聚酰亚胺嵌段聚乙二醇锂离子电池隔膜的制备及性能研究

Preparation and properties study of polyimide-polyethylene glycol block copolymers lithium ion battery separator

采用低温缩聚-化学亚胺化法合成了聚酰亚胺-聚乙二醇嵌段共聚物(PI-b-PEG),并利用相转化法制备了具有高耐热性能和离子传输性能的PI-b-PEG锂电池隔膜.将其性能与PI隔膜和商业Celgard 2325 PP膜进行了对比考察.结果表明,PI和PI-b-PEG隔膜在200℃可以保持尺寸稳定,具有优异的耐热性能.与商业PP膜相比,PI和PI-b-PEG隔膜表现出更高的孔隙率、吸液率、锂离子迁移数和离子电导率.PI-b-PEG隔膜离子电导率相对PI提升显著,常温下达到1.912 2 mS/cm.PI-b-PEG隔膜所组装的电池表现出良好的循环稳定性,以1 C的电流密度进行充放电,100次循环后容量仍然可以保持在137.6 mA·h/g.同时,PI-b-PEG隔膜电池表现出更好的倍率性能.

In this paper, polyimide-polyethylene glycol block copolymers(PI-b-PEG) were synthesized by the low temperature polycondensation-chemical imidation method, and PI-b-PEG lithium ion battery separators were prepared by phase inversion method, which had excellent thermal stability and ion transport performance. A seris of properties of PI-b-PEG separators were compared with the PI separators and the commercial Celgard 2325 PP film. The results showed that the PI and PI-b-PEG separators can maintain dimensional stability at 200 ℃ and had excellent thermal stability. Compared with commercial PP film, PI and PI-b-PEG separators exhibited higher porosity, liquid absorption rate, lithium ion migration number and ionic conductivity. The ionic conductivity of PI-b-PEG separator was significantly improved compared with PI, reaching 1.912 2 mS/cm at room temperature. The battery using PI-b-PEG separators exhibited excellent cycling stability, whose capacity was maintained at 137.6 mA·h/g after 100 cycles at a charge-discharge current density of 1 C at room temperature. The battery using PI-b-PEG separators exhibited better rate performance.