Single-solvent electrolyte system for rechargeable magnesium batteries

Rechargeable magnesium metal batteries (RMBs) represent a promising sustainable energy storage technology, complementary to lithium-ion and sodium-ion batteries due to their superior volumetric energy density, cost-effectiveness, and safety. However, their widespread adoption is hindered by limited electrolyte options due to the formation of Mg ion-insulating surface films that cannot behave as solid-electrolyte-interphases. Here, after considering the binding affinity with Mg²⁺ and steric hindrance, we report a single-solvent system based on commercial aminoacetaldehyde dimethyl acetal (ADMA). Our system effectively forms a Mg ion-conducting interphase and enhances the Mg plating-stripping efficiency, without severe corrosion. The average Coulombic efficiency is 97.3% over 500 hours upon galvanostatic cycling in Mg‖stainless steel cells at cycling conditions of 0.5 mA cm⁻² and 0.5 mAh cm⁻², along with capacity retention of 90.3% and 99.2% for 250 and 300 cycles in Mg‖Mo₆S₈ and Mg‖Tellurium full-cells, respectively. This study indicates that high-performance practical RMBs are achievable through solvation structure engineering with commercially available solvents and salts.