Boyu Wang, Shichen Sun, Buke Wu, Kevin Huang
High Resolution Image Download MS PowerPoint Slide Aqueous zinc-ion batteries (AZIBs) are regarded as promising candidates for large-scale energy storage owing to their intrinsic safety, low cost, and environmental compatibility. However, their practical application is hampered by sluggish cathodic kinetics and poor cycling stability. Here, we systematically investigate the electrochemical kinetics of hydrated vanadium pentoxide (V 2 O 5 · n H 2 O, VOH) cathodes across the full state-of-charge (SOC) range in 1 M Zn(OTf) 2 electrolyte, employing a combined approach of galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EIS). Our quantitative evaluation reveals that the high-potential V 5+ + e – ⇌ V 4+ redox reaction exhibits more facile charge-transfer and diffusion kinetics than the low-potential V 4+ + e – ⇌ V 3+ redox reaction, which is strongly diffusion-limited and associated with higher polarization. Ex situ X-ray diffraction (XRD) and scanning electron microscopy (SEM) characterizations support that proton coinsertion induces reversible formation of alkaline layered double hydroxide (LDH) phases, which elevate interfacial resistance and hinder Zn 2+ transport at deeper states of charge. The findings of this work provide fundamental kinetic parameters and mechanistic insights for VOH cathodes, bridging electrochemical measurements with structural evidence and offering insights for future modeling and cathode design in AZIB systems.