| Abstract: | While the popularity of lithium-ion batteries (LIBs) has increased significantly in recent years, safety concerns due to the high thermal instability of LIBs limit their use in applications with zero tolerance for failure. A safety issue of particular interest is a scenario called thermal runaway in which several exothermic side-reactions occur at elevated temperature ranges and release heat, which can then trigger the next reaction. This matter worsens when multiple cells are installed in close proximity to each other as the released heat from an abused cell can activate the chain of reactions in a neighboring cell, causing an entire module to heat rapidly and vent or ignite. This body of work aims to study LIB thermal behavior using both modeling and experiments to determine design practices that improve the safety of LIB modules. Based on the results of single cell abuse testing, a numerical model of the side-reactions that occur during thermal runaway was developed. The results showed that cell form factor and ambient conditions influence abuse behavior significantly. These abuse tests were extended to multi-cell modules to determine the effect of cell spacing, electrical configuration, and protection materials on the propagation of thermal runaway from an abused cell to a surrounding one. Lastly, an electrochemically coupled thermal model of battery thermal management systems of various configurations was created. An optimum thermal management design was found that utilized both active and passive methods of cooling to keep cell temperatures and thermal gradients within safe limits. The work described herein is expected to provide insight into safe battery design practices. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/155326 |
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