Robust Electrodes with Maximized Spatial Catalysis for Vanadium Redox Flow Batteries

Catalytic efficiency is a crucial index for electrodes in flow batteries, and tremendous efforts have been devoted to exploring catalysts with as many reaction zones as possible. Nevertheless, the space between the reaction sites, especially for interstitial space utilization, is usually ignored and challengeable to exploit owing to the balance between the catalytic efficiency and structural stability. Herein, a three-dimensional conducting network was constructed via a nitrogen-rich carbon film-bridged graphite felt framework (GF@N–C) to maximize its electrocatalytic effectiveness toward redox species. As the electrode, GF@N–C exhibits a superior rate constant and catalytic efficiency at 370 mA cm–2 and enables the vanadium redox flow battery to operate steadily at 200 mA cm–2 with an energy efficiency of 74.3% and a discharge specific capacity of 23 A h L–1. It is anticipated that the conducting network with optimized space utilization and catalysis will provide guidance for the design of high-efficiency electrodes and advance their development in flow batteries.