Ceramic Batteries

EEStor of Cedar Park, Texas (near Austin) says it has developed a ceramic "battery" with extrodinary energy density.

Seasoned scientists at EEStore say they've created a battery made of glass- and aluminum-coated ceramics that could allow electric motors to completely replace the internal combustion engine. The inventors, erstwhile Xerox PARC and IBMmers, boast about the car's efficiency, saying it'll be so cheap it'll be as if gas costs 45 cents per gallon, will drive 500 miles on nine bucks' worth of electricity, and needs just five minutes to completely recharge.

Actually the battery is a capacitor. An ultra capacitor. Which in the old days we used to call a condenser. Two plates of metal separated by paper or oil or something (called a dielectric) that helps multiply the charge storage. The key to higher energy storage (KWh) and higher energy density (KW peak) is better dielectrics.

Current ultra capacitors (double layer) are kind of leaky. The charge bleeds off in about a day or two. Part of the reason for this is that such capacitors are low voltage. Around two and a half volts max. You can stack them for higher voltage, but that reqires equalizing resistors across each capacitor which drain power, besides the inherent drain of the capacitor itself due to its wet chemistry nature.

The EEstor capacitor is made of a material called Barium Titanate. This is a ceramic material with low inherent losses compared to the double layer ultra capacitors. In addition it is not limited to low voltages. Currently Barium Titanate is used extensively in capacitors for filtering high frequencies in electronics and other electronic uses. What this break through does is greatly increase the capacitance for a given voltage permitting a huge increase in energy storage.

So let us do the numbers. The EEstor folks claim to be able to drive 500 miles on $9 worth of electricity. At $.09 per KWh that would be 100KWh. They claim a recharge time of 5 minutes. So the rate of delivery would be 100*60/5 = 1.2 Megawatts. That is a very hefty delivery rate. At 240 volts it would require a service of about 5,500 amps. Multiply that by the number of vehicles filling up at one time and you have one heck of a power station. If the recharge took 15 minutes. The rate would be 400 kilowatts and the current at 240 volts would be about 1700 Amps. Still pretty hefty. If it was charged in 4 hours the power would be 25 Kw and the current would be a reasonable 110 Amps. That is near what most house service entrances can provide although some newer houses have 200 Amp service.

The weight of the EEStor capacitor is supposed to be 1/10th the weight of an equivalent lead acid mattery. For a 500 mile range unit (110 wh/mi) the weight would be 400 lbs and deliver 52 kwh. So evidently the cost of electricity they were figuring on was twice what I had estimated. Which cuts the currents and kilowatts in half from what I calculated.

A very good use of this technology to start with would be in a plug in hybrid. A 100 mile range would further cut the currents required by a factor of 5 making it possible to charge the capacitors with a 12 amp service in four hours or with a 50 Amp service in one hour. Very feasible without straining the electrical distribution system. It would also double what is considered the feasible range of current plug in hybrids. Such use would also cut the weight requirements by a factor of 5 making the storage come in at about 80 pounds.

Another feature of this technology is that there is no wear out mechanism. Electrochemical batteries are good for about 1,000 full charge/discarge cycles. These capacitors (like other super capacitors) would have no such limitations. Also because there is no chemical change taking place overheating would be less of a problem. It would also eliminate cold weather loss of charge, loss of capacity, and lowered maximum power rate that you get with electrochemical batteries.

The cost is supposed to be in about the same range as lead acid batteries for equivalent energy storage.

Clean Break has some nice links.

The Energy Blog has a good discussion.

One thing you have to watch out for is the smoke and mirrors often seen with new technology promises. It will take a few years to set up a factory once a volume production method is developed. It may take more than a couple of years to get production ramped up. Followed by a few more years to get it designed into products and then produced. Their promise of a vehicle on the road by 2008 probably means a delevelopmental prototype. The soonest you are likely to get one of these babys in a production auto is six years and probably more like ten.