Recent Advances in Hybrid Supercapacitors

Research on electrochemical storage systems are persistently on the rise especially in the fields of supercapacitors and batteries. Several modifications are made continuously in supercapacitors with an intention to retain its excellent power density and to improve the inherently poor energy density. Initially, changes were made to these systems by introducing new electrodes, then new materials such as pseudocapacitors were launched and recently the formation of ‘hybrid’ systems. Three predominant supercapacitor hybrid systems are reported so far viz. symmetric, asymmetric, and supercapacitor-battery hybrid (SBH) systems. Each amendment in the hybrid systems revolutionized the electrochemical storage systems; however, the SBH systems dominated all the forms of hybrid devices. Several battery electrodes are introduced in hybrid cell along with a supercapacitor electrode and they exhibit excellent energy densities at high power densities. This chapter briefly reviews all forms of hybrid supercapacitors.