Study on the Correlation between i _pa and i _pc of Electrode in Vanadium Flow Batteries by In‐Situ Weak Measurement Imaging

Abstract Traditional characterization techniques for vanadium flow batteries (VFBs) electrodes demonstrate significant limitations in resolving spatially heterogeneous reaction characteristics on electrode surfaces and efficiently characterizing large‐scale working electrodes. Consequently, mapping electrode activity distributions and establishing efficient screening strategies for high‐performance electrodes are critical for advancing VFBs research. Building on prior studies, this work employs weak measurement imaging (WMi) methodology to spatially characterize reaction activity distributions on VFBs positive electrode surfaces and quantitatively analyze electrode reaction parameters (i _pa and i _pc ). By statistically comparing extensive electrochemical data from working electrodes (randomly sampled from large graphite felt substrates and tested via electrochemical workstation, EW) with WMi‐derived data from individual electrodes, a pronounced linear correlation between oxidation and reduction peak current densities (i _pa and i _pc ) in VFBs working electrodes is identified. Systematic investigations of graphite felt (GF) and thermally activated graphite felt (TGF) electrodes under varied operational conditions confirmed this statistical relationship between i _pa and i _pc while validating the reliability of the WMi sensing system. This findings demonstrate that the WMi sensing system serves as a robust and versatile analytical tool for quantitatively characterizing electrode performance parameters. This approach facilitates efficient screening of high‐performance VFBs working electrodes, thereby accelerating the development of flow battery technologies.