There are TWO major developments in this battery design:

1) Research at the University of Texas (I think it was UT, but could have been another in Texas) developed the basic LiFeP04 battery design using a solid bar of iron phosphate as the cathode.

2) Further research at MIT realized the iron phosphate could be formed into a crystal-like series of micro-scale cylinders (which they call Nanophosphate), which increases the actual surface area of the cathode by an order of magnitude. Imagine the difference in surface area between a solid cylinder and a hollow cylinder (A=2*Pi*r^2 + 2*Pi*r*h for solid, vs 4*Pi*r^2 for hollow), then expand that increase by millions of millions of times as the the size of the actual tubes decreases. The final product is a TREMENDOUS increase in the actual surface area of the cathode.

The actual rate of reaction depends upon the number of molecules that are capable of reacting at any given time. Because the cathode of the A123 is significantly larger, a significantly larger number of individual molecules are capable of reacting at a given time. Because of this the cell can deliver a very high current at a high voltage. This is purely logical from my standpoint.

The potential of these two developments is so great that the two professors and one post-doctoral student at MIT who developed the nanophosphate cathode started their own company to bring these to market, and that company is A123 Systems. ONLY A123 Systems batteries (and officially licensed cells) have the nanophosphate cathode that makes the LiFePO4 work so well. They were so successful they purchased Enerland Batteries (think Flightpower, Polyquest, and other famous cells...) to be their manufacturer to keep up with the demand.

Other LiFePO4 cells are similar but cannot provide the high current at high voltage. Look for true A123 cells soon in all the hybrid cars to replace the NiMH cells currently used. Talk about a revolution...

OK, that is enough for today.