Micro‐Alloying Engineered Mg‐Gd‐Mn Negative Electrode With Synergistic Grain Refinement and Non‐Basal Texturing for Long‐Life and Dendrite‐Free Magnesium Batteries

Abstract The inhomogeneous plating/stripping behavior and parasitic reactions of Mg metal negative electrode pose significant challenges to achieve the long‐term stability of rechargeable magnesium batteries, severely limiting their practical implementation in energy storage systems. In this study, a synergistic micro‐alloying strategy is proposed involving Gd and Mn to engineer a novel ternary Mg‐Gd‐Mn alloy negative electrode with significantly enhanced electrochemical properties. The solid‐solution and grain‐boundary pinning effects induced by Gd/Mn co‐addition triggered substantial lattice distortion, effectively refining grain structures and non‐basal oriented grains. This unique microstructure enhances Mg 2+ diffusion kinetics, accelerates homogeneous dissolution of Mg, and enables spatially uniform nucleation deposition. Consequently, the micro‐alloyed Mg‐Gd‐Mn electrode exhibits highly reversible Mg plating/stripping behavior, achieving exceptional cycling stability exceeding 4000 h in symmetric cells with a cumulative areal capacity up to 1.6 Ah cm −2 at high current densities. The Mg‐Gd‐Mn||Mo 6 S 8 full cell delivers superior specific capacity (70.11 mAh g −1 at 1 C) and ultralong cycling stability (4200 cycles at 5 C). This work presents a novel multi‐element synergy alloying strategy for the rational design of high‐performance Mg negative electrodes, underscoring the critical role of microstructural and crystallographic engineering in unlocking the practical potential of Mg metal negative electrodes.