Comment on lithium batteries vs nickel metal hydride.

Comment on lithium batteries.  Lithium batteries are good if you remember to keep them charged, though chemistries are improving so things might've changed or might change for the better.  Right now, if a lithium battery is left to itself without charging for a few years, the battery loses charge and inflates becoming nonfunctional.   Nickel Metal Hydride might occupy more space and probably weight more, and might be more expensive, but some nickel metal hydride products claim to maintain a charge for over 10 years, they also claim thousands of recharge cycles vs the usual hundreds for lithium.  

So hypothetically if you get products with 10+years of charge and thousands of recharge cycles, you can just store large quantities of such, and they should work with no trouble, hypothetically speaking.

All in all in terms of survival gear, it would seem Nickel Metal Hydride solutions like the eneloop brand seem better.   Though if you're near the beach, you have to keep them in some box, as my last eneloop battery terminals became oxidized while I was near the beach for a good portion of the year.  

There are charger powerbank devices that can charge the AA and AAA batteries and can also use the batteries to charge usb devices.  These battery power banks from various brands can be obtained at amazon with free shipping in many cases if you've prime

Costco sells the eneloop with non-powerbank(can charge batteries but can't use charger to charge usb devices from batteries) charger for a good price.