Are lithium-ion battery packs prone to explosion?
Lithium-ion battery explosions can be categorized into three types: external short circuit, internal short circuit, and overcharging. The highly reactive chemical properties of lithium metal impose stringent environmental requirements on its processing, storage, and use. However, with technological advancements and the selection of reputable products, lithium-ion battery explosions can be completely prevented.
Here's the crucial point: although the separator seems insignificant and has no performance-enhancing effect on the lithium-ion battery pack, it is actually the most vital component of a lithium-ion battery. This is because the separator acts as a protective barrier within the lithium-ion battery. During the charging and discharging process of a lithium-ion battery, the positive and negative electrodes must never come into contact; otherwise, a short circuit will occur, causing the battery to overheat abnormally. At best, this will lead to battery bulging; at worst, it can cause combustion or even an explosion.
Once the separator is broken, it lays a solid foundation for unfriendly contact between the positive and negative electrode materials. If you were to impulsively puncture a lithium-ion battery with a metal blade or scissors tip in the spirit of a scientific experiment, it would directly cause the positive and negative electrode materials to come into contact, resulting in a short circuit.
In theory, legitimate lithium-ion battery packs undergo puncture certification before leaving the factory. This involves puncturing the battery with a pressure needle of a certain diameter without causing it to catch fire or explode. Only after passing this test can the battery be mass-produced and shipped. However, each of these steps—short circuits caused by compression, collisions, punctures, or deformation; high temperatures caused by short circuits; and combustion triggered by high temperatures—is a low-probability event. Only when several low-probability events are met simultaneously can a serious deflagration accident occur.
In addition, lithium-ion battery packs are usually equipped with a BMS protection board, which can accurately control the state of each cell in the battery pack, directly solving the problem of overcharging and over-discharging from the root.
1. Overcharge explosion
If the protection circuit or the detection cabinet malfunctions, causing the charging voltage to exceed 5V, the electrolyte will decompose, resulting in a violent reaction inside the lithium-ion battery pack. The internal pressure of the battery will rise rapidly, and the battery will explode.
2. Overcurrent explosion
If the protection circuit or the detection cabinet malfunctions, the charging current may be too large, causing lithium ions to not have time to intercalate and instead form lithium metal on the electrode surface. This lithium metal can penetrate the separator, causing a direct short circuit between the positive and negative electrodes and resulting in an explosion (which is rare).
3. Explosion during ultrasonic welding of plastic casing
During ultrasonic welding of the plastic casing, due to equipment malfunctions, the ultrasonic energy was transferred to the battery cell. The high ultrasonic energy caused the internal separator of the lithium-ion battery pack to melt, resulting in a direct short circuit between the positive and negative electrodes and an explosion.
4. Explosion during spot welding
Excessive current during spot welding caused a severe internal short circuit, leading to an explosion. Additionally, the positive electrode connector was directly connected to the negative electrode during spot welding, causing a direct short circuit between the positive and negative electrodes, which resulted in an explosion.
5. Over-explosion explosion
Over-discharge or overcurrent discharge of a battery can cause the copper foil on the negative electrode to dissolve and deposit on the separator, resulting in a direct short circuit between the positive and negative electrodes and an explosion.
6. Explosion upon vibration and drop
When a battery cell is subjected to severe vibration or a drop, the internal electrode plates may become misaligned, causing a direct and serious short circuit and resulting in an explosion.
Can a lithium-ion battery explode if it short-circuits?
A lithium-ion battery short circuit occurs when the positive and negative terminals of the battery are directly connected by a wire, creating an abnormal circuit. This can lead to severe damage to the battery, causing combustion and potentially a fire, or the battery container may explode due to excessive pressure. Whether it's a lithium-ion battery short circuit or an electrical short circuit, the excessive heat generated during the short circuit reaches extremely high temperatures, enough to melt most metals before the circuit is broken. This can cause a fire or damage electrical appliances, threatening property and lives.
