Carbon felt electrode modified by lotus seed shells for high-performance vanadium redox flow battery

Vanadium redox flow batteries (VRFBs) have attracted considerable attentions for their promising applications as large-scale energy storage devices. However, the widespread implementation of VRFBs is still hindered by the severe overpotentials of redox reactions, due to the poor electrochemical activities of conventional carbon felt (CF) electrodes. Herein, we present the fabrication of biomass lotus seed shells-modified CF (Bio-CF) electrode, which exhibits remarkable electrocatalytic effects on both the V2+/V3+ and VO2+/VO2+ redox reactions. The influences of auxiliary sucrose concentration and pyrolysis temperature were investigated to optimize the Bio-CF electrodes. Meanwhile, molecular dynamic simulations were employed to verify the experimental data. Furthermore, high performance VRFBs were achieved with the optimized Bio-CF electrode, affording high energy efficiency (83.14 %) and outstanding cycling stability under a current density of 100 mA cm−2. It is believed that the strategy to improve electrochemical performance of CF modified by cost-effective biomass materials provides a promising route for developing high performance VRFBs.