The charging process and principle analysis of 18650 lithium battery

Some chargers are implemented by cheap methods, and the control accuracy is not good enough, which may cause abnormal battery charging and even damage the battery. When choosing a charger, try to choose a big brand of 18650 lithium battery charger, the quality and after-sales are guaranteed, and the service life of the battery is extended. The brand-guaranteed 18650 lithium battery charger has four protections: short-circuit protection, over-current protection, over-voltage protection, battery reverse connection protection, etc. Overcharge protection: When the charger overcharges the lithium battery, it needs to terminate the charging state in order to guard against the increase in internal pressure caused by the temperature rise. For this reason, the protection device needs to monitor the battery voltage, and when it reaches the battery overcharge voltage, it activates the overcharge protection function and stops charging. Over-discharge protection: In order to guard against the over-discharge status of the lithium battery, when the voltage of the lithium battery is lower than its over-discharge voltage test point, the over-discharge protection is activated, the discharge is stopped, and the battery is kept in a low quiescent current standby mode. Over-current and short-circuit protection: When the discharge current of the lithium battery is too large or a short-circuit condition occurs, the protection device will activate the over-current protection function. Lithium battery charging control is divided into two stages. The first stage is constant current charging. When the battery voltage is lower than 4.2V, the charger will charge with a constant current. The second stage is the constant voltage charging stage. When the battery voltage reaches 4.2V, due to the characteristics of lithium batteries, if the voltage is higher, it will be damaged. The charger will fix the voltage at 4.2V and the charging current will gradually decrease. When it is reduced to a certain value (usually when the current is set at 1/10), the charging circuit is cut off, the charging completion indicator light is on, and the charging is completed. Excessive charging and discharging of lithium batteries can cause permanent damage to the positive and negative electrodes. Excessive discharge causes the negative carbon sheet structure to collapse, and the collapse will cause the lithium ions to be unable to be inserted during the charging process; overcharging causes too many lithium ions to be inserted into the negative carbon structure, causing some of the lithium ions to be unable to be released anymore. The charging principle of 18650 lithium battery The working principle of lithium battery refers to its charging and discharging principle. When the battery is charged, lithium ions are generated on the positive electrode of the battery, and the generated lithium ions move to the negative electrode through the electrolyte. The carbon as the negative electrode has a layered structure. It has many micropores. The lithium ions that reach the negative electrode are embedded in the micropores of the carbon layer. The more lithium ions are inserted, the higher the charging capacity. In the same way, when the battery is discharged (that is, the process when we use the battery), the lithium ions embedded in the carbon layer of the negative electrode are released and move back to the positive electrode. The more lithium ions returned to the positive electrode, the higher the discharge capacity. What we usually call battery capacity refers to the discharge capacity. It is not difficult to see that during the charging and discharging process of lithium batteries, lithium ions are in a state of movement from positive to negative to positive. If we compare the lithium battery to a rocking chair, the two ends of the rocking chair are the two poles of the battery, and the lithium ion is like an excellent athlete running back and forth on both ends of the rocking chair. Therefore, the experts gave the lithium battery a lovely name, rocking chair battery. 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 post: Do I have to use a lithium battery management chip to charge a lithium iron phosphate battery?