From solvation regulation to interfacial reconstruction: Unveiling the role of amine and phosphate ester additives in Mg batteries

Abstract

Rechargeable magnesium batteries (RMBs) promise high safety and volumetric energy density, yet their development is limited by the lack of electrolytes enabling reversible Mg anodes.Functional additives provide an effective route to regulate electrolyte structures and interfacial chemistry. Among them, amine and phosphate ester additives, as representative N and O-donor species, exhibit distinct but not yet fully understood roles. This review establishes a unified framework bridging solvation regulation and interfacial reconstruction. The competitive Mg 2+ solvation governs the ion pairing configurations, thereby dictating the desolvation and interfacial reactivity. Additive promoted interphase formation is further elucidated through suppressed electrolyte decomposition, construction of conductive SEI components, and solvation-mediated interfacial evolution. Collectively, this review establishes a unified framework in which electrolyte additives act as active molecular regulators that simultaneously tune coordination chemistry, ion association, and interfacial reaction pathways. The insights derived herein highlight key design principles, including modulating of Mg 2+ solvation, controlling of ion-pairing configurations, and programming of interphase chemistry via selective additive participation. These understandings are expected to guide the rational development of next-generation Mg electrolytes toward highly reversible and practically viable RMBs systems.