Shit... Ok, stay away from it and do not approach it for a long time, preferably atleast a day. If what you said is true it is venting extremely dangerous fumes that permanently dissolve your lungs.
No idea myself, I’m 100% positive I didn’t puncture it as I’ve perfected pulling laptop packs apart at this stage.
I took a pic (using a big zoom lens so wasn’t near the battery), the arrow points to where it was bubbling (shiny spot), I circled what looks like a dark discoloured patch that was on this cell and the adjoining cell when I removed them.
The four other cells are not discoloured like this and measure above 3.5v- on that note does anyone see any reason I shouldn’t use these cells that measure well?
Actually, the electrolyte solution in the cells isn’t that nasty. It is a flammable solvent, though. Once a cell is discharged to near zero, the chances of it having enough energy left in it to ignite the electrolyte is rather small. The salt-water douche is a good way to discharge the cell fairly slowly and safely. I prefer a, uhhh, more direct method. J)
If there was HF in there, the shell and copper and aluminum electrodes would be dissolved. You might get some HF if the electrolyte torched off… would depend on the electrolyte.
I have a friend that tortures batteries for a living. He would be long dead by now if there was something really nasty going on.
How the hell can a cell start to bubble? Are we sure its venting or just getting really hot?
I'd let it sit outside for a few days (dont throw it onto the lawn and run over it with a lawnmower though) and then try the saltwater method. If you have something like this, you should be really safe: