A High Current Density and Long Cycle Life Iron Chromium Redox Flow Battery Electrolyte

The electrolyte in the flow battery is the carrier of energy storage, however, there are few studies on electrolyte for iron-chromium redox flow batteries (ICRFB). The low utilization rate and rapid capacity decay of iron-chromium redox flow battery electrolyte have always been a challenging problem. Herein, the effect of Fe/Cr molar ratio, and concentration of HCl on the performance of ICRFBs at high current density (140 mA cm-2) are investigated. The average energy efficiency of the optimum electrolyte (1.25 M FeCl2, 1.50 M CrCl3, in 3.0 M HCl) is 5.99% higher in the first 20 cycles, and the discharge capacity is 15.72% higher in the first cycle than the commercial electrolyte (1.0 M FeCl2, 1.0 M CrCl3 in 3.0 M HCl). This electrolyte also shows a longer cycle life. In addition, the COMSOL simulation on the concentration change of electrolyte in ICRFB is proposed, the effect of physical properties on the electrolyte is further explained. Through the simulation and analysis of this complex system, researchers can better understand and optimize the performance of flow battery systems, especially when considering various challenges and constraints that might be encountered in practical applications. This work effectively saves the cost of ICRFB and further provides data support for their engineering applications.