Impact of Activation Conditions on the Electrochemical Performance of Rice Straw Biochar for Supercapacitor...

Biochar, derived from agricultural waste, has gained significant attention as a sustainable material for energy storage applications due to its high surface area, tunable porosity, and environmental benefits. This study investigates the electrochemical performance of rice straw biochar (RSBC) as an electrode material, with a focus on the effects of activation temperature, activation ratio, and activation time. Among the prepared samples, RSBC-2, activated at 800 °C with a 1:2 KOH ratio for 0.5 h, exhibited the best electrochemical performance. Characterization of RSBC and RSBC-2 showed significant improvements in surface area and pore structure. Specifically, the BET surface area of RSBC-2 increased to 939.40 m² g^-1, with a reduced average pore size of 2.27 nm. Electrochemical testing revealed that RSBC-2 achieved specific capacitances of 296, 281, 272, 260, and 240 F g^-1 at current densities of 0.2, 0.5, 1, 2, and 5 A g^-1, respectively, with a capacity retention rate of 81%. The improved electrochemical performance of RSBC-2 is attributed to its larger surface area and enhanced pore structure, which facilitate better charge storage and overall electrochemical behavior, making it a promising candidate for energy storage applications.