March 11, 2009
World Science staff
Engineers say they’ve found a way to move energy faster through a well-known battery material, possibly paving the way for smaller, lighter batteries that recharge in seconds rather than hours.
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Engineers say they’ve found a way to move energy faster through a well-known battery material, possibly paving the way for smaller, lighter batteries that recharge in seconds rather than hours. The advance could also benefit car batteries, which usually take hours to charge, according to engineers. (Image courtesy GM) |
Modern lithium rechargeable batteries can pack plenty of charge into a small space, but are slow to take up and discharge that energy. This drawback means that, for example, an electric car battery can move the auto at a moderate highway speed for a long time, but acceleration is sluggish, Ceder noted.
Scientists traditionally thought such pokey performance was due to slow movement of the particles that carry electric charge across the battery—charged atoms and electrons. But through a series of computer calculations, Ceder and colleagues found that this wasn’t exactly the problem, at least not for a well-known battery material, lithium iron phosphate.
The real difficulty, the group found, is that the charged atoms can only cross through the material through tunnels accessed from the surface. If the particle lies directly at a tunnel entrance, it slips right in, but otherwise it gets stuck.
Ceder and Byoungwoo Kang, a graduate student, devised a solution: a new surface structure that lets the particles, called ions, move quickly around the outside of the material. Like a beltway around a city, this diverts ions right into the tunnels. The result was a small battery that could be fully charged or discharged in 10 to 20 seconds. By comparison, it takes six minutes to fully charge or discharge a cell phone made from the unprocessed material.
Ceder said further tests showed the new material degrades less than do other battery materials when repeatedly charged and recharged. This could allow smaller batteries, as less material is needed for the same result. The advance “may open up new technological applications and induce lifestyle changes,” Ceder and Kang wrote.
