Enhanced Supercapacitance Performance of Hierarchically Porous Carbon Obtained from Terminalia bellirica (Barro) Seed Stone

Biomass carbons are promising candidates for energy storage applications due to their large surface areas, hierarchical pore structures, well-defined pore dimensions, and tunable porosity. Here, we report the production of porous carbon materials from Terminalia bellirica (Barro) seeds involving zinc chloride activation at different impregnation ratios (1:1–1:3) and carbonization temperatures (700–900 °C), and their supercapacitive performances in 1 M sulfuric acid in three-electrode and two-electrode systems. The material carbonized at 700 °C at an impregnation ratio of 1:3 exhibited a high specific surface area of 2301 m 2 ·g –1 and a large pore volume of 1.887 cm 3 ·g –1 . Electrochemical analyses revealed an electrical double-layer charge storage mechanism, and the electrode achieved a maximum specific capacitance of 365.4 F·g –1 at 1 A·g –1 with an excellent capacitance retention of 66.0% even at 50 A·g –1 . The symmetric supercapacitor cell assembled using this material delivered an energy density of 7.1 W·h kg –1 at a power density of 600 W·kg –1 retaining 98.2% cycle life after 10,000 charge/discharge cycles. These results indicate that there is great potential in using Barro seed as a sustainable carbon source for the fabrication of high surface area activated carbons for energy storage supercapacitor applications.