Main Types Of Lithium Ion Batteries

According to the different electrolyte materials used in lithium-ion batteries, lithium-ion batteries are divided into liquid lithium ion battery (LIB) and polymer lithium ion battery (PLB).

Lithium ion battery (li--ion)

Rechargeable lithium-ion battery is the most widely used battery in modern digital products such as mobile phones and notebook computers, but it is "delicate" and cannot be overcharged or discharged in use (it will damage the battery or scrap it). Therefore, there are protective components or circuits on the battery to prevent expensive battery damage. Lithium ion battery charging is very demanding. To ensure that the termination voltage accuracy is within ± 1%, major semiconductor device manufacturers have developed a variety of lithium-ion battery charging ICs to ensure safe, reliable and fast charging.

Most mobile phones use lithium-ion batteries. The correct use of lithium-ion batteries is very important for prolonging battery life. It can be made into flat rectangle, cylinder, rectangle and button type according to the requirements of different electronic products, and has a battery pack composed of several batteries connected in series and parallel. The rated voltage of lithium-ion battery is generally 3.7V due to the change of material, and that of lithium iron phosphate (hereinafter referred to as ferrophosphate) cathode is 3.2V. When fully charged, the ending charging voltage is generally 4.2V and ferrophosphate 3.65v. The terminal discharge voltage of lithium-ion battery is 2.75V ~ 3.0V (the battery factory gives the working voltage range or terminal discharge voltage, and the parameters are slightly different, generally 3.0V and 2.5V for ferrophosphate). Continuous discharge below 2.5V (ferrophosphate 2.0V) is called over discharge, which will damage the battery.

Lithium ion batteries with positive electrode of lithium cobalt oxide type material are not suitable for high current discharge. Excessive current discharge will reduce the discharge time (higher internal temperature will be generated and energy will be lost), and may cause danger; However, lithium iron phosphate cathode material lithium battery can be charged and discharged with a large current of 20c or more (C is the capacity of the battery, such as c=800mah, 1c charging rate, i.e. the charging current is 800mA), which is especially suitable for electric vehicles. Therefore, the maximum discharge current given by the battery manufacturer shall be less than the maximum discharge current in use. The lithium-ion battery has certain requirements for temperature. The factory has given the charging temperature range, discharge temperature range and storage temperature range. Overvoltage charging will cause permanent damage to the lithium-ion battery. The charging current of lithium-ion battery shall be in accordance with the recommendations of the battery manufacturer, and the limited current circuit shall be required to avoid overcurrent (overheating). The commonly used charging rate is 0.25c ~ 1C. When charging with high current, it is often necessary to detect the battery temperature to prevent overheating damage to the battery or explosion.

Lithium ion battery charging is divided into two stages: constant current charging first, and constant voltage charging when it is close to the termination voltage. For example, a battery with 800MAH capacity has a termination charging voltage of 4.2V. The battery is charged at a constant current of 800mA (charging rate of 1c). At the beginning, the battery voltage is boosted at a large slope. When the battery voltage is close to 4.2V, it is changed to 4.2V constant voltage charging. The current gradually drops, and the voltage changes little. When the charging current drops to 1/10-50c (the setting values of each factory are different, which does not affect the use), it is considered that it is nearly full, and the charging can be terminated (some chargers start the timer at 1/10c, and end the charging after a certain time).