Micro-pillars enhanced all vanadium redox flow batteries and the effect of assembly torque on the electrochemical performance

A uniformly distributed electrolyte system based on enhanced micro-pillars flow field design is proposed for a vanadium redox flow battery (VRFB). The uniformity experiments show that the flow uniformity can be effectively increased and normalized velocity variation for any channel is measured to be less than 18 %, demonstrating the effectiveness of micro-pillars for enhanced flow field. Experimental validation is carried out experimentally and the effect of different assembly torque is also investigated for VRB cell electrochemical performance via polarization and cyclic voltammograms (CV) test. The results show that an optimal assembly torque (11 N-m) can yield a significant improvement of 68.5 % current density when compared with the case of 10 N-m. Furthermore, the CV results clearly indicate that the optimal assembly torque with enhanced micro-pillars design can result in the 37.3 % improvement of electrochemical surface area. Moreover, the contact pressure contours from the pressure-sensitive films are measured to check the influence on the configuration of VRFB unit cell.