Improved calculation framework for Prussian Blue analogues as a battery material

Abstract

Prussian Blue analogues are promising, low-cost cathodes for sodium-ion batteries, yet their complex mixed-valent and polymorphic nature challenges predictive modeling. This study provides a transferable density functional theory calculation framework for Prussian Blue analogues in sodium-ion battery applications by systematically benchmarking six representative exchange–correlation functionals across three sodiation states and two structural modifications (cubic and rhombohedral). We evaluate structural and electronic properties, open-circuit voltages, and the sodium ion transport via two prominent migration mechanisms. Additionally, we highlight the differing computational requirements for modeling Prussian Blue analogues either as half-filled, mixed-valent compounds with a strong focus on the electronic structure or as high-grade functional battery materials, where an accurate prediction of the phase stability and the ion transport is essential. Our results establish practical recommendations for reliable density functional theory studies of Prussian Blue analogues, warn of pitfalls to be avoided and lay the groundwork for high-throughput screening of sustainable sodium-ion battery materials.