Julien
It wasn't a good idea. Batteries are often made with acid (like the good old lead-acid batteries used for cars). Lithium batteries can be done combining lithium with many things, so I don't exactly know what you have on your hands.
Normally in chemistry labs you have some dedicated liquid to wash yourself when such an accident happens. In your case you have probably nothing better than water, and it's certainly too late anyway.
charcinders
"what is that?" - unknown. It depends on the type of battery.
As it's an AA size it's probably a lithium-iron type. The electrolyte in them contains propylene carbonate, dioxolane and dimethoxyethane. None of those is particularly dangerous but they could trigger a skin reaction. Wash with plenty of water and next time you mess with something be more careful, you know what curiosity did...
Zohey
Its the battery acid, its never a good idea to open a battery for that reason and if you get acid on you it should be washed off ASAP before it causes more harm. I watched as a truck battery exploded and splattered him, he washed it off his skin immediately but his clothes deteriorated and fell apart a few hours later.
I suggest rinsing your hand and if it gets worse consult your doctor
Hines
1
maps3333
battery acid. You never open a battery like that. Now you put the battery in a bag and take it to a recycle center or battery recycle bin. All dead batteries go into the battery recycle bin.