How great is the damage to the battery caused by overcharge and overdischarge?

The so-called overcharging, as the name implies, means overcharging, that is, the battery continues to be charged after it is fully charged. After being fully charged, continue to charge to a certain level. The gas generated by the decomposition of the electrolyte in the lithium-ion battery will cause the battery to swell and even smoke. In this way, the battery will not work properly. Just like a balloon, the balloon will burst sooner or later if it continues to be filled after being filled. Some customers, for the sake of the beauty of their products, or to meet the requirements of product mold design, often only purchase batteries and design their own protection boards, which is also easy to cause overcharging. On the one hand, because their battery professional standards are not high, the experimental equipment is backward, and the designed overcharge protection parameters are different; on the other hand, because the quality of the cells produced by different cell manufacturers is different, the lithium materials used are also different. They can't judge, always use the same process to design the overcharge protection parameters, so it is easy to make mistakes and cause overcharge. Of course, one or two overcharges will not do much damage to the battery, and the user experience is not deep, but as time goes by, the battery will change in quality due to the change in quantity and the battery will not be discharged until it can’t be charged or discharged. , The result can be imagined. The so-called over-discharge of lithium-ion battery charging and discharging test refers to the discharge of the battery after the battery has discharged the internally stored power. After the voltage drops to a certain value, the battery continues to discharge, resulting in over-discharge. The discharge cut-off voltage is usually determined according to the discharge current, that is, the critical voltage value for judging whether it is over-discharged. For 3.7V lithium-ion batteries, 0.2C-2C discharge is generally set to 3.0V, and discharges above 3C, such as 5C or For 10C discharge, set it to 2.4V. Over-discharge of the battery will often bring catastrophic consequences to the battery, especially large current over-discharge, or repeated over-discharge, which has a greater impact on the electrical performance of the battery. This is like a person who loses three to five hundred milliliters of blood at a time, which will not affect people's health. However, once the blood loss is too much, the person's normal body functions cannot be maintained. If it reaches a certain level, the person will die. For batteries, over-discharge will increase the internal pressure of the battery, and the reversibility of the positive and negative active materials will be destroyed. Even if it is remedied by charging, it is difficult to recover all of it. Naturally, the capacity is obviously attenuated to a certain extent, and the battery is dead. , There is no way to come back to life. 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: What is the cause of thermal runaway caused by power lithium ion battery