Hi
Now adays another type of lithium batteries have come up in market which claim to be better in performance than li-ion batteries, they are called li-po batteryies or lithium polymer batteries. You can also check for them if you want high power compact sized batteries. Most odf them are rechargeable as well.
You can get these batteries oveer online shoppind sites like amazon, ebay or you can get it from local markets like bhagirath place market in chandini chowk delhi.