Effective splitting of serpentine flow field for applications in large-scale flow batteries

Abstract

Industrial flow battery stacks require large area cells for which flow fields are essential to ensure uniform distribution of the electrolyte. Serpentine flow fields have proven to be ideal from a flow distribution point of view but suffer from high pressure drop. In the present work, a new flip-flop directional split serpentine flow field is proposed to reduce pressure drop by splitting the flow field into segments and improving electrochemical performance by quick evacuation of reaction products. Comparative experimental studies with a single serpentine and two other split serpentine flow fields confirm the effectiveness of the new flow field. An improvement of around 12% in discharge energy and 3% in round-trip efficiency has been observed with flip-flop at current densities of 90 mA cm−2 and 120 mA cm−2 over a single serpentine flow field for a cell active area of 900 cm2. Calibrated computational fluid dynamics simulations confirm that the proposed flow field ensures good distribution and quick evacuation of product species. Scalability of the new flow field to large cell size has been demonstrated by obtaining good performance data on a cell of 2200 cm2 active area, which is among the largest reported in the literature.