Ion transport restriction in mechanically strained separator membranes

John Cannarella, Craig B. Arnold

Research output: Contribution to journalArticle

70 Scopus citations

Abstract

We use AC impedance methods to investigate the effect of mechanical deformation on ion transport in commercial separator membranes and lithium-ion cells as a whole. A Bruggeman type power law relationship is found to provide an accurate correlation between porosity and tortuosity of deformed separators, which allows the impedance of a separator membrane to be predicted as a function of deformation. By using mechanical compression to vary the porosity of the separator membranes during impedance measurements it is possible to determine both the α and γ parameters from the modified Bruggeman relation for individual separator membranes. From impedance testing of compressed pouch cells it is found that separator deformation accounts for the majority of the transport restrictions arising from compressive stress in a lithium-ion cell. Finally, a charge state dependent increase in the impedance associated with charge transfer is observed with increasing cell compression.

Original languageEnglish (US)
Pages (from-to)149-155
Number of pages7
JournalJournal of Power Sources
Volume226
DOIs
StatePublished - Mar 15 2013

All Science Journal Classification (ASJC) codes

  • Renewable Energy, Sustainability and the Environment
  • Energy Engineering and Power Technology
  • Physical and Theoretical Chemistry
  • Electrical and Electronic Engineering

Keywords

  • Capacity fade
  • Lithium-ion battery
  • Mechanical stress
  • Power fade
  • Separator
  • Tortuosity

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