Researchers build nanowire 'hybrid' battery

Researchers at a Houston university have built a nanowire "hybrid" battery that can potentially run a new generation of miniaturized electronic devices. A team at Rice University in Houston managed to pack the rechargeable lithium-ion energy storage device into a nanowire about the diameter of a human hair. "The idea here is to fabricate nanowire energy storage devices with ultrathin separation between the electrodes ... This affects the electrochemical behavior of the device. Our devices could be a very useful tool to probe nanoscale phenomenon," said Arava Leela Mohana Reddy, a Rice research scientist and co-author of the paper. The device is a hybrid between a battery and a supercapacitor. A capacitor is capable of discharging power quickly. But for now, the researchers are still fine-tuning the device to improve its ability to charge and discharge, noting it presently drops off after 20 cycles. Sanketh Gowda, a chemical engineering graduate student at Rice and lead author of the paper, admitted there is much to be done to optimize the device's performance. "Optimization of the polymer separator and its thickness and an exploration of different electrode systems could lead to improvements," Gowda said. Reddy said the team's experimental batteries are about 50 microns tall, almost invisible when viewed edge-on. Theoretically, the nanowire energy storage devices can be as long and wide as the templates allow, making them scalable. In their paper, researchers tested two versions of their battery/supercapacitor hybrid. The first is a sandwich with nickel/tin anode, polyethylene oxide (PEO) electrolyte and polyaniline cathode layers. A second packs the same capabilities into a single nanowire. Only last December, the researchers reported the creation of three-dimensional nanobatteries, encasing vertical arrays of nickel-tin nanowires in Plexiglas. In that battery, the encased nickel-tin was the anode, but the cathode had to be attached on the outside. Mechanical engineering and materials science professor Pulickel Ajayan said the new process tucks the cathode inside the nanowires. The Hartley Family Foundation, Rice University, National Institutes of Health, Army Research Office and Multidisciplinary University Research Initiative supported the research. CNET: medical devices to benefit? A separate article on tech site CNET said the nano battery can be used to power implantable medical devices, chemical and biological sensors, and microscopic wireless networks. They could also enable tiny embedded computers in devices, "which could cause countless everyday objects to have 'smart' added to their names," it added. — TJD, GMA News