High-performance bipolar plate of thin IrOx-coated TiO2 nanotubes in vanadium redox flow batteries

Thin DSA (dimensionally stable anode) bipolar plates designed to replace thick graphite were employed for the first time to obtain improved dimensions, and electrochemical catalytic properties in all-vanadium redox flow batteries (VRFBs). We found that a 0.127 mm-thick DSA consisting of nanotubular TiO2 on Ti substrate coated with a layer of IrOx worked extremely well as a bipolar plate. Using this material, overpotential and charge transfer resistance for charging and discharging were reduced due to the catalytic properties of IrOx, which improved the transfer of electrons or the electrical current. Furthermore, the stability of the IrOx layer on the TiO2 nanotubular structure grown from the Ti substrate was confirmed after 100 cycles. The efficiency of the VRFB based on the DSA bipolar plate increased by 3-4% compared to that of the graphite bipolar plate, suggesting that this thin DSA bipolar plate offers not only dimensional advantages, but also electrochemical advantages for VRFB applications.