A method for preparing a graphite-supported built-in electric field M@alphaM@betaM high-entropy alloy catalyst by using waste ternary lithium batteries
By preparing a graphite-supported high-entropy alloy catalyst with an internal electric field M@αM@βαM, the side reaction problem of lithium-oxygen battery cathode catalyst was solved, the catalytic activity and stability were improved, and the dual-functional catalytic requirements of lithium-oxygen batteries were met.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- QINGDAO UNIV OF SCI & TECH
- Filing Date
- 2025-11-26
- Publication Date
- 2026-07-03
AI Technical Summary
Existing lithium-oxygen battery cathode catalysts exhibit side reactions during the reaction process, generating byproducts that are difficult to decompose, leading to excessively high overpotentials and unstable cycle performance. Traditional catalyst preparation methods result in particle agglomeration and a reduction in active sites, affecting catalytic performance.
A graphite-supported high-entropy alloy catalyst with a built-in electric field M@αM@βαM was prepared using spent ternary lithium batteries. The built-in electric field and multilayer high-entropy alloy structure were constructed through Joule heating, thereby regulating the electronic state and active sites of the catalyst, forming an interaction between the built-in electric field and 4f-3d orbitals, and optimizing the catalytic reaction.
It improves the catalytic activity and stability of lithium-oxygen batteries, extends catalyst life, reduces reaction activation energy, enhances the efficiency of oxygen reduction and oxygen evolution reactions, and meets the requirements of lithium-oxygen batteries for bifunctional catalysts.
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Figure CN121565875B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of recycling technology of waste ternary lithium batteries, specifically relating to a method for preparing graphite-supported high-entropy alloy catalysts with built-in electric fields M@αM@βαM using waste ternary lithium batteries. Background Technology
[0002] The global lithium-ion battery market is experiencing rapid expansion, with its market size in 2025 significantly exceeding previous expectations. Demand from new energy vehicles contributed over 70% of this growth. This growth has also led to a surge in retired batteries, with the first large-scale retirement wave expected globally in 2025. It is estimated that China alone will see nearly 800,000 tons of retired power batteries, and global waste is projected to further increase by 2030. Against this backdrop, the recycling of spent ternary lithium batteries has become a core support for building a closed-loop circular economy of "production-use-recycling-regeneration." This not only recovers the value of strategic resources such as Li, Ni, Co, Mn, and graphite, but also mitigates the environmental risks of heavy metal leakage and electrolyte pollution. Current mainstream recycling technologies are still based on pyrometallurgy and hydrometallurgy, while biometallurgy and solvent metallurgy technologies continue to develop. Leading companies have achieved breakthroughs in NiCoMn comprehensive recovery rates of 99.6% and lithium recovery rates of 96.5%. Although waste battery recycling technology has been relatively well-developed in some aspects, it still faces problems such as high technical costs, low yield, poor environmental friendliness, and safety hazards, and there is still room for improvement in many areas.
[0003] Compared to lithium-ion batteries, lithium-oxygen batteries have significant advantages. Firstly, they break through energy density bottlenecks. The theoretical energy density of lithium-ion batteries is limited by the lithium storage capacity of the positive and negative electrode materials. Commercially available lithium-ion batteries based on graphite negative electrodes have reached their energy density limit (350Wh / kg), making it difficult to meet the demands for long-range driving. In contrast, lithium-oxygen batteries have a theoretical energy density as high as 3500Wh / kg, far exceeding traditional lithium-ion batteries, providing crucial technological support for long-range devices and meeting the ever-evolving energy density requirements of power batteries. Secondly, their cost competitiveness is significantly improved. Lithium-ion battery production relies on primary resources, and cost is highly tied to resource supply; lithium-oxygen batteries have a better cost advantage. Thirdly, their safety performance is more guaranteed. Lithium-ion batteries are prone to thermal runaway under extreme conditions such as overcharging, discharging, and high temperatures, leading to risks such as overheating, explosion, or fire. Lithium-oxygen batteries, on the other hand, use oxygen as the positive electrode active material. This gaseous positive electrode design not only improves battery stability but also reduces the safety hazards associated with liquid electrolytes.
[0004] The performance of lithium-oxygen batteries depends on the reversible formation and decomposition of solid-phase Li₂O₂. The positive electrode reaction of a lithium-oxygen battery involves three phases: solid, liquid, and gas. The discharge process is an oxygen reduction process (ORR), corresponding to 2Li₂O₂. + +O2+2e- →Li₂O₂, lithium is oxidized to Li₂. + It then dissolves in the organic electrolyte and is transferred to the positive electrode. Simultaneously, electrons are transferred to the positive electrode side through the external circuit. The active substance oxygen is reduced on the catalyst surface of the positive electrode after passing through the pores of the air electrode, and forms O after gaining electrons. 2- and O2 2- After reacting with lithium ions in the organic electrolyte, it eventually forms Li2O2 deposits that adhere to the catalyst and electrode surfaces; the charging process is an oxygen evolution process (OER), corresponding to Li2O2 → 2Li + +O2+2e - The generated discharge product Li2O2 decomposes during charging, eventually breaking down into lithium ions and oxygen. The oxygen is released back into the environment, while the lithium ions undergo an electron-gaining reduction reaction on the negative electrode surface after entering the electrolyte, generating elemental lithium. However, side reactions occur during the reaction process, generating difficult-to-decompose byproducts such as Li2CO3, HCOOLi, and CH3COOLi, which passivate the positive electrode, sluggish the ORR and OER reaction kinetics, and cause excessively high overpotentials and unstable cycle performance.
[0005] To address the aforementioned issues, developing highly catalytic, stable, and low-cost cathode catalysts is crucial. Currently, researchers have developed many excellent cathode catalysts for lithium-oxygen batteries, such as carbon-based materials, noble metals and their compounds, single-atom catalysts, transition metals and their compounds. Traditional catalysts tend to be prepared through solvothermal or prolonged high-temperature calcination, which often leads to catalyst particle agglomeration, reducing the number of active sites and decreasing dispersion, severely impacting catalytic performance. Furthermore, during long-term cycling, the catalyst is continuously eroded, and the active sites are gradually passivated, prematurely losing catalytic activity. Summary of the Invention
[0006] This invention discloses a method for preparing graphite-supported high-entropy alloy catalysts with built-in electric fields M@αM@βαM using waste ternary lithium batteries, with the aim of solving the problems described in the background art.
[0007] To achieve the above objectives, the technical solution of the present invention is as follows:
[0008] A method for preparing graphite-supported high-entropy alloy catalysts with built-in electric fields M@αM@βαM using spent ternary lithium batteries includes the following steps:
[0009] Step 1: Discharge and disassemble the waste ternary lithium battery to recover graphite carbon powder A from the negative electrode copper sheet and NiCoMn ion solution B from the positive electrode.
[0010] Step 2: Mix the recovered NiCoMn solution B and graphite carbon powder A together in anhydrous ethanol, stir to adsorb evenly, evaporate to dryness, grind and dry to obtain precursor powder I;
[0011] Step 3: Precursor powder I is subjected to Joule thermal shock in a Joule heating apparatus to obtain graphite-loaded M (Ni) 1 / 3Co 1 / 3 Mn 1 / 3 Low-entropy alloys;
[0012] Step 4: Mix the graphite-supported M low-entropy alloy with La metal salt and NiCoMn solution B in anhydrous ethanol, stir to adsorb evenly, evaporate to dryness and grind to obtain precursor powder II.
[0013] Step 5: Precursor powder II is subjected to secondary Joule heating, and a medium-entropy alloy layer αM(La) is successfully coated onto the surface of the low-entropy alloy M through thermal shock. 1 / 4 Ni 1 / 4 Co 1 / 4 Mn 1 / 4 ), to obtain a graphite-supported M@αM medium-entropy alloy;
[0014] Step 6: Mix the graphite-supported M@αM medium-entropy alloy with La metal salt, Ce metal salt, and NiCoMn solution B in anhydrous ethanol to prepare precursor powder III;
[0015] Step 7: The precursor powder III is fed into a Joule heating device for three Joule heatings. Through thermal shock, a high-entropy alloy layer βαM (Ce) is successfully coated onto the surface of the M@αM medium-entropy alloy. 1 / 5 La 1 / 5 Ni 1 / 5 Co 1 / 5 Mn 1 / 5 ), and graphite-supported M@αM@βαM high-entropy alloy catalyst was prepared.
[0016] Preferably, step 1 includes:
[0017] (1) After the waste ternary lithium battery is fully discharged, it is disassembled, the negative electrode is peeled off and taken out, cut into small pieces of 5cm*1cm, wrapped with carbon paper and placed in a Joule heating device for thermal shock. After holding at about 800℃ for 5-10s to carbonize the binder, the graphite is scraped off and ground, and then acid-leached with 5M-10M nitric acid, washed with water, centrifuged, and vacuum dried to obtain the recycled graphite carbon powder A.
[0018] (2) After stripping the NiCoMn-containing cathode, cut it into 5cm*1cm pieces and place it in a dimethyl ethylene glycol (DME) solution for sonication for 15-20h, keeping the temperature below 30℃ during the process; centrifuge and dry the obtained leachate to obtain powder containing LiNiCoMn; place the powder in a 5M-10M potassium carbonate solution and stir in an oil bath at 50-60℃ for 2-5h, then centrifuge and wash with water to remove lithium impurities to obtain NiCoMn carbonate precipitate; add the precipitate to a 5M acetic acid solution, stir thoroughly to dissolve, centrifuge and take the supernatant to obtain solution B containing NiCoMn ions.
[0019] Preferably, step 2 includes:
[0020] Take 500 mg of graphite carbon powder A and an appropriate amount of solution B and mix them in 50 ml of anhydrous ethanol. The volume of solution B should be controlled at about 10 mL. Stir magnetically at 80 °C for 8 h and evaporate to dryness. After vacuum drying, take it out and grind it to obtain precursor powder I.
[0021] Preferably, step 3 includes:
[0022] Precursor powder I was placed in a Joule heating apparatus and held at approximately 1500°C for 10-12 seconds, then rapidly cooled to room temperature within 5 seconds to obtain graphite-supported M(Ni). 1 / 3 Co 1 / 3 Mn 1 / 3 Low-entropy alloys.
[0023] Preferably, step 4 includes: taking 300mg of graphite-supported M low-entropy alloy powder and dispersing it fully in 40ml of anhydrous ethanol; adding solution B and La metal salt in a molar ratio of 1:1; controlling the total volume of solution B and La metal salt to about 6ml; evaporating the solution by magnetic stirring at 80℃ for 8h; vacuum drying; and then grinding the solution to obtain precursor powder II.
[0024] Preferably, step 5 includes: placing the precursor powder II in a Joule heating device and holding it at approximately 1500°C for 10-12 seconds, then rapidly cooling it to room temperature within 5 seconds, and coating the surface of the low-entropy alloy M with a medium-entropy alloy layer αM(La). 1 / 4 Ni 1 / 4 Co 1 / 4 Mn 1 / 4 ), thus obtaining a graphite-loaded M@αM medium-entropy alloy.
[0025] Preferably, step 6 includes: taking 100mg of graphite-supported M@αM medium-entropy alloy powder and adding it to 40ml of anhydrous ethanol for thorough dispersion; adding solution B, La metal salt, and Ce metal salt in a molar ratio of 1:1:1; controlling the total volume of solution B, La metal salt, and Ce metal salt to about 2ml; evaporating the solution by magnetic stirring at 80℃ for 8h; vacuum drying; and then grinding the solution to obtain precursor powder III.
[0026] Preferably, step 7 includes: placing the precursor powder III in a Joule heating device, holding it at approximately 1500°C for 10-12 seconds, then rapidly cooling it to room temperature within 5 seconds, and coating the M@αM surface with a high-entropy alloy layer βαM (Ce 1 / 5 La 1 / 5 Ni 1 / 5 Co 1 / 5 Mn 1 / 5 ), thus obtaining a graphite-supported M@αM@βαM high-entropy alloy catalyst.
[0027] The beneficial effects of the method for preparing graphite-supported high-entropy alloy catalysts with built-in electric fields M@αM@βαM using spent ternary lithium batteries are as follows:
[0028] This invention has the following advantages:
[0029] (1) By using this method to process waste ternary lithium batteries, valuable metals Ni, Co, Mn and graphite can be recycled and reused. The recycling rate is high, the purity is high, the method is easy and environmentally friendly, which can greatly promote the recycling of waste resources.
[0030] (2) Advantages of high-entropy ordered alloys: High-entropy alloys formed by five or more metal elements have abundant and tunable catalytic active sites. Multi-element synergy can construct active centers, and the differences in electronic structure of different elements will form "electronic heterogeneous interfaces", generating a variety of active sites that can adapt to the adsorption requirements of reaction intermediates. By adjusting the element ratio or ordered structure, the electronic state (such as d-band center) and geometric environment (such as interatomic spacing) of active sites can be precisely controlled, thereby optimizing the catalytic reaction energy barrier and improving activity and selectivity. The high-entropy effect enhances corrosion resistance and can reduce the corrosion of active sites by electrolyte; at the same time, high-entropy alloys have high thermodynamic stability and can inhibit the dissolution or phase transformation of catalysts in the reaction. The ordered structure can make active element atoms uniformly distributed on specific crystal planes, avoiding the problem of active sites being "shielded by inert elements" in disordered alloys, further improving atomic utilization efficiency. Compared with disordered high-entropy alloys, the ordered structure has regular atomic arrangement and strong bonding force, which can avoid the segregation and agglomeration of active elements due to high temperature or electrolyte erosion during the reaction, thus extending the catalyst life. At the same time, a large number of lattice distortions will form on the alloy surface, thereby generating abundant active sites. These sites serve as key sites for the oxygen reduction (ORR) / oxygen evolution (OER) reaction, which helps the adsorption and desorption of oxygen molecules and intermediate products, effectively improving the ORR / OER reaction efficiency.
[0031] (3) Advantages of built-in electric fields: Built-in electric fields are not externally applied electric fields, but rather potential differences spontaneously formed at the interface or inside the material through its own structure. Built-in electric fields can fundamentally optimize the charge transfer process, thereby significantly improving the efficiency of catalytic reactions. By adjusting the electronic state density on the catalyst surface, built-in electric fields provide a "driving force" for the transfer of charge between the catalyst and reactants, reducing the transfer energy barrier; by changing the adsorption energy and reaction path of reaction intermediates through potential differences, they can "guide" the preferential adsorption of specific reactant molecules and stabilize the intermediates required for the target reaction, inhibiting the formation of side reaction intermediates, thereby improving the yield of the target product; through the electric field polarization effect, they directly act on the reaction system, weakening the chemical bonds in the reactant molecules, reducing the reaction activation energy, and improving catalytic kinetics. In M@αM@βαM, based on the differences in electronegativity among elements (Ni (1.91), Co (1.88), Mn (1.55), La (1.10), Ce (1.12), the highly electronegative inner-layer Ni / Co / Mn attracts electrons from the middle-layer La, resulting in a negatively charged inner-layer interface and a positively charged middle-layer interface, creating an electric field from the middle layer to the inner layer. The outer layer contains Ce, which has a slightly higher electronegativity than La. The highly electronegative Ce and Ni / Co / Mn in the outer layer attract electrons from the middle-layer La, resulting in a negatively charged outer-layer interface. The middle layer is negatively charged, while the middle layer is positively charged, generating an electric field from the middle layer to the outer layer. The electric fields at both interfaces are centered on the middle layer as the positive charge center, pointing towards the inner and outer layers respectively, forming a bidirectional electric field distribution of "middle layer outward radiation". This electric field guides electrons to accumulate from the middle layer with the lowest electronegativity and transfer to the inner and outer layers with higher electronegativity, which can optimize the charge distribution on the catalyst surface. It is suitable for catalytic reactions that require bidirectional charge regulation (such as redox coupling reactions), which meets the requirements of lithium-oxygen battery catalysts for OER / ORR bifunctional catalysis.
[0032] (4) Advantages of 4f-3d orbital interaction: In alloy catalysts, the interaction between rare earth 4f orbitals and transition metal 3d orbitals is mainly achieved through electronic state regulation and active site synergy, which precisely optimizes the adsorption energy of reaction intermediates and reduces the activation energy of the reaction, thereby improving the activity, selectivity and stability of the catalyst. The electrons (or empty orbitals) of rare earth 4f orbitals will transfer some charge to the transition metal 3d orbitals, changing the filling degree of the 3d orbitals, which can make the electronic state density of the 3d orbitals closer to the "optimal energy level" of the catalytic reaction, like precisely "charging" the "active center", enhancing the adsorption and activation ability of reaction molecules. The strong locality of 4f orbitals can anchor the position of transition metal atoms and inhibit their aggregation in the reaction; at the same time, the ductility of 3d orbitals can maintain the conductivity of the alloy structure. The two work together to prevent the catalyst from being deactivated due to structural collapse or electron loss. In the OER process, the excessive adsorption of reaction intermediates can be weakened, avoiding the "poisoning" of active sites, while maintaining the necessary adsorption strength to activate reactants and reduce the reaction activation energy; in the ORR process, the selectivity of the ORR reaction can be enhanced and the formation of by-products can be reduced.
[0033] (5) This method is universal. By changing the types of α and β rare earth metal salts (α, β = La salt, Ce salt, Pr salt, Nd salt, etc.), a series of graphite-supported M@αM@βαM catalysts can be obtained.
[0034] (6) This method has a wide range of raw material sources, avoids the use of precious metals, has low rare earth prices, simple synthesis process, good repeatability, strong applicability, and is suitable for industrial-scale production. Attached Figure Description
[0035] Figure 1 This is a scanning electron microscope image of the graphite-supported M@αM@βαM catalyst;
[0036] Figure 2 The X-ray diffraction curves of graphite-supported M@αM@βαM catalyst powder are shown.
[0037] Figure 3 The full charge-discharge performance curves of lithium-oxygen batteries with graphite-supported M@αM@βαM catalysts are shown.
[0038] Figure 4 This is a graph showing the cycle performance of a lithium-oxygen battery with a graphite-supported M@αM@βαM catalyst. Detailed Implementation
[0039] The following description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
[0040] The following embodiments can be understood as illustrating a part of the structure or method of the present invention individually, or as combining the embodiments to explain the broader structure or method of the present invention.
[0041] Example 1:
[0042] A method for preparing graphite-supported high-entropy alloy catalysts with built-in electric fields M@αM@βαM using spent ternary lithium batteries includes the following steps:
[0043] Step 1: Discharge and disassemble the waste ternary lithium battery to recover graphite carbon powder A from the negative electrode copper sheet and NiCoMn ion solution B from the positive electrode.
[0044] Step 2: Mix the recovered NiCoMn solution B and graphite carbon powder A together in anhydrous ethanol, stir to adsorb evenly, evaporate to dryness, grind and dry to obtain precursor powder I;
[0045] Step 3: Precursor powder I is subjected to Joule thermal shock in a Joule heating apparatus to obtain graphite-loaded M (Ni) 1 / 3Co 1 / 3 Mn 1 / 3 Low-entropy alloys;
[0046] Step 4: Mix the graphite-supported M low-entropy alloy with La metal salt and NiCoMn solution B in anhydrous ethanol, stir to adsorb evenly, evaporate to dryness and grind to obtain precursor powder II.
[0047] Step 5: Precursor powder II is subjected to secondary Joule heating, and a medium-entropy alloy layer αM(La) is successfully coated onto the surface of the low-entropy alloy M through thermal shock. 1 / 4 Ni 1 / 4 Co 1 / 4 Mn 1 / 4 ), to obtain a graphite-supported M@αM medium-entropy alloy;
[0048] Step 6: Mix the graphite-supported M@αM medium-entropy alloy with La metal salt, Ce metal salt, and NiCoMn solution B in anhydrous ethanol until homogeneous, stir to adsorb evenly, evaporate to dryness, grind and dry to obtain precursor powder III.
[0049] Step 7: The precursor powder III is fed into a Joule heating device for three Joule heatings. Through thermal shock, a high-entropy alloy layer βαM (Ce) is successfully coated onto the surface of the M@αM medium-entropy alloy. 1 / 5 La 1 / 5 Ni 1 / 5 Co 1 / 5 Mn 1 / 5 ), and graphite-supported M@αM@βαM high-entropy alloy catalyst was prepared.
[0050] Example 2:
[0051] Based on Example 1, step 1 includes:
[0052] (1) After the waste ternary lithium battery is fully discharged, it is disassembled, the negative electrode is peeled off and taken out, cut into small pieces of 5cm*1cm, wrapped with carbon paper and placed in a Joule heating device for thermal shock. After holding at about 800℃ for 5-10s to carbonize the binder, the graphite is scraped off and ground, and then acid-leached with 5M-10M nitric acid, washed with water, centrifuged, and vacuum dried to obtain the recycled graphite carbon powder A.
[0053] (2) After stripping the NiCoMn-containing cathode, cut it into 5cm*1cm pieces and place it in a dimethyl ethylene glycol (DME) solution for sonication for 15-20h, keeping the temperature below 30℃ during the process; centrifuge and dry the obtained leachate to obtain powder containing LiNiCoMn; place the powder in a 5M-10M potassium carbonate solution and stir in an oil bath at 50-60℃ for 2-5h, then centrifuge and wash with water to remove lithium impurities to obtain NiCoMn carbonate precipitate; add the precipitate to a 5M acetic acid solution, stir thoroughly to dissolve, centrifuge and take the supernatant to obtain solution B containing NiCoMn ions.
[0054] Example 3:
[0055] Based on embodiments 1 and 2, step 2 includes:
[0056] Take 500 mg of graphite carbon powder A and an appropriate amount of solution B and mix them in 50 ml of anhydrous ethanol. The volume of solution B should be controlled at about 10 mL. Stir magnetically at 80 °C for 8 h and evaporate to dryness. After vacuum drying, take it out and grind it to obtain precursor powder I.
[0057] Example 4:
[0058] Based on embodiments 1, 2, and 3, step 3 includes:
[0059] Precursor powder I was placed in a Joule heating apparatus and held at approximately 1500°C for 10-12 seconds, then rapidly cooled to room temperature within 5 seconds to obtain graphite-supported M(Ni). 1 / 3 Co 1 / 3 Mn 1 / 3 Low-entropy alloys.
[0060] Example 5:
[0061] Based on Examples 1-4, step 4 includes: taking 300mg of graphite-supported M low-entropy alloy powder and adding it to 40ml of anhydrous ethanol for thorough dispersion; adding solution B and La metal salt in a molar ratio of 1:1; controlling the total volume of solution B and La metal salt to about 6ml; evaporating the solution by magnetic stirring at 80℃ for 8h; vacuum drying; and then grinding the solution to obtain precursor powder II.
[0062] Example 6:
[0063] Based on Examples 1-5, step 5 includes: placing the precursor powder II in a Joule heating device and holding it at approximately 1500°C for 10-12 seconds, then rapidly cooling it to room temperature within 5 seconds, and coating the surface of the low-entropy alloy M with a medium-entropy alloy layer αM(La). 1 / 4 Ni 1 / 4 Co 1 / 4 Mn 1 / 4 ), thus obtaining a graphite-loaded M@αM medium-entropy alloy.
[0064] Example 7:
[0065] Based on Examples 1-6, step 6 includes: taking 100mg of graphite-supported M@αM medium-entropy alloy powder and adding it to 40ml of anhydrous ethanol for thorough dispersion; adding solution B, La metal salt, and Ce metal salt in a molar ratio of 1:1:1; controlling the total volume of solution B, La metal salt, and Ce metal salt to about 2ml; evaporating the solution by magnetic stirring at 80℃ for 8h; vacuum drying; and then grinding the solution to obtain precursor powder III.
[0066] Example 8:
[0067] Based on Examples 1-7, step 7 includes: placing the precursor powder III in a Joule heating device and holding it at approximately 1500°C for 10-12 seconds, then rapidly cooling it to room temperature within 5 seconds, and coating the M@αM surface with a high-entropy alloy layer βαM (Ce 1 / 5 La 1 / 5 Ni 1 / 5 Co 1 / 5 Mn 1 / 5 ), thus obtaining a graphite-supported M@αM@βαM high-entropy alloy catalyst.
[0068] Working principle of the invention:
[0069] This invention is based on the recycling technology of spent ternary lithium batteries and utilizes a Joule heating process to prepare a graphite-supported high-entropy alloy catalyst with a built-in electric field, M@αM@βαM. Here, α and β are La-based metals, with α being La and β being one of Ce, Pr, or Nd, and M being one of the three transition metals Ni, Co, and Mn. Graphite carbon powder from the recovered negative electrode material is used as the carbon support, and NiCoMn from the recovered positive electrode material is used as the transition metal source, supplemented by La-based metal salts as the metal source. First, low-entropy alloy nanoparticles (M=NiCoMn) are prepared by co-preparing Ni, Co, and Mn using a Joule heating process. Then, a second Joule heating is used to encapsulate the alloy nanoparticles, constructing an αM medium-entropy alloy layer on their outer layer. Finally, a third Joule heating is used to encapsulate the alloy nanoparticles M@αM a second time, constructing a βαM high-entropy alloy layer on their outer layer. The graphite-supported M@αM@βαM high-entropy alloy catalyst obtained by this method is applied to lithium-oxygen batteries, effectively improving the electrochemical performance of the lithium-oxygen batteries.
[0070] Specifically, a solution rich in NiCoMn metal ions is first recovered from the positive electrode of a spent 111-type ternary lithium-ion battery using methods such as ultrasonication, acid washing, oil bath, and centrifugation. Simultaneously, graphite carbon powder is recovered from the negative electrode of the spent 111-type ternary lithium-ion battery using methods such as Joule heating, acid washing, and centrifugation. The recovered NiCoMn solution and graphite carbon powder are then mixed together in anhydrous ethanol, uniformly dispersed, stirred in an oil bath, evaporated to dryness, and vacuum dried to obtain precursor powder I. Then, Joule heating rapid thermal shock technology is used to hold the powder at 1000-1500℃ for 10-15 seconds, followed by rapid cooling to room temperature within 5-10 seconds. This transient thermal shock, constructed in a short time, allows NiCoMn to combine and form low-entropy alloy nanoparticles M. Subsequently, graphite-supported M@αM low-entropy alloy was mixed with La metal salt and NiCoMn solution in anhydrous ethanol, stirred in an oil bath, evaporated to dryness, and then vacuum dried to obtain precursor powder II. This precursor powder was then subjected to a second Joule heating in a Joule heating apparatus to coat the surface of the alloy nanoparticles M with a layer of αM medium-entropy alloy. Finally, graphite-supported M@αM medium-entropy alloy was mixed uniformly with La metal salt, Ce metal salt, and NiCoMn solution in anhydrous ethanol, stirred in an oil bath, evaporated to dryness, and then vacuum dried to obtain precursor powder III. This precursor powder was then subjected to a third Joule heating in a Joule heating apparatus to coat the surface of the alloy nanoparticles M@αM with a layer of βαM high-entropy alloy. This method yields graphite-supported M@αM@βαM high-entropy alloy catalyst. In the preparation of this graphite-supported M@αM@βαM high-entropy alloy catalyst, valuable metals and negative electrode graphite from waste ternary lithium batteries were effectively utilized. By controlling the Joule heating process, the interaction between the built-in electric field and electron orbitals of the catalyst was realized to enhance catalytic activity, thereby constructing a bifunctional catalyst for lithium-oxygen batteries.
[0071] In summary, this invention provides a method for preparing graphite-supported M@αM@βαM high-entropy alloy catalysts based on the recycling of spent ternary lithium batteries, and applies it to lithium-oxygen batteries. Its advantages are as follows:
[0072] 1. The process involves discharging and dismantling spent lithium-ion batteries, recovering NiCoMn solution from the positive electrode through ultrasonic leaching, centrifugal washing, and oil bath acid washing. The solvent DME used is versatile, has excellent dissolving properties, and is highly safe and environmentally friendly. The potassium carbonate and acetic acid used also exhibit good safety and controllability, aligning with green chemical trends. Graphite carbon powder is recovered through Joule heating carbonization, acid washing, and centrifugal drying. Joule heating is very short and produces minimal impurities. The recovered raw materials are then used to prepare novel catalysts, achieving resource reuse, reducing costs, and minimizing pollution.
[0073] 2. By constructing a three-layer structure (inner, middle, and outer) for the catalyst to generate a built-in electric field, the charge transfer process can be fundamentally optimized, thereby significantly improving catalytic reaction efficiency. The built-in electric field provides the "driving force" for charge transfer by adjusting the electronic state density on the catalyst surface, lowering the transfer energy barrier; it guides and stabilizes the adsorption of reaction intermediates and inhibits the formation of side reaction intermediates by altering the adsorption energy and reaction pathway through potential difference; and it weakens chemical bonds and lowers the activation energy of the reaction through the electric field polarization effect, thus improving catalytic kinetics. In the M@αM@βαM high-entropy alloy catalyst, a "bidirectional radiation from the middle layer" electric field distribution is cleverly constructed, guiding the enrichment of electrons in the middle layer and their transfer to the inner and outer layers respectively, optimizing the charge distribution on the catalyst surface and meeting the requirements of lithium-oxygen battery catalysts for OER / ORR bifunctional catalysis.
[0074] 3. Alloying La-based α and β metals with transition metals M (Ni, Co, Mn) to form M@αM@βαM high-entropy alloy catalysts allows electrons (or empty orbitals) in the rare-earth 4f orbitals to transfer some charge to the 3d orbitals of the transition metals, altering the filling degree of the 3d orbitals. This brings the electronic state density of the 3d orbitals closer to the "optimal energy level" of the catalytic reaction, effectively "charging" the "active center" and enhancing the adsorption and activation capacity of reaction molecules. The strong localization properties of the 4f orbitals anchor the positions of transition metal atoms, inhibiting their aggregation during the reaction; simultaneously, the ductility of the 3d orbitals maintains the conductivity of the alloy structure. In the OER process, this weakens the excessive adsorption of reaction intermediates, preventing the active sites from being "poisoned" and lowering the reaction activation energy; in the ORR process, it enhances the selectivity of the ORR reaction and reduces the formation of by-products.
[0075] 4. High-entropy ordered alloys formed by five or more principal elements possess abundant and tunable catalytic active sites. Multi-element synergy can construct active centers, adapting to the adsorption requirements of reaction intermediates. The high-entropy effect enhances corrosion resistance and improves thermodynamic stability. The ordered structure allows active element atoms to be uniformly distributed on specific crystal planes, avoiding the problem of "inert element shielding" and preventing segregation and aggregation of active elements due to high temperature or electrolyte erosion during the reaction, thus extending catalyst lifetime. Simultaneously, numerous lattice distortions form on the alloy surface, generating abundant active sites. As key sites for the oxygen reduction (ORR) / oxygen evolution (OER) reaction, these sites facilitate the adsorption and desorption of oxygen molecules and intermediates, effectively improving ORR / OER reaction efficiency.
[0076] 5. This method has a simple synthesis process, environmentally friendly raw material recovery, low cost of La-based metals, and the possibility of large-scale production. It is highly versatile and beneficial for performance improvement and practical application in lithium-oxygen batteries.
Claims
1. A method for preparing graphite-supported high-entropy alloy catalysts with built-in electric fields M@αM@βαM using spent ternary lithium batteries, characterized in that, Includes the following steps: Step 1: Discharge and disassemble the waste ternary lithium battery to recover graphite carbon powder A from the negative electrode copper sheet and NiCoMn ion solution B from the positive electrode. Step 2: Mix the recovered NiCoMn solution B and graphite carbon powder A together in anhydrous ethanol, stir to adsorb evenly, evaporate to dryness, grind and dry to obtain precursor powder I; Step 3: Precursor powder I is subjected to Joule thermal shock in a Joule heating apparatus to obtain graphite-loaded M, i.e., Ni. 1 / 3 Co 1 / 3Mn 1 / 3 Low-entropy alloys; Step 4: Load graphite with M, i.e., Ni. 1 / 3 Co 1 / 3 Mn 1 / 3 The low-entropy alloy was mixed with La metal salt and NiCoMn solution B in anhydrous ethanol, stirred until uniformly adsorbed, evaporated and ground to obtain precursor powder II. Step 5: The precursor powder II is subjected to secondary Joule heating, and a medium-entropy alloy layer αM, namely La, is successfully coated onto the surface of the low-entropy alloy M through thermal shock. 1 / 4 Ni 1 / 4 Co 1 / 4 Mn 1 / 4 , thus obtaining a graphite-supported M@αM medium-entropy alloy; Step 6: Mix the graphite-supported M@αM medium-entropy alloy with La metal salt, Ce metal salt, and NiCoMn solution B in anhydrous ethanol until homogeneous, stir to adsorb evenly, evaporate to dryness, grind and dry to obtain precursor powder III. Step 7: The precursor powder III is fed into a Joule heating device for three Joule heatings. Through thermal shock, a high-entropy alloy layer βαM, namely Ce, is successfully coated onto the surface of the M@αM medium-entropy alloy. 1 / 5 La 1 / 5 Ni 1 / 5 Co 1 / 5 Mn 1 / 5 A graphite-supported M@αM@βαM high-entropy alloy catalyst was prepared.
2. The method for preparing a graphite-supported high-entropy alloy catalyst with a built-in electric field M@αM@βαM using spent ternary lithium batteries as described in claim 1, characterized in that, Step 1 includes: (1) After the waste ternary lithium battery is fully discharged, it is disassembled, the negative electrode is peeled off and taken out, cut into small pieces of 5cm*1cm, wrapped with carbon paper and placed in a Joule heating device for thermal shock. After holding at about 800℃ for 5-10s to carbonize the binder, the graphite is scraped off and ground, and then acid-leached with 5M-10M nitric acid, washed with water, centrifuged, and vacuum dried to obtain the recycled graphite carbon powder A. (2) After stripping the NiCoMn-containing cathode, cut it into 5cm*1cm pieces and place it in ethylene glycol dimethyl ether (DME) solution and sonicate for 15-20h, keeping the temperature below 30℃ during the process; centrifuge and dry the obtained leachate to obtain powder containing LiNiCoMn; place the powder in 5M-10M potassium carbonate solution and stir in an oil bath at 50-60℃ for 2-5h, then centrifuge and wash with water to remove lithium impurities to obtain NiCoMn carbonate precipitate; add the precipitate to 5M acetic acid solution, stir thoroughly to dissolve, centrifuge and take the supernatant to obtain solution B containing NiCoMn ions.
3. The method for preparing a graphite-supported high-entropy alloy catalyst with a built-in electric field M@αM@βαM using spent ternary lithium batteries as described in claim 2, characterized in that, Step 2 includes: Take 500 mg of graphite carbon powder A and an appropriate amount of solution B and mix them in 50 ml of anhydrous ethanol. The volume of solution B should be controlled at about 10 mL. Stir magnetically at 80 °C for 8 h and evaporate to dryness. After vacuum drying, take it out and grind it to obtain precursor powder I.
4. The method for preparing a graphite-supported high-entropy alloy catalyst with a built-in electric field M@αM@βαM using spent ternary lithium batteries as described in claim 3, characterized in that, Step 3 includes: Precursor powder I was placed in a Joule heating apparatus and held at approximately 1500°C for 10-12 seconds, then rapidly cooled to room temperature within 5 seconds to obtain graphite-supported M, i.e., Ni. 1 / 3 Co 1 / 3 Mn 1 / 3 Low-entropy alloys.
5. The method for preparing a graphite-supported high-entropy alloy catalyst with a built-in electric field M@αM@βαM using spent ternary lithium batteries as described in claim 4, characterized in that, Step 4 includes: taking 300mg of graphite-supported M low-entropy alloy powder and dispersing it fully in 40ml of anhydrous ethanol; adding solution B and La metal salt in a molar ratio of 1:1; controlling the total volume of solution B and La metal salt to about 6ml; evaporating the solution by magnetic stirring at 80℃ for 8h; vacuum drying; and then grinding the solution to obtain precursor powder II.
6. The method for preparing a graphite-supported high-entropy alloy catalyst with a built-in electric field M@αM@βαM using spent ternary lithium batteries as described in claim 5, characterized in that, Step 5 includes: placing precursor powder II in a Joule heating device and holding it at approximately 1500°C for 10-12 seconds, then rapidly cooling it to room temperature within 5 seconds, and coating the surface of the low-entropy alloy M with a medium-entropy alloy layer αM, i.e., La. 1 / 4 Ni 1 / 4 Co 1 / 4 Mn 1 / 4 , thus obtaining a graphite-supported M@αM medium-entropy alloy.
7. The method for preparing a graphite-supported high-entropy alloy catalyst with a built-in electric field M@αM@βαM using spent ternary lithium batteries as described in claim 6, characterized in that, Step 6 includes: taking 100mg of graphite-supported M@αM medium-entropy alloy powder and adding it to 40ml of anhydrous ethanol for thorough dispersion; adding solution B, La metal salt, and Ce metal salt in a molar ratio of 1:1:1; controlling the total volume of solution B, La metal salt, and Ce metal salt to about 2ml; evaporating the solution by magnetic stirring at 80℃ for 8h; vacuum drying; and then grinding the solution to obtain precursor powder III.
8. The method for preparing a graphite-supported high-entropy alloy catalyst with a built-in electric field M@αM@βαM using spent ternary lithium batteries as described in claim 7, characterized in that, Step 7 includes: placing the precursor powder III in a Joule heating device and holding it at approximately 1500°C for 10-12 seconds, then rapidly cooling it to room temperature within 5 seconds, and coating the M@αM surface with a high-entropy alloy layer βαM, i.e., Ce. 1 / 5 La 1 / 5 Ni 1 / 5 Co 1 / 5 Mn 1 / 5 A graphite-supported M@αM@βαM high-entropy alloy catalyst was obtained.