FWIW, a quite interesting “new” lithium battery is on the market, now:
https://www.amazon.com/EBL-USB-Rechargeable-Lithium-Batteries/dp/B0828KRQZ3
Most interesting, to me, anyway, is the availability in an AA, 1.5 volt package.
I wonder if the internal battery is actually 3.7 volts, and then internal circuitry regulates the output down to 1.5 volts? If so, does that limit the output current to a lower value than a “simple” NiMH AA battery?
I also wonder what the (charged) shelf life is like. Panasonic has their latest “Eneloop” NiMH AA batteries up to an almost amazing (for NiMH) 10 years, with 70% of the charge remaining. (Not to mention a charge cycle life of 2100 cycles!)
Yes it is.