Lithium nickel cobalt aluminum oxide positive electrode material and preparation method therefor

Abstract

The invention provides a lithium nickel cobalt aluminum oxide positive electrode material and a preparation method therefor. A nickel cobalt aluminum precursor is prepared by mixing a metal salt solution comprising Ni<2+>, Co<2+> and Al<3+>, and a complexing agent solution and a precipitator solution by adopting a liquid phase control crystallization method, wherein the complexing agent comprisesone or more of fluoride, an alcohol amine type compound, a phosphoric acid type compound and a carbonyl compound; and the nickel cobalt aluminum precursor and a solid-phase lithium source are mixed and sintered to obtain the lithium nickel cobalt aluminum oxide positive electrode material. Through complexing between the limited complexing agent and Al<3+>, the nucleating rate of Al<3+> is lowered,so that uniform coprecipitation and crystallization among Al<3+> and Ni<2+> and Co<2+> can be ensured, thereby obtaining the spherical Ni<x>Co<y>Al<z>(OH)<2> precursor with uniform grain fineness distribution and high tap density; and therefore, the obtained lithium nickel cobalt aluminum oxide positive electrode material is uniform in composition and high in uniformity.

Description

technical field [0001] The invention belongs to the technical field of lithium-ion batteries, and in particular relates to a nickel-cobalt-lithium-aluminate cathode material and a preparation method thereof. Background technique [0002] With the increasingly high requirements for lithium-ion batteries in electric vehicles, high-end 3C digital and other fields, lithium nickel cobalt aluminate LiNi x co y Al z o 2 Cathode materials have great development prospects due to their high specific capacity, strong cycle capacity, and good stability. Due to the smallest specific surface area, spherical particles can effectively reduce the side reaction between the cathode material and the electrolyte, thereby effectively inhibiting the loss of battery capacity, and the spheroidization of cathode materials is an important development trend at present. [0003] The acquisition of spherical positive electrode materials benefits from the control of the morphology of the precursors du...

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Problems solved by technology

[0005] However, methods (1) and (2) are not only complicated in process, but also the prepared precursors are likely to cause uneven distribution of elements, thereby resulting in uneven composition of the positive electrode material and deteriorating the performance of the positive electrode material; the precursor prepared by method (3) Compared with methods (1) and (2), the uniformity of bulk element distribution is improved and the process is simple, but due to the amphoteric nature of aluminum, excessive precipitant will make the precipitated Al(OH) 3 Dissolution, anti-dissolution phenomenon occurs, so that the composition of the precursor deviates from the stoichiometric ratio

Furthermore, Al(OH) 3 (K sp =1.3×10 -33 ) Concentration product constant ratio Ni(OH) 2 (K sp =2.0×10 -15 ), Co(OH) 2 (K sp =1.9×10 -15 ) concentration product constant eighteen orders of magnitude smaller, and Ni 2+ and Co 2+ In contrast, under the same reaction conditions, Al 3+ Very easy to precipitate, quickly generate colloidal particles, difficult to mix with Ni 2+ 、Co 2+ Uniform co-precipitation will still cause uneven distribution of precursor elements or even phase separation, and then the obtained positive electrode material composition will be uneven

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