June 19, 2013
New Battery Made From Wood Is Environmentally Friendly
[ Watch the Video: University of Maryland Scientists Create Battery Using Wood ]
Lee Rannals for redOrbit.com — Your Universe Online
The scientists developed a battery made from a sliver of wood coated with tin that could be a game changer as a long-lasting, efficient and environmentally friendly energy source. They said their device is 1,000 times thinner than a sheet of paper.
"The inspiration behind the idea comes from the trees," said Liangbing Hu, an assistant professor of materials science at the University of Maryland. "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."
Conventional batteries use stiff, non-flexible substrates, which are too rigid to release the stress that occurs as ions flow through the battery. The researchers saw that wood fibers from trees were supple and naturally designed to hold mineral-rich water, similar to the electrolyte in batteries. They decided to explore the use of wood as the base of an experimental sodium-ion battery.
During lab experiments, the device performed successfully through 400 charge-discharge cycles, which put it among the longest lasting of all sodium-ion nano batteries. The batteries using the new technology would be best suited for large-scale energy storage applications, like wind farms or solar energy installations.
The team noticed when charging and discharging the battery hundreds of times that the wood ended up wrinkled, but intact. Computer models showed the wrinkles effectively relax the stress in the battery during charging and recharging so the battery can survive many cycles.
"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 play a big role in trying to reduce the carbon footprint. However, they must be efficient in order to be effective in places like wind farms. Researchers from Stanford University said in March the best way to reduce a battery's long-term, energetic cost is to improve its cycle life. They said the hydroelectric storage method worked out better than five other battery technologies.
“Pumped hydro storage can achieve more than 25,000 cycles,” Charles Barnhart, a postdoctoral fellow at Stanford´s Global Climate and Energy Project (GCEP) and lead author of the study, said in a statement. “That means it can deliver clean energy on demand for 30 years or more. It would be fantastic if batteries could achieve the same cycle life.”