Mass transfer enhancement in electrode and battery performance optimization of all-vanadium flow based on channel section reconstruction

Abstract

The all-vanadium redox flow battery(VRFB) is one of the most commercially developed energy storage technologies due to the high efficiency, long cycle life, flexible design. The novel battery performance optimization based on the channel section reconstruction is proposed, which can enhance the electrolyte penetration and promote the species distribution. A 3-D numerical model for VRFB is built to investigate the mass transfer behavior and battery performance with different channel sections. The results show that the mass transfer behaviors in the porous electrode and battery performance are influenced by the channel section, which can influence the Reynolds number and hydromechanics. The VRFB with the semicircular channel section design needs the lowest charging voltage and exhibits highest discharge voltage, which is mainly attributed to the lower over-potential and the improved distribution uniformity of active species. The average concentration of semicircular design is 15.5 % higher than that of triangular channel at 3/4L cut plane. The uniformity factor of semicircular flow channel is 15.4 % higher than that of triangular channel. It is concluded that semicircular is the best design of channel section shapes, which can contribute to the application of the VRFBs.