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Keywords:

  • battery separators;
  • electrospinning;
  • fibers;
  • nanocomposites, nanoparticles;
  • polyvinylidene fluoride;
  • SiO2 nanoparticles

ABSTRACT

SiO2/polyvinylidene fluoride (PVDF) composite nanofiber-coated polypropylene (PP) nonwoven membranes were prepared by electrospinning of SiO2/PVDF dispersions onto both sides of PP nonwovens. The goal of this study was to combine the good mechanical strength of PP nonwoven with the excellent electrochemical properties of SiO2/PVDF composite nanofibers to obtain a new high-performance separator. It was found that the addition of SiO2 nanoparticles played an important role in improving the overall performance of these nanofiber-coated nonwoven membranes. Among the membranes with various SiO2 contents, 15% SiO2/PVDF composite nanofiber-coated PP nonwoven membranes provided the highest ionic conductivity of 2.6 × 10−3 S cm−1 after being immersed in a liquid electrolyte, 1 mol L−1 lithium hexafluorophosphate in ethylene carbonate, dimethyl carbonate and diethyl carbonate. Compared with pure PVDF nanofiber-coated PP nonwoven membranes, SiO2/PVDF composite fiber-coated PP nonwoven membranes had greater liquid electrolyte uptake, higher electrochemical oxidation limit, and lower interfacial resistance with lithium. SiO2/PVDF composite fiber-coated PP nonwoven membrane separators were assembled into lithium/lithium iron phosphate cells and demonstrated high cell capacities and good cycling performance at room temperature. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1719–1726