静电纺聚乙烯-乙烯醇磺酸锂/聚酰亚胺锂离子电池隔膜复合材料的电化学性能

Electrochemical properties of lithium ethylene-vinyl alcohol copolymer sulfate/polyimide Li-ion battery separator composite by electrospinning

以3,3’,4,4’-二苯甲酮四羧酸二酐和4,4-二氨基二苯醚为原料合成聚酰胺酸(PAA)纺丝液,通过高压静电纺丝和热亚胺化制备聚酰亚胺(PI)纤维膜,然后将聚乙烯-乙烯醇磺酸锂(EVOH-SO_3Li)以高压静电纺丝和加热加压的方式覆盖在PI纤维膜表面,制备EVOH-SO_3Li/PI锂离子电池隔膜复合材料。通过FTIR、SEM、万能拉伸试验仪、接触角测试仪和IM6型电化学工作站对EVOH-SO_3Li/PI锂离子电池隔膜复合材料的性能进行测试与表征。结果表明:EVOH-SO_3Li/PI锂离子电池隔膜复合材料具有较清晰的三维网状结构,与PI隔膜相比,纤维间粘连现象明显增加,在降低孔隙率同时,吸液率和拉伸强度分别提高至521%和12.83 MPa,并表现出较好的热收缩稳定性、高温闭孔性能和电化学性能。其中电化学稳定窗口从5.5V提高至5.8V,界面阻抗从360Ω降低至315Ω,离子电导率从2.416×10^(-3) S/cm提高至3.672×10^(-3) S/cm。

Polyamic acid（PAA）spinning solution was fabricated by using benzophenone-3,3＇,4,4＇-tetracarboxylic dianhydride and 4,4-diaminodiphenyl ether as raw materials,and the polyimide（PI）fiber membranes were prepared by high-pressure electrospinning and thermal imidization.Then,lithium ethylene-vinyl alcohol copolymer sulfate（EVOH-SO3Li）/PI li-ion battery separator composites were prepared by introduction of EVOH-SO3Li fiber on both sides of PI membranes surface through high-pressure electrospinning and heating pressure treatment.The performance of EVOH-SO3Li/PI li-ion battery separator composite was characterized by FTIR,SEM,universal tensile tester,contact angle meter and IM6 electrochemical workstation.The results show that EVOH-SO3Li/PI separator has a clear three-dimensional network structure.Compared with PI separator,the absorption rate and tensile strength of modified EVOH-SO3Li/PI separator composites increase to 521% and 12.83 MPa although the porosity reduces.The excellent thermal shrinkage rate,closed-cell at high temperature and electrochemical performance were exhibited.Then,the electrochemical window increases from 5.5 Vto 5.8 V,the bulk resistance decreases from 360Ω to 315Ω,and the ion conductivity increases from 2.416×10^-3S/cm to 3.672×10^-3S/cm.