In recent years, the battery technology achieved a tremendous progress, encouraged by the number of new mobile devices. Were there earlier essentially only lead and NiCad batteries, so you have to do these days with a much larger number of technologies.
Lithium Ion, Lithium Polymer, NiMh to name a few. All require special chargers that are on the physical characteristics of the battery types matched,
Here are some links to lithium ion (Lion) chargers

Here you may find Circuit, Basics, Schematic Diagram and DIY Kit components for Lion charger