通过共混静电纺丝技术制备了不同混合比例的聚偏氟乙烯-六氟丙烯/聚间苯二甲酰间苯二胺(PVDF-HFP/PMIA)纳米纤维锂电隔膜,经热处理后进行性能测试。详细研究了PVDF-HFP和PMIA材料本身对隔膜性能和电池电化学性能的影响,并分析电池循环测试后隔膜的变化。结果表明:PVDF-HFP与电解液的接触角只有5.7°,对电解液的亲和性更好,能够提高电解液在纤维网络多孔结构中的可及性,从而提高了隔膜的吸液率;PMIA能够提高隔膜的热尺寸和纤维网络形态的稳定性。电池测试发现,PVDF-HFP∶PMIA=1∶4隔膜具有较宽的电化学稳定窗口和良好的界面结构,离子电导率1.42mS/cm,优于Celgard隔膜(0.61mS/cm);首次放电比容量中达到了145.4mAh/g,表现最好,倍率循环也优于Celgard隔膜。在拆解经多次循环测试的电池后发现,其他共混比例的隔膜中部分纤维发生弯曲或聚集,堵塞膜中的孔隙,使Li+无法通过或缓慢通过,导致电池无法继续循环使用。
Polyvinylidene fluoride-hexafluoropropylene/polymetaphenylene isophthalamide (PVDF-HFP/PMIA) nanofiber separators of Li-ion battery with different mixing ratios were prepared by blending electrospinning technology,and the performance was tested after heat treatment.The effects of PVDF-HFP and PMIA materials themselves on the performance of the separator and the electrochemical performance of the battery were studied in detail,and the change of the separator after the battery cycle test was analyzed.The research results shown that the contact angle between PVDF-HFP and the electrolyte was only 5.7°,and the affinity for the electrolyte was better,which can improve the accessibility of the electrolyte in the porous structure of the fiber network,thereby improving the liquid absorption rate of the separator.PMIA can improve the thermal size of the separator and the stability of the fiber network morphology.The battery test found that the PVDF-HFP∶PMIA=1∶4 separator had a wide electrochemical stability window and good interface structure.The ionic conductivity was 1.42mS/cm,which was better than the Celgard separator (0.61mS/cm).The ratio capacity of first discharge reached 145.4mAh/g,the best performance,and it was also better than the Celgard separator in the rate cycle.After dismantling the batteries that was tested for multiple cycles,it was found that some fibers in the separators with other blending ratios were bent or aggregated,blocking the pores in the membranes,so that Li+ could not pass or slowly pass through,resulting in the battery being unable to continue to be recycled.
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基金资助
北京服装学院创新团队建设计划(BIFTTD201904)
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