Originally posted by kravenar
Different flavours NiMH / NiCad etc and other advances have made improvements on battery life, battery memory etc.. but you still need a certain amount of material to react.... I think that is where the stumbling block has been in making them any smaller.
Side point: Most laptop batteries (others too but harder to generalize) are Li-ion. Lithium batteries are _less_ efficient (in terms of power output per size) than several other chemistries, but the advantage is weight. NiMH batteries are available for a number of models of laptop, so if you really need that bit more battery life, it might be a good option.