Kevlar is a heat-resistant and strong synthetic fiber related to other aramids like Nomex and Technora. Developed by Stephanie Kwolek at DuPont in 1965, the high-strength material was first used commercially in the early 1970s to replace steel in racing tires. These fibers are known for their bullet protection and fire-resistant applications. However, researchers have now used Kevlar fibers to store up to five times the energy of today’s lithium-ion solutions.
A team of researchers at the University of Michigan has taken a step toward realizing kevlar’s real-world potential. The breakthrough hinges on a naturally inspired membrane that overcomes stability issues and offers the battery a “nearly perfect” design, enabling it to last for a thousand-plus cycle. As a lithium-sulfur battery is cycled, tiny particles of lithium and sulfur known as lithium polysulfides flow to the lithium and compromise the device’s capacity. The team addressed this by integrating tiny, bio-inspired channels into its artificial membrane and adding an electrical charge, which repels the particles while allowing the positively charged lithium ions to flow freely.
In a real-world setting with fast-charging technology, the scientists expect the battery would last for around 1,000 cycles, which is considered a 10-year lifespan. Also working in the device’s favor is that sulfur is more abundant and less problematic to source than the cobalt used in lithium-ion batteries. At the same time, the aramid fibers can be harvested from old bulletproof vests making it an overall more environmentally friendly proposition.
Nicholas Kotov, leader of the research team, said, “Several reports are claiming several hundred cycles for lithium-sulfur batteries, but it is achieved at the expense of other parameters – capacity, charging rate, resilience, and safety. Nowadays, the challenge is to make a battery that increases the cycling rate from the former 10 cycles to hundreds of cycles and satisfies multiple other requirements, including cost.”
Such batteries powered by textile fibers could be a game-changer for the upcoming smart textile market. The extended lifespan of these could be used for biomedical signals, and thus, it could significantly alter the quality of life.
