Improve the Mass Transfer to Graphite Electrode Through Cell Design in Vanadium Redox Flow Batteries

Improve the mass transfer to graphite electrode through cell design in vanadium redox flow batteries

Feng Chen, Yuyan Shao, Qingtao Luo, Wei Wang, Liyu Li, Zimin Nie, Gary Yang

Pacific Northwest National Lab, Richland, WA99354

 

 

Abstract

  Electrolyte mass transfer is a key factor that affects the performance of vanadium redox flow battery (VRFB). Flow batteries with graphite felts inserted with graphite compounded plates were designed to investigate the influence of mass transfer between electrolyte and graphite fiber on the cell performance. Different amounts of graphite plates were applied in the cell design to explore the extent of influence of plate-like barriers on the mass transfer and diffusion rate of electro-active ions. Vanadium redox couples were used as the electro-active species. The flow batteries with new design were also tested under different flow rates to examine the combinational effect of flow rate and graphite plate barriers. Another set of PVC plate barriers were also employed in the new design to study the effect of barrier material on the cell performance.  It was shown that the coulombic, energy, and voltage efficiencies were greatly improved by applying the new electrode design in the flow battery system. The testing of cells with PVC insulated plates is still on-going. However, the testing of cell with new design under different flow rates needs to be repeated and verified.