Novel Interdigitated Flow Field with a Separated Inlet and Outlet for the Vanadium Redox Flow Battery

The vanadium redox flow battery (VRFB) is considered as a promising energy storage technology to solve the environmental problems of global warming. The optimizations should be carried out before the large-scale commercialization of the VRFB, and the flow field greatly affects the battery performance. In the paper, a two-sides interdigitated flow field (IFF) is designed for improving the mass transfer behaviors, and a three-dimensional numerical model is established to predict the charge–discharge process of the VRFB. The charge–discharge voltage, overpotential, concentration distribution, and uniformity factors are analyzed to evaluate the battery performance of different flow field designs (case 1, the conventional IFF; case 2, the two-sided IFF; and case 3, the two-sided IFF with a high contacting area). In comparison to cases 1 and 2, the VRFB with the case 3 design possesses the highest discharge voltage and the lowest charge voltage. For the distribution uniformity factor of V2+, case 2 is 5.5% higher than case 1 and case 3 is 17% higher than case 1. The two-sided IFF outputs the highest net power. Furthermore, case 3 can acquire 85.6% system efficiency, while the efficiency of case 1 is 84.5%, which shows that the two-sided IFF is more suitable for the large-scale VRFB.