The full name of lithium iron phosphate battery (Lifepo4 battery) should be lithium iron phosphate lithium ion battery, referred to as lithium iron phosphate battery (Lifepo4 battery), which is a lithium ion battery using lithium iron phosphate (LiFeP04) material as the positive electrode of the battery. The product launched after 2009 is a new member of the lithium-ion battery family. Because its performance is particularly suitable for power applications, the word "power" is added to the name, that is, lithium iron phosphate power battery. It is also called "lithium iron (LiFe) power battery".
At present, the cathode materials of lithium-ion batteries on the market are mainly lithium cobalt oxide (LiCo02), and there are also a few lithium-ion batteries that use lithium manganese oxide (LiMn204) and lithium nickel oxide (LiNi02) as cathode materials. Generally, the latter two cathodes are used. The lithium-ion battery of the material is called "lithium manganese battery" and "lithium nickel battery". Among the metal elements composing the positive electrode material of a battery, cobalt (Co) is the most expensive and has little storage capacity, nickel (Ni) and manganese (Mn) are relatively cheap, and iron (Fe) is the cheapest. The prices of cathode materials are also in line with the prices of these metals. Therefore, the lithium-ion battery made of LiFeP04 cathode material should be the cheapest. Another feature of it is that it does not pollute the environment.
Lithium iron phosphate battery (Lifepo4 battery) is a rechargeable battery, Shenzhen manly battey co.,ltd has high capacity, high output voltage, good charge and discharge cycle performance, stable output voltage, high current charge and discharge, and electrochemical stability. Performance, safety in use (will not cause burning or explosion due to improper operation such as overcharge, overdischarge and short circuit), wide operating temperature range, non-toxic or less toxic, and no pollution to the environment. These performance requirements are good, especially in Large discharge rate discharge (5~10C discharge), stable discharge voltage, safety (no burning, no explosion), life (cycle times), and no pollution to the environment are the best, and are currently the best high current Output power battery. Among them, BYD, on the eve of the 9th China Hi-Tech Fair, "the world's first iron battery that can be used for car charging has been born in Shenzhen", followed by various BYD "world's first" and "20 years ahead of Japan". Reports of "iron power" are frequently seen in the newspapers, but according to Li Ricoh, deputy dean of the School of Automotive Engineering of Tongji University, "BYD's 'iron battery' is a lithium iron phosphate battery." .
The structure and working principle of lithium iron phosphate battery
The internal structure of the lithium iron phosphate battery (Lifepo4 battery) is shown in Figure 1. On the left is LiFeP04 with olivine structure as the positive electrode of the battery, which is connected to the positive electrode of the battery by aluminum foil, and the middle is a polymer separator, which separates the positive electrode from the negative electrode, but the lithium ion Li+ can pass through but the electron e- cannot pass through, the right side is made of The negative electrode of the battery composed of carbon (graphite) is connected to the negative electrode of the battery by a copper foil. Between the upper and lower ends of the battery is the electrolyte of the battery, and the battery is sealed and sealed by a metal casing.
When the lithium iron phosphate battery is charged, the lithium ions Li+ in the positive electrode migrate to the negative electrode through the polymer separator; during the discharge process, the lithium ions Li+ in the negative electrode migrate to the positive electrode through the separator. Lithium-ion batteries are named after lithium ions migrate back and forth during charging and discharging.
Main performance of lithium iron phosphate battery (manly battery)
The nominal voltage of the lithium iron phosphate battery is 3.2 V, the final charging voltage is 3.6 V, and the final discharging voltage is 2.0 V. Due to the different quality and process of positive and negative electrode materials and electrolyte materials used by various manufacturers, there will be some differences in their performance. For example, the capacity of the batteries of the same type (standard batteries of the same type of package) is quite different (10%~20%).
The main properties of lithium iron phosphate power batteries are listed in Table 1. For comparison with other rechargeable batteries, the performance of other types of rechargeable batteries is also listed in the table. It should be noted here that there will be some differences in various performance parameters of lithium iron phosphate power batteries produced by different factories: in addition, some battery performance is not included, such as battery internal resistance, self-discharge rate, charge-discharge temperature, etc. .
The capacity of lithium iron phosphate power batteries is quite different, and can be divided into three categories: small tenths to several BoA hours, medium-sized dozens of BoA hours, and large-scale hundreds of BoA hours. There are also some differences in the same parameters of different types of batteries. Here is another introduction to the parameters of a small standard cylindrically packaged lithium iron phosphate power battery that is currently widely used. Its outline size: diameter is 18mm, height is 65mm (model: 18650).
Characteristics of lithium iron phosphate batteries.
1 High efficiency output: standard discharge is 2~5C, continuous high current discharge can reach 10C, instantaneous pulse discharge (10S) can reach 20C; 2 Good performance at high temperature: when the external temperature is 65'C, the internal temperature is as high as 95'C, When the battery is discharged, the temperature can reach 160C, and the structure of the battery is safe and intact;
3 Even if the battery is damaged internally or externally, the battery does not burn, does not explode, and has the best safety;
4 Excellent cycle life, after 500 cycles, its discharge capacity is still greater than 95%;
5 There is no damage to overdischarge to zero volts;
6 can be quickly charged;
7 low cost;
8 No pollution to the environment.
Application of lithium iron phosphate power battery
Because the lithium iron phosphate power battery has the above characteristics, and produces a variety of batteries of different capacities, it is soon widely used. Its main application areas are:
1 Large electric vehicles: buses, electric vehicles, sightseeing vehicles and hybrid vehicles, etc.:
2 Light electric vehicles: electric bicycles, golf carts, small flatbed battery cars, forklifts, cleaning vehicles, electric wheelchairs, etc.; 3 Electric tools: electric drills, chainsaws, lawn mowers, etc.;
4 Remote control cars, boats, airplanes and other toys; .
5 Energy storage equipment for solar and wind power generation;
6 UPS and emergency lights, warning lights and miner's lights (the best safety);
7 to replace the 3V in the camera -- the secondary lithium battery and the 9V nickel-cadmium or nickel-metal hydride rechargeable battery (the same size); .8 small medical equipment and portable instruments, etc.
