High?Voltage Aqueous Mg?Ion Batteries Enabled by Solvation Structure Reorganization

Herein, an eco-friendly and high safety aqueous Mg-ion electrolyte (AME) with a wide electrochemical stability window (ESW) ?3.7 V, containing polyethylene glycol (PEG) low-concentration salt (0.8 m Mg(TFSI)2), is proposed by solvation structure reorganization of AME. The PEG agent significantly alters the Mg2+ hydrogen bonds network AMEs forms direct coordination TFSI-, thus enhancing physicochemical properties electrolytes. As exemplary material, V2O5 nanowires are tested in this new AME exhibit initial discharge/charge capacity 359/326 mAh g-1 retention 80% after 100 cycles. crystalline ?-V2O5 shows two 2-phase transition processes formation ?-Mg0.6V2O5 Mg-rich MgxV2O5 (x ?1.0) during first discharge. phase formed through intercalation at room temperature for time observed via XRD. Meanwhile, cathode interphase (CEI) batteries revealed time. MgF2 originating from decomposition TFSI- identified as dominant component. This work offers approach designing high-safety, low-cost, eco-friendly, large ESW electrolytes practical novel multivalent batteries.