Numerical Simulation of Flow Field Structure of Vanadium Redox Flow Battery and its Optimization on Mass Transfer Performance

Abstract

The structural design of the flow channel of a redox flow battery directly affects ion transport efficiency, electrode overpotential, and stack performance during charge-discharge cycles. A tapered hierarchical interdigitated flow field design that has independent flow channel structures for different levels of flow was developed in this work. Especially, the secondary branch channels are the tapered type and the corresponding cross-sections are gradually reduced along the flow direction, which is beneficial for improving the flow rate at the end of channels and enhancing mass transfer. The performances of a vanadium redox flow battery with interdigitated flow field, hierarchical interdigitated flow field, and tapered hierarchical interdigitated flow field were evaluated through 3D numerical model. The results showed that at 240 mA/cm2 and 6 mL/s, the pump-based efficiency of the hierarchical interdigitated flow field increased by 4%-7% compared with the interdigitated flow field. Furthermore, the pump-based efficiency with tapered hierarchical interdigitated flow field increased by 1.6%-3% compared with the hierarchical interdigitated flow field. This indicates that the tapered hierarchical interdigitated flow field shows further advantages in redox flow battery applications.