Most phone batteries sold in the United States are lithium-ion, and due to the chemical properties of the cells, maintaining a fully charged state (near 100%) for a long time increases internal chemical stress, which shortens their lifespan.

First, voltage stress
As the charge level increases (voltage rises), the chemical instability between the anode and cathode increases. If the voltage is maintained near the peak (about 4.2V/cell), unnecessary compounds accumulate on the electrode surface, gradually reducing the charge and discharge capacity.

Second, reduced cycle life
There is a concept of battery life cycles measured by manufacturers (one full charge after complete discharge), but in reality, partial charge and discharge lasts longer. For example, using only the 20% to 80% range and recharging causes less battery damage than a full cycle from 0% to 100%.

Third, capacity degradation during long-term storage
If left in a fully charged state for several days or weeks, 'calendar aging' accelerates. This means that even when not in use, internal chemical reactions occur, naturally lowering the capacity.

How to use it for a long time?

-If you can limit the charging upper limit to 80-90% in the settings menu or manufacturer app, please do so. Charging from 20% to 80% is much better for battery lifespan than daily full charges from 0% to 100%.

-Try to reduce charging after the battery drops to 0%. Repeated complete discharges increase internal stress on the cells.

-Excessive heat during charging or use quickly depletes battery life. It's best to keep it in a well-ventilated area and avoid running heavy apps while charging.

-When not using the device for an extended period, store it at about half charge to minimize chemical reactions and suppress capacity degradation.

Ultimately, to use the battery for a long time, it is important to avoid both 'high voltage (100%)' and 'complete discharge (0%)', and to develop a habit of frequently charging and using it in the middle range.

Even small changes in habits can significantly increase the usable cycles, so give it a try!