Electrochemical Properties of Metal Hydroxides

The electrochemical capacitor has received remarkable attention due to its bridging performance for the power/energy interval between conventional capacitors and batteries/fuel cells. The electrochemical behavior of capacitors is mainly influenced by using electrode materials. One of the promising pseudocapacitive materials is metal hydroxide, whose electrochemical performances originated from reversible Faradaic reactions between the electrode and electrolyte interface. It is necessary to use advanced pseudocapacitive materials to manufacture supercapacitors to solve their problem of lower energy density (E) compared to lithium batteries. Different strategies, such as doping, various synthesis methods, fabrication of composites, and utilization of conductive substrates, have been introduced. This chapter represents investigations on pseudocapacitive electrode materials, essentially transition metal hydroxides. Some published reports about applications of metal hydroxides as pseudocapacitive electrode materials with their different structures and composites are summarized in this chapter. Some strategies to improve the electrochemical performance of transition metal hydroxides are mentioned.