Session: Research Posters

Paper Number: 172794

A Review of Safety Standards for Propulsion Batteries in Battery Electric Vehicles 

With the rise of battery electric vehicles (BEVs) on the road in recent years, the differences in their crash behavior compared to internal combustion engine vehicles (ICEVs) have become apparent. In addition to having different crash dynamics due to having greater mass and a lower center of gravity, BEVs also pose unique hazards in the event of an accident. BEVs are usually powered by lithium ion (Li-ion) propulsion batteries, and any damage to the battery can trigger thermal runaway. This can lead to rapid, violent and self-sustained combustion. In addition, damage may leave an unknown amount of energy in the battery with no way to discharge it, a condition known as stranded energy. Thermal runaway and stranded energy pose significant risks to the occupants and those involved in responding to the accident, given the difficulty in putting out the battery fire and the possibility of reignition. Despite these safety concerns, there are very few regulations and standards regarding propulsion battery safety in an accident. This lack of formal guidance may lead to unsafe designs and overlooked failure modes when relying solely on safety standards developed for ICEVs. The purpose of this study was to compare different testing procedures for Li-ion batteries and vehicles to find potential gaps. A literature search was conducted, and two sets of vehicle crash tests and six sets of Li-ion battery tests were reviewed. These testing procedures were then analyzed and compared to find areas of overlap. From this work, some gaps were made apparent. The vehicle test procedures are designed to be reflective of common real-world accident scenarios and are important for understanding how the vehicle will respond to those situations. These tests usually focus occupant safety and result in a safety rating for the vehicle. However, the criteria used to create these ratings seldom reference the propulsion battery outside of electrical shock or electrolyte leakage; ratings can be downgraded for catastrophic failure, such as a fire, but the battery is usually not monitored directly. Conversely, many of the testing standards specifically designed for Li-ion batteries aim to characterize specific battery failure modes. This provides useful information, but because these tests isolate one failure mode at a time and are usually conducted on a single cell or module, they are usually not reflective of what a full propulsion battery might experience in an accident. Therefore, given the results of this preliminary research, testing guidelines and procedures specifically for propulsion batteries are being developed. A multiphysics simulation model of a BEV battery pack is also being created to assist in developing these procedures to get a holistic picture of the propulsion battery’s behavior in an accident.

Presenting Author: Kelly Richardson George Mason University

Presenting Author Biography: Kelly Richardson is an Engineering Physics PhD student at George Mason University, currently working in the Center for Collision Safety and Analysis on electric vehicle battery safety. She also holds a master’s degree in Applied and Engineering Physics from George Mason University and a bachelor’s degree in Engineering Science and Mechanics from Virginia Tech.

Authors:

Kelly Richardson George Mason University
Leyu Wang George Mason University
Chung-Kyu Park George Mason University
Cing-Dao Kan George Mason University