全氟(2-丙氧基)丙酸聚乙二酯/LiTFSI电解质的制备及其性能

Preparation and properties of perfluoro(2-propoxy)polyethylene glycol propionate/LiTFSI electrolyte

以六氟环氧丙烷二聚体与聚乙二醇(PEG)为原料,三乙胺或碳酸钾为缚酸剂,制备了全氟(2-丙氧基)丙酸聚乙二酯(HFPO-PEG),与双三氟甲烷磺酸亚胺锂(LiTFSI)组合成锂离子电解质HFPO-PEG/LiTFSI。采用傅里叶变换红外光谱表征了电解质的结构,采用Zahner Zennium E型电化学工作站测试了电解质的阻抗、电化学稳定性窗口和计时电流。结果表明:以碳酸钾为缚酸剂,可以获得高产率的HFPO-PEG;HFPO-PEG/LiTFSI[锂盐含量为15%(w)]较PEG/LiTFSI具有更高的电化学稳定性窗口,达到3.5~3.7 V[vs.Li/Li^(+)(表示金属Li氧化成Li^(+))];当PEG链段为聚乙二醇单甲醚(mPEG),相对分子质量为200时,HFPO-mPEG200/LiTFSI的锂离子迁移数为0.75。

Hexafluoropropylene oxide dimer and polyethylene glycol(PEG)were used as raw materials,triethylamine or potassium carbonate as acid binding agents,to prepare perfluoro(2-propoxy)propionate polyethylene glycol ester(HFPO-PEG),which was configured with lithium bistrifluoromethanesulfonate(LiTFSI)to be a lithium-ion electrolyte,HFPO-PEG/LiTFSI.The structure of the product was characterized byFourier transform infrared spectroscope,and its impedance,electrochemical stability window and chronocurrent were tested by Zahner Zennium E electrochemical workstation.The results show that a high yield of HFPO-PEG can be obtained when potassium carbonate is used as an acid binding agent.HFPO-PEG/LiTFSI in which the mass fraction of lithium salt is 15%has a higher electrochemical stability window than PEG/LiTFSI,reaching 3.5-3.7 V(vs.Li/Li^(+)).The lithium-ion migration number of HFPO-mPEG200/LiTFSI is 0.75 when the PEG segment is polyethylene glycol monomethyl ether(mPEG)whose molecular weight is 200.