In recent years, there have been a number of well-publicized cases of batteries in laptops and other electronics systems overheating and catching fire. To combat this, researchers at Johns Hopkins University’s Applied Physics Laboratory have developed a flexible lithium-ion battery that is built to operate under extreme conditions—including cutting, submersion, simulated ballistic impact, and incombustibility.
In research published recently in the journal Chemical Communications, the research team, led by Konstantinos Gerasopoulos of APL's Research and Exploratory Development Department, gave details on a new class of "water-in-salt" and "water-in-bisalt" electrolytes—referred to as WiS and WiBS, respectively. When incorporated in a polymer matrix, these electrolytes reduce water activity and elevate the battery's energy capabilities and life cycle, while at the same time ridding it of the flammable, toxic, and highly reactive solvents present in current Li-ion batteries.
"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," said Gerasopoulos, senior research scientist and principal investigator at APL, in a statement. "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.
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"Our team's efforts have generally been focused on replacing the flammable liquid with a polymer that improves safety and form factor,” Gerasopoulos added. “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."
The researchers noted that the damage tolerance initially demonstrated with the team's flexible battery in 2017 is further improved in this new approach to creating Li-ion batteries.
"Our team is continuously improving the safety and performance of flexible Li-ion batteries," said 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."