A new study by University of Wisconsin-Madison engineers shows solid-state batteries can offer real safety advantages over lithium-ion batteries but can still catch fire and burn in a worst-case accident scenario.
“Our research shows that the scientific community shouldn’t take for granted that safety isn’t an issue for solid-state batteries,” says Eric Kazyak, an assistant professor of mechanical engineering at UW-Madison who led the study. “As these next-generation batteries start making their way into commercial products, real thought needs to be given to making them as safe as possible.”
There’s significant commercial interest in solid-state batteries because their high energy density could enable electric vehicles with much longer driving ranges.
These batteries are thought to be intrinsically safer than lithium-ion batteries because they use a non-flammable solid electrolyte instead of a flammable, volatile liquid electrolyte. However, there has been little experimental evidence demonstrating the actual safety of solid-state batteries in real-world scenarios.
Now, UW-Madison engineers have completed a comprehensive experimental study of the safety profiles of the various material choices and cell architectures being developed for solid-state batteries. They detailed their findings in a paper published on July 25, 2026, in the Journal of Materials Chemistry A.
For the study, PhD student Jonathan Fakkema, the lead author on the paper, manufactured a range of solid-state batteries made of different configurations of materials. Then, the researchers placed each battery directly inside a propane flame to see what would happen in a worst-case scenario, such as an electric vehicle crash.
“We’re interested in finding out if certain solid-state battery configurations are more likely to create a catastrophic safety incident due to how they catch fire and burn in a worst-case scenario, which could threaten human life and property,” Kazyak says. “Companies are making different material choices in developing their batteries because there are various tradeoffs, and we’re trying to understand what implications those choices have on the future safety profile of these batteries in extreme conditions.”
For their burn tests, the researchers quantified how long each battery burned and how much heat it generated. They also used high-speed imaging technology to observe how quickly a flame propagated across the cell and how gasses and particles were ejected.
Through these tests, the researchers found that a battery configuration with a ceramic solid electrolyte burned significantly slower and generated heat at a lower rate than a lithium-ion battery under the same conditions. “We showed that this type of solid-state battery will still burn, but it’s less likely to quickly result in a catastrophic event because of the slower flame propagation,” Kazyak says. “That’s beneficial for safety because it allows for more time for people get out of a vehicle in a worst-case scenario.”
The researchers used facilities and instrumentation in the UW-Madison Wisconsin Center for Nanoscale Technology, which is partially supported by the Wisconsin Materials Research Science and Engineering Center (NSF DMR-230900) and UW-Madison.
Featured image caption: Assistant Professor Eric Kazyak (right) and PhD student Jonathan Fakkema in Kazyak’s lab. Credit: Joel Hallberg.