That black dot isn’t a battery, it’s an ultra-thin disc containing thousands of individual nanowire batteries. Rice University scientists claim their miniscule wires are “as small as such devices can possibly get,” because every one comes complete with its own anode, cathode and gel-like electrolyte coating. This contrasts with previous examples we have seen, which bolted nanowires onto a corpulent exterior cathode. Having said that, these new all-in-one nano-batts only last for 20 charge cycles, so personally we’re still betting on gooey Cambridge crude to be a better big thing in electricity. Full PR after the break.
Hybrid energy storage device is as small because it can possibly get
The area at large runs on lithium ion batteries. New research at Rice University shows that tiny worlds may soon do an identical.
The Rice lab of Professor Pulickel Ajayan has packed a whole lithium ion energy storage device right into a single nanowire, as reported this month within the American Chemical Society journal Nano Letters. The researchers believe their creation is as small as such devices can possibly get, and will be valuable as a chargeable power source for brand new generations of nanoelectronics.
Of their paper, researchers described testing two versions in their battery/supercapacitor hybrid. The primary is a sandwich with nickel/tin anode, polyethylene oxide (PEO) electrolyte and polyaniline cathode layers; it was built as proof that lithium ions would move efficiently throughout the anode to the electrolyte after which to the supercapacitor-like cathode, which stores the ions in bulk and offers the device the power to charge and discharge quickly.
The second one packs an analogous capabilities right into a single nanowire. The researchers built centimeter-scale arrays containing thousands of nanowire devices, each about 150 nanometers wide. A nanometer is a billionth of a meter, thousands of times smaller than a human hair.
Ajayan’s team have been inching toward single-nanowire devices for years. The researchers first reported the creation of 3-dimensional nanobatteries last December.
In that project, they encased vertical arrays of nickel-tin nanowires in PMMA, a usual polymer best generally known as Plexiglas, which served as an electrolyte and insulator. They grew the nanowires via electrodeposition in an anodized alumina template atop a copper substrate. They widened the template’s pores with a straightforward chemical etching technique that created an opening between the wires and the alumina, after which drop-coated PMMA to encase the wires in a smooth, consistent sheath. A chemical wash removed the template and left a forest of electrolyte-encased nanowires.
In that battery, the encased nickel-tin was the anode, however the cathode needed to be attached at the outside. The hot process tucks the cathode contained in the nanowires, said Ajayan, a professor of mechanical engineering and materials science. On this feat of nanoengineering, the researchers used PEO because the gel-like electrolyte that stores lithium ions and in addition serves as an electric insulator between nanowires in an array.
After much trial and mistake, they settled on an easily synthesized polymer often called polyaniline (PANI) as their cathode. Drop-coating the widened alumina pores with PEO coats the insides, encases the anodes and leaves tubes on the top into which PANI cathodes may be drop-coated. An aluminum current collector put on top of the array completes the circuit.
“The concept here’s to manufacture nanowire energy storage devices with ultrathin separation between the electrodes,” said Arava Leela Mohana Reddy, a research scientist at Rice and co-author of the paper. “This affects the electrochemical behavior of the device. Our devices is usually a very useful gizmo to probe nanoscale phenomenon.”
The team’s experimental batteries are about 50 microns tall — concerning the diameter of a human hair and almost invisible when viewed edge-on, Reddy said. Theoretically, the nanowire energy storage devices is additionally as long and wide because the templates allow, which makes them scalable.
The nanowire devices show good capacity; the researchers are fine-tuning the materials to extend their ability to continually charge and discharge, which now drops off after a about 20 cycles.
“There is a lot to be done to optimize the devices when it comes to performance,” said the paper’s lead author, Sanketh Gowda, a chemical engineering graduate student at Rice. “Optimization of the polymer separator and its thickness and an exploration of alternative electrode systems could lead on to improvements.”
Rice graduate student Xiaobo Zhan is a co-author of the paper.
The Hartley Family Foundation, Rice University, National Institutes of Health, Army Research Office and Multidisciplinary University Research Initiative supported the research.
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