急-锂单离子导电聚合物电解质的制备及其界面稳定性

Preparation and interfacial stability of single lithium-ion conductive polymer electrolytes

摘要:

以（对苯乙烯磺酸基）三氟甲基磺酰亚胺锂（LiSTFSI）、聚乙二醇甲醚甲基丙烯酸酯(PEGM)和甲基丙烯酸四氟丙酯（TFMA）、甲基丙烯酸八氟戊酯（OFMA）、甲基丙烯酸十二氟庚酯(DFMA)为单体，合成了三种锂单离子导电聚合物电解质隔膜。采用FTIR、SEM、EIS和LSV对隔膜进行了表征。研究表明，所合成的电解质膜具有较高的离子电导率（90 ℃，10-5 S/cm）、较宽的电化学稳定窗口（4.5 V）和高的锂离子迁移数（≈1）。将隔膜组装CR 2025扣式电池进行恒电位间歇滴定法（PITT）测试，结果显示电解质隔膜拥有较高的锂离子扩散系数（60 ℃，10-9 cm2/s）。经热处理后，电解质膜与锂金属的界面稳定性得到明显提升，X射线光电子能谱（XPS）测试表明这与含氟侧链基团在聚合物电解质的表面富集有关。

Abstract:

Three single lithium-ion conductive polymer electrolytes membrane were synthesized using lithium 4-styrenesulfonyl(trifluoromethylsulfonyl)imide (LiSTFSI), polyethylene glycol methyl methacrylate (PEGM), tetrafluoropropyl methacrylate (TFMA), octafluoropentyl methacrylate (OFMA) and dodecafluoroheptyl methacrylate (DFMA) as monomers. The membrane were characterized by FTIR, SEM, EIS and LSV. The results show that the synthesized electrolyte membrane have high ionic conductivity (90 ℃, 10-5 S/cm), wide electrochemical stability window (4.5 V) and high lithium-ion transference number (≈1). The button cell of membrane assembled CR 2025 was tested by constant potential intermittent titration (PITT). The results showed that the electrolyte membrane have a high lithium-ion diffusion coefficient (60 ℃, 10-9 cm2/s). After heat treatment, the interfacial stability between the electrolyte membrane and lithium metal was improved obviously. X-ray photoelectron spectroscopy shows that this was related to the enrichment of fluorine-containing side chain groups on the surface of the polymer electrolytes.