Fully charging full discharge cycles, but most of all deep charge cycles are the best things available when you want to kill a Li based rechargeable battery.
Heat does a great job too, in this regard.

I am trying to disconnect my phone when it's 85% full and recharge it when it's around 50%.

My 3 year Vaio has a built-in function to stop charging when it's 50% charged for maximum protection and 80% for a good balance of charge and battery life. Unfortunately, this is a hardware function and can't be easily implemented afaik.