August 22, 2025
Journal Article

An Intrinsically Stable Electrolyte Enables Dense Magnesium Metal Anodes with Near-Unity Coulombic Efficiency

Abstract

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.

Published: August 22, 2025

Citation

Li C., R.D. Guha, S.D. House, J.D. Bazak, Y. Yu, L. Zhou, and K.R. Zavadil, et al. 2025. An Intrinsically Stable Electrolyte Enables Dense Magnesium Metal Anodes with Near-Unity Coulombic Efficiency. Joule 9, no. 2:101790. PNNL-SA-195248. doi:10.1016/j.joule.2024.11.007