Rechargeable magnesium batteries (RMBs) are considered a highly promising energy storage system. However, the lack of low-cost and highly effective electrolytes severely hinders the development of RMBs. Herein, a tris(2,2,2-trifluoroethyl) borate (B(Otfe)₃) co-solvent is introduced into the magnesium-aluminum-chloride complex electrolyte. The electrophilic B(Otfe)₃ as an electron pair acceptor can react with the passivation layer to avoid the electrolytic conditioning process. The B(Otfe)₃-modified solvation structure with low desolvation energy increases the concentration of active cation, effectively improving the ionic conductivity and area current density. Meanwhile, the B(Otfe)₃-modified solvation ions with lower LUMO energy induce the formation of the B-F/B-O-containing and MgF₂-containing solid electrolyte interphase (SEI), reducing the interfacial transfer impedance. The prepared B(Otfe)₃/MgCl₂/AlCl₃ (BMA) electrolyte exhibits excellent electrochemical performance with low overpotential (∼122 mV), high average coulombic efficiency (CE) (∼98.2%) and long-term cycling stability (1000 h). Moreover, the BMA electrolyte shows good compatibility with Mo₆S₈ and CuS cathodes. The Mg|CuS full cell keeps a high specific capacity of 231 mAh g⁻¹ after 80 cycles at 56 mA g⁻¹, and the Mg|Mo₆S₈ cell operates 1000 cycles with an average CE of nearly 100%. This work provides an effective way to simultaneously improve the electrolyte solvation sheath and SEI structure for stable magnesium batteries.

可充电镁电池 (RMB) 被认为是一种非常有前途的储能系统。然而，缺乏低成本和高效的电解质严重阻碍了人民币的发展。在此，将三(2,2,2-三氟乙基)硼酸盐(B(Otfe) ₃ )共溶剂引入到镁-铝-氯化物复合电解质中。作为电子对受体的亲电子B(Otfe) ₃可以与钝化层反应以避免电解调理过程。B(Otfe) ₃修饰的低去溶剂能结构增加了活性阳离子的浓度，有效提高了离子电导率和面积电流密度。同时，B(Otfe) _{3具有较低 LUMO 能量的改性溶剂化离子诱导含 BF/BO 和含 MgF 2}的固体电解质界面 (SEI)的形成，从而降低界面转移阻抗。制备的 B(Otfe) ₃ /MgCl ₂ /AlCl ₃ (BMA) 电解质表现出优异的电化学性能，具有低过电位（~122 mV）、高平均库仑效率（CE）（~98.2%）和长期循环稳定性（1000 H）。此外，BMA 电解液与 Mo ₆ S ₈和 CuS 正极具有良好的相容性。Mg|CuS 全电池在 56 mA g ^{-1下循环 80 次后仍保持 231 mAh g -1}的高比容量，而 Mg|Mo ₆S ₈电池运行 1000 个循环，平均 CE 接近 100%。这项工作为同时改善稳定镁电池的电解质溶剂化鞘层和 SEI 结构提供了一种有效途径。