Magnesium/sulfur battery (Mg/S) has recently received wide attention due to its high theoretical energy density (3,260 Wh/L) and low cost. To further improve its safety and flexibility, developing a polymer electrolyte that can be compatible with both electrophilic S and Mg is critical. Here, we report a magnesium chloride-(fluorinated tetraethylene glycolic)borate (MgCl-FTGB) based non-nucleophilic, gel-type polymer electrolyte for Mg/S battery via a facile synthetic method through commercially available reagents. This electrolyte coupled with glass fiber allows reversible Mg deposition/dissolution (100% coulombic efficiency) with low polarization (500 µA/cm², 300/300 mV), and shows a wide electrochemical window of 4.8 V (vs. Mg/Mg²⁺). Mg/S battery assembled with this electrolyte can cycle over 50 times with a high specific discharge capacity retention of over 1,100 mAh/g.

镁/硫电池（Mg / S）由于其较高的理论能量密度（3,260 Wh / L）和低成本而受到了广泛关注。为了进一步提高其安全性和柔韧性，开发能够与亲电性S和Mg相容的聚合物电解质至关重要。在这里，我们通过市售试剂通过简便的合成方法报告了一种用于Mg / S电池的氯化镁-（氟化四乙二醇）硼酸盐（MgCl-FTGB）基非亲核凝胶型聚合物电解质。这种电解质加上玻璃纤维允许可逆镁沉积/溶解（100％库仑效率）低的极化（500μA/厘米²，300/300毫伏）和节目4.8 V的电化学窗口宽（相对于镁/镁^{2 +}）。装有这种电解质的Mg / S电池可以循环50次以上，并保持超过1,100 mAh / g的高比放电容量。