Heteroatom-Rich Hierarchical Porous Biomass Carbon for Vanadium Redox Flow Batteries

Vanadium redox flow batteries (VRFBs) are safe and promising in large-scale energy storage but are restricted by tardy redox reaction rates of carbon felt (CF) electrodes. Biomass carbon has the potential to overcome the challenges due to adjustable pore structure, heteroatom doping, and economic benefits. Herein, a bamboo-derived carbon-modified CF with O, N codoping and hierarchical porous (ABC-N-CF) was fabricated via selective removal of hemicelluloses and lignin and plasma post-treatment. The hierarchical porous structure of biomass carbon is conducive to an increase in edge defects and electrolyte infiltration. The optimal O, N codoped configuration was analyzed by density functional theory, revealing the reason for the carboxyl ortho-graphitic nitrogen codoped biomass carbon achieving rapid charge migration for the VO2+/VO2+ redox couples. Furthermore, a single battery assembled with ABC-N-CF remained only with a 0.01 Ω·h–1 variation of Rct at 120 mA·cm–2 over 1000 cycles. We believe that this study not only provides a promising strategy for high-performance biomass carbon-modified electrodes in VRFBs but also offers an effective method of realizing biomass conversion into energy storage materials for sustainable utilization.