阻燃凝胶聚合物电解质的制备及其性能研究

Preparation and performance of a flame-retardant gel polymer electrolyte

本工作采用原位聚合工艺制备阻燃凝胶聚合物电解质,将1,1,2,2-四氟乙基-2,2,3,3-四氟丙基醚(HFE)引入电解质体系中,在提高电解质的阻燃性能的同时,还可以通过调节多硫化物的溶解程度来抑制锂硫电池的“穿梭效应”。对比未添加HFE(HFE-0)和添加不同含量HFE的电解质的阻燃性能和电化学性能发现,DOL、DME和HFE体积比为1∶0.5∶0.5时(HFE-0.5)凝胶聚合物电解质具有最优的阻燃性能和电化学性能。通过扫描电子显微镜(SEM)和电化学技术等表征测试手段,对比分析了使用HFE-0和HFE-0.5电解质的锂硫电池和磷酸铁锂电池的电化学性能及其相应的锂负极在循环后的表面形貌,结果表明,使用HFE-0.5电解质的锂硫电池在0.1 C的倍率下循环100圈后仍可保持706 mAh/g的放电比容量,容量保持率达到84.59%,循环性能明显优于未添加HFE的电解质。此外,使用HFE-0.5电解质的磷酸铁锂电池在0.2 C的倍率下循环110圈后的放电比容量仍可达到117.2 mAh/g,说明所制备的凝胶聚合物电解质也可适用于磷酸铁锂电池体系。本文设计的阻燃凝胶聚合物电解质有助于推动锂硫电池的发展和应用。

In this work,a flame-retardant gel polymer electrolyte was prepared using an in situ polymerization process.We introduced 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether(HFE)into an electrolyte system to improve the flame retardancy of the electrolyte.HFE can also inhibit the shuttle effect in lithium-sulfur batteries by adjusting the solubility of polysulfides.By comparing the flame retardancy and electrochemical performance tests of electrolytes without HFE(HFE-0)and electrolytes with different HFE contents,it was found that when the volume ratio of DOL,DME,and HFE was 1∶0.5∶0.5(HFE-0.5),respectively,the gel polymer electrolyte demonstrated the best flame retardancy and electrochemical performance.Scanning electron microscopy(SEM)and electrochemical tests were performed to analyze and compare the electrochemical properties and lithium anode surface morphologies of lithium-sulfur and lithium-iron-phosphate batteries using HFE-0 and HFE-0.5 electrolytes after cycling.The results show that the lithium-sulfur battery with the HFE-0.5 electrolyte can maintain a specific discharge capacity of 706 mAh/g after 100 cycles with an 84.5%capacity retention rate at 0.1 C,and the cycling performance is significantly better than that of the electrolyte without HFE.In addition,the specific discharge capacity of the lithium-iron-phosphate battery with the HFE-0.5 electrolyte reached 117.2 mAh/g after 110 cycles at 0.2 C,indicating that the prepared gel polymer electrolyte can also be applied in these batteries.The designed flame-retardant gel polymer electrolytes with good electrochemical performances are useful for promoting the development and application of lithium-sulfur batteries.