Lithium ion batteries often grow needle-like structures between electrodes that can short out the batteries and sometimes cause fires. Now, an international team of researchers has found a way to grow and observe these structures to understand ways to stop or prevent their appearance.
“It is difficult to detect the nucleation of such a whisker and observe its growth because it is tiny,” said Sulin Zhang, professor of mechanical engineering, Penn State. “The extremely high reactivity of lithium also makes it very difficult to experimentally examine its existence and measure its properties.”
Lithium whiskers and dendrites are needle-like structures only a few hundred nanometers in thickness that can grow from the lithium electrode through either liquid or solid electrolytes toward the positive electrode, shorting out the battery and sometimes causing fire.
The collaborative team from China, Georgia Tech, and Penn State successfully grew lithium whiskers inside an environmental transmission electron microscope (ETEM) using a carbon dioxide atmosphere. The reaction of carbon dioxide with lithium forms an oxide layer that helps stabilize the whiskers.
They report their results in Nature Nanotechnology (“Lithium whisker growth and stress generation in an in situ atomic force microscope–environmental transmission electron microscope set-up”).

Image Credit:  Penn State/Zhang Lab


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