Electrochemical capacitance of mesoporous tungsten oxynitride in aqueous electrolytes

• Published in: Journal of power sources 2012-12, Vol.220, p.298-305
• Main Authors: Kartachova, Olga, Glushenkov, Alexey M., Chen, Yanhui, Zhang, Hongzhou, Dai, Xiujuan J., Chen, Ying
• Format: Article
• Language: English
• Subjects: Applied sciences; Aqueous electrolytes; Capacitors. Resistors. Filters; Cyclic stability; Electrical engineering. Electrical power engineering; Exact sciences and technology; Oxynitrides; Pseudocapacitance; Supercapacitors; Various equipment and components
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2012.07.132

Transition metal nitrides and oxynitrides are promising candidates for the application in electrodes of supercapacitors. In this manuscript characterization of tungsten oxynitride and its electrochemical properties in a range of aqueous electrolytes (1 M H2SO4, 1 M KOH, 3 M KCl, 3 M NaCl, 1 M LiCl and 1 M CaCl2) are presented. The electrochemical behavior of tungsten oxynitride depends strongly on the type of cation present in the electrolyte, and the highest capacitance value of 85 F g−1 is measured in 1 M H2SO4. Cyclic stability in the acid, neutral and alkaline electrolytes is evaluated, and the highest stability is observed in 1 M KOH electrolyte. Possible charge–discharge mechanisms are discussed, and the contribution of a pseudocapacitive mechanism in addition to the electric double-layer formation is proposed. ▸ Tungsten oxynitride W0.75(N,O) is evaluated as an electrode material for supercapacitors. ▸ The electrochemical properties of W0.75(N,O) are studied in aqueous electrolytes. ▸ Maximum capacitance is observed in H2SO4 electrolyte and maximum stability is found in KOH electrolyte. ▸ The contribution of a pseudocapacitive charge storage mechanism is proposed.