I replaced my Sandisk Clip Zip battery with LP-402933-IS-3 BATTERY, LITHIUM POL, 3.7V, 300 MAH BAK
- http://uk.farnell.com/bak/lp-402933-is-3/battery-lithium-pol-3-7v-300-mah/dp/2077884 (It’s this battery, but I had to buy it from sinuss.nl due to me not being a company…)
I have rockbox installed on it, which is an awesome piece of custom firware for selected mp3-players. The most recent update of the rockbox firmware should double the battery life!
https://www.rockbox.org/wiki/ReleaseNotes314
I have used the Sandisk Clip Zip for some years now and I am really happy with the product in combination with rockbox! The mp3-player is really small, has an outstanding battery life, can play lossless audio files and features GAPLESS PLAYBACK. Would definitely replace battery again for this piece of ART. 
You can check my video for the proof of functioning:
https://www.youtube.com/watch?v=f7rDINoQO7g&feature=youtu.be
Cheers!
Tatami112
