I just read an article about Tesla's current Battery Technology director (Kurt Kelty) and his statements about Japanese suppliers being unwilling to take risks. I looked him up and found this 9 minute interview from 2011. He mentions some interesting things, including name dropping Tesla's battery recycling partners (I don't know whether they are still partners) and the fact that Model S battery cells use a different cathode, anode, AND electrolyte than the Roadster.