In-situ ZnO template preparation of coal tar pitch-based porous carbon-sheet microsphere for supercapacitor

Three-dimension (3D) porous carbon-sheet microspheres (PCSMs) are prepared through coating coal tar pitch on basic zinc carbonate microspheres followed by in situ ZnO template carbonization and KOH activation. The as-prepared PCSMs show microsphere morphology composed of petal-like carbon nanosheets, which have large specific area (1359.88–2059.43 m2 g−1) and multiscale pores (mainly micropores and mesopores). As the supercapacitor electrodes, the 3D PCSMs present a good electrochemical performance with a large specific capacitance of 313 F g−1 at 1 A g−1 and high rate capability of 81.9% capacitance retention when increasing the current density up to 50 A g−1 in a three-electrode system. In addition, the energy density can reach up to 18.79 Wh kg−1 at a high power density of 878.4 W kg−1 for PCSMs-0.2a symmetrical supercapcitor in 1 M Na2SO4 electrolyte.