What is te difference between lithium ion and lithium polymer batteries?

Are they different chemically? is it the same thing in a different package? same thing but different nomenclature?

lithium ion is the term used for the umbrella of lithium batteries usually. you've got it right about the packages, usually when someone is talking about a lithium ion they are talking about a battery in a solid metal or plastic case. The lipo's are in polymer sacks. The other difference used to be that li-ion had 3.6v per cell nominal vs 3.7v nominal for the lipo's. New li-ions though usually run at 3.7v. From my understanding the reason why we use lipo in RC is because it saves weight, and also helps with heat issues because the heat wouldn't have a case to flow through, jsut a thin layer of plastic.

The "polymer" in lithium polymer batteries is part of the internal construction, not a sack on the outside of the battery. Each lipo cell consists of many thin layers of material, among which are porous plastic membranes filled with a polymer.

See BatteryUniversity.com for a full explanation.

- Jeff

hrm, I thought all lithium batteries had polymer electrolites. Guess not. Mah bad =)

http://batteryuniversity.com/partone-5.htm

lipo batteries use lithum sheets that look like tinfoil, and polymer sheets that look like plastic wrap. the polymer insulates the lithium from each other to keep it from shorting out, and it's basically just a long strip of each wound into the size of a pack. The discovery channel has a program called "how it's made" and they show you how they are made every once in a while.

so li-ion has a liquid electrolyte or what?

The Li-Ions I have taken apart kind of look like the construction is the same but only rolled in a spiral and put in the can. Thats what it looked like to me. Never taken a Lipo apart but I think they are laid flat and folded arent they.
Bob

hrm, yeah that's what I was thinking. As far as the lipo's, yup that's the way they do it =)