Stable Sodium Metal Batteries via Manipulation of Electrolyte Solvation Structure

Abstract Sodium metal batteries have attracted rapidly rising attention due to their low cost and high energy densities. However, the instability and low efficiency of metallic sodium anodes pose significant concerns for their practical applications. Here a highly stable sodium metal anode enabled by an ether‐based electrolyte is reported, which exhibits a long‐term stable cycling up to 400 cycles and achieves an unprecedentedly average Coulombic efficiency of over ≈99.93%. It is revealed that the organic/inorganic hybrid structure containing B–O species and NaF in the ultrathin solid‐electrolyte interphase layer plays the key role for the outstanding electrochemical performances. Furthermore, a Na||Na 3 V 2 (PO 4 ) 3 full cell successfully achieves a stable cycling performance that paves the way for the development of sodium metal batteries.