Water-containing ruthenium oxide positive electrode material with high specific capacitance and preparation method and application of water-containing ruthenium oxide positive electrode material

Abstract

The invention is applicable to the technical field of energy storage devices, and provides a preparation method of a high-specific-capacitance hydrous ruthenium oxide positive electrode material, which comprises the following steps: carrying out annealing treatment on RuO2.xH2O, preparing RuO2.xH2O powder, a binder and a conductive agent into slurry, stirring, coating carbon paper with the slurry, and carrying out vacuum drying; a three-electrode system is used, dried carbon paper loaded with RuO2.xH2O powder is used as a working electrode, an activation process is carried out, and the activation mode is one of constant-current intermittent titration activation, cyclic voltammetry activation and constant-current charge-discharge activation. The invention further provides the high-specific-capacitance hydrous ruthenium oxide positive electrode material and application thereof. According to the method, the annealing temperature is reduced, and a part of crystal water in the water-containing ruthenium oxide is reduced, so that the crystal water reaches a proper degree; and the crystallinity of the water-containing ruthenium oxide is reduced through electrochemical constant-current intermittent titration circulation, so that electron transport and ion transport reach the most coordinated state, and the specific capacitance of the positive electrode material is further improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage devices, and in particular relates to a high specific capacitance hydrous ruthenium oxide positive electrode material and a preparation method and application thereof. Background Art

[0002] In recent years, mankind has been seeking sustainable clean energy, such as solar energy, wind energy, tidal energy, etc., but compared with traditional fossil fuel power generation, new energy generation is intermittent and cannot continuously provide stable power output. Therefore, a stable power storage system is very important. Pseudocapacitors can achieve high energy density and high power density through a single electrode, and pseudocapacitors use reversible surface or near-surface Faraday reactions to store charge, which enables them to exceed the capacity limit of double-layer capacitors and the mass transfer limit of batteries. Among them, RuO2 is one of the typical pseudocapacitor materials. The specific capacitance of hydrous ruthenium oxide RuO2·xH2O is better than that of non-hydrous RuO2, but the current preparation methods have their own shortcomings.

[0003] Among them, the sol-gel method has a complex reaction process and requires precise control of the conditions of each reaction step. The water content of ruthenium oxide cannot be controlled and the long drying time affects the preparation efficiency. The selection of potential and the control of electrodeposition time in the electrodeposition method are relatively complex, and it is difficult to control the quality of electrodeposition. In addition, the electrodeposition method requires the selection of a suitable current collector. Summary of the invention

[0004] The purpose of the embodiments of the present invention is to provide a method for preparing a high specific capacitance hydrous ruthenium oxide positive electrode material, aiming to solve the problems raised in the above background technology.

[0005] The embodiment of the present invention is implemented as follows: a method for preparing a high specific capacitance hydrous ruthenium oxide positive electrode material comprises the following steps:

[0006] (1) annealing RuO2·xH2O to obtain RuO2·xH2O powder, preparing the RuO2·xH2O powder with a binder and a conductive agent into a slurry, stirring the slurry, coating the slurry on carbon paper, and vacuum drying the slurry;

[0007] (2) Using a three-electrode system, with dried carbon paper loaded with RuO2·xH2O powder as the working electrode, a saturated calomel electrode as the reference electrode, and a platinum sheet electrode as the counter electrode, an activation process is performed to obtain a high specific capacitance hydrous ruthenium oxide positive electrode material, wherein the activation method is one of constant current intermittent titration activation, cyclic voltammetry activation, and constant current charge and discharge activation.

[0008] Preferably, in step (1), the annealing treatment is carried out at a temperature of 120° C. and for 18 hours.

[0009] Preferably, in step (1), the binder is a nafion membrane solution, and the conductive agent is conductive graphite.

[0010] Preferably, in step (1), the mass ratio of the nafion membrane solution, the conductive graphite and the RuO2·xH2O powder is 1:1:8.

[0011] Preferably, in step (2), the activation method is constant current intermittent titration activation, specifically: performing 5-10 cycles of constant current intermittent titration activation.

[0012] Another object of an embodiment of the present invention is to provide a high specific capacitance hydrous ruthenium oxide positive electrode material, which is prepared by the above-mentioned preparation method.

[0013] Another object of an embodiment of the present invention is to provide an application of a high specific capacitance hydrous ruthenium oxide positive electrode material in the preparation of a pseudocapacitor supercapacitor.

[0014] The embodiment of the present invention provides a method for preparing a high specific capacitance hydrous ruthenium oxide positive electrode material, which improves the traditional high-temperature annealing method. The method is simple and safe, lowers the annealing temperature, and reduces a portion of the crystal water in the commercial hydrous ruthenium oxide to a suitable level of crystal water; then, the crystallinity of the hydrous ruthenium oxide is reduced through an electrochemical constant current intermittent titration cycle so that the electron transfer and ion transport reach the most coordinated state, thereby significantly improving the specific capacitance of the prepared positive electrode material; in addition, the preparation method is simple and safe to operate, and the specific capacitance is controllable, and constant current intermittent titration activation for different numbers of cycles can be used to achieve different specific capacitance requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The XRD patterns of the samples prepared in Example 1 and Comparative Example 1 of the present invention are shown in FIG.

[0016] Figure 2 The SEM images of the samples prepared in Example 1 and Comparative Example 1 of the present invention are shown in FIG.

[0017] Figure 3 TEM images of samples prepared in Example 1 of the present invention and Comparative Example 1 (the upper image is 120°C / 18h-original, and the lower image is 120°C / 18h-final);

[0018] Figure 4 Cyclic voltammetry curves of samples prepared in Example 1 and Comparative Example 1 of the present invention;

[0019] Figure 5 The constant current charge and discharge curves of the samples prepared in Example 1 and Comparative Example 1 of the present invention;

[0020] Figure 6The constant current charge and discharge curves of the samples prepared in Example 2, Example 3 and Example 4 of the present invention. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0022] The specific implementation of the present invention is described in detail below in conjunction with specific embodiments.

[0023] Embodiment 1: A high specific capacitance hydrous ruthenium oxide positive electrode material, the preparation method of which comprises the following steps:

[0024] 20 mg of RuO2·xH2O was annealed at 120°C for 18 h, and the obtained RuO2·xH2O powder was mixed with DuPont nafion D520 membrane solution and conductive graphite in a mass ratio of DuPont nafion D520 membrane solution: conductive graphite: RuO2·xH2O powder = 1:1:8 to form a slurry, stirred for 12 h, coated on 1 cm*1.5 cm carbon paper with a coating area of ​​1 cm*1 cm, and vacuum dried; a three-electrode system was used, with the carbon paper loaded with RuO2·xH2O powder as the working electrode, a saturated calomel electrode as the reference electrode, and a platinum sheet electrode as the counter electrode, and a constant current intermittent titration test activation was performed for about 10 cycles, and the obtained sample was recorded as 120°C / 18h-final.

[0025] Embodiment 2: A high specific capacitance hydrous ruthenium oxide positive electrode material, the preparation method of which comprises the following steps:

[0026] 20 mg of RuO2·xH2O was annealed at 120°C for 18 h, and the obtained RuO2·xH2O powder was prepared into a slurry with DuPont nafion D520 membrane solution and conductive graphite in a mass ratio of DuPont nafion D520 membrane solution: conductive graphite: RuO2·xH2O powder = 1:1:8, stirred for 12 h, coated on 1 cm*1.5 cm carbon paper with a coating area of ​​1 cm*1 cm, and vacuum dried; a three-electrode system was used, with the carbon paper loaded with RuO2·xH2O powder as the working electrode, the saturated calomel electrode as the reference electrode, and the platinum sheet electrode as the counter electrode, and a constant current intermittent titration test activation was performed for about 5 cycles, and the obtained sample was recorded as GITT5cycles.

[0027] Example 3 is different from Example 2 in that the activation method is changed to cyclic voltammetry (CV) activation, and the activation is also performed for about 5 cycles. The obtained sample is CV 5 cycles.

[0028] Example 4 is different from Example 2 in that the activation method is changed to constant current charge and discharge (GCD) activation, and the activation is also performed for about 5 cycles. The obtained sample is GCD 5 cycles.

[0029] Comparative Example 1: A hydrous ruthenium oxide positive electrode material, the preparation method of which comprises the following steps:

[0030] 20 mg of RuO2·xH2O was annealed at 120°C for 18 h, and the obtained RuO2·xH2O powder was mixed with DuPont nafion D520 membrane solution and conductive graphite in a mass ratio of DuPont nafion D520 membrane solution: conductive graphite: RuO2·xH2O powder = 1:1:8 to form a slurry, stirred for 12 h, coated on 1 cm*1.5 cm carbon paper with a coating area of ​​1 cm*1 cm, and vacuum dried. The obtained sample was recorded as 120°C / 18 h-original.

[0031] Performance Testing:

[0032] The samples prepared in Example 1 and Comparative Example 1 were analyzed by X-ray diffractometer, and the XRD patterns were as follows: Figure 1 As shown, according to Figure 1 It can be seen that the sample has no obvious RuO2 characteristic peak, which is actually due to the small size of the sample particles. The scanning electron microscope is used for analysis and the scanning image is as follows: Figure 2 As shown, according to Figure 2 It can be seen that the sample morphology did not change significantly before and after activation, and the overall size of the nanoparticles was small. The transmission electron microscope was used to analyze the sample, and the transmission electron microscope image was obtained. Figure 3 As shown, according to Figure 3 It can be seen that the crystallinity of the sample after GITT activation is reduced. This is because the activation causes the nanoparticles and the crystal water around them to reach a state of equilibrium. The nanoparticles transmit electrons, and the crystal water distributed around them transports protons. The transport of protons and the conduction of electrons reach the optimal state, which significantly improves the performance.

[0033] The samples prepared in Example 1 and Comparative Example 1 were subjected to electrochemical performance tests, and the cyclic voltammetry curves were obtained as shown in FIG. Figure 4 As shown, the constant current charge and discharge curve is as follows Figure 5 As shown, according to Figures 4 to 5 It can be seen that the specific capacitance of the sample after 10 cycles of GITT activation is significantly improved and can reach the best, with a specific capacitance of about 760F / g;

[0034] The samples prepared in Example 2 to Example 4 were subjected to electrochemical tests respectively, and the constant current charge-discharge curves were obtained as shown in FIG. Figure 6 As shown, it can be seen that the efficiencies of CV activation and GCD activation are poorer than those of GITT activation.

[0035] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a high specific capacitance hydrous ruthenium oxide positive electrode material, characterized in that: The following steps are involved: (1) annealing RuO2·xH2O to obtain RuO2·xH2O powder, preparing the RuO2·xH2O powder with a binder and a conductive agent into a slurry, stirring the slurry, coating the slurry on carbon paper, and vacuum drying the slurry; (2) Using a three-electrode system, with dried carbon paper loaded with RuO2·xH2O powder as the working electrode, a saturated calomel electrode as the reference electrode, and a platinum sheet electrode as the counter electrode, an activation process is performed to obtain a high specific capacitance hydrous ruthenium oxide positive electrode material, wherein the activation method is one of constant current intermittent titration activation, cyclic voltammetry activation, and constant current charge and discharge activation.

2. The method for preparing a high specific capacitance hydrous ruthenium oxide positive electrode material according to claim 1, characterized in that: In step (1), the annealing treatment is carried out at a temperature of 120° C. and for 18 hours.

3. The method for preparing a high specific capacitance hydrous ruthenium oxide positive electrode material according to claim 1, characterized in that: In step (1), the binder is a nafion membrane solution, and the conductive agent is conductive graphite.

4. The method for preparing a high specific capacitance hydrous ruthenium oxide positive electrode material according to claim 3, characterized in that: In step (1), the mass ratio of the nafion membrane solution, the conductive graphite and the RuO2·xH2O powder is 1:1:

8.

5. The method for preparing a high specific capacitance hydrous ruthenium oxide positive electrode material according to claim 1, characterized in that: In step (2), the activation method is constant current intermittent titration activation, specifically: performing 5-10 cycles of constant current intermittent titration activation.

6. A high specific capacitance hydrous ruthenium oxide positive electrode material, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the high specific capacitance hydrous ruthenium oxide positive electrode material as claimed in claim 6 in the preparation of pseudocapacitor supercapacitors.

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