Software simulation shows that for applications on 18650 batteries, the cost of using LiCoPO4 cathode material is about 7W.h per dollar. There are four main types of Li-Co-P-O series materials: LiCoPO4, LiCo (PO3) 3, LiCo2P: O10, and Li6Co5 (P2O7) 4. LiCo (PO3) 3 does not have delithium electrochemical activity in the range of 1 ~ 5V.LiCoPO4 has an olivine structure, an orthorhombic system, and a density of 3.76g / cm2, which is usually described as an oxygen hexagonal close-packed. Li and Co are located in half of the octahedron position, P occupies 1/8 of the tetrahedron, and is on the BC plane. The upper CoO6 octahedron shares four corners and is connected by the PO4 group along the a-axis, and lithium ions move along the a-axis of the edge-sharing LiO6 octahedron. Theoretical calculations show that the olivine structure LiCoPO4 can be transformed into a Na2CrO4 structure under the pressure of 0K and 4GPa. It consists of an edge-sharing CoO6 octahedron, connected by a PO4 tetrahedron along the a-axis, and (CoO6) (PO4) on the ac surface. The tetrahedral position in the layer is occupied by lithium ions and separated from each other. Lithium ion diffusion requires higher activation energy. Such high molecular isoforms have no value in battery applications, but can provide useful data for basic research; further increase in pressure can also transform into spinel structures. For LiCoPO4, with lithium deintercalation, the valence state of the transition metal increases, and there will be a hybrid phenomenon of P 3p electrons and 3d electron orbitals of the transition metal.

     Single crystal with a diameter of 5mm and a length of 50 ~ 70mm. The color is dark purple. The unit cell parameters of LitCoPO4 with olivine structure are a = 1.02nm, b = 0.592nm, c = 0. 47nm. : Reports vary by laboratory. Nyten reports that the unit cell volume V is approximately 0.2905 nm. The unit cell parameters a and 6 increase with the increase in lithium content, and the unit cell parameter c generally decreases with the change in lithium content, but only slightly increases when the lithium content is less than 0.5. The unit cell volumes of LiCoPO4 and CoPO4 calculated by density function theory are 0.32831595nm3 and 0.2758254nm3, respectively. Unlike the olivine structure FePO4, the existence of CoPO4 with the same space group has not been confirmed. The composition of the Lir CoPO4 system is not very clear at present, that is, the material's lithium deintercalation mechanism is not clear, which is probably related to the difficulty of preparing the pure phase. It is generally believed that LiFePO4 is composed of two phases under different charge states Composition, namely Li, FePO4 phase and Li, FePO4 phase, x is very close to 0, y is very close to 1; for the phase composition of LiCoPO4 electrode material under different state of charge is not clear, Ehrenberg thinks it is LiCoPO4, The three-phase mixture of Li.CoPO, and CoPO4, where the z value is about 0.6 ~ 0.7, and the phase transition reaction is a first order reaction.

     Pure olivine-structured phosphate is a semiconductor or insulator. The room temperature conductivity is about 10-10S / cm, and the conductivity is about 0.51eV. Partial replacement of Co by Fe decreases the activation energy, and partial replacement of Ni by Ni decreases the electrical conductivity: Rissouli The value is 0.62eV. It is reported that the room temperature DC conductivity of the heat treated sample in air is 10 S / cm, and the room temperature DC electronic conductivity of the heat treated sample in chlorine gas is 10-5 ~ 10-4S / cm. These data are questionable because Impurity content and type are unknown. Wolfensine et al. Found that the impurity CoeP can effectively improve the electrical conductivity of LiCoPO. The conductivity reported by different laboratories is very different, on the one hand, it is related to the particle size and morphology of the material; on the other hand, the type of impurity content is difficult to control.