Effects of the Intrinsic Structures of Graphite Felt and Carbon Cloth on the Working Condition of Iron-Chromium Redox Flow Batteries

The design parameters of large-scale iron-chromium redox flow batteries (ICRFB) encompass a wide range of internal and external operational conditions, including electrodes, membranes, flow rate, and temperature, among others. Among these factors, the intrinsic structures of graphite felt (GF) and carbon cloth (CC) play a pivotal role in determining the overall working conditions of ICRFBs. This study systematically investigates the multifaceted relationship between the intrinsic structure of the GF and CC and their impact on the operational performance of ICRFBs. The fundamental difference between the two types of electrodes lies in the intrinsic structure space available in them for electrolyte penetration. A systematic analysis of the structure–activity relation between the electrodes and the initial internal resistance, as well as the operating temperature of the cell, was performed. Additionally, the influence of the electrode structure on critical parameters, including the flow rate, membrane selection (Nafion 212 and Nafion 115), and performance of electrodeposition catalysts (bismuth and indium), is examined in detail. Under varying operating conditions, the intrinsic structures of GF and CC turn out to be a crucial factor, providing a robust basis for electrode selection and performance optimization in large-scale ICRFB systems.