Effect of variable cross-section electrode on the battery performance of all-vanadium redox flow battery

The global warming can be relieved by the application of the renewable energy, which should be supported by the large-scale energy storage such as the vanadium redox flow battery (VRFB). The charge-discharge reactions mainly take place in the porous electrodes, which can influence the battery performance. In the paper, a variable cross-section electrode with interdigital flow field was proposed to enhance the mass transfer in the porous electrode. The charge-discharge voltage, overpotential, concentration distribution and uniformity factors are predicted by a 3-D numerical model to evaluate the battery performance of different electrodes (the Conventional electrode; Variable coss-section electrode #1: the variable coss-section electrode with the interdigital flow field distributed on one side; Variable coss-section electrode #2: the variable coss-section electrode with the interdigital flow field distributed on both sides). The discharging voltage of the variable coss-section electrode #2 was 1.25% higher than that of the variable coss-section electrode #1. The uniformity factor of the variable coss-section electrode #1 and the variable coss-section electrode #2 was 14.24% and 19.56% higher than that of the conventional electrode, respectively. Considering the machining process and promotion of the battery performance, the variable coss-section electrode#1 was the best design of the three battery models mentioned in this article.