Predicting anode coatings for solid-state lithium metal batteries via first-principles thermodynamic calculations and hierarchical ion-transport algorithms

Abstract

Solid-state lithium metal batteries (SSLMBs) are promising for next-generation energy storage devices due to their superior energy density and excellent safety. Among solid-state electrolytes, garnet-type Li7La3Zr2O12 (LLZO) exhibits a wide electrochemical window and high lithium-ion conductivity, but poor electrode contact and Li dendrite growth restrict its practical application. To address these challenges, this study explores the application of thin film coatings composed of Li8MP4 (M = Si, Ge) at the lithium metal anode/LLZO interface. Through comprehensive first-principles thermodynamic calculations and hierarchical ion-transport algorithms, the phase stability, electrochemical stability, chemical stability, ionic transport, Li wettability, and mechanical properties of the candidate materials were systematically predicted and analyzed. Results indicate that the candidate coatings are thermodynamically stable at 0 K, with superior reduction stability against the lithium metal anode and good chemical compatibility with LLZO. Their Li-ion migration barriers are as low as 0.32 eV, enabling room-temperature ionic conductivity of approximately 10−5 S/cm. Moreover, the predicted works of adhesion for Li/Li8MP4 (M = Si, Ge) are 0.99 and 0.76 J/m2, respectively, corresponding to the contact angles of 0° and 49.3°, indicating that metallic Li shows good wettability on Li8MP4 (M = Si, Ge) materials. This work provides a comprehensive understanding of the thermodynamic and dynamic behaviors of Li8MP4 (M = Si, Ge) coatings and will guide the experimental design for desired SSLMB anode coatings.