How to do the battery drum shell

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. When the voltage of the lithium-ion battery cell is higher than 4.2V, the number of remaining lithium-ion atoms in the positive electrode material is less than half. At this time, the storage cell often collapses, causing the battery capacity to drop. If you continue to charge, since the storage cell of the negative electrode has been filled with lithium ion atoms, the subsequent lithium ion metal will accumulate on the surface of the negative electrode material. These lithium ion atoms will grow dendrites from the surface of the negative electrode to and from the lithium. These lithium ion 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, causing the battery shell or pressure valve to swell and rupture, allowing oxygen to enter and react with the lithium ion 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 life, capacity, and safety can be taken into account at the same time. The ideal upper limit of the charging voltage is 4.2V. There is also a lower voltage limit when discharging lithium-ion 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 better 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 will not have time to enter the cell and will accumulate on the surface of the material. After these lithium gain electrons, lithium ion 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 the 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. To ensure the safety of the battery system, a more careful analysis of the cause of the battery explosion should be carried out. Disclaimer: Some pictures and content of the articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous post: How does the memory effect of the battery affect the performance of the battery?