Understanding and facilitating pure magnesium nucleation/growth electrodeposition behavior with ultrahigh Coulombic efficiency is complicated by the phenomenon of solid electrolyte interphase (SEI) formation in state-of-the-art, halogen-free magnesium electrolytes. Defining the electrolyte properties necessary to achieve ideal electrodeposition/stripping (E/S) thus remains elusive. Here, we reveal for the first time, rapid magnesium electrodeposition behavior that forms densely aligned, micron-sized thin platelets by establishing a dynamic bare magnesium/electrolyte interface during high-rate net plating. This effectively “SEI-free” interface allows facile magnesium diffusion and migration in stripping with near-unity E/S efficiency under demanding conditions over long-term cycling. The intrinsic electrolyte stability of the salt/solvent at the molecular level is the key to forming such an interface. The efficacy of the dynamic bare interface and an electrodeposited, free-standing magnesium anode is demonstrated in a high-areal-capacity full cell. These findings provide new design principles and fundamental understanding of interfacial chemistry in multivalent metal batteries.

中文翻译：

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动态裸机界面可实现 50 mAh cm−2 的可逆镁电沉积


由于最先进的无卤素镁电解质中固体电解质界面 （SEI） 形成现象，理解和促进具有超高库仑效率的纯镁成核/生长电沉积行为变得复杂。因此，定义实现理想电沉积/剥离 （E/S） 所需的电解质特性仍然难以捉摸。在这里，我们首次揭示了快速镁电沉积行为，通过在高速净电镀过程中建立动态裸露的镁/电解质界面，形成密集排列的微米级薄片。这种有效的“无 SEI”界面允许在长期循环的苛刻条件下以接近统一的 E/S 效率在汽提中轻松扩散和迁移镁。盐/溶剂在分子水平上的固有电解质稳定性是形成这种界面的关键。动态裸界面和电沉积的独立式镁阳极的功效在高面容量全电池中得到了证明。这些发现为多价金属电池中的界面化学提供了新的设计原则和基本理解。