October 13, 2010
Silicon Lithium Battery Could Increase Capacity

A promising approach using silicon might boost lithium battery capacity by a factor of 10.

A team of Rice University and Lockheed Martin scientists has discovered a way to use simple silicon to radically increase the capacity of lithium-ion batteries.

Sibani Lisa Biswal, an assistant professor of chemical and biomolecular engineering, revealed how she, colleague Michael Wong, a professor of chemical and biomolecular engineering and of chemistry, and Steven Sinsabaugh, a Lockheed Martin Fellow, are enhancing the inherent ability of silicon to absorb lithium ions.

They believe they've figured out how to prevent silicon from cracking after a couple of cycles of absorbing and releasing lithium atoms.

Silicon has the highest theoretical capacity of any material for storing lithium, but there's a serious drawback to its use. "It can sop up a lot of lithium, about 10 times more than carbon, which seems fantastic," Wong said. "But after a couple of cycles of swelling and shrinking, it's going to crack."

Other labs have tried to solve the problem with carpets of silicon nanowires that absorb lithium like a mop soaks up water, but the Rice team took a different tack.

Their approach might increase lithium battery storage capacity by an order of magnitude.

With Mahduri Thakur, a post-doctoral researcher in Rice's Chemical and Biomolecular Engineering Department, and Mark Isaacson of Lockheed Martin, Biswal, Wong and Sinsabaugh found that putting micron-sized pores into the surface of a silicon wafer gives the material sufficient room to expand. While common lithium-ion batteries hold about 300 milliamp hours per gram of carbon-based anode material, they determined the treated silicon could theoretically store more than 10 times that amount.

We'd all benefit from a large increase in battery capacity. Of course laptop computers and cell phones would work much longer between charges. But also, an order of magnitude increase in battery capacity would make electric cars feasible for most uses. Oil price worries would gradually fade away. We'd breathe cleaner air and cars would last longer with less need for maintenance.

Share |      Randall Parker, 2010 October 13 11:04 PM  Energy Batteries

Engineer-Poet said at October 15, 2010 11:47 AM:

Note that the capacity improvement is only for one electrode, the anode.  The cathode, electrolyte, separator and casing are unchanged.

Phos said at October 15, 2010 12:10 PM:

Good comment E-P. I know my tendency is to equate this with a 10 fold increase in energy capacity per kg for the battery.

When combined with recently developed anodes with increased capacity, this will probably lead to a doubling of capacity.

Wolf-Dog said at October 17, 2010 4:39 PM:

Even doubling the charge capacity of the current lithium-ion batteries will be a major breakthrough because it will then become realistic to expect a 250 mile range from electric cars. The only issue will be to lower the price of these batteries, and this requires more funding. If only the US government invested just 0.2 % of the GDP on battery research, within less than 10 years we would have affordable electric cars that are mass produced. Right now Nissan Leaf (and probably also the research cars of Ford) have a range of 100 miles per charge, but these are still expensive due to the batteries.

Engineer-Poet said at October 18, 2010 9:24 AM:

I'd take a halving of the bulk and cost of Li-ion cells so that the practicalities of buying and packaging them make them the obvious solution.  It doesn't really matter if things go toward the Volt, Leaf or Better Place model, electrification is good.

Dowlan Smith said at October 19, 2010 6:16 AM:

One non technological problem is in the assembly of the various patents into breakthrough products. Economics has the concept of the "tragedy of the Commons" where competition to use resources with no owner leads to over-use and depletion or destruction of the resource.) A recent EconTalk podcast dealt with the reverse of the "tragedy of the Commons" scenario where over-privatization with its fragmentation of rights leads to under-use of a resource.

The difficulty is assembling dozens or hundreds of patents into a usable product can halt the production of a technology or even dissuade research into otherwise promising venues.

codebreaker said at October 19, 2010 6:31 PM:

we should have much smaller cars that don't go as fast, with room for bicycles on the streets. this kind of stuff needs to be legislated because not many people want to be the first with the small car and the bike.

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