Replaced the dead battery in an old iPod Nano I bought (really wanted a cheap Product Red one) and not even 2 days later the replacement battery expanded. I would call this
Amazon.com: STARTONG 1000mAh 3.7V Replacement Battery for Apple iPod 4th Generation, 616-0183, 616-0206, 616-0215, AW4701218074, ICP0534500,SNO-503450PCN-I : Electronics