Infiltration -driven performance enhancement of poly-crystalline cathodes in all-solid-state batteries

Abstract All-solid-state batteries (ASSBs) with adequately selected cathode materials exhibit a higher energy density and better safety than conventional lithium-ion batteries (LIBs ). Ni-rich layered cathodes are benchmark materials for traditional LIBs owing to their high energy density. Recent studies have highlighted the advantages of using crack-free, single-crystalline cathode materials in ASSBs . In this study, a scalable infiltration sheet-type process was used to fabricate composite electrodes with different cathode-material morphologies for ASSBs . Typically, crack-free single-crystalline materials exhibit a better retention performance and lower rate capability than polycrystalline cathode materials. In this study, Li6PS5Cl-infiltrated polycrystalline electrodes showed an excellent retention performance and rate capability. Galvanostatic intermittent titration technique analysis and transmission electron microscopy confirmed severe polarization and the presence of a rock-salt-structure layer in cathode particles, indicating side reactions within the layered structure of the material. In contrast, composite electrodes comprising polycrystalline cathode materials infiltrated with the solid electrolyte Li6PS5Cl showed an excellent electrochemical performance owing to intimate electrode–electrolyte interfacial contact. This study confirms the critical influence of interface engineering and material morphology on the overall performance and stability of ASSBs, and could facilitate the development of high-performance ASSBs in the future .