This is the Philips Xenium, which has a smartcavity(tm)into which you place a normal, or re-chargeable AAA battery. When you charge the phone, you also charge the battery. It does mean your phone has a rather unsightly bulge at one end, but if you’re the kind of person who values productivity over aesthetics, then this is the device for you.
They also do a wide range of stand alone mobile chargers, but unless you’re in the jungle or a desert (where you’ll probably struggle to get a signal anyway) i can’t quite see the point of em. When you live in the global village you’re very rarely that far away from a power socket, and if you don’t have a charger on you, someone else is bound to. Emerging markets you say? Perhaps, but in countries where a pack of triple AAA batteries cost the equivalent of two months wages (Zimbabwe), talking on your phone a bit longer will probably come lower on the list than feeding your children.