Eggshells for Energy Storage

Photo: Getty Images

7 December 2012—Owners of electric cars may soon be driving on eggshells, if David Mitlin has anything to say about it.
Mitlin, a professor of chemical and materials engineering at the University of Alberta, in Edmonton, Canada, is working on a way to turn waste eggshell membranes and egg whites into materials for high-performance supercapacitors. Supercapacitors offer high power density, charging and discharging far faster than rechargeable batteries. Unfortunately, they store much less energy. Mitlin thinks the membranes inside eggshells could help crack that problem.
“If you could keep the very nice power of a supercap but extend the energy density even to be that of a mediocre lithium-ion battery, you’d really enable the applications world in the automotive sector and in consumer products,” Mitlin told attendees at the Materials Research Society’s Fall Meeting in Boston last week.
Supercapacitors are electrochemical devices that store a double layer of charge on activated carbon as electrodes. Mitlin and postdoctoral fellow Zhi Li propose replacing the activated carbon with eggshell membranes from certain industrial chicken farms. These farms provide eggs yolks for the production of medicine and cosmetics but discard the shells.

Source:IEEE

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Smartphone Battery Breakthrough Coming … In 3 to 5 Years

Although iPhone 4S battery drain was a real problem, it also brought up the need for a smartphone battery breakthrough--something so significant that you'll never have to worry about getting through the day on a single charge, even if the battery's not behaving properly.
The good news is that a true breakthrough is on the way, and promises week-long battery life and 15-minute recharge times. The bad news is that this technology is still three to five years away from the market.
Researchers at Northwestern University worked with the same lithium-ion batteries found in today's smartphones. But by layering clusters of silicon in between the graphene sheets that make up one side of the battery--known as the anode--the researchers were able to pack in a lot more lithium.
Scientists have already tried using silicon as a replacement for carbon-based graphene sheets but, in previous approaches, it expanded and contracted too dramatically, causing fragmentation that reduced capacity. Apparently the sandwiching of silicon between graphene solves that problem.
The researchers also poked tiny holes in the graphene, providing a shortcut for the lithium to travel through and be stored by a reaction with the silicon. Essentially, the unique use of silicon is solving two problems at once.
This breakthrough sounds particularly interesting to me because it's still based on lithium ion batteries. When I last ranted about smartphone battery life when the iPhone 4S faced problems, I pointed to new approaches like kinetic charging, photovoltaic cells or lithium-sulfur batteries. But Northwestern researchers aren't working on entirely new methods. They're just drastically improving the type of batteries that smartphones use already. Let's hope it gets to the real world in time for the iPhone 6S.

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