Introduction to the cause of lithium battery fire
Lithium batteries and lithium-ion batteries are a great technology that will surely bring huge changes and contributions to the storage and supply of global electric energy. So, what is the cause of the fire of the lithium battery? Let me introduce it below!
What are the causes of fire in lithium batteries?
The essence of causing a fire in a lithium battery is that the heat in the battery fails to be released in accordance with the design intent, causing internal and external combustion materials to ignite after ignition. The main causes are external short circuit, external high temperature and internal short circuit.
1. Internal short circuit
Due to the abuse of the battery, such as branch crystals caused by overcharge and overdischarge, impurities and dust in the battery production process, it will deteriorate to pierce the diaphragm and produce micro-short circuits. The release of electrical energy causes temperature rise, and material chemistry caused by temperature rise The reaction expands the short-circuit path and forms a larger short-circuit current. This mutually accumulating and mutually reinforcing destruction leads to thermal runaway.
2. External short circuit
Take electric cars as an example. The probability of danger in actual vehicle operation is very low. One is that the vehicle system is equipped with fuses and a battery management system BMS, and the other is that the battery can withstand a short-term high current impact. In extreme cases, the short-circuit point crosses the vehicle fuse, and the BMS fails. A long-term external short-circuit will generally cause the weak points in the circuit to burn out, and rarely cause thermal runaway events in the battery. Now, more PACK companies have adopted the method of adding fuses in the loop, which can more effectively avoid the harm caused by external short circuits.
3. High temperature outside
Due to the structural characteristics of lithium batteries, SEI membranes, electrolytes, ECs, etc. will undergo decomposition reactions at high temperatures. The decomposition products of the electrolytes will also react with the positive and negative electrodes, and the cell membrane will melt and decompose. Various reactions lead to a large amount of heat generation. . The melting of the diaphragm causes an internal short circuit, and the release of electrical energy increases the heat production. This cumulative and mutually reinforcing destructive effect will cause the explosion-proof membrane of the battery cell to rupture, the electrolyte will spray out, and the combustion will start.
We know the cause of the fire of lithium batteries, and know that lithium battery fires are extremely difficult to control. Therefore, once you find signs of smoke or fire in the use of electric vehicles, you must escape as soon as possible.
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