In the crystal structure of Lifepo4 Battery, oxygen atoms are arranged in a hexagonal close-packed arrangement. PO4 tetrahedron and FeO6 octahedron constitute the spatial skeleton of the crystal, Li and Fe occupy the octahedral void, and P occupies the tetrahedral void. Among them, Fe occupies the common angular position of the octahedron, and Li occupies the common edge position of the octahedron. FeO6 octahedrons are connected on the bc plane of the crystal, and LiO6 octahedron structures in the b-axis direction are combined to form a chain structure. One FeO6 octahedron is co-edge with two LiO6 octahedrons and one PO4 tetrahedron.
Due to the discontinuity of the FeO6 co-edge octahedron network, no electronic conductivity can be formed; at the same time, the PO4 tetrahedron limits the volume change of the lattice affects the deintercalation and electron diffusion of Li + and leads to the electronic conductivity and ion diffusion of the Lifepo4 Battery cathode material Extremely inefficient.
The theoretical specific capacity of Lifepo4 Battery is high (about 170mAh / g), and the discharge platform is 3.4V. Li + moves back and forth between the positive and negative poles to achieve charge and discharge. An oxidation reaction occurs during charging. Li + moves out of the positive electrode and is inserted into the negative electrode through the electrolyte. Iron changes from Fe2 + to Fe3 + and an oxidation reaction occurs.