Corn Husk Derived Activated Carbon/Siloxene Composite Electrodes based Symmetric Supercapacitor with High Energy Density and Wide Temperature Tolerance

Abstract In the present work, novel composite material comprising of corn husk derived activated carbon and siloxene nanosheets have been explored as new class of multicomponent electrode material for fabricating high energy density supercapacitors with wide temperature tolerance. The activated carbon obtained from corn husk (ACH–900) with high surface area and pore volume acts as an ideal framework for hosting siloxene nanosheets (S) that allows the overall siloxene–corn husk derived activated carbon (ACH–900/S) composite to deliver excellent electrochemical performance. The as‐prepared ACH–900/S composite electrode exhibited a high specific capacitance of 415 F g −1 at 0.25 A g −1 and retained 73.4 % of its initial capacitance even at a high current density of 30 A g −1 in 1 M Na 2 SO 4 electrolyte. In addition, the symmetric supercapacitor assembled with “acetonitrile/water‐in‐salt (AWIS)” electrolyte exhibited an energy density of 57.2 W h kg −1 at 338 W kg −1 with a cyclic stability of 92.8 % after 10000 cycles at 5 A g −1 current density. Besides, the fabricated ACH–900/S supercapacitor can operate over wide temperature range from 0 to 100 °C. This work opens up new frontiers to develop low‐cost safe supercapacitors with wide temperature tolerance and excellent electrochemical performance.