Excessive charging and discharging of lithium ion batteries will cause permanent damage to the positive and negative electrodes. Overdischarge causes the negative carbon sheet structure to collapse, and the collapse will cause lithium ions to be unable to be inserted during charging; excessive charging causes too much lithium ions to be inserted into the negative electrode carbon structure, causing some of the lithium ions to be released no longer.
The charging amount is equal to the charging current multiplied by the charging time. Under a certain charging control voltage, the larger the charging current (the faster the charging speed), the smaller the charging capacity. Excessive battery charging speed and improper termination voltage control point will also cause insufficient battery capacity. In fact, some of the electrode active materials of the battery stop charging without sufficient response. This phenomenon of insufficient charging is exacerbated as the number of cycles increases.
Discharge
For the first charge and discharge, if the time can be longer (generally 3 to 4 hours is enough), the electrode can be made to reach the highest oxidation state (full charge) as much as possible. Voltage, or until automatic shutdown, this can activate the battery capacity.
However, in the ordinary use of lithium-ion batteries, this operation is not necessary, and it can be charged at any time as needed. When charging, it is not necessary to fully charge or discharge first. The operation like the first charge and discharge only needs to be performed once or twice every 3 to 4 months.