Preparation of RuO2-Ta2O5/Ti electrode for supercapacitor in ionic liquid

• Main Authors: Kai-Hsiang Hsu, 許凱翔
• Other Authors: Sheng-Wei Lee
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/2q97y4

碩士 === 國立中央大學 === 材料科學與工程研究所 === 107 === In this study we synthesized RuO2-Ta2O5/Ti electrode for supercapacitors by thermal decomposition method. The influence of annealing temperature and precursor effect to the pseudocapacitive behavior of electrode were investigated systematically. In first part. The result shows that the annealing temperature at 250 OC electrode is unstable in 0.5 M H2SO4 electrolyte. While decomposition temperature increase to 300, 350, 400 OC, electrodes become stable. From XRD and XPS analysis while decomposition temperature increases, crystallinity of rutile RuO2 also increases, and the amount of hydrous-RuO2(RuO2 xH2O) is decreased while the temperature increases. Furthermore, due to the increase the crystallinity of rutile RuO2 and decrease of hydrous RuO2 cause the diffusion of proton (H+) more difficult in electrodes, so the capacitance of electrode is decrease rapidly from 219 to 33 F/g. In second part. we control the ratio of Ru and Ta precursor. The result shows that while we increase the amount of Ta precursor, it makes the crack on the surface more clearly. When Ta is reach to 70 %, Ti substrate is exposed. From EDX analysis we can see that Ti signal also increase. From XPS analysis shows that the composition of RuO2 and RuO2 xH2O doesn’t change a lot. And the crystallinity of rutile RuO2 is decrease while we add more Ta in precusor. Although increasing the ratio of Ta2O5 can reduce the crystallinity of RuO2, it also reduce the capacitance (219 F/g at 70 % Ru decrease to 64 F/g)due to the Ta2O5’s low conductivity. Finally we combined RuO2 and EMI-TFSI、PMP-TFSI、PMP-FSI、PMP-TFSI/PC ionic liquid. The cyclic voltammetry curves show that the RuO2 electrode has obvious pseudo-capacitance effect in the above ionic liquid. And the potential window is also expanded compared to the conventional aqueous sulfuric acid solution. Among them, the EMI-TFSI ionic liquid has the best electrochemical performance, and its potential window reaches 3.5 V. The capacitance value reaches 49 mF/cm2, which is suitable as the electrolyte of RuO2 electrode.