3D observation using TEM tomography of solid electrolyte–electrode interface in all-solid-state Li-ion batteries.

Electron tomography is an observation technique for nanometer-scale three-dimensional structures, using transmission electron microscopy (TEM). TEM tomography has been used to examine the 3D structures of various materials, such as biological samples and catalysts. In this study, we applied TEM tomography to battery materials. All-solid-state lithium-ion batteries have recently received much attention owing to their thermal safety. In all-solid-state cells, the electrode layer is composed of nonflammable solid electrolytes and electrode active materials. In order to improve the charge–discharge cycle performance, it is necessary that the electrolyte–electrode interface has no void spaces or defects. We used TEM tomography to investigate the solid interfaces of Sn–Li3PS4 (LPS) negative electrode composites of all-solid-state cells. We observed that Sn, Li-Sn alloy nanoparticles, and LPS glass electrolytes formed a solid interfacial contact with no void spaces during initial charge–discharge cycles. We suggest that as a new cycle deterioration analysis method, TEM tomography is useful in evaluating solid interfaces in all-solid-state cells. [ABSTRACT FROM AUTHOR]