MnO2/carbon nanowalls composite electrode for supercapacitor application

Amorphous MnO2/carbon nanowalls composite films are developed for the supercapacitor applications. Synthesis of carbon nanowalls template is performed by plasma-enhanced chemical vapor deposition in a CO/H2 microwave discharge system. A well dispersion of amorphous MnO2 domains throughout carbon nanowalls template is obtained by potentiostatic anodic deposition technique. Carbon nanowalls enable to improve the capacitive behavior and rate capability of MnO2, a specific capacitance of 851 F g−1 at a current density of 1 mA cm−2 and charge transfer resistance of 1.02 Ω are obtained. MnO2/carbon nanowalls composite film exhibits energy density of 118 wh kg−1, power density of 783 wh kg−1, and capacitance retention of 92% after long cycle life of 2000 cycles by charging and discharging at 3 mA cm−2. The high density of atomic scale graphitic edges and large surface area of carbon nanowalls in conjunction with the presence of amorphous MnO2 domains facilitate rapid electron and ion transport and hence offering the potential of the improved capacitive behavior.