The Aging Characteristics of DBD-treated Carbon Felt Electrodes and the Corresponding Strategy

The carbon felt is the most common used material for Vanadium Redox Flow Batteries (VRFBs) electrode. To enhance the electrochemical activity of carbon felt electrodes, plasma treatment is frequently employed. However, the temporal stability of modified carbon felt remains a critical issue that requires solution. In this study, the aging characteristics of the interface property of carbon felt modified by Dielectric Barrier Discharge (DBD) was investigated, and the corresponding strategy was proposed. Results showed that the DBD-treated carbon felt exhibited significantly enhanced hydrophilicity due to the formation of hydrophilic groups on its surface. Assembled VRFBs achieved an energy efficiency as high as 85%. After one month of storage in air, the energy efficiency of the VRFBs dropped to 70% with increased water contact angle and decreased hydrophilic functional group. To extend the useful-life of the DBD-treated carbon felt, we stored the samples in vacuum chamber and vacuum-sealed bags. The hydrophilicity of the carbon felt stored under vacuum conditions was superior to that of the air-exposed samples. And the energy efficiencies of VRFBs assembled from these stored carbon felts were maintained at 76% and 80% after one month, respectively, which was effectively enhanced compared to that stored in air. These findings provide methods for prolonging the effectiveness of DBD-modified carbon felt, thereby enhancing the practical applicability and long-term performance of VRFBs.