Abstract
The practical development of rechargeable magnesium batteries is fundamentally limited by anode passivation, electrolyte-induced corrosion, and sluggish interfacial Mg(2+) transport. Herein, we develop a universal electrolyte design strategy that exploits the synergy between halides and phosphate esters to address these long-standing challenges. Typically, the incorporation of SiBr(4) and tris(trimethylsilyl) phosphate (TMSP) extends the electrochemical stability window of the electrolyte from 2.75 to 3.94 V and reconstructs the solvation environment toward bis(trifluoromethanesulfonyl)imide (TFSI(-)) and TMSP-dominated coordination, significantly lowering the Mg(2+) desolvation barrier. Preferential reduction of SiBr(4) and TMSP yields a cross-linked, inorganic-rich interphase comprising Mg(3)(PO(4))(2), MgSiO(3), and MgBr(2), which enables fast Mg(2+) transport and effectively suppresses parasitic reactions. Meanwhile, Mg(3)(PO(4))(2) and MgSiO(3) within the interphase serve as robust scaffolds that immobilize soluble MgBr(2), further reinforcing interfacial stability. Besides, the electron-rich P[double bond, length as m-dash]O groups in TMSP further stabilize reactive SiBr(3) (+) intermediates, thereby preventing electrolyte acidification and corrosion. Consequently, Mg‖Mg symmetric cells cycle stably for 1800 h with a low overpotential of 0.14 V. Mg‖Mo cells reach a peak coulombic efficiency of 99.97% at 3.4 V after the activation process. Full cells with a Mo(6)S(8) cathode deliver a capacity of 80 mAh g(-1) with only 0.08% fading over 500 cycles, and Mg‖polyaniline-intercalated V(2)O(5) (PANI-V(2)O(5)) cells achieve 160 mAh g(-1) at a cut-off voltage of 2.6 V. This synergistic regulation concept is generalizable to other halides and phosphate esters, providing new mechanistic insights and a general framework for designing stable electrolytes for multivalent batteries.