Preparation method of transition metal oxide / sulfide electrode material and supercapacitor

Abstract

The invention discloses a preparation method of a transition metal oxide / sulfide electrode material and a supercapacitor, and belongs to the technical field of supercapacitors, and the preparation method comprises the following steps: preparing a metal organic framework material ZIF-67; the preparation method comprises the following steps: carrying out hydrothermal reaction on a metal organic framework material ZIF-67 and a sulfur source to obtain a black solution, filtering precipitates obtained by suction filtration of the black solution onto a microporous membrane, cleaning and drying to obtain Co3S4 / CoS; and placing the Co3S4 / CoS in a muffle furnace for heat treatment to obtain the transition metal oxide / sulfide electrode material. The transition metal oxide / sulfide electrode material Co3S4 / CoS is obtained based on ZIF-67 as a precursor, the specific capacitance of the transition metal oxide / sulfide electrode material Co3S4 / CoS under 1A g reaches 217.45 F g, the specific capacitance of the transition metal oxide / sulfide electrode material Co3S4 / CoS is higher than that of a transition metal oxide / sulfide electrode material obtained by using thioacetamide as a sulfur source and carrying out hydrothermal reaction for 48 h at 120 DEG C, the capacity retention rate reaches 88.69% after 2000 cycles, and the transition metal oxide / sulfide electrode material Co3S4 / CoS shows good cycle stability.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of supercapacitors, and more particularly relates to a preparation method of a transition metal oxide / sulfide electrode material and a supercapacitor. BACKGROUND

[0002] Supercapacitors belong to an advanced energy storage technology, which has a very good application prospect. Supercapacitors and batteries both belong to electrochemical energy storage devices, and their common function is to store and release electrical energy through an external circuit, and are widely used in new energy power peak shaving, portable electronic device power supply, electric vehicle power systems and other fields. The difference is that supercapacitors are physical energy storage, have low energy density, extremely high power density, super-long cycle life, charge and discharge speed of seconds to minutes, linear voltage drop, wide temperature adaptability, high safety, high unit energy cost but long service life, and materials are easier to recycle. Batteries are chemical energy storage, have high energy density, low power density, limited cycle life, charge and discharge speed of hours, slow voltage drop, narrow temperature adaptability, and low safety. Supercapacitors are composed of four parts: separators, electrode materials, current collectors and electrolytes.

[0003] There are some problems with current supercapacitors, such as poor cycle performance, low energy storage efficiency and significant self-consumption. To improve the performance of supercapacitors, one of the important ways is to improve their electrode materials, because this will directly affect the electrochemical properties of the entire device. ZIF-67 belongs to cobalt-based metal-organic framework materials, which has an open grid structure, and has a large surface area, forming a hollow porous structure, enhancing the exposure of active sites, thereby having better chemical stability, good electrochemical properties and flexibility, making it show great potential in various application scenarios. The energy storage mechanism of Co3S4 / CoS is mainly based on pseudo-capacitance, which stores charges through the oxidation and reduction reactions of Co 2+ / Co 3+ and S 2- , and its theoretical specific capacity is much higher than that of traditional double-layer carbon materials (such as activated carbon). Traditional supercapacitors are limited by the double-layer mechanism and have low energy density. Co3S4 / CoS improves the energy density to a level close to that of lithium-ion batteries through pseudo-capacitance reactions, but there is still a gap. SUMMARY

[0004] An object of the present application is to solve at least the above problems and / or disadvantages and to provide at least the advantages described later.

[0005] To achieve these objects and other advantages and in accordance with the purpose of the application, a preparation method of a transition metal oxide / sulfide electrode material is provided, comprising the following steps: Step one, using 2-methyl imidazole and cobalt source to prepare metal organic framework material ZIF-67; Step two, using metal organic framework material ZIF-67 and sulfur source to obtain black solution through hydrothermal reaction, filtering the precipitate in the black solution to microporous membrane through suction filtration, cleaning multiple times, drying to obtain Co3S4 / CoS; Step three, placing Co3S4 / CoS in a muffle furnace to obtain transition metal oxide / sulfide electrode material after heat treatment.

[0006] Preferably, in the step one, the specific method of using 2-methyl imidazole and cobalt source to prepare metal organic framework material ZIF-67 includes: dissolving 2-methyl imidazole in methanol to obtain a clear transparent solution A; dissolving cobalt source in methanol to obtain solution B, after stirring for more than 2h, mixing solution A and solution B, standing at 25℃ for 12h~36h, after filtering, washing and drying at 60℃~90℃, metal organic framework material ZIF-67 is obtained.

[0007] Preferably, the cobalt source is cobalt nitrate hexahydrate; The use amount ratio of 2-methyl imidazole to methanol is 0.03mol~0.05mol:100mL~300mL; the use amount ratio of cobalt nitrate hexahydrate to methanol is 0.01mol:100mL~300mL.

[0008] Preferably, the specific method of step two includes: adding metal organic framework material ZIF-67 and sulfur source into ethanol, and ultrasonic for 10min~20min until it is fully dispersed to obtain a solution; placing the solution in a high-pressure reaction kettle, and reacting at 120℃~160℃ for 12h~48h to obtain a black solution; Filtering the precipitate in the black solution to microporous filter membrane through suction filtration, and cleaning multiple times with anhydrous ethanol; placing the microporous filter membrane into a vacuum drying oven, setting the temperature to 70℃~90℃, and drying for 12h~36h to obtain Co3S4 / CoS.

[0009] Preferably, the sulfur source is thioacetamide or thiourea.

[0010] Preferably, the use amount ratio of ethanol, metal organic framework material ZIF-67 and sulfur source is 5mL~7mL:10mg~13mg:19mg~20mg.

[0011] Preferably, in the step three, the heat treatment temperature is 400℃~500℃, the temperature rising rate is 2℃ / min~4℃ / min, and the holding time is 1h~3h.

[0012] Preferably, in the step two, before the hydrothermal reaction of the metal organic framework material ZIF-67 and the sulfur source, 5wt%-25wt% of TiO2-coated NiO powder based on the mass of the metal organic framework material ZIF-67 is added to the reaction system; the preparation method of the TiO2-coated NiO powder comprises the following steps: S21, after mixing the nickel nitrate solution and the urea, the mixture is added to a high-pressure reaction kettle, and hydrothermal reaction is carried out at 110°C-140°C for 6h-12h, the precipitate is filtered out, and the precipitate is calcined at 300°C-400°C in an air atmosphere for 1h-4h to obtain NiO; S22, the NiO is dispersed in anhydrous ethanol to obtain a NiO suspension, a reaction container containing the NiO suspension is placed in a constant-temperature water bath, the temperature is set to 30°C-40°C, and stirring is started; tetrabutyl titanate is mixed with an equal molar amount of acetylacetone, and stirring is carried out for 20min-40min to obtain a mixed solution; then the mixed solution is diluted with anhydrous ethanol to obtain liquid A; deionized water, anhydrous ethanol and a catalyst are mixed to obtain liquid B; under continuous stirring, equal volumes of liquid A and liquid B are added dropwise to the NiO suspension at a constant speed; after the dropwise addition is completed, stirring is continued at a constant temperature for 4h-12h; the stirring is stopped, and aging is carried out for 12h-24h; the product is separated by a centrifuge, and the washed product is dried in a vacuum drying box at 60°C-80°C for 6h-12h to obtain amorphous TiO2-coated NiO precursor powder; S23, the amorphous TiO2-coated NiO precursor powder is placed in a muffle furnace, and the temperature is raised to 400°C-600°C at a rate of 1°C / min-5°C / min, and calcination is carried out for 2h-4h, and after cooling, the TiO2-coated NiO powder is obtained by grinding.

[0013] Preferably, in the S21, the molar ratio of the nickel nitrate to the urea is 1:3-5, and the concentration of the nickel nitrate solution is 0.01M-0.2M; In the S22, the amount ratio of the NiO to the anhydrous ethanol is 1g-10g:100mL-400mL; The mass ratio of the NiO to the tetrabutyl titanate is 1-10:20:100; In the liquid B, the catalyst is 0.2M nitric acid, and the amount ratio of the deionized water, the anhydrous ethanol and the catalyst is 10mL-20mL:5mL-10mL:1mL-2mL.

[0014] A supercapacitor, wherein the transition metal oxide / sulfide electrode material is prepared by the above-mentioned preparation method of the transition metal oxide / sulfide electrode material.

[0015] The present application at least includes the following beneficial effects: the present application obtains transition metal oxide / sulfide electrode material Co3S4 / CoS based on ZIF-67 as a precursor, and results show that the performance of the transition metal oxide / sulfide electrode material obtained by selecting thiocyanic acid as a sulfur source and hydrothermal reaction at 160 DEG C for 24 hours is optimal, the specific capacitance is as high as 217.45 F g⁻¹ at 1 A g⁻¹, which is 1 times higher than that of the transition metal oxide / sulfide electrode material obtained by using thioacetamide as a sulfur source and hydrothermal reaction at 120 DEG C for 48 hours, the capacity retention rate is 88.69% after 2000 cycles, and good cycle stability is shown; The present application uses the transition metal oxide / sulfide electrode material Co3S4 / CoS obtained by hydrothermal reaction at 160 DEG C for 24 hours as a positive electrode material to construct an asymmetric supercapacitor with activated carbon YP50. The Co3S4 / CoS / / AC has an energy density of 4.0 Wh kg⁻¹ at a power density of 700 W kg⁻¹, and can still maintain an energy density of 2.3 Wh kg⁻¹ at a high power density of 7000 W kg⁻¹. The capacity retention rate of the device is as high as 116.09% after 2000 cycles at a scan rate of 100 mV s⁻¹, and excellent cycle performance is shown. The present application prepares Co3S4 / CoS material by using ZIF-67 as a template, which not only increases the contact area of the material and electrolyte, but also provides a fast channel for ion diffusion, increases the energy storage capacity; this pseudo-capacitive mechanism can store more energy than the physical adsorption of traditional double-layer capacitors, and the energy density can approach the level of batteries; the atomic radius of sulfur atoms is large, which can reduce the volume expansion during the cycle process, and the stable crystal structure can maintain a high capacity after thousands of charge and discharge.

[0016] The application also incorporates TiO2-coated NiO powder into Co3S4 / CoS, and results show that the incorporation of TiO2-coated NiO powder further improves the capacity retention rate and specific capacitance of the transition metal oxide / sulfide electrode material; after the coating of NiO with a TiO2 layer (especially well-crystallized TiO2 after calcination), NiO has high mechanical strength, the TiO2 layer acts as a buffer layer and a constraint layer, effectively inhibiting the volume expansion of the NiO core, preventing particle rupture and pulverization, the surface of NiO directly contacts the electrolyte, and an unstable SEI film is formed in the initial stage of the cycle, in the subsequent volume change process, the SEI film will continuously break and repair, continuously consuming the electrolyte and active lithium ions, resulting in increased impedance and irreversible capacity decay, TiO2 has excellent chemical stability and a wide electrochemical window, and the shell formed by TiO2 can form a more stable and denser SEI film. This stable interface prevents the direct side reaction of NiO with the electrolyte, reduces the loss of active materials and the increase of impedance, and in long-term cycling, the TiO2 shell can physically block the dissolution of NiO and limit it within the shell. At the same time, it also prevents NiO nanoparticles from re-agglomerating into large particles during cycling, avoiding the reduction of reaction area and the decrease of electrode material capacity. Pure NiO has poor electrical conductivity, and in repeated charge and discharge cycles, the severe volume change will cause the active material to pulverize and fall off, making its actual specific capacitance much lower than the theoretical value, but the TiO2 coating layer can prevent the agglomeration of NiO nanoparticles during preparation and cycling, allowing more NiO surface atoms to be exposed and effectively participating in the Faraday reaction, thereby improving the utilization rate of NiO; the uniform TiO2 layer provides a good penetration channel for electrolyte ions and an interface for reaction with the NiO core; compared to pure NiO which is prone to agglomeration, this structure has a more regular and shorter ion diffusion path, allowing ions to reach active sites more quickly, thereby improving the rate performance and effective capacity of the final TiO2-NiO Co3S4 / CoS composite material. In the final TiO2-NiO-doped Co3S4 / CoS composite material, the TiO2 coating layer can provide a more efficient ion migration interface for Co3S4 / CoS, the TiO2 coating layer and the Co3S4 / CoS matrix form a heterostructure, which optimizes the interface charge distribution and enhances the electronic conductivity; during the hydrothermal process, NiO acts as a substrate, the TiO2 coating layer cooperates with ZIF-67 to regulate the nucleation and growth of Co3S4 / CoS, forming a more uniform TiO2-NiO-doped Co3S4 / CoS composite material, and NiO itself has a pseudo-capacitive property, which cooperates with the active sites of the Co3S4 / CoS sulfide to increase the specific capacitance of the transition metal oxide / sulfide electrode material.

[0017] Additional advantages, objects, and features of the application will be apparent from the following description, taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 XRD pattern of metal organic framework material ZIF-67 prepared for Example 1; Figure 2 XRD pattern of Co3S4 / CoS prepared for Example 1; Figure 3 SEM image of metal organic framework material ZIF-67 prepared for Example 1; Figure 4 SEM image of 120℃-48h-TAA prepared for Example 1; Figure 5 SEM image of 120℃-48h-TU prepared for Example 2; Figure 6 SEM image of 160℃-24h-TU prepared for Example 3; Figure 7 CV plots of 120℃-48h-TAA prepared for Example 1, 120℃-12h-TAA prepared for Example 4, 120℃-24h-TAA prepared for Example 5 at 10 mV s -1 Figure 8 GCD plots of 120℃-48h-TAA prepared for Example 1, 120℃-12h-TAA prepared for Example 4, 120℃-24h-TAA prepared for Example 5 at scan density 1 Ag -1 Figure 9 EIS plots of 120℃-48h-TAA prepared for Example 1, 120℃-12h-TAA prepared for Example 4, 120℃-24h-TAA prepared for Example 5; Figure 10 CV plots of 120℃-48h-TU prepared for Example 2, 120℃-12h-TU prepared for Example 6, 120℃-24h-TU prepared for Example 7 at 10 mV s -1 Figure 11 GCD plots of 120℃-48h-TU prepared for Example 2, 120℃-12h-TU prepared for Example 6, 120℃-24h-TU prepared for Example 7 at scan density 1 Ag -1 Figure 12 ​​​​EIS plots of 120 °C-48h-TU prepared for Example 2, 120 °C-12h-TU prepared for Example 6, 120 °C-24h-TU prepared for Example 7; Figure 13 CV plots of 120 °C-48h-TU prepared for Example 2 at 10 mV s -1 ~100 mV s -1 scan rate; Figure 14 GCD plots of 120 °C-48h-TU prepared for Example 2 at 1 A g -1 ~10 A g -1 current density; Figure 15 Rate dependence of specific capacitance and current density of 120 °C-48h-TU prepared for Example 2; Figure 16 CV plots of 160 °C-24h-TU prepared for Example 3 at 10 mV s -1 ~100 mV s -1 scan rate; Figure 17 GCD plots of 160 °C-24h-TU prepared for Example 3 at 1 A g -1 ~10 A g -1 current density; Figure 18 Rate dependence of specific capacitance and current density of 160 °C-24h-TU prepared for Example 3; Figure 19 Capacity retention change of 160 °C-24h-TU prepared for Example 3; Figure 20 GCD plots of activated carbon YP50 at 1 A g -1 Figure 21 CV plots of 160 °C-24h-TU prepared for Example 3 and activated carbon YP50 at 10 mV s -1 Figure 22 GCD plots of Co3S4 / CoS / / AC constructed by 160 °C-24h-TU prepared for Example 3 and activated carbon YP50 at different voltages; Figure 23 CV plots of Co3S4 / CoS / / AC constructed by 160 °C-24h-TU prepared for Example 3 and activated carbon YP50 at different scan rates; Figure 24 GCD plots of Co3S4 / CoS / / AC constructed by 160 °C-24h-TU prepared for Example 3 and activated carbon YP50 at different current densities;​​ Figure 25 The specific capacitance vs. current density rate of Co3S4 / CoS / / AC prepared with 160℃-24h-TU and activated carbon YP50 for Example 3; Figure 26 The energy density vs. specific power of Co3S4 / CoS / / AC prepared with 160℃-24h-TU and activated carbon YP50 for Example 3; Figure 27 The impedance plot of Co3S4 / CoS / / AC prepared with 160℃-24h-TU and activated carbon YP50 for Example 3; Figure 28 The capacity retention plot of Co3S4 / CoS / / AC prepared with 160℃-24h-TU and activated carbon YP50 for Example 3 at 100mVs -1 DETAILED DESCRIPTION

[0019] The application will be further described in conjunction with the drawings, so that those skilled in the art can implement the application according to the description and the drawings.

[0020] It should be understood that the terms such as "have", "contain" and "include" used herein do not exclude the presence or addition of one or more other elements or combinations thereof. Example 1 A preparation method of a transition metal oxide / sulfide electrode material, comprising the following steps: Step one, 3.284g 2-methylimidazole is dissolved in 200mL methanol to obtain a clear transparent solution A. 2.9102g of cobalt nitrate hexahydrate is dissolved in the same volume of methanol to obtain solution B, after stirring for more than 2h, solution A and solution B are mixed, and the mixture is placed at 25℃ for 24h, and then filtered, washed and dried at 80℃ to obtain a metal organic framework material ZIF-67; Step two, 60mL of ethanol is measured and placed in a beaker, 120mg of the metal organic framework material ZIF-67 and 195mg of thioacetamide (TAA) are added to the beaker and ultrasonically dispersed for 15min to obtain a ZIF / TAA solution; the ZIF / TAA solution is placed in a high-pressure reaction kettle, and a black solution is obtained after reaction at 120℃ for 48h. The precipitate in the black solution is filtered onto a microporous filter membrane by suction filtration, and the microporous filter membrane is placed in a vacuum drying oven, set at a temperature of 80℃, and dried for 24h to obtain Co3S4 / CoS; Step three, the transition metal oxide / sulfide electrode material is obtained by heat treatment of Co3S4 / CoS in a muffle furnace, and is denoted as 120℃-48h-TAA. ​

[0021] Example 2 A preparation method of a transition metal oxide / sulfide electrode material, comprising the following steps: Step one, 3.284g 2-methylimidazole is dissolved in 200mL methanol to obtain a clear transparent solution A. 2.9102g of cobalt nitrate hexahydrate is dissolved in the same volume of methanol to obtain solution B, after stirring for more than 2h, solution A and solution B are mixed, and the mixture is placed at 25℃ for 24h, and then filtered, washed and dried at 80℃ to obtain a metal organic framework material ZIF-67; Step two, 60mL of ethanol is measured into a beaker, 120mg of the metal organic framework material ZIF-67 and 198mg of thiourea (TU) are added into the beaker and ultrasonically dispersed for 15min to obtain a ZIF / TU solution; the ZIF / TU solution is placed in a high-pressure reaction kettle, and a black solution is obtained after reaction at 120℃ for 48h. The precipitate in the black solution is filtered onto a microporous filter membrane by suction filtration, and the microporous filter membrane is cleaned with anhydrous ethanol by suction filtration for several times. The microporous filter membrane is placed in a vacuum drying oven, and the temperature is set to 80℃, and the drying time is 24h to obtain Co3S4 / CoS; Step three, the Co3S4 / CoS is placed in a muffle furnace for heat treatment to obtain a transition metal oxide / sulfide electrode material, which is recorded as 120℃-48h-TU.

[0022] Example 3 A preparation method of a transition metal oxide / sulfide electrode material, comprising the following steps: Step one, 3.284g 2-methylimidazole is dissolved in 200mL methanol to obtain a clear transparent solution A. 2.9102g of cobalt nitrate hexahydrate is dissolved in the same volume of methanol to obtain solution B, after stirring for more than 2h, solution A and solution B are mixed, and the mixture is placed at 25℃ for 24h, and then filtered, washed and dried at 80℃ to obtain a metal organic framework material ZIF-67; Step two, 60mL of ethanol is measured into a beaker, 120mg of the metal organic framework material ZIF-67 and 198mg of thiourea (TU) are added into the beaker and ultrasonically dispersed for 15min to obtain a ZIF / TU solution; the ZIF / TU solution is placed in a high-pressure reaction kettle, and a black solution is obtained after reaction at 160℃ for 24h. The precipitate in the black solution is filtered onto a microporous filter membrane by suction filtration, and the microporous filter membrane is cleaned with anhydrous ethanol by suction filtration for several times. The microporous filter membrane is placed in a vacuum drying oven, and the temperature is set to 80℃, and the drying time is 24h to obtain Co3S4 / CoS; Step three, the Co3S4 / CoS is placed in a muffle furnace for heat treatment to obtain a transition metal oxide / sulfide electrode material, which is recorded as 160℃-24h-TU.

[0023] Example 4 A method for preparing a transition metal oxide / sulfide electrode material, comprising the following steps: Step one, 3.284g 2-methylimidazole is dissolved in 200mL methanol to obtain a clear transparent solution A. 2.9102g of cobalt nitrate hexahydrate is dissolved in the same volume of methanol to obtain solution B, after stirring for more than 2h, solution A and solution B are mixed, and the mixture is placed at 25℃ for 24h, and then filtered, washed and dried at 80℃ to obtain a metal organic framework material ZIF-67; Step two, 60mL of ethanol is measured into a beaker, 120mg of metal organic framework material ZIF-67 and 195mg of thioacetamide (TAA) are added into the beaker and ultrasonically dispersed for 15min to obtain a ZIF / TAA solution; the ZIF / TAA solution is placed in a high-pressure reaction kettle and reacted at 120℃ for 12h to obtain a black solution. The precipitate in the black solution is filtered onto a microporous filter membrane by suction filtration and cleaned with anhydrous ethanol for several times. The microporous filter membrane is placed in a vacuum drying oven, the temperature is set to 80℃, and the drying time is 24h to obtain Co3S4 / CoS; Step three, the Co3S4 / CoS is heat treated in a muffle furnace to obtain a transition metal oxide / sulfide electrode material, which is recorded as 120℃-12h-TAA.

[0024] Example 5 A method for preparing a transition metal oxide / sulfide electrode material, comprising the following steps: Step one, 3.284g 2-methylimidazole is dissolved in 200mL methanol to obtain a clear transparent solution A. 2.9102g of cobalt nitrate hexahydrate is dissolved in the same volume of methanol to obtain solution B, after stirring for more than 2h, solution A and solution B are mixed, and the mixture is placed at 25℃ for 24h, and then filtered, washed and dried at 80℃ to obtain a metal organic framework material ZIF-67; Step two, 60mL of ethanol is measured into a beaker, 120mg of metal organic framework material ZIF-67 and 195mg of thioacetamide (TAA) are added into the beaker and ultrasonically dispersed for 15min to obtain a ZIF / TAA solution; the ZIF / TAA solution is placed in a high-pressure reaction kettle and reacted at 120℃ for 24h to obtain a black solution. The precipitate in the black solution is filtered onto a microporous filter membrane by suction filtration and cleaned with anhydrous ethanol for several times. The microporous filter membrane is placed in a vacuum drying oven, the temperature is set to 80℃, and the drying time is 24h to obtain Co3S4 / CoS; Step three, the Co3S4 / CoS is heat treated in a muffle furnace to obtain a transition metal oxide / sulfide electrode material, which is recorded as 120℃-24h-TAA.

[0025] Example 6 A preparation method of a transition metal oxide / sulfide electrode material, comprising the following steps: Step one, 3.284g 2-methylimidazole is dissolved in 200mL methanol to obtain a clear transparent solution A. 2.9102g of cobalt nitrate hexahydrate is dissolved in the same volume of methanol to obtain solution B, after stirring for more than 2h, solution A and solution B are mixed, and the mixture is placed at 25℃ for 24h, and then filtered, washed and dried at 80℃ to obtain a metal organic framework material ZIF-67; Step two, 60mL of ethanol is measured into a beaker, 120mg of the metal organic framework material ZIF-67 and 198mg of thiourea (TU) are added into the beaker and ultrasonically dispersed for 15min to obtain a ZIF / TU solution; the ZIF / TU solution is placed in a high-pressure reaction kettle and reacted at 120℃ for 12h to obtain a black solution. The precipitate in the black solution is filtered onto a microporous filter membrane by suction filtration and cleaned with anhydrous ethanol for several times. The microporous filter membrane is placed in a vacuum drying oven, the temperature is set to 80℃, and the drying time is 24h to obtain Co3S4 / CoS; Step three, the Co3S4 / CoS is heat-treated in a muffle furnace to obtain a transition metal oxide / sulfide electrode material, which is recorded as 120℃-12h-TU.

[0026] Example 7 A preparation method of a transition metal oxide / sulfide electrode material, comprising the following steps: Step one, 3.284g 2-methylimidazole is dissolved in 200mL methanol to obtain a clear transparent solution A. 2.9102g of cobalt nitrate hexahydrate is dissolved in the same volume of methanol to obtain solution B, after stirring for more than 2h, solution A and solution B are mixed, and the mixture is placed at 25℃ for 24h, and then filtered, washed and dried at 80℃ to obtain a metal organic framework material ZIF-67; Step two, 60mL of ethanol is measured into a beaker, 120mg of the metal organic framework material ZIF-67 and 198mg of thiourea (TU) are added into the beaker and ultrasonically dispersed for 15min to obtain a ZIF / TU solution; the ZIF / TU solution is placed in a high-pressure reaction kettle and reacted at 120℃ for 12h to obtain a black solution. The precipitate in the black solution is filtered onto a microporous filter membrane by suction filtration and cleaned with anhydrous ethanol for several times. The microporous filter membrane is placed in a vacuum drying oven, the temperature is set to 80℃, and the drying time is 24h to obtain Co3S4 / CoS; Step three, the Co3S4 / CoS is heat-treated in a muffle furnace to obtain a transition metal oxide / sulfide electrode material, which is recorded as 120℃-12h-TU.

[0027] Example 8 A preparation method of a transition metal oxide / sulfide electrode material, comprising the following steps: Step one, 3.284g 2-methylimidazole was dissolved in 200mL methanol to obtain a clear transparent solution A. 2.9102g of cobalt nitrate hexahydrate was dissolved in the same volume of methanol to obtain solution B, after stirring for more than 2h, solution A and solution B were mixed, and the mixture was placed at 25°C for 24h, after filtration, washing and drying at 80°C, metal organic framework material ZIF-67 was obtained; Step two, 60mL of ethanol was measured into a beaker, 120mg of metal organic framework material ZIF-67, 198mg of thiourea (TU) and 30mg of TiO2-coated NiO powder were added into the beaker, and ultrasonic was applied for 15min until they were fully dispersed to obtain a ZIF / TU / TiO2-NiO solution; the ZIF / TU / TiO2-NiO solution was placed in a high-pressure reaction kettle, and reacted at 160°C for 24h. The precipitate in the solution after reaction was filtered onto a microporous filter membrane by suction filtration, and the microporous filter membrane was placed in a vacuum drying oven, and the temperature was set to 80°C, and the drying time was 24h to obtain Co3S4 / CoS doped with TiO2-NiO; The preparation method of the TiO2-coated NiO powder comprises: S21, a 0.2M nickel nitrate solution was mixed with urea and then added into a high-pressure reaction kettle, and the molar ratio of nickel nitrate to urea was 1:4, hydrothermal reaction was carried out at 120°C for 6h, the precipitate was filtered out, and the precipitate was calcined at 350°C for 3h in an air atmosphere to obtain NiO; S22, 10g of NiO was dispersed in 400mL of anhydrous ethanol to obtain a NiO suspension, a three-necked flask containing the NiO suspension was placed in a constant-temperature water bath, the temperature was set to 40°C, and stirring was started at a speed of 200rpm; 85g of tetrabutyl titanate (0.25mol) was mixed with 0.25mol of acetylacetone, and stirring was carried out at 200rpm for 30min to obtain a mixed solution; then the mixed solution was diluted with 80mL of anhydrous ethanol to a constant volume of 200mL to obtain solution A; 140mL of deionized water, 50mL of anhydrous ethanol and 10mL of 0.2M concentrated nitric acid were mixed to a constant volume of 200mL to obtain solution B; under continuous stirring, 200mL of solution A and 200mL of solution B were added dropwise into the NiO suspension at a rate of 2mL / min; after the dropwise addition was completed, the stirring reaction was continued at 40°C for 6h; the stirring was stopped, and the product was aged for 24h; the product was separated by a centrifuge, and the washed product was dried in a vacuum drying oven at 80°C for 12h to obtain an amorphous TiO2-coated NiO precursor powder; S23, the amorphous TiO2-coated NiO precursor powder was heated in a muffle furnace at a rate of 5°C / min to 450°C, and calcined for 3h, and then ground after cooling to obtain TiO2-coated NiO powder; Step three, the transition metal oxide / sulfide electrode material is obtained by heat treatment of the Co3S4 / CoS doped with TiO2-NiO in a muffle furnace.

[0028] Example 9 A preparation method of a transition metal oxide / sulfide electrode material, comprising the following steps: Step one, 3.284g of 2-methylimidazole is dissolved in 200mL of methanol to obtain a clear transparent solution A. 2.9102g of cobalt nitrate hexahydrate is dissolved in the same volume of methanol to obtain solution B. After stirring for more than 2h, solution A and solution B are mixed, and the mixture is left to stand at 25℃ for 24h. After filtration, washing and drying at 80℃, a metal organic framework material ZIF-67 is obtained. Step two, 60mL of ethanol is measured and placed in a beaker, 120mg of the metal organic framework material ZIF-67, 198mg of thiourea (TU) and 6mg of TiO2-coated NiO powder are added to the beaker, and ultrasonic treatment is performed for 15min until they are fully dispersed to obtain a ZIF / TU / TiO2-NiO solution. The ZIF / TU / TiO2-NiO solution is placed in a high-pressure reaction kettle and reacted at 160℃ for 24h. The precipitate in the solution after reaction is filtered onto a microporous filter membrane by suction filtration, and the microporous filter membrane is placed in a vacuum drying oven and set to a temperature of 80℃ for 24h of drying time to obtain Co3S4 / CoS doped with TiO2-NiO. The preparation method of the TiO2-coated NiO powder is the same as that of Example 8.

[0029] Step three, the transition metal oxide / sulfide electrode material is obtained by heat treatment of the Co3S4 / CoS doped with TiO2-NiO in a muffle furnace.

[0030] Comparative Example 1 A preparation method of a transition metal oxide / sulfide electrode material, comprising the following steps: Step one, 3.284g of 2-methylimidazole is dissolved in 200mL of methanol to obtain a clear transparent solution A. 2.9102g of cobalt nitrate hexahydrate is dissolved in the same volume of methanol to obtain solution B. After stirring for more than 2h, solution A and solution B are mixed, and the mixture is left to stand at 25℃ for 24h. After filtration, washing and drying at 80℃, a metal organic framework material ZIF-67 is obtained. Step two, 60 mL of ethanol was measured into a beaker, 120 mg of metal organic framework material ZIF-67, 198 mg of thiourea (TU) and 30 mg of TiO2 powder were added into the beaker, and ultrasonic was applied for 15 min until they were fully dispersed to obtain a ZIF / TU / TiO2 solution; the ZIF / TU / TiO2 solution was placed in a high-pressure reaction kettle, and reacted at 160℃ for 24 h. The precipitate in the solution after reaction was filtered onto a microporous filter membrane by suction filtration and cleaned with anhydrous ethanol for several times. The microporous filter membrane was placed in a vacuum drying oven, and the temperature was set to 80℃, and the drying time was 24 h to obtain Co3S4 / CoS doped with TiO2; Step three, the Co3S4 / CoS doped with TiO2 was placed in a muffle furnace for heat treatment to obtain a transition metal oxide / sulfide electrode material.

[0031] Comparative example 2 A preparation method of a transition metal oxide / sulfide electrode material, comprising the following steps: Step one, 3.284 g of 2-methylimidazole was dissolved in 200 mL of methanol to obtain a clear transparent solution A. 2.9102 g of cobalt nitrate hexahydrate was dissolved in the same volume of methanol to obtain solution B, and after stirring for more than 2 h, solution A and solution B were mixed, and then placed at 25℃ for 24 h. After filtration, washing and drying at 80℃, metal organic framework material ZIF-67 was obtained; Step two, 60 mL of ethanol was measured into a beaker, 120 mg of metal organic framework material ZIF-67, 198 mg of thiourea (TU) and 30 mg of NiO powder were added into the beaker, and ultrasonic was applied for 15 min until they were fully dispersed to obtain a ZIF / TU / NiO solution; the ZIF / TU / NiO solution was placed in a high-pressure reaction kettle, and reacted at 160℃ for 24 h. The precipitate in the solution after reaction was filtered onto a microporous filter membrane by suction filtration and cleaned with anhydrous ethanol for several times. The microporous filter membrane was placed in a vacuum drying oven, and the temperature was set to 80℃, and the drying time was 24 h to obtain Co3S4 / CoS doped with NiO; Step three, the Co3S4 / CoS doped with NiO was placed in a muffle furnace for heat treatment to obtain a transition metal oxide / sulfide electrode material.

[0032] Comparative example 3 A preparation method of a transition metal oxide / sulfide electrode material, comprising the following steps: Step one, 3.284 g of 2-methylimidazole was dissolved in 200 mL of methanol to obtain a clear transparent solution A. 2.9102 g of cobalt nitrate hexahydrate was dissolved in the same volume of methanol to obtain solution B, and after stirring for more than 2 h, solution A and solution B were mixed, and then placed at 25℃ for 24 h. After filtration, washing and drying at 80℃, metal organic framework material ZIF-67 was obtained; Step two, 60 mL of ethanol was measured into a beaker, 120 mg of metal organic framework material ZIF-67, 198 mg of thiourea (TU) and 20 mg of TiO2 powder and 10 mg of NiO powder were added into the beaker, and ultrasonic was applied for 15 min until they were fully dispersed to obtain a ZIF / TU / TiO2 / NiO solution; the ZIF / TU / TiO2 / NiO solution was placed in a high-pressure reaction kettle, and reacted at 160°C for 24 h. The precipitate in the solution after reaction was filtered onto a microporous filter membrane by suction filtration, and the microporous filter membrane was placed in a vacuum drying oven, and the temperature was set to 80°C, and the drying time was 24 h to obtain Co3S4 / CoS doped with TiO2 and NiO; Step three, the Co3S4 / CoS doped with TiO2 and NiO was placed in a muffle furnace for heat treatment to obtain a transition metal oxide / sulfide electrode material.

[0033] The transition metal oxide / sulfide electrode material obtained in the above examples and comparative examples was prepared as a positive electrode, and the specific method included: First, the active material was mixed with acetylene black and polyvinylidene fluoride at a mass ratio of 8:1:1, and was placed in a mortar. Second, after being fully ground and mixed, 2 mL of N-methyl-2-pyrrolidone was added, and the mixture was ground to obtain an electrode slurry. A small brush was used to dip the prepared slurry and uniformly coat it on a foam nickel with an area of 2 cm 2 Then, the foam nickel coated with the electrode slurry was placed in a vacuum oven and dried at 80°C overnight to obtain a positive electrode.

[0034] Figure 1 The diffraction peaks formed by the metal organic framework material ZIF-67 prepared in Example 1 were shown, and the results were almost consistent with the standard diffraction peak positions in the range of 5° to 40°, proving that the precursor was successfully synthesized. Figure 2 The XRD pattern of the Co3S4 / CoS micrometer cube prepared in Example 1 was shown. In Figure 2 we can clearly see sharp diffraction signals, which are basically consistent with the standard cards of the signals of Co3S4 (PDF #74-0138) and CoS (PDF #75-0605), proving that the target product was successfully synthesized. The strong diffraction peaks at 2θ=31.5°, 38.2°, 41.8°, 50.3°, 55.2° and 58.8° correspond to the (311), (400), (331), (511), (440) and (442) crystal faces of Co3S4, while the strong diffraction peaks at 2θ=30.5°, 35.2°, 46.9°, 54.2°, 63.5° and 66.1° correspond to the (100), (101), (102), (110), (200) and (112) crystal faces of CoS, and two broad peaks appear in the middle, indicating the coexistence of multiple phases, which is a two-phase composite system containing Co3+ and Co 2+ Two valence states.

[0035] The morphology of the electrode material was obtained by SEM characterization. The SEM image of the metal-organic framework material ZIF-67 at a scale of 5 μm is shown below. Figure 3 As shown, it exhibits a rhombic dodecahedral configuration, with good crystal homogeneity and complete crystal faces.

[0036] Next, SEM images of the three sets of Co3S4 / CoS from Examples 1-3 were tested, as shown below. Figure 4 , Figure 5 , Figure 6 As shown. Among them. Figure 4 The Co3S4 / CoS obtained by hydrothermal reaction at 120℃ for 48 hours with TAA as the sulfur source has poor crystal uniformity and severe agglomeration. Figure 5 The Co3S4 / CoS obtained using TU as the sulfur source at 120℃ for 48 hours of hydrothermal reaction showed more regular and dispersed crystals with a size less than 2 μm compared to those obtained using TAA as the sulfur source. Figure 6 The Co3S4 / CoS obtained by hydrothermal reaction at 160℃ for 24 hours with TU as the sulfur source exhibits a rhombic polyhedron shape, complete crystallinity, and the most dispersed volume compared to the previous two groups, thus possessing the best electrochemical performance.

[0037] For Examples 1, 4, and 5, the electrochemical performance of Co3S4 / CoS sulfides prepared at different hydrothermal times (12h, 24h, and 48h) using TAA as the sulfur source at 120℃ was tested in a three-electrode system (using a Shanghai Zhenhua CHI660D electrochemical workstation). Figure 7 The three groups of materials have a voltage range of 0V to 0.6V and a voltage of 10mV s. -1 The cyclic voltammograms below show two pairs of clear redox reaction peaks on each CV curve. During this process, the integral area of ​​the image varies greatly, with the 48h group having the largest area, indicating strong charge storage capacity and high electrode capacity. Figure 8 To scan at a density of 1A g -1 The GCD curves were obtained below, and during this process, the specific capacitances of the three materials were 102.73 Fg. -1 171.64F g -1 207.01F g -1 This indicates that, under the same conditions, the active material with a hydrothermal reaction time of 48 h has a higher specific capacitance than other reaction times. Figure 9The semicircular diameter in the high-frequency region of the impedance curve of the three groups of materials represents the resistance value of charge transfer, and the slope of the straight line in the low-frequency region is directly related to the size of the diffusion resistance. The impedance observed for 48 h shows that the high-frequency region has a larger slope, and the electrical diffusion impedance is smaller, indicating that the efficiency of charge transfer is higher. This situation can be understood as follows: under a certain dosage, by increasing the time consumed by the reaction, the precursor ZIF-67 and TAA can fully react, thereby forming a more complete Co3S4 / CoS crystal structure and improving the chemical properties of the material surface.

[0038] The change of the sulfur source also affects the performance of the final product. Under the same hydrothermal reaction temperature, the electrochemical performance of thiourea (TU) at 12 h, 24 h and 48 h (Examples 2, 6 and 7) was investigated, and the test was still carried out in a three-electrode system, as shown in Figure 10 The cyclic voltammograms of the three groups of materials in the range of 0V~0.6V at 10mV s -1 ~100mV s -1 are the same as when TAA is used as the sulfur source, and there are two pairs of redox peaks. The integral area of 24 h is calculated to be greater than that of 48 h, which may be due to the incomplete sulfidation, resulting in too much precursor residue and causing a false "high" appearance. Figure 11 The GCD curves of the three groups of active materials at a scan density of 1A g -1 ~2A g -1 ~3A g -1 The specific capacitance of the three groups of materials is 172.18F g -1 , 206.73F g -1 , and 207.10F g -1 , respectively. Compared with TAA as the sulfur source, the specific capacitance of TU as the sulfur source is slightly better, which may be related to the difference in decomposition kinetics and chemical activity of TU. The release rate of TU is more stable than that of TAA, which is conducive to the uniform coordination of sulfur atoms and cobalt ions in ZIF-67, and slightly increases the conductivity of the active material, thereby producing a weak positive effect. Figure 12 The impedance curves of the three groups of materials are shown in Figure 8. The 48 h group has the largest slope in the high-frequency region, the smallest diffusion impedance, and the best charge transfer efficiency. In summary, the electrochemical performance is best when the hydrothermal reaction conditions are 120℃ and TU is used as the sulfur source, which is attributed to the fact that 48 h of sufficient sulfidation makes the Co3S4 / CoS crystal more complete and reduces surface defects.

[0039] Figure 13 The voltammogram of 120℃-48h-TU prepared in Example 2 in the range of 0V~0.6V at 10mVs -1 ~100mVs -1 is shown in Figure 9. Figure 14 The GCD of the hydrothermal reaction 120℃-48h-TU at different current densities is shown in Figure 10. At 1A g -1 , 2A g-1 ,3A g -1 5A g -1 10A g -1 The specific capacitances at the following values ​​are 207.10 F g. -1 98.55F g -1 63.27F g -1 35.64Fg -1 15.82F g -1 .like Figure 15 As shown, the specific capacitance decreases with increasing current density, reflecting a weakening ability to maintain capacitance at high rates.

[0040] Electrochemical data of the 160℃-24h-TU prepared in Example 3 are as follows: Figure 16 , Figure 17 , Figure 18 As shown, Figure 16 For 160℃-24h-TU within the range of 0V~0.6V, 10mV s -1 ~100mV s -1 The following is a diagram of Fu'an. Figure 17 The GCD of 160℃-24h-TU at different current densities is shown. During this process, at 1A g... -1 2 A g -1 ,3A g -1 5A g -1 10A g -1 The specific capacitances at the following values ​​are 217.45 F g. -1 102.91F g -1 65.45 F g -1 36.73F g -1 ,16F g -1 like Figure 18 As shown.

[0041] The 160℃-24h-TU prepared in Example 3 was used at 100mV s -1 A 2000-cycle charge-discharge test was conducted at a scan rate, and the retention rate change was recorded every 100 cycles. The results are as follows: Figure 19 As shown, in the initial stage, the specific capacitance gradually increases as the active material slowly comes into full contact with the electrolyte. When the number of cycles increases, the capacitance retention rate at 160℃-24h-TU is 88.69%.

[0042] The 160℃-24h-TU prepared in Example 3 was selected as the positive electrode material and YP50 activated carbon was selected as the negative electrode material to construct an asymmetric supercapacitor with a two-electrode system. Its performance characteristics were comprehensively examined by implementing cyclic voltammetry, constant current charge-discharge experiments and AC impedance tests. Figure 20The GCD curve of Co3S4 / CoS / / AC, the specific capacitance of AC was calculated to be 77.9 F g -1 at 1 A g -1 . Figure 21 The CV curve of Co3S4 / CoS / / AC. The two-electrode system was constructed for electrochemical performance test, and the best voltage window was determined to be 1.4 V by constant current charge and discharge test, as shown in Figure 22 , and the cyclic voltammetry and constant current charge and discharge test were carried out based on this.

[0043] The cyclic voltammograms of different scan rates under the best voltage window of 1.4 V are shown in Figure 23 . The redox peaks can be clearly seen due to the redox reaction, which proves that this asymmetric supercapacitor is dominated by pseudo-capacitance behavior. And Figure 24 shows the constant current charge and discharge test under various current density settings. The five curves are roughly symmetrical, and the specific capacitance change is plotted as shown in Figure 25 , and the specific capacitances under five current densities are 14.71 F g -1 , 12.14 F g -1 , 10.93 F g -1 , 10.36 F g -1 , and 8.57 F g -1 . The relationship between the energy density and specific power of Co3S4 / CoS / / AC is shown in Figure 26 . At the power densities of 700 W kg -1 , 1400 W kg -1 , 2100 W kg -1 , 3500 W kg -1 , and 7000 W kg -1 , the energy densities are 4.0 Wh kg -1 , 3.3 Wh kg -1 , 2.9 Wh kg -1 , 2.8 Wh kg -1 , and 2.3 Wh kg -1 . Figure 27 The AC impedance curve of Co3S4 / CoS / / AC is shown. The slope in the high frequency region is large, so the resistance is small, and the impedance level is good. Figure 28 The capacity retention of the asymmetric supercapacitor and the change of the CV curve before and after cycling are shown after 2000 cycles at a scan rate of 100 mV s -1 . After 2000 cycles, the capacity retention rate of the asymmetric supercapacitor is 116.09%, which shows that the assembled asymmetric supercapacitor has good cycle stability.

[0044] The capacity retention (2000 cycles) and specific capacitance (1A g -1 ) of the transition metal oxide / sulfide electrode materials obtained from Example 3, Example 8, Example 9, Comparative Example 1, Comparative Example 2 and Comparative Example 3 were compared, and the following table was obtained. Table 1 Comparison of capacity retention and specific capacitance of each sample As can be seen from Table 1, the transition metal oxide / sulfide electrode material prepared by incorporating the TiO2-coated NiO powder has higher capacity retention and specific capacitance, and exhibits more excellent electrochemical performance. When applied to the positive electrode material of a supercapacitor, the electrical performance of the supercapacitor can be significantly improved.

[0045] The number of devices and the scale of processing described herein are intended to be illustrative of the application. Applications, modifications and variations of the application will be apparent to those skilled in the art without departing from the general concept of the application.

[0046] Although embodiments of the application have been disclosed in connection with the specified embodiments, it should be understood that they are not intended to limit the scope of the application to the particular configurations and arrangements described. Accordingly, there are many other variations of the application, which are covered by the application and are within the scope of the claims.

Claims

1. A method for preparing a transition metal oxide / sulfide electrode material, characterized in that, Includes the following steps: Step 1: Prepare metal-organic framework material ZIF-67 using 2-methylimidazole and a cobalt source; Step 2: A black solution is obtained by hydrothermal reaction of metal-organic framework material ZIF-67 and sulfur source. The precipitate from the black solution is filtered onto a microporous membrane, washed multiple times, and dried to obtain Co3S4 / CoS. Step 3: Heat-treat Co3S4 / CoS in a muffle furnace to obtain transition metal oxide / sulfide electrode material.

2. The method for preparing the transition metal oxide / sulfide electrode material as described in claim 1, characterized in that, In step one, the specific method for preparing the metal-organic framework material ZIF-67 using 2-methylimidazole and a cobalt source includes: dissolving 2-methylimidazole in methanol to obtain a clear and transparent solution A; dissolving the cobalt source in methanol to obtain solution B; stirring for more than 2 hours; mixing solution A and solution B; allowing the mixture to stand at 25°C for 12 to 36 hours; and then filtering, washing, and drying at 60°C to 90°C to obtain the metal-organic framework material ZIF-67.

3. The method for preparing the transition metal oxide / sulfide electrode material as described in claim 2, characterized in that, The cobalt source is cobalt nitrate hexahydrate; The ratio of 2-methylimidazole to methanol is 0.03 mol to 0.05 mol: 100 mL to 300 mL; the ratio of cobalt nitrate hexahydrate to methanol is 0.01 mol: 100 mL to 300 mL.

4. The method for preparing the transition metal oxide / sulfide electrode material as described in claim 1, characterized in that, The specific method of step two includes: adding metal-organic framework material ZIF-67 and sulfur source to ethanol, sonicating for 10 min to 20 min until they are fully dispersed to obtain a solution; placing the solution in a high-pressure reactor and reacting at 120℃ to 160℃ for 12 h to 48 h to obtain a black solution; The precipitate in the black solution was filtered onto a microporous membrane by vacuum filtration and washed multiple times with anhydrous ethanol. The microporous membrane was then placed in a vacuum drying oven at a temperature of 70℃~90℃ for 12h~36h to obtain Co3S4 / CoS.

5. The method for preparing the transition metal oxide / sulfide electrode material as described in claim 4, characterized in that, The sulfur source is thioacetamide or thiourea.

6. The method for preparing the transition metal oxide / sulfide electrode material as described in claim 4, characterized in that, The ratio of ethanol, metal-organic framework material ZIF-67, and sulfur source is 5 mL~7 mL: 10 mg~13 mg: 19 mg~20 mg.

7. The method for preparing the transition metal oxide / sulfide electrode material as described in claim 1, characterized in that, In step three, the heat treatment temperature is 400℃~500℃, the heating rate is 2℃ / min~4℃ / min, and the holding time is 1h~3h.

8. The method for preparing the transition metal oxide / sulfide electrode material as described in claim 1, characterized in that, In step two, before the hydrothermal reaction of the metal-organic framework material ZIF-67 and the sulfur source, 5wt%~25wt% of TiO2-coated NiO powder, accounting for 5wt%~25wt% of the mass of the metal-organic framework material ZIF-67, is added to the reaction system; the preparation method of the TiO2-coated NiO powder includes: S21. Mix nickel nitrate solution and urea and add them to a high-pressure reactor. React hydrothermally at 110℃~140℃ for 6h~12h. Filter out the precipitate and calcine the precipitate in air at 300℃~400℃ for 1h~4h to obtain NiO. S22. NiO is dispersed in anhydrous ethanol to obtain a NiO suspension. The reaction vessel containing the NiO suspension is placed in a constant temperature water bath, and the temperature is set to 30°C~40°C. Stirring is started. Tetrabutyl titanate is mixed with an equimolar amount of acetylacetone and stirred for 20min~40min to obtain a mixed solution. The mixed solution is then diluted with anhydrous ethanol to obtain solution A. Deionized water, anhydrous ethanol and catalyst are mixed to obtain solution B. Under continuous stirring, equal volumes of solution A and solution B are added dropwise to the NiO suspension at a constant rate. After the addition is complete, the reaction is stirred at a constant temperature for 4h~12h. Stirring is stopped and the mixture is allowed to stand for 12h~24h. The product is separated by centrifugation. The washed product is dried in a vacuum drying oven at 60°C~80°C for 6h~12h to obtain amorphous TiO2-coated NiO precursor powder. S23. Place the amorphous TiO2-coated NiO precursor powder in a muffle furnace, heat it to 400°C~600°C at a rate of 1°C / min~5°C / min, calcine for 2h~4h, cool and grind to obtain TiO2-coated NiO powder.

9. The method for preparing the transition metal oxide / sulfide electrode material as described in claim 8, characterized in that, In S21, the molar ratio of nickel nitrate to urea is 1:3~5, and the concentration of the nickel nitrate solution is 0.01M~0.2M; In S22, the ratio of NiO to anhydrous ethanol is 1g~10g:100mL~400mL; The mass ratio of NiO to tetrabutyl titanate is 1~10:20:100; In solution B, the catalyst is 0.2M nitric acid, and the ratio of deionized water, anhydrous ethanol and catalyst is 10mL~20mL:5mL~10mL:1mL~2mL.

10. A supercapacitor, characterized in that, The positive electrode of the supercapacitor is prepared from a transition metal oxide / sulfide electrode material, which is prepared by the method for preparing the transition metal oxide / sulfide electrode material according to any one of claims 1-9.

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