Factors affecting the charging performance of lithium-ion batteries
Lithium-ion battery charger
When charging lithium-ion batteries, the charging current and voltage should be controlled sequentially according to time. Overcharging should be avoided, as it can easily damage the battery. Therefore, research on dynamic lithium-ion battery chargers must clearly understand their charge-discharge characteristics, namely the key factors affecting the charging performance of lithium-ion batteries: voltage, current, and temperature. Only on this basis can further research be conducted.
1. Voltage. The nominal voltage of a lithium-ion battery is generally 3.6V or 3.7V (depending on the manufacturer). The charging termination voltage (also called the floating voltage) is generally 4.1V, 4.2V, etc., depending on the specific electrode material. Generally, the termination voltage is 4.2V when the cathode material is graphite and 4.1V when the cathode material is carbon. For the same battery, even if the initial voltage is different, the termination voltage will reach the same level when the battery capacity reaches 100%. During the charging process of a lithium-ion battery, if there is electrical...
If the pressure is too high, excessive heat will build up inside the battery, potentially damaging the battery's structure or causing a short circuit. Therefore, it is necessary to monitor the battery's charging voltage and keep it within the allowable range.
2. Currently. During charging, the charging current must be controlled. The maximum charging current of a battery is determined by its rated capacity. The nominal capacity symbol is C, and the unit is ampere-hours (Ah). The calculation method is: C = IT(1-1), where I is the constant current discharge current and T is the discharge time. For example, it takes 1 hour to fully charge a 50Ah battery using a 50A current. In this example, the charging rate is 1C, and the general charging rate is between 0.1-1C. Generally speaking, based on the different charging rates, the charging process can be divided into three types: slow charging (also called fine current charging), fast charging, and ultra-fast charging. Slow charging current is between 0.1C and 0.2C; fast charging current is greater than 0.2C and less than 0.8C; ultra-fast charging current is greater than 0.8C. Because the battery has a certain internal resistance, its internal heat is related to the current. When the battery's operating current is too high, its heat generation will cause the battery temperature to rise beyond the normal value, affecting battery safety and even causing an explosion. In the initial stage of charging, if the battery is discharged too deeply, it is impossible to directly charge the battery with a large current. As charging continues, the battery's ability to accept current increases. Therefore, during battery charging, the charging current must be controlled according to the battery's specific state.
3. Temperature. Battery performance is also affected by battery temperature. Too low a temperature will affect the activity of the internal materials, while too high a temperature will damage the structure of the internal materials. Generally, the ideal temperature range is -20℃ to +65℃.
