CN106981370A - Preparation method and method of testing based on phase-change induced layered transition family metal oxide electrode super capacitor - Google Patents

Abstract

The invention discloses a preparation method and a testing method of a layered transition group metal oxide electrode supercapacitor based on phase change induction. In the fabrication process, phase change-induced layered transition metal oxide electrodes were prepared by combining template self-assembly and electrochemical deposition techniques to prepare transition metal oxide conductive frameworks, followed by two consecutive heat treatments to achieve detemplate respectively. and the introduction of oxygen vacancies, the prepared layered transition metal oxide electrodes were symmetrically installed on both sides of the diaphragm to obtain a supercapacitor; during the test, the assembled supercapacitor was directly immersed in 1mol/L Na ₂ SO ₄ solution for Electrochemical testing. The preparation method and testing method of the supercapacitor described in the present invention are simple and easy to operate, and the prepared supercapacitor has the characteristics of high power density, high energy density, good cycle stability and the like.

Description

Fabrication of supercapacitors with layered transition metal oxide electrodes based on phase transition induction preparation method and test method

technical field

The invention belongs to the technical field of energy storage, and relates to the preparation and testing of a supercapacitor, in particular to a preparation method and a testing method of a layered transition group metal oxide electrode supercapacitor based on phase change induction.

Background technique

As the next generation of electrical energy storage devices, supercapacitors have very broad application prospects in fields such as electric vehicles, portable electronic products, and high-power sources. According to different energy storage principles, supercapacitors can be divided into electric double layer supercapacitors and pseudocapacitive supercapacitors.

The energy storage principle of the current commercial electric double layer supercapacitor mainly uses the polarization process of electrolyte ions to store energy instead of redox reaction. The energy density is relatively low (~20μF cm ^-2 ), which limits its further application. Compared with electric double layer supercapacitors, pseudocapacitive supercapacitors (redox reaction) have higher energy density, making them more promising.

Transition group metal oxides are a typical pseudocapacitive material and have attracted widespread attention due to their low price, good stability, and large specific capacity. In order to further increase the energy density of supercapacitors, transition group metal oxides are used as a new electrode materials have been introduced into supercapacitor applications. However, these transition group metal oxides (V ₂ O ₃ , VO ₂ , TiO ₂ , ZnO, RuO, MnO ₂ , MoO ₂ , CuO, NbO ₂ , etc.) have long electron transfer paths and low The excellent cation passability leads to the specific capacity far lower than the theoretical capacity and the power density far lower than that of the electric double layer supercapacitor in the actual research. Although a large number of studies have reported the problems of pseudocapacitive materials, the solution is often to improve their performance in the electrochemical reaction process by combining transition metal oxides with conductive materials. However, there is no essential solution to the problem of low ion passability inside transition metal oxide crystals. Therefore, the performance of composite electrodes formed from transition metal oxides and conductive materials is not ideal, which limits their wide application in high power density, high energy density, and cycle-stable supercapacitors.

Contents of the invention

Aiming at the problems existing in the above-mentioned prior art, the present invention provides a preparation method and a testing method for a layered transition metal oxide electrode supercapacitor based on phase change induction, so as to realize the essential solution to the internal ion passage of transition metal oxide crystals. low problem. In conjunction with the accompanying drawings of the description, the technical solution of the present invention is as follows:

A method for preparing a supercapacitor based on a layered transition group metal oxide electrode induced by a phase change, the method is to symmetrically assemble a layered transition group metal oxide electrode induced by a phase change on both sides of the diaphragm, and the phase change induces The preparation steps of the layered transition metal oxide electrode are as follows:

a. The metal foil substrate is fully cleaned in acid solution, deionized water and ethanol in sequence, and vacuum-dried;

b. Using polystyrene microspheres on the metal foil substrate, a polystyrene film is obtained by heating and evaporating, as a template for further electrochemical deposition;

c. Electrodeposit transition metal oxide precursors on polystyrene films, and remove polystyrene films under reducing atmosphere and high temperature conditions to obtain three-dimensional nanoporous transition metal oxides;

d. Put the three-dimensional nanoporous transition metal oxide into a tube furnace, heat and keep warm to obtain a layered transition metal oxide electrode induced by phase transition.

Further, in the step b, the mass volume percent concentration of polystyrene microspheres is 0.2-20%, the heating and evaporation temperature is 40-95° C., and the thickness of the obtained polystyrene film is 2-30 μm.

Further, the high temperature condition in the step c is a temperature of 100-800° C. and a time of 0-10 h.

Further, the transition group metal oxide is V ₂ O ₃ , VO ₂ , TiO ₂ , ZnO, RuO, MnO ₂ , MoO ₂ , CuO or NbO ₂ , and the annealing conditions are temperature 100-800°C, time 0-10h .

A test method based on a phase change-induced layered transition group metal oxide electrode supercapacitor, said supercapacitor is a layered transition group metal oxide electrode supercapacitor based on a phase change induced by the aforementioned preparation method, said The test method is an electrochemical test method, and the specific test process is: immerse the supercapacitor in a 1mol/L Na ₂ SO ₄ solution, and set the range of the volt-ampere characteristic curve at -0.8V～+0.8V or 0～1.4V Under different scanning rates, change the scan rate to obtain the cyclic voltammetry curve at different scan rates; charge and discharge for a long time at a constant current density to obtain cycle stability data; after the capacitor is fully charged, continue to test the self-discharge performance of the supercapacitor at the open circuit voltage.

Compared with prior art, the beneficial effect of the present invention is:

1. The preparation method of the layered transition group metal oxide electrode supercapacitor based on phase change induction in the present invention is a combination of template self-assembly, electrochemical deposition and heat treatment technology. Fluid surface, and then transition metal oxides are electrodeposited in the gaps of the template, and then the template is removed and the phase transition is induced to generate active materials through two-step heat treatment. The above-mentioned seamless integration technology not only improves the electronic conductivity between the active materials but also minimizes the contact resistance between the active materials and the current collector.

2. In the preparation method of the layered transition metal oxide electrode supercapacitor based on phase change induction of the present invention, the prepared three-dimensional porous nanostructure not only provides a super high specific surface area, but also in the electrolyte, the electrode The material has three-dimensional continuous nanopores, which can effectively reduce the diffusion resistance of ions in the electrolyte, so that the electrolyte can be evenly distributed on the surface of the active material, which is conducive to the full progress of the redox reaction on the surface of the metal oxide.

3. In the preparation method of the layered transition metal oxide electrode supercapacitor based on phase change induction of the present invention, an appropriate concentration of oxygen vacancies is generated inside the transition metal oxide crystal through an appropriate heat treatment process, which can effectively Reducing the diffusion energy of cations inside the crystal is conducive to the occurrence of intercalation-type redox reactions. In summary, the capacitor can effectively utilize active materials.

4. The preparation method of the layered transition group metal oxide electrode supercapacitor based on the phase change induction of the present invention is easy to operate, and the supercapacitor obtained by simple assembly can be directly used for energy storage. The supercapacitor prepared by the method of the present invention Capacitors have excellent cycle stability, high power density, and high energy density.

Description of drawings

Fig. 1 is a schematic flow chart of the preparation method steps of a layered transition metal oxide electrode supercapacitor based on phase transition induction according to the present invention, wherein:

Figure 1a is a schematic diagram of the polystyrene template self-assembled on the surface of the current collector through the thermal evaporation process;

Figure 1b is a schematic diagram of the growth of transition group metal oxide precursors in polystyrene templates by electrodeposition technology;

Figure 1c is a schematic diagram of the three-dimensional porous transition metal oxide obtained by removing the polystyrene template through heat treatment;

Figure 1d is a schematic diagram of the generation of active materials on the surface of three-dimensional porous transition metal oxides through phase transition induced by heat treatment;

Figure 1e is a schematic diagram of a supercapacitor assembled with phase transition-induced layered transition metal oxide electrodes.

Fig. 2 is a scanning electron microscope and pore size analysis characterization diagram of the three-dimensional nanoporous V ₂ O ₃ /VO _2-x layered vanadium oxide prepared by the preparation method of the present invention, wherein:

Figure 2a is the SEM characterization image of the cross-section of the three-dimensional nanoporous V ₂ O ₃ /VO _2-x layered vanadium oxide;

Figure 2b is the front SEM characterization image of the three-dimensional nanoporous V ₂ O ₃ /VO _2-x layered vanadium oxide;

Figure 2c is a TEM characterization image of the three-dimensional nanoporous V ₂ O ₃ /VO _2-x layered vanadium oxide hierarchical aperture;

Figure 2d is the TEM characterization image of the small pores of the three-dimensional nanoporous V ₂ O ₃ /VO _2-x layered vanadium oxide;

Figure 2e is a TEM characterization image of the mesopores of the three-dimensional nanoporous V ₂ O ₃ /VO _2-x layered vanadium oxide;

Figure 2f is the N ₂ adsorption-desorption curve of the three-dimensional nanoporous V ₂ O ₃ /VO _2-x layered vanadium oxide;

Fig. 2g is a diagram of the pore size distribution of the three-dimensional nanoporous V ₂ O ₃ /VO _2-x layered vanadium oxide.

Fig. 3 is the XRD spectra of three-dimensional nanoporous V ₂ O ₃ /VO _2-x layered vanadium oxides prepared under different heat treatment conditions in Examples 1 to 4 of the present invention.

Fig. 4 is a comparison chart of the capacities of V ₂ O ₃ /VO _2-x layered vanadium oxide electrodes under different heat treatment conditions adopted in Examples 1 to 4 of the present invention at different scan rates.

Fig. 5 is the superstructure composed of three-dimensional nanoporous V ₂ O ₃ /VO _2-x layered vanadium oxide, V ₂ O ₃ and VO ₂ electrodes prepared in Example 1, Example 5 and Example 6 of the present invention Electrochemical performance comparison of capacitors;

Figure 5a is a supercapacitor composed of three-dimensional nanoporous V ₂ O ₃ , VO ₂ , V ₂ O ₃ /VO _2-x layered vanadium oxide electrodes in Example 1 of the present invention at a scan rate of 50mV s ^-1 Comparison of cyclic voltammetry curves;

Figure 5b is a comparison of the specific capacity of supercapacitors composed of three-dimensional nanoporous V ₂ O ₃ , VO ₂ , V ₂ O ₃ /VO _2-x (A) layered vanadium oxide electrodes at different scan rates.

Fig. 6 is the HRTEM and HAADF-STEM characterization of each part of the three-dimensional nanoporous V ₂ O ₃ /VO _2-x layered vanadium oxide prepared in Example 1 of the present invention;

Figure 6a is a high-resolution transmission electron microscope image (HRTEM) of the core-shell structure V ₂ O ₃ /VO _2-x ;

Figure 6b is a high-resolution transmission electron microscope image (HRTEM) at the interface of V ₂ O ₃ and VO _2-x ;

Figure 6c is a high-angle annular dark-field detector scanning transmission electron microscope (HAADF-STEM) image of VO _2-x crystal.

Fig. 7 is a diagram of the electrochemical data of the three-dimensional nanoporous V ₂ O ₃ /VO _2-x layered vanadium oxide electrode prepared in Example 1 of the present invention at a voltage window of 0-1.4V; wherein:

Figure 7a is the cyclic voltammetry curves of the three-dimensional nanoporous V ₂ O ₃ /VO _2-x layered vanadium oxide electrode at the voltage window of 0-1.4V and 0-0.8V, and the scan rate of 50mV s ^-1 ;

Figure 7b is the cyclic voltammetry curve of the three-dimensional nanoporous V ₂ O ₃ /VO _2-x layered vanadium oxide electrode at a voltage window of 0-1.4V and a scan rate of 5-100mV s ^-1 ;

Fig. 7c is a graph of self-discharge of three-dimensional nanoporous V ₂ O ₃ , VO ₂ , V ₂ O ₃ /VO _2-x layered vanadium oxide electrodes;

Figure 7d is the cycle stability curve of the three-dimensional nanoporous V ₂ O ₃ /VO _2-x layered vanadium oxide electrode in the voltage window of 0-1.4V, the inset is the constant current density of 130A cm ^-3 Current charge and discharge curves.

Fig. 8 is the electrochemical data of the three-dimensional nanoporous V ₂ O ₃ /VO _2-x layered vanadium oxide electrode prepared in Example 1 of the present invention at a voltage window of 0-1.4V and other materials in the prior art Electrode comparison graph; where:

Fig. 8a is a comparison curve of the mass and volume specific capacity of the three-dimensional nanoporous V ₂ O ₃ /VO _2-x layered vanadium oxide electrode and other material electrodes in the prior art at different scan rates;

Fig. 8b is a comparative graph of the energy density and power density of the three-dimensional nanoporous V ₂ O ₃ /VO _2-x layered vanadium oxide electrode and electrodes of other materials in the prior art.

detailed description

In order to further illustrate the technical solution of the present invention, in conjunction with the accompanying drawings, the specific implementation of the present invention is as follows:

Implementation example 1:

The preparation method of the layered transition metal oxide electrode supercapacitor based on the phase change induction of the present invention, taking vanadium oxide as an example, the specific steps are as follows:

a. The stainless steel metal base is fully cleaned in acid solution, deionized water and ethanol in turn, and vacuum-dried;

B. getting an appropriate amount of mass volume percent concentration is 5% polystyrene solution colloidal solution dripped on the stainless steel surface, and evaporated the colloidal solution under the environment of 70 ℃ to make polystyrene (PS) film, as shown in Figure 1a, the The made polystyrene (PS) film will be used as the template for electrochemical deposition;

c. Preparation of three-dimensional nanoporous V ₂ O ₃ :

A three-electrode system is adopted, the working electrode is a PS film with a stainless steel substrate, the counter electrode is a platinum electrode, and Ag/AgCl is used as a reference electrode.

The electrolyte solution contains 0.5mol/L VOSO ₄ , 0.5mM H ₂ SO ₄ , 30mL H ₂ O and 40mL LC ₂ H ₅ OH, the deposition condition voltage is 1.6V, and the deposition time is 100s to form an organic metal oxide mixture, as shown in the figure As shown in 1b; then the sample is placed in a tube furnace and heated to 500°C in a H ₂ /Ar gas mixture with a volume fraction of 5% H ₂ to remove the PS template and obtain a three-dimensional nanoporous V ₂ O ₃ , as shown in Fig. 1c shown.

d. Preparation of three-dimensional nanoporous layered vanadium oxide electrodes:

Put this three-dimensional porous V ₂ O ₃ electrode into a tube furnace and heat it to 400°C for 30 minutes. The phase transition is induced by heat, so that the surface of V ₂ O ₃ with diamond phase grows in situ with VO _2-x film with rutile phase. , as shown in Figure 1d.

e. Combine the prepared two V ₂ O ₃ /VO _2-x layered vanadium oxide electrodes symmetrically on both sides of a cotton fiber paper separator, and assemble it into a supercapacitor for direct application in energy storage, as shown in Figure 1e Show.

Implementation example 2:

The preparation method of the layered transition metal oxide electrode supercapacitor based on the phase change induction of the present invention, taking vanadium oxide as an example, the specific steps are as follows:

a. is identical with step a in the implementation example 1;

B. is identical with the b step in the implementation example 1;

c. the same as the c step in the implementation example 1;

d. Preparation of three-dimensional nanoporous layered vanadium oxide electrodes:

Put this three-dimensional porous V ₂ O ₃ electrode into a tube furnace and heat it to 400°C for 60 minutes. The phase transformation is induced by heat, so that the surface of V ₂ O ₃ with diamond phase grows in situ and VO _2-x film with rutile phase .

e. It is the same as step e in the implementation example 1.

Implementation example 3:

The preparation method of the layered transition metal oxide electrode supercapacitor based on the phase change induction of the present invention, taking vanadium oxide as an example, the specific steps are as follows:

a. is identical with step a in the implementation example 1;

B. is identical with the b step in the implementation example 1;

c. is identical with the c step in the implementation example 1;

d. Preparation of three-dimensional nanoporous layered vanadium oxide electrodes:

Put this three-dimensional porous V ₂ O ₃ electrode into a tube furnace and heat it to 400°C for 80 minutes, and a phase transition occurs through thermal induction, so that the V ₂ O ₃ surface with a diamond phase grows in situ and a VO _2-x film with a rutile phase .

e. It is the same as step e in the implementation example 1.

Implementation example 4:

The preparation method of the layered transition metal oxide electrode supercapacitor based on the phase change induction of the present invention, taking vanadium oxide as an example, the specific steps are as follows:

a. is identical with step a in the implementation example 1;

B. is identical with the b step in the implementation example 1;

c. is identical with the c step in the implementation example 1;

d. Preparation of three-dimensional nanoporous layered vanadium oxide electrodes:

The three-dimensional porous V ₂ O ₃ electrode was placed in a tube furnace and heated to 400°C for 120 min. The phase transition was induced by heat, so that VO _2-x film with rutile phase was grown in situ on the surface of V ₂ O ₃ with diamond phase.

e. It is the same as step e in the implementation example 1.

Implementation example 5:

The preparation method of the layered transition metal oxide electrode supercapacitor based on the phase change induction of the present invention, taking vanadium oxide as an example, the specific steps are as follows:

a. is identical with step a in the implementation example 1;

B. is identical with the b step in the implementation example 1;

c. is identical with the c step in the implementation example 1;

d. Preparation of three-dimensional nanoporous layered vanadium oxide electrodes:

The three-dimensional porous V ₂ O ₃ electrode was placed in a tube furnace and heated to 400°C for 600 min. A phase transformation occurs through thermal induction so that V ₂ O ₃ with diamond phase is completely transformed into VO ₂ in rutile phase.

e. It is the same as step e in the implementation example 1.

Implementation example 6:

The preparation method of the layered transition metal oxide electrode supercapacitor based on the phase change induction of the present invention, taking vanadium oxide as an example, the specific steps are as follows:

a. is identical with step a in the implementation example 1;

B. is identical with the b step in the implementation example 1;

c. is identical with the c step in the implementation example 1;

d. The same as step e in the implementation example 1.

In the above 6 groups of examples, the comparison of the effects of different heat treatment conditions on the properties of the prepared transition metal oxide electrodes is shown in Table 1 below:

Table 1

The present invention also provides a testing method based on a phase change-induced layered transition metal oxide electrode supercapacitor, which is prepared by the aforementioned method, Described test method is electrochemical test method, and concrete process is as follows:

During the electrochemical testing of the supercapacitor prepared according to the aforementioned method, the assembled supercapacitor based on the phase transition-induced layered transition metal oxide electrode was directly immersed in a ₁ mol/L _Na2SO4 solution, and the voltammetry The voltage range of the characteristic curve is set at -0.8～+0.8V and 0～1.4V respectively for testing. During this process, change the scan rate to obtain cyclic voltammetry curves at different scan rates, charge and discharge for a long time at a constant current density to obtain cycle stability data, and after the capacitor is fully charged, continue to test the self-discharge of the supercapacitor at the open circuit voltage performance.

Taking the aforementioned Example 1 as an example, the structural characterization and composition selection of the three-dimensional nanoporous V ₂ O ₃ /VO _2-x layered vanadium oxide electrode material as a supercapacitor are as follows:

As shown in FIG. 2 , the microstructure and specific surface area of the three-dimensional nanoporous V ₂ O ₃ /VO _2-x layered vanadium oxide electrode prepared in Example 1 were analyzed by scanning electron microscopy (SEM).

As shown in Figure 2, the prepared porous electrode thickness is 2um;

As shown in Figures 2b, 2c, 2d and 2e, the prepared three-dimensional nanoporous V ₂ O ₃ /VO _2-x layered vanadium oxide electrode has pores of various sizes and the three-dimensional porous structure effectively increases the specific surface area of the active material. ;

As shown in Figures 2f and 2g, the nitrogen adsorption-desorption curves further prove that the electrode material prepared by the method of the present invention has a high specific surface area (99.8m ² g ^-1 ), and at the same time the main The pore sizes are distributed at ~4nm, ~10nm and ~70nm.

As shown in Figure 3, three-dimensional nanoporous V ₂ O ₃ , VO ₂ , V ₂ O ₃ /VO _2-x electrodes were characterized by X-ray diffraction (XRD), as shown in the figure, through the aforementioned Example 1 The V ₂ O ₃ /VO _2-x electrodes prepared in Example 4 have continuous composition changes, which provides the possibility to determine the composition with the best electrochemical performance.

As shown in Figure 4, the cyclic voltammetry test was carried out at a scanning speed range of 5 to 1000mV s ^-1 and a voltage range of -0.8 to +0.8V, and obtained in the aforementioned examples 1 to 4 through different heat treatment times Comparison of the volume specific capacity of the prepared V ₂ O ₃ /VO _2-x electrodes.

_{As shown} in _{Figure 5} , _{the super} The electrochemical performance of capacitors is compared as follows:

Comparison of cyclic voltammetry curves of three-dimensional nanoporous V ₂ O ₃ , VO ₂ , V ₂ O ₃ /VO _2-x layered vanadium oxide electrodes at a scan rate of 50 mV s ^-1 as shown in Fig. 5a;

As shown in Figure 5b, the cyclic voltammetry test was performed at a scanning speed range of 5 to 1000mV s ^-1 and a voltage range of -0.8 to +0.8V, and the three-dimensional nanoporous V ₂ O ₃ , VO ₂ , V ₂ Comparison of volume specific capacity of O ₃ /VO _2-x layered vanadium oxide electrodes.

As mentioned above, the electrochemical performance of the three-dimensional nanoporous V ₂ O ₃ /VO _2-x layered vanadium oxide electrode has obvious advantages compared with the three-dimensional nanoporous V ₂ O ₃ , VO ₂ electrode. Therefore, the V ₂ O ₃ /VO _2-x layered vanadium oxide electrode prepared in Example 1 was selected for further research.

As shown in Figure 6, the V ₂ O ₃ /VO _2-x vanadium oxide was characterized by scanning transmission electron microscopy (HAADF-STEM) with a high-angle annular dark field detector;

As shown in Figure 6a, the VO 2-x on the surface of the prepared V ₂ O ₃ /VO 2 _{- x} layered vanadium oxide electrode material is uniformly covered;

As shown in Figure 6b, the prepared V ₂ O ₃ /VO _2-x layered vanadium oxide electrode material presents a coherent interface between VO _2-x and V ₂ O ₃ , which greatly reduces the interaction between the two components. Contact resistance;

As shown in Figure 6c, the VO 2-x in the prepared V ₂ O ₃ /VO 2 _{- x} layered vanadium oxide electrode material has regular oxygen vacancies and forms channels to facilitate the entry and storage of cations, which can be simultaneously The overall electrochemical performance is greatly enhanced by utilizing two forms of pseudocapacitance, intercalation type and surface redox type.

The electrochemical test results of the supercapacitor composed of the V ₂ O ₃ /VO _2-x layered vanadium oxide electrodes prepared in the foregoing example 1 are as follows:

As shown in Figure 7a, when the scanning speed is 50mV s ^-1 , the cyclic voltammetry characteristic curve test is carried out in the voltage range of 0-0.8V and 0-1.4V respectively. From the CV curve in the figure, it can be seen that when the voltage window is from From 0.8V to 1.4V, there is no obvious redox peak of water splitting, which indicates that the microstructure of the prepared V ₂ O ₃ /VO _2-x electrode can effectively suppress the generation of water splitting, which is conducive to improving the energy of the capacitor density;

As shown in Figure 7b, when the voltage window is 0-1.4V, the CV curve under the scanning rate range of 5-100mV s ^-1 , when the scanning rate reaches 100mV s ^-1 , the volt-ampere characteristic curve can still maintain a rectangular shape, This shows that sufficient oxygen reduction reaction can still take place at this scanning speed, indicating that the supercapacitor prepared by the method of the present invention has good rate performance;

As shown in Figure 7c, in the self-discharge coefficient comparison of three-dimensional nanoporous V ₂ O ₃ , VO ₂ , V ₂ O ₃ /VO _2-x layered vanadium oxide supercapacitors at 1.4V, after 10h of continuous testing, V The lowest self-discharge coefficient of the ₂ O ₃ /VO _2-x layered vanadium oxide supercapacitor is 6.4mV h ^-1 , which is due to the fact that the electrode material prepared by the method of the present invention has a core-shell structure with a large number of oxygen vacancies and can Stable storage of cations can inhibit the occurrence of self-discharge to a certain extent;

As shown in Figure 7d, the cycle stability process of the three-dimensional nanoporous V ₂ O ₃ /VO _2-x layered vanadium oxide supercapacitor was tested in the voltage range of 0-1.4V and the current density of 130A cm ^-3 galvanostatic charge-discharge test Among them, the test 15,000 times charge and discharge capacity retention rate is as high as 93%.

As shown in Figure 8a, the volume and mass specific capacity of the V ₂ O ₃ /VO _2-x layered vanadium oxide electrode prepared in Example ¹ of the present invention is comparable to other Compared with the electrode materials in the prior art, the V ₂ O ₃ /VO _2-x layered vanadium oxide electrode prepared by the present invention exhibits a specific capacity much higher than that of other materials, which is mainly due to the The electrode material prepared by the above method not only ensures the electrical conductivity, but also designs a VO _2-x layer with a reasonable concentration of oxygen vacancies. The existence of oxygen vacancies greatly improves the ability of cations to enter the interior of the crystal, resulting in And the surface is effectively used at the same time to improve the specific capacity of the electrode material;

As shown in Figure 8b, the three-dimensional nanoporous V ₂ O ₃ /VO _2-x layered vanadium oxide electrode supercapacitor prepared in Example 1 of the present invention and the supercapacitor volumetric energy density and power density in the prior art In comparison, the maximum energy density and power density of the supercapacitor prepared by the method of the present invention reach 330mWh cm ^-3 and 280W cm ^-3 respectively, and the comprehensive performance is the best among the existing supercapacitors.

Claims (5)

1. The preparation method based on the layered transition group metal oxide electrode supercapacitor induced by phase change, said method is to symmetrically assemble the layered transition group metal oxide electrode induced by phase change on both sides of the diaphragm, characterized in that : The preparation steps of the layered transition metal oxide electrode induced by the phase change are as follows: a. The metal foil substrate is fully cleaned in acid solution, deionized water and ethanol in sequence, and vacuum-dried; b. Using polystyrene microspheres on the metal foil substrate, a polystyrene film is obtained by heating and evaporating, as a template for further electrochemical deposition; c. Electrodeposit transition metal oxide precursors on polystyrene films, and remove polystyrene films under reducing atmosphere and high temperature conditions to obtain three-dimensional nanoporous transition metal oxides; d. Put the three-dimensional nanoporous transition metal oxide into a tube furnace, heat and keep warm to obtain a layered transition metal oxide electrode induced by phase transition. 2. the preparation method of the layered transition metal oxide electrode supercapacitor based on phase change induction as claimed in claim 1, is characterized in that: In the step b, the mass volume percent concentration of polystyrene microspheres is 0.2-20%, the temperature of heating and evaporating is 40-95° C., and the thickness of the obtained polystyrene film is 2-30 μm. 3. the preparation method of the layered transition metal oxide electrode supercapacitor based on phase change induction as claimed in claim 1, is characterized in that: The high temperature condition in the step c is a temperature of 100-800° C. and a time of 0-10 hours. 4. a kind of preparation method based on the super capacitor of layered vanadium oxide electrode induced by phase change as claimed in claim 1, is characterized in that: The transition group metal oxide is V ₂ O ₃ , VO ₂ , TiO ₂ , ZnO, RuO, MnO ₂ , MoO ₂ , CuO or NbO ₂ , and the annealing conditions are 100-800° C. for 0-10 hours. 5. based on the testing method of the layered transition metal oxide electrode supercapacitor induced by phase change, it is characterized in that: The supercapacitor is a layered transition metal oxide electrode supercapacitor induced by a phase change as prepared by any one of claims 1-4, and the test method is an electrochemical test method, specifically testing The process is: immerse the supercapacitor in 1mol/L Na ₂ SO ₄ solution, set the interval of the volt-ampere characteristic curve at -0.8V～+0.8V or 0～1.4V, and change the scan rate to obtain different scan rates Under the cyclic voltammetry curve; under constant current density for a long time charge and discharge to obtain cycle stability data; after the capacitor is fully charged, the self-discharge performance of the supercapacitor is continuously tested under the open circuit voltage.