so the risk of catching fire is practically zero...
Not quite zero - it has happened more than once. There is some thought that these instances were due to after market batteries, but that's irrelevant to the point that those people shoved their phones down their pants.
More relevant, I would have thought, is that this IGG affair would carry the appropriate test marks (whereas the 'light-up' batteries above probably didn't). As such they would be as safe as original batteries - otherwise they wouldn't pass the tests - so no more likely to burst into flames. If the
don't pass those tests then you a) know you're buying rubbish and/or b) they wouldn't be able to complete the project. Either way, if the batteries are a liability they would be in really
really deep shit.
I wouldn't worry that the batteries fail catastrophically. I would worry that my money disappears because they can't ship safe batteries.
Incidentally, BBC Click! showed this project over the weekend. They (Click!) tend to be near the bleeding edge but generally don't show hopeless stuff that doesn't have a chance. Not sure if that means anything regarding this project - maybe they got hoodwinked, or they have new and more gullible researchers just joined