Carbon-composite bipolar plate-integrated current collector for vanadium redox flow battery

Abstract

In vanadium redox flow battery (VRFB stacks), a common issue is the deflection experienced by the endplate with tie bars, resulting in inadequate electrical contact between the copper current collector (CC) and graphite bipolar plate (BP) of the terminal cell. This contact deficiency leads to a decrease in efficiency and there has been limited exploration of interfacial contact resistance between BPs and CCs. To address this issue, a composite bipolar plate that enables the BP to be integrated with the CC through co-curing was developed in this study. The electrical properties of the BP-integrated CC were investigated by considering the surface roughness of the copper and the curing pressure. Additionally, a finite element analysis (FEA) was conducted to study the effect of the curing pressure on carbon fiber indentation on the copper surface. Charge/discharge tests were conducted; the results demonstrate that the energy efficiency of the developed BP-integrated CC is up to 4.1 % greater compared to that of conventional configurations wherein the BP and CC are separate. The findings of this study can help improve the stack performance of VRFBs and present a solution for corrosion at the BP–CC interface, leading to considerable economic benefits in large-scale VRFB systems.