LiFePO4 was identified as a cathode material for rechargeable lithium batteries by John Goodenough‘s research group at the University of Texas in 1997. Because of its low cost, non-toxicity, the high abundance of iron, its excellent thermal stability, safety characteristics, good electrochemical performance, and high specific capacity (170 mA·h/g) it has gained some acceptance.
In electric vehicles, there is a great demand for good batteries. One of the promissing technologies, not very well known yet, are LiFePO4 batteries. Those batteries offer greater range, power and safety. They provide full power until they are completely discharged, and recharge in just 2.5 hours. LiFePO4 chemistry is also environmentally friendly – it’s the least toxic of all the battery types. Good point, isn’t it?
The biggest company which develops LiFePO4 batteries is A123 Systems. This company is a partner company with GM to develop batteries for the Chevy Volt plug-in hybrid.
The most common source of high-quality LiFePO4 cells from A123 Systems seems to be from taking apart the battery packs of the new DeWalt Lithium cordless power tools. There are a number of tutorials on the net about how to take them apart, and the most efficient way to recombine into appropriate sized packs for RC planes and such.
Here are some links:
RC Groups link list
SLK Electronics page on DeWalt
List price is $160 for a 36V pack (10 cells: $16 per cell.) People are buying packs from eBay for about $100. (It looks like the lithium technology is hitting some of the lower voltages now; deWalt’s site says they’re using the “nano” technology in packs as low as 18V.)
(There are some cheaper cells you can buy from some of the Chinese exporters like United Hobbies. Caveat Emptor. I haven’t been paying attention enough to have seen reports of quality or lack thereof from these “mystery sources.”)