Explain the working principle and characteristics of lithium iron phosphate battery in detail

The working principle and characteristics of lithium iron phosphate batteries The full name of lithium iron phosphate batteries should be lithium iron phosphate batteries, the name is too long, simply put it is lithium iron phosphate batteries. Because its performance is particularly suitable for power applications, the word power was added to its name, that is, lithium iron phosphate power lithium-ion battery. Others call it a lithium-iron (life) power lithium-ion battery. Significance When I added this entry (April 24, 2013), cobalt (Co) is the most expensive and has a small amount of storage, nickel (Ni) and manganese (Mn) are cheaper, while iron (Fe) Is the cheapest. The price of cathode materials is also consistent with the prices of these metals. Therefore, lithium batteries made of LiFePO4 anode materials should be the cheapest. Another feature is that it does not pollute the environment. The requirements for rechargeable batteries are: high capacity, high output voltage, good charge and discharge cycle performance, stable output voltage, high current charge and discharge, electrochemical stability, safe use (not charged, discharge and short-circuit caused by improper operation, such as burning or Explosion), wide operating temperature range, non-toxic or less toxic, and no pollution to the environment. The anode of lithium iron phosphate lithium iron phosphate battery is good for these performance requirements, especially in large discharge rate discharge (5~10c discharge), the discharge voltage is stable, safe, will not burn, will not explode, and life (cycle), It has no pollution to the environment, it is the best, and the best battery high current output power. Structure and working principle The internal structure of LiFePO4 battery is shown in Figure 1. On the left is olivine LiFePO4, which is the positive electrode of the battery and is connected by aluminum foil. In the middle is a polymer film, which separates the positive and negative electrodes, but lithium ions can pass through, but electrons e- cannot. On the right is the negative electrode of a battery made of carbon (graphite), which is connected to the negative electrode of the battery through a copper foil. Between the upper and lower ends of the battery is the electrolyte of the battery, and the battery is enclosed in a metal casing. When the LiFePO4 battery is charged, the lithium ion Li+ of the positive electrode migrates to the negative electrode through the polymer film. During the discharge process, lithium ions in the negative electrode migrate to the positive electrode through the separator. Lithium batteries are named after lithium ions move back and forth between charge and discharge. The important performance is that its rated voltage is 3.2v, the cut-off voltage is 3.6v, and the cut-off voltage is 2.0v. Due to the different quality and technology of the positive electrode, negative electrode material and electrolyte material used by different manufacturers, their performance will be different. For example, the capacity of batteries of the same type (standard batteries in the same packaging) is quite different (10%~20%). The important performance of lithium iron phosphate power lithium ion battery is shown in Table 1. Compared with other rechargeable batteries, the performance of other rechargeable batteries is also listed in the table. It should be noted that there are certain differences in the performance parameters of lithium iron phosphate power lithium-ion batteries processed by different manufacturers; in addition, some battery performance is not included, such as battery internal resistance, self-discharge rate, charging and discharging temperature. Lithium iron phosphate batteries vary greatly in capacity and can be divided into three categories: small ones are only a few tenths of a milliamps, medium ones are only tens of milliamps, and large ones are only a few hundred milliamps. Similar parameters of different types of batteries also have certain differences. Analyzed the parameters of lithium iron phosphate power lithium ion battery. Dimensions: diameter 18mm, height 650mm (model 18650), the parameter performance is shown in Table 2. Over-discharge to zero-voltage test uses STL18650 (1100mAh) lithium iron phosphate power lithium-ion battery for zero-voltage discharge test. Test conditions: Charge the 1100mAh STL18650 battery for 0.5c, then discharge to 0C voltage, and discharge 1.0c. Then divide the 0V battery into two groups: one group for 7 days and the other group for 30 days; after the storage period expires, it is charged with 0.5c and discharged with 1.0c. Finally, the difference between the two zero-voltage storage periods is compared. 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: Analyze the service life, advantages and disadvantages of ternary lithium batteries