Metal oxide nanomaterials for pseudocapacitors

With the rapid development of economy, the consumption of fossil fuels, and the increasing environment pollution, there is in urgent need of seeking clean and renewable energy sources, as well as highly efficient and low-cost energy storage technologies. Concerning electrochemically active materials, transition metal oxides (TMOs) are regarded as the most promising candidates for the next generation SCs and have been widely reported. Therefore, in this review, we mainly pay attention to TMOs with excellent electrochemical performance. This review is divided into four parts: (a) the background including energy storage mechanisms and electrochemical characterizations of SCs; (b) various kinds of TMOs for SCs are analyzed in detail involved in crystal structure, conductivity, and energy storage mechanism; (c) hybridizations with other materials to improve the electrochemical performance of TMOs are summarized and discussed; (d) a perspective and short remarks about the development and design of TMOs for superior performance SCs are shown.