Stable sodium metal batteries by in-situ construction of multifunctional Mg-based interfacial layer in commercial carbonate-based electrolyte

Abstract

Sodium metal batteries (SMBs) are attractive energy storage devices due to the low electrochemical potential of metallic sodium and large abundance of sodium element in the earth crust. However, sodium metal anode faces challenges of inevitable dendrite and unstable interface, which blocks the commercial application of SMBs. Herein, a multifunctional sodiophilic Mg-based interfacial layer is constructed on the surface of sodium metal anode by a simple and scalable in-situ reduction strategy. The Mg-based interfacial layer can effectively suppress the growth of sodium dendrite and improve the interfacial stability. First-principles calculations prove that a strong interaction is constructed between the Mg and Na atoms, which indicates that the Mg-based interfacial layer can anchor the Na atom and guide Na deposition. The calculation results also show the Mg-based interfacial layer can obviously decrease the diffusion barriers during the electrochemical process. Under the regulation of the multifunctional Mg-based interfacial layer, the electrochemical performance of symmetric and full cells is obviously improved in commercial carbonate-based electrolytes. This work provides an avenue to build protective layer on metal-based anodes for developing high-security and high-energy-density rechargeable batteries.