I find Lithium-Ion batteries absolutely fascinating. Gone are the days of Alkaline fuel cells that mainly leak and perform poorly.
What helped me understand lithium batteries is the fact that lithium crystals remain liquid under current and harden without current. That is why lithium batteries should always be fully charged – to keep the crystals fluid. An iPhone that is constantly connected to the power supply is therefore not a bad thing. But lithium batteries must also be handled carefully. The video "Everything You Need to Know About Exploding Batteries" from iFixit explains very well under what circumstances lithium batteries can explode.
Although I (household) try to keep lithium battery cells to a minimum in my environment, they are everywhere: two (three) iPhones, two (four) laptops, one (two) iPads, AirPods, Anker Soundbuds, two headsets, two mice, one NiteCore power-bank, three 18650 batteries, two 10440, two 14500 and various CR123s. Seriously, that's a lot of lithium! On the plus side we almost use zero AA/AAA batteries anymore.
The times where I only used CR123 for flashlights are over. Today it is primarily 18650 and 14500 which feed my ReyLight flashlights. My one-and-only SureFire – the single-cell Aviator – flashlight still uses CR123 batteries, which I deliberately keep as plan B.
(2,3000 lumens please)
I don't think my 18650 battery or my devices with lithium in my pocket can be punctured by a pen or discharged with a paper clip. However, I treat these things as if it could happen. Likewise, I do not charge batteries and devices overnight if I can avoid it. Last but not least, I/we use only the best cells, chargers, cables and everything USB-C.
For storing my lithium cells I rely on the Thyrm CellVault-5M:
(Individual storage options for 18650, 14500 and CR123 cells)