Performance characteristics of several variants of interdigitated flow fields for flow battery applications

Abstract It has been reported in recent literature that interdigitated flow fields exhibit lesser pressure drop than serpentine flow fields for large area cells of vanadium redox flow batteries. In the present work, we report on a comprehensive characterization of the performance of cells using interdigitated flow fields. The study encompasses two cell sizes (nominal active area of 900 and 1500 cm2) and seven variants in terms of shape of the headers or channels and the number and orientation of the channels. Experimental investigations include pressure drop and polarization behavior under different flow conditions. It is shown that intedigitated flow fields suffer from flow mal-distribution when employed in cells of this size range with a correspondingly degraded electrochemical performance compared to cells with serpentine flow field. Improvement in the flow distribution by providing pillars in the headers is shown to improve electrochemical performance, although with a concomitant increase in pressure drop. The best interdigitated configuration among those studied has been found to match the discharge capacity of serpentine at high flow rates; however, the serpentine is found to be superior, in terms of both discharge capacity and pressure drop, at its best operating condition, which occurs at lower flow rates.