Reasons Why Lithium Battery Explode

Lithium battery explosions are caused by a combination of factors. Here are a few of the main reasons that can cause lithium batteries to explode:

1.Overcharging

Protection circuit malfunction or detection cabinet malfunction can result in charging voltage exceeding 5V, causing electrolyte decomposition and triggering a severe reaction within the battery. The internal pressure of the battery quickly rises, leading to battery explosion. When charging lithium batteries, it is crucial to set a voltage upper limit to ensure a balance between battery lifespan, capacity, and safety. The ideal charging voltage upper limit is 4.2V.

2.Over discharging

Over-discharging or discharging at high currents (above 3C) can lead to the dissolution of the copper foil on the negative electrode, depositing it onto the separator and causing a direct short circuit between the positive and negative electrodes, resulting in an explosion (although this is rare). When discharging lithium batteries, it is also important to have a voltage lower limit. When the cell voltage drops below 2.4V, some materials can start to degrade. Additionally, due to self-discharge, the voltage decreases the longer the battery is discharged. Therefore, it is recommended not to discharge until reaching 2.4V. During the discharge from 3.0V to 2.4V, only around 3% of the battery capacity is utilized. Hence, 3.0V is an ideal cutoff voltage.

3.Overcurrent

If the protection circuit or detection cabinet malfunctions, causing excessive charging current, it can prevent lithium ions from being properly embedded, resulting in the formation of metallic lithium on the electrode surface. This can penetrate the separator and lead to a direct short circuit between the positive and negative electrodes, causing an explosion (although this is rare). Besides voltage limitations, it is also necessary to impose current limitations during charging and discharging. When the current is too high, lithium ions are unable to enter the storage compartment and instead accumulate on the surface of the materials.

4.Vibration and drop

When the cell is violently vibrated or dropped, the internal electrode of the cell are dislocated, resulting in a serious short circuit and explosion (rarely happens).

5.Incorrect operation

(1).Ultrasonic welding of plastic shell

When ultrasonic welding of plastic shells, due to equipment reasons, the ultrasonic energy is transferred to the battery core. Excessive ultrasonic energy causes the internal separator of the battery to melt, causing the positive and negative electrodes to be directly short-circuited, causing an explosion.

(2).Spot welding

Excessive current during spot welding caused a serious internal short circuit and caused an explosion. In addition, during spot welding, the positive electrode connecting piece was directly connected to the negative electrode, causing the positive and negative electrodes to be directly short-circuited and exploded.

How to ensure the safety when using lithium battery

1. During use, do not bring the positive and negative electrodes of the lithium-ion battery into contact with metal objects. When placing it, keep it away from metal objects and places with high temperatures to avoid short circuiting the lithium-ion battery.
2.  When not in use for a long time, lithium-ion batteries should be stored in a low temperature, dry environment, away from heat sources and away from direct sunlight; it is generally believed that they should be charged to about 40% of the battery at a temperature of 10~30°C. Save it and recharge it every six months or so.
3. Before charging and discharging lithium batteries, it is recommended to check the voltage of each cell of the battery; the cell voltage within 1 month after leaving the factory is about 3.8v, the maximum limit voltage that the cell can withstand is 4.25V, and the minimum limit voltage is 2.75V. When the battery voltage is higher than 4.25V or lower than 2.75V, the charge and discharge performance and safety performance of the battery may be damaged, which may cause heat, leakage, and bloating.
4. Lithium-ion batteries are different from nickel-chromium and nickel-metal hydride batteries because they have a very bad aging characteristic, that is, part of their capacity will be permanently lost after being stored for a period of time even if it is not recycled. Lithium-ion batteries should be fully charged Re-storage can reduce capacity loss, and the aging speed is also different under different temperatures and different power states.
5. It is not advisable to overcharge or over-discharge during the charging process. We often like to charge the device for a while after it is fully charged, so that our device can withstand a longer period of time. Long-term overcharging and over-discharging will cause serious damage and destruction to the performance of lithium-ion batteries, and in severe cases may cause explosions and other extreme situations, so the lithium-ion battery should be fully charged.