It seems like a month does not go by, without hearing news reports about battery explosions in e-cigs, headphones, smartphones or other electronic gadgets. Granted that stories about explosions are considered newsworthy, but has the statistical rate of battery failures actually gone up in the last few years? Has the impact of battery failures increased and if so, why? And, I am of course talking about Lithium ion batteries, the go-to battery chemistry in rechargeable electronic devices owing to their high energy density. I am certain you do not want to be carrying around a brick for a smartphone.
In recent years the practice of buying spare e-cigarette batteries online has started to increase, with some users scouting for higher amp-hour/power batteries in order to get a better vaping experience. This is particularly true for mechanical mod e-cigs, which are highly customizable and do not use protection circuitry. The battery protection circuit is what keeps a lithium-ion battery within its operating window, and prevents it from overheating, overcharge and other potentially dangerous situations.
My cousin recently came to me with a battery problem. He got a drone for Christmas, and he had not opened it for a while. "Last Christmas, right?", I asked. Apparently, it was the Christmas before (i.e a year and a half of being in a box). "Uh-oh," I say. I almost knew what was coming. The drone obviously did not work, and I got to see a picture of a very bloated Lithium Ion pouch cell. Your Lithium-Ion battery does need some attention from you every few months in the form of a periodic recharge, or you will end up with a cell that looks like the image below. (My colleagues have brought me plenty of gadgets with the plastic case popped open from a bloated battery)