B, N, and O Co‐Doped Nanoporous Activated Carbon With High Surface Area and Hierarchical Porous Structure for Enhanced Li‐Ion Battery and Supercapacitor Performance

ABSTRACT Nanoporous carbon materials with tunable physicochemical characteristics, such as high surface area, promising conductivity, and structural tunability, are attractive candidates for the design of high‐efficiency energy storage devices. In this work, B, N, and O co‐doped nanoporous carbon with high surface area and hierarchical pore structure has been synthesized through solid‐state activation of a mixture of boric acid, sucrose, and aminoguanidine using potassium citrate as the mild activating agent. The incorporation of B, N, and O not only introduces surface functionalities but also tailors the pore structure and surface area. The symmetric supercapacitor displayed an energy/power density of 34.32 Wh kg ⁻¹ /599.99 W kg ⁻¹ , respectively, with 100% cyclability up to 10,000 cycles. Further, when employed as anodes for lithium‐ion batteries (LIBs), the material exhibits an exceptional specific capacity of 1606.3/1415.2 mA h g ⁻¹ at 0.05/0.1 A g ⁻¹ , which is an eight‐fold increase in the capacity compared to bare nanoporous carbon. Further, the ex situ SEM, TEM, EIS, and XRD measurements were carried out to analyze the material's structural changes post LIB cycling.