How to guard against lithium battery explosion

When a lithium 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 short-circuiting due to direct contact between the positive and negative electrodes of the battery, a diaphragm paper with many pores is added to the battery to prevent short-circuits. 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 that they can use their own martial arts and guard against risks. Maintenance measures After the lithium battery cell is overcharged to a voltage higher than 4.2V, secondary use will begin. The higher the overcharge voltage, the higher the risk. When 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 storage cell often collapses, causing a permanent decrease in battery capacity. If you continue to charge, because 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 blasts before the short circuit occurs. This is because during the overcharging process, the electrolyte and other materials will crack and generate gas, causing the battery shell or pressure valve to swell and break, allowing oxygen to enter and react with the lithium atoms accumulated on the surface of the negative electrode. And then blasted. Therefore, when charging a lithium battery, the upper limit of the voltage must be set to take into account the battery's life, capacity, and safety. The most ideal charging voltage upper limit is 4.2V. There is also a lower voltage limit when discharging lithium batteries. When the cell voltage is lower than 2.4V, part of the data will begin to be damaged. 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 when the lithium battery is discharged 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 voltage constraints, current constraints are also necessary. When the current is too large, lithium ions will not have time to enter the storage cell and will concentrate on the surface of the data. After these lithium ions obtain electrons, lithium atoms will crystallize on the surface of the data. This is the same as overcharging, which will pose a risk. If the battery casing breaks, it will burst. Therefore, the maintenance of lithium 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 the lithium battery pack, in addition to the lithium battery core, there will be a maintenance board, this maintenance board is essential to provide these three maintenance. However, these three maintenance of the maintenance board are obviously not enough, and there are still frequent incidents of lithium battery explosions around the world. To ensure the safety of the battery system, it is necessary to more carefully decompose the cause of the battery explosion. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete it.