A123
seanseamour on Jan 09 2008
[~jan~~9~]
The future leader in Li-ion automotive batteries ?
I have hesitated until now to publish data regarding A123 as their Iron Phosphate technology appeared close to other companies I had already published, although summarily What strikes me today is the link to the Stanford University nanostructure breakthrough that has demonstrated the ability to multiply by ten the storage capability of Li-ion cells see posting Getting a grip on Lithium-Ion.
What is important here is that the manufacturer tunes the cell to obtain either for higher power or for greater energy density. Total energy determines the vehicle’s range, whereas available higher power determines its acceleration — considering that in a marine environment we have no need for higher power (rubber to road versus prop to water) torque is the constant applied to a propeller whatever the rpm. The link to Dr. Cui’ silicon nanowire enhancement to A123 battery technology is of critical value for future marine applications, all the more of claims of increasing energy density tenfold come true as it offsets one of the downsides of this Li-ion technology.
Iron phosphate may well be the most promising new cathode, thanks to its stability and safety. As already mentioned this is what A123, Gaia and Valence are using in their batteries. The compound is inexpensive, and because the bonds between the iron, phosphate, and oxygen atoms are far stronger than those between cobalt and oxygen atoms, the oxygen is much harder to detach when overcharged. Therefore, when it fails, it does so without overheating.
Unfortunately, however, iron phosphate doesn’t conduct well; to compensate, engineers have to add dopants. Even then, the cells work at a lower voltage than cobalt, so more of them must be chained together to drive a motor. That means iron phosphate battery packs need more interconnections and sensors to control the system. One way around that problem is A123’s use of nanostructures in the cathode. This proprietary method produces better power and longer life than earlier generations of iron phosphate cells, says Andy Chu, a researcher at A123.
As phosphate molecules in the cathode acquire and give off lithium atoms-undergoing lithiation and delithiation-the phase boundary between the two states shifts, just as the boundary between cold water and ice does during freezing. In A123’s nanostructures, Chu says, the molecular lattices of the two states are structurally more similar to each other than in other phosphate cells, so atoms need less time to rearrange themselves. Moreover, because the lattice spacing of the two phases is closer, the physical stress on the cell is reduced, especially in deep discharge and charge. The cells should thus last longer.
It appears that already before the Stanford research announcement A123 has taken a leading position in automotive applications, we previously announced that Continental in Germany was planning to introduce a Li-ion battery in 2008, this will be based on A123 cells, and the company is also in co-leading position with its Korean competitor to supply General Motors’ Volt vehicle.
We will update this as more information arrives, but a look at their website and the current specifications for the 32 series cells is interesting : 32 Series Automotive Class Lithium IonTM Cells: A123Systems recognizes that the impending transportation revolution requires industry-specific solutions. To that end, we have developed two Automotive Class Lithium Ion cells, the ultra high power AHR32113M1Ultra and the more energy dense AHR32157M1HD.
