The picture shows the wood  fiber after cycling.  Photo 
courtesy of the Maryland  NanoCenter.
The picture shows the wood fiber after cycling. Photo courtesy of the Maryland NanoCenter.

A battery made from trees? It’s not as outrageous as some would think.

A team of engineers at the University of Maryland have developed a battery made from a sliver of wood coated with tin. The environmentally friendly battery uses sodium and can store large quantities of energy at once, though not as efficiently as lithium. The target application therefore for this type of battery is grid-scale energy storage, such as solar energy installations.

“The inspiration behind the idea comes from the trees,” said team member Liangbing Hu, assistant professor of materials science. “Wood fibers that make up a tree once held mineral-rich water, and so are ideal for storing liquid electrolytes, making them not only the base, but an active part of the battery.”

Compared to traditional batteries which use stiff, brittle substrates making them unable to withstand the shrinking and swelling from the ion flow, the research team found that the wood fibers remained supple, even after more than 400 charging cycles. This makes it one of the longest-lasting sodium-ion nanobatteries, the research team said.

“Pushing sodium ion’s through tin anodes often weaken the tin’s connection to its base material,” said Teng Li, associate professor of mechanical engineering. “But the wood fibers are soft enough to serve as a mechanical buffer, and thus can accommodate tin’s changes. This is the key to our long-lasting sodium-ion batteries.”

The research team used wood fibers from southern yellow pine. Their paper, “Tin Anode for Sodium-Ion Batteries Using Natural Wood Fiber as a Mechanical Buffer and Electrolyte Reservoir,” appears in the journal Nano Letters.

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