Method for directly constructing high-entropy multi-metal catalyst based on waste battery leachate and application of high-entropy multi-metal catalyst

Abstract

The invention discloses a method for directly constructing a high-entropy multi-metal catalyst based on a waste battery leachate, which comprises the following steps: carrying out acid leaching treatment on a waste battery to obtain the waste battery leachate with mixed metal ions; adjusting the pH value of the reaction system, and meanwhile, introducing a proper amount of complexing agent or reducing agent or stabilizing agent to regulate and control the coordination state, deposition potential and reaction kinetic behavior of multiple metal ions; carrying out spray drying, electro-deposition, co-precipitation or sol-gel preparation process treatment, and carrying out induced reaction at proper temperature and reaction atmosphere to form a multi-principal-element metal oxide catalyst precursor; and calcining or reducing the obtained multi-principal element metal oxide catalyst precursor to prepare the high-entropy multi-metal catalyst material. According to the method, on the premise that complex metal separation and purification are not carried out, the multi-metal catalyst material is constructed by directly utilizing multiple metal ions in the waste battery leachate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalyst preparation and resource recycling, and particularly relates to a method for constructing a high-entropy multi-metal catalyst from waste battery leaching solution and application thereof. BACKGROUND

[0002] With the rapid development of new energy vehicles, energy storage systems and consumer electronics, large-scale production and use of lithium ion batteries has become an irreversible trend. Such waste batteries are rich in Co, Ni, Mn, Fe, Cu, Al, Li and other valuable metals, and their effective recovery and recycling have become the key to promoting resource circulation, reducing environmental risks and ensuring the safety of material supply chains.

[0003] The current mainstream treatment method is a hydrometallurgical leaching-separation process, that is, the metal is converted into ionic state by acid leaching, and then specific metals (such as Li, Co, Ni, etc.) are recovered by step-by-step purification. However, this process has the following problems: the "non-target metals" (such as Fe, Cu, Mn, Zn, etc.) are often treated as impurities, causing resource waste; the multi-step separation process is cumbersome, with high reagent consumption and energy consumption; and the metals in the remaining leaching solution are complex and mixed, making it difficult to further resource.

[0004] Some attempts have been made to use waste liquid for material construction, but most are limited to low-value-added uses such as adsorbents and electrode skeletons, and lack a structure-performance coupling design path starting from "waste liquid components", making it difficult to form high catalytic performance output.

[0005] High-entropy catalysts (HECs) are a research hotspot in the field of electrocatalysis. The basic concept is to construct a single phase or uniform distribution of a composite by using more than five metal ions with different chemical properties through a synergistic strategy to enhance the structural stability and catalytic activity of the material. The high-entropy structure can bring multiple catalytic active sites and enhance the ability to control the electronic structure, which can improve the performance of hydrogen evolution (HER), oxygen evolution (OER), and oxygen reduction (ORR) reactions.

[0006] However, the current preparation of high-entropy catalyst functional materials is based on high-purity metal salt systems (such as Ni(NO3)2, CoCl2, etc.), and requires precise proportioning and strict reaction control. Moreover, high-entropy catalyst functional materials are mostly single or binary metal systems, ignoring the synergistic effect of complex metal combinations in catalysis, which cannot fully utilize the synergistic effect of multiple metals, limiting the performance ceiling in key reactions such as hydrogen evolution (HER) and oxygen evolution (OER).

[0007] The coexisting valuable metals (such as Cu, Al, Zn, Fe, Co, Ni, Mn, etc.) in lithium ion battery leaching solution have resource value, and these metal elements are important components for constructing multi-metallic catalyst, especially suitable for high-entropy catalyst, high-efficiency hydrogen / oxygen evolution electrocatalyst and other functional material systems. How to realize controllable synthesis based on complex metal ion system and utilize component difference to regulate catalytic performance has become a key scientific problem for high-value utilization of resources. SUMMARY

[0008] In view of the deficiencies of the prior art, the purpose of the present application is a method for directly constructing high-entropy multi-metallic catalyst from waste battery leaching solution and its application, so as to realize the construction of multi-metallic catalyst material with high synergy, high structural stability and high catalytic activity by directly utilizing various metal ions in waste battery leaching solution without complex metal separation and purification.

[0009] In order to achieve the above purpose, the present application first provides a method for directly constructing high-entropy multi-metallic catalyst based on waste battery leaching solution, comprising the following steps:

[0010] S1, subjecting the positive electrode material of the scrapped waste battery to acid leaching treatment to obtain waste battery leaching solution with mixed metal ions, and removing insoluble impurities in the waste battery leaching solution by solid-liquid separation;

[0011] S2, adjusting the pH value of the reaction system according to the concentration ratio of each metal ion in the waste battery leaching solution and the target application requirement, and introducing appropriate complexing agent or reducing agent or stabilizer to regulate the coordination state, deposition potential and reaction kinetics behavior of the multi-metallic ions;

[0012] S3, treating by spray drying, electrodeposition, co-precipitation or sol-gel preparation process to induce reaction to form multi-principal metal oxide catalyst precursor under suitable temperature and reaction atmosphere;

[0013] S4, calcining or reducing the obtained multi-principal metal oxide catalyst precursor to prepare high-entropy multi-metallic catalyst material.

[0014] Preferably, the waste battery in step S1 is a ternary battery, a lithium iron phosphate battery, a lithium cobaltate battery, a lithium manganate battery or a combination thereof.

[0015] Preferably, the inlet liquid condition for spray drying in step S3 is a metal ion concentration of 0.1-1.0 mol / L.

[0016] Preferably, the electrodeposition process in step S3 is carried out at a constant current of 0.5 mA / cm 2 ~ 5 mA / cm 2Alternatively, the test can be performed under a constant voltage of 0.5V to 2.0V for 10 to 60 minutes.

[0017] Preferably, the precipitant used for co-precipitation in step S3 is an ammonium hydroxide solution.

[0018] Preferably, in step S4, the multi-principal metal oxide catalyst precursor is calcined in air or an inert atmosphere at a temperature of 300°C to 800°C.

[0019] This invention also provides a high-entropy multimetal catalyst, which is prepared by the method described above for directly constructing a high-entropy multimetal catalyst based on waste battery leachate; wherein the high-entropy multimetal catalyst has an amorphous pericrystalline structure, a medium / high-entropy oxide phase, or a multi-scale defect-rich structure.

[0020] The present invention also provides an application of the above-described high-entropy multimetal catalyst, which is used as an electrocatalyst for hydrogen evolution or oxygen evolution in electrocatalytic reactions.

[0021] The method for directly constructing a high-entropy multimetal catalyst based on waste battery leachate provided by this invention has the following technical advantages:

[0022] 1. By utilizing the differences and synergies of metal components, and by adjusting conditions such as pH, complexing agents, and reducing agents, the synergistic transformation behavior of multiple metal ions can be induced, breaking the traditional idea that only high-purity raw materials can produce superior catalysts.

[0023] 2. Based on the leachate of waste batteries, a construction path for high-entropy catalysts or multi-metal synergistic structural materials is established. High-performance catalytic products can be directly obtained through processes such as spray drying, electrodeposition, and pyrolysis. Complex metal ions in the waste liquid can be converted into functional catalytic materials without metal separation and purification.

[0024] 3. High-entropy multi-metal catalysts directly constructed from waste battery leachate are applied to electrocatalytic reactions, significantly improving the onset potential, reaction activity, and cycle stability of materials in HER, OER, and other applications, while reducing material preparation costs and promoting the transformation of waste battery resources towards higher added value. Attached Figure Description

[0025] Figure 1 A flowchart of a method for directly constructing a high-entropy polymetallic catalyst from waste battery leachate provided by the present invention;

[0026] Figure 2 The diagram shows the structural and component characterization results of Example 1;

[0027] Figure 3The graphs show the HER catalytic performance, electrochemical impedance spectroscopy, and response current stability test results of the samples from Example 1 and Comparative Examples 1-3.

[0028] Figure 4 This is a diagram showing the structural characterization results of Example 2;

[0029] Figure 5 The figures show the OER catalytic performance, electrochemical impedance spectroscopy, and response current stability test results of the samples corresponding to Examples 2, 4, and 5. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this application clearer, the present invention will be further described below with reference to the accompanying drawings and embodiments. The embodiments of the present invention include, but are not limited to, the following embodiments. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0031] In this embodiment, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0032] The terms "first" and "second," etc., used in the specification and claims of this embodiment are used to distinguish different objects, not to describe a specific order of objects. For example, "first target object" and "second target object," etc., are used to distinguish different target objects, not to describe a specific order of target objects.

[0033] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0034] In the description of the embodiments in this application, unless otherwise stated, "multiple" means two or more. For example, multiple processing units means two or more processing units; multiple systems means two or more systems.

[0035] Figure 1 A flowchart of a method for directly constructing a high-entropy multimetal catalyst from waste battery leachate provided by this invention is shown below. Figure 1 A method for directly constructing a high-entropy multimetal catalyst based on leachate from spent batteries includes the following steps:

[0036] S1. The positive electrode material of the scrapped battery is subjected to acid leaching treatment to obtain a waste battery leachate containing mixed metal ions. Insoluble impurities in the waste battery leachate are removed by solid-liquid separation.

[0037] In a preferred embodiment, the waste battery in step S1 is a ternary lithium battery, a lithium iron phosphate battery, a lithium cobalt oxide battery, a lithium manganese oxide battery, or a combination thereof.

[0038] In a preferred embodiment, the acid used for the acid leaching treatment can be a sulfuric acid, oxalic acid, or citric acid system.

[0039] In a specific implementation plan, cathode materials from discarded lithium-ion batteries, such as ternary NCM, lithium iron phosphate (LFP), lithium manganese oxide (LMO), and lithium cobalt oxide (LCO), are selected and subjected to acid leaching treatment, such as using a sulfuric acid, oxalic acid, or citric acid system, to convert them into materials containing Co. 2 + Ni 2 +、Mn 2+ Fe 2+ Cu 2+ Zn 2+ This solution contains a mixture of various metal ions, including Al3+. No further separation or purification is required; after removing insoluble impurities through solid-liquid separation, it can be used directly as a multi-metal source.

[0040] S2. Based on the concentration ratio of each metal ion in the leachate of waste batteries and the target application requirements, adjust the pH value of the reaction system, and introduce appropriate complexing agents, reducing agents or stabilizers to regulate the coordination state, deposition potential and reaction kinetics of the multi-metal ions.

[0041] In specific implementation schemes, the metal molar ratio and concentration of the leachate are adjusted according to the target catalytic reaction requirements, such as HER, OER, ORR, etc., and the pH value of the system is controlled to be 1-10. Complexing agents (such as ammonia, citric acid, EDTA, etc.), reducing agents (glucose) or stabilizers (such as PVP, PEG) can be added appropriately to regulate the nucleation process and the synergistic behavior of multiple metal ions.

[0042] S3. Through spray drying, electrodeposition, co-precipitation, or sol-gel preparation processes, a multi-principal metal oxide catalyst precursor is formed by inducing a reaction under suitable temperature and reaction atmosphere.

[0043] In a preferred embodiment, the liquid inlet conditions for spray drying in step S3 are a metal ion concentration of 0.1-1.0 mol / L.

[0044] In a preferred embodiment, the electrodeposition process in step S3 is carried out at a constant current of 0.5 mA / cm. 2 ~5mA / cm 2Alternatively, the test can be performed under a constant voltage of 0.5V to 2.0V for 10 to 60 minutes.

[0045] In a preferred embodiment, the precipitant used for co-precipitation in step S3 is an ammonium hydroxide solution.

[0046] S4. The obtained multi-principal metal oxide catalyst precursor is calcined or reduced to prepare high-entropy multi-metal catalyst materials.

[0047] In a preferred embodiment, in step S4, the multi-principal metal oxide catalyst precursor is calcined in air or an inert atmosphere at a temperature of 300°C to 800°C.

[0048] The construction process can achieve targeted regulation of the target electrocatalytic reaction performance by adjusting the metal ratio, additive type, and heat treatment conditions in the leachate.

[0049] This method bypasses a multi-step wet metal separation process and directly converts the leachate into a catalytic material.

[0050] A high-entropy multimetal catalyst is prepared by the method described above for directly constructing a high-entropy multimetal catalyst based on waste battery leachate; wherein the high-entropy multimetal catalyst has an amorphous pericrystalline structure, a medium / high-entropy oxide phase, or a multi-scale defect-rich structure.

[0051] An application of the aforementioned high-entropy multimetallic catalyst, wherein the high-entropy multimetallic catalyst is used as an electrocatalyst for hydrogen evolution (HER) or oxygen evolution (OER) in electrocatalytic reactions.

[0052] This method is applicable to the construction of electrocatalysts for hydrogen evolution and oxygen evolution, and can also be further applied to battery electrode materials or supercapacitor electrodes by adjusting the construction parameters.

[0053] This invention achieves targeted optimization of catalytic performance by in-situ regulating the synergistic conversion behavior of metal components, avoiding separation losses and resource waste in traditional wet recycling. The proposed method no longer relies on the individual purification of each metal element in the leachate, but instead takes "compositional diversity" and "synergistic catalytic activity of multiple principal elements" as its starting point, integrating resource attributes, structural construction, and performance characteristics to directly transform complex leachates into high-performance catalytic products.

[0054] The leachate originates from the acid leaching process of common lithium batteries such as waste lithium iron phosphate, ternary materials, and lithium manganese oxide. It contains various transition metals and heteroatom ions, including Co, Ni, Mn, Fe, Cu, Al, and Zn, naturally possessing the elemental basis for constructing high-entropy or multi-metal synergistic catalysts. By adjusting the pH value of the system and introducing complexing agents, reducing agents, or auxiliary agents, the reaction pathway can be controlled without separating individual components, achieving synergistic assembly and material conversion under strategies such as spray drying, electrodeposition, or pyrolysis.

[0055] The obtained catalytic materials exhibit unique heterogeneous structural features, such as medium-entropy / high-entropy oxides, multi-principal metal nanoparticles, and oxygen-rich vacancy defect structures, which significantly enhance their performance in electrocatalytic reactions. For example, in reactions such as hydrogen evolution and oxygen evolution, they possess advantages such as low overpotential, high specific activity, and long-term stability, far exceeding the performance of single metal catalysts.

[0056] Compared to existing recycling methods that focus on the separation of individual metals and the improvement of purity, the strategy of this invention emphasizes the driving relationship between component regulation and functional performance, stressing the overall design and synergistic transformation from the source waste liquid, significantly improving the added value and utilization depth of recycled resources. Its advantages are mainly reflected in: high resource integration: avoiding multi-step wet separation processes, saving energy and chemical reagents; strong performance controllability: adjusting the electronic structure and reaction sites of the catalyst through the metal component ratio and reaction environment; flexible construction strategy: adaptable to various molding methods such as spray-calcination, electrodeposition, and sol-gel; structural-functional integration: the product simultaneously possesses high specific surface area, abundant active sites, and a stable framework; and wide application fields: suitable for multiple scenarios such as water splitting, CO2 conversion, battery electrodes, and pollutant reduction.

[0057] Example 1

[0058] Example 1 provides a method for constructing a high-entropy oxide catalyst based on ternary lithium battery leachate, as detailed below:

[0059] (1) Raw material pretreatment: Waste ternary lithium battery cathode material (containing Ni, Co, and Mn) was leached in a 2 mol / L sulfuric acid system for 2 hours to obtain Ni-containing cathode material. 2 +、Co 2+ Mn 2+ Mixed metal solution. After solid-liquid separation, the pH is adjusted to 5.0 to remove iron and aluminum impurities.

[0060] (2) Metal ratio control: Add Fe to the solution 3+ A high-entropy metal component system was constructed by adjusting the molar ratio of Ni:Co:Mn:Fe in the aqueous solution to 0.57:0.18:0.13:0.18.

[0061] (3) Precursor preparation: The metal salt solution was sonicated for 30 min to ensure homogeneity. Then, the solution was atomized using an Owegels medical nebulizer to generate micro / nano-sized (approximately 2 μm) aerosol droplets. These metal ion-containing aerosol droplets were blown into the ammonium hydroxide solution with air, each droplet acting as a microreactor surrounded and complexed with OH-. After atomization, the ammonium hydroxide solution containing the aerosol droplets was filtered. The resulting precipitate was dried in a vacuum oven at 30°C to obtain the precursor powder.

[0062] (4) Calcination treatment: After drying the precipitate, it is calcined in air at 400°C for 4 hours to obtain high entropy oxide powder.

[0063] Its microstructure and surface state were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Figure 2 The diagram shows the structural and component characterization results of Example 1, where, Figure 2 In the middle (a), (b), and (c), respectively, are the X-ray diffraction (XRD) patterns of the high-entropy oxide in Example 1, which show the composition of the high-entropy oxide in Example 1; Figure 2 In the middle (d), (e), and (f), the corresponding scanning electron microscopy (SEM) images of the high-entropy oxide in Example 1 are respectively. Figure 2 (g) is the energy-dispersive X-ray spectrum (EDS spectrum) of the high-entropy oxide in Example 1, and (h) is the elemental mapping distribution diagram of the high-entropy oxide in Example 1. The elemental distribution and proportion in the high-entropy oxide are illustrated using EDS and mapping spectra. Figure 2 The structure and composition of the high-entropy oxide prepared in Example 1 can be obtained.

[0064] Among these studies, by investigating different oxidation temperatures, it was found that the high-entropy oxide nanoparticle catalyst composite material prepared in Example 1 at an oxidation temperature of 400℃ exhibited the highest catalytic activity and the lowest electrochemical resistance. Having discovered the excellent performance of the high-entropy oxide prepared at 400℃, Comparative Examples 1-3 were then set up to observe the catalytic performance of the high-entropy oxide with different compositions.

[0065] Comparative Example 1

[0066] Comparative Example 1 provides a method for preparing a high-entropy oxide nanoparticle catalyst, comprising the following steps:

[0067] (1) Raw material pretreatment: The provided waste ternary lithium battery cathode material (containing Ni, Co, and Mn) was leached in a 2 mol / L sulfuric acid system for 2 hours to obtain Ni-containing materials. 2 +、Co 2+ Mn2+ Mixed metal solution. After solid-liquid separation, the pH is adjusted to 5.0 to remove iron and aluminum impurities.

[0068] (2) Metal ratio control: Add Cu to the solution 2+ A high-entropy metal composition system was constructed by adjusting the molar ratio of Ni:Co:Mn:Cu in the aqueous solution to 0.57:0.18:0.13:0.18.

[0069] (3) Precursor preparation: The metal salt solution was sonicated for 30 min to ensure homogeneity. Then, the solution was atomized using an Owegels medical nebulizer to generate micro / nano-sized (approximately 2 μm) aerosol droplets. These metal ion-containing aerosol droplets were blown into the ammonium hydroxide solution with air, each droplet acting as a microreactor surrounded and complexed with OH-. After atomization, the ammonium hydroxide solution containing the aerosol droplets was filtered. The resulting precipitate was dried in a vacuum oven at 30°C to obtain the precursor powder.

[0070] (4) Calcination treatment: After drying the precipitate, it is calcined in air at 400°C for 4 hours to obtain high entropy oxide powder.

[0071] Comparative Example 2

[0072] Comparative Example 2 provides a method for preparing a high-entropy oxide nanoparticle catalyst, comprising the following steps:

[0073] (1) Raw material pretreatment: The provided waste ternary lithium battery cathode material (containing Ni, Co, and Mn) was leached in a 2 mol / L sulfuric acid system for 2 hours to obtain Ni-containing materials. 2 +、Co 2+ Mn 2+ Mixed metal solution. After solid-liquid separation, the pH is adjusted to 5.0 to remove iron and aluminum impurities.

[0074] (2) Metal ratio control: Add Fe to the solution 3+ Cu 2+ A high-entropy metal composition system was constructed by adjusting the molar ratio of Ni:Co:Mn:Cu:Fe in the solution to 0.57:0.18:0.13:0.18:0.18.

[0075] (3) Precursor preparation: The metal salt solution was sonicated for 30 min to ensure homogeneity. Then, the solution was atomized using an Owegels medical nebulizer to generate micro / nano-sized (approximately 2 μm) aerosol droplets. These metal ion-containing aerosol droplets were blown into the ammonium hydroxide solution with air, each droplet acting as a microreactor surrounded and complexed with OH-. After atomization, the ammonium hydroxide solution containing the aerosol droplets was filtered. The resulting precipitate was dried in a vacuum oven at 30°C to obtain the precursor powder.

[0076] (4) Calcination treatment: After drying the precipitate, it is calcined in air at 400°C for 4 hours to obtain high entropy oxide powder.

[0077] Comparative Example 3

[0078] Comparative Example 3 provides a method for preparing a medium-entropy oxide nanoparticle catalyst, comprising the following steps:

[0079] (1) Raw material pretreatment: The provided waste ternary lithium battery cathode material (containing Ni, Co, and Mn) was leached in a 2 mol / L sulfuric acid system for 2 hours to obtain Ni-containing materials. 2 +、Co 2+ Mn 2+ Mixed metal solution. After solid-liquid separation, the pH is adjusted to 5.0 to remove iron and aluminum impurities.

[0080] (2) Metal ratio regulation: The molar ratio of Ni:Co:Mn in the solution was adjusted to 0.57:0.18:0.13 to construct a high-entropy metal component system.

[0081] (3) Precursor preparation: The metal salt solution was sonicated for 30 min to ensure homogeneity. Then, the solution was atomized using an Owegels medical nebulizer to generate micro / nano-sized (approximately 2 μm) aerosol droplets. These metal ion-containing aerosol droplets were blown into the ammonium hydroxide solution with air, each droplet acting as a microreactor surrounded and complexed with OH-. After atomization, the ammonium hydroxide solution containing the aerosol droplets was filtered. The resulting precipitate was dried in a vacuum oven at 30°C to obtain the precursor powder.

[0082] (4) Calcination treatment: After drying the precipitate, it is calcined in air at 400°C for 4 hours to obtain high entropy oxide powder.

[0083] The samples from Example 1 and Comparative Examples 1-3 were prepared as electrodes. The catalytic activity and electrochemical resistance of the corresponding electrode materials obtained under different compositions were investigated and analyzed. The experimental methods are as follows:

[0084] An electrochemical workstation (CHI 760E) was used with a three-electrode system, employing the prepared electrode, carbon rod electrode, and Ag / AgCl electrode as the working electrode, counter electrode, and reference electrode, respectively, to test the electrochemical performance of the catalyst. All electrochemical experiments were conducted in an electrolytic cell containing 1.0 M KOH. The catalytic activity for water electrolysis was determined using linear sweep voltammetry (LSV, scan rate 2 mV s⁻¹). The HER kinetics of the catalyst were characterized using electrochemical impedance spectroscopy (EIS). Ohmic resistance (Rs) was obtained from the high-frequency region, and charge transfer resistance (Rct) was simulated from the radius of the arc on the Nyquist plot. Electrochemical impedance spectroscopy analysis was performed in the frequency range of 0.05 Hz to 0.1 MHz. The results are as follows: Figure 3 As shown, Figure 3 These are the HER catalytic performance, electrochemical impedance spectroscopy, and response current stability test results of the samples from Example 1 and Comparative Examples 1-3.

[0085] Among them, through Figure 3 As can be seen from (a), the sample prepared in Example 1 has the most positive LSV polarization curve onset potential and current density onset potential, the highest current density, and the strongest HER activity; through Figure 3 As can be seen from (b), the sample prepared in Example 1 exhibits the smallest semicircle in its electrochemical impedance spectroscopy charge transfer resistance (R_ct), lowest impedance, and optimal electron transport. Figure 3 As can be seen from (c), the sample prepared in Example 1 exhibits the best stability in terms of current density retention during long-term stability testing, with almost no attenuation within 50 hours.

[0086] Example 2

[0087] Example 2 provides a method for constructing a medium-entropy oxide catalyst based on lithium cobalt oxide battery leachate, as detailed below:

[0088] (1) Raw material pretreatment: The provided lithium cobalt oxide cathode material (containing Co) was leached in a 2 mol / L sulfuric acid system for 2 hours to obtain Co-containing... 2+ Mixed metal solution. After solid-liquid separation, the pH is adjusted to 5.0 to remove impurities.

[0089] (2) Metal ratio control: Add Ni to the solution 2+ Fe 3+ The precursor was used to adjust the final Ni:Co:Fe molar ratio to 0.57:0.18:0.18, thus constructing a medium-entropy metal composition system.

[0090] (3) Precursor preparation: The metal salt solution was sonicated for 30 min to ensure homogeneity. Then, the solution was atomized using an Owegels medical nebulizer to generate micro / nano-sized (approximately 2 μm) aerosol droplets. These metal ion-containing aerosol droplets were blown into the ammonium hydroxide solution with air, each droplet acting as a microreactor surrounded and complexed with OH-. After atomization, the ammonium hydroxide solution containing the aerosol droplets was filtered. The resulting precipitate was dried in a vacuum oven at 30°C to obtain the precursor powder.

[0091] (4) Calcination treatment: After drying the precipitate, it was calcined in air at 400°C for 4 hours to obtain FeCoNiO. x Medium entropy oxide powder.

[0092] Comparative Example 4

[0093] Comparative Example 4 provides a method for preparing an oxide nanoparticle catalyst, comprising the following steps:

[0094] (1) Raw material pretreatment: The provided lithium cobalt oxide cathode material (containing Co) was leached in a 2 mol / L sulfuric acid system for 2 hours to obtain Co-containing... 2+ Mixed metal solution. After solid-liquid separation, the pH is adjusted to 5.0 to remove impurities.

[0095] (2) Metal ratio control: Add Ni to the solution 2+ The solution was prepared, and the final Co:Ni molar ratio was adjusted to 0.57:0.18.

[0096] (3) Precursor preparation: The metal salt solution was sonicated for 30 min to ensure homogeneity. Then, the solution was atomized using an Owegels medical nebulizer to generate micro / nano-sized (approximately 2 μm) aerosol droplets. These metal ion-containing aerosol droplets were blown into the ammonium hydroxide solution with air, each droplet acting as a microreactor surrounded and complexed with OH-. After atomization, the ammonium hydroxide solution containing the aerosol droplets was filtered. The resulting precipitate was dried in a vacuum oven at 30°C to obtain the precursor powder.

[0097] (4) Calcination treatment: After drying the precipitate, it was calcined in air at 400°C for 4 hours to obtain CoNiO. x Oxide powder.

[0098] Comparative Example 5

[0099] Comparative Example 5 provides a method for preparing a metal oxide nanoparticle catalyst, comprising the following steps:

[0100] (1) Raw material pretreatment: The lithium cobalt oxide cathode material (containing Co) provided by the recycler was leached in a 2 mol / L sulfuric acid system for 2 hours to obtain Co-containing material. 2+ Mixed metal solution. After solid-liquid separation, the pH is adjusted to 5.0 to remove impurities.

[0101] (2) Precursor preparation: The metal salt solution was sonicated for 30 min to ensure homogeneity. Then, the solution was atomized using an Owegels medical nebulizer to generate micro / nano-sized (approximately 2 μm) aerosol droplets. These metal ion-containing aerosol droplets were blown into the ammonium hydroxide solution with air, each droplet acting as a microreactor surrounded and complexed with OH- ions. After atomization, the ammonium hydroxide solution containing the collected aerosol droplets was filtered. The resulting precipitate was dried in a vacuum oven at 30°C to obtain the precursor powder.

[0102] (3) Calcination treatment: After drying the precipitate, it was calcined in air at 400°C for 4 hours to obtain CoO. x Oxide powder.

[0103] The samples from Example 2 and Comparative Examples 4 and 5 were prepared as electrodes, and the catalytic activity and electrochemical resistance of the corresponding electrode materials were investigated and analyzed. The experimental methods are as follows:

[0104] An electrochemical workstation (CHI 760E) was used with a three-electrode system. The prepared electrode, carbon rod electrode, and Ag / AgCl electrode were used as the working electrode, counter electrode, and reference electrode, respectively, to test the electrochemical performance of the catalyst. All electrochemical experiments were conducted in an electrolytic cell containing 1.0 M KOH. The catalytic activity for water electrolysis was determined using linear sweep voltammetry (LSV, scan rate 2 mV s⁻¹). The OER kinetics of the catalyst were characterized using electrochemical impedance spectroscopy (EIS). Ohmic resistance (Rs) was obtained from the high-frequency region, and charge transfer resistance (Rct) was simulated from the radius of the arc on the Nyquist plot. Electrochemical impedance spectroscopy analysis was performed in the frequency range of 0.05 Hz to 0.1 MHz, and the results are as follows: Figure 4 As shown.

[0105] Figure 4 This is a diagram showing the structural characterization results of the sample in Example 2. Figure 5 The figures show the OER catalytic performance, electrochemical impedance spectroscopy, and response current stability test results of the samples corresponding to Examples 2, 4, and 5. Figure 5 (a) is the OER catalytic performance graph of the corresponding samples of Example 2 and Comparative Examples 4 and 5, which is used to show the catalytic activity of different samples in the oxygen evolution reaction; Figure 5(b) shows the electrochemical impedance spectroscopy of the samples corresponding to Example 2 and Comparative Examples 4 and 5, used to analyze the electrochemical kinetic processes such as charge transfer in the samples; Figure 5 (c) shows the response current stability test graphs for the samples corresponding to Example 2 and Comparative Examples 4 and 5, used to evaluate the current stability of the samples under long-term reaction. As can be seen from the graph, the FeCoNiO sample… X The corresponding OER catalytic activity is optimal, FeCoNiO X The smaller the semicircle diameter, the lower the charge transfer resistance. The current density of all three substances showed no significant decay over 10 hours. Among them, FeCoNiO... X It has the highest and most stable current density, combining high activity with long-term cycling stability.

[0106] Example 3

[0107] Example 3 provides a method for co-precipitating high-entropy oxide catalysts based on NCM waste batteries, as detailed below:

[0108] Using scrap NCM (LiNi1 / 3Co1 / 3Mn1 / 3O2) as raw material, leaching with 2 mol / L H2SO4 for 2 hours yielded Ni-containing... 2 +、Co 2+ Mn 2+ A metal solution. Cu is added. 2+ with Fe 2+ After supplementing the components, the metal molar ratio was adjusted to Ni:Co:Mn:Cu:Fe = 2:1:1:1:1, the pH was adjusted to 9.5, and NaOH and NH4HCO3 were added dropwise for co-precipitation to obtain a polymetallic hydroxide precursor. This precursor was calcined in air at 500℃ for 4 hours to convert into a high-entropy oxide. The catalyst showed an OER onset potential of 1.52V and an OER of 10mA / cm in an alkaline water electrolysis system. 2 The overpotential is 298mV, and it has been operating stably for over 60 hours.

[0109] Example 4

[0110] Example 4 provides a defect-rich multimetal catalyst constructed by spray drying of LFP leachate, as detailed below:

[0111] After thermal decarbonization of the retired lithium iron phosphate cathode, Fe was obtained by leaching using an oxalic acid + sulfuric acid system. 2+ Dominant leachate. Ni added. 2 +and Co 2+Subsequently, the metal ratio Fe:Ni:Co was adjusted to 2:1:1, and citric acid (Fe:Cit = 1:0.2) was added for complexation control. The resulting solution was atomized and sprayed into a 200℃ hot air system to form dry particles, which were then reduced in 5% H2 / Ar at 400℃ for 3 hours. The resulting amorphous / crystalline composite material was used for CO2 reduction reaction, exhibiting a CO selectivity of >88% at -0.8V vs RHE, and the structure remained stable without delamination after 10 hours of continuous reaction.

[0112] Example 5

[0113] Example 5 provides a method for electrodepositing a high-entropy multimetal film using an LCO / LMO hybrid electrode, as detailed below:

[0114] LCO and LMO were mixed in a 1:1 mass ratio and then leached with sulfuric acid to obtain a Co-containing product. 2+ Mn 2+ Li+ metal solution. Add Zn. 2+ with Ni 2 The metal ratio was adjusted to Co:Mn:Zn:Ni = 1:1:1:1, and the pH was adjusted to 3.5. Using carbon cloth as the cathode, electrodeposition was performed at a constant potential of -1.2V for 30 minutes to obtain a well-adhered multimetallic hydroxide deposition layer. This deposition layer was calcined in air at 450℃ for 2 hours to form a high-entropy catalyst layer. When used in the HER reaction, the current is -10mA / cm. 2 The overpotential is only 87mV, and the cycle stability exceeds 1000 cycles.

[0115] Example 6

[0116] Example 6 provides a method for constructing nitrogen-doped high-entropy oxynitrides using a sol-gel method with mixed leachate from waste batteries, as detailed below:

[0117] Ni obtained by comprehensive wet leaching 2 +、Co 2+ Mn 2+ Fe 3+ An Al3+ mixture (derived from various waste LFP / NCM / LCO solutions) was mixed with citric acid and urea. The molar ratio of all metals, citric acid, and urea was 1:1.5:3 (metal:Cit:Urea). This formed a transparent sol, which was then evaporated at 80°C with stirring to obtain a gel. The dried gel was pyrolyzed at 600°C for 2 hours under a nitrogen atmosphere to form a nitrogen-containing high-entropy oxynitride. This material exhibited excellent OER / ORR bifunctional activity in a neutral electrolyte, with a voltage difference ΔE = 0.78V, making it suitable for metal-air battery cathodes.

[0118] Example 7

[0119] Example 7 provides a high-entropy precursor prepared from a mixture of lithium iron phosphate (LFP) and NCM waste, as detailed below:

[0120] LFP and NCM waste were mixed in a 2:1 ratio and leached using a combined oxalic acid and citric acid system to obtain a multi-metallic mixed solution containing Fe, Ni, Co, Mn, and Al. Based on the target material design, the Fe:Ni:Co:Mn:Al ratio was adjusted to 1:1:1:1:0.5, and free Al³⁺ and phosphate ions were removed by pH adjustment. A spray drying device with atomized particle size controlled at 5–10 μm was used for rapid drying into spherical precursor particles under 180°C air intake conditions. Calcination at 450–650°C under a nitrogen atmosphere yielded a multi-metallic oxide with a spinel-like structure. Under alkaline conditions, it was used in the oxygen evolution reaction of water electrolysis; the initial potential was below 1.52V, and no structural delamination or phase transition occurred after 50 hours of cycling.

[0121] Example 8

[0122] Example 8 provides a high-entropy catalyst prepared by introducing rare earth elements into a waste LCO electrode solution, as detailed below:

[0123] High-concentration Co was obtained by leaching waste lithium cobalt oxide (LCO) electrodes using an HCl + H₂O₂ system. 2+ Solution, with Ce added simultaneously 3+ La 3+ with Fe 2+ The precursor forms a multi-metallic system of Co:Ce:La:Fe = 1:1:1:1. After blending the solution with a SiO2 nanosphere template, the pH is adjusted to 10 with ammonia to induce the formation of a metal hydroxide coating layer. Following drying, the mixture is pyrolyzed at 500°C in air, and the SiO2 is removed by HF etching to obtain high-entropy oxide nanoparticles with a mesoporous structure. These nanoparticles exhibit high degradation rates and stability in the photocatalytic degradation of organic pollutants (such as methyl orange), demonstrating the potential of multi-metal synergy for environmental catalysis.

[0124] In summary, this invention provides a method for directly constructing high-entropy multimetal catalysts from waste battery leachate and its application. Using waste battery leachate as raw material, and combining metal diversity with reaction condition control, a high-entropy multimetal catalyst with excellent functional performance is constructed. This not only realizes the high-value utilization of battery waste liquid resources, but also provides a new resource-structure-performance integration approach for the design of high-performance electrocatalytic materials.

[0125] The above description is only a specific embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A method for constructing high-entropy multi-metallic catalysts directly based on spent battery leachate, characterized in that, The method comprises the following steps: S1, the positive electrode material of the scrapped waste battery is subjected to acid leaching treatment to obtain a waste battery leaching solution with mixed metal ions, and insoluble impurities in the waste battery leaching solution are removed by solid-liquid separation; S2, according to the concentration ratio of each metal ion in the waste battery leaching solution and the target application requirement, the pH value of the reaction system is adjusted, and an appropriate amount of complexing agent or reducing agent or stabilizer is introduced to regulate the coordination state, deposition potential and reaction kinetics behavior of the multi-metal ions; S3, by spray drying, electrodeposition, co-precipitation or sol-gel preparation process treatment, the reaction is induced to form a multi-principal element metal oxide catalyst precursor under suitable temperature and reaction atmosphere; S4, the obtained multi-principal element metal oxide catalyst precursor is calcined or reduced to prepare a high-entropy multi-metal catalyst material.

2. The method for constructing high-entropy multi-metal catalysts directly based on waste battery leaching solution according to claim 1, characterized in that, The waste battery in the step S1 is a ternary battery, a lithium iron phosphate battery, a lithium cobaltate battery, a lithium manganate battery or a combination thereof.

3. The method for constructing high-entropy multi-metal catalysts directly based on waste battery leaching solution according to claim 1, characterized in that, The liquid inlet condition of the spray drying in the step S3 is that the metal ion concentration is 0.1 mol / L-1.0 mol / L.

4. The method for constructing high-entropy multi-metal catalysts directly based on waste battery leaching solution according to claim 1, characterized in that, The electrodeposition process in step S3 is carried out under a constant current of 0.5 mA / cm 2 ~ 5 mA / cm 2 or a constant voltage of 0.5 V ~ 2.0 V, for 10 min ~ 60 min.

5. The method for constructing high-entropy multi-metal catalysts directly based on waste battery leaching solution according to claim 1, characterized in that, The precipitant used in the co-precipitation in the step S3 is ammonium hydroxide solution.

6. The method for constructing high-entropy multi-metal catalysts directly based on waste battery leaching solution according to claim 1, characterized in that, The multi-principal element metal oxide catalyst precursor in the step S4 is calcined in air or inert atmosphere, and the calcination temperature is 300-800 DEG C.

7. A high-entropy multi-metallic catalyst characterized in that, A high-entropy multi-metal catalyst is prepared by the method according to any one of the above claims 1-6. The high-entropy multi-metal catalyst has an amorphous crystalline structure, a medium / high-entropy oxide phase, or a multi-scale defect-rich structure.

8. Use of a high-entropy multi-metal catalyst according to any one of claims 1 to 7, characterized in that, The high-entropy multi-metal catalyst is used for hydrogen evolution or oxygen evolution electrocatalyst in an electrocatalytic reaction.

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