Low temperature preparation of pore structure controllable graphene for high volumetric performance supercapacitors

High volumetric capacitance of supercapacitor is important and challenging for practical application in the energy storage devices. Herein, we develop a simple and effective approach to fabricate functionalized and pore structure controllable graphene via low temperature (∼170 °C) thermal treatment of graphite oxide with designed particle size. The as-obtained graphene with oxygen contents of 14.19 at.%, porous structure and a relative low pore volume (0.38 g cm−3), exhibits a promising material for the application in high volumetric performance supercapacitors. The prepared supercapacitor delivers a high volumetric capacitance of 226.9 F cm-3 at 0.5 A g−1 and achieves high rate capability (79% capacitance retention at 20 A g−1) in alkaline electrolyte. Moreover, the assembled supercapacitor in neutral electrolyte also exhibits a high volumetric energy density of 15.1 Wh L−1 as well as a high cycling stability with 94.2% retention after 9000 cycles. Therefore, this work will provide a new strategy for designing high volumetric capacitive performance of graphene for energy storage devices.