Every so often, you’ll hear news of a Tesla that exploded into a ball of fire or a Samsung phone that went nuclear in the pocket of someone’s jeans. Stories like these can make anyone nervous about the lithium-ion batteries powering their electric vehicles, tablets and smartwatches, which have become an omnipresent part of everyday life. You’re likely reading these words on a lithium-powered device right now.
Lithium-ion batteries are not only safe but also necessary for helping the world transition away from fossil fuels. Still, this technology is relatively new, and there’s work to be done to ensure that these energy storage systems are as safe as possible.
Today we’ll be talking about the safety of lithium-ion batteries. We’ll also be looking at the work of Ofodike Ezekoye, Ph.D., director of the 100% online Master of Science in Mechanical Engineering program and an expert in combustion and heat transfer. If you want to learn more about battery fires, he’s your guy.
Are Lithium-Ion Batteries Safe?
Lithium-ion batteries are safe under normal circumstances. Although rare, fires can occur when there is external damage or an internal fault. Long-lasting with a high energy density, lithium-ion batteries are replacing lead acid batteries in everything from appliances to energy storage. As lithium-ion batteries become more common, however, so too will battery fires.
Fires are hardly a uniquely modern concern, so what exceptional risk does a compromised lithium-ion battery pose? The problem is thermal runaway: a chain reaction that starts when excessive heat triggers the release of more and more heat — like falling dominoes — until the battery ignites and, in some cases, explodes.
Consider the battery pack powering an electric vehicle. Battery packs are made up of battery modules, which are made up of lithium-ion battery cells. Thermal runaway starts when a single cell short circuits and heats up until it bursts with a pop as loud as a gunshot. Surrounding cells undergo the same process, releasing electrolytes and other flammable gases that can, in rare cases, explode.
Electric Vehicle Fires
A lithium-ion battery fire is notoriously difficult to extinguish. Dousing a fire in water may only work on small batteries. Recently, firefighters in Massachusetts needed 20,000 gallons of water to extinguish a Tesla that caught fire after crashing into a guardrail. Worse still, electric vehicle fires release toxic gases and pose an inhalation risk to first responders, which is why many fire departments prefer to let an electric vehicle fire burn itself out.
Worried about spontaneously combusting electric vehicles on your morning commute? We wouldn’t sweat it. Electric vehicles are less likely to catch fire than gas-powered or hybrid vehicles. A car — or anything, for that matter — can catch fire regardless of its power source. We say this to put the fear of battery fires into perspective and to highlight the importance of fire research.
Why Do Lithium-Ion Batteries Fail?
Speaking on an episode of the Fire Science Show published on March 31, 2022, Ezekoye spoke of his experience with battery manufacturing as part of the UT Battery Research Group:
“What’s interesting is that my university, University of Texas, has a long history of sort of excellence in battery materials. … We have a Nobel Laureate. We have distinguished researchers who are working on the battery materials issues … We decided that we were going to embark on an exercise to develop a [battery fabrication and testing facility].”
Ezekoye realized the challenges of battery manufacturing early on. Even with quality control, defects can slip past cell testing and lead to failures. Mechanical damage can occur during a car crash, puncturing the separator between the anode and cathode, for instance. Then there are environmental failures. High temperatures can degrade the separator within a cell or cause reactions that lead to the cascading failure that is thermal runaway.
The Safety of Lithium-Ion Batteries and the Future of Transportation
“Fires have happened forever … Whether we go to space, whether we’re on the sea, fire follows us,” said Ezekoye on that same episode of the Fire Science Show. Lithium-ion batteries will become safer with time. Still, there’s always the chance they’ll be around a fire, if not the cause. The fire risk posed by these energy storage systems is a hurdle we must overcome to facilitate the energy transition.
“The only way that we can solve some of the really unsafe things — climate change, global warming — is to use renewable energy and to use energy storage,” said Ezekoye. The use of fossil fuels, particularly in transportation, has had a severe impact on our planet, and lithium-ion batteries hold the key to green transportation, climate action and a safer future, if only we can set aside our fear of battery technology.
UT Austin Engineers Leads the Way
Looking for more on fire safety? Ezekoye is a regular of the John B. Goodenough Energy Storage Lecture Series, his previous lecture being on the safety of lithium-ion batteries. Led by Ezekoye, the UT Fire Research Group develops strategies to minimize the negative impacts of battery thermal failures. You can read some of their findings on their Battery Fires page.
UT Austin is also home to a 100% online MS in Mechanical Engineering program. Students explore a wide range of engineering topics, including applied thermodynamics. Apply now if you’re interested in learning how mechanical engineering can solve problems and change the world.