Comment The key to longevity! (from an EE) (Score 1) 142
The best way to preserve the longevity of any Lithium-Ion battery (Ternary and LFP, though LFP is way less sensitive) is to avoid time spent at very high or very low states of charge. If you only charge to ~75% daily, your battery will last longer than the phone will still be worth using! Same goes for laptops, they are especially bad, as they spend most of their life sitting at 100% SoC (State-of-Charge) and at high temperatures, which is even worse.
Most laptops now have a way to set the upper charge limit, but phones do not, though some claim to do it automatically. You can buy an external device, such as a "Chargie", or root/jailbreak your phone, but most manufacturers would rather your battery die early so they can sell you a new phone. Charging to 100% daily will get you marked degradation within even a year, and usability impacting within 2 years. If you only take it to 75% you'll probably not even have any observable loss of capacity after 2 years. Most devices now charge fast, so you can just take it to 100% only when needed, and don't let it sit at 100% long. (I only do it right before getting on a plane, etc)