The mass transfer performance is unclear to limit the development of organic flow battery, which is regarded as the emerging electrochemical energy storage technology. The mass transfer behaviors in the electrode are influenced by the flow fields, which is indispensable. A three-dimensional and steady numerical model of the organic flow battery is established and the results are verified by the experiments data. The battery performance and mass transfer behaviors are analyzed under different flow field for the charge/discharge processes based on this model. Compared with other flow fields, the interdigital flow field can achieve the best charge-discharge performance, which is mainly due to the improvement distribution uniformity of active species. The average concentration of the interdigital flow field is 45.1% higher that of the conventional flow field. The effects of the flow rates and initial concentration of electrolyte on the battery performance are investigated, and the results indicate that appropriate inlet flow rate can lead to the highest net discharge powers and power-based efficiency of the flow battery. Although the increasing of the initial concentration can improve the battery performance, the improvement is too slight when the concentration is high enough, which can lead to the waste of active species.

The all-vanadium redox flow battery (VRFB) was regarded as one of the most potential technologies for large-scale energy storage due to its environmentally friendliness, safety and design flexibility. The flow field design and mass transfer performance in the porous electrodes were some of the main factors to influence the battery performance. A novel biomimetic lung-shaped flow field was designed, and the battery performance was compared with the serpentine flow field by numerical simulation analysis. The results showed that the charging voltage of the VRFB was reduced by about 5.34% when SOC = 0.9 compared with the serpentine flow field. On the other hand, the discharging voltage was promoted by about 9.77% when SOC = 0.1 compared with the serpentine flow field. The battery performance of the VRFB is obviously due to the enhancement of the mass transfer performance. The uniformity factor was promoted by 35.6% by the lung-shaped flow field when SOC = 0.1, which can reduce the polarization loss. The average concentration of the active ions was increased by about 18% by the lung-shaped biomimetic flow field, which was of significance to the electrochemical reaction. The design of the lung-shaped flow field can contribute to the application of the VRFB.