A review of cobalt monoxide and its composites for supercapacitors

Abstract Cobalt monoxide is a low–valence compound with a face–centered cubic structure and has been deemed as a promising electrode material for energy storage, such as batteries and supercapacitors (SC). In this work, the recent progress of CoO and its composites for SC application is briefly reviewed. The preparation methods for CoO are summarized at first. With the development of nanotechnologies, various CoO nanostructures are thus synthesized for SC, but most architectures grown on conductive substrates show higher specific capacitance than the corresponding power materials. If integrated with some typical guest materials, such as transition metal oxides, hydroxides, sulfides, and carbon materials (including carbon nanotubes, graphene and porous carbon) as well as conductive polymers, the CoO composites usually deliver promoted electrochemical performances. Thus, much attention is focused on the composites of CoO. An outlook for future work is finally put forward.