Densely stacked bubble-pillared graphene blocks for high volumetric performance supercapacitors

We report here the template-free synthesis of densely stacked bubble-pillared graphene blocks (DSBG) with abundant stable oxygen-containing functional groups as the electrode materials for supercapacitors through thermal treatment of graphene oxide. Owing to its dense, bubble-pillared structure and ultrahigh pseuclocapacitance from oxygen-containing functional groups, the resultant DSBG electrode possesses remarkable gravimetric and volumetric capacitance (352 F g(-1) and 739 F cm(-3)) in an aqueous electrolyte. More importantly, the assembled symmetric supercapacitor based on free-standing DSBG film exhibits superior energy density (23.4W h kg(-1) and 37.4W h L-1) in an aqueous electrolyte, well competitive with those of the previously reported carbon materials in aqueous electrolytes. The outstanding electrochemical performances may render such DSBG material a highly promising candidate for miniaturized and compact energy storage devices in the near future. (C) 2015 Elsevier B.V. All rights reserved.