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This is exactly backwards. Traditional Li-Ion batteries have a liquid electrolyte, and Li-Poly have a solid polymer electrolyte. Both batteries consist of anode

This is exactly backwards. Traditional Li-Ion batteries have a liquid electrolyte, and Li-Poly have a solid polymer electrolyte. Both batteries consist of anode/electrolyte/cathode rolled up. In the case of a "pouch" cell, they are rolled up flat, and a cylinderical cell has them rolled up in a cylinder. There is actually no limitation for the shape - you can totally make a Li-ion battery with liquid electrolyte in a prism - many cell phone batteries do this. Li-ion, due to the liquid, needs a hard metal case, whereas li-poly can often get away with a foil pouch. The surface area per volume of a cylinder is less, as well as easier to make structurally sturdy, which means less weight is spent in the casing. Tesla cares more about weight than volume, so this is an acceptable tradeoff.

jacquesm 12y ago
Interesting! I just spent the better part of today reading up on all this because I found it hard to accept that I'd remember something so terribly wrong. Turns out that the names have changed over time to denote various packages and gel/liquid/solid combinations. Wikipedia has a whole page on the subject and it almost seems as if they made the naming of these battery classes confusing on purpose: http://en.wikipedia.org/wiki/Lithium_polymer_battery http://en.wikipedia.org/wiki/Lithium_polymer_battery Enjoy the read, I certainly did and it turns out the situation is a lot more complex (also historically) than I remembered it, but my memory wasn't quite as faulty as you made me feel initially (fortunately!).