Silicon Could Give Lithium Ion Batteries 10X More Capacity
Researchers are reporting they have developed a new material made from three-dimensional, highly porous nano-silicon that could give future lithium ion batteries a ten times higher capacity than they currently have.
The storage capacity of current generation lithium ion batteries remains a bottleneck for the widespread adoption of electric cars due to a perceived limited driving range. Although we could argue whether a 100-130 mile range really is that much of a limitation or not, perhaps the better solution is to be able to ignore that argument altogether by increasing battery capacity.
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The main reason current lithium ion batteries have a relatively low storage capacity has to do with the type of anode the batteries use. A lithium ion battery consists of two main parts: a lithium metal oxide cathode and, currently, a graphite anode. During charging the lithium ions migrate from the metal oxide to the anode and get stored between the graphite sheets for later use. When power is needed, the lithium ions discharge back to the cathode.
The graphite anodes currently in use have a low capacity for storing lithium ions, and it is this problem that gives the batteries a low overall storage capacity. Researchers have realized for a while that if the graphite was replaced with a micro-porous silicon structure (somewhat like a nano-sponge made of silicon), the holding capacity of the anode could be increased by ten times.
The problem with this approach is that, up til now, the silicon has easily cracked and pulverized as it was loaded with lithium ions during the charge cycle.
But, as published in the current issue of the journal Angewandte Chemie International (1), a team of scientists from South Korea has discovered a way to bulk produce these nano-silicon sponges so that they can withstand repeated charging and discharging cycles. Not only does this new material have a much higher charge capacity, the nature of its nano-structure allows for rapid charging and discharging.
It’s not clear how long it might be for this material to reach commercialization, but this breakthrough certainly seems promising in the quest to develop higher and higher battery storage capacities.
(1) Angewandte Chemie International Edition, doi: 10.1002/anie.20080435
Image Credit: From the journal article in Angewandte Chemie International
Source: Eurekalert
This seems to be great. But Why there´s so much time between studies and the commercialization of these batteries. I have heard also about some great findings with lt-ion by some other universities and countries… and these findings can change at all (to place just one example) all electric car indutry. Can you image what could be the one-charge range of an electric car in Kms ????? Can we get an aproximate ???
And when will we see any practical implementation of this technology?
Yet more vaporware. Put it in a working product and make me believe…
Let’s not forget disposal of the broken down batteries. They are, after all, Hazardous Waste…….
Question. If the capacity is 10 times, or 1,500 miles, does that mean that somebody can make a cross country trip with such a car? I’ve done the west coast/east coast run probably a hundred times or more and that means at least 1,500 miles each day (usually more). What is the recharge time?
Just trying to understand if this means the reach of such a car would be effectively equal to a gas driven vehicle.
Density isn’t the only reason that Lithium Ion battery powered cars aren’t being mass produced. Cost is another issue. While I’m sure it’s technically possible to create a car with a 100 mile range based on Lithium Ion batteries, it’s going to be quite expensive. I understand this is one of the reasons that many existing hybrids use NiMH batteries. Safety is another issue - LiIon have more issues with overheating and fires.
So, if a future battery technology is able to produce cells with 10 times the energy density for twice the cost of current Lithium Ion batteries, not only would this allow longer ranged vehicles but it would also allow for cheaper vehicles with similar ranges that are possible today. In my opinion that’s an even bigger obstacle to the widespread use of electric cars. Once they can compete on price with gasolene powered cars they will be much more attractive to the average person.
Hmmm. I think there is actually a shortage (or very nearly) of highly pure electronics grade silicon. What grade of silicon purity does this micro porous silicon structure require? If it requires the highly purified stuff then the cost of these batteries has the potential to be much higher when compared to current generation Li-ion batteries.
Excellent point Josh. I don’t know the answer to that, but I’d imagine it doesn’t need the highly purified silicon due to the method of manufacture of the anode with acid etching and what not.
“Stanford’s (silicon) nanowire battery holds 10 times the charge of existing ones”
December 18, 2007
http://news-service.stanford.edu/pr/2007/pr-nanowire-010908.html
nanowire forest vs. sponge
Actually, no, we won’t get 10x battery capacity from the 10x anode improvement.
To quote the guy who started by experimenting with silicon nanowires
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Compared to current A123 or LG Chem cells, if they used your silicon nanowire technology would they be able to store 10 x as much energy?
Yes, that the idea, they would be able to hold 10 x as much energy in the same amount of volume or same amount of weight. Of course the battery consist of two electrodes, the anode and cathode, you would also like to improve the cathode too to make it happen.
If you just changed the anode to nanowire and not the cathode, would the cathode limit the energy potential storage?
If you improve the anode that just means for the same weight or same volume of the batteries you can use less anode materials, you can use the extra weight and volume to hold more cathode materials and you also improve the battery significantly.
If I take a current battery’s cathode materials and combine i with silicon nanowire anode, I can significantly improve its performance.
Will that give you a ten-fold improvement?
That will not give you ten-fold but it will give you several fold improvement.
In terms of energy density?
Yes.
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My reporting for MIT Technology Review confirms what GSP is saying: anode improvement can help, but will not have full impact until cathode development catches up. Graphite anodes already have a charge density roughly double that of the average lithium battery cathode. See “Realizing Lithium Battery Potential” at http://www.technologyreview.com/energy/21750/.