lithium 3400mah 3.7v 18650 battery

　　Effect of fast charging strategy selection on 18650 battery life

　　With the gradual increase in the popularity of electric vehicles, more and more electric vehicles have entered the daily life of ordinary consumers. The service life of power batteries is often one of the focuses that people worry about, which is also the cause of second-hand new energy. An important reason for the low value retention rate of automobiles, so the cycle life is also a very important assessment index for power batteries.

　　With the gradual increase in the popularity of electric vehicles, more and more electric vehicles have entered the daily life of ordinary consumers. The service life of power batteries is often one of the focuses that people worry about, which is also the cause of second-hand new energy. An important reason for the low value retention rate of automobiles, so the cycle life is also a very important assessment index for power batteries. Generally speaking, the cycle life of lithium-ion batteries and the choice of positive and negative electrode materials and electrolyte have the greatest impact on the cycle life, followed by the use strategy of lithium-ion batteries, such as charging and discharging systems, operating temperature, etc., will affect the cycle life of lithium-ion batteries have a noticeable impact. Peter Keil (first author, corresponding author) and Andreas Jossen of the Technical University of Munich, Germany, analyzed the impact of charging strategies on the cycle of different types of power 18650 batteries. First of all, let's analyze several common charging strategies 1. Constant current and constant voltage (CCCV) constant current and constant voltage charging is the most common and common charging method. Charging, when the set voltage is reached, the control voltage remains unchanged and the charging current is continuously reduced until the current reaches the set value or the time reaches the set value (as shown in Figure a below). The charging time of this charging strategy is mainly affected by the constant current charging current Icc, and the charging capacity is mainly affected by the charging cut-off voltage Vch and the constant voltage charging cut-off current Iend, and related studies have also shown that high charging cut-off voltage Vch and large A high charging current Icc will lead to a significant deterioration in the life of the Li-ion battery. 2. The multi-step constant current charging method (MSCC) no longer uses constant voltage charging in this charging strategy, but adopts a multi-step constant current charging strategy with decreasing charging current, for example, after using I1 constant current charging to the cut-off voltage , continue to use a smaller current I2 to charge to the cut-off voltage, and so on until the current decreases to the final cut-off current (as shown in Figure b below). 3. Pulse charging method (PC) This charging method can be found in some related literature reports. In the charging process of this charging strategy, a series of short-term adjustments to the charging current or even the charging direction (discharging) may be used. Time pulse structure, there are two common pulse charging strategies, one is to replace only the constant voltage charging part of CCCV charging with pulse charging (as shown in Figure c below), and the other is to replace the entire process with pulse charging (As shown in Figure d below). 4. Accelerated charging (BC) The so-called accelerated charging mode is to add a high-current CC or constant power charging process on the basis of the CCCV charging mode, so as to achieve the purpose of reducing the charging time (as shown in Figure e below). There are studies It shows that the accelerated charging mode can effectively improve the charging efficiency of the lithium-ion battery without significantly affecting the cycle life of the lithium-ion battery.