Tore down a completely puffed, dead, 0V cell. It was still air tight.
So basically, it's a stack of copper anodes (-) & aluminum cathodes (+) separated by plastic. They're soaked in a fluid. The plastic conducts lithium protons between the terminals, but not electrons. The plastic is why they're called polymer batteries.
The copper sheets (-) are coated in lithium + graphite. The aluminum sheets (+) are coated in lithium + cobalt. The positive lithium protons transfer through the polymer from the - to the + electrodes. The negative electrons transfer through the load from the - to the + electrodes.
Neither the anodes or cathodes reacted violently, even in water. Despite not being air tight, the electrodes stayed completely black when wrapped up. Then some of the anode turned white when completely unwrapped. Since it was completely discharged, it would have been residual lithium. It would have been more exciting if it was fully charged. The cathode side didn't change color.
They're all connected in a parallel fan at the electrode.
Comments
Yes, nice presentation, with good photo documentation (as always).
@ Carl
Thanks, pls do store these little thermites as safely as possibly. I know of case where whole shack was burned down due to these little dirty guys. I even bought one of the aftermath bare skeletons later.
@ Jack
thanks for all the info. Appreciate the effort in this break down.
Cheers
Thanks for the "Heads up " Jack Then air is the oxidizer and moisture in the air could trigger a condition of thermal runaway. You mentioned a white powder forming on some of the plates. I thought it might be some form of oxidation , some grades of aluminum form a white powder when it oxidizes. They look like a giant capacitor that has been un rolled and laid flat. I have two fully charged lypos that are swelling up, something is going on in there? If the relative humidity was high enough and there was a break in the seal that is all it would take to set them off. thanks again Jack . I think l will store my lypos in a metal container from now on.
The anodes would have reacted with water in the air if it was fully charged. If it got hot enough, it could have entered thermal runaway. The odoriferous fluid in the battery seemed to slow down the reaction with air. They're manufactured with no charge, in an open air room full of Chinese factory workers. Only after being sealed & soldered are they charged.
@Morli I like Jack's "lets tear the sucker down and see what makes it tick approach?" If it was any body but Jack
Munroe and Sgt Rick are right it is probably not a good idea to tear them down. We all have lypos we all know they swell up and we all know they burn violently we need to know what triggers it?and when and how should they be disposed of ? Do we all have little fire bombs sitting in the closet that could ignite from spontaneous reaction any time?Are there any lypo Gurus out there that have the answers?
Jack Thanks , great info, now why does it puff when they go bad? is due to some gas build up? Some of my unused LiPo started puffing up, I thought they only do when incorrectly used.
Also when some thing goes wrong, why do they burn violently?
thanks again
Thanks Jack . I had a lypo go bad at 47 hours of use it swelled up I never took it apart to see if a chemical reaction built up a gas inside ? I had another one swell up just from sitting that was not put in use? Happy Easter you guys!