Scale-up of high power density redox flow batteries by introducing interdigitated flow fields

Lab-scale redox flow batteries (RFBs) employing thinner electrodes have achieved outstandingly high power densities. When these high-performance thinner electrodes are scaled up to larger sizes required for kW-scale stacks, adding interdigitated flow fields is a simple solution in maintaining low pressure drops. A 3-D model of a half-battery with an active area of 900 cm2 was developed to explore the design rules of flow fields. Optimizing the number and size of channels is essentially striking a balance between the pressure drop and the electrolyte velocity in the electrode, which have important effects on the pumping loss and mass transport loss respectively. In addition to the magnitude of the average velocity, the uniformity of velocity distribution should also be paid attention to in designing flow fields, which is determined by the ratio of flow resistance in the electrode to that in the channels. Acceptably thicker channels are recommended to improve uniformity of velocity distribution.