A high specific capacitance hydrated ruthenium oxide cathode material, its preparation method, and its applications.

Abstract

This invention relates to the field of energy storage device technology and provides a method for preparing a high-specific-capacitance hydrated ruthenium oxide cathode material, comprising the following steps: annealing RuO2·xH2O; preparing a slurry by mixing RuO2·xH2O powder with a binder and a conductive agent, stirring, coating it onto carbon paper, and vacuum drying; using a three-electrode system, with the dried carbon paper loaded with RuO2·xH2O powder as the working electrode, performing an activation process, wherein the activation method is one of constant current intermittent titration activation, cyclic voltammetry activation, and constant current charge-discharge activation. This invention also provides a high-specific-capacitance hydrated ruthenium oxide cathode material and its application. This invention lowers the annealing temperature, reducing some of the crystal water in the hydrated ruthenium oxide to a suitable level; then, by using electrochemical constant current intermittent titration cycles to reduce the crystallinity of the hydrated ruthenium oxide, electron transport and ion transport reach the most coordinated state, thereby improving the specific capacitance of the cathode material.

Description

Technical Field

[0001] This invention belongs to the field of energy storage device technology, and particularly relates to a high specific capacitance hydrated ruthenium oxide cathode material, its preparation method, and its application. Background Technology

[0002] In recent years, humanity has been seeking clean energy sources for sustainable development, such as solar, wind, and tidal energy. However, compared to traditional fossil fuel power generation, new energy power generation is intermittent and cannot continuously provide stable power output. Therefore, stable energy storage systems are crucial. Pseudocapacitive supercapacitors can achieve high energy density and high power density through a single electrode. Furthermore, pseudocapacitive supercapacitors utilize reversible surface or near-surface Faraday reactions to store charge, enabling them to overcome the capacity limitations of double-layer capacitors and the mass transfer limitations of batteries. RuO2 is a typical pseudocapacitive material, and hydrated ruthenium oxide RuO2·xH2O exhibits better specific capacitance than anhydrous RuO2. However, current preparation methods each have their shortcomings.

[0003] Among them, the sol-gel method has a complex reaction process, which requires precise control of the conditions of each reaction step. It is impossible to control the water content of ruthenium oxide and the long drying time affects the preparation efficiency. On the other hand, the selection of potential and control of electrodeposition time in the electrodeposition method are more complex, making it 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 this invention is to provide a method for preparing a high specific capacitance hydrated ruthenium oxide cathode material, aiming to solve the problems mentioned in the background art.

[0005] The present invention is implemented as follows: a method for preparing a high specific capacitance hydrated ruthenium oxide cathode material includes the following steps:

[0006] (1) RuO2·xH2O is annealed to obtain RuO2·xH2O powder. The RuO2·xH2O powder is mixed with binder and conductive agent to form a slurry, stirred, coated on carbon paper, and vacuum dried.

[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 carried out to obtain a high specific capacitance hydrated ruthenium oxide cathode material. The activation method is one of constant current intermittent titration activation, cyclic voltammetry activation, and constant current charge-discharge activation.

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

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

[0010] Preferably, in step (1), the mass ratio of the Nafion membrane solution, conductive graphite, and 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 objective of this invention is to provide a high specific capacitance hydrated ruthenium oxide cathode material, which is prepared using the above-described preparation method.

[0013] Another objective of this invention is to provide an application of a high specific capacitance hydrated ruthenium oxide cathode material in the fabrication of pseudocapacitive supercapacitors.

[0014] This invention provides a method for preparing a high-specific-capacitance hydrated ruthenium oxide cathode material. This method improves upon the traditional high-temperature annealing method, making it simpler and safer. It lowers the annealing temperature, reducing some of the water of crystallization in commercially available hydrated ruthenium oxide and bringing the water of crystallization to a suitable level. Furthermore, it uses electrochemical constant-current intermittent titration cycles to further reduce the crystallinity of the hydrated ruthenium oxide, achieving optimal coordination between electron transport and ion transport, thereby significantly improving the specific capacitance of the prepared cathode material. In addition, the preparation method is simple and safe to operate, and the specific capacitance is controllable. Different numbers of activation cycles using constant-current intermittent titration can be used to achieve different specific capacitance requirements. Attached Figure Description

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

[0016] Figure 2 SEM images of the samples prepared in Example 1 and Comparative Example 1 of this invention;

[0017] Figure 3 The images are TEM images of the samples prepared in Example 1 and Comparative Example 1 of this invention (the top image is 120℃ / 18h-original, and the bottom image is 120℃ / 18h-final).

[0018] Figure 4 The cyclic voltammetry curves of the samples prepared in Example 1 and Comparative Example 1 of this invention are shown.

[0019] Figure 5 The constant current charge-discharge curves of the samples prepared in Example 1 and Comparative Example 1 of this invention are shown.

[0020] Figure 6The constant current charge-discharge curves are for the samples prepared in Examples 2, 3 and 4 of this invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0022] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0023] Example 1: A high specific capacitance hydrated ruthenium oxide cathode material, the preparation method of which includes the following steps:

[0024] 20 mg of RuO2·xH2O was annealed at 120℃ for 18 h. The resulting RuO2·xH2O powder was mixed with DuPont Nafion D520 film solution and conductive graphite in a mass ratio of DuPont Nafion D520 film solution: conductive graphite: RuO2·xH2O powder = 1:1:8 to form a slurry. The mixture was stirred for 12 h and coated onto 1 cm*1.5 cm carbon paper with a coating area of ​​1 cm*1 cm. The coating was then 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. The constant current intermittent titration test was performed for about 10 cycles to activate the sample. The resulting sample was recorded as 120℃ / 18h-final.

[0025] Example 2: A high specific capacitance hydrated ruthenium oxide cathode material, the preparation method of which includes the following steps:

[0026] 20 mg of RuO2·xH2O was annealed at 120 °C for 18 h. The resulting RuO2·xH2O powder was mixed with DuPont Nafion D520 film solution and conductive graphite in a mass ratio of DuPont Nafion D520 film solution: conductive graphite: RuO2·xH2O powder = 1:1:8 to form a slurry. The mixture was stirred for 12 h and coated onto 1 cm * 1.5 cm carbon paper, with a coating area of ​​1 cm * 1 cm. The mixture was then 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. Activation was performed by constant current intermittent titration for about 5 cycles. The resulting sample was recorded as GITT5 cycles.

[0027] Example 3 differs from Example 2 in that the activation method is changed. Cyclic voltammetry (CV) is used for activation, and the same process is repeated for about 5 cycles. The resulting sample is CV 5 cycles.

[0028] Example 4 differs from Example 2 in that the activation method is changed. Constant current charge-discharge (GCD) activation is used, and the same process is performed for about 5 cycles. The resulting sample is the GCD 5cycles.

[0029] Comparative Example 1: A hydrated ruthenium oxide cathode material, the preparation method of which includes the following steps:

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

[0031] Performance testing:

[0032] The samples prepared in Example 1 and Comparative Example 1 were analyzed using an X-ray diffractometer, and the XRD patterns are shown below. Figure 1 As shown, according to Figure 1 It can be seen that the sample does not have obvious RuO2 characteristic peaks, which is actually due to the small particle size of the sample; analysis using scanning electron microscopy yielded the following scan image. Figure 2 As shown, according to Figure 2 It can be seen that the morphology of the samples did not change significantly before and after activation, and the overall nanoparticle size was relatively small; transmission electron microscopy (TEM) analysis yielded the following transmission images: 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 activation leads to an equilibrium between the nanoparticles and the surrounding water of crystallization. The nanoparticles transport electrons, and the water of crystallization 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 follows: Figure 4 As shown, the constant current charge-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 optimal level, with a specific capacitance of about 760 F / g.

[0034] The samples prepared in Examples 2-4 were subjected to electrochemical tests, and the constant current charge-discharge curves were obtained as follows: Figure 6 As shown, the activation efficiencies of CV and GCD are relatively poor compared to 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 within the protection scope of the present invention.

Claims

1. A method for preparing a high specific capacitance hydrated ruthenium oxide cathode material, characterized in that, Includes the following steps: (1) The RuO2·xH2O is annealed at a temperature of 120°C for 18 hours to obtain RuO2·xH2O powder. The RuO2·xH2O powder is mixed with binder and conductive agent to form a slurry, stirred, coated on carbon paper, and vacuum dried. (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 carried out to obtain a high specific capacitance hydrated ruthenium oxide cathode material. The activation method is to perform 5-10 cycles of constant current intermittent titration.

2. The method for preparing the high specific capacitance hydrated ruthenium oxide cathode material according to claim 1, characterized in that, In step (1), the binder is Nafion film solution and the conductive agent is conductive graphite.

3. The method for preparing the high specific capacitance hydrated ruthenium oxide cathode material according to claim 2, characterized in that, In step (1), the mass ratio of the Nafion membrane solution, conductive graphite and RuO2·xH2O powder is 1:1:

8.

4. A high specific capacitance hydrated ruthenium oxide cathode material, characterized in that, It is prepared using the preparation method described in any one of claims 1-3.

5. The application of the high specific capacitance hydrated ruthenium oxide cathode material as described in claim 4 in the preparation of pseudocapacitive supercapacitors.

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