Is it okay to use pulse charging for lithium ion battery cells 18650?

　　lithium ion battery cells 18650 have been widely used in daily life, but they still have shortcomings such as time-consuming charging, large power loss, and serious polarization. In order to achieve high-capacity, efficient and fast charging of lithium ion battery cells 18650, multiple studies have found that pulse fast charging can cause polarization reactions. At the same time, this charging method can not only increase the service life of the battery, but also greatly increase the charging speed and increase the charging capacity.

　　The standard charging method for lithium ion battery cells 18650 is CCCV, with constant current in the early stage and constant voltage in the later stage. Constant current charging is slower than pulse speed. Generally, common chargers are CCCV method. Nokia mobile phone and cradle charger and 1879 chip are all pulse method, and the speed is faster.

　　But there is no difference between the two. They are just different in terms of scope of application and charging mechanism. CCCV is the standard method, while pulse is a newer charging method. When charging with CCCV, you don’t need to pay too much attention to the selection of battery capacity. The rate is guaranteed to be within 1C. That's fine, but because the pulse charging current fluctuates, the high current when charging a small battery or a battery with reduced capacity may exceed 1C, or even more, causing the battery to heat up.

　　Pulse charging is to remove polarization effects; reduce charging voltage/suppress battery heating. This method is effective for thin plate structures, but not for thick plate batteries. The plates of power batteries are relatively thick, and pulse charging will increase the number of cycles of effective substances on the surface; while the reaction of substances in the inner layer is still very slow, so the advantage of using pulse mode for power batteries is not obvious. The electrolyte is circulated and pumped in the battery. is an effective solution.

　　The pulse charging method is a fast charging method that can effectively polarize the battery and reduce the charging time. Its principle is: after every period of forward charging pulse, a period of charging stop time and discharge pulse are added. There are two forms of pulse charging: positive charging. Pulse charging mode and positive and negative pulse charging mode.

　　When the battery is charged to the cut-off voltage, the positive and negative pulse charging methods can weaken the polarization phenomenon of the battery and increase the actual charging capacity of the battery; as the charging rate increases, compared with the constant current charging method, the actual positive and negative pulse charging methods More power is charged; the pulse cycle width of positive and negative pulse charging is reduced, and the actual charging power of positive and negative pulse charging increases.

　　The charging method of the battery is directly related to the cycle life and charging efficiency of the battery. For large-capacity batteries, we usually want the charging time to be as short as possible, the efficiency to be as high as possible, and the damage to the battery to be as small as possible. To reduce the charging time, the charging current must be increased, but the battery's acceptable continuous high charging current is limited, and the traditional charging method cannot significantly increase the charging current.

　　It has been confirmed that pulse charging can improve the charging efficiency of the battery while ensuring the charging efficiency. However, there is a lack of experimental basis for the charging effect of large-capacity lithium-ion batteries, especially for high-current charging (current above 1C, C is the rated capacity of the battery). Battery characteristics under conditions.

　　In short, under the condition of large charging current, the pulse charging method can effectively reduce the polarization phenomenon of lithium-ion batteries, so that they can be charged quickly and the damage to the battery can be greatly reduced. By rationally selecting pulse charging parameters, the pulse charging effect can be optimized.

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