Ti_xO_y 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 Ti_xO_y-loaded carbon felt (Ti_xO_y-CF) electrode is designed, fabricated, and applied. Ti_xO_y (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 Ti_xO_y-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 Ti_xO_y-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.