I got tired of replacing teh alkaline batteries my LED flashlights were eating so started using NiCd. Then discovered they are only 1.3 volts and don't work well and didn't last long for powering LED flashlights.
I found there are 1.6 volt NiZn batteries and am trying them. Spec wise it looks like a winner, lots of power, much better discharge curve. Cost is a little higher (ebay direct from china) but no worse then NiCds were when they became popular. Now I have a whole bunch of AAA NiCds I have no use for....