Analyze the charge-discharge cycle performance of lithium-ion batteries at room temperature

The charge-discharge cycle performance of lithium-ion batteries at room temperature. At room temperature, after a time-based charge and discharge of lithium-ion batteries, how does it perform during and after this process? This is a lithium-ion battery related technology The direction of improvement requires the application of certain test parameters to explain, because the popularity of new energy vehicles in our country is accelerating. Choosing the test data collection of large-capacity lithium-ion batteries will help understand the performance and characteristics of power lithium-ion batteries. Through the test of lithium-ion batteries, the following general conclusions can be drawn: According to the constant current and constant voltage charging stages, the ratio of the constant current charging capacity to the charging capacity decreases with the increase of the number of cycles; 3.7v~4.2v The discharge capacity of the discharge platform accounts for more than 90% of the total discharge capacity, and the charge and discharge efficiency is not affected by the number of cycles. The following is a detailed description. Before describing the data, it is necessary to explain the test environment: select BYD 80Ah lithium cobalt oxide battery for charging and discharging test at room temperature (10℃~250℃). Charging and discharging system design: charging is constant current and constant voltage. First, charge to 4.2v at a constant current of 1C or 80A. 2. After 10 minutes, use a constant current of 80A to reach 2.75v; 3. After continuous discharge for 10 minutes, perform a new charge and discharge cycle, repeat 500 times. In this process, relevant data should be collected to form the corresponding chart: constant current/constant voltage charging characteristic curve; 2.2. The relationship between the ratio of constant current charging capacity to the total charging capacity and the number of cycles; 3. Discharge curve; 4. Charge and discharge efficiency curve. It can be seen from the above figure: 1. Starting from the constant current charging stage, the charging platform of the lithium-ion battery is 3.8v~4.1v, and the charging capacity in this stage accounts for more than 80% of the total charging capacity. With the increase of the number of cycles, the voltage rise speed increases, the charging time shortens, and the charging capacity gradually decreases. 2. The percentage of constant current charging capacity is the total charging capacity. As the number of cycles is added, the percentage of constant current charging capacity decreases slightly in the total charging capacity, and the percentage of constant voltage charging capacity increases slightly in the total charging capacity. This shows that with the increase in the number of charging and discharging cycles of lithium-ion batteries, the smaller the current, the better the charging effect. 3.According to the discharge curve and discharge platform (the discharge curve is stable in a certain voltage range, close to a straight line, rather than the distance between the previous rise and fall slope lines) with the increase in the number of cycles, and the release of 4.2v~3.7 The power discharge platform accounts for 90% of the total power. 4. Charging and discharging efficiency: the percentage of the discharged electricity to the charged electricity. Indicates the discharge capacity of the battery. From the charging and discharging efficiency curve, the value remains basically unchanged, reaching more than 99%. We understand that the capacity of lithium-ion batteries decreases with the increase in the number of charge and discharge cycles, which can be obtained from the above data. The specific performance is: the discharge platform is reduced, the charging time of the lithium-ion battery is reduced, and the constant current charging ratio is reduced. The final performance is that the rechargeable power decreases as the number of cycles increases, and the rate of decrease becomes faster and faster. After 500 cycles, the capacity must not be less than 80% to qualify. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous article: Introduce a new maintenance method for lithium-ion batteries