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

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-SO₃Li）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-SO₃Li/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-SO₃Li/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-SO₃Li/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5.5 V提高至5.8 V，界面阻抗从360 Ω降低至315 Ω，离子电导率从2.416×10^-3 S/cm提高至3.672×10^-3 S/cm。

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

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 V to 5.8 V, the bulk resistance decreases from 360 Ω to 315 Ω, and the ion conductivity increases from 2.416×10^-3 S/cm to 3.672×10^-3 S/cm.