Rechargeable magnesium batteries (RMBs) remain limited by interfacial instability under large areal capacity and current density, where dissolution of solid-electrolyte interphase (SEI) components remains underexplored. Here, we identify solvation-driven dissolution of organic interphase species as a key origin of rapid cell failure and address it through a Si–O molecular engineering strategy using tris(trimethylsilyl) phosphate (TMSP). TMSP sterically regulates the Mg2+ solvation, weakens solvent coordination, and increases anion participation, thereby reducing unstable solvent-derived organics. Meanwhile, its preferential interfacial decomposition yields silicate/silicide and dissolution-resistant organosilicon species, forming a stronger, smoother, and more dissolution-resistant SEI. The optimized electrolyte enables reversible Mg||Mg cycling for over 3400 h at 20 mA cm–2 and 4 mAh cm–2, while maintaining a wide operating-temperature range from −20 to 55 °C and broad cathode compatibility. This work reveals SEI dissolution as a critical degradation pathway and provides a cost-effective electrolyte design strategy for durable RMBs.
Fan et al. (Thu,) studied this question.