Effective interfacial contacts and conductive pathways within composite electrodes are critical for enhancing the performance of all‐solid‐state batteries (ASSBs). Herein, we fabricated LiCoO 2 –Li 10 GeP 2 S 12 (LCO–LGPS) composites with uniform and nonuniform microstructures by controlling composite particle sizes and mixing conditions. The microstructured LCO–LGPS composites were characterized by scanning electron microscopy with energy‐dispersive X‐ray spectroscopy (SEM‐EDX), scanning spreading resistance microscopy (SSRM), and pico‐current conductive atomic force microscopy (C‐AFM). Results reveal that uniform microstructures produce large contact areas between LCO and LGPS with uniform 3‐dimensional (3D) e – /Li + ‐conductive pathways. However, in uniform microstructures, e – (LCO)‐ and Li + (LGPS)‐conductive pathways are interrupted by LGPS and LCO, respectively. In contrast, nonuniform microstructures provide small contact areas between LCO and LGPS, and both well‐ and poorly connected 3D conductive pathways are present. Increasing the microstructural uniformity decreases the overvoltage at low C‐rates but increases the overvoltage with increasing C‐rates because of the interrupted conductive pathways, even though they are uniformly distributed. These findings suggest that “well‐mixing” does not absolutely guarantee the enhanced performance of composite electrodes. It is important to construct e – /Li + ‐conductive pathways well‐connected and uniformly distributed like a 3D network. Our findings provide new insights for controlling the microstructures of composite electrodes.
Kang et al. (Fri,) studied this question.