Main Types Of Li-ion Batteries
According to the different electrolyte materials used in lithium-ion batteries, lithium-ion batteries are divided into liquid lithium-ion batteries (LIB for short), condensed lithium-ion batteries and polymer lithium-ion batteries (PLB for short).
1. Liquid lithium-ion battery
Rechargeable lithium-ion batteries are the most widely used batteries in modern digital products such as mobile phones and notebook computers. Therefore, there are protective components or protective circuits on the battery to prevent expensive battery damage. The charging requirements of lithium-ion batteries are very high. To ensure that the termination voltage accuracy is within ±1%, major semiconductor device factories have developed a variety of lithium-ion battery charging ICs to ensure safe, reliable and fast charging.
Mainstream mobile phones are equipped with lithium-ion batteries. Proper use of lithium-ion batteries is very important to prolong battery life. It can be made into flat rectangle, cylinder, rectangle and button type according to the requirements of different electronic products, and it has a battery pack composed of several batteries connected in series and parallel. The rated voltage of lithium-ion batteries is generally 3.7V due to changes in materials, and 3.2V for lithium iron phosphate positive electrodes. The termination charging voltage when fully charged is generally 4.2V, and lithium iron phosphate is 3.65V. The termination discharge voltage of lithium-ion batteries is 2.75V~3.0V (the battery factory gives the working voltage range or the termination discharge voltage, each parameter is slightly different, generally 3.0V, and 2.5V for ferrophosphorus). Continued discharge below 2.5V (lithium iron phosphate 2.0V) is called over-discharge, which will damage the battery.
Lithium-ion batteries with lithium cobalt oxide materials as the positive electrode are not suitable for high-current discharge. Excessive current discharge will reduce the discharge time (higher temperature will be generated inside and energy will be lost), and may be dangerous; but lithium iron phosphate The positive electrode material lithium battery can be charged and discharged at a high current of 20C or even higher (C is the capacity of the battery, such as C=800mAh, and the charging rate of 1C means that the charging current is 800mA), which is especially suitable for electric vehicles. Therefore, the battery production factory gives the maximum discharge current, which should be less than the maximum discharge current in use. Lithium-ion batteries have certain temperature requirements. The factory provides 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 the lithium-ion battery should be based on the battery manufacturer's suggestion, and a current-limiting circuit is required to avoid over-current (overheating). Generally, 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 from damaging the battery or causing an 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 a capacity of 800mAh has a termination charging voltage of 4.2V. The battery is charged with a constant current of 800mA (charging rate 1C). At the beginning, the battery voltage is boosted with a large slope. When the battery voltage is close to 4.2V, it is changed to 4.2V constant voltage charging. The current drops gradually, and the voltage does not change much. When the charging current drops to 1/10-50C (the setting value of each factory is different, it does not affect the use), it is considered to be close to full, and the charging can be terminated (some chargers start the timer after reaching 1/10C, after a certain period of time end charging).
2. Condensed-state lithium-ion battery
On April 19, 2023, CATL released condensed matter batteries with a maximum energy density of 500Wh/kg, and mass production capacity will be available within 2023.
