Customizing the morphology and microstructure of single-crystalline Ni-rich layered cathode materials for all-solid-state batteries

A single-crystalline Ni-rich cathode material is synthesized for high-performance all-solid-state batteries (ASSBs). We customize the morphology and microstructure of the material by optimizing the synthesis process (particle size control and post-heat treatment) and demonstrate the advantages of single-crystalline cathode materials for practical use in ASSBs. The particle density and particle hardness of single-crystalline cathode materials with a particle size of 5 μm are considerably higher than those of the conventional polycrystalline cathode materials that are composed of spherical aggregates of submicron-scale primary particles. These structural features of the single-crystalline cathode materials improve the long-term cycling performance and rate capability of an ASSB configured with an argyrodite–Li6PS5Cl solid electrolyte. This is mainly attributed to the intimate interfacial solid–solid contacts and enhanced diffusion kinetics induced by the monolithic morphology of the single-crystalline cathode materials in the electrode. Moreover, undesirable microcrack formation and particle fracture in cathode materials are effectively suppressed during cycling. The feasibility of ASSBs configured with single-crystalline Ni-rich cathode materials is examined in detail.