What is lithium iron phosphate battery?

Lithium iron phosphate battery is a lithium ion battery with lithium iron phosphate (LiFePO4) as the cathode material and carbon as the cathode material. The rated voltage of the single battery is 3.2V, and the charging cut-off voltage is 3.6V~3.65V.
During the charging process, some lithium ions of lithium iron phosphate will escape, and the electrolytic mass will be transferred to the cathode and embedded with carbon material. At the same time, electrons are released from the anode and arrive from the external circuit to maintain the balance of chemical reaction. In the discharge process, lithium ions escape through magnetic force, arrive through the electrolytic mass, release at the same time, arrive in the external circuit, and provide energy to the outside.

Lithium iron phosphate battery has the advantages of high working voltage, high energy density, long cycle life, good safety, low self discharge rate and no memory.
In the crystal structure, oxygen atoms are closely arranged in six characters. PO43 tetrahedron and FeO6 form the spatial skeleton of the crystal, Li and Fe occupy the octahedron gap, P occupy the tetrahedron gap, where Fe occupies the co angular position and Li occupies the covariant position. FeO6 is connected with each other on the BC plane of the crystal, and the octahedral structure of LiO6 in the B axis direction is connected with each other in a chain structure. One FeO6, two LiO6 and one PO43 tetrahedron coexist.

The total network of FeO6 is discontinuous, so it cannot form conductivity. On the other hand, PO43 tetrahedron restricts the volume change of the lattice and affects the ablation and diffusion of Li, resulting in extremely low electronic conductivity and ion diffusion efficiency of the cathode material.

Theoretically, the battery has a high capacity (about 170mAh/g), and the discharge platform is 3.4V. Li goes back and forth between charging and discharging. During charging, oxidation reaction occurs, and Li escapes. The electrolytic substance is embedded in the cathode, and iron is transformed from Fe2 to Fe3, and oxidation reaction occurs.

What are the structural characteristics of lithium iron phosphate battery?

The left side of the lithium iron phosphate battery is made of olivine material, which is connected with the battery by aluminum foil. On the right is the battery cathode composed of carbon (graphite), which is connected by copper foil and the battery cathode. In the middle is the membrane of the separated polymer. Lithium can pass through the membrane, not the membrane. The inside of the battery is filled with electrolytic substance, and the battery is sealed with a metal shell.

What is the principle of battery charging and discharging?

The charge discharge reaction of lithium iron phosphate battery takes place between LiFePo4 and FePO4. During charging, the ions separated from lithium form FePO4, and during discharging, lithium ions embed FePO4 to form LiFePo4.

When the battery is charged, lithium ions move from the lithium iron phosphate crystal to the crystal surface, enter the electrolytic substance under the effect of electric field force, pass through the diaphragm, and then move to the surface of graphite crystal through the electrolyte, and then embedded in the graphite lattice. On the other hand, the copper foil collector flows through the conductor to the aluminum foil collector, through the lug, battery column, external circuit, ear to the battery cathode, and through the conductor to the graphite cathode. The charge balance of the cathode. After lithium ions are dephased from lithium iron phosphate, lithium iron phosphate is converted into iron phosphate.