Study of Spectral Analysis and Redox Potential Titration for Monitoring the State-of-Charge of Vanadium Redox Flow Battery

Wednesday, 4 October 2017
Prince George's Exhibit Hall D/E (Gaylord National Resort and Convention Center)
C. L. Hsieh (Institute of Nuclear Energy Research), Y. H. Hung (GlobalWafers Co., Ltd.), K. L. Hsueh (Industrial Technology Research Institute, National United University), and J. S. Hung (National United University)
Vanadium redox flow battery (VRFB) is currently the most mature technology of MW-level electricity storage. At present, the open circuit voltage of the electrolyte (OCV) is used to estimate the battery SOC (state-of-charge). Theoretically, the battery SOC cannot be estimated by measuring battery OCV along. Two analytical methods, UV-VIS absorption spectroscopy and redox electrode potential titration, were evaluated for assessing the electrolyte SOC. The UV-VIS spectra of solutions containing pure V2+, V3+, VO2+ ions can be identified. However, solutions containing a mixture of these ions cannot be easy identified. Redox potential titration analysis can identified individual ions from electrolyte sampled from positive electrode and negative electrode at SOC at 10%, 50%, 90%. Both OCV and UV-VIS are in-situ SOC monitoring method. The electrolyte composition is needed to be checked by redox potential titration at regular basis.