Finally, Better Batteries
Graphite “foam,” nanotech-enabled lithium surge to market.
After years in which consumers and researchers faced sharp trade-offs in weight, safety, and power for high-power batteries, promising variants are emerging. Nanotechnology is enabling a new lithium-ion battery that can unleash five times as much power as existing versions, and this summer, tool manufacturer DeWalt, of Baltimore, MD, plans to sell a line of 36-volt cordless tools that use it. Progress in the field even includes an upgrade to the age-old lead-acid battery.
The new lithium battery – developed by A123 Systems of Watertown, MA, and based on the work of Yet-Ming Chiang, a materials scientist at MIT – is not only more powerful but also recharges to 90 percent capacity in five minutes and lasts through ten times as many recharging cycles as conventional counterparts, the company says. The battery will initially be used in professional-grade tools where bursts of high power are at a premium. But the technology could lead to battery-operated versions of power-hungry devices like vacuum cleaners, lawn mowers – even hybrid cars.
Chiang improved lithium-ion technology with nanotech. As lithium-ion batteries are charged and discharged, they shuttle ions between their electrodes. Shrinking the size of the lithium particles can increase the batteries’ power, but it can also incline them to explode. Chiang started with safer but poorly conductive materials and borrowed a trick from the semiconductor industry – “doping” one material with trace amounts of another – to make them conductive. Then he shrank the doped particles, making it easier for ions to escape. Nail-puncture tests that cause conventional lithium-ion batteries to burn produces only a wisp of vapor, the company says.
A123 Systems is not the only company changing the battery game. Firefly Energy of Peoria, IL, is redesigning lead-acid batteries and developing them for use in military vehicles and lawn tractors. Firefly replaced some of the battery lead with a graphite foam that has a much greater surface area. This cuts weight, extends longevity, and puts the batteries in the same performance category as the nickel-metal hydrides in hybrid cars, says cofounder Mil Ovan.
As yet, no proposed batteries offer the 15-year lifetime needed for hybrids, says David Howell, manager of energy storage research at the U.S. Department of Energy. But Chiang says he is already talking to automakers.
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