▎ 摘　　要

NOVELTY - Composite material comprises core and core shell, where the core is lithium-nickel-cobalt-manganese oxide, the chemical formula is LiNi1-x-yCoxMnyO2, x =0-1, y = 0-1, x≤ 0.2; the core-shell is lithium manganese iron phosphate, the chemical formula is LiFe1-aMnaPO4, a = 0.4-0.8. USE - Used as composite material. ADVANTAGE - The composite material: improves volume specific energy of the battery; and solves needle-puncture safety of the battery under the condition of 4.154.20 V full charge. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for preparing composite material, comprising (i) preparing Ni1-x-yCoxMny(OH)2precursor by co-precipitation method, (ii) sintering the Ni1-x-yCoxMny(OH)2precursor and lithium source at high temperature to obtain LiNi1-x-yCoxMnyO2, (iii) dispersing LiNi1-x-yCoxMnyO2in water at high speed to make suspended crystal nuclei, (iv) under the protection of nitrogen or inert gas, adopting co-precipitation method to precipitate a layer of iron(II) hydroxide and manganese(II) hydroxide on the surface of the suspended crystal nucleus co-precipitate Fe(1-a)Mna(OH)2 to obtain composite material precursor LiNi1-x-yCoxMnyO2+Fe(1-a)Mna(OH)2, and (v) under the protection of nitrogen or inert gas, mixing the composite material precursor LiNi1-x-yCoxMnyO2+Fe(1-a)Mna(OH)2 and lithium source, phosphorus sources, and sintering at high temperature to obtain LiNi1-x-yCoxMnyO2+LiFe(1-a)MnaPO4 core-shell composite material.