Organized macro-scale membrane size reduction in vanadium redox flow batteries: Part 1. General concept

Abstract

The high costs of the currently used membranes in vanadium redox flow batteries (VRFBs) contribute to the price of the vanadium redox flow battery systems and therefore limit the market share of the VRFBs. Here we report a detailed simulation and experimental studies on the effect of membrane reduction of single-cell VRFB. Different simulated designs demonstrate that a proposed centred and double-strip membrane coverage showed a promising performance. Experimental charge-discharge profile of different membrane size reduction, which showed good agreement with simulated data, suggests that the membrane size can comfortably be reduced by up to 20% without severe efficiency or discharge capacity loss. Long-term cycling of 80% centred membrane coverage showed improved capacity retention during the latter cycles with almost 1% difference in capacity and only 2% in energy efficiency when compared to the fully covered-membrane cell. The results hold great promise for the development of cheap RFB stacks and facilitate the way to develop new cell designs with non-overlapping electrodes geometry. Therefore, giving more flexibility to improve the overall performance of the system.