What harm will the lithium battery bring to the battery due to overcharge and over-discharge?
If a lithium battery is overcharged, continuing to charge when the battery is full will cause changes in the structure of the positive electrode material, resulting in a loss of capacity, and a violent chemical reaction will occur between the liberated oxygen and the electrolyte, and the worst result will naturally be an explosion.
After the lithium battery has discharged the internally stored power and the voltage reaches a certain value, the continued discharge will cause over-discharge, and the discharge cut-off voltage is usually determined according to the discharge current. 0.2C-2C discharge is generally set to 1.0V/branch, and above 3C, such as 5C or 10C discharge is set to 0.8V/branch. Over-discharge of the battery may bring catastrophic consequences to the battery, especially high current over-discharge, or Repeated over-discharge has a greater impact on the battery.
Generally speaking, over-discharge will increase the internal pressure of the lithium battery, and the reversibility of the positive and negative active materials will be destroyed. Even if it is charged, it can only be partially recovered, and the capacity will be significantly attenuated. If the lithium battery is deeply charged and discharged, the loss of the battery will be greater. The ideal state of the lithium battery is shallow charging and shallow discharge, in which case the battery life will be longer.