Fenton Reaction Doubled Biomass Carbon Activation Efficiency for High‐Performance Supercapacitors

Abstract The huge consumption of alkali during biomass‐derived porous carbon production leads to pollution and high carbon‐emission. This study employs the concept of Fenton chemistry to achieve hierarchical porous biomass carbon materials with a remarkably high specific surface area of 3440 m 2 g −1 with double activation efficiency compared to traditional activation process. The optimized carbon electrode demonstrates exceptional specific capacitance of 425.2 F g −1 at a current density of 0.1 A g −1 and great rate performance (286.1 F g −1 at 100 A g −1 ) in 6 m KOH electrolyte. The enabled supercapacitor demonstrates remarkable cycling stability, retaining up to 99.74% of its initial capacitance after undergoing 20 000 charge–discharge cycles. In addition, the electrolyte ion distribution in different pore structures is simulated using Molecular Dynamics, which confirms that the structure is conducive to the rapid diffusion of ions, thus matching the excellent electrochemical properties. The assembled symmetric supercapacitors achieve a maximum energy density of 42.1 Wh kg −1 (12.1 Wh kg −1 based on cell stack mass) in TEABF 4 /AN electrolyte. This work presents an effective technique for the formation of porous structures from biomass precursors. The novel methodology can be applied to many other similar systems for energy storage and beyond.