Operando Synchrotron-Based X-ray Study of Prussian Blue and Its Analogue as Cathode Materials for Sodium-Ion Batteries

Abstract

In this study, we employed operando synchrotron-based X-ray techniques to monitor potential-dependent oxidation-state changes of metal components and lattice spacings of Prussian blue (PB) and its analogues as sodium-ion battery materials in real time. Operando X-ray absorption near edge structure measurements revealed that iron is the only redox active component in both PB and its analogue substituted with nickel (PBN). Operando X-ray diffraction measurements revealed that relative to PB, PBN shows better structural stability and rate capability, ascribed to smaller volumetric changes during cycling and state of charge as well as larger diffusion coefficients.