Lithium Argyrodite Sulfide Electrolytes with High Ionic Conductivity and Air Stability for All-Solid-State Li-Ion Batteries
Yong‐Heum Lee, Jiwon Jeong, Ho Jun Lee, Mingony Kim, Daseul Han, Hyoungchul Kim, Jong Min Yuk, Kyung‐Wan Nam, Kyung Yoon Chung, Hun‐Gi Jung, Seungho Yu
Abstract
Solid electrolytes (SEs) are promising candidates for enhancing the energy density and safety of conventional lithium-ion batteries. Recently, lithium thioantimonate iodide argyrodites have been regarded as promising SEs because of their high ionic conductivities and air-stability. In this study, we utilized high-energy ball milling to synthesize Ge-substituted thioantimonate argyrodites and achieved an ionic conductivity of 16.1 mS cm–1 for Li6.5Sb0.5Ge0.5S5I, which is the highest value among the reported cold-pressed SE pellets. First-principles calculations reveal that concerted Li-ion migrations through the inter-cage paths substantially improve the ionic conductivity. Li6.5Sb0.5Ge0.5S5I shows good compatibility with LiNi0.5Co0.2Mn0.3O2-based all-solid-state batteries (ASSBs) after applying Li3YCl6 as a catholyte, which exhibits a high discharge capacity of 164 mAh g–1 and good cycle stability. Ge-substituted thioantimonate argyrodites exhibit excellent air-stability, which facilitates reducing the synthesis and fabrication costs of ASSBs with hygroscopic P-based sulfide SEs. The superionic conductors with high air-stability reported in this study demonstrate substantial promise for the development of ASSBs.