Enhanced Electrochemical Performance of Vanadium Redox Flow Batteries Using Li4Ti5O12/TiO2 Nanocomposite‐Modified Graphite Felt Electrodes

• Published in: ChemElectroChem Vol. 12; no. 2
• Main Authors: Huang, Zih‐Jhong, Manaye Kabtamu, Daniel, Mebreku Demeku, Aknachew, Chen, Guan‐Cheng, Hsu, Ning‐Yih, Ku, Hung‐Hsien, Wang, Yao‐Ming, Chiang, Tai‐Chin, Wang, Chen‐Hao
• Format: Journal Article
• Language: English
• Published: Weinheim John Wiley & Sons, Inc 14.01.2025; Wiley-VCH
• Subjects: Current density; Electrocatalysts; Electrochemical activity; Electrochemical analysis; Electrodes; Energy efficiency; Energy storage system; Graphite; Graphite felt; Heat treatment; Heat treatments; LTO/TiO2; Nanocomposites; Nanotechnology; Nanowires; Thermal cycling; Titanium dioxide; Vanadium; Vanadium redox flow battery
• ISSN: 2196-0216; 2196-0216
• DOI: 10.1002/celc.202400477

In this study, Li4Ti5O12 (LTO) and TiO2 nanocomposites uniformly were synthesized on the heat‐treated graphite felt through (HGF) hydrothermal and heat treatment methods, denoted by LTO/TiO2@HGF, which LTO/TiO2@HGF acts as effective electrocatalysts to enhance the electrochemical activity in vanadium redox flow battery (VRFB) systems. The cyclic voltammetry (CV) curves of the LTO/TiO2@HGF show higher peak current densities and smaller peak separation than TiO2@HGF, HGF, and pristine graphite felt (PGF) for catalyzing V2+/V3+ and VO₂+/VO2+, indicating superior electrochemical activity of LTO/TiO2@HGF. The VRFB using LTO/TiO2@HGF as the positive and negative electrodes demonstrates an energy efficiency of 82.89 % at 80 mA cm−2. When the VRFB using LTO/TiO2@HGF is applied by a high current density of 200 mA cm−2, it still shows an energy efficiency of 62.22 %. However, the VRFB using PGF cannot perform any performance, and the VRFB using HGF only performs 51.94 %. This improvement can be attributed to the uniform distribution of LTO/TiO2 nanowires on the surface of the graphite felt and the presence of oxygen vacancies on LTO/TiO2, which increased the number of active sites for vanadium ion absorption. The study synthesizes LTO/TiO2 nanocomposites on heat‐treated graphite felt (LTO/TiO2@HGF) for the VRFB. This composite demonstrates superior electrochemical activity compared to TiO2@HGF, HGF, and pristine graphite felt. The VRFB using LTO/TiO2@HGF achieves 82.89 % energy efficiency at 80 mA cm−2 and 62.22 % at 200 mA cm−2. Improved performance is attributed to uniform nanowire distribution and oxygen vacancies, enhancing vanadium ion absorption.