Facilely synthesized crosslinked gel polymer electrolytes for high-performance quasi-solid-state rechargeable magnesium batteries

Abstract

Gel polymer electrolytes (GPEs) combine the high ionic conductivity of liquid electrolytes with the structural flexibility of polymer matrices, presenting significant advantages for high-safety, flexible rechargeable magnesium batteries. However, their development has been hindered by limited research and an incomplete understanding of the interactions among ions, anions, plasticizers, and the polymer matrix. In this study, we employ a facile one-step in situ Lewis acid–base reaction to synthesize a magnesium borohydride–magnesium chloride–polyethylene glycol composite gel polymer electrolyte supported on glass fiber (MBC–PEG@GF CGPE). This CGPE exhibits outstanding thermal stability, high ionic conductivity, a remarkable Mg²⁺ transference number, and excellent compatibility with Mg metal anodes. When paired with a Mo₆S₈ cathode, the assembled pouch cells demonstrate superior performance across a wide temperature range and maintain high safety under rigorous conditions, highlighting their potential for extreme applications, flexible devices, and large-scale deployment. Additionally, this work offers a comprehensive analysis of the coordination environment of Mg²⁺ within the CGPE and its influence on the bulk properties of the electrolyte. These findings provide valuable insights into the design and optimization of advanced gel polymer electrolytes for quasi-solid-state rechargeable magnesium batteries, paving the way for their integration into next-generation energy storage technologies.