I've pretty much moved to using only Eveready Lithium AA and AAA batteries for lights and devices that need to work during longer term storage, such as safety kits, in cars, in barns, tools such as laser measures, ... These also do very well in cold weather, and are noticeably lighter weight, if that matters.

My charging banks seem to store surprisingly well. I've not tracked how long they last though. Longer than my rechargeable nickel metal hydride AA's.

Recently I bought my first pontoon boat (a retirement requirement), and I noticed the marine shop using a small lithium battery booster to jump start the outboard. I bought the Noco Boost Plus battery booster linked below and was very pleased to see that it also has a USB power port. I had a more typical 12V battery jumper pack, but the thing is heavy and awkward to use hanging off the rear of the boat. The lithium battery booster is small, lightweight, and has enough power to jump my pickup's V8.

Right now I'm testing the shelf life. Every few days I turn it on to check the charge meter. I'm about 3 weeks in, and it still has a full charge. Oh, and it can be left plugged in - no harm. I like that.

https://no.co/gb40