Pencil Peel Derived Mixed Phase Activated Carbon and Metal-Organic Framework Derived Cobalt-Tungsten Oxide for High-Performance Hybrid Supercapacitors

Abstract In this work, pencil peel is used to derive the mix phase activated carbon at different temperatures viz 700, 800, and 900 °C for hybrid supercapacitor applications. The derived carbon is showing the highest specific surface area for P-800 (Pencil peel@ 800 °C) sample and exhibits the graphitic and amorphous phase whose fraction can be controlled with pyrolysis temperature. Therefore, the as-prepared P-800 electrode shows the high specific capacitance of 553 F/g at a current density of 1 A/g. On the other hand, metal-organic framework (MOF) derived Cobalt-Tungsten oxide composites (Co3O4/WO3) has been synthesized which shows a much higher specific capacitance value (544 F/g at 2 A/g) in the negative potential window. Therefore, an asymmetrical supercapacitor device has been assembled with P-800 as positive and Co3O4/WO3 composites as a negative electrode in aqueous 1 M H2SO4 (Sulfuric acid) electrolyte that delivers higher energy and power density in comparison to their symmetrical supercapacitor counterparts.