RE:Interesting Agoracom Post: Is Tesla waiting on nanosilicon Continuing Musk says…
“so the problem with a pure silicon anode is that it is very difficult to have it stay together when you charge and discharge so, one of the things you can do is to add silicon to the carbon anode.
Carbon has only very minor expansion and contraction so it is easy to maintain a carbon anode and have its structure be robust across many charge cycles. And you can throw a little bit of silicon there and the silicon can kind of expand and contract inside the carbon matrix.”
But, as you start adding more silicon it gets harder and harder to maintain the structure of the anode. So our highest energy density cells will use, I don’t know like, 90% carbon maybe 10% silicon or something like that – It’s a small percentage.”
Finally talking about how to produce a pure silicon anode Musk says “there are much higher energy density cells you can get where if you have very precise construction of the anode, a little bit like chemical vapor deposition, you sort of print it like a circuit board situation such that the expansion, it can expand and contract without cracking, then you can get 50% higher energy density than we have in our cars.”