A Split Convection-Enhanced Flow Field for Stack-Scale Redox Flow Batteries

Flow fields in redox flow batteries are pattern designed to achieve a maximized uniformity of electrolyte distributions with a minimum pump work. It is challenging to scale up a lab-scale flow field to a stack level due to the lack of effective scale-up methods. In this work, a split strategy by dividing the active area into subzones is proposed to scale up a high-performing convection-enhanced flow field. Two split patterns, which have large and small aspect ratios in terms of different flow channel orientations, are designed and evaluated under varying scale-up factors. It is revealed that the subzone flow field with a large aspect ratio reduces the convection distance in both channels and electrodes, thereby decreasing the system pressure drop while maintaining the enhanced mass transport. In the meanwhile, the bifurcated distribution/collection channels ensure the uniform electrolyte distribution among subzones and demonstrate good scalability. As a result, compared to the conventional flow field with a single channel, the application of the split pattern comprising 4 subzones to a 1142.4cm(2) vanadium redox flow battery enables a 91.7 % reduction in pump loss and improves the system efficiency from 75.7 % to 84.8 % at 0.8 mL min(-1) cm(-2) and 100 mA cm(-2). This work presents that the split strategy offers a promising solution for scaling-up flow fields which paves the way for further commercialization of stack-scale flow batteries.