Green Battery: Wood-Origin Nanobatteries to Breakthrough U.S. Research
Scientists have developed a thin, long-lasting, efficient environmentally friendly battery that uses wood as its backbone.
The components in the battery tested by scientists at the University of Maryland are a thousand times thinner than a piece of paper.
The device uses a sliver of wood coated with tin as its substrate, an advantage over current batteries that often use stiff, non-flexible substrates that are too brittle to withstand the swelling and shrinking that happens as electrons are stored in and used up from the battery.
Liangbing Hu, Teng Li and colleagues have turned to wood fibers from trees.
"The inspiration behind the idea comes from the trees," said Hu, an 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."
They used wood as the base of an experimental sodium-ion battery, choosing sodium over lithium, as many rechargeable batteries do, makes the battery environmentally nonthreatening.
Sodium does not store energy as efficiently as lithium, so scientists do not use such battery in cell phone-instead, its low cost and common materials would make it ideal to store huge amounts of energy at once - such as solar energy at a power plant.
In lab experiments, the team noticed that after charging and discharging the battery hundreds of times, the wood ended up wrinkled but intact. Computer models showed that that the wrinkles effectively relax the stress in the battery during charging and recharging, so that the battery can survive many cycles, putting it among the longest lasting of all sodium-ion nanobatteries.
"Pushing sodium ions through tin anodes often weaken the tin's connection to its base material," said Li, an 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."
Batteries of this type would be best suited for large-scale energy storage applications such as wind farms or solar energy installations, the researchers said.