Researcher Accidentally Develops Way to Make Batteries Last 400 Times Longer

Many researchers are working on the problem of how to give lithium-ion batteries a longer lifetime. But recently some -- specifically a student researcher at the University of California Irvine -- accidentally stumbled upon what might be a way to solve the problem.

Mya Le Thai, a student of Professor Reginald Penner in the university’s Department of Chemistry, was attempting to prepare a solid-state version of an all-nanowire capacitor the team had developed by replacing the device’s usual liquid electrolyte with a viscous gel, Penner told Design News. What she didn’t know was that the experiment would positively influence cycle stability in the devices.

University of California Irvine chemist Reginald Penner and doctoral candidate Mya Le Thai (shown) have developed a nanowire-based technology that allows lithium-ion batteries to be recharged hundreds of thousands of times, or 400 times more than typical batteries used today.
(Source: Steve Zylius/University of California Irvine)

“When she started to cycle these capacitors, there was no evidence of capacity loss after 20,000 cycles, or, a few days later, 40,000 cycles, or, a week later, 80,000 cycles, etc.,” Penner said. “After 100,000 cycles with close to zero capacity fade, she just asked me whether she could turn off the experiment and start a new one because we only have a few potentiostats in the lab that can be used for this work. One capacitor was run for 200,000 cycles without fading at all. This was completely mind blowing for us.”

Researchers have wanted to use nanowires in batteries for some time because they are thousands of times thinner than a human hair, are highly conductive, and feature a large surface area for the storage and transfer of electrons. However, on the down side, they are fragile and don’t hold up well to repeated discharging and recharging or cycling. In a typical lithium-ion battery, they expand and grow brittle, which leads to cracking.

UCI researchers have solved this problem by coating a gold nanowire in a manganese dioxide shell to make it more durable. That combined with the electrolyte made of a Plexiglass-like gel provided a combination that not only was reliable, but also longer lasting than any other capacitor developed before, Penner said.

Usually, when this capacitor is charged and discharged across 1.2V, it withstands 5,000 cycles before beginning to lose capacity, or the amount of charge that is stored, he explained. Substituting a gel electrolyte for the liquid electrolyte increased the cycle lifetime to 100,000 cycles, or more.

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While the device developed by researchers was a capacitor, not a battery, the nanowires in the device would be suitable for use as cathodes in a lithium ion battery,” Penner said. “The anode of this battery would need to be composed of another material, such as graphite typically,” he said. In this way, the breakthrough work could lead to commercial batteries with greatly lengthened lifespans for computers, smartphones, appliances, cars, and spacecraft.

But don’t get too excited about the possibility of batteries that last 400 times longer than your average iPhone battery quite yet, he warned. “This discovery is a long way from commercialization,” Penner said. Still, the research provides an “expedient, easily implemented method for stabilizing manganese oxide nanowires against degradation and failure in one type of energy storage device,” and with optimization, it could one day be applied to commercial batteries, he said.

The team will continue its research to experiment with a number of aspects of the capacitor to make improvements, Penner said. “We want to see whether higher voltages can be accessed in the gel electrolyte, whether other types of nanowires (besides manganese oxide) can be stabilized by these gels, and whether other types of gels might be better for this purpose than the one we've tested,” he said.

Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 15 years. She has lived and worked as a professional journalist in Phoenix, San Francisco, and New York City. In her free time she enjoys surfing, traveling, music, yoga, and cooking. She currently resides in a village on the southwest coast of Portugal.