Because accidents involving lithium battery explosions and fires that cause injuries and fatalities occur frequently, today we will explain the causes of lithium battery explosions.
With the widespread use of lithium batteries, many electric vehicles on the market now use lithium batteries. This has led to frequent accidents involving lithium battery explosions and fires that result in injuries and fatalities. What exactly causes this? Today, I will give you a detailed explanation.
I. Insufficient negative electrode capacity of lithium battery
When the capacity of the negative electrode portion of the positive electrode of a lithium battery is insufficient, the lithium atoms generated during charging cannot insert into the interlayer structure of the graphite in the negative electrode and will precipitate on the surface of the negative electrode, forming crystals.
Long-term crystal formation in lithium batteries can lead to short circuits. This causes the cell to discharge rapidly, generating a large amount of heat that can burn out the separator. High temperatures can also cause the electrolyte to decompose into gas, and when the pressure becomes too high, the cell can explode.
2. Excessive moisture content
During charging, moisture can react with lithium to form lithium oxide, causing a loss of battery cell capacity and making the cell prone to overcharging and gas generation. Moisture has a low decomposition voltage, making it easy to decompose and generate gas during charging. When this series of generated gases increases the internal pressure of the battery cell, the cell will explode when the outer casing cannot withstand the pressure.
III. Internal Short Circuit
An internal short circuit in the battery cell causes a large current discharge, generating a lot of heat, which burns the diaphragm and causes an even larger short circuit. This causes the electrolyte to decompose into gas, and if the internal pressure becomes too high, the battery cell will explode.
IV. Overcharging of lithium batteries
When a battery cell is overcharged, excessive lithium release from the positive electrode can alter its structure. Excessive lithium release can also prevent it from inserting into the negative electrode, leading to lithium deposition on the negative electrode surface. Furthermore, when the voltage reaches 4.5V or higher, the electrolyte decomposes, producing a large amount of gas. All of these factors can potentially cause an explosion.
V. External Short Circuit
An external short circuit may be caused by incorrect connection of the positive and negative terminals. Due to the external short circuit, the battery discharge current is very large, which will cause the cell to heat up. The high temperature will cause the diaphragm inside the cell to shrink or completely fail, resulting in an internal short circuit and thus an explosion.
