Graphene Oxide/MnO₂ Composites Synthesized by "Quenching" for Supercapacitors with High Capacitance

Abstract

Graphene Oxide (GO)/manganese oxide (MnO 2 ) composites with different feeding ratio are synthesized by a simple and economic soft chemical route in a water-isopropyl alcohol under different cooling method. The SEM results show that MnO 2 nanoparticle with smaller size (8nm) homogeneously coats on the surfaces of graphene oxide under quick ice quenching, and the better electrochemical properties is obtained. The composites with feeding ratio 1:9 have maximum capacitance value, because of agglomerate induced by too much MnO 2 . The specific capacitances calculated by galvanostatic charge/discharge curve were 312.87 F/g by ice water quenching and 253.12 F/g by reflux cooling to room temperature. The GO/MnO 2 electrode retained about 85.12% (with quick ice quenching) and 88.16% (with reflux cooling) of initial capacitance after 1000 cycles, respectively.