From Nanoalloy to Nano‐Laminated Interfaces for Highly Stable Alkali‐Metal Anodes

Abstract Metal anodes are considered the holy grail for next‐generation batteries because of their high gravimetric/volumetric specific capacity and low electrochemical potential. However, several unsolved challenges have impeded their practical applications, such as dendrite growth, interfacial side reactions, dead layer formation, and volume change. An electrochemically, chemically, and mechanically stable artificial solid electrolyte interphase is key to addressing the aforementioned issue with metal anodes. This study demonstrates a new concept of organic and inorganic hybrid interfaces for both Li‐ and Na‐metal anodes. Through tailoring the compositions of the hybrid interfaces, a nanoalloy structure to nano‐laminated structure is realized. As a result, the nanoalloy interface (1Al 2 O 3 –1alucone or 2Al 2 O 3 –2alucone) presents the most stable electrochemical performances for both Li‐and Na‐metal anodes. The optimized thicknesses required for the nanoalloy interfaces for Li‐ and Na‐metal anodes are different. A cohesive zone model is applied to interpret the underlying mechanism. Furthermore, the influence of the mechanical stabilities of the different interfaces on the electrochemical performances is investigated experimentally and theoretically. This approach provides a fundamental understanding and establishes the bridge between mechanical properties and electrochemical performance for alkali‐metal anodes.