Biochar for supercapacitor electrodes: Mechanisms in aqueous electrolytes

The utilization of biomass materials that contain abundant carbon–oxygen/nitrogen functional groups as precursors for the synthesis of carbon materials presents a promising approach for energy storage and conversion applications. Porous carbon materials derived from biomass are commonly employed as electric‐double‐layer capacitors in aqueous electrolytes. However, there is a lack of detailed discussion and clarification regarding the kinetics analysis and energy storage mechanisms associated with these materials. This study focuses on the modification of starch powders through the KOH activation process, resulting in the production of porous carbon with tunable nitrogen/oxygen functional groups. The kinetics and energy storage mechanism of this particular material in both acid and alkaline aqueous electrolytes are investigated using in situ attenuated total reflectance‐infrared in a three‐electrode configuration. N, O‐co‐doped biomass carbon electrode material was successfully prepared by using potato as precursor and urea as nitrogen source, which exhibits high specific capacitance and extraordinarily excellent long‐life stability of 50,000 cycles. Importantly, in situ attenuated total reflectance infrared analysis successfully clarified the charge storage mechanism of biomass carbon electrode material under acid and alkaline electrolytes, and explored the storage capacity of supercapacitors from the concentration of functional groups and the bonding and breaking of molecules at the molecular level.