A method for preparing high-entropy electrode materials to improve the cycling performance of supercapacitors

Abstract

This invention relates to the field of electrode material technology, specifically to a method for preparing a high-entropy electrode material to improve the cycle performance of supercapacitors. The method includes the following steps: dissolving cobalt salt, nickel salt, manganese salt, iron salt, and magnesium salt in deionized water; adding a carbon source, urea, and a surfactant; stirring until homogeneous; and conducting a hydrothermal reaction to obtain the high-entropy electrode material. The high-entropy electrode material prepared by this invention has an open layered structure, allowing rapid movement of electrolyte ions between layers, ensuring high rate performance. The synergistic effect of multiple elements improves electrochemical performance, meeting the practical requirements of supercapacitors.

Description

Technical Field

[0001] This invention relates to the field of electrode material technology, specifically a method for preparing high-entropy electrode materials to improve the cycling performance of supercapacitors. Background Technology

[0002] Supercapacitors are indispensable in fields such as new energy vehicles, smart grids, and wearable devices due to their high power density, fast charging and discharging, and ultra-long cycle life.

[0003] Traditional electrode materials, such as activated carbon, transition metal oxides or hydroxides, and conductive polymers, have approached their theoretical limits in terms of single performance indicators. Developing novel electrode materials has become a research hotspot in this field, with high-entropy materials attracting widespread attention due to their advantages such as large capacity and high stability. In summary, this invention proposes a method for preparing high-entropy electrode materials to improve the cycling performance of supercapacitors by introducing LDH (layered double hydroxide) to enhance rate performance. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing high-entropy electrode materials to improve the cycling performance of supercapacitors, thereby solving the related technical problems existing in the prior art.

[0005] To achieve the above objectives, the present invention provides the following specific technical solutions: A method for preparing a high-entropy electrode material to improve the cycle performance of a supercapacitor includes the following process steps: dissolving cobalt salt, nickel salt, manganese salt, iron salt, and magnesium salt in deionized water, adding carbon source, urea, and surfactant, stirring evenly, and carrying out a hydrothermal reaction to obtain a modified CoNiMnFeMgLDH material, which is the high-entropy electrode material.

[0006] In a more optimized manner, the modified CoNiMnFeMgLDH material is prepared by the following process: Cobalt salt Co(NO3)2 (cobalt nitrate), nickel salt Ni(NO3)2 (nickel nitrate), manganese salt Mn(NO3)2 (manganese nitrate), iron salt Fe(NO3)3 (iron nitrate), and magnesium salt Mg(NO3)2 (magnesium nitrate) are dissolved in deionized water to form a metal salt solution. Carbon source glucose, urea, and surfactant polyethylene glycol (PEG) were added sequentially to a metal salt solution, stirred until homogeneous, and heated to carry out a hydrothermal reaction. After the reaction was completed, the mixture was centrifuged, filtered, washed, and vacuum dried to obtain the modified CoNiMnFeMgLDH material.

[0007] Ideally, the hydrothermal reaction process conditions are as follows: heating the reaction at a temperature of 125~135℃ for 8~12 hours.

[0008] The optimal molar ratio of Co(NO3)2, Ni(NO3)2, Mn(NO3)2, Fe(NO3)3, and Mg(NO3)2 is (0.5~2):(0.5~2):(0.5~2):(0.5~2).

[0009] Ideally, the molar ratio of urea to the total molar ratio of metal ions is 1:(1~2).

[0010] Ideally, the molar ratio of glucose to total metal ions is 1:(1~3).

[0011] Ideally, the molar ratio of PEG to total metal ions is 1:(85~115).

[0012] Ideally, the vacuum drying process conditions are as follows: drying at 60~70℃ for 3~4 hours.

[0013] In the above technical solution, the present invention uses a one-step hydrothermal synthesis method to synthesize modified CoNiMnFeMgLDH material. The LDH material has an open layered structure, allowing rapid movement of electrolyte ions between layers, ensuring high rate performance; Ni provides the overall capacity of the material; Co element optimizes the conductivity of the material, while stabilizing the high valence state of Ni, such as Ni 4+ Mn provides a rich variety of valence state changes, such as Mn 3+ or Mn 4+ This increases capacity and widens the operating potential window; Fe not only effectively modulates the local electronic structure and enhances structural stability, but also... 2+ or Fe 3+ Capacity contribution also exists during the conversion process; inert Mg 2+ The five elements work synergistically to stabilize the layered structure of LDH and suppress volume expansion and structural collapse during continuous charge-discharge cycles, ensuring not only the capacity and kinetic behavior of the active material but also stabilizing the layered structure. From the perspective of improving conductivity, the modified CoNiMnFeMgLDH material incorporates glucose (a carbon source) and polyethylene glycol (a surfactant) during the hydrothermal process. The glucose decomposes upon heating, creating conductive pathways within and between LDH particles, significantly enhancing the overall electrode's electronic conductivity. The small amount of surfactant introduced utilizes steric hindrance to adsorb onto the surface of newly formed crystal particles, effectively preventing nanoparticle aggregation and avoiding the reduction of active sites caused by aggregation. Urea acts as a precipitant, slowly hydrolyzing and releasing hydroxide ions under heating conditions to achieve simultaneous and uniform co-precipitation of multi-component metal ions.

[0014] In a more optimized manner, the metal salt solution also contains a composite biomass porous carbon carrier dispersed in it, with the mass ratio of the composite biomass porous carbon carrier to the total mass of metal ions being 0.5:(10~20).

[0015] In a more optimized manner, the composite biomass porous carbon carrier is added in the form of a dispersion, which is prepared by mixing and dispersing the composite biomass porous carbon carrier and deionized water.

[0016] Ideally, the mass ratio of the composite biomass porous carbon carrier to deionized water is 1:(20~30).

[0017] In a more optimized manner, the composite biomass porous carbon carrier is prepared by the following process: graphene oxide and biomass carbon are added to a low-temperature eutectic active molten salt system, stirred evenly, heated to 290-300°C in a N2 atmosphere at a heating rate of 6-8°C / min, held at the temperature for 1-2 hours, filtered, washed until neutral, and dried to obtain the composite biomass porous carbon carrier.

[0018] The optimal mass ratio of graphene oxide, biomass carbon, and low-temperature eutectic active molten salt system is 1:(2~3):(25~30).

[0019] In a more optimized manner, the low-temperature eutectic active molten salt system is a mixture of sodium hydroxide and sodium carbonate, with a mass ratio of sodium hydroxide to sodium carbonate of (6~7):1.

[0020] Ideally, the biomass carbon is any one of coconut shell carbon, bamboo-based carbon, or corn cob carbon.

[0021] In the above technical solution, biomass carbon has a natural porous structure, a high degree of fibrosis, and is widely available and inexpensive, combining structural advantages with sustainability. A low-temperature eutectic active molten salt system is used to remove oxygen-containing functional groups from the surfaces of graphene and biomass carbon materials. Sodium hydroxide and sodium carbonate are used as etchants to form nanopores in the carbon layer, increasing the specific surface area and enriching the microporous structure of its surface or internal structure, forming a three-dimensional porous carbon material that provides a supporting framework. Biomass carbon provides a layered porous framework; its porous characteristics and large specific surface area provide ample space for LDH loading, facilitating rapid electrolyte penetration and ion transport, and improving energy storage performance. The combination of graphene oxide and biomass carbon produces a significant synergistic enhancement effect, making the overall performance of the composite biomass porous carbon carrier superior to the combination of graphene oxide and biomass carbon alone. The composite biomass porous carbon carrier is added in the form of a dispersion to prevent agglomeration and improve system uniformity.

[0022] In a more optimized manner, the modified CoNiMnFeMgLDH material undergoes post-treatment.

[0023] In a more optimized manner, the post-processing specifically includes the following steps: adding sodium sulfide to deionized water, sonicating at a power of 30~40W for 15~20min, adding modified CoNiMnFeMgLDH material, stirring evenly, reacting at a temperature of 120~130℃ for 3~4h, and after the reaction is completed, cooling to room temperature, filtering, and drying.

[0024] In the above technical solution, the present invention uses sodium sulfide to post-treat the modified CoNiMnFeMgLDH material, and anion exchange and in-situ sulfidation reaction occur under heating conditions. Sulfur element is loaded at the edge or defect of LDH material. Sulfur has a lower electronegativity than oxygen. By utilizing a variety of metal elements, the electronic structure of the electrode material is reconstructed, the microstructure of LDH material is adjusted, the lattice collapse or phase transition during cycling is prevented, the charge transport between layers is promoted, and the specific capacity, rate performance and other electrochemical performance of the electrode material are improved.

[0025] The optimal mass ratio of sodium sulfide, modified CoNiMnFeMgLDH material, and deionized water is (1~3):(5~8):(20~25).

[0026] Ideally, the centrifugation process conditions are as follows: centrifugation at a speed of 2000~2400 r / min for 5~10 min.

[0027] The optimal drying process conditions are: drying at 60~70℃ for 2~3 hours.

[0028] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention employs a one-step hydrothermal synthesis method to synthesize modified CoNiMnFeMgLDH materials. Their layered structure ensures high rate performance. Simultaneously, all exposed transition metal cations on the material surface are potential redox active sites. Ni provides the overall capacity of the material; Co optimizes the material's conductivity and stabilizes the high valence state of Ni; Mn provides abundant valence state variations, increasing additional capacity and widening the operating potential window; Fe not only effectively modulates the local electronic structure and enhances structural stability, but also... 2+ or Fe 3+ Capacity contribution also exists during the conversion process; inert Mg 2+ The layered structure of LDH is stabilized, suppressing volume expansion and structural collapse during continuous charge-discharge cycles. The synergistic effect of multiple elements not only ensures the capacity and kinetic behavior of the active material, but also stabilizes the layered structure and improves the electrochemical performance of the electrode material.

[0029] 2. This invention uses a low-temperature eutectic active molten salt system to treat graphene oxide and biomass carbon, enriching the microporous structure and forming a three-dimensional porous carbon material to provide a supporting framework. Biomass carbon provides a layered porous framework, and its porous characteristics and large specific surface area provide sufficient space for LDH loading, which is conducive to rapid electrolyte penetration and ion transport, thereby improving energy storage performance.

[0030] 3. In this invention, sodium sulfide is used to post-treat the modified CoNiMnFeMgLDH material, and anion exchange and in-situ sulfidation reaction occur under heating conditions to improve the specific capacity, rate performance and other electrochemical properties of the electrode material. Detailed Implementation

[0031] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. It should be understood that the embodiments described herein are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the protection scope of the present invention; unless otherwise specified, the related raw materials are all conventional settings.

[0032] In the following embodiments, there are no special limitations on any of the raw materials involved in this invention, and the following raw materials are included by way of example: PEG, model: PEG-4000; Adhesive, PVDF, grade: Solvay 5130; Conductive agent, SuperP, brand: Swiss company SuperP. Graphene oxide, model: XFSG01; Biomass charcoal, coconut shell charcoal, specific surface area 500 m² 2 / g, micropore capacity >80%, average particle size 80μm; A low-temperature eutectic active molten salt system, consisting of a mixture of sodium hydroxide and sodium carbonate, with a mass ratio of sodium hydroxide to sodium carbonate of 6:1. Example

[0033] A method for preparing a high-entropy electrode material to improve the cycling performance of supercapacitors includes the following steps: 0.01 mol of Co(NO3)2·6H2O, 0.01 mol of Ni(NO3)2·6H2O, 0.01 mol of Mn(NO3)2·6H2O, 0.01 mol of Fe(NO3)3·9H2O, and 0.01 mol of Mg(NO3)2·6H2O are weighed and dissolved in 200 mL of deionized water. Then, 0.025 mol of glucose, 0.05 mol of urea, and 0.5 mol of PEG are added sequentially, stirred evenly, and heated at 130 °C for 12 h. After the reaction is completed, the mixture is centrifuged at 2000 r / min for 10 min and then vacuum dried at 60 °C for 3 h to obtain the modified CoNiMnFeMgLDH material. Example

[0034] A method for preparing a high-entropy electrode material to improve the cycling performance of a supercapacitor, wherein the amount of glucose added is 0.05 mol; the remaining process parameters are the same as in Example 1. Example

[0035] A method for preparing a high-entropy electrode material to improve the cycling performance of a supercapacitor, wherein the amount of glucose added is 0.017 mol; the remaining process parameters are the same as in Example 1. Example

[0036] A method for preparing a high-entropy electrode material to improve the cycling performance of supercapacitors, wherein the amount of PEG added is 0.56 mmol; the remaining process parameters are the same as in Example 1. Example

[0037] A method for preparing a high-entropy electrode material to improve the cycling performance of supercapacitors, wherein the amount of PEG added is 0.45 mmol; the remaining process parameters are the same as in Example 1. Example

[0038] A method for preparing high-entropy electrode materials to improve the cycling performance of supercapacitors, wherein the addition amounts of Co(NO3)2·6H2O, Ni(NO3)2·6H2O, Mn(NO3)2·6H2O, Fe(NO3)3·9H2O, and Mg(NO3)2·6H2O are 0.005 mol, 0.01 mol, 0.01 mol, 0.01 mol, and 0.01 mol, respectively; the remaining process parameters are the same as in Example 1. Example

[0039] A method for preparing high-entropy electrode materials to improve the cycling performance of supercapacitors, wherein the addition amounts of Co(NO3)2·6H2O, Ni(NO3)2·6H2O, Mn(NO3)2·6H2O, Fe(NO3)3·9H2O, and Mg(NO3)2·6H2O are 0.02 mol, 0.01 mol, 0.01 mol, 0.01 mol, and 0.01 mol, respectively; the remaining process parameters are the same as in Example 1. Example

[0040] A method for preparing high-entropy electrode materials to improve the cycling performance of supercapacitors, wherein the amounts of Co(NO3)2·6H2O, Ni(NO3)2·6H2O, Mn(NO3)2·6H2O, Fe(NO3)3·9H2O, and Mg(NO3)2·6H2O added are 0.01 mol, 0.005 mol, 0.01 mol, 0.01 mol, and 0.01 mol, respectively; the remaining process parameters are the same as in Example 1. Example

[0041] A method for preparing high-entropy electrode materials to improve the cycling performance of supercapacitors, wherein the amounts of Co(NO3)2·6H2O, Ni(NO3)2·6H2O, Mn(NO3)2·6H2O, Fe(NO3)3·9H2O, and Mg(NO3)2·6H2O added are 0.01 mol, 0.02 mol, 0.01 mol, 0.01 mol, and 0.01 mol, respectively; the remaining process parameters are the same as in Example 1.

[0042] Example 10: A method for preparing high-entropy electrode materials to improve the cycling performance of supercapacitors, wherein the amounts of Co(NO3)2·6H2O, Ni(NO3)2·6H2O, Mn(NO3)2·6H2O, Fe(NO3)3·9H2O, and Mg(NO3)2·6H2O added are 0.01 mol, 0.01 mol, 0.005 mol, 0.01 mol, and 0.01 mol, respectively; the remaining process parameters are the same as in Example 1.

[0043] Example 11: A method for preparing high-entropy electrode materials to improve the cycling performance of supercapacitors, wherein the amounts of Co(NO3)2·6H2O, Ni(NO3)2·6H2O, Mn(NO3)2·6H2O, Fe(NO3)3·9H2O, and Mg(NO3)2·6H2O added are 0.01 mol, 0.01 mol, 0.02 mol, 0.01 mol, and 0.01 mol, respectively; the remaining process parameters are the same as in Example 1.

[0044] Example 12: A method for preparing high-entropy electrode materials to improve the cycling performance of supercapacitors, wherein the amounts of Co(NO3)2·6H2O, Ni(NO3)2·6H2O, Mn(NO3)2·6H2O, Fe(NO3)3·9H2O, and Mg(NO3)2·6H2O added are 0.01 mol, 0.01 mol, 0.01 mol, 0.005 mol, and 0.01 mol, respectively; the remaining process parameters are the same as in Example 1.

[0045] Example 13: A method for preparing high-entropy electrode materials to improve the cycling performance of supercapacitors, wherein the amounts of Co(NO3)2·6H2O, Ni(NO3)2·6H2O, Mn(NO3)2·6H2O, Fe(NO3)3·9H2O, and Mg(NO3)2·6H2O added are 0.01 mol, 0.01 mol, 0.01 mol, 0.02 mol, and 0.01 mol, respectively; the remaining process parameters are the same as in Example 1.

[0046] Example 14: A method for preparing high-entropy electrode materials to improve the cycling performance of supercapacitors, wherein the amounts of Co(NO3)2·6H2O, Ni(NO3)2·6H2O, Mn(NO3)2·6H2O, Fe(NO3)3·9H2O, and Mg(NO3)2·6H2O added are 0.01 mol, 0.01 mol, 0.01 mol, 0.01 mol, and 0.005 mol, respectively; the remaining process parameters are the same as in Example 1.

[0047] Example 15: A method for preparing high-entropy electrode materials to improve the cycling performance of supercapacitors, wherein the addition amounts of Co(NO3)2·6H2O, Ni(NO3)2·6H2O, Mn(NO3)2·6H2O, Fe(NO3)3·9H2O, and Mg(NO3)2·6H2O are 0.005 mol, 0.01 mol, 0.01 mol, 0.01 mol, and 0.02 mol, respectively; the remaining process parameters are the same as in Example 1.

[0048] Example 16: A method for preparing a high-entropy electrode material to improve the cycling performance of a supercapacitor includes the following steps: 0.01 mol of Co(NO3)2·6H2O, 0.01 mol of Ni(NO3)2·6H2O, 0.01 mol of Mn(NO3)2·6H2O, 0.01 mol of Fe(NO3)3·9H2O, and 0.01 mol of Mg(NO3)2·6H2O are weighed and dissolved in 200 mL of deionized water. 10 mL of composite biomass porous carbon carrier dispersion, 0.025 mol of glucose, 0.05 mol of urea, and 0.5 mol of PEG are added sequentially, stirred evenly, and heated to 130 °C for 8 h. After the reaction, the mixture is centrifuged at 2000 r / min for 10 min, and then vacuum dried at 60 °C for 3 h. After post-treatment, modified CoNiMnFeMgLDH material is obtained. The composite biomass porous carbon carrier dispersion was prepared by mixing 1g of composite biomass porous carbon carrier and 20mL of deionized water and dispersing at 2000r / min for 10min. The composite biomass porous carbon carrier is prepared by the following process: 1g of graphene oxide and 2g of biomass carbon are added to 25g of low-temperature eutectic active molten salt system, stirred evenly, heated to 300℃ at a heating rate of 6℃ / min in N2 atmosphere, kept at the temperature for 1h, filtered, washed until neutral, and dried at 60℃ for 2h to obtain the composite biomass porous carbon carrier. The post-processing specifically includes the following steps: add 1g of sodium sulfide to 20mL of deionized water, sonicate at 30W for 15min, add 5g of modified CoNiMnFeMgLDH material, stir evenly, react at 120℃ for 3h, after the reaction is completed, cool to room temperature, filter, and dry at 60℃ for 2h.

[0049] Example 17: A method for preparing a high-entropy electrode material to improve the cycling performance of a supercapacitor includes the following steps: 0.01 mol of Co(NO3)2·6H2O, 0.01 mol of Ni(NO3)2·6H2O, 0.01 mol of Mn(NO3)2·6H2O, 0.01 mol of Fe(NO3)3·9H2O, and 0.01 mol of Mg(NO3)2·6H2O are weighed and dissolved in 200 mL of deionized water. 10 mL of composite biomass porous carbon carrier dispersion, 0.025 mol of glucose, 0.05 mol of urea, and 0.5 mol of PEG are added sequentially, stirred evenly, and heated to react at 130 °C for 10 h. After the reaction, the mixture is centrifuged at 2000 r / min for 10 min, and then vacuum dried at 60 °C for 3 h. After post-treatment, modified CoNiMnFeMgLDH material is obtained. The composite biomass porous carbon carrier dispersion was prepared by mixing 1g of composite biomass porous carbon carrier and 20mL of deionized water and dispersing at 2000r / min for 10min. The composite biomass porous carbon carrier was prepared by the following process: 1g of graphene oxide and 2.5g of biomass carbon were added to 27.5g of low-temperature eutectic active molten salt system, stirred evenly, and then heated to 300℃ at a heating rate of 6℃ / min in N2 atmosphere, held at the temperature for 1.5h, filtered, washed until neutral, and dried at 60℃ for 2h to obtain the composite biomass porous carbon carrier. The post-processing specifically includes the following steps: 1g of sodium sulfide is added to 20mL of deionized water and sonicated at 35W for 18min. 5g of modified CoNiMnFeMgLDH material is added and stirred evenly. The mixture is reacted at 120℃ for 3h. After the reaction is completed, the mixture is cooled to room temperature, filtered, washed, and dried at 60℃ for 2h.

[0050] Example 18: A method for preparing a high-entropy electrode material to improve the cycling performance of a supercapacitor includes the following steps: 0.01 mol of Co(NO3)2·6H2O, 0.01 mol of Ni(NO3)2·6H2O, 0.01 mol of Mn(NO3)2·6H2O, 0.01 mol of Fe(NO3)3·9H2O, and 0.01 mol of Mg(NO3)2·6H2O are weighed and dissolved in 200 mL of deionized water. 10 mL of composite biomass porous carbon carrier dispersion, 0.025 mol of glucose, 0.05 mol of urea, and 0.5 mol of PEG are added sequentially, stirred evenly, and heated to react at 130 °C for 12 h. After the reaction is completed, the mixture is centrifuged at 2000 r / min for 10 min, and then vacuum dried at 60 °C for 3 h. After post-treatment, modified CoNiMnFeMgLDH material is obtained. The composite biomass porous carbon carrier dispersion was prepared by mixing 1g of composite biomass porous carbon carrier and 20mL of deionized water and dispersing at 2000r / min for 10min. The composite biomass porous carbon carrier is prepared by the following process: 1g of graphene oxide and 3g of biomass carbon are added to 30g of low-temperature eutectic active molten salt system, stirred evenly, heated to 300℃ at a heating rate of 8℃ / min in N2 atmosphere, kept at the temperature for 2h, filtered, washed until neutral, and dried at 60℃ for 2h to obtain the composite biomass porous carbon carrier. The post-processing specifically includes the following steps: 1g of sodium sulfide is added to 20mL of deionized water and sonicated at 40W for 20min. 5g of modified CoNiMnFeMgLDH material is added and stirred evenly. The mixture is reacted at 130℃ for 4h. After the reaction is completed, the mixture is cooled to room temperature, filtered, washed, and dried at 60℃ for 2h.

[0051] Comparative Example 1: A method for preparing a high-entropy electrode material, wherein glucose is not added in the preparation method of modified CoNiMnFeMgLDH material, and the remaining process parameters are the same as in Example 1.

[0052] Comparative Example 2: A method for preparing a high-entropy electrode material, wherein the modified CoNiMnFeMgLDH material is prepared without the addition of PEG, and the remaining process parameters are the same as in Example 1.

[0053] Comparative Example 3: A method for preparing a high-entropy electrode material, wherein glucose and PEG are not added in the preparation method of modified CoNiMnFeMgLDH material, and the remaining process parameters are the same as in Example 1.

[0054] Comparative Example 4: A method for preparing a high-entropy electrode material, wherein the preparation method of modified CoNiMnFeMgLDH material does not involve post-treatment, and the remaining process parameters are the same as in Example 16.

[0055] Comparative Example 5: A method for preparing a high-entropy electrode material, specifically a modified CoNiMnFeMgLDH material, involves replacing the composite biomass porous carbon carrier dispersion with a dispersion of biomass carbon and graphene oxide. The biomass carbon and graphene oxide are mixed with deionized water and dispersed at 2000 r / min for 10 min. The mass ratio of biomass carbon, graphene oxide, and deionized water is 2:1:20. The remaining process parameters are the same as in Example 16.

[0056] Experimental test: The electrode materials prepared in Examples 1-18 and Comparative Examples 1-5 were used as samples for performance testing: Preparation of electrode sheet: The electrode material is used as the active material. The active material, binder and conductive agent are mixed in a mass ratio of 8:1:1. After being mixed evenly, the mixture is coated on carbon paper and dried under vacuum at 60°C for 12 hours to obtain the electrode sheet. Rate performance testing method: A three-electrode testing system and an electrochemical workstation were used for GCD (constant current charge-discharge) testing. The electrolyte in the electrolytic cell was a 1M KOH solution. The reference electrode was an Ag / AgCl electrode, the counter electrode was a Pt electrode, and the working electrode was an electrode plate coated with active material. The working voltage range was 0V~0.5V. The specific capacity and capacity retention were tested at current densities of 1A / g, 2A / g, and 5A / g.

[0057] Cyclic performance testing method: A three-electrode testing system and an electrochemical workstation were used for GCD (constant current charge-discharge) testing. The electrolyte in the electrolytic cell was a 1M KOH solution. The reference electrode was an Ag / AgCl electrode, the counter electrode was a Pt electrode, and the working electrode was an electrode plate coated with active material. The working voltage range was 0V~0.5V, and the capacity retention rate was tested at a current density of 1A / g for 100 cycles.

[0058] The experimental data are as follows: Table 1

[0059] Results and Discussion: The data in the table above show that: The modified CoNiMnFeMgLDH material of this application has a large specific capacity, high capacity retention, and excellent electrochemical performance.

[0060] Compared with Example 1, in the preparation method of the modified CoNiMnFeMgLDH material in Comparative Example 1, without the addition of glucose, the specific capacity and capacity retention rate both decreased significantly, indicating that the amorphous carbon three-dimensional conductive network formed by glucose decomposition plays a key role in improving electronic conduction and rate performance.

[0061] Compared with Example 1, in the preparation method of the modified CoNiMnFeMgLDH material in Comparative Example 2, PEG was not added, and the specific capacity and capacity retention rate decreased slightly. This indicates that PEG, as a surfactant, can effectively inhibit the aggregation of nanoparticles, reduce the loss of active sites, and is beneficial to the dispersibility and electrochemical activity of the material.

[0062] Compared with Example 1, the preparation method of the modified CoNiMnFeMgLDH material in Comparative Example 3, without the addition of glucose and PEG, showed the most significant decrease in specific capacity and capacity retention, verifying the important influence of the synergistic effect of the conductive network and the dispersing stabilizer on the electrochemical performance of the high-entropy electrode material.

[0063] Compared with Example 16, the specific capacity and retention rate of the modified CoNiMnFeMgLDH material in Comparative Example 4, without post-treatment, are lower than those in Example 16. This indicates that the anion exchange and in-situ sulfidation reaction caused by sodium sulfide post-treatment can effectively reconstruct the electronic structure, suppress lattice collapse, and significantly improve the conductivity and cycle stability of the material.

[0064] Compared with Example 16, Comparative Example 5 used unmodified graphene oxide and biomass carbon in a simple mixture without molten salt activation. The specific capacity and retention rate were significantly lower than those of Example 16, indicating that low-temperature eutectic molten salt activation can significantly enhance the specific surface area, pore structure and hydrophobic stability of porous carbon supports, thereby improving LDH loading efficiency and ion transport capacity.

[0065] For those skilled in the art, it is obvious that the present invention is not limited to the details disclosed in the exemplary embodiments described above. The present invention can be implemented in other specific ways without departing from its spirit and essential characteristics. Therefore, the foregoing embodiments should be considered exemplary rather than restrictive from any perspective. The scope of protection of the present invention is defined by the appended claims. Therefore, all variations falling within the meaning and scope of the equivalent elements of the claims should be attributed to the scope of the present invention.

Claims

1. A method for preparing a high-entropy electrode material to improve the cycling performance of a supercapacitor, characterized in that: The process includes the following steps: dissolving cobalt salt, nickel salt, manganese salt, iron salt, and magnesium salt in deionized water, adding carbon source, urea, and surfactant, and carrying out a hydrothermal reaction to obtain modified CoNiMnFeMgLDH material, which is a high-entropy electrode material; the molar ratio of cobalt ions, nickel ions, manganese ions, iron ions, and magnesium ions is (0.5~2):(0.5~2):(0.5~2):(0.5~2):(0.5~2).

2. The method for preparing a high-entropy electrode material to improve the cycling performance of a supercapacitor according to claim 1, characterized in that: The modified CoNiMnFeMgLDH material is prepared by the following process: Cobalt salts (cobalt nitrate), nickel salts (nickel nitrate), manganese salts (manganese nitrate), iron salts (iron nitrate), and magnesium salts (magnesium nitrate) are dissolved in deionized water to form metal salt solutions. Carbon source glucose, urea, and surfactant polyethylene glycol were added sequentially to a metal salt solution, stirred until homogeneous, and heated to carry out a hydrothermal reaction. After the reaction was completed, the solution was centrifuged, filtered, washed, and vacuum dried to obtain the modified CoNiMnFeMgLDH material.

3. The method for preparing a high-entropy electrode material to improve the cycling performance of a supercapacitor according to claim 2, characterized in that: The molar ratio of glucose to total metal ions is 1:(1~3).

4. The method for preparing a high-entropy electrode material to improve the cycling performance of a supercapacitor according to claim 2, characterized in that: The molar ratio of polyethylene glycol to total metal ions is 1: (85~115).

5. The method for preparing a high-entropy electrode material to improve the cycling performance of a supercapacitor according to claim 2, characterized in that: The molar ratio of urea to the total molar ratio of metal ions is 1:(1~2).

6. The method for preparing a high-entropy electrode material to improve the cycle performance of a supercapacitor according to claim 2, characterized in that: The hydrothermal reaction process conditions are: reaction at 125~135℃ for 8~12h.

7. The method for preparing a high-entropy electrode material to improve the cycling performance of a supercapacitor according to claim 3, characterized in that: The metal salt solution also contains a composite biomass porous carbon carrier, and the mass ratio of the composite biomass porous carbon carrier to the total mass of metal ions is 0.5: (10~20).

8. The method for preparing a high-entropy electrode material to improve the cycling performance of a supercapacitor according to claim 7, characterized in that: The composite biomass porous carbon carrier is prepared by the following process: Graphene oxide and biomass carbon were added to a low-temperature eutectic active molten salt system, and the temperature was raised to 290~300℃ in N2 atmosphere and kept at the temperature for 1~2h for activation. After activation, the mixture was filtered, washed until neutral, and dried to obtain a composite biomass porous carbon carrier. The mass ratio of graphene oxide, biomass carbon, and low-temperature eutectic active molten salt system is 1:(2~3):(25~30); The low-temperature eutectic active molten salt system is a mixture of sodium hydroxide and sodium carbonate, with a mass ratio of sodium hydroxide to sodium carbonate of (6~7):1; The biomass carbon is any one of coconut shell carbon, bamboo-based carbon, or corn cob carbon.

9. The method for preparing a high-entropy electrode material to improve the cycling performance of a supercapacitor according to claim 3, characterized in that: The modified CoNiMnFeMgLDH material undergoes post-treatment, which involves adding sodium sulfide to deionized water, ultrasonicating at 30-40W for 15-20 minutes, adding the modified CoNiMnFeMgLDH material, stirring until homogeneous, and reacting at 120-130℃ for 3-4 hours. After the reaction is complete, the mixture is cooled to room temperature, filtered, and dried.

10. The method for preparing a high-entropy electrode material to improve the cycling performance of a supercapacitor according to claim 9, characterized in that: The mass ratio of sodium sulfide, modified CoNiMnFeMgLDH material, and deionized water is (1~3):(5~8):(20~25).

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