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Doped nanotubes boost lithium battery power three-fold

Stringy silicon also recharges in minutes

A team from the University of Southern California (USC) has built a lithium battery that provides three times the power capacity of conventional designs, with a recharge time of just ten minutes and a predicted long life-span.

"It's an exciting research. It opens the door for the design of the next generation lithium-ion batteries," said Chongwu Zhou, professor at the USC Viterbi School of Engineering, who led the team that developed the battery, in a statement.

Many lithium batteries, particularly in the mobile space, use graphite as an anode but this has limited capacity. Silicon is an obvious replacement and works well, but suffers from performance issues after repeated charging cycles, so the team decided to see if carbon nanotubes are more effective.

The nanowires were doped with boron and a commercially available alginic acid sodium salt solution, rather than the more commonly used polyvinylidene fluoride. The resulting battery performed better than expected and the design looks to be a viable player for use in everything from mobile phones to electric cars.

"The porous silicon nanowires exhibit superior electrochemical performance and long cycle life as an anode material in lithium ion batteries when combined with the alginate binder," the team wrote in a paper published in Nano Letters.

"Even after 250 cycles, the capacity remains stable above 2000, 1600, and 1100 mAh/g at current rates of 2, 4, and 18 A/g, respectively. Our best battery has recorded 2000 cycles with a capacity remaining above 1000 mAh/g.

The team says the battery needs further testing but shouldn't take more than two or three years to get into volume production. Boeing could certainly be one firm that should be interested, given its problems with inflammable 787 Dreamliners, but there will be plenty of other takers as well.

Battery technology hasn't developed with the same speed as the electronics it powers, and manufacturers are desperate for something that can allow them to run systems at full grunt and not leave users powerless. This new research could bring that a little closer, but there have been a lot of false alarms along the way. ®

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