Numerical Investigation of Channel-to-rib Ratio and Serpentine Flow Field Design on the Performance of Vanadium Redox Flow Batteries

This study presents a numerical simulation to investigate the effects of channel-to-rib ratio and serpentine flow field design on the performance of vanadium redox flow batteries. The analysis consists of two stages: first, three different channel-to-rib width ratios (Wc:Wr = 1:2, 1:1, and 2:1) are compared in terms of pressure drop, species concentration distribution, and charge–discharge behavior. Based on the best-performing ratio (1:2), the second stage further examines the effect of serpentine flow fields with varying inlet numbers, 1-inlet, 2-inlet, and 4-inlet serpentine configurations, on battery performance. Simulations are conducted under fixed operating conditions of 80 mA/cm2 current density and 60 ml/min electrolyte flow rate. Key metrics such as pressure drop, concentration field, initial voltage, capacity, and three efficiency indicators (Voltage efficiency, Coulombic efficiency, and Energy efficiency) are analyzed. Experimental results reveal that best performance across all metrics, with a Coulombic efficiency of 98.42%, voltage efficiency of 90.64%, and energy efficiency of 89.21%, were exhibited by the Wc:Wr = 1:2 structure. The 1:1 configuration ranks second (Coulombic efficiency of 97.82%, voltage efficiency of 89.91%, and energy efficiency of 87.96%, respectively), followed by the 2:1 configuration (Coulombic efficiency of 97.60%, voltage efficiency of 88.71%, and energy efficiency of 86.58%). Regarding inlet configurations, the 1-inlet serpentine provides the highest capacity (1086.65 / 1063.96 mAh) with the lowest polarization loss, while the 2-inlet design achieves the highest energy efficiency (89.21%) and Coulombic efficiency (98.42%). In summary, the 1-inlet and 2-inlet serpentine designs are respectively suitable for capacity-oriented and efficiency-focused applications, offering valuable insights for optimizing VRFB flow field design.