Crystalline/amorphous LiCoO2–Li2SO4 nanoheterostructured materials for high-voltage all-solid-state lithium batteries

Amorphous active materials have been developed for high-performance lithium and sodium secondary batteries to achieve a higher capacity, higher rate performance, and longer cycle life than those of crystalline active materials. In this study, a new function of amorphous active materials was explored through the heat treatment of pseudobinary amorphous materials (for example, LiCoO2–Li2SO4). Additionally, active materials with crystalline/amorphous nanoheterostructures, in which the nano-LiCoO2 domains were dispersed in a Li2SO4-rich matrix, were demonstrated. In all-solid-state batteries with sulfide solid electrolytes (SEs), the crystalline/amorphous active materials reduced the interface resistance of the active material and SE when compared with that of Li. High electrochemical performance was achieved using the Li2SO4-rich matrix, which served as an interfacial stabilizer. In summary, this paper reports a new strategy based on annealing amorphous materials for developing active materials with nanoheterostructures for high-performance energy storage devices.