Metal oxides in supercapacitors

Abstract

Abstract Metal oxides are generally considered prime candidates for use as electrode materials in supercapacitors, because a wide variety of oxidation states is possible for redox charge transfer. This chapter introduces metal oxides as electrode materials in supercapacitors. It starts by providing some introductory background on supercapacitors, and then presents the fundamental principles, characteristics, and electrolytes of supercapacitors. Three types of capacitors are discussed: electric double-layer capacitors, pseudocapacitors, and hybrid supercapacitors. Next, preparation methods and electrochemical performance of metal oxides (such as specific capacity, cycling performance, rate capability, energy density, and power density) are explained. Finally, a full discussion of structure, topography, and electrical conductivity is included to show their relationship with electrochemical performance of metal oxides and supercapacitors. The possible course of future research is also discussed.