Silicon-nanotube anodes enhance Li-ion batteries

Battery start-up Amprius described how its lithium ion technology, which taps the topology of silicon nanowire anodes rather than carbon-based anodes, boosts energy density ten times more than conventional batteries at this year's Global Press eSummit.

"Electron transport in lithium ion batteries can be greatly enhanced by going to silicon-nanotube anodes," said founder of Amprius, Stanford University professor Yi Cui. "But first you need to overcome the expansion problem with silicon."

Silicon nanowire anodes for lithium ion batteries can handle 10-times the current of conventional carbon anodes, but in operation silicon also expands by as much as four-times, which can cause conventional topologies to fail. The solution, according to Cui, is to use sparsely spaced nanowires with a mechanical clamping layer on top, which accommodates the expansion without breaking the anode.

Amprius' current prototypes not only offer ten times the energy density, but also can be charged-and-discharged in thousands of cycles instead of the hundreds of cycles typical of conventional lithium-ion batteries.

Amprius is manufacturing its new batteries in China and promises that its first customers will be delivering cell phones with expanded lifetime battery by 2014, with automobile batteries slated to follow in a few years.

- R. Colin Johnson
??EE Times