Recent Advancements in the Interfacial Stability of Garnet Solid Electrolytes and Design Strategies for Solid-State Lithium Batteries: A Review

Solid-state lithium batteries (SSLBs) utilize solid electrolytes (SEs) instead of their liquid counterpart, providing higher energy density and safety, and are considered as potential energy storage technology. Among the various kinds of SEs, the garnet (Li 7 La 3 Zr 2 O 12, LLZO) solid electrolyte has considerable Li-ion conductivity and robust air/chemical stability, rendering it an excellent candidate for the commercialization of SSLBs. In recent years, numerous efforts have been made to improve the ionic conductivity of garnet SEs. These efforts have successfully achieved a high conductivity of ∼10 –3 S cm –1 at room temperature. Nevertheless, an emerging issue pertains to the interfacial stability of garnet-based solid electrolytes. Therefore, our focus lies on the interfacial challenges associated with garnet-based SSLBs, including (i) the interface between the lithium metal anode and the garnet SE, (ii) the interface between the garnet SE and high-voltage cathodes, and (iii) the interface between polymeric additives and garnet SE. The solution strategies for these target-oriented interfacial issues are briefly discussed. In light of the discourse on enhanced interfacial performance, the principle of designing high-performance interfaces is proposed. A future perspective is also offered for the development of SSLBs.