POSS-(PMMA46)8浸渍涂覆商业PP隔膜的结构与性能

为了提高锂离子电池的安全性能,降低其界面阻抗,选用既具有优异耐热性能又与聚合物有良好相容性的POSS杂化聚甲基丙烯酸甲酯(POSS-(PMMA 46 ) 8)作为改性剂,通过在商业聚丙烯(PP)隔膜上浸渍POSS-(PMMA 46 ) 8制备改性商用PP隔膜,分析隔膜的力学性能、热收缩性能、界面性能、离子电导率及电化学性能。结果表明:当POSS-(PMMA 46 ) 8质量分数为40%时,复合膜的孔丰富均一,润湿性最佳,拉伸强度是未改性前的5.34倍,且在160℃/1h下具有较高的热稳定性。此复合膜电导率为1.35×10 -3 S/cm,与电极的界面阻抗由原来的743Ω降为152Ω;Li/改性隔膜/LiFePO 4扣式电池的充放电循环稳定性较好,低倍率下的电池容量与商业PP隔膜相当。

Structure and properties of POSS-(PMMA46)8 impregnated commercial polypropylene separator

In order to improve the safety and reduce interface impedance of lithium-ion batteries, the star-shaped polyhedral POSS-poly(methyl methacrylate)(POSS-(PMMA 46 ) 8), which has both excellent heat resistance and good compatibility with the polymer material, was selected as a modifier to modify the separator of commercial polypropylene (PP) by the method of impregnation. The micromorphology of the composite separator was studied by scanning electron microscope (SEM). The mechanical property of the separator was measured by a tensile tester. The thermal stability of the separator was studied at a high temperature. The wettability of the separator was tested by a contact angle tester. The AC impedance was used to obtain the bulk impedance of the composite separator and then its ionic conductivity was studied. The electrochemical stability of the separator was measured by linear sweep voltammetry (LSV). The results show that when the mass fraction of POSS-(PMMA 46 ) 8 is 40%, the pore distribution of the composite membrane is homogeneous, and the wettability is the best. The tensile strength is 5.34 times that of the original film, and the thermo-stability is ideal at 160℃/1h. The conductivity of the composite membrane is 1.35×10 -3 S/cm. The interface resistance between the composite separator and the electrode is reduced from 743Ω to 152Ω, and which is 79.5% higher than that of the original film;for Li/Separator/LiFePO 4 cell, the charge-discharge cycling stability is better and the battery capacity at low magnification is comparable to commercial PP separator.