In theory, yes. But those usually have electronics in them in an attempt to save you from yourself. So it's unlikely that the thing would fire when you wanted it to without being fooled into believing it was hooked up to a 12v battery in some way.

You can get off brand motorcycle batteries online for like $20. The quality is irrelevant for this application, especially since you probably won't be welding hundreds of battery tabs in a day. The point is that they can reliably deliver enough amperage to weld the tabs while having a low enough terminal voltage to be unlikely to deal either yourself or your cells a mischief.