Electrolyte-Dependent Structure–Transport Relationships in Electrodeposited Prussian Blue Analogue Thin Films

Understanding how electrolyte composition influences the structural factors governing charge storage in Prussian Blue analogues (PBAs) requires clarifying the coupled effects of ion desolvation, structural disorder, and transport pathway connectivity. Here, we demonstrate that electrolyte identity induces structural disorder, which correlates with transport dispersion measured under identical electrochemical conditions. To establish this relationship, Fe-, Co-, and Ni-based hexacyanoferrate thin films were electrodeposited from chloride electrolytes (KCl, NaCl, NH4Cl, and LiCl), enabling a comparative investigation of structure-transport correlations across multiple length scales. Although all systems crystallize in the cubic PBA structure, pronounced electrolyte-dependent variations in lattice parameters, defect concentration, and local coordination environments are observed. Na+ induces lattice expansion but simultaneously promotes vacancy formation, microstrain, and structural heterogeneity, whereas K+ and NH4+ produce more structurally coherent frameworks with reduced disorder.