Lithium-ion battery principle
A lithium-ion battery is a rechargeable battery consisting of two materials that can intercalate and deintercalate lithium ions, serving as the positive and negative electrodes. It operates by transferring lithium ions between the positive and negative electrodes. During charging and discharging, Li+ ions move between the positive and negative electrodes. During discharge, the anode oxidizes, losing electrons, while the cathode is reduced, gaining electrons; during charging, the charge movement is reversed.
Lithium-ion batteries are divided into lithium-ion batteries and lithium-ion batteries. Currently, mobile phones and laptops use lithium-ion batteries, which are commonly referred to as lithium-ion batteries. However, true lithium-ion batteries are not used in everyday electronic products due to their high safety risks.
During the insertion and extraction of lithium ions, an equivalent number of electrons are simultaneously inserted and extracted (conventionally, the positive electrode is referred to as insertion or extraction, while the negative electrode is referred to as insertion or extraction). During charging and discharging, lithium ions shuttle back and forth between the positive and negative electrodes, being inserted/extracted and inserted/extracted, which is figuratively called a rocking chair battery.
Lithium-ion batteries have high energy density and high average output voltage. They have low self-discharge, below 10% per month. They have no memory effect. They have a wide operating temperature range of -20℃ to 60℃. They exhibit excellent cycle performance, can be charged and discharged quickly with a charging efficiency of up to 100%, and have high output power. They have a long lifespan. They are environmentally friendly and are known as green batteries.
Lithium-ion battery charging methods
1. Pre-charge stage. After the DC power is connected, when the lithium-ion battery is detected, the charging chip is activated to enter the pre-charge process. During this period, the charging controller charges the battery with a relatively small current to restore the battery voltage and temperature to normal.
2. Constant Current Charging Stage. In the initial stage of charging, the charging circuit charges the lithium-ion battery with a constant current. Typically, lithium-ion batteries use a standard charging rate. During constant current charging, the battery voltage will rise slowly. Once the battery voltage reaches the set termination voltage, constant current charging will terminate, and the constant voltage charging process will begin.
3. Constant voltage charging stage. During the constant voltage charging process, the charging current will gradually decrease. When the charging current drops below the set value or the full charge time is exceeded, the charging will switch to the top-end cut-off stage. At this time, the charging controller will replenish the battery with a very small charging current. Under normal circumstances, this process can extend the battery's usage time by 5% to 10%.
