Electronic Localization Derived Excellent Stability of Li Metal Anode with Ultrathin Alloy

Lithium metal is an ideal anode for next‐generation high‐energy‐density batteries. However, lithium dendrite growth has impeded its commercial application. Herein, fabricating Li‐based ultrathin alloys with electronic localization and high surface work function via depositing Bi, Al, or Au metals on the surface of copper foil for in situ alloying with lithium is proposed. It is discovered that the electronic localization can induce self‐smoothing effect of Li ions, as a result, significantly suppressing the growth of dendritic lithium. Meanwhile, the high surface work function can effectively alleviate side reactions between the electrolyte and lithium. With the as‐obtained ultrathin alloys as anodes, excellent cycling performance is achieved. The half cells run stably after more than 120 cycles under high capacity of 4 mAh cm −2 . The S||Bi/Cu‐Li full cell delivers a specific capacity of 736 mAh g −1 after 200 cycles. This work provides a new strategy for fabricating long‐life and high‐capacity lithium batteries.