candlelight, just as info, IMR (lithium manganese oxide, or LiMn) and the older cells you refer to, which are ICR , or more commonly called "LiCo" (lithium cobalt oxide) cells, are both "Li-Ion" cells. There is a third type of "Li-Ion" cell referred to here on the forums also, IFR, or more commonly called "LiFe", or LiFePO4 (lithium iron phosphate). These are all "Li-Ion" chemistry cells.
A fourth common "Li-Ion" chemistry that is used widely in the R/C world and some consumer electronics, such as cell phones and small PDA's etc, but not much in flashlights, is "LiPo", or lithium polymer, which is a form of "LiCo" chemistry that utilizes an electrolyte that is in a "polymer" form, rather than a liquid. There are also several other "Li-Ion" chemistries, as well.
LuxLuthor did a writeup a while back that explained some of the different characteristics of the various chemistries of Li-Ion cells we use here. You may want to
give it a look. Also,
Battery University is a commonly referred source of information about many types of battery chemistries, and their general characteristics.
Dave