Safeguard

After the lithium battery core is charged to the voltage higher than 4.2V, side effects will begin. The higher the voltage, the higher the risk. After the lithium battery voltage is higher than 4.2V, the number of lithium atoms in the positive electrode material is less than half. At this time, the storage grid will often collapse, causing the battery to cause permanent capacity loss. If it continues to charge, since the storage grid of the negative electrode is already filled with lithium atoms, the subsequent lithium metal will be accumulated on the surface of the negative electrode material. These lithium atoms grow from the direction of the lithium ion from the surface of the negative electrode. These lithium metal crystals will pass through the diaphragm to make the positive and negative extremely short circuit. Sometimes the battery explodes before the short circuit. This is because in the overcoming process, the electrolyte and other materials will decompose to produce gas, so that the battery shell or pressure valve will bleed and rupture, allowing oxygen to enter the lithium atomic reaction to the negative surface, and then then, and then then explode.

Therefore, when the lithium battery is charged, the voltage limit must be set to take into account the life, capacity, and safety of the battery at the same time. The most ideal charging voltage limit is 4.2V. There must be a lower limit when the lithium battery is discharged. When the battery voltage is lower than 2.4V, some materials begin to be destroyed. And because the battery will discharge self -discharge, the lower the voltage will be lower, so it is best not to stop at 2.4V when discharging. During the period 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 cuttering voltage. During the charging and discharge, in addition to the limitation of voltage, the limitation of current is also necessary. When the current is too large, the lithium ion is too late to enter the storage grid and will gather on the surface of the material.

After these lithium ions are electrons, lithium atomic crystals will be generated on the surface of the material, which will cause danger like over -charged. In case the battery shell is broken, it will explode. Therefore, the protection of lithium -ion batteries must include at least: the upper limit of charging voltage, the lower limit of discharge voltage, and the upper limit of the current. In general, there will be a protective board in the lithium battery pack, except for the lithium battery core. This protective board mainly provides these three protection. However, the three protection of the protective board is obviously not enough, and the global lithium battery explosion is still frequent. To ensure the safety of the battery system, the cause of the battery explosion must be more carefully analyzed.