Lithium battery maintenance analysis

After the lithium battery cell is overcharged to a voltage higher than 4.2V, side effects will begin to occur. 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 remaining lithium atoms in the positive electrode material is less than half. At this moment, 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 to the direction of the lithium ions. These lithium metal crystals will pass through the barrier paper and short-circuit the positive and negative electrodes. Sometimes the battery explodes before the short circuit occurs. This is because during the overcharge 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 exploded. Therefore, when charging a lithium 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 data 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 when the lithium battery is discharged from 3.0V to 2.4V, the released energy 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 be concentrated on the data surface. After these lithium ions obtain electrons, lithium atoms will crystallize on the surface of the data, which is the same as overcharging and can cause danger. If the battery casing is broken, it will explode. 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. In general, in the lithium battery pack, in addition to the lithium battery core, there will be a maintenance board, this maintenance board is mainly to provide these three maintenance. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous post: The important reason for the short circuit of lithium iron phosphate battery