Carbon felt coated with titanium dioxide/carbon black composite as negative electrode for vanadium redox flow battery

This investigation focuses on the effect of titanium dioxide (TiO ₂) coatings of a carbon black (XC-72) negative electrode on the performance of a vanadium redox flow battery (VRFB). TiO₂, a hydrophilic material, was added to the carbon electrode to improve the wettability and reduce the electrical resistance of the electrode surface. The electrochemical performances of homemade TiO₂, commercial TiO ₂, and carbon felt are investigated by using cyclic voltammetry and single-cell charge-discharge measurements. An electrode with 20 wt% of fabricated TiO₂ loading at a scan rate of 0.006 V s_-1 shows a specific capacitance (Cs,t) of 186.2 Fg_-1, which is 55.5% and 12.2% higher than that of pure carbon electrode (119.7 Fg_-1) and commercial TiO₂ (166.0 Fg_-1), respectively. At current density of 200 mA cm-2, the energy storage efficiency (εE = 65.4%) of the single cell with 20 wt% homemade TiO₂/C-containing carbon felt negative electrode is 16.0% and 6.1% higher than that of the negative electrode with raw carbon felt (εE = 56.4%) and of the negative electrode containing commercial TiO₂/C (εE = 61.6%), respectively. These results demonstrate the potential application of TiO₂/C electrodes for high-efficiency VRFBs at high current densities.