As a tangent, I may have purchased my last L91. No, I haven't stopped using them, as their lightweight and high capacity is unmatched so far.
My local recycle center accepts batteries, any kind, you can just drop 'em off in a bucket. I put on some gloves and started picking through them. Got a few laptop batteries that I intend to sort through and pull any good ones. Several NiMH, some of which are actually still very serviceable. But lots of lithium primaries, mostly AA, but a few AAA. Voltage of a brand new L91 is 1.8v. Several of my dumpster-dives are just that, 1.8v. I have no idea why someone tossed them. I've sorted them all by voltage and since these will be used in 1xAA applications, no worries about imbalanced voltage across multiple cells. I must have about $100 in lithium primaries in my storage closet now.
I just had a friend over and had an extra AA light that a company had sent me for review. I didn't care for the UI of the light all that much, so I really didn't want two of these lights around. So I gave it to him and popped in one of the salvaged L91's so he was good to go. If I had paid $2.00 for that cell, I wouldn't have felt quite so generous!