A New Soft, Flexible Electrolyte Could Make Solid-State Batteries Better — And Cheaper
New electrolyte is hard enough to prevent dendrites from forming as the battery ages but soft enough to prevent capacity loss.
A research project led by Empa, the Swiss Federal Laboratories for Materials Science and Technology, could prove a breakthrough for solid-state batteries — by replacing existing rigid electrolytic layers with a flexible version instead.
"Today's batteries for medical implants, such as pacemakers, are usually hard and uncomfortable for patients," says project lead Dorina Opris of one of the problems the team is looking to solve. “Our polymer can serve not only as an electrolyte, but also as a binder material for the cathode. Empa researcher Can Zimmerli explains how the technology has broader potential, too: "The flexible polymer can be combined with different cathode active materials, enabling batteries for various applications," he says.
The majority of batteries on the market today are based on a liquid electrolyte, which can cause problems if punctured or exposed to high temperatures — with lithium batteries swelling as they age, owing to the growth of tree-like lithium dendrites in the electrolytic, and potentially igniting if ignored for too long. Solid-state batteries avoid this problem and could theoretically safely deliver higher energy storage densities, but going from a liquid to a rigid solid electrolyte brings its own problems.
The Empa team's solution is something in-between: a flexible, stretchable electrolyte offering high elasticity — solid enough that dendritic growth is prevented, but soft enough that it can fill the gaps left as lithium ions move away from the anode. As a bonus the batteries themselves would become more flexible too, making them better-suited for wearable and implantable use-cases.
"The material can be processed into thin films of a few micrometers in thickness, and it is scalable," Opris claims, with the team working on further improvements while simultaneously seeking a partner to bring the technology to mass production. "If produced on an industrial scale, it is also cheaper than conventional solid polymer electrolytes."
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