Hybrid cars are at the intersection of nanotechnology and battery technology research

Posted on June 1, 2007

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Nanotechnology isn’t a technology in and of itself so much as it’s an enabling technology. What this means is that the science and technology of the very, very small (aka nanotechnology) enables radical changes across a massive number of other technologies and fields. For example, nano-scale particles of gold can be combined with a chemical marker to turn from red to blue (or vice-versa) in the presence of toxins.

However, as PBS’ NewsHour program reports, another application of nanotechnology is dramatically improved batteries and electronic components called “ultra-capacitors.” The amount of energy that a battery can store is directly proportional to the surface area of the electrodes, meaning that if you double the surface area of the electrodes, your battery can store twice as much energy and either operate twice as long, run twice as hard, or, if you could figure out a way to fold up or roll all that area into a smaller package, make the batter smaller and lighter.

To give you an example, Tesla Motors put out a white paper on their electric roadster’s battery pack in which they say that they’re using a battery pack composed of approximatley 6800 lithium-ion batteries that are each a little bigger than a AA battery. The pack weighs about 450 kg (993 lbs), stores about 56 kilowatt hours (kwh) of electric energy and delivers up to 200 kilowatts of electric power. According to this interview of AltairNano CEO Alan Gotcher, the electrode area for lithium-ion batteries is about 1 square meter per gram of electrode material. Applying this to the Tesla battery pack (and assuming that only about 50% of the pack’s mass is actual electrode material), we end up with 225,000 square meters. To put this into perspective, this is about 55.6 acres, a little less than 1/4 square kilometer, or about 30 soccer fields.

Using nanotechnology, however, gives us the opportunity to increase this area dramatically. According to Alan Gotcher, his company estimates that they can increase the area of their lithium-ion batteries by a factor of 40-200 using nanotech-based battery electrodes. To continue using the Tesla battery pack as an example, this would mean that their existing battery pack would be more like 9-45 square kilometers of electrode area, or 120 to 600 soccer fields. Tesla Motors estimates that they can get over 200 miles per charge – this could increase to something like 8000-40,000 miles per charge using nanotech. Or, more likely, Tesla Motors could keep the electrode area roughly the same but save vehicle mass instead, conservatively reducing the battery pack mass by 50% and thus cutting around 475 pounds out of the vehicle.

And this is why companies like Nissan (from the NewsHour story) are so interested in using nanotechnology for electric and hybrid vehicles.

Crossposted: The Daedalnexus, Dr. Slammy in ’08]

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