What kind of harm will the lithium battery cause when it is overcharged and discharged? The lithium battery is a rechargeable battery. The general lithium battery is fully charged with 4.2V and other voltages. Lithium battery charging methods include fast charge, slow charge, trickle charge, constant current charge, etc. However, be careful to prevent problems such as overcharging, overdischarging, and short circuit protection of the lithium battery.
If the lithium battery is overcharged, continuing to charge when the battery is full will cause a change in the structure of the positive electrode material, resulting in a loss of capacity, and the liberation of oxygen and the electrolyte will cause a violent chemical reaction. The worst result is an explosion. .
After the lithium battery discharges the internal stored power, after the voltage reaches a certain value, the discharge will continue to cause overdischarge, and the discharge cutoff voltage is usually determined according to the discharge current. 0.2C-2C discharge is generally set to 1.0V / support, 3C or above, such as 5C or 10C discharge is set to 0.8V / support, battery over discharge may have catastrophic consequences for the battery, especially high current over discharge, or Repeated overdischarge has a greater impact on the battery.
In general, 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 the charging is only partially restored, the capacity will be significantly attenuated. Lithium battery deep-filled deep, the battery loss will be greater, the ideal state of lithium battery work is shallow charge, so the battery life will be longer.
Why is there a gas generated when the lithium battery is overcharged or overdischarged?
Ordinary lithium-ion batteries generate a small amount of gas inside the battery during charging, which is generally absorbed during discharge. If the charging current is too large, the overcharging will increase the gas generation, and the internal pressure of the lithium battery will increase to cause swelling. A slight bulging of the battery is allowed, and avoiding overcharging is the key to reducing bulging.
In addition, the chemical properties of lithium are very active and easy to burn. When the lithium battery is charged and discharged, the inside of the battery continues to heat up. The gas generated during the activation process expands, and the internal pressure of the battery increases. When the pressure reaches a certain level, it will rupture, causing leakage. Liquid, fire, and even explosion, so it's absolutely important to ensure safety.
Lithium battery overcharge control method
In order to prevent overcharging of the lithium battery, it is necessary to control the charging end point. When the battery is full, some special information can be used to judge whether the charging reaches the end point. There are generally six ways to prevent the battery from being overcharged:
1. Peak voltage control: determine the end point of charging by detecting the peak voltage of the battery;
2.dT/dt control: determine the end point of charging by detecting the peak temperature change rate of the battery;
3.T control: When the battery is fully charged, the difference between temperature and ambient temperature will reach the maximum;
4.-V control: When the battery is fully charged to reach a peak voltage, the voltage will drop to a certain value;
5. Timing control: control the charging end point by setting a certain charging time, generally set the time required to charge 130% of the nominal capacity to control;
6. TCO control: Considering the safety and characteristics of lithium batteries, high temperature (except high temperature batteries) should be avoided, so charging should be stopped when the battery temperature rises by 60.
Lithium battery advantage
High energy density
High working voltage
No memory effect
Long cycle life, no pollution
Light weight, small self-discharge
Summary: Lithium battery overcharge, over-discharge will affect the battery life. Pay attention to the charging voltage and charging current of the lithium battery. Then select the appropriate charging chip to correctly charge the lithium battery to avoid shortening its life.