A nanowire-based battery material that can be recharged hundreds of thousands of times has been developed by researchers at University of California, Irvine, edging us closer to a battery that would never require replacement. The breakthrough invention could lead to commercial batteries with vastly lengthened lifespans for smartphones, computers, cars and spacecraft.
The findings were published in the American Chemical Society’s Energy Letters.
Scientists have long attempted to use nanowires in batteries. Thousands of times thinner than a human hair, they’re highly conductive and feature a large surface area for the storage and transfer of electrons.
However, these filaments are highly 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.
Manganese Dioxide Shell
The researchers 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 is reliable and resistant to failure.
Hard work combined with serendipity paid off in this case, according to senior author Reginald Penner.
Study leader, UCI doctoral candidate Mya Le Thai, was playing around, said Penner, and:
“She 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. because these things typically die in dramatic fashion after 5,000 or 6,000 or 7,000 cycles at most.”
Thai cycled the testing electrode up to 200,000 times over three months without detecting any loss of capacity or power and without fracturing any nanowires. The researchers believe the gel plasticizes the metal oxide in the battery and gives it flexibility, preventing cracking.
Original research: 100k Cycles and Beyond: Extraordinary Cycle Stability for MnO2 Nanowires Imparted by a Gel Electrolyte