Dear Student ,
Mobile generally has lithium ion battery which is written as Li-ion if you see the back side of your battery.
It is a kind of rechargeable battery with efficiency ranging from 80-90%.
It consist of three parts
1) Positive electrode - Metal oxide (Lithium Cobalt oxide or lithium iron phosphate or lithium manganese oxide)
2) Negative electrode - In general graphite is used.
3) Electrolyte - Salt of lithium in an organic solvent. ( organic solvent used is ethylene carbonate )
Regards