What is battery overcharge and overdischarge? How to prevent it?

Overcharge means that when the lithium ion battery is overcharged, the charging voltage exceeds the set voltage, for example, the battery rated voltage is 3.7V, and the full-charge voltage is 4.2±0.05V. That is, the highest voltage is 4.25V. If it exceeds 4.25V, it is called overcharge. What are the hazards of overcharge to the battery? During overcharge, the battery voltage rises rapidly with the increase in polarization, which will cause irreversible changes in the structure of the positive electrode active material and decomposition of the electrolyte, a large amount of gas will appear, a lot of heat will be released, and the battery temperature and internal pressure will increase sharply. The diaphragm melts or shrinks, causing the positive and negative materials to contact and short-circuit, and there are hidden dangers such as explosion and combustion. Over-discharge: Over-discharge refers to the continuous discharge when the voltage reaches the rated voltage. For example, the rated discharge voltage of a ternary lithium-ion battery is 3.2V, and it is over-discharged if it continues to discharge below 3.2V. What are the hazards of over-discharge to batteries? After the battery has discharged the internally stored power and the voltage reaches a certain value, continued discharge will cause overdischarge. Overdischarge of the battery may bring catastrophic consequences to the battery, especially high current overdischarge or repeated overdischarge. Bigger. Generally speaking, over-discharge will increase the internal pressure of the battery, destroy the reversibility of the positive and negative active materials, decompose the electrolyte, deposit lithium ions in the negative electrode, and increase the resistance. Even if it is charged, it can only partially recover, and the capacity will be obvious. attenuation. How to prevent the battery from being overcharged or over-discharged? One: Use the lithium-ion battery special protection board (BMS) to work with the battery. The protection board can protect the battery from overcharging or overdischarging. The smart version can also set the charging voltage and discharging voltage to better protect the battery. Two: Use the matching lithium-ion battery charger instead of fast charging. Three: When the battery voltage reaches the voltage set by the protection board, the protection board will cut off the power to protect the battery, but the lithium-ion battery will fall back and the voltage will rise, which will be a little higher than the voltage set by the protection board. It can no longer be used at this time. Repeated use will cause irreversible damage to the battery. The life span of lithium-ion batteries has been determined. First of all, there is an objective fact that cannot be changed, that is, the battery life of a mobile phone, which is similar to the lifespan of a person. If a person is tossed too hard, he may live a few years less, and if he has good habits, he can live a few more years. The same is true for lithium-ion batteries. If they are used properly, they can be used for a few more years, and the service life is very short. Just like human life, there will always be an end if there is no tossing, and the same is true for lithium-ion batteries. Over time, even if they are not used, they will slowly age. Moreover, it is still irreversible, so if the battery capacity of the mobile phone has been depleted, there is no way to restore it to the state of the new mobile phone. The working principle of lithium-ion batteries is very simple. Charging and discharging are actually chemical reactions inside the battery. Either way, they will experience the movement of ions from the negative electrode to the positive electrode or from the positive electrode to the negative electrode. The compounds that make up the positive and negative electrodes react with each other. After switching back and forth, the loss of the battery is actually a decrease in the activity of the ions. 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 article: What are the differences between lithium ion battery power lithium battery and energy storage technology battery?