They’re 20,000 times smaller than the thickness of a human hair, but nanomaterials play a big role in the research of Chemistry Professor Michael Wagner
, whose work focuses on creating microscopic tubes, rods, particles and spheres used in everything from batteries to thermoelectric refrigerators.
Wagner’s work has resulted in a breakthrough in rapidly charging batteries. A typical lithium ion battery with graphite electrodes can take two hours to charge. But Wagner’s batteries can be recharged much more quickly: A 20 percent charge takes just seven seconds since his batteries contain hollow carbon nanosphere electrodes. Because of the nanomaterials used in the chemistry, the distances lithium ions have to travel into the electrodes is reduced, allowing a faster charge.
The research has great potential for automobiles. “We’re hoping to develop batteries that can be charged in a reasonable amount of time instead of overnight, much like you refill your car today, except you’re refilling it with electricity,” Wagner said.
The new technology is possible because of the unique properties of nanomaterials. Even common elements behave very differently when reduced to nanoscale, and the “quantum effects” phenomenon takes over. “The physics can be quite different when materials are nanoscale,” Wagner said. He noted that at such small sizes, the way a material conducts heat and electricity can change, as can the melting point, overall strength and other physical properties.
Wagner’s testing and research has enabled him to tailor nanomaterials for many applications. For example, he and his research group of graduate students are testing nanomaterials in thermoelectric devices, which create voltage through differences in temperatures. The uses for thermoelectrics range from portable refrigerators to deep space probes that need a long-term power source. Wagner is also studying the use of nanomaterials for magnetic refrigerators, devices that don’t need an electric compressor or the ozone-depleting Freon gas. Another project explores the more efficient phosphors for next-generation display technology that may someday replace current big screen TVs and computer monitors.
As a materials chemist, Wagner works with substances with “interesting” properties that can be used for a variety of applications. “Whether they are commercial is not the primary goal. Advancing the science is much more important.”