Will high-current fast charging damage the battery?

　　First of all, we must understand the charging and discharging principle of lithium-ion batteries. The battery has two poles: the positive electrode is a lithium compound, and the negative electrode is graphite. Both charging and discharging are the mutual conversion of electrical energy and chemical energy.

　　Fast charging is a relatively general concept, and it has three different implementation forms:

　　(1) The voltage remains unchanged, and the current is increased;

　　(2) The current remains unchanged, and the voltage is increased;

　　(3) Both voltage and current increase.

　　But to truly realize fast charging, it is not only enough to increase the voltage and current. Fast charging technology requires a complete set of customized circuits, batteries, interfaces, data cables, and supporting fast charging adapters. At the same time, a set of intelligent power management system is required to provide safe and intelligent charging protection.

　　At present, fast charging technology is relatively mature. Because the power management module is included in the plan, the highest voltage, current, temperature and other conditions that the battery can withstand are preset, and it also includes temperature protection, short-circuit protection, over-discharge protection, over-current protection, over-voltage protection, etc. technology.

　　In principle, the damage of the battery basically comes from two aspects:

　　On the one hand, when the battery is charged and discharged, the cathode and anode of the battery will shrink and expand with the release and absorption of ions. Long-term fast charging will destroy the chemical substances on the battery and shorten the battery life.

　　On the other hand, during fast charging, due to the relatively large current, the thermal effect will be aggravated, causing the battery to generate high temperatures. High temperature is a major factor in the capacity degradation of lithium batteries.

　　One of the advantages of lithium batteries is that they do not have the memory effect of lead-acid batteries and can be charged at any time. Here, we need to understand a concept, what is battery cycle life?

　　One cycle means the process of using all the power of the battery from full to empty, and then from empty to full. This is not the same as charging once. A lithium battery used only half of its power on the first day, and then it was fully charged. If the situation persists the next day, that is, use half of the charge and charge it twice in total. This can only be counted as one charging cycle, not two. Therefore, it may usually take several times of charging to complete a cycle.

　　Generally speaking, the cycle life of a ternary lithium battery is about 500 weeks, and the cycle life of lithium iron phosphate is as high as 4000 weeks. It is worth noting here that the cycle life is reached, not that the battery can no longer be used. The precise definition is that when the cycle life reaches the number set by the manufacturer, at least 80% of the battery capacity remains.

　　Therefore, we can also understand it this way: the life of a lithium battery is related to the total charge capacity of the battery, and has nothing to do with the number of recharges. Deep discharge and deep charge and shallow discharge and shallow charge have little difference in the impact on the life of the lithium battery.

　　In fact, shallow charging is more beneficial for lithium batteries. 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 without worrying about affecting the lifespan.

　　Lithium-ion battery (LIB) has become the main energy storage solution in modern social life. Among them, lithium iron phosphate batteries are a perfect replacement for lead-acid batteries, and they are the first choice for grid-connected peak shaving, off-grid energy storage, photovoltaic energy storage, UPS, data center and other industries.