DOUBLE-LAYER COATED TERNARY MATERIAL AND PREPARATION METHOD THEREFOR, AND LITHIUM-ION BATTERY

A double-layer coated ternary material and a preparation method therefor, and a lithium-ion battery. The double-layer coated ternary material comprises a monocrystalline high-nickel ternary material, a polycrystalline nanometer ternary material layer coated outside the monocrystalline high-nickel ternary material, and a modification compound layer coated outside the polycrystalline nanometer ternary material layer, wherein the modification compound layer comprises a B-containing compound and an Al-containing compound. By coating the monocrystalline high-nickel ternary material with the polycrystalline nanometer ternary material, the rate capability and specific discharge capacity of the material can be improved, and the impedance can be reduced. The modification compound layer can integrate the advantages of the B-containing compound and the Al-containing compound, and can effectively improve the first-cycle specific charge-discharge capacity, initial efficiency, normal-temperature cycle performance and high-temperature cycle performance of the double-layer coated ternary material.