Battery for Apple iPod Nano 3rd Gen Generation MA978LL/A Silver 4GB 8GB 616-0332 811339015333 | eBay
iPod Nano 6th Generation Teardown - iFixit
330mah Replacement Battery for Apple iPod Nano 1st Generation – Elite Obsolete Electronics
iPod Nano 6th Gen Battery Replacement From Start To Finish. - YouTube
Battery, 400mAh High Capacity Battery for use with iPod Nano Gen 3
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: iFixit Battery Compatible with iPod Nano Gen 2 : Electronics
iPod nano (2nd Gen) Battery - Smartphone Repair Association