Epitaxial Electrocrystallization of Magnesium via Synergy of Magnesiophilic Interface, Lattice Matching, and Electrostatic Confinement

Rechargeable magnesium batteries are particularly advantageous for renewable energy storage systems. However, the inhomogeneous Mg electrodeposits greatly shorten their cycle life under practical conditions. Herein, the epitaxial electrocrystallization of Mg on a three-dimensional magnesiophilic host is implemented via the synergy of a magnesiophilic interface, lattice matching, and electrostatic confinement effects. The vertically aligned nickel hydroxide nanosheet arrays grown on carbon cloth (abbreviated as “Ni­(OH)2@CC”) have been delicately designed, which satisfy the essential prerequisite of a low lattice geometrical misfit with Mg (about 2.8%) to realize epitaxial electrocrystallization. Simultaneously, the ionic crystal nature of Ni­(OH)2 displays a periodic and hillock-like electrostatic potential field over its exposed facets, which can precisely capture and confine the reduced Mg0 species onto the local electron-enriched sites at the atomic level. The Ni­(OH)2@CC substrate undergoes sequential Mg-ion intercalation, underpotential deposition, and electrocrystallization processes, during which the uniform, lamellar Mg electrodeposits with a locked crystallographic orientation are formed. Under practical conditions (10 mA cm–2 and 10 mAh cm–2), the Ni­(OH)2@CC substrate exhibits stable Mg stripping/plating cycle performances over 600 h, 2 orders of magnitude longer than those of the pristine copper foil and carbon cloth substrates.

可充电镁电池在可再生能源储能系统中具备显著优势。然而，实际工况下不均匀的镁电沉积物会大幅缩短其循环寿命。本文中，研究人员通过亲镁界面、晶格匹配与静电限域效应的协同作用，实现了镁在三维亲镁载体上的外延电结晶过程。研究人员精心设计了生长于碳布上的垂直取向氢氧化镍纳米片阵列（缩写为“Ni(OH)₂@CC”），该载体与镁的晶格几何失配度极低（约2.8%），满足了实现外延电结晶的核心前提条件。与此同时，氢氧化镍作为离子晶体，在其暴露晶面上呈现出周期性的丘状静电势场，可在原子尺度下精准捕获并限域还原生成的Mg⁰物种至局部富电子位点。Ni(OH)₂@CC载体依次经历镁离子嵌入、欠电位沉积以及电结晶过程，最终形成具有固定晶体取向的均匀层状镁电沉积物。在实际工况（10 mA cm⁻²与10 mAh cm⁻²）下，Ni(OH)₂@CC载体可实现长达600小时以上的稳定镁剥离/镀覆循环性能，其循环寿命较原始铜箔与碳布载体提升两个数量级。