Inherent Oxygen‐ and Nitrogen‐Doped Porous Carbon Derived from Biomass of Tamarind Leaf for High‐Performance Supercapacitor Application

Herein, oxygen‐ and nitrogen‐doped porous carbon material using tamarind leaves via simple chemical activation and carbonization process are presented. Subsequently, the as‐obtained material has not only exhibited a 3D hierarchical honeycomb‐like framework but equally reveals a high specific surface area of 1212 m 2 g −1 . In favor of the synergistic relationship between the tailored pore architecture and surface enriched heteroatoms, the electrochemical performances are evaluated in a three‐electrode system and by constructing a symmetric solid‐state device. A specific capacitance of 370, 293, and 193 F g −1 at 1 A g −1 is achieved in a three‐electrode system using H 2 SO 4 , Na 2 SO 4 , and KOH electrolytes, respectively, with electrochemical double‐layer capacitor (EDLC) and pseudocapacitive contributions. Moreover, a high energy density of 36.96 Wh kg −1 at 1 A g −1 and a high power density of 4.49 kW kg −1 at 10 A g −1 are obtained from the assembled solid‐state device along with excellent capacitive retention of 93% after 5000 cycles.