Suppressing lithium (Li) dendrite growth is a central issue for achieving stable Li metal batteries (LMBs). Here, we propose a binary alloy interface that consists of Ag inner nucleation cores and Zn outer diffusion shells through which a Li solubility gradient is created appropriately to enable simultaneous high lithiophilicity and stability. These merits provide the superior cycling stability of the as-generated Li-Ag-Zn electrode compared with the bare Li or Li-Ag counterparts, resulting in the long-term cycling stability of LMBs.