While scientists have long sought to use nanowires in batteries – they are highly conductive and feature a large surface area – they are fragile and don't withstand repeated discharging and recharging.
The UCI researchers say they have solved 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. The combination, they contend, is reliable and resistant to failure.
Researcher Mya Le Thai cycled the test electrode up to 200,000 times over three months without detecting any loss of capacity or power and without fracturing any nanowires.
Reginald Penner, pictured, chair of UCI’s chemistry department, noted: “Mya was playing around and coated this whole thing with a very thin gel layer and started to cycle it. 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 7000 cycles at most.”
The researchers think the gel plasticises the metal oxide in the battery and gives it flexibility, preventing cracking.
“The coated electrode holds its shape much better, making it a more reliable option,” Thai said. “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.”