▎ 摘　　要

For aqueous supercapacitors, the voltage window and relatively low energy density have always been the main concerns hindering its development and application. Although the operational voltage window is determined by the intrinsic electrochemical stability of water (1.23 V), such an impediment could be overcome by taking advantage of the additional overpotential of the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Herein, vertical graphene nanosheet arrays (VGs) were in situ grown on carbon cloth substrate (CC-VG) via a plasma enhanced chemical vapor deposition (PECVD) method, and a flexible supercapacitor cathode material CC-VG/Na0.5MnO2 was subsequently prepared by electrodeposition and electrochemical oxidation. It is interesting to find that the electrode voltage window for CC-VG/Na0.5MnO2 can be extended to 0-1.3 V with significantly increased specific capacitance up to 525 F/g at 2 A/g benefitting from the presence of VGs and the high Na+ content that increased overpotential of OER by the Na+ deintercalation/intercalation, which shed new lights on developing widen-voltage aqueous supercapacitors with high energy density.