Tesla Motors has never officially announced who supplies the lithium ion cells used in the Roadster's battery pack, but it does have an agreement with Panasonic to supply cells for the Model S.

ChemID 1580 (Sanyo) and ChemID 2107 (Panasonic). They are shown with different cathodes ... that will list out the best match for your cells. Can we assume that a higher numerical value for ChemID ...