst electrode. (2) The precatalyst electrode obtained in step (1) is modified by low-pressure non-thermal equilibrium plasma to obtain a plasma-modified precatalyst electrode. (3) The plasma-modified precatalyst electrode obtained in step (2) is electrochemically activated in an alkaline electrolyte system, so that the plasma-modified precatalyst electrode is reconstructed in situ into a high-performance working electrode for the oxygen evolution reaction catalyst of water electrolysis, and the residual lithium ions in the waste black powder are dissolved simultaneously.

2. The method for preparing a high-performance oxygen evolution reaction catalyst for water electrolysis using plasma-treated waste lithium-ion battery cathode black powder according to claim 1, characterized in that, In step (1), the process of separating the waste positive electrode material of the waste lithium-ion battery from the current collector and collecting it as waste black powder includes the following steps: completely discharging and disassembling the waste lithium-ion battery to obtain the positive electrode sheet; separating the active material and the current collector in the positive electrode sheet, and then drying and grinding the obtained active material to obtain retired positive electrode material powder, which is waste black powder.

3. The method for preparing a high-performance oxygen evolution reaction catalyst for water electrolysis using plasma-treated waste lithium-ion battery cathode black powder according to claim 1, characterized in that, In step (1), the waste black powder is one or more of ternary lithium, lithium manganese oxide, and lithium cobalt oxide; In step (1), the self-supporting substrate is one or more of foam metal, foam metal alloy, carbon paper, and carbon felt.

4. The method for preparing a high-performance oxygen evolution reaction catalyst for water electrolysis using plasma-treated waste lithium-ion battery cathode black powder according to claim 1, characterized in that, In step (2), during the low-pressure non-thermal equilibrium plasma modification process, non-thermal equilibrium plasma is used, and the non-thermal equilibrium plasma is selected from one or more of microwave plasma, radio frequency plasma, DC plasma, intermediate frequency plasma, dielectric barrier plasma, glow plasma or corona plasma.

5. The method for preparing a high-performance oxygen evolution reaction catalyst for water electrolysis using plasma-treated waste lithium-ion battery cathode black powder according to claim 1, characterized in that, In step (2), during the low-pressure non-thermal equilibrium plasma modification process, the total gas flow rate is 40~100 standard milliliters per minute, the plasma discharge environment pressure is 10~150 Pa, the discharge power is 100~500W, and the plasma treatment time is 1~10 min; the plasma discharge atmosphere is selected from one or more of argon, hydrogen, and nitrogen.

6. The method for preparing a high-performance oxygen evolution reaction catalyst for water electrolysis using plasma-treated waste lithium-ion battery cathode black powder according to claim 1, characterized in that, In step (3), the plasma-modified pre-catalyst electrode is activated as the anode under alkaline electrolyte conditions to be reconstructed into a high-performance working electrode for the oxygen evolution reaction catalyst of water electrolysis, and the residual lithium ions in the decommissioned cathode material are dissolved simultaneously. The alkaline electrolyte operating condition is the alkaline water electrolysis operating condition.

7. The method for preparing a high-performance oxygen evolution reaction catalyst for water electrolysis using plasma-treated waste lithium-ion battery cathode black powder according to claim 1, characterized in that, In step (3), the electrochemical activation is one of constant current treatment, constant voltage treatment, or cyclic voltammetry treatment; When using constant current processing, a current density of 5~1000 mA·cm is applied to the working electrode. -2 ; When using constant voltage processing, an external voltage of 1.3~1.8 V vs. RHE is applied to the working electrode; When using cyclic voltammetry, the cyclic range is 1.0 V to 1.6–2.0 V vs. RHE, and the scan rate is 1–200 mV·s. 1 .

8. The method for preparing a high-performance oxygen evolution reaction catalyst for water electrolysis using plasma-treated waste lithium-ion battery cathode black powder according to claim 1, characterized in that, In step (3), the lithium ions remaining in the plasma-modified pre-catalyst electrode are simultaneously dissolved to obtain an alkaline electrolyte rich in lithium ions. After step (3), perform the following step (4): The alkaline electrolyte rich in lithium ions from step (3) is collected, enriched by reflux, concentrated by evaporation, and then a precipitant is added to crystallize the lithium ions in the form of lithium salts, thereby achieving the extraction of lithium elements.

9. The method for preparing a high-performance oxygen evolution reaction catalyst for water electrolysis using plasma-treated waste lithium-ion battery cathode black powder according to claim 1, characterized in that, In step (1), the process of loading waste black powder onto a self-supporting substrate to prepare a pre-catalyst electrode includes the following steps: The waste black powder, conductive agent, and binder are mixed and dispersed evenly in a solvent to obtain a dispersion. The dispersion is then loaded onto a self-supporting substrate to obtain a pre-catalyst electrode.

10. A high-performance catalyst for the oxygen evolution reaction in water electrolysis, characterized in that, The high-performance water electrolysis oxygen evolution reaction catalyst is prepared by using plasma-treated waste lithium-ion battery cathode black powder as described in any one of claims 1 to 9.

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