Experimental verification of electrode activation for improved performance in vanadium redox flow batteries

Vanadium redox flow batteries (VRFBs) have held significant promise in large-scale energy storage applications due to their advantages, including long cycle life, high safety, and the ability to independently design power and capacity. However, the relatively low power density has remained a critical bottleneck for further development. As a key material in VRFB power units, enhancing the performance of graphite felt electrodes has represented an effective strategy for achieving high-power battery technology. To improve the activity of graphite felt electrodes, this study has employed an experimental verification approach to investigate battery performance parameters under various activation temperatures and durations, thereby identifying the optimal activation conditions. In contrast to prior studies that exclusively targeted 400°C without systematically optimizing activation duration, this study has systematically evaluated five activation temperatures and four activation durations to clarify the synergistic influence of these parameters on VRFB performance. Specifically, experiments have been conducted at room temperature using activation temperatures of 300, 350, 400, 450, and 500°C, as well as activation durations of 24, 11, 7, and 3 ​h. The results have indicated that an activation temperature of 400°C yielded notable improvements in charge/discharge performance, internal resistance, efficiency, and capacity retention. Notably, energy efficiency has increased by 5.06%, 5.94%, 3.67%, and 4.72% under these conditions. This study has identified the optimal activation conditions of “400°C for 7 ​h” and has provided the corresponding performance data, which can help reduce research costs associated with electrode activation in future investigations. This study has provided valuable insights into electrode activation and has offered guidance for enhancing VRFB performance. • Determine the optimal temperature and duration for thermal activation through systematic experimentation. • Evaluate the variations in battery performance at the optimal activation temperature. • Investigated the coupling mechanism between electrode thermal activation and battery performance.