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Title: Failure analysis of pinch-torsion tests as a thermal runaway risk evaluation method of Li-Ion Cells

Recently a pinch-torsion test is developed for safety testing of Li-ion batteries (Ren et al., J. Power Source, 2013). It has been demonstrated that this test can generate small internal short-circuit spots in the separator in a controllable and repeatable manner. In the current research, the failure mechanism is examined by numerical simulations and comparisons to experimental observations. Finite element models are developed to evaluate the deformation of the separators under both pure pinch and pinch-torsion loading conditions. It is discovered that the addition of the torsion component significantly increased the maximum principal strain, which is believed to induce the internal short circuit. In addition, the applied load in the pinch-torsion test is significantly less than in the pure pinch test, thus dramatically improving the applicability of this method to ultra-thick batteries which otherwise require heavy load in excess of machine capability. It is further found that the separator failure is achieved in the early stage of torsion (within a few degree of rotation). Effect of coefficient of friction on the maximum principal strain is also examined.
 [1] ;  [2] ;  [3] ;  [4] ;  [4]
  1. University of Tennessee, Knoxville (UTK)
  2. Florida State University, Tallahassee
  3. Temple University
  4. ORNL
Publication Date:
OSTI Identifier:
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Power Sources; Journal Volume: 256; Journal Issue: C
Research Org:
Oak Ridge National Laboratory (ORNL)
Sponsoring Org:
SC USDOE - Office of Science (SC); EE USDOE - Office of Energy Efficiency and Renewable Energy (EE)
Country of Publication:
United States
Li-ion battery; finite element analysis; pinch-torsion test; fracture; internal short circuit