High-performance electrochemical energy storage composite material and preparation method and application thereof

Abstract

The application belongs to the technical field of novel energy storage materials, and particularly relates to a high-performance electrochemical energy storage composite material and a preparation method and application thereof. The preparation method comprises the following steps: adding spherical copper powder into a chemical plating solution to prepare copper-coated nickel powder; mixing the copper-coated nickel powder, lanthanum selenium oxide powder and calcium chloride powder, and obtaining a composite foam metal substrate after cold pressing, sintering and boiling water immersion; adding onion carbon into a nitric acid solution for ultrasonic dispersion, then adding a silane coupling agent for microwave reaction, and obtaining modified onion carbon after filtration and drying; adding the modified onion carbon, cobalt nitrate and iron nitrate into water and uniformly mixing, adjusting the pH to 9-11, placing the composite foam metal substrate into the solution, and obtaining the electrochemical energy storage composite material after heating reaction and treatment. The electrochemical energy storage composite material prepared by the application has stable structure, excellent corrosion resistance and oxidation resistance, can be directly used as a working electrode of a supercapacitor, and can effectively improve the specific capacity and cycle stability of the supercapacitor.

Description

Technical Field

[0001] This invention belongs to the field of novel energy storage materials technology, specifically relating to a high-performance electrochemical energy storage composite material, its preparation method, and its application. Background Technology

[0002] Developing renewable and clean energy sources such as solar and wind power is crucial. However, clean energy power generation is intermittent and unstable, necessitating energy storage technologies to improve power quality and grid connection stability. Therefore, developing efficient energy storage technologies is an important guarantee for the sustainable use of clean energy.

[0003] Among various energy storage technologies for new clean energy sources, supercapacitors are widely used in energy storage devices under complex operating conditions due to their advantages such as strong cycle stability, mature technology, inexpensive raw materials, wide operating temperature range, and low maintenance costs. However, with the continuous improvement of clean energy harvesting technologies, the performance requirements for supercapacitors are also increasing, necessitating higher energy density and longer, more stable cycle performance. Foamed metals possess a three-dimensional porous structure, and their high porosity provides an extremely high specific surface area, significantly improving ion transport efficiency. They can also support more electrode active materials, making them excellent for capacitor fabrication. Copper is a commonly used material for preparing foamed metals, exhibiting high conductivity, but its poor corrosion resistance and susceptibility to oxidation are extremely unfavorable for its use as a positive electrode material for long-term cycling.

[0004] Therefore, it is urgent to optimize the design of foam metal materials and improve the preparation process to construct a new type of supercapacitor with both high energy density and long cycle life, thereby promoting the breakthrough development of electrochemical energy storage technology. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the first objective of this invention is to provide a method for preparing high-performance electrochemical energy storage composite materials.

[0006] The second objective of this invention is to provide a high-performance electrochemical energy storage composite material obtained by the above preparation method, which has a high specific surface area, stable structure, and excellent corrosion resistance and oxidation resistance.

[0007] The third objective of this invention is to provide an application of a high-performance electrochemical energy storage composite material in supercapacitors. This composite material can be directly used as the working electrode of a supercapacitor, effectively improving the specific capacitance and cycle stability of the supercapacitor.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A method for preparing a high-performance electrochemical energy storage composite material, comprising the following steps:

[0010] (1) Add spherical copper powder to the chemical plating solution, stir ultrasonically for 20-40 min under heating conditions, filter and wash to obtain nickel-coated copper powder;

[0011] (2) The nickel-coated copper powder, lanthanum oxide powder and calcium chloride powder are mixed evenly, cold-pressed for 1-3 minutes, and then pre-sintered and sintered in a hydrogen atmosphere. After cooling, they are immersed in boiling water to obtain a composite foam metal substrate.

[0012] (3) Add onion carbon to nitric acid solution and disperse it by ultrasonication. Then add silane coupling agent and carry out microwave reaction. After filtration and drying, the modified onion carbon is obtained.

[0013] (4) The modified onion carbon, cobalt nitrate and ferric nitrate are added to water and mixed evenly. The pH is adjusted to 9-11 using sodium hydroxide to obtain a mixed solution. The composite foam metal substrate is placed in the mixed solution, heated to react, filtered, washed and dried to obtain the high-performance electrochemical energy storage composite material.

[0014] Further, the particle size of the spherical copper powder in step (1) is 15-25 μm; the ratio of the amount of spherical copper powder to the chemical plating solution is 15-30 g: 1 L; the composition and concentration of the chemical plating solution are: nickel chloride 0.1-0.2 mol / L, sodium hypophosphite 0.15-0.3 mol / L, sodium citrate 0.05-0.2 mol / L, and sodium acetate 0.12-0.18 mol / L.

[0015] Furthermore, the heating temperature in step (1) is 60-80℃; the coating thickness of the nickel-coated copper powder is 1-6μm.

[0016] Furthermore, the lanthanum oxide powder of selenium mentioned in step (2) is prepared by the following process:

[0017] Lanthanum and selenium were ball-milled and mixed in ethanol, dried, calcined in an inert gas atmosphere, cooled, and ground to obtain the lanthanum oxide powder.

[0018] Further, the mass ratio of lanthanum, selenium and ethanol is 1:(0.8-0.9):(0.1-0.3); the calcination temperature is 1000-1100℃ and the time is 12-18h; the particle size of the lanthanum oxide selenium powder is 0.5-2μm.

[0019] Further, in step (2), the particle size of the calcium chloride powder is 5-10 μm; the volume ratio of the nickel-coated copper powder, lanthanum selenide oxide powder and calcium chloride powder is 1:(0.1-0.15):(7-9); the pressure of the cold pressing is 150-250 MPa; the temperature of the pre-sintering is 600-700℃ and the time is 1-2 h; the temperature of the re-sintering is 900-1000℃ and the time is 2-4 h.

[0020] Further, the pH value of the nitric acid solution in step (3) is 4-5; the silane coupling agent is 3-(methacryloyloxy)propyltrimethoxysilane; the mass ratio of the onion carbon, silane coupling agent and nitric acid solution is 1:(0.1-0.2):(20-40); the temperature of the microwave reaction is 70-100℃ and the time is 2-4h.

[0021] Further, in step (4), the mass ratio of the modified onion carbon, cobalt nitrate, iron nitrate and composite foam metal substrate is 1:(0.5-1.2):(0.3-0.8):(1.3-1.6); the heating reaction temperature is 70-100℃ and the time is 4-7h.

[0022] A high-performance electrochemical energy storage composite material is prepared by the above-described method for preparing high-performance electrochemical energy storage composite materials.

[0023] The application of the aforementioned high-performance electrochemical energy storage composite materials in supercapacitors.

[0024] The beneficial technical effects of this invention are as follows:

[0025] 1. This invention involves sintering core-shell structured nickel-coated copper powder and adding lanthanum selenide oxide as a reinforcing phase to prepare a composite foam metal that can serve as a capacitor substrate, exhibiting excellent structural and cycling stability. Specifically, depositing a nickel layer on the copper powder surface to form a core-shell structure significantly improves the oxidation and corrosion resistance of copper, effectively mitigating volume changes during charge and discharge, thereby enhancing the material's cycling stability. Lanthanum selenide oxide itself possesses good conductivity and cycling stability. Without affecting the material's conductivity, lanthanum selenide oxide powder and large-sized nickel-coated copper powder form a size mismatch, thus refining the grain size. Moreover, selenides and nickel form a strong interfacial bond, improving the strength and hardness of the foam metal, which helps the capacitor achieve long-term stable cycling. Simultaneously, the rare-earth properties of lanthanum can refine the nickel plating layer grain size, reduce porosity, and combine with selenium to form a dense passivation film, further enhancing the foam metal's corrosion resistance.

[0026] 2. This invention combines CoFe-LDH with modified onion carbon on a composite foam metal substrate to improve the specific capacitance of capacitor electrodes. Onion carbon possesses an sp² hybrid carbon layer structure, allowing electrons to move freely within the layers, thus exhibiting good conductivity. Furthermore, its spherical multilayer structure endows it with a large specific surface area, demonstrating excellent charge storage capacity. Simultaneously, onion carbon also exhibits good chemical and mechanical stability. The combination of LDH and onion carbon enables the material to possess both the high power density of double-layer capacitance and the high energy density of Faraday capacitance, effectively optimizing the charge storage mechanism. In addition, the rigid structure of onion carbon can buffer the volume changes of LDH during charge and discharge, thereby improving the structural stability and cycle life of the composite material. This invention also subjectes the onion carbon to acid oxidation treatment and modification using a coupling agent. After acid oxidation treatment, the surface defects of the onion carbon increase, resulting in better binding with the groups in the coupling agent and the formation of more active sites. This not only optimizes the bonding interface between onion carbon and LDH, reducing interfacial resistance and further enhancing the charge storage capacity of the material, but also improves the strength and stability of the onion carbon itself. Attached Figure Description

[0027] Figure 1 This is a scanning electron microscope image of the high-performance electrochemical energy storage composite material prepared in Example 1. Detailed Implementation

[0028] The following is a further detailed description of the present invention in conjunction with specific preferred embodiments, and it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention. Specific conditions not specified in the embodiments are performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, all reagents or instruments used are conventional products obtained through commercial channels.

[0029] (I) Implementation Examples Example 1

[0030] Example 1 provides a method for preparing a high-performance electrochemical energy storage composite material, the specific steps of which are as follows:

[0031] (1) Nickel chloride, sodium hypophosphite, sodium citrate and sodium acetate were dissolved in deionized water to prepare a chemical plating solution, wherein the concentrations of nickel chloride, sodium hypophosphite, sodium citrate and sodium acetate were 0.15 mol / L, 0.2 mol / L, 0.15 mol / L and 0.16 mol / L respectively; according to the ratio of 20 g to 1 L of spherical copper powder to chemical plating solution, spherical copper powder with a particle size of 15-25 μm was added to the chemical plating solution, and then the mixture was ultrasonically stirred at 70 °C for 30 min; after the reaction was completed, the solid material was filtered out, and after washing, nickel-coated copper powder with a coating thickness of 1-6 μm was obtained.

[0032] (2) Lanthanum, selenium and ethanol were mixed and ball-milled in a mass ratio of 1:0.8:0.2. After drying at room temperature, the mixture was placed in a tube furnace and calcined at 1000℃ for 16 hours under an argon atmosphere. After natural cooling and grinding, lanthanum selenium oxide powder with a particle size of 0.5-2μm was obtained. The nickel-coated copper powder, lanthanum selenium oxide powder and calcium chloride powder with a particle size of 5-10μm obtained in step (1) were mixed evenly in a volume ratio of 1:0.12:8 and cold-pressed at 200MPa for 2 minutes to obtain a metal substrate. The metal substrate was transferred to a hydrogen atmosphere and pre-sintered at 650℃ for 1 hour, and then sintered at 900℃ for 3 hours. After cooling the product, it was soaked in boiling water to remove calcium chloride and obtain a composite foam metal substrate.

[0033] (3) According to the mass ratio of onion carbon, 3-(methacryloyloxy)propyltrimethoxysilane and nitric acid solution 1:0.15:30, onion carbon was added to nitric acid solution with pH 4 and ultrasonically dispersed for 15 min. Then 3-(methacryloyloxy)propyltrimethoxysilane was added and microwaved at 80℃ for 3 h. After filtration and drying, modified onion carbon was obtained.

[0034] (4) According to the mass ratio of modified onion carbon, cobalt nitrate, ferric nitrate, composite foam metal substrate and deionized water of 1:1:0.5:1.4:30, the modified onion carbon, cobalt nitrate and ferric nitrate were added to deionized water and ultrasonically dispersed evenly. The pH was adjusted to 10 with 0.08 mol / L sodium hydroxide solution to obtain a mixed solution. The composite foam metal substrate was placed in the mixed solution and then reacted at 80℃ for 6 h. After filtration and drying, the above high-performance electrochemical energy storage composite material was obtained.

[0035] Example 1 also provides a high-performance electrochemical energy storage composite material, which is prepared by the above preparation method.

[0036] The scanning electron microscope image of the high-performance electrochemical energy storage composite material prepared in this embodiment is shown below. Figure 1 As shown. Example 2

[0037] Example 2 provides a method for preparing a high-performance electrochemical energy storage composite material, the specific steps of which are as follows:

[0038] (1) Nickel chloride, sodium hypophosphite, sodium citrate and sodium acetate were dissolved in deionized water to prepare a chemical plating solution, wherein the concentrations of nickel chloride, sodium hypophosphite, sodium citrate and sodium acetate were 0.1 mol / L, 0.15 mol / L, 0.05 mol / L and 0.12 mol / L respectively; according to the ratio of 15 g to 1 L of spherical copper powder to chemical plating solution, spherical copper powder with a particle size of 15-25 μm was added to the chemical plating solution, and then the mixture was ultrasonically stirred at 60 °C for 20 min; after the reaction was completed, the solid material was filtered out, and after washing, nickel-coated copper powder with a coating thickness of 1-6 μm was obtained.

[0039] (2) Lanthanum, selenium and ethanol were mixed and ball-milled in a mass ratio of 1:0.8:0.1. After drying at room temperature, the mixture was placed in a tube furnace and calcined at 1000℃ for 12 hours under an argon atmosphere. After natural cooling and grinding, lanthanum selenium oxide powder with a particle size of 0.5-2μm was obtained. The nickel-coated copper powder, lanthanum selenium oxide powder and calcium chloride powder with a particle size of 5-10μm obtained in step (1) were mixed evenly in a volume ratio of 1:0.1:9 and cold-pressed at 150MPa for 1 minute to obtain a metal substrate. The metal substrate was transferred to a hydrogen atmosphere and pre-sintered at 600℃ for 1 hour, and then sintered at 900℃ for 2 hours. After cooling the product, it was soaked in boiling water to remove calcium chloride and obtain a composite foam metal substrate.

[0040] (3) According to the mass ratio of onion carbon, 3-(methacryloyloxy)propyltrimethoxysilane and nitric acid solution 1:0.1:20, onion carbon was added to nitric acid solution with pH 4 and ultrasonically dispersed for 10 min. Then 3-(methacryloyloxy)propyltrimethoxysilane was added and microwaved at 70 °C for 2 h. After filtration and drying, modified onion carbon was obtained.

[0041] (4) According to the mass ratio of modified onion carbon, cobalt nitrate, ferric nitrate, composite foam metal substrate and deionized water 1:0.5:0.3:1.3:20, the modified onion carbon, cobalt nitrate and ferric nitrate were added to deionized water and ultrasonically dispersed evenly. The pH was adjusted to 9 with 0.05mol / L sodium hydroxide solution to obtain a mixed solution. The composite foam metal substrate was placed in the mixed solution and then reacted at 70℃ for 4h. After filtration and drying, the above high-performance electrochemical energy storage composite material was obtained.

[0042] Example 2 also provides a high-performance electrochemical energy storage composite material, which is prepared by the above preparation method. Example 3

[0043] Example 3 provides a method for preparing a high-performance electrochemical energy storage composite material, the specific steps of which are as follows:

[0044] (1) Nickel chloride, sodium hypophosphite, sodium citrate and sodium acetate were dissolved in deionized water to prepare a chemical plating solution, wherein the concentrations of nickel chloride, sodium hypophosphite, sodium citrate and sodium acetate were 0.2 mol / L, 0.3 mol / L, 0.2 mol / L and 0.18 mol / L respectively; according to the ratio of 30 g to 1 L of spherical copper powder to chemical plating solution, spherical copper powder with a particle size of 15-25 μm was added to the chemical plating solution, and then the mixture was ultrasonically stirred at 80 °C for 40 min; after the reaction was completed, the solid material was filtered out, and after washing, nickel-coated copper powder with a coating thickness of 1-6 μm was obtained.

[0045] (2) Lanthanum, selenium and ethanol were mixed and ball-milled in a mass ratio of 1:0.9:0.3. After drying at room temperature, the mixture was placed in a tube furnace and calcined at 1100℃ for 18h under an argon atmosphere. After natural cooling and grinding, lanthanum selenium oxide powder with a particle size of 0.5-2μm was obtained. The nickel-coated copper powder, lanthanum selenium oxide powder and calcium chloride powder with a particle size of 5-10μm obtained in step (1) were mixed evenly in a volume ratio of 1:0.15:7 and cold-pressed at 250MPa for 3min to obtain a metal substrate. The metal substrate was transferred to a hydrogen atmosphere and pre-sintered at 700℃ for 2h, and then sintered at 1000℃ for 4h. After cooling the product, it was soaked in boiling water to remove calcium chloride and obtain a composite foam metal substrate.

[0046] (3) Onion carbon, 3-(methacryloyloxy)propyltrimethoxysilane and nitric acid solution were mixed in a mass ratio of 1:0.2:40. Onion carbon was added to nitric acid solution with pH 5 and ultrasonically dispersed for 20 min. Then 3-(methacryloyloxy)propyltrimethoxysilane was added and microwaved at 100 °C for 4 h. After filtration and drying, modified onion carbon was obtained.

[0047] (4) According to the mass ratio of modified onion carbon, cobalt nitrate, ferric nitrate, composite foam metal substrate and deionized water of 1:1.2:0.8:1.6:50, the modified onion carbon, cobalt nitrate and ferric nitrate were added to deionized water and ultrasonically dispersed evenly. Then, the pH was adjusted to 11 with 0.1mol / L sodium hydroxide solution to obtain a mixed solution. The composite foam metal substrate was placed in the mixed solution and reacted at 100℃ for 7h. After filtration and drying, the above high-performance electrochemical energy storage composite material was obtained.

[0048] Example 3 also provides a high-performance electrochemical energy storage composite material, which is prepared by the above preparation method.

[0049] (ii) Comparative Example

[0050] Comparative Example 1

[0051] Comparative Example 1 is basically the same as Example 1, except that steps (1) and (2) are different. Steps (1) and (2) of Comparative Example 1 are as follows:

[0052] (1) Dissolve nickel chloride, sodium hypophosphite, sodium citrate and sodium acetate in deionized water to prepare a chemical plating solution, wherein the concentrations of nickel chloride, sodium hypophosphite, sodium citrate and sodium acetate are 0.15 mol / L, 0.2 mol / L, 0.15 mol / L and 0.16 mol / L respectively;

[0053] (2) Lanthanum, selenium, and ethanol were added to a ball mill at a mass ratio of 1:0.8:0.2 and mixed and ball-milled. After drying at room temperature, the mixture was placed in a tube furnace and calcined at 1000℃ for 16 hours under an argon atmosphere. After natural cooling and grinding, lanthanum selenium oxide powder with a particle size of 0.5-2 μm was obtained. Spherical copper powder with a particle size of 15-25 μm, lanthanum selenium oxide powder, and calcium chloride powder with a particle size of 5-10 μm were mixed evenly at a volume ratio of 1:0.12:8 and cold-pressed at 200 MPa for 2 minutes to obtain... Metal substrate; the metal substrate was transferred to a hydrogen atmosphere and pre-sintered at 650°C for 1 h, and then sintered at 900°C for 3 h. After cooling the product, it was soaked in boiling water to remove calcium chloride and obtain a foam metal substrate; according to the ratio of foam metal substrate to chemical plating solution of 20 g: 1 L, the foam metal substrate was placed in the chemical plating solution of step (1), and then ultrasonically stirred at 70°C for 30 min; after the reaction was completed, the solid material was filtered out and washed to obtain a composite foam metal substrate.

[0054] Comparative Example 2

[0055] Comparative Example 2 is basically the same as Example 1, except that: the lanthanum oxide selenium in step (2) is omitted, and the amounts of nickel-coated copper powder and calcium chloride are the same as in Example 1.

[0056] Comparative Example 3

[0057] Comparative Example 3 is basically the same as Example 1, except that lanthanum selenide oxide in step (2) is replaced with lanthanum oxide.

[0058] Comparative Example 4

[0059] Comparative Example 4 is basically the same as Example 1, except that: cobalt nitrate and iron nitrate in step (4) are omitted, and the amount of modified onion carbon and composite foam metal substrate is the same as in Example 1.

[0060] (III) Application Examples

[0061] The composite materials obtained in Examples 1-3 and Comparative Examples 1-4 were used as positive electrode sheets to prepare supercapacitors. The specific fabrication process is as follows:

[0062] Electrolyte: 1 mol / L sodium sulfate solution;

[0063] Positive electrode: The high-performance electrochemical energy storage composite materials obtained in Examples 1-3 and Comparative Examples 1-4 were cut into (2cm×1cm) pieces.

[0064] Negative electrode: Graphite, acetylene black, and PVDF (polyvinylidene fluoride) binder are mixed in a mass ratio of 7:2:1 and ground clockwise. Then NMP (N-methylpyrrolidone) is added and the mixture is ground clockwise under a baking lamp until it reaches a suspended but not solidified state. The mixture is then coated onto nickel foam (2cm×1cm) and dried to obtain the negative electrode.

[0065] Assemble the supercapacitor in the order of positive electrode, glass fiber diaphragm, and negative electrode, wherein the size of the glass fiber diaphragm is (2cm × 1.5cm).

[0066] (iv) Test Cases

[0067] 1. Tensile strength test: The physical tensile properties of the electrochemical energy storage composite materials of Examples 1-3 and Comparative Examples 1-4 were tested according to the national standard GB / T 228.1-2021 "Metallic materials - Tensile test at room temperature". The results are shown in Table 1.

[0068] 2. Corrosion resistance test: According to the national standard GB / T 39534-2020 "Determination of uniform corrosion rate of stainless steel and nickel-based alloys in corrosive liquids", the corrosion resistance of the electrochemical energy storage composite materials of Examples 1-3 and Comparative Examples 1-4 in solution was tested, and the results are shown in Table 1.

[0069] 3. Electrochemical performance test: Electrochemical tests were conducted using the supercapacitor assembled in the corresponding test case using the Blue Electric test cabinet. The test current was 1A / g, and the results are shown in Table 1.

[0070]

[0071] As shown in Table 1, the high-performance electrochemical energy storage composite materials prepared by Examples 1-3 of the present invention have stable structures, strong corrosion resistance, high specific capacitance and excellent cycle stability when used in supercapacitors.

[0072] Compared to Example 1, Comparative Example 1 replaced nickel-coated copper powder with spherical copper powder, and then placed the resulting foam metal substrate into a chemical plating solution for nickel plating. Comparative Example 2 omitted lanthanum selenide oxide in step (2), Comparative Example 3 replaced lanthanum selenide oxide in step (2) with lanthanum oxide, and Comparative Example 4 omitted cobalt nitrate and ferric nitrate in step (4). The mechanical strength and corrosion resistance of the resulting materials were reduced to varying degrees, and the number of capacitor cycles was also reduced. Specific analysis shows that: on the one hand, the present invention forms a core-shell structure by plating a nickel layer on the surface of copper powder, which can significantly improve the oxidation resistance and corrosion resistance of the material, effectively slow down the volume change during charging and discharging, and thus enhance the cycle stability of the material. The present invention also adds lanthanum selenide oxide as a reinforcing phase in the foam metal. Without affecting the conductivity of the material, lanthanum selenide oxide powder and large-size nickel-coated copper powder will form a size mismatch, thereby refining the grains. Moreover, selenide and nickel will form a strong interfacial bond, improving the strength and hardness of the foam metal, which helps the capacitor achieve long-term stable cycle use. Meanwhile, the rare earth properties of lanthanum can refine the grain size of the nickel plating layer, reduce porosity, and combine with selenium to form a dense passivation film, further improving the corrosion resistance of the foam metal. On the other hand, this invention combines CoFe-LDH with modified onion carbon on a composite foam metal substrate to improve the specific capacitance of the capacitor. Onion carbon has an sp² hybrid carbon layer structure, allowing electrons to move freely within the layers, thus exhibiting good conductivity. Moreover, its spherical multilayer structure gives it a large specific surface area, demonstrating excellent charge storage capacity. Onion carbon also possesses good chemical and mechanical stability. The combination of LDH and onion carbon enables the material to possess both the high power density of double-layer capacitance and the high energy density of Faraday capacitance, effectively optimizing the charge storage mechanism. Furthermore, the rigid structure of onion carbon can buffer the volume change of LDH during charge and discharge, thereby improving the structural stability and cycle life of the composite material. This invention also subjectes the onion carbon to acid oxidation treatment and modification using a coupling agent. After acid oxidation treatment, the surface defects of the onion carbon increase, resulting in better binding with the groups in the coupling agent and the formation of more active sites. This not only optimizes the bonding interface between onion carbon and LDH, reducing the interface resistance and further improving the charge storage capacity of the material, but also improves the strength and stability of onion carbon itself.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. The basic principles and main features of the present invention have been described above with specific implementation schemes. Based on the present invention, some modifications or substitutions can be made, but these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of protection claimed by the present invention.

Claims

1. A method for preparing a high-performance electrochemical energy storage composite material, characterized in that, Includes the following steps: (1) Add spherical copper powder to the chemical plating solution, stir ultrasonically for 20-40 min under heating conditions, filter and wash to obtain nickel-coated copper powder; (2) The nickel-coated copper powder, lanthanum oxide powder and calcium chloride powder are mixed evenly, cold-pressed for 1-3 minutes, and then pre-sintered and re-sintered in a hydrogen atmosphere. After cooling, they are immersed in boiling water to obtain a composite foam metal substrate. (3) Add onion carbon to nitric acid solution and disperse it by ultrasonication. Then add silane coupling agent and carry out microwave reaction. After filtration and drying, the modified onion carbon is obtained. (4) The modified onion carbon, cobalt nitrate and ferric nitrate are added to water and mixed evenly. The pH is adjusted to 9-11 using sodium hydroxide to obtain a mixed solution. The composite foam metal substrate is placed in the mixed solution, heated to react, filtered, washed and dried to obtain the high-performance electrochemical energy storage composite material.

2. The method for preparing the high-performance electrochemical energy storage composite material according to claim 1, characterized in that, The spherical copper powder in step (1) has a particle size of 15-25 μm; the ratio of the spherical copper powder to the chemical plating solution is 15-30 g: 1 L; the composition and concentration of the chemical plating solution are: nickel chloride 0.1-0.2 mol / L, sodium hypophosphite 0.15-0.3 mol / L, sodium citrate 0.05-0.2 mol / L, and sodium acetate 0.12-0.18 mol / L.

3. The method for preparing the high-performance electrochemical energy storage composite material according to claim 1, characterized in that, The heating temperature in step (1) is 60-80℃; the coating thickness of the nickel-coated copper powder is 1-6μm.

4. The method for preparing the high-performance electrochemical energy storage composite material according to claim 1, characterized in that, The lanthanum oxide powder of selenium mentioned in step (2) is prepared by the following process: Lanthanum and selenium were ball-milled and mixed in ethanol, dried, calcined in an inert gas atmosphere, cooled, and ground to obtain the lanthanum oxide powder.

5. The method for preparing the high-performance electrochemical energy storage composite material according to claim 4, characterized in that, The mass ratio of lanthanum, selenium, and ethanol is 1:(0.8-0.9):(0.1-0.3); the calcination temperature is 1000-1100℃ and the time is 12-18h; the particle size of the lanthanum oxide powder is 0.5-2μm.

6. The method for preparing the high-performance electrochemical energy storage composite material according to claim 1, characterized in that, The particle size of the calcium chloride powder in step (2) is 5-10 μm; the volume ratio of the nickel-coated copper powder, lanthanum oxide selenium powder and calcium chloride powder is 1:(0.1-0.15):(7-9); the pressure of the cold pressing is 150-250 MPa; the temperature of the pre-sintering is 600-700℃ and the time is 1-2 h; the temperature of the re-sintering is 900-1000℃ and the time is 2-4 h.

7. The method for preparing the high-performance electrochemical energy storage composite material according to claim 1, characterized in that, The pH value of the nitric acid solution in step (3) is 4-5; the silane coupling agent is 3-(methacryloyloxy)propyltrimethoxysilane; the mass ratio of the onion carbon, silane coupling agent and nitric acid solution is 1:(0.1-0.2):(20-40); the temperature of the microwave reaction is 70-100℃ and the time is 2-4h.

8. The method for preparing the high-performance electrochemical energy storage composite material according to claim 1, characterized in that, In step (4), the mass ratio of modified onion carbon, cobalt nitrate, iron nitrate and composite foam metal substrate is 1:(0.5-1.2):(0.3-0.8):(1.3-1.6); the heating reaction temperature is 70-100℃ and the time is 4-7h.

9. A high-performance electrochemical energy storage composite material, characterized in that, It is prepared by the preparation method of the high-performance electrochemical energy storage composite material according to any one of claims 1-8.

10. The application of the high-performance electrochemical energy storage composite material according to claim 9 in supercapacitors.

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