is primarily attributed to uncontrolled Li dendrite growth, which inevitably occurs on the Li surface during repeated plating/ stripping processes. Li dendrite-growth leads to battery performance failure and thermal runaway, causing a catastrophic safety failure accompanied by fi re and smoke. With the emergence of Li-ion batteries (LIBs) based on the Li intercalating anode materials represented by carbonaceous anodes in the early 1990s, enthusiasm for developing commercial Li metal secondary batteries has largely diminished. [ 3,[8][9][10] Recently, the need for electric vehicles (EVs) and energy storage systems (ESSs) that require a higher level energy density from electric energy sources than that available from commercialized LIBs has sparked renewed interest in Li metal anodes. Rechargeable batteries using Li metal anodes such as Li/air [11][12][13] or Li/sulfur [14][15][16] batteries are attracting increasing attention as possible alternatives, with many researchers devoting intense efforts to realize these systems. For successful implementation of such nextgeneration battery systems beyond LIBs, signifi cant challenges remain for each battery constituent, including Li metal anodes, cathodes, electrolytes, and battery system design. Above all, harmonious improvement in each fi eld is a prerequisite. Li metal stabilization is a burdensome task because of the well-known diffi culties encountered during the long history of Li battery research and the resultant failure to realize the use of Li metal in a commercialized rechargeable battery system during the last four decades.During the fi rst charging process, the higher cathodic potential compared with the Li ion reduction leads to reductive decomposition of electrolytes, including organic solvents and Li salt on Li metal, and the formation of electrically insulating but ionically conducting protective fi lm called surface electrolyte interphase (or interface, SEI). [ 8,[17][18][19] This passive layer ideally permits Li ion migration and prevents further electrolyte decomposition, enabling stable cycle performance of LIBs in the subsequent cycles. As discussed extensively, [ 18,[20][21][22][23] SEI is understood to be a highly complicated Li ion conducting layer consisting of many different decomposed products with inorganic and organic components, such as Li 2 CO 3 , Li 2 O, LiCO 2 R, LiF, and Li alkoxides. SEI inevitably possesses lateral and vertical non-uniformity, which leads to uneven Li ion conduction. During the charging process, Li ions moving through SEI Repressing uncontrolled lithium (Li) dendrite growth is the top priority for enabling the reliable use of Li metal secondary batteries. On the other hand, the technique controlling the metal plating behavior during metal plating indeed has been considered very diffi cult to achieve. For instance, how can one plate metal ions on the favored selected region during plating? The present study describes how to achieve this goal, i.e., dendrite-free Li deposition, by mechanical surface modifi cation using ...
