What are the explosion-proof technologies for lithium-ion batteries

When a lithium-ion battery is charged, the lithium atoms in the positive electrode lose electrons and are oxidized to lithium ions. Lithium ions swim to the negative electrode through the electrolyte, enter the storage cell of the negative electrode, and obtain an electron, which is reduced to lithium atoms. When discharging, the whole procedure is reversed. In order to prevent the battery's positive and negative electrodes from directly touching and short-circuiting, a diaphragm paper with many pores is added to the battery to prevent short-circuiting. A good diaphragm paper can also automatically close the pores when the battery temperature is too high, so that lithium ions cannot pass through, so as to waste martial arts and prevent danger. Protective measures After the lithium-ion battery cell is overcharged to a voltage higher than 4.2V, side uses will begin to appear. The higher the overcharge voltage, the higher the risk. After the voltage of the lithium battery cell is higher than 4.2V, the number of lithium atoms remaining in the positive electrode material is less than half. At this time, the cell often collapses, causing a permanent decrease in battery capacity. If you continue to charge, since the storage cell of the negative electrode has been filled with lithium atoms, subsequent lithium metal will accumulate on the surface of the negative electrode material. These lithium atoms will grow dendrites from the surface of the negative electrode toward the direction of the lithium ions. These lithium metal crystals will pass through the separator paper and short-circuit the positive and negative electrodes. Sometimes the battery explodes before the short circuit occurs. This is because during the overcharging process, the electrolyte and other materials will crack and produce gas, which makes the battery shell or pressure valve swell and rupture, allowing oxygen to enter and react with the lithium atoms accumulated on the surface of the negative electrode. And then exploded. Therefore, when charging a lithium-ion battery, the upper limit of the voltage must be set so that the battery's life, capacity, and safety can be taken into account at the same time. The most ideal upper limit of the charging voltage is 4.2V. There is also a lower voltage limit when discharging lithium batteries. When the cell voltage is lower than 2.4V, some materials will begin to be destroyed. And because the battery will self-discharge, the longer it is left, the lower the voltage will be. Therefore, it is best not to stop when the battery is discharged to 2.4V. During the period of lithium ion battery discharge from 3.0V to 2.4V, the energy released only accounts for about 3% of the battery capacity. Therefore, 3.0V is an ideal discharge cut-off voltage. When charging and discharging, in addition to the voltage limit, the current limit is also necessary. When the current is too large, lithium ions will not have time to enter the storage cell and will gather on the surface of the material. After these lithium ions obtain electrons, lithium atoms will crystallize on the surface of the material, which is the same as overcharging and can cause danger. If the battery casing ruptures, it will explode. Therefore, the protection of lithium-ion batteries must include at least three items: the upper limit of the charging voltage, the lower limit of the discharge voltage, and the upper limit of the current. Generally, in a lithium-ion battery pack, in addition to the lithium-ion battery core, there will be a protective board. This protective board is important to provide these three protections. However, these three protections of the protection board are obviously not enough, and explosions of lithium-ion batteries are still frequent worldwide. To ensure the safety of the battery system, the cause of the battery explosion must be analyzed more carefully. Disclaimer: Some pictures and content of articles published on this site are from the Internet, please contact to delete if there is any infringement. Previous: Introduction to the performance advantages of capacitive lithium-ion batteries