Washington: An Indian-origin scientist-led team in the US has packaged lithium ion batteries into a single nanowire, which they claim could soon be a rechargeable power source for new generations of nanoelectronics.Prof Pulickel Ajayan and colleagues at Rice University claim their creation is as small as such devices can possibly get, in their research published in American Chemical Society journal `Nano Letters`.
In their research, the scientists tested two versions of their battery.
The first is a sandwich with nickel or tin anode, polyethylene oxide electrolyte and polyaniline cathode layers; it was built as proof that lithium ions would move efficiently through anode to electrolyte and then to supercapacitor-like cathode that gives the device ability to charge and discharge.
The second packs the same capabilities into a single nanowire. The researchers built centimetre-scale arrays containing thousands of nanowire devices, each 150 nanometers wide. A nanometer is a billionth of a meter, thousands of times smaller than a human hair.
"The idea here is to fabricate nanowire energy storage devices with ultrathin separation between the electrodes," said Arava Leela Mohana Reddy, a research scientist at Rice and the study`s co-author.
"This affects the electrochemical behavior of the device. Our devices could be a very useful tool to probe nanoscale phenomenon," she added.
The team`s experimental batteries are about 50 microns tall – about the diameter of a human hair and invisible when viewed edge-on, Reddy said.
The nanowire devices show good capacity; the researchers are fine tuning the materials to increase their ability to repeatedly charge and discharge, which now drops off after a about 20 cycles.
"There`s a lot to be done to optimise the devices in terms of performance. Optimisation of the polymer separator and its thickness and an exploration of different electrode systems could lead to improvements," the researchers said.
First Published: Sunday, July 31, 2011, 16:08