Might want to check out Mooltipass. I got mine from tindie and they’re worth a look IMO.

I’ve used imrbatteries.com a handful of times in the past, no issues so far and my oldest set of batteries are several years old at this point.

Lightning has a peak power of 1TW for 30 microseconds according to Wikipedia, corresponding to an energy content of about 8000 Watt-hours. That is enough to run a 100 watt conventional light bulb for 80 hours, so not actually much energy. You would need to capture about half a million lightning strikes a second if you wanted to power the world that way, for example.