Multi-stage core and shell structure multi-element material, precursor thereof and preparation method for multi-stage core and shell multi-element material and precursor

Abstract

The invention relates to a multi-stage core and shell structure multi-element material precursor used for an anode material of a lithium ion battery. The molecular formula of the multi-stage core and shell structure multi-element material precursor is (1-x)Li[NiaMnbCo1-a-b][OH]2 x [NimConM1-m-n][OH]2, wherein M=Mn, Al, Mg andTi, the x is larger than or equal to 0.2 and smaller than or equal to 0.9, the a is larger than or equal to 1/3, the b is smaller than or equal to 1/2, the m is larger than or equal to 0.6 and smaller than 1, and the n is larger than or equal to 0 and smaller than or equal to 0.3. A core and shell multi-layered compound structure is adopted, a core of the core and shell multi-layered compound structure is made of a high-nickel-based and high-specific-capacity multi-element material, a shell of the core and shell multi-layered compound structure is made of a high-safety material with the identical nickel and manganese molar content, wherein the high-safety material contains a small quantity of cobalt or does not contain the cobalt, a space between the core and the shell is made of a multi-layered material and is configured according to proportions different from those of the shell and proportions of the core, the proportions of core materials in the multi-layered material from inside to outside are gradually reduced while the proportions of shell materials in the multi-layered material from inside to outside are gradually increased, and accordingly the multi-stage core and shell structure is formed. The multi-stage core and shell structure multi-element material precursor not only has a high specific capacity performance of the core materials, but also has characteristics of high circulatory stability and safety of the shell materials, and is low in large-scale manufacturing cost. The cost is not increased as compared with a homogeneous multi-element material. Besides, repeatability is high, batch stability is good, and the multi-stage core and shell structure multi-element material precursor meets requirements of large-scale commercial application.

Description

technical field [0001] The invention belongs to the technical field of cathode materials for lithium ion batteries, and in particular relates to a cathode material for a high-capacity lithium ion battery and a precursor thereof, and a preparation method for the cathode material and the precursor thereof. Background technique [0002] Lithium-ion secondary batteries have the advantages of high specific energy, long cycle life and stable discharge performance, making them ideal power sources for various portable electronic products. The high-nickel lithium cobalt oxide (LNCO) has been widely researched around the world as a material with high specific capacity and high specific energy density. However, even if LNCO is doped with other elements, it cannot Ni in the surface layer of the material in the state 4+ and Co 4+ And NiO and the electrolyte will generate a large amount of heat and oxygen, which will reduce the cycle performance of the material and affect its safety per...

AI Technical Summary

Problems solved by technology

However, when preparing this kind of concentration gradient material, it was found that the preparation of the concentration gradient material precursor by this method requires high precision of the experimental equipment, and the content of Ni, Co, and Mn has been changing during the experiment, so it is difficult Three flow rates are precisely controlled at each moment, which leads to the fact that the ratio of the three elements

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