Numerical modeling of a convection-enhanced flow field for high-performance redox flow batteries

Designing flow fields with enhanced convection is crucial to achieve a uniform electrolyte distribution and thus to improve the battery performance. In this work, we numerically model a new type of convection-enhanced flow field, which is designed by repatterning the flow path of serpentine flow field to strengthen the mass transport between neighboring channels. Key geometric parameters and flowing patterns are investigated. It is revealed that decreasing the channel fraction and increasing the channel number result in a more uniform reactants distribution, but lead to an obvious increase of pumping work. Additionally, by tailoring rotary methods with two criteria of the path number and path sequence, seven novel patterns with rationally designed convection-enhanced flow path are proposed. Results show that when the number of paths is five and the outflow path is in the middle, the most uniform reactants distribution and the lowest pressure drop between inlet and outlet can be achieved. More impressively, the vanadium redox flow battery with the optimized flow field achieves a higher pump-based voltage efficiency than that with the serpentine flow field (87.1% vs. 82.8%) at 150 mA cm−2, indicating that the convection-enhanced pattern shows great promise for the application in high-performance flow batteries.