Graphite Felt Electrode Modified by Quaternary Ammonium for Vanadium Redox Flow Battery with an Ultra-Long Cycle Life

Vanadium redox flow batteries (VRFBs) are one of the most attractive devices for grid-scale energy storage due to their advantages of high safety, flexible assembly, and electrolyte-class recycling. However, the conventional graphite felt electrodes usually possess inferior electrocatalytic activity for vanadium ion redox reactions, vastly limiting the rate and lifespans of VRFBs. Herein, we demonstrate a high-rate and ultra-stable vanadium redox flow battery based on quaternary ammonium salt-modified graphite felt electrodes. At a high current density of 200 mA cm−2, the constructed VRFB exhibited a superior cycling life of up to 1000 cycles. This work affords a straightforward approach for developing efficient, environmentally friendly, and low-cost graphite felt electrodes for ultra-stable and high-rate VRFBs.