Chris Van de Walle

Keeping a battery charged is one of the necessities of life these days, whether it’s in a laptop, cell phone, or automobile. UCSB researchers have discovered a way to lengthen that charge at a molecular level in sodium-ion batteries, an increasingly intriguing power cell.

Lithium is the most commonly used ingredient in small but powerful batteries, but the availability of the element is limited. Scientists are looking at sodium as a more ubiquitous source but have been stymied by the sodium ion’s shorter lifetime in battery form. In particular, sodium manganese dioxide (NaMn02) is being investigated for power storage, and members of UCSB professor Chris Van de Walle’s Computational Materials Group examined the action of hydrogen, introduced unintentionally into the battery, on its longevity.

Van de Walle and his lab’s post-docs Zhen Zhu and Hartwin Peelaers found that hydrogen not only entered the material easily but broke apart the manganese-oxide “backbone” that held the molecular structure together. Once broken, the material increasingly failed to hold a charge, Zhu told The Current, a UCSB publication.

“Because hydrogen atoms are so small and reactive, hydrogen is a common contaminant in materials,” Van de Walle said. “Now that its detrimental impact has been flagged, measures can be taken during fabrication and encapsulation of the batteries to suppress incorporation of hydrogen, which should lead to better performance.” He said that discovering if lithium has a natural resistance to hydrogen or whether sodium battery fabrication has just not advanced to the same degree are avenues for future research.

The three scientists’ findings appeared in Chemistry of Materials, a journal published by the American Chemical Society, on June 21. Zhu now works for Google, and Peelaers is an assistant professor at the University of Kansas.


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