聚偏氟乙烯-沸石复合锂电隔膜的制备及性能

针对传统聚烯烃类锂离子电池隔膜的耐温性差和电解液亲和性差的问题,本实验以微孔沸石纳米粒子和聚偏氟乙烯树脂(PVDF)为主要原料,通过相转化法制备了综合性能优异的沸石/PVDF复合锂电隔膜。结果表明:与商用聚乙烯(PE)膜相比,所制备的沸石/PVDF复合隔膜具有更加发达的孔道结构,其孔隙率超过70%,约为PE膜的2倍。沸石/PVDF复合膜的耐高温性和电解液润湿性明显优于PE膜和纯PVDF膜,经过160℃、0.5h的高温处理后,复合膜的热收缩率仅为5%,而PE膜已完全融化,收缩率达到100%,PVDF膜收缩率超过50%;沸石/PVDF复合膜的电解液接触角仅为7.4°,而PE膜和PVDF膜的接触角高达42.5°和31.7°。受益于丰富的孔道结构和良好的电解液吸收/保持能力,沸石/PVDF复合膜所装配锂离子电池的倍率放电容量高于PE膜,同时,该复合膜装配电池的循环性能也优于传统聚乙烃隔膜。

Preparation and performances of PVDF-zeolite composite separator for lithium-ion batteries

To improve the thermal stability and electrolyte wettability of polyolefin-based separators, a high performance organic-inorganic composite separator was prepared by a phase inversion process using microporous zeolite nano-particles and polyvinylidene fluoride (PVDF).The results show that compared with the polyolefin-based separator(PE), the zeolite/PVDF composite separator exhibits well-developed microstructure, superior thermal resistance and excellent liquid electrolyte wettability, for example the porosity of the present separator is over 70% which is about one time higher than that of PE separator, and the zeolite/PVDF composite separator exhibits exce-llent thermal stabilitywith area shrinkage of 5% after the heat treatment at 160℃ for 0.5 h, while PE separator and PVDF separator show 100% and 50% thermal shrinkage under the same condition respectively.Moreover, the electrolyte contact angle of zeolite/PVDF composite separator is about 7.4°, while those of PE separator and PVDF separator are about 42.5° and 31.7°.Based on the above advantages, zeolite/PVDF composite separator exhibits better electrochemical performances, such as the C-rate discharge capability and cycling performance, as compared to the commercialized PE separator.