A123 Systems sounds like an extermination company named to be first in the phone book, but it’s a spin off from a research lab at MIT that’s going to make a big difference. The company is really named after one of the equations that is responsible for the breakthrough it is commercializing.
Right now our laptop computers, cordless tools, and Tesla Roadsters all use lithium ion batteries because they have the highest energy to weight ratio available. On the downside, they lose up to 20% of their capacity per year no matter how well you treat them, and impurities introduced in the manufacturing process can lead to thermal runaway if the cell is overcharged (also known as bursting into flames).
A Tesla Roadster has 6800 li-ion cells. They have a battery management system that should keep the problem confined to one cell. They haven’t had any problems in their crash tests, but a battery that didn’t tend to catch on fire would be a big improvement.
A123 Systems uses some nanotech magic that results in a cell that fails gracefully. This video (from VentureOne) shows a puncture test of A123’s battery followed by a traditional lithium ion.
1 minute. Link to Video
Most li-ion batteries have a graphite anode, but lots of different materials are used for the cathode. Selecting a cathode material is a balance between total energy, maximum power, cost, and safety.
A123 Systems is using an iron phosphate cathode which has rarely been used. It is inexpensive and one of the safest materials available, but it doesn’t conduct electricity well - fairly important in a battery. A123’s nanotech magic changes the lattice structure of the iron phosphate atoms so that the lithium phase change happens more easily, and the cathode becomes a better conductor. That means the system isn’t stressed as much. Less stress means the batteries will last 7000 charge cycles vs 500 for traditional li-ions. Another happy effect is a lot more power: 2X the energy density and 5X the peak power. They also recharge up to 90% in 5 minutes.
Their batteries are already being sold in DeWalt 36 volt cordless tools, and the Chevy Volt will use them. Last year, A123 Systems bought a company called Hymotion. They make plug in upgrade kits for hybrid vehicles. A Hymotion pack for a Prius mounts in the spare tire well, and extends it’s fuel efficiency to 150 miles per gallon equivalent.
