All-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 degrees C exhibited an LATP/LCO interface structure, providing superior contact and possibly improving the electrochemical properties of the ASS-LIB composite accordingly.