Dendrite-Free Li Metal Anode for Rechargeable Li-SO2 Batteries Employing Surface Modification with a NaAlCl4-2SO2 Electrolyte.

Dendritic growth of a Li metal anode during cycling is one of major issues to be addressed for practical application of Li metal rechargeable batteries. Herein, we demonstrate that surface modification of Li metal with a Na-containing SO2 electrolyte can be an effective way to prevent dendritic Li growth during cell operation. The surface-modified Li metal anode exhibited no dendritic deposits even under a high areal capacity (5 mA h cm-2) and a high current density (3 mA cm-2), whereas the unmodified anode showed typical filamentary Li deposition. The surface-modified Li metal anode also demonstrated significantly enhanced electrochemical performance, which could be attributed to the newly formed Na-containing inorganic surface layer that exhibits uniform and dense properties. Consequently, surface modification with a Na-containing SO2 inorganic electrolyte is suggested as one of the most effective ways to realize a highly stable Li metal anode with dendrite-free Li deposition for Li metal-based rechargeable batteries.