Single-Particle Nanoimpact Electrochemistry Reveals Zn2+ Storage Dynamics in CuMn Prussian Blue Analogues

Abstract Electrochemical analysis of single particles offers insights into charge-storage mechanisms in aqueous zinc-ion batteries (AZIBs). Prussian blue analogues (PBAs) are promising cathodes due to their open-framework structures and excellent Zn2+ transport. However, Zn2+ storage at the single-particle level remains unclear. This study introduces a diagnostic approach using nanoimpact electrochemistry (NIE) at an ultramicroelectrode (UME) to capture transient current signals from PBA particle collisions. Analysis of these stochastic signals reveals particle-level electrochemical activity, enabling direct observation of Zn2+ insertion and extraction dynamics. Bulk tests confirm the capacity of the cathode as 208.2 mAh g–1 at 0.1 A g–1 with reversible charge storage over 2000 cycles, retaining 88% capacity with 100% Coulombic efficiency. In situ Raman spectroscopy reveals a correlation between redox-active site evolution and Zn2+ movement within the PBA. By linking single-particle events to battery performance, this work advances the understanding of Zn-ion storage and demonstrates the utility of NIE in battery research.