STEM‐EELS analysis of the interface structures of composite ASS‐LIB electrodes fabricated via aerosol deposition

Abstract

AbstractAll‐solid‐state (ASS) lithium‐ion batteries (LIBs) are conventionally fabricated by sintering the component materials at high temperatures. However, interdiffusion between the two phases can give rise to problematic interfacial chemical compounds; therefore, an alternative fabrication method such as aerosol deposition (AD), which works near room temperature, is highly desirable in the ASS‐LIB research field. Herein, we examined the nanometric interface structures of composite ASS‐LIB electrodes fabricated using an AD method, with a particular focus on the structures of Li+‐conductive glass‐ceramic solid electrolyte Li1.3Al0.3Ti1.7(PO4)3 (LATP), which we analyzed using a non‐negative matrix factorization technique. We applied this technique to datasets obtained by combined scanning transmission electron microscopy and electron energy loss spectroscopy. The interface structure of a nonannealed composite could not be explained by the main crystal phase of pristine LATP particles or their surface structure, which should reflect a deposition process specific to the AD method. A composite annealed at 400°C exhibited an LATP/LCO interface structure, providing superior contact and possibly improving the electrochemical properties of the ASS‐LIB composite accordingly.