Putting out electric vehicle fires with saltwater

Researchers at the University of Central Florida (UCF) have developed technology that could prevent electric vehicle fires like those caused by saltwater flooding from Hurricane Ian. The technology is an aqueous battery that replaces the volatile and highly flammable organic solvents found in conventional lithium-ion batteries, including those that power electric vehicles, with saltwater. This creates a battery that is safer and faster-charging than lithium-ion batteries, but which is just as powerful and won’t short-circuit during flooding. The researchers report their work in a paper in Nature Communications. “During Hurricane Ian, a lot of electric cars caught fire after they were soaked in floodwater,” says Yang Yang, an associate professor in UCF’s NanoScience Technology Center, who led the research. “That is because the saltwater corrodes the battery and causes a short circuit, which ignites the flammable solvents and other components. Our battery uses saltwater as an electrolyte, eliminating the highly volatile solvents.” By using saltwater as the battery’s liquid electrolyte, the UCF researchers were able to utilize the naturally occurring metal ions found in saltwater, such as sodium, potassium, calcium and magnesium, to create a dual-cation battery that stores more energy. This implementation allowed them to overcome the sluggishness of previous single-cation aqueous batteries. The battery’s novel nano-engineering also helped it overcome the limitations of previous aqueous batteries. These include slow charging times, low energy output, instability and corrosion, as well as the growth of harmful metallic structures called dendrites on the negative electrode. The researchers engineered a zinc-copper anode with a thin zinc oxide protective layer on top. This novel nano-engineered surface, which looks like a birds-eye-view of a forest, allowed the researchers to precisely control electrochemical reactions, thereby increasing the battery’s stability and quick-charging ability. As a result, the battery is able to reach full charge in just three minutes, compared to the hours it takes lithium-ion batteries. Furthermore, the zinc oxide layer prevents dendritic growth of zinc, which was confirmed using optical microscopy. “These batteries using the novel materials developed in my lab will remain safe even if they are used improperly or are flooded in saltwater,” Yang says. “Our work can help improve electric vehicle technology and continue to advance it as reliable and safe form of travel.” The issue of electric vehicle fires after saltwater flooding surfaced during Hurricane Sandy in 2012 and Hurricane Isaias in 2020. As a result, the US Fire Administration and the National Highway Traffic Safety Administration have issued special guidance for responding to electric vehicle fires caused by saltwater flooding. According to the US Fire Administration, at least 12 electric vehicle fires were reported in Collier and Lee counties in Florida after Hurricane Ian, where many cars were submerged at least partially in saltwater. This story is adapted from material from the University of Central Florida, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.