Mixed ionic-electronic conductors-based artificial SEI layers for stabilizing interfaces and suppressing dendrites in garnet solid electrolytes

초록

All-solid-state batteries (ASSBs) have attracted significant attention as next-generation energy storage systems for their superior safety and energy density, achieved by replacing flammable liquid electrolytes with solid-state electrolytes. Garnet-based Li7La3Zr2O12 (LLZO) has emerged as a promising solid electrolyte due to its high ionic conductivity, wide electrochemical stability window, and chemical compatibility with Li metal. However, interfacial issues at the LLZO/Li interface, such as poor contact, low wettability, and Li dendrite formation, remain critical obstacles to the commercialization of ASSBs. In this study, the mechanisms and effects of Z-LLZ (ZnO-coated LLZO) and AZ-LLZ (AZO-coated LLZO) as artificial solid electrolyte interphase (ASEI) layers at the LLZO/Li interface were investigated. Z-LLZ exhibited effective interfacial stabilization and dendrite suppression through reversible conversion and in-situ reaction mechanisms, forming Li2O and Li-Zn alloys. Meanwhile, AZLLZ improved chemical stability through Al doping; however, irreversible side reactions led to the formation of resistive by-products, such as LiAlO2, which limited its performance. Experimental results showed that Z-LLZ achieved superior interfacial stability and electrochemical performance, while AZ-LLZ improved contact properties but exhibited reduced ionic conductivity. This study highlights the importance of optimizing ASEI designs tailored to battery requirements and operating conditions to resolve interfacial challenges in LLZO-based ASSBs. The findings provide a novel approach and foundational insights into the practical development of nextgeneration energy storage systems.

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