All-Solid-State Thin-Film Lithium-Selenium Batteries

All-solid-state batteries (ASSBs) with high-energy-density and enhanced safety are ideal for next-generation energy storage in electric transportation and Internet of Things. Fundamentally, the augmentation of their energy density relays on advanced cathode materials. This imperative has driven growing interest in Se-based cathodes, which demonstrate a high volumetric energy density, as well as higher electrical conductivity and better environmental adaptability compared to the well-known S cathodes. However, to ensure sufficient mechanical strength and mitigate the continuous deterioration of the solid-solid interface caused by the substantial volume expansion of the Se, the all-solid-state Li-Se batteries reported thus far typically employ thick solid electrolytes (50-200 mu m), which severely limits their energy density. Here, the first successful fabrication of all-solid-state thin-film Li-Se batteries is reported, featuring an ultra-thin (approximate to 1.4 mu m) lithium phosphorus oxynitride solid electrolyte and a hybrid Se cathode supported by vertical graphene nanoarrays (VGs). The conductive VGs, serving as the Se host, effectively mitigate the volume change during cycling and ensure stable solid-solid contact. Consequently, the cells exhibit over 1000 stable cycles with a capacity retention rate of 89% are attained in the "all-thin film" configuration. This study provides a novel design strategy for the development of next-generation high-performance ASSBs.