Alloying Strategies for Efficient Lithium–Metal Anodes: Bridging Phase Diagrams, Defect Engineering, and Interfacial Charge Redistribution

Lithium–metal anodes present significant potential for the advancement of next‐generation high‐energy‐density batteries. Nevertheless, their route to commercialization is obstructed by enduring challenges, such as dendrite growth, unstable solid‐electrolyte interphases (SEIs), and pronounced volume variations. Traditional approaches, including the use of electrolyte additives and artificial SEIs, typically tackle these problems in a piecemeal manner, lacking the ability to integrate interfacial, mechanical, and kinetic stability concerns. This review reconceptualizes lithium alloying strategies as multifunctional systems that incorporate secondary metals (e.g., Mg, Ag, Sb) into lithium matrices, facilitating simultaneous improvements in nucleation consistency, dendrite inhibition, and strain alleviation. Distinct from prior works, three original frameworks are pioneered: 1) phase diagram‐guided alloy design to correlate thermodynamic stability with electrochemical stressors; 2) defect engineering paradigms linking lattice defects to ion transport and stress redistribution; and 3) interfacial charge redistribution at lithium‐alloy boundaries to govern the nucleation and growth processes of lithium deposits. The review methodically analyzes alloying strategies from the perspectives of atomic mechanisms, material innovations, and system‐level integration. By synthesizing multiscale design principles, this work transitions the focus from empirical methods to strategically engineered lithium–metal batteries, aiding their evolution from laboratory settings to the global energy storage arena.