The reason behind the loss of capacity that occurs due to the emergence of stress. Similar is the case in humans, when the battery is too often used and charged, appears in the form of stress damage to the electrode. The part is electricity storage.
In addition, each charging also convicted of killing a small part electrode. Now, after hundreds of charging, the number of electrodes that die will increase to reduce overall battery capacity.
Lithium-ion battery itself is known to have a limit of charging up to 1500 times before finally being very wasteful. Therefore, you can start counting the number of times you recharge smartphones and set a schedule for battery replacement.
Smartphone battery that has passed its charging limit will be easily damaged or leaking. It is certainly dangerous for your smartphone.