Dual-template endowing N, O co-doped hierarchically porous carbon from potassium citrate with high capacitance and rate capability for supercapacitors

Abstract

Engineering hierarchically porous architecture with large ion accessible surface area and abundant pseudocapacitive sites is highly desired for carbon materials to achieve high energy density and high rate capability in supercapacitors. In particular, designing a facile strategy for one-step synthesis of such carbon materials with multiple synergistic effects is full of challenges. Herein, we develop a one-pot strategy with dual template to synthesize N, O co-doped hierarchically porous carbon nanosheets (NOPC). The optimal NOPC possesses a large surface area (2557 m2 g−1) with hierarchical pore network and high pore volume (1.6 cm3 g−1), as well as abundant pseudocapacitive active species. Consequently, in the three-electrode cell, the resultant NOPC electrodes produce an outstanding specific capacitance of 527F g−1 at a current density of 1 A g−1, and a high rate capability of 246F g−1 even up to 200 A g−1. In addition, the assembled symmetric supercapacitors yield a high energy density of 14.5 Wh kg−1 at 250 W kg−1, and remain 8.5 Wh kg−1 even the power density as high as 25 kW kg−1. Such performance can outperform those of most recently reported carbon-based materials. In view of the facile synthetic route, available raw material, and encouraging performance, this work paves a new prospect to construct advanced carbon-based materials toward practical energy-related applications.