SEMINAR

The increasing safety concerns and the escalating demands for higher energy density in lithium-ion batteries necessitate a transition from flammable organic liquid electrolytes with inorganic solid electrolytes (SEs). Several characteristics are crucial for SEs to be integrated into practical all-solid-state batteries (ASSBs); prominent among these are high ionic conductivity of at least 10^-3 S cm^-1 at room temperature and the mechanical sinterability, along with cost-effectiveness of the constituting elements. Both sulfide (or thiophosphate, e.g., Li₆PS₅Cl) and halide SEs (e.g., Li₃YCl₆) meet these requirements. In ASSBs, designing composite cathodes or interfaces between the electrode/SE layers is pivotal, given the solid nature of SEs and the requisite of (electro)chemical stability. In this context, understanding interfacial evolution and developing novel interfacial engineering are imperative. Given their intrinsically high electrochemical oxidation stability above 4 V (vs. Li/Li⁺), there has been extensive exploration of new halide SEs recently. However, most compositions developed to date depend on scarce and expensive central metal elements like Y, Sc, and Ta, with Zr being the notable exception. Moreover, an overlooked compatibility issue betwwen different SEs should be addressed.

In this presentation, we will outline our progresses in the development of new sulfide and halide superionic conductors, focusing on achieving high-performance of ASSBs for practical applications.