Coated modified LiNi<0.7>Co<0.1>Mn<0.2>O<2> ternary anode material and preparation method thereof and battery

Abstract

The invention discloses a coated modified LiNi<0.7>Co<0.1>Mn<0.2>O<2> ternary anode material and a preparation method thereof and a battery. The preparation method of the ternary anode material comprises the steps that during preparation of a nickel-cobalt-manganese hydroxide precursor, magnesium elements are introduced first, and then an ammonium molybdate aqueous solution is used as a complexingagent in the later period of a coprecipitation reaction; after ammonium molybdate is hydrolyzed in water, ammonia ions and molybdate ions appear, the ammonia ions are used as a complexing agent for compensating for the coprecipitation reaction, the molybdate ions are partially deposited on the surface of the nickel-cobalt-manganese hydroxide precursor formed in a precipitation reaction phase, andin-situ introduction of molybdenum elements is realized; and then ternary anode powder with surfaces containing the molybdenum elements is obtained through lithiation treatment. According to the method, by adding the magnesium elements and doping the molybdenum elements in situ on the surface, the charge / discharge performance, circulation performance and the like of the obtained modified ternaryanode powder are effectively improved.

Description

technical field [0001] The invention relates to a nickel-cobalt-manganese ternary positive electrode material with high nickel content, in particular to a coated modified LiNi 0.7 co 0.1 mn 0.2 o 2 Ternary positive electrode material and its preparation method and battery. Background technique [0002] Lithium-ion batteries use materials capable of reversible intercalation and extraction of lithium ions as the positive and negative electrode materials of the battery, combined with an appropriate electrolyte or solid electrolyte powder film to form a lithium-ion secondary battery system. Because the energy of a battery depends on the product of its voltage and capacity, the means to increase the energy density of the battery is to use positive and negative materials with high voltage and high capacity. For the same negative electrode material, the higher the capacity and potential of the positive electrode material, the higher the energy density of the battery. Improving...

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Problems solved by technology

[0008] Although there are a variety of ternary positive electrode powder surface coating or doping treatment methods as mentioned above, they are all coating layers superimposed on the surface of the ternary positive electrode powder, and there is no method based on doping metal elements to replace the surface part of the ternary positive electrode powder. The nickel, cobalt, and manganese atoms in the crystal structure, that is to say, did not take advantage of the high valence of metal elements to reduce the valence changes of nickel, cobalt, and manganese elements in the layered crystal structure during charge and discharge, and did not take into account the The doping of high valence metal elements in the layered crystal structure leads to an increase in the concentration of vacancies, which facilitates the diffusion of lithium ions to achieve the purpose of improving the performance of the ternary cathode powder through doping

On the other hand, those skilled in the art know that the surface of high nickel content ternary positive electrode powder is alkaline, if it is directly applied to the subsequent pulping process, it will The problem of causing the slurry to become a gel (jelly-like colloid); if you want to remove the surface alkalinity of the ternary positive electrode powder, although you can use water washing, this will cause the loss of lithium ions on the surface and cause the discharge of the ternary positive electrode material Capacity reduction

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