Experimental Investigation of Polymer Composite-Based Protective Structures for Mitigating Crash-Induced Mechanical Abuse in Lithium-Ion Batteries

Abstract

The objective of this paper is to determine the effectiveness of using polymer composite protective structures to protect against the mechanical abuses associated with crash impacts that affect lithium ion batteries in terms of their structural integrity and their overall safety. In addition to their use in electric vehicles, lithium ion batteries are also being increasingly used in renewable energy based energy storage systems because they have high energy densities, long lifetimes, and superior performance characteristics. As a result of their widespread use, it has become clear that there are major safety concerns with respect to their susceptibility to mechanical failure due to crash induce mechanical abuse. Such mechanical failures can lead to internal shorts; structural deformations which can result in thermal instabilities; and reduced electrical performance. Therefore, this study investigated the use of advanced polymer composite materials to provide protection from mechanical failure when subjected to crash impacts. To achieve this goal, an extensive test program was developed to evaluate the effect of various types of polymer composite materials on the behavior of 18650 lithium ion cells during drop and impact testing. Mechanical responses evaluated included impact energy, stress, strain, and displacement. Electrical response evaluations included changes in voltage, current, and state of charge, internal resistance and capacity retention. These evaluations examined whether or not polymer composites could be effectively used as lightweight absorbing materials to reduce the effects of crash induced mechanical loading. Additionally, these studies established a correlation between crashes induced mechanical loading and electrochemical degradation.