Working principle of lithium ion battery (LiFePO4)
The internal structure of lithium iron phosphate battery is shown in figure 1. On the left, LiFePO4 with olivine structure is used as the positive electrode of the battery, which is connected with aluminum foil. In the middle, a polymer diaphragm separates the positive electrode from the negative electrode, but lithium ion Li+ can pass through but electron e- cannot. On the right, the negative electrode of the battery is made of carbon (graphite) and connected with the negative electrode of the battery through copper foil. Between the upper and lower ends of the battery is the electrolyte of the battery, and the battery is sealed by a metal shell.
When lithium iron phosphate battery is charged, Li+ in the positive electrode migrates to the negative electrode through the polymer diaphragm. During discharge, Li+ in the negative electrode migrates to the positive electrode through the separator. Lithium-ion battery is named because lithium ion migrates back and forth during charging and discharging.
Main performance of lithium iron phosphate battery
The nominal voltage of LiFePO4 battery is 3.2 V, the terminal charging voltage is 3.6V, and the terminal discharging voltage is 2.0V V. Due to the different quality and technology of anode and cathode materials and electrolyte materials used by various manufacturers, their performance will be somewhat different. For example, the capacity of batteries of the same model (standard batteries in the same package) varies greatly (10% ~ 20%).
Characteristics of lithium iron phosphate battery
1, efficiency output: standard discharge 2 ~ 5c, continuous high current discharge up to 10C, instantaneous pulse discharge (10S) up to 20C；;
2. Good temperature-time performance: when the external temperature is 65℃, the internal temperature is as high as 95℃, and when the battery is discharged, the temperature can reach 160℃, so the battery structure is safe and intact;
3, the battery is damaged internally or externally, and the battery does not burn or explode, so the safety is the best;
4, the cycle life is good, and after 500 cycles, the discharge capacity is still greater than 95%;
5, discharge to zero volts without damage;
6, fast charging;
7. cost;
8. The environment is pollution-free.