Often, when a vehicle crash occurs, danger persists beyond the initial impact and resulting deformation. Impact can also trigger secondary accidents, such as fire. This is especially true for electric vehicles and those using lithium ion batteries -- a particular concern due to the growth of this market.
Making lithium ion batteries safer by seeking to lower the instances of secondary accidents due to fire is the primary focus behind new research being conducted by Elham Sahraei, Temple University Assistant Professor of Mechanical Engineering.
"We are working on designs for small urban electric vehicles, trying to come up with the best protective designs for the battery packs in these vehicles in case they get into a crash," Dr. Sahraei said.
Partnering with Institut Teknologi Bandung in Indonesia, Dr. Sahraei is building on research from her previous position as a Research Scientist with the Impact and Crashworthiness Lab of the Massachusetts Institute of Technology. There, she also served as co-director of a research consortium supported by major automotive and battery manufacturers such as Mercedes Benz North America R&D, Jaguar Land Rover, LG Chem and Boston Power. "Three primary areas inform this research: structural mechanics, solid mechanics and advanced materials," Dr. Sahraei said, adding that the two-year project is currently underway.
Recent news reports have shared harrowing stories of first responders managing crash scenes where batteries catch fire following temperature spikes, a phenomenon known as "thermal runaway."
"We still use battery cells, but now are focusing on putting those cells together to make a full battery pack, integrating it into the vehicle and seeing how it can impact vehicle safety," she added. By testing batteries in differing deformation configurations, her team can find material properties to inform element models reflecting what would happen in a real-life crash situation. The models will give manufacturers clearer direction on how to create safer lithium ion batteries for electric vehicle application, and also protect them: something that has been of increasing concern of late.
"Before these batteries were in cars, they were in things that weren't being impacted by crashes," Dr. Sahraei noted.
Though 174,000 vehicle fires were reported in the United States in 2015 (the most recent available data) nearly all were involving gas-powered and not electric vehicles. Still, the need for more information is growing with each new crash involving these types of batteries.
"It generates new areas of research like this," Dr. Sahraei said. "It's important to understand: what point causes failure so we can best protect against these possibilities?"