Introducing Crown Ether as a Functional Additive for High-Performance Dendrite-free Li Metal Batteries

Lithium metal has long been considered as the most promising anode due to its lowest reduction potential and ultrahigh energy density (3860 mA h g–1). However, the practical application of the lithium metal anode has been hindered by the limited volume evolution and undesirable dendritic structure. To address these thorny issues, we introduce 18-crown-6 as an additive to enhance the Coulombic efficiency and cycling stability of the Li metal anode. An optimal amount (1 wt %) of 18-crown-6 can not only promote the decomposition of lithium salts in the electrolyte to form a solid electrolyte interface (SEI) layer but also improve the electrolyte conductivity. The SEI layer with high ionic conductivity and strong mechanical properties can promote lithium ion diffusion and inhibit the growth of lithium dendrite and thus promote cycling stability, Coulombic efficiency, and rate performance of the cell. This work highlights the importance of 18-crown-6 in the electrolyte and reveals a new avenue to suppress the Li dendrites for lithium-based energy storage devices.