What is the main working principle of lithium iron phosphate battery?

The interior of lithium ion battery is mainly composed of positive electrode, negative electrode, electrolyte and diaphragm. Because of the different materials and processes of anode, cathode and electrolyte, batteries have different characteristics and different names. At present, the cathode materials of lithium-ion batteries on the market are mainly lithium cobaltate (LiCoO2) and lithium manganate (LiMn2O4), and there are also a few lithium-ion batteries that use lithium nickelate (LiNiO2) as cathode materials. The newly developed lithium iron phosphate battery is a new member of the lithium ion battery family, which uses lithium iron phosphate (LFP) as the positive electrode.

Figure 1: Working principle of lithium iron phosphate battery

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 charging lithium iron phosphate battery, 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.

Lithium iron phosphate battery has unparalleled advantages and can be widely used in many fields. According to the popularity of the market, the application of lithium ferrous phosphate can be roughly divided into three stages:

The first stage (now more extensive):

1. Power tools: electric drill, chainsaw, lawn mower, etc. ?

2. Remote control of toys such as cars, boats and planes;

3. Uninterruptible power supply (UPS) and emergency lights, warning lights and miner's lights (the best safety); ?

4. Replace the 3V disposable lithium battery and 9V nickel-cadmium or nickel-hydrogen rechargeable battery in the camera (the size is exactly the same);

The second stage (currently emerging):

1. Light electric vehicles: electric bicycles, golf carts, small flat-panel battery cars, forklifts, cleaning vehicles, electric wheelchairs, etc. ?

2. Solar energy and wind energy storage equipment;

3. Small medical instruments and portable instruments.

The third stage (currently promoted by the government):

1. Large electric vehicles: buses, cars, scenic spots and hybrid vehicles.