A novel carbon paper based flow field design strategy toward high power density vanadium flow battery operation.

The all-vanadium flow battery (VFB) is a promising candidate for long-duration energy storage. Flow field design is deemed as a critical approach to realize high power density operation for VFBs. However, conventional graphite bipolar plates still face mechanical limitations for practical stack uses, so there is an urgent need to explore alternative design strategies. Herein, a carbon paper based serpentine flow field (SFF) design is proposed for high power density VFB operation, which simultaneously reduces pressure drop and concentration polarization. Finite element analyses firstly compare different SFF designs and reveal effectively reduced pressure drop and promoted flow velocity across the electrode for 100 % SFF design. Subsequently, the 100 % SFF design presents significantly reduced concentration polarization at 200 mA cm−2 and 85 % SOC, which outperforms non-flow field and other SFF designs. Moreover, the full cell experiments demonstrate an enhanced voltage efficiency of 83.6 % at 200 mA cm−2 along with higher discharge capacity. By further coupling 100 % SFF with Bi catalyst, the VFB cell finally proves to deliver a 79 % voltage efficiency at 300 mA cm−2 and stably operate over 1000 cycles, which highlights the great potential of proposed design strategy to realize high power density VFB operations. • A carbon paper based flow field design strategy is proposed for VFBs. • Simulation results present reduced pressure drop and concentration polarization. • The flow cell with 100 % SFF delivers a voltage efficiency of 83.6 % at 200 mA cm−2. • Long-term cycling stability over 1000 cycles is realized by proposed design. [ABSTRACT FROM AUTHOR]