LITHIUM COBALT OXIDE POSITIVE-ELECTRODE MATERIAL AND METHOD FOR FABRICATION THEREOF AND LITHIUM-ION RECHARGEABLE BATTERY

摘要

Provided is a lithium cobalt oxide positive-electrode material, said material being a composite structure having a doped lithium-cobalt-oxide substrate and surface coating; the general formula of said doped lithium-cobalt-oxide substrate is Li _1+zCo _1-x-yMa _xMb _yO ₂, wherein 0≤x≤0.01, 0≤y≤0.01 and -0.05≤z≤0.08; said Ma is a doped invariable-valence element, at least one of Al, Ga, Hf, Mg, Sn, Zn, and Zr; said Mb is a doped variable-valence element, at least one of Ni, Mn, V, Mo, Nb, Cu, Fe, In, W, and Cr; the surface coating layer is a high-voltage (4.5 V) positive-electrode material. By means of substitution doping of the variable-valence element, distortion resulting from delithiation of the layered structure is reduced by the maximum extent; the variable-valence element is doped by means of gaps, and during the process of charging, the oxidation of Co ³⁺is reconciled and delayed. The surface coating layer of the high-voltage positive-electrode material has a stable structure at voltages of 4.5 V or higher, and is capable of isolating an electrolyte solution and a lithium-cobalt-oxide substrate, thus reducing side reactions between the two and inhibiting the dissolution of transition metals; it also provides electrochemical energy.