Why do we need proteciton circuit board for li-ion battery?
Lithium-ion battery operates between 3.0V and 4.2V. Outside this range, the capacity, life, and safety of the battery will degrade. When below 2.4V, the metal plates of the battery will be eroded, which may cause higher impedance, lower capacity and short circuit. When over 4.3V, the cycle life and capacity will be hurt. More over, lithium crystal will grow, which may eventually cause internal short circuit and explosion.