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 (R ct ) and Li‐ion migration resistance (R ion ). 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 R ion and R ct .