Hybrid supercapacitors based on intercalation compounds as positive electrodes

In this paper a short introduction to the latest development on hybrid supercapacitors based on intercalation compounds is presented, and the up-to-date research results of our laboratory on the influence of aqueous electrolytes, electrode materials (activated carbons, MnO₂, V ₂O₅, LiCoO₂, LiMn₂O₄, Na_xMnO₂ and K_xMnO₂) and some supercapacitors are mainly expounded. It should be noted that the hybrid supercapacitors based on intercalation compounds containing alkali metal elements presents great promise for applications due to the following reasons : (1) the electrolytes are different from those of other supercapacitors and they do not need to provide anions and cations for positive and negative electrodes, (2) the electrode materials have high capacitance, high power density and excellent cycling behavior. For example, in the case of amorphous nano MnO ₂, after 23 000 full cycles, the capacitance retention is above 94%. As to the hybrid supercapacitor of AC//LiMn₂O₄ nanorod, its energy density based on the active electrode materials can be above 50Wh/kg with excellent power characteristics. Finally, some future directions are pointed out especially some non-carbon based negative electrode materials with capacitive and redox behaviors.