TixOy loaded carbon felt as high performance negative for vanadium redox flow battery

To improve the power density and energy density of vanadium flow batteries (VFBs), a novel TixOy-loaded carbon felt (TixOy-CF) electrode is designed, fabricated, and applied. TixOy (consisted of TiO2 and Ti4O7) has the advantages of easy preparation, high electrical conductivity, good stability, etc. It is evenly distributed on carbon felt and shows high catalytic efficiency on V2+/V3+ redox couple to facilitate the electrochemical kinetics of the vanadium redox reactions. As a result, the VFB assembled with TixOy-CF achieves a high energy efficiency of 82.0% at a current density of 200 mA cm−2, and maintains 77.9% energy efficiency at 260 mA cm−2. In addition, the VFB with TixOy-CF exhibits good stability and high capacity retention within 400 cycles at 100 mA cm−2. This work provides a new perspective for the development of highly active electrodes for VFBs.