For the first time, researchers have been able to open a kind of window into the inner workings of a lithium-ion battery. Using a neutron¹ beam, chemists and engineers at The Ohio State University were able to track the flow of lithium atoms into and out of an electrode in real time as a battery charged and discharged.

 

The study, published in the Sept. 1 issue of the journal Angewandte Chemie International Edition, suggests that neutron depth profiling (NDP) could one day help explain why rechargeable batteries lose capacity over time, or sometimes even catch fire.

 

Ohio State researchers are using the technique to test new, high-capacity electrode materials, including ones containing tin, silicon², germanium and aluminum³. These alternative electrodes could be capable of storing nearly three times as much energy as graphite, the material of choice in current lithium-ion batteries. They may also be less prone⁴ to overheating.

 

To Marcello Canova, assistant professor of mechanical and aerospace⁵ engineering at Ohio State, this successful application of NDP represents a huge step forward in studies of how batteries work.

 

Until now, Canova explained, researchers could only measure a lithium-ion battery's output (in voltage and current) and then make computer models of what might be going on inside -- a process that he likened to "trying to study the combustion⁶ processes in a car engine when all you can do is measure the torque and speed at the wheels."

 

"This is the first time that anyone has been able to directly verify how the lithium concentration evolves in space and time within the electrode of a live battery cell containing a typical wet electrolyte," he said. "We believe this will pave the way to an improved understanding of the material and chemical processes that power batteries."

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