LTO/TiO2 Nanowire-Decorated on Graphite Felt As Electrode for High-Performance Vanadium Redox Flow Battery

Abstract

Vanadium redox flow battery(VRFB) is one of the most promising large-scale energy storage systems. However, the graphite electrode materials employed for VRFB often have shortcomings such as poor electrochemical activity and insufficient conductivity, which will lead to poor performance of VRFB. To modify the graphite electrode, in this study, lithium titanate/titanium dioxide(LTO/TiO2) composite catalyst with the nanowire morphology was directly grown on the surface of the heat treatment graphite felt(HGF). The graphite felt electrode through the nanowire morphology, the reaction area between the electrode and the electrolyte and active sites are increased, thereby improving the performance of VRFB. In order to further prove the effect of lithium titanate/titanium dioxide composite catalyst modified graphite felt(LTO/TiO2@HGF), the modified graphite felt electrode was applied to the positive and negative electrodes of VRFB, and the charge and discharge tests at different current densities were carried out. In terms of efficiency, the LTO/TiO2-modified graphite felt electrode has obviously better results. When the current density is increased to 200 mA/cm2, its energy efficiency can reach 60.57%, which is 8.63% higher than that of HGF. In the stability test with a current density of 160 mA/cm2, the VRFB was charged and discharged for 60 cycles, and the overall performance did not change significantly, which means that the composite material of lithium titanate and titanium dioxide not only effectively improve the performance of the VRFB, but also show the stability that can be used for a long time.