Designing a Stable Solid Electrolyte Interphase on Lithium Metal Anodes by Tailoring a Mg Atom Center and the Inner Helmholtz Plane for Lithium–Sulfur Batteries

Arising from the extraordinary theoretical energy density, rechargeable lithium-sulfur (Li–S) batteries have been reputed as one of the most appealing options for next-generation high-performance energy storage and conversion devices. Unfortunately, their industrial implementation has been strongly governed by the formation of Li dendrites caused by the unstable solid electrolyte interphase (SEI) film. Herein, we report a novel electrolyte by introducing the Mg(NO3)2additive to suppress the growth of Li dendrites, further improving the cycling lifetime of Li–S batteries. On the one hand, Mg2+can rapidly react with Li atoms to generate Mg atoms, replacing the Li atoms on the top surface of Li metal and forming the Mg center simultaneously. On the other hand, NO3–can be adsorbed in the inner Helmholtz plane and reduced as an inorganic-rich SEI film for stabilizing the Li metal anode when the electrolyte comes in contact with Li metal, effectively mitigating the formation of Li dendrites. Combining the experimental results and theoretical calculations, we confirm that the Mg atom center and the inorganic-rich SEI film are both beneficial for enhancing the electrochemical performance of Li–S batteries. This work provides a new insight into the electrolyte additive and a possible alternative for the design of high-performance Li–S batteries beyond the LiNO3additive.