▎ 摘　　要

By using oxalic acid (OA) as template and reducer, a novel approach is developed to prepare reduced graphene oxide films with capsular pores (C-rGOFs) under a hydrothermal condition. The effect of preparation conditions including concentrations of OA and reaction temperatures on the films' structure and capacitive performances has been systematically investigated. The optimal C-rGOF shows uniform capsule-like morphology and exhibits a density of 1.18 g cm(-3). Tested by using a two-electrode system, the optimal film shows gravimetric specific capacitance of about 234.9 F g(-1) and volumetric specific capacitance of 277.2 F cm(-3). Additionally, the optimal film which shows good rate capability can retain 63.9% of initial capacitance at high scan rate of 1.0 V s(-1), which is much higher than that of the controlling reduced graphene oxide film (rGOF, 180.5 F g(-1), 373.6 F cm(-3) and retain only 45.0% of its initial capacitance at 1.0 V s(-1)). The cells assembled by the optimal C-rGOF exhibit maximum energy density of 7.5 Wh kg(-1), power density of 16.9 kW kg(-1), and excellent cycling stability with 91.2% capacitance retention after 21 000 cycles. It is believed that this method can be developed as a useful strategy to prepare rGO-based materials for energy storage applications.