I own dozens of devices that are still perfectly functional, except for one small problem: Their batteries are dead. It's a common story. Lithium-ion batteries have improved, but our smartphones and tablets still die after several hundred recharges, or two-years or so of daily use. That may be changing.
University of California, Irvine researchers recently invented nanowire-based battery material that can be recharged not hundreds of times but hundreds of thousands of times. Dare we say it? These batteries might last practically forever.
Scientists have been working on nanowire batteries for some time. Nanowire batteries, with their wires thousands of times thinner than a human hair feature a large surface area for the storage and transfer of electrons. There was only one small, but fatal, flaw, the wires were fragile. They quickly grew brittle and cracked and their effective lifetime was even shorter than conventional Lithium-ion batteries.
The researchers beat this problem by coating a gold nanowire in a manganese dioxide shell and encasing the assembly in an electrolyte made of a Plexiglas-like gel. These encased wires, according to the study leader, UCI doctoral candidate Mya Le Thai, were cycled up to 200,000 times over three months without any loss of capacity or power and without fracturing any nanowires. A 24-hour charge smartphone battery with that kind of lifetime would be good for more than 500 years.
Now that's my kind of battery life!
The discovery came about because of a combination of hard work and good luck. "Mya was playing around, and she coated this whole thing with a very thin gel layer and started to cycle it," said Reginald Penner, chair of UCI's chemistry department, to Phys,org . "She discovered that just by using this gel, she could cycle it hundreds of thousands of times without losing any capacity."
"That was crazy," he added, "because these things typically die in dramatic fashion after 5,000 or 6,000 or 7,000 cycles at most."
The idea of a protective coating making nanowire batteries stronger isn't a new one. Researchers at the U.S. Department of Energy's Argonne National Laboratory have been working on Silicon-based nanowire batteries that could double or even triple the energy stored in conventional batteries. These batteries require a protective coat to even approach today's Lithium-ion battery lifespans, never mind the centuries that might be might possible with Thai's work.
Thai explained that in her work, "The coated electrode holds its shape much better, making it a more reliable option." Therefore, "This research proves that a nanowire-based battery electrode can have a long lifetime and that we can make these kinds of batteries a reality."
It's a long way though from the lab-bench to the marketplace. Still, with our ever increasing hunger for battery-powered devices, we can be certain that if this technology can be commercialized, it will be. I hope to see forever batteries in the marketplace by the early 2020s.