Reactional Analysis in Oxide-Type All-Solid-State Na-ion Batteries by Multi-Scale Analysis Using Operando Measurements

Abstract

All-solid-state batteries (ASSBs) with oxide-type solid electrolytes are attracting significant attention due to their superior chemical stability and safety. Additionally, the use of sodium (Na), as a carrier ion can lead to the development of cost-effective and sustainably supplied ASSBs. However, the reactions within ASSBs are highly complicated at each component material and their interfaces during charge-discharge cycles.

In this study, we developed a multi-scale analytical approach that integrates operando scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), operando Raman spectroscopy, and time-of-flight secondary ion mass spectrometry (TOF-SIMS) to elucidate hierarchical reactions from the atomic to the micrometer scales. The multi-scale analysis demonstrated that operando SEM-EDS and Raman spectroscopy provide complementary evaluations of Na concentration changes in the electrode layers at the micrometer scale and crystal structural changes in the electrode active material at the atomic scale. Furthermore, TOF-SIMS offers precise observations of elemental distributions at the nanometer scale.