World's Smallest Battery
A desire to understand batteries "from the bottom up" motivated Wang, fellow PNNL researcher Wu Xu, DOE Sandia National Laboratories nanotechnology scientist Jianyu Huang, and researchers from the University of Pittsburgh and University of Pennsylvania to create the world's smallest lithium ion battery, a feat they reported in the Dec. 10 issue of the journal Science.
One seven-thousandth the thickness of a human hair, the battery's 100-nanometer-wide anode, through which electric charge flows in, is a single nanowire made of tin oxide, Xu explained. From the single-wire anode, the nanobattery's electric current flows through a liquid electrolyte to a lithium-cobalt oxide cathode.
It's a design that mimics the ubiquitous consumer electronics battery, albeit on a far smaller scale.
In a rechargeable lithium ion battery (LIB), positively charged lithium ions move from a negative electrode (the anode) to a positive electrode (the cathode) during electric discharge, and back again during recharge.
Lithium ions make great battery chargers because they strongly gravitate toward electrons, initially clustering around the cathode. As charging pumps free electrons into the anode, lithium ions make haste across an electrolyte fluid, flowing from the cathode to the anode.
Playing tunes on an iPod or downloading email on a notebook depletes the newly charged battery, causing electrons to flee the anode while leaving lithium ions behind. In time, those ions return to the cathode, back across the electrolyte fluid.
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