Iodic acid (HIO3) was exploited as the effective source to build an artificial solid-electrolyte interphase (SEI) on the surface of Li anode. On one hand, HIO3 is a weak solid-state acid and can be easily handled to remove most ion-insulating residues like Li2CO3 and/or LiOH from the pristine Li surface; on the other hand, both the products of LiI and LiIO3 resulted from the chemical reactions between Li metal and HIO3 are reported to be the ion-conductive components. As a result, the lower voltage polarization and impedance, longer cycling lifetime and higher Coulombic efficiency have been successfully achieved in the HIO3-treated Li-Li and Li-Cu cells. By further using the HIO3-treated Li anode into practical Li-S batteries, the impressive results also have been obtained, with average discharge capacities of 719 mAh g-1 for 200 cycles (0.2 C) and 506 mAh g-1 for 500 cycles (0.5 C), which were better than the Li-S batteries using the pristine Li anode (552 and 401 mAh g-1, respectively) under the same conditions.