Enhanced energy density and electrochemical performance of all-solid-state lithium batteries through microstructural distribution of solid electrolyte

Maximizing the proportion of active material in the composite cathode is a technical challenge for the All-Solid-State Lithium ion battery. Among viable solutions, employing a powder with minimized and uniform size distribution might be the most effective and practical solution. To address this issue, we carefully control the size of the high ionic conducting Li2S-P2S5 solid electrolyte to a smaller and narrower size distribution than standard solid electrolyte. We show the milled electrolytes have significantly higher capacity than standard one in the composite cathode. Electrochemical impedance spectroscopy suggests that both the active material-solid electrolyte interfacial resistance and the solid electrolyte pathway resistance through the composite cathode are important. Moreover, at higher active material ratios, the resistance through ion conducting pathways becomes the most limiting factor for discharge rates. A preliminary model is suggested to guide future development of the microstructure in all-solid-state batteries.