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Title: Crashworthiness Models for Automotive Batteries

Abstract

Safety is a key element of any device designed to store energy, particularly of electrochemical batteries, which convert energy of chemical reactions to electrical energy. Safety considerations are especially important when applied to large automotive batteries designed for propulsion of electric vehicles (EV). The high amount of energy stored in EV battery packs translates to higher probability of fire in case of severe deformation of battery compartment due to automotive crash or impact caused by road debris. While such demand for safety has resulted in heavier protection of battery enclosure, the mechanisms leading to internal short circuit due to deformation of the battery are not well understood even on the level of a single electrochemical cell. Moreover, not all internal shorts result in thermal runaway, and thus a criterion for catastrophic failure needs to be developed. This report summarizes the effort to pinpoint the critical deformation necessary to trigger a short via experimental study on large format automotive Li-ion cells subjected to large deformations as those occurring in deformation of battery module or pack. Mechanical properties of cell components were determined via experimental testing and served as input for constitutive models of Finite Element (FE) analysis. It has been rationalizedmore » that long-range stress fields occurring in spherical indentation of battery modules would trigger different deformation and failure scenarios compared to indentation of a single cell supported by a rigid flat surface. In order to investigate large deformations characteristic of battery module, a custom experimental set up has been built where the pouch cell was deformed against a compliant backing, which was represented by a ballistic clay. Experiments were also conducted on deformation of stacks of 10 pouch cells, - configuration representing half-module in Ford Focus EV battery pack without cooling plates and structural components. Comparison of the results shows promise for the compliant backing setup for safety evaluation of battery cells under more realistic conditions compared to indentation of single cell against undeformable backing where compression and electrode particle penetration through separator could be the major mechanism for short circuit.« less

Authors:
 [1];  [1];  [1];  [1];  [1];  [1];  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science & Technology Division and Computational Sciences and Engineering Division
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE; USDOT National Highway Traffic Safety Administration (NHTSA)
OSTI Identifier:
1435250
Report Number(s):
ORNL/TM-2018/753
DOE Contract Number:  
AC05-00OR22725
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE; 42 ENGINEERING

Citation Formats

Kalnaus, Sergiy, Wang, Hsin, Simunovic, Srdjan, Kumar, Abhishek, Gorti, Sarma B., Allu, Srikanth, and Turner, John A. Crashworthiness Models for Automotive Batteries. United States: N. p., 2018. Web. doi:10.2172/1435250.
Kalnaus, Sergiy, Wang, Hsin, Simunovic, Srdjan, Kumar, Abhishek, Gorti, Sarma B., Allu, Srikanth, & Turner, John A. Crashworthiness Models for Automotive Batteries. United States. doi:10.2172/1435250.
Kalnaus, Sergiy, Wang, Hsin, Simunovic, Srdjan, Kumar, Abhishek, Gorti, Sarma B., Allu, Srikanth, and Turner, John A. Mon . "Crashworthiness Models for Automotive Batteries". United States. doi:10.2172/1435250. https://www.osti.gov/servlets/purl/1435250.
@article{osti_1435250,
title = {Crashworthiness Models for Automotive Batteries},
author = {Kalnaus, Sergiy and Wang, Hsin and Simunovic, Srdjan and Kumar, Abhishek and Gorti, Sarma B. and Allu, Srikanth and Turner, John A.},
abstractNote = {Safety is a key element of any device designed to store energy, particularly of electrochemical batteries, which convert energy of chemical reactions to electrical energy. Safety considerations are especially important when applied to large automotive batteries designed for propulsion of electric vehicles (EV). The high amount of energy stored in EV battery packs translates to higher probability of fire in case of severe deformation of battery compartment due to automotive crash or impact caused by road debris. While such demand for safety has resulted in heavier protection of battery enclosure, the mechanisms leading to internal short circuit due to deformation of the battery are not well understood even on the level of a single electrochemical cell. Moreover, not all internal shorts result in thermal runaway, and thus a criterion for catastrophic failure needs to be developed. This report summarizes the effort to pinpoint the critical deformation necessary to trigger a short via experimental study on large format automotive Li-ion cells subjected to large deformations as those occurring in deformation of battery module or pack. Mechanical properties of cell components were determined via experimental testing and served as input for constitutive models of Finite Element (FE) analysis. It has been rationalized that long-range stress fields occurring in spherical indentation of battery modules would trigger different deformation and failure scenarios compared to indentation of a single cell supported by a rigid flat surface. In order to investigate large deformations characteristic of battery module, a custom experimental set up has been built where the pouch cell was deformed against a compliant backing, which was represented by a ballistic clay. Experiments were also conducted on deformation of stacks of 10 pouch cells, - configuration representing half-module in Ford Focus EV battery pack without cooling plates and structural components. Comparison of the results shows promise for the compliant backing setup for safety evaluation of battery cells under more realistic conditions compared to indentation of single cell against undeformable backing where compression and electrode particle penetration through separator could be the major mechanism for short circuit.},
doi = {10.2172/1435250},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2018},
month = {Mon Jan 01 00:00:00 EST 2018}
}

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