A flexible lithium-ion battery built to operate under extreme conditions—including cutting, submersion, and simulated ballistic impact—can now add incombustible to its résumé, researchers say.
Current Li-ion batteries are susceptible to catastrophic fire and explosion incidents—most of which arrive without any discernible warning—because they are built with flammable and combustible materials.
Airlines banned the Samsung Galaxy Note7 phones as a result of this danger, and the Navy prohibited e-cigarettes on ships and submarines as a direct response to the need to reduce the devices’ flammability.
With these batteries emerging as the energy storage vehicle of choice for portable electronics, electric vehicles, and grid storage, these safety advancements mark a significant step forward in transforming the way Li-ion batteries are manufactured and how consumers use them in electronic devices.
In research published in the journal Chemical Communications, researchers detail their latest discovery: a new class of “water-in-salt” and “water-in-bisalt” electrolytes—referred to as WiS and WiBS, respectively—that, when incorporated in a polymer matrix, reduces water activity and elevates the battery’s energy capabilities and life cycle while ridding it of the flammable, toxic, and highly reactive solvents present in current Li-ion batteries.
It’s a safe, powerful alternative, the researchers say.
“Li-ion batteries are already a constant presence in our daily lives, from our phones to our cars, and continuing to improve their safety is paramount to further advancing energy storage technology,” says Konstantinos Gerasopoulos, senior research scientist and principal investigator of Johns Hopkins University’s Applied Physics Laboratory.
“Li-ion battery form factors have not changed much since their commercialization in the early 1990s; we still use the same cylindrical or prismatic cell types. The liquid electrolyte and required hermetic packaging have a lot to do with that,” Gerasopoulos says.
“Our team’s efforts have generally been focused on replacing the flammable liquid with a polymer that improves safety and form factor. We are excited about where we are today. Our recent paper shows improved usability and performance of water-based flexible polymer Li-ion batteries that can be built and operated in open air.”
Additionally, the new approach further improves the damage tolerance initially demonstrated with the team’s flexible battery in 2017.
“The first generation of flexible batteries were not as dimensionally stable as those we are making today,” Gerasopoulos says.
With this latest benchmark reached, the researchers continue to work on further advancements of the technology.
“Our team is continuously improving the safety and performance of flexible Li-ion batteries,” says Jeff Maranchi, the program area manager for materials science at APL.
“We have already achieved further discoveries building upon this most-recently reported work that we are very excited about. We hope to transition this new research to prototyping within the year.”
Source: Johns Hopkins University
