powerspring battery case_60MiLi has announced what it claims is “the thinnest iPhone battery in the world”.

Powerspring is a dual-purpose mobile battery case for the iPhone (currently 3G and 3GS only). Not only is it a protective case for the iPhone, it's also a battery charger that MiLi claims doubles the life of the iPhone battery, without needing to plug the iPhone into a wall socket charger.

MiLi Powespring iPhone battery case

It is a one-piece case with a thin rubber hinge connecting the main bottom part, and the top part that flicks back to allow the user to slide the iPhone into the case and then flips back to its original position to secure the iPhone in an all-round case.

The £44.95 Powerspring is compatible with the iPhone 3G and 3GS, with an iPhone 4 version planned.

MiLi Powespring iPhone battery case

MiLi Powerspring specs:

Product Computability: iPhone 3G & 3Gs

Capacity: 1,200mAh (Li Pol)

Standby Time: Up to 230 hours

Talk Time: Up to 3.9 hours on 3G

Internet Use: Up to 3.9 hours on 3G

Audio Play: Up to 19 hours

Video Play: Up to 5.4 hours

L124 X W65 X H18mm