Explanation of the structure and working principle of lithium iron phosphate battery

The full name of lithium iron phosphate battery is lithium iron phosphate battery, this name is too long, referred to as lithium iron phosphate battery. Because its performance is particularly suitable for power applications, the word power was added to the name, that is, lithium iron phosphate power lithium-ion battery. Some people also call it a lithium-iron (life) power lithium-ion battery. Working principle Lithium iron phosphate battery refers to a lithium battery using lithium iron phosphate as the positive electrode material. Lithium battery cathode materials mainly include lithium cobalt acid, lithium manganese acid, lithium nickel acid, ternary materials, and lithium iron phosphate. Lithium cobalt oxide is the negative electrode material for most lithium batteries. Significance In the metal market, cobalt (Co) is the most expensive, and there is not much storage, nickel (Ni) and manganese (Mn) are cheaper, and iron (Fe) is stored more. The price of anode material is consistent with the price of these metals. Therefore, LiFePO4 cathode materials made of lithium batteries should be quite cheap. Another feature of it is that it is environmentally friendly and pollution-free. 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, 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 LiFePO4 is used as the positive electrode of the battery and is connected to the positive electrode of the battery through aluminum foil. In the middle is a polymer film, which separates the positive and negative electrodes, but lithium ions Li can pass through, but electrons e- cannot. On the right is the negative electrode of the battery, which is made of carbon (graphite) and is connected to the negative electrode of the battery with copper foil. Between the upper and lower ends of the battery is the battery electrolyte, which is sealed in a metal box. When the LiFePO4 battery is charged, the positive lithium ion Li migrates to the negative electrode through the polymer membrane. During the discharge process, lithium ions in the negative electrode migrate to the positive electrode through the separator. Lithium batteries are named after the fact that lithium ions move back and forth between charging and discharging. The important performance of the battery is that the rated voltage is 3.2v, the terminal charging voltage is 3.6v, and the terminal discharging voltage is 2.0v. Due to the different quality and technology of anode, cathode, and electrolyte materials used by various manufacturers, there are also certain differences in their performance. For example, the battery capacity of the same model (standard battery in the same package) varies greatly (10%~20%). It should be noted that the performance parameters of lithium iron phosphate batteries processed by different manufacturers are different; in addition, there are some battery performances that are not included, such as battery internal resistance, self-discharge rate, charge and discharge temperature, etc. The capacity of lithium iron phosphate power lithium-ion batteries is very different and can be divided into three types: the small ones are only a few tenths of a milliamps, the medium ones are only tens of milliamps, and the large ones are only a few hundred milliamps. Different types of batteries also have some differences in the same parameters. Overdischarge to zero voltage test: Use STL18650 (1100mAh) lithium iron phosphate power lithium ion battery to do zero voltage discharge test. Test conditions: charge 1100mAh STL18650 battery for 0.5c, discharge to 0C voltage, and discharge 1.0c. Divide the 0V battery into two groups: one group for 7 days and the other group for 30 days. After the storage period expires, charge 0.5c and discharge 1.0c. Finally, the difference between the two zero-voltage storage periods is compared. The test results show that after 7 days of zero-voltage storage, the battery has no leakage, good performance, and a capacity of 100%. After 30 days, there was no leakage, good performance, 98% output; after 30 days of storage, the battery was charged and discharged three times, and the capacity was restored to 100%. 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: New solid electrolyte can increase the energy density of lithium batteries