Smartphone batteries that decay after too many recharges? Not for long.
Scientists at the University of California Irvine have stumbled upon a technology that could yield batteries that can be recharged hundreds of thousands of times – without any loss to capacity. Their serendipitous discovery, published this week in ACS Energy Letters, came as they investigated how to make nanowire technology less fragile.
“We were not attempting to extend the cycle life of these electrodes – we just were trying to prepare a solid state version of them by substituting a gel electrolyte for the liquid electrolyte,” said paper co-author Reginald Penner, reported the Huffington Post.
Scientists have been eyeing nanowire technology's potential for battery improvements for a while. The wires are extremely thin – thinner than a strand of human hair – and great for holding charges.
“However, the Achilles heel of such nanowires for energy storage is cycle stability,” explained the researchers in their paper. Despite all the pros, fragile nanowires often grow brittle after repeated exposure to the recharge process in batteries.
And when it comes to current battery technology, poor longevity is already a major issue. A new smartphone can hold a charge all day with juice to spare – but after 200 recharges, it might need to be recharged before going out for the evening, and after 2000, it’s best not to stray too far from an outlet.
The typical iPhone lithium-ion battery decays after about 300-400 recharge cycles, after which it can carry around 80 percent of a full charge, reports the New York Times.
In an attempt to make nanowires less fragile, the lead scientist behind the study, UCI doctoral candidate Mya Le Thai, coated a gold nanowire in a shell and surrounded it with a thin layer of a Plexiglas-like gel, according to the press release.
The researchers cycled charges through the new composite and were dazzled by the results.
“We found out we can pass energy through these nanowires hundreds of thousands of times,” Ms. Le Thai said in a video explaining the experiment.
“That was crazy,” Dr. Penner said in the press release, “because these things typically die in dramatic fashion after 5,000 or 6,000 or 7,000 cycles at most.”
Why does it work? The details remain a little unclear, but the gel helps prevent the nanowire from corroding as it receives a charge, say the researchers.
“The coated electrode holds its shape much better, making it a more reliable option,” Thai said.
For now, lithium-ion batteries that decay after hundreds of recharge cycles will remain the only commercially viable option. The UCI research team was testing nanowire, not producing a nanowire battery ready to be shipped to consumers. But the team remains optimistic about their discovery's prospects.
“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,” Thai said.