Inorganic Solid Electrolytes for Achieving Intimate and (Electro)chemically Stable Interfaces for All-Solid-State Batteries

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. Specifically, establishing intimate contacts between electrode active materials and SEs poses substantial challenges. Moreover, these interfacial contacts may degrade owing to the repeated volume changes in electrode active materials. 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.

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.

 
References:

(1)    ACS Energy Lett. 2022, 7, 1776.

(2)    Adv. Energy Mater. 2023, 13, 2301142.

(3)    Adv. Energy Mater. 2018, 8, 1800035.