Composition ratio-dependent structural evolution of SiO2/ poly(vinylidene fluoride-hexafluoropropylene)-coated poly(ethylene terephthalate) nonwoven composite separators for lithium-ion batteries

Hyun Seok Jeong, Eun Sun Choi, Sang Young Lee

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49 Citations (Scopus)

Abstract

We demonstrate a facile approach for the fabrication of new silica (SiO2) nanoparticles/polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP)-coated polyethylene terephthalate (PET) nonwoven composite separators for use in lithium-ion batteries. By varying the SiO2/PVdF-HFP composition ratio, we can fine-tune the porous structure of the composite separators. At a low SiO2/PVdF-HFP ratio, a nonporous structure featuring the PVdF-HFP matrix and SiO2 domains is obtained. By contrast, an unusual porous structure (i.e., highly-percolated interstitial voids formed between close-packed SiO2 nanoparticles) is developed at a high SiO2/PVdF-HFP ratio, where PVdF-HFP serves as a binder to interconnect SiO2 powders. This drastic change in the morphology of the composite separators is further confirmed by observing their air permeability and ionic conductivity. Meanwhile, a PET nonwoven is employed as a mechanical substrate to suppress thermal shrinkage of the composite separators. On the basis of morphological characterization, the effects of the composition ratio-dependent structural evolution of the composite separators on the electrochemical performance of cells are investigated. Notably, the composite separator fabricated from a composition ratio of SiO2/PVdF-HFP = 90/10 (wt%/wt%) provides superior cell performance owing to a well-tailored microporous structure, as compared to a commercialized polyethylene (PE) separator.

Original languageEnglish
Pages (from-to)317-322
Number of pages6
JournalElectrochimica Acta
Volume86
DOIs
Publication statusPublished - 2012 Dec 30

Bibliographical note

Funding Information:
This work was supported by the National Research Foundation of Korea Grant funded by the Korean Government (MEST) ( NRF-2009-C1AAA001-2009-0093307 ). This work was also supported by Energy Efficiency and Resources R&D program (20112010100150) under the Ministry of Knowledge Economy, Republic of Korea.

All Science Journal Classification (ASJC) codes

  • Chemical Engineering(all)
  • Electrochemistry

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