Why do lithium batteries for electric vehicles explode?

1. Overcharge causes too much lithium to be released, and the capacity of the negative electrode is insufficient. The lithium that appears during charging cannot be inserted into the interlayer structure of the negative electrode graphite, and metallic lithium will be formed on the surface of the negative electrode. Over time, 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 diaphragm 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 break, allowing oxygen to enter and react with the lithium atoms accumulated on the surface of the negative electrode. And then exploded. 2. Current limitation is also necessary when charging and discharging. When the current is too large, lithium ions will not have time to enter the interlayer structure and will also collect on the surface of the negative electrode 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. Therefore, in the lithium battery pack, in addition to the lithium battery core, there will be a protective board, which is what we often call BMS (BATTERYMANAGEMENTSYSTEM), the Chinese name is battery management system. It can monitor the voltage, current and temperature of the lithium battery, and intervene when needed based on the status of the lithium battery. Whether it is an electric car or an electric bicycle, lithium battery accidents are no longer a novelty. In the era of the old national standard, a small amount of lithium batteries have been used in the electric vehicle industry, and many safety accidents have occurred. The main reasons are the instability of lithium batteries, the immature PACK process, and the poor use of lithium batteries due to lack of knowledge. Habits and so on. With the rapid increase in the use of lithium batteries in the era of the new national standard, if some measures are not taken, the probability of accidents can be imagined. 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.