Silicon to improve batteries tenfold

Written by Clive Webster

November 16, 2011 | 15:37

Tags: #battery #graphene #li-ion #lithium-ion #silicon #smartphone

Companies: #bit-tech

A recent paper in the Advanced Energy Materials journal details a new technology to lower the charge time of a lithium-ion battery to around 15 minutes and increase battery life to around a week. Apologies if that link doesn’t actually link to the paper – we think it does, but even the abstract has us baffled.

The helpful chaps and ladies at Northwestern University have decoded the science for us, so we do at least know something about the new technology. It relies around adding silicon layers to the layers of carbon-based grapheme sheets that comprise the anode of a typical lithium-ion battery.

The huge increase in battery life, and the massive drop in charge time, is possible because a silicon atom can accommodate four lithium ions per atom while it requires six carbon atoms to accommodate a single carbon atom in conventional designs.

It’s the flow of lithium ions from the anode to the cathode through an electrolyte material that creates the electrical energy, so the more you can pack into the anode, the more charge can be stored. Equally, the quicker you can get lithium ions from the cathode back into the anode, the quicker a battery will recharge.

Previously, silicon was seen as a poor material for an anode, as it suffered from ‘fragmentation’, but by interlacing silicon and grapheme layers this problem has been solved. Tiny holes – 10-20 nanometres wide - are drilled in the grapheme sheets to help the lithium ions access the silicon.

Harold H. Kung, the lead author of the paper, said, ‘Even after 150 charges, which would be one year or more of operation, the battery is still five times more effective than lithium-ion batteries on the market today.’ As well as avoiding the issues of batteries wearing out over time and massively reducing charge time, the technology could lead to a tenfold shrinking in battery size for the same power output or ten times the capacity for the same size, or anything between those two extremes.

While the shrink in size will suit tablets, smartphones and other mobile devices, the increase in capacity and huge decrease in charge time could be useful for battery-powered vehicles. However, silicon-graphene lithium-ion batteries are said to be 2-5 years away from mass production.

Excited by the future, or just annoyed that it’s taken this long for a big advance in battery technology? Let us know in the forum.
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