New technology extends the life of lithium-ion batteries

Nexeon, a spin-out of Imperial College London, has developed production methods for its lithium-ion batteries at a new pilot plant in Oxfordshire, with the aim of keeping costs equal to those of conventional carbon anodes.

The technology allows batteries to hold ten times the charge of other models because silicon anodes can hold more lithium ions than carbon ones and could be used in electric vehicles or consumer electronics.

But previous attempts to use silicon have suffered because the connections between atoms break down through repeated charging, leaving isolated regions of material.

Nexeon’s design involves creating a structure of tiny interwoven strands of silicon, one fifth of a micron in diameter, which prevents the material degrading in the same way.

‘If one connection is broken there are a million others so you don’t get the cracking up,’ said Imperial’s Prof Mino Green, inventor of the technology and Nexeon’s chief scientific officer.

To create the strands, tiny hemispheres of silver are deposited on particles of silicon and hydrofluoric acid is used to etch down through the remaining exposed silicon, leaving a structure resembling a hedgehog.