Highly porous honeycomb‐like activated carbon derived using cellulose pulp for symmetric supercapacitors

Summary Exploiting solid waste–derived activated carbon for energy storage has received widespread attention in recent times owing to their abundance, low cost, and good electrochemical properties. Herein, we present a resourceful conversion of cellulose pulp into honeycomb‐like activated carbon for use as capacitive‐type material in electrochemical supercapacitors. Initially, the cellulose pulp extracted from the milk packet, which was subjected to alkali treatment followed by carbonization, leads to the formation of numerous pores in the carbon skeleton. The as‐derived activated carbon demonstrated large specific surface area with dominant micropores. Utilizing the synergistic properties, the honeycomb‐like porous carbon exhibits superior electrochemical performance, including specific capacitance of 210 F/g at a current density of 1 A/g along with excellent cycling stability (96.5%) at high current density of 5 A/g, respectively. Following, a symmetric supercapacitor has been fabricated with carbon cloth as a current collector, which enables a maximum energy and power densities of 11.7 Wh/kg and 5312.5 W/kg, respectively. By serially connecting two symmetric supercapacitors, a digital watch was effectively illuminated for long‐time, demonstrating its potency for switching and proximity applications. Such value added conversion of solid waste–derived carbon material provides supreme paths for the development of high‐performance energy storage devices. Sustainable production of a capacitive carbon electrode manifesting notable performance attributed to its honeycomb‐like pore structure for symmetric supercapacitor.