October 11, 2025
Journal Article
Electronic Structure and Safety Insights into Prussian Blue Analog Cathode Behavior at Elevated Temperatures in Sodium-Ion Batteries
Abstract
Prussian blue analogs (PBAs) represent promising cathode materials for sodium-ion batteries (SIBs) due to their high theoretical capacity, open framework structure, and use of earth-abundant elements. However, the high-temperature structural evolution, water content effects, and thermal safety of PBAs, particularly in charged states, remain poorly understood, hindering their practical deployment. Here, we investigate Na2Fe[Fe(CN)6]·2H2O using thermogravimetric analysis (TGA), ex-situ and in-situ temperature-dependent X-ray absorption spectroscopy (XAS), and accelerated rate calorimetry (ARC). TGA and ex-situ XAS confirm water loss between 150–200 °C, resulting in Fe2+ oxidation, enhanced local symmetry, and uniform redox behavior that improves electrochemical performance. In-situ XAS reveals irreversible structural changes above 240 °C, including ligand loss, Fe site distortion, and increased disorder, while ARC on charged electrodes shows minimal self-heating rates (Published: October 11, 2025