With high conductivity and a large surface area, nanowires have become quite the candidate for an advanced battery material. But at thousands of times thinner than a human hair, their delicate nature often causes them to fracture throughout the battery cycle. By designing a nanowire-based electrode with a special protective coating, researchers now claim to have overcome this limitation, which could lead to batteries able to withstand hundreds of thousands of recharge cycles.
Recently, scientists have made some promising strides when it comes to enhancing the properties of nanowires for the purpose of building better batteries. In 2012, Stanford researchers tweaked the recipe a little to give nanowires a greater surface area, as did researchers at MIT in 2013. Also in 2013, scientists had some success using silicon nanowires to build a lithium-ion battery that held three times the energy of a conventional version, thought it could only withstand around 200 recharge cycles.
With their new nanowire-based electrode, researchers at University of California, Irvine aren't yet claiming increased battery capacity, but a material with a much greater lifespan. Early testing of the component has shown that it can withstand hundreds of thousands of cycles, compared to current versions which they say usually die after around 7,000 cycles at most.
The researchers began with a gold nanowire, and then coated it in a manganese dioxide shell. It was then encased in an electrolyte made from a gel similar to Plexiglass. They put the electrode to the test by cycling it up to 200,000 times over a period of three months, detecting no loss of capacity, power, or fracturing in any of the nanowires.
The researchers believe that the gel plasticizes the metal oxide within the battery, affording it just the right amount of give to prevent it cracking throughout the charging cycles.
"The coated electrode holds its shape much better, making it a more reliable option," says UCI doctoral candidate, Mya Le Thai. "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."
The research was published in the journal Energy Letters.
Source: University of California, Irvine