Engineered electrolyte-structure synergy enabling high-performance symmetric supercapacitors based on porous carbon nanosheets derived from cassava peel

Carbon nanosheets having mesoporous texture with a surface area exceeding 1500 m 2 /g are synthesized from waste cassava peel. The elemental composition comprising carbon, oxygen, and nitrogen supplements the features of high porosity and surface area, altogether making the material highly preferable for energy storage applications. An electrolyte engineering strategy optimizing the concentration of 1 M H 2 SO 4 in 1 M Na 2 SO 4 further enhances the electrochemical energy storage performance of the carbon nanosheet electrode material. A symmetric supercapacitor with combined advantages of both electrode material and combination electrolyte marks a specific capacitance exceeding 280 F/g at a current density of 1 A/g, with reasonable retention even at 40 A/g. The device shows evident cyclic stability, retaining above 99% of its initial energy storage capability even after 10000 cycles. The strategy of valorizing waste cassava peel into highly porous carbon nanomaterial puts forward a sustainable solution for management of this agricultural waste as well as, an economically viable energy storage technology.