Manipulating the Size of Solid Electrolyte Particles via Spray-Recrystallization: Toward Reliable and High Energy Density All-Solid-State Batteries

Abstract

All-solid-state batteries (ASSBs) are gaining attention due to their high safety and energy density compared to those of conventional lithium-ion batteries (LIBs). However, insufficient contact between the cathode active material (CAM) and solid electrolyte (SE), or using a high proportion of SE in the cathode, hinders energy density improvements. Maintaining a low electrolyte proportion while ensuring sufficient Li-ion pathways is challenging. This study elucidates the correlation between SE particle size distribution and electrode microstructure, as well as Li-ion and charge transfer kinetics. A spray-recrystallization method is introduced to control the size of SEs. Exquisite SE size control allows the intimate interface between CAM and SE as well as homogeneous SE distribution, enhancing Li-ion transport kinetics and corresponding to reducing charge transfer resistance (Rct) and Li-ion migration resistance (Rion). A full cell with an NCM/SR-LPSCl cathode shows a reversible capacity of 171.6 mAh g-1, 74.1% cycle retention after 100 cycles, and 113.7 mAh g-1 at room temperature. It is confirmed that the cathode containing 90 wt.% NCM and a high areal capacity of 15 mAh cm-2 is maintained stably, and the impact of the particle distribution of sulfide-based SEs on Rion and Rct.