A polymer-based magnesium (Mg) electrolyte is vital for boosting the development of high-safety and flexible Mg batteries by virtue of its enormous advantages, such as significantly improved safety, potentially high energy density, ease of fabrication, and structural flexibility. Herein, a novel polytetrahydrofuran-borate-based gel polymer electrolyte coupling with glass fiber is synthesized via an in situ crosslinking reaction of magnesium borohydride [Mg(BH 4 ) 2 ] and hydroxyl-terminated polytetrahydrofuran. This gel polymer electrolyte exhibits reversible Mg plating/stripping performance, high Mg-ion conductivity, and remarkable Mg-ion transfer number. The Mo 6 S 8 /Mg batteries assembled with this gel polymer electrolyte not only work well at wide temperature range (−20 to 60 °C) but also display unprecedented improvements in safety issues without suffering from internal short-circuit failure even after a cutting test. This in situ crosslinking approach toward exploiting the Mg-polymer electrolyte provides a promising strategy for achieving large-scale application of Mg-metal batteries.
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- in situ crosslinking reaction
- magnesium batteries
- polymer electrolytes