The non-removable battery is of the lithium polymer (Li-poly) variety, as opposed to the more frequently used lithium ion.

ENGADGET: Motorola Atrix HD review Mobile

The juice pack is a rechargeable lithium polymer battery in the form of a non-slip, soft grip case and offers the following fantastic features...

ENGADGET: mophie launches $99.95 Juice Pack for iPod touch 2G