MIT Engineers Develop Li Battery That Charges in Seconds
Researchers at MIT have developed a solution to one of the long standing problems of battery technology - charging time. Although rechargeable lithium batteries are ideal because they have a high energy density (meaning they can store a lot of charge), the downside is that they have slow power rates, making charging and discharging a sluggish process. MIT Professor of Materials Science and Engineering Gerbrand Ceder and graduate student Byoungwoo Kang have discovered a way to speed up the process.
Scientists have long thought that the power rates of lithium batteries were slow because the lithium ions responsible for carrying charge across the battery material simply can't move quickly. About five years ago, Ceder and a colleague ran computer simulations using lithium iron phosphate, a well-known battery material. The results predicted that the lithium ions should actually be moving extremely fast. Ceder figured "If transport of the lithium ions was so fast, something else had to be the problem." Further research showed that the ions could move extremely fast, but only through tunnels that could only be accessed from the surface of the material. If the ion happens to be in front of the tunnel it will travel through it, if not however, the ion will move slowly because it cannot move to access the tunnel. The solution lied in developing a way for ions to move across the surface and access these tunnels.
Ceder and Kang developed such just such a way by altering the surface structure to allow the ions to move quickly across the surface, in effect creating "beltways" much like those that surround cities. When an ion traveling along a beltway reaches a tunnel it is diverted into it. Ceder and Kang used this technique to build a small battery that could be charged and discharged in 10 to 20 seconds. The same size battery built in the traditional manner took six minutes to fully charge. The new structure also causes the battery to degrade much less than traditional batteries with multiple charges and discharges. This could result in smaller lighter batteries because less material is required. According to Ceder and Kang, "The ability to charge and discharge batteries in a matter of seconds rather than hours may open up new technological applications and induce lifestyle changes."
Ceder also notes that, since this is not a brand new material but rather a change in the production process of an already well known material, the new technology could make it to the marketplace within two to three years.
[via MIT]
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