Graphene based architectures for electrochemical capacitors

Graphene has attracted intense attention in electrochemical capacitors (ECs) as electrode material due to its excellent electronic, mechanical and thermal properties as well as its ultrahigh specific surface area. Considering the electrochemical performance of an EC is largely determined by electrode architectures, this review particularly focus on recent progress on designing and controlling the architectures of graphene based electrodes. After briefly introducing the energy storage mechanisms of ECs and the effects of pore sizes and pore size distribution on capacitance, we highlight the development and challenges for one to three dimensional graphene electrodes, their respective advantages, and corresponding electrochemical performance including specific capacitance, energy density, power density, rate capability and cyclic stability. This review also highlights the effects of introducing other electro-active materials such as carbon nanotubes, conducting polymers and metal oxides on the electrochemical performance of one to three dimensional graphene hybrid electrodes.