Electrochemical plating/stripping reversibility and characterizations of the Na metal plating on Cu in different electrolytes. a) Voltage‐time profiles of Na||Na symmetric cells and b) Na plating/stripping Columbic efficiency (CE) of cycling performance in Na||Cu asymmetric cells at 1.0 mA cm⁻² with a capacity of 1.0 mAh cm⁻². SEM images of Na plating on the Cu with c) WSAS, (d) SSAD, and e) Carbonate‐based electrolytes after 50 cycles. f) C 1s XPS‐spectra of SEI on the cycled Cu surfaces form the Na||Cu cells and g) corresponding atomic ratios of different elements in the SEI.