Mechanical Integrity of Cylindrical 21700 Lithium-Ion Batteries Based on Electrochemical Status

1 online resource (88 pages) : PDF

2020

University of North Carolina at Charlotte

The sustainability requirement for both the energy and environment has triggered clean energy usage in the automotive industry such that electric vehicles (EVs) powered by lithium-ion batteries (LIBs) have now become the popular choices for current internal combustion automobiles. However, one of the biggest hurdles that discourage customers from purchasing EVs is the safety issues of LIBs. The situation even deteriorates with the recent application of higher energy density LIBs in vehicles for longer ranges. One of the direct causations of the internal short circuit and thermal runaway issues are possible crash accidents. To tackle this problem, in this work, the mechanical behaviors of the widely used 21700 LIB cells and the electrodes are targeted. Systematic characterizations considering strain rate effects, material directions, state of charges (SOCs), and charging cycles are conducted for anodes, cathodes, and the current collectors. Both anodes and cathodes are strongly strain rate dependent. Particularly, SOC has a significant influence over the mechanical behaviors of the anode due to the intercalation induced particle expansion. In the meantime, several finite element models for anodes and cathodes are developed for future full cell modeling. A strong electrochemical effect over mechanical behaviors is observed and discovered. Results provide a basic and comprehensive understanding of the mechanical behaviors of the electrodes used in the 21700 NCM batteries and lay a strong foundation for future multiphysics modeling from the cell level, pack level, and up to the EV level.

masters theses

Mechanical engineering

M.S.

Current Collectors
Electrochemical
Electrode
Lithium Ion Battery
Mechanical Integrity

Mechanical Engineering

Xu, Jun

Uddin, Mesbah
Ghasemi, Amirhossein

Thesis (M.S.)--University of North Carolina at Charlotte, 2020.

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Sonwane_uncc_0694N_12632

http://hdl.handle.net/20.500.13093/etd:2252