the lack of 3D will improve the battery life naturally, but the lower cost of the console doesnt suggest that they would put a better battery, rather they will use the same one as either the regular 3DS or the 3DS XL. for only 130 dollars i don't think you will get much in terms of battery life..but they might put the XL battery to improve sales.
According to charts I've seen the battery in the 2DS is only slightly better than the original 3DS (reported at 3.5-5.5 hours) --- Rikkka66: It's such a pain chasing after a burning medic while screaming "Come back! I need to blow you!" into the mic.