Detailed knowledge about lithium-ion battery charging

Generally, the battery voltage of a mobile phone is written as 3.7V, but the voltage of a general charger is written as 5V, but it will not affect the use, because the mobile phone has a charging management chip responsible for step-down and constant current charging. No. 5 cylindrical lithium-ion battery, that is, a 14500 battery. It uses the technology of the lithium-ion battery voltage regulator to adjust the voltage of the battery to a voltage of 3.0V suitable for use by small appliances. Regarding the activation of newly purchased lithium-ion batteries, many claims are: the charging time must be more than 12 hours, repeated three times in order to activate the battery. This statement that the first three charges must be charged for more than 12 hours is obviously a continuation of the statement that nickel batteries (such as nickel-cadmium and nickel-metal hydride). So this statement can be said to be misinformation at the beginning. The charge and discharge characteristics of lithium-ion batteries and nickel batteries are very different, and it can be very clear to tell you that all serious official technical documents emphasize that overcharge and overdischarge will cause lithium-ion batteries, especially liquid lithium-ion batteries. Huge damage. Therefore, it is best to charge according to the standard time and standard method, especially not to charge more than 12 hours. So does the battery need to be activated? The answer is yes, to activate! However, this process is completed by the manufacturer, has nothing to do with the user, and the user has no ability to complete it. The real activation process of lithium-ion battery is as follows: the lithium-ion battery shell is filled with electrolyte-sealed-formed, which is constant voltage charging and then discharging. After several cycles, the electrode is fully immersed in the electrolyte and fully activated until the capacity is reached. Until the requirements are met, this is the activation process-capacity division, which means that the lithium-ion battery is already activated by the user after leaving the factory. In addition, the activation process of some of the batteries requires the battery to be in an open state, and then seal it after activation. Unless you have battery cell production equipment, how to complete it? But why is it written in the manuals of some products that users are advised to fully charge and discharge the mobile phone for the first three uses? Isn't this activation? In fact, the fact is that it will take a period of time, one month or several months, after the battery leaves the factory, is sold, and then reaches the user's hands. As a result, the electrode material of the battery will be passivated, and the capacity is lower than normal at this time. Value, the use time is also shortened. But lithium-ion batteries are easy to activate, as long as 35 normal charge and discharge cycles can activate the battery and restore normal capacity. Due to the characteristics of the lithium-ion battery itself, it is determined that it has almost no memory effect. Therefore, users do not need special methods and equipment during the activation process of new lithium-ion batteries. Long charge Deep charge Long charge may lead to overcharge. Li-ion batteries or chargers will automatically stop charging after the battery is fully charged, and there is no such thing as a trickle charge that lasts for more than 10 hours as a nickel charger. In other words, if your lithium-ion battery is fully charged, it is also white charged on the charger. And none of us can guarantee that the characteristics of the battery's charging and discharging protection circuit will never change and the quality will be foolproof, so your battery will be on the verge of danger for a long time. This is another reason why we oppose long charging. On some machines, after charging for a certain period of time, if the charger is not removed, the system will not stop charging at this time, but will also start a discharge-charge cycle. Perhaps the manufacturer of this approach has its own purpose, but it is clearly detrimental to the life of the battery. At the same time, long-term charging takes a long time and is often carried out at night. According to the situation of my country's power grid, the voltage at night in many places is relatively high and fluctuates greatly. As mentioned earlier, lithium-ion batteries are very delicate, and their ability to withstand fluctuations in charging and discharging is much worse than that of nickel batteries, so this brings additional dangers. In fact, shallow charging and shallow charging are more beneficial for lithium batteries. Only when the product's power module is calibrated for lithium batteries, it is necessary to deep discharge and deep charge. Therefore, products powered by lithium batteries do not need to be constrained by the process. Everything is convenient and can be charged at any time. The rated voltage of overcharged and overdischarged lithium-ion batteries is generally 3.7V due to material changes, and 3.2V for lithium iron phosphate (hereinafter referred to as ferrophosphorus) positive electrodes. The international standard for the termination charging voltage when fully charged is 4.2V and 3.6V for ferrophosphorus. The termination discharge voltage of lithium-ion batteries is 2.75V～3.0V (Domestic battery manufacturers give the operating voltage range or the termination discharge voltage, each parameter is slightly different, generally 3.0～2.75V, and phosphorus iron is 2.5V.). Continued discharge below 2.5V (ferro-phosphorus 2.0V) is called over-discharge (the international standard is 3.2v minimum and ferro-phosphorus 2.8v). Over-discharge or self-discharge reaction at low voltage will cause the decomposition and destruction of lithium ion active materials. It must be restored. Any form of overcharging of lithium-ion batteries will cause serious damage to battery performance and even explosion. Lithium-ion batteries must be prevented from overcharging during the charging process. 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: How to store lithium-ion battery packs correctly