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). TiO 2 , 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 TiO 2 , 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 TiO 2 loading at a scan rate of 0.006 V s −1 shows a specific capacitance ( C s,t ) of 186.2 F g −1 , which is 55.5% and 12.2% higher than that of pure carbon electrode (119.7 F g −1 ) and commercial TiO 2 (166.0 F g −1 ), respectively. At current density of 200 mA cm −2 , the energy storage efficiency ( η E = 65.4%) of the single cell with 20 wt% homemade TiO 2 /C-containing carbon felt negative electrode is 16.0% and 6.1% higher than that of the negative electrode with raw carbon felt ( η E = 56.4%) and of the negative electrode containing commercial TiO 2 /C ( η E = 61.6%), respectively. These results demonstrate the potential application of TiO 2 /C electrodes for high-efficiency VRFBs at high current densities.