Researchers have designed and built a new lithium ion battery with a built-in flame-retardant that’s released when the battery is overheated. Since their introduction in the 1970s, lithium-ion batteries have emerged as among the most successful technologies for portable, lightweight storage of electrical energy.
As a result, these batteries are under active development worldwide for multiple applications, including powering electric vehicles, autonomous aircraft and advanced robotics.
Unfortunately, safety problems associated with their use of highly flammable liquid electrolytes continue to plague widespread commercial deployment. In Science Advances, Kai Liu and colleagues propose a lithium battery in which the separator, which keeps the negative and positive electrodes apart, hosts the powerful frame retardant, tri-phenyl phosphate (TPP), encapsulated in a woven polymer “protective shell”.
During normal battery operation, the flame retardant is isolated from other cell components and the battery functions normally. If the temperature of the separator rises above 150 °C, the retardant is rapidly released, quenching the flame.
The researchers measured the extinguishing time of TPP, finding that the retardant, once released, is able to completely extinguish an electrolyte flame in 0.4 seconds.