沸石/聚乙烯醇涂覆改性聚丙烯隔膜及其性能研究

Performance research on modification of polypropylene separator for lithium ion batteries by zeolite/polyvinyl alcohol coating

为了改善商业聚丙烯(PP)隔膜与电解液浸润性差和热尺寸稳定性不佳的问题,采用浸涂法制备了沸石/聚乙烯醇涂覆PP隔膜。通过扫描电子显微镜(SEM)、电池测试系统和电化学工作站等表征手段研究了改性隔膜的表面形貌、孔隙率、吸液率、热稳定性以及电化学性能,并与PP隔膜进行了性能对比。结果表明,改性后的PP隔膜孔隙率从38.4%提升到41.2%,吸液率从108.4%增加到181.1%,170℃下的热收缩率从58%降至23%。与PP隔膜相比,改性隔膜的循环性和稳定性得到了提高。界面阻抗从88Ω降为61Ω,离子电导率从0.58 mS/cm增加到0.75 mS/cm。沸石/聚乙烯醇涂层是改善PP隔膜电化学性能和热稳定性的有效方法,能够提高锂电池的循环性和安全性。

To improve the electrolyte wettability and thermal dimensional stability of the commercial polypropylene(PP)separators for lithium ion batteries,zeolite/polyvinyl alcohol coated PP separators have been prepared by dip-coating method.The morphology,porosity,hydrophilicity,electrolyte uptake,thermal stability and electrochemical properties of the modified PP separators were studied by scanning electron microscopy(SEM),battery test system and electrochemical workstation.Compared with the commercial PP separator,it showed that the porosity increased from 38.4%to 41.2%,and the electrolyte uptake increased from 108.4%to 181.1%,but the heat shrinkage reduced from 58%to 23%at 170℃after modification.Compared with commercial PP separator,the electrochemical performance and stability of the modified PP separator are also improved.The interfacial impedance was reduced from 88Ωto 61Ω,and the ionic conductivity increased from 0.58 mS/cm to 0.75 mS/cm.The results show that zeolite/polyvinyl alcohol coating is an effective way to improve the electrochemical properties and thermal stability of PP separator,and can improve the cyclicality and safety of lithium batteries.