FYI, I just got back form a trip and got hassled about batteries. I had the document Jack refers to or something very similar and pulled it out and was told by the gate agent that this was a homeland security issue and not an FAA issue. I disagreed as politely as possible and eventually prevailed, but almost lost some expensive batteries.
Also, be aware that although FAA rules prohibit lithium batteries in checked bags, Mexican airport security will seize any batteries they find in carry-on and will tell you they should have been in checked bags. They will also take not just lithium, but eneloops and energizers too. I speak from experience. I now have several "devices" I take with me to Mexico, with batteries installed, to get through Mexican airport security on the way back (primarily cheap flashlights that I do not use, that will hold AA, AAA, 18650 and similar batteries. I also leave such batteries installed in working lights and other devices when I go through security. Camera batteries are tougher challenge but if left in the charger they will often be ignored.