Preparation method of monocrystal-like lithium nickel cobalt manganate

Abstract

The invention provides a preparation method of monocrystal-like lithium nickel cobalt manganate, which comprises the following steps: 1. preparing a transition metal salt solution, adding a complexingagent or preparing a complexing agent solution, and preparing a pH regulating solution; 2, preparing a nickel-cobalt-manganese metal precipitate; continuously pumping various solutions prepared in the first step into a reaction kettle at the same time through different feeding pipes; connecting a reactor filled with manganese salt with a feed port of a reaction kettle, introducing protective gas,heating, continuously adding an oxidant into the reactor, reacting, adjusting the flow of the protective gas, introducing manganese oxide generated by the reaction into the reaction kettle, controlling the pH value in the reaction kettle, and carrying out precipitation reaction to obtain nickel-cobalt-manganese metal precipitates after the reaction is finished; 3, pre-sintering to prepare a nickel-cobalt-manganese precursor; and 4, performing lithiation sintering, such that the monocrystal-like lithium nickel cobalt manganate positive electrode material is obtained.

Description

technical field [0001] The invention relates to the technical field of positive electrode materials for lithium ion batteries, and in particular, relates to a preparation method of quasi-single crystal nickel-cobalt lithium manganate. Background technique [0002] At present, the industrialized cathode materials are mainly LiCoO 2 , LiFePO 4 , Li 2 MnO 4 and ternary cathode materials. Among them, the nickel-cobalt-manganese ternary material is one of the hotspots in the research of a new generation of lithium-ion ternary cathode materials. However, at present, the ternary cathode materials produced by domestic and foreign manufacturers are secondary spherical particles formed by agglomeration of fine crystal grains (that is, primary particles), which have the following disadvantages: 1. There are voids inside the particles, which reduces the compaction density; 2. The particles If the size is too large, the structure is unstable and cannot withstand pressure, and it is ...

AI Technical Summary

Problems solved by technology

However, at present, the ternary cathode materials produced by domestic and foreign manufacturers are secondary spherical particles agglomerated by fine grains (that is, primary particles), which have the following disadvantages: 1. There are voids inside the particles, which reduces the compaction density; 2. The particles The size is too large, the structure is unstable and not pressure-resistant, and it is easy to break, resulting in poor circulation; 3. The particle grows disorderly inside, and the rate performance of the material is low

[0005] First: The small particle size has strict requirements on the reaction conditions in the synthesis process. If the particle size is too small, the specific surface area will be larger, resulting in the agglomeration of the precursor particles, resulting in an increase in internal voids due to poor sphericity, and the subsequent calcination process will cause the finished product to be too large. Too wide, and the growth time of small particle size is relatively short, and the crystallinity and order of the precursor are poor

[0006] Second: Due to the large specific surface area of ​​the small-particle precursor prepared by conventional methods, its surface energy is greater than that of the large-particle precursor, so agglomeration will occur before sintering, and the particles of the agglomerated precursor will appear spliced ​​after sintering appearance, and due to the enlarged particle size distribution due to agglomeration, in the subsequent process such as coating, there will be coating dead ends, and the particle consistency is poor

And because the particle strength of the particles produced after agglomeration is not as high as that of the precursor particles grown in situ, it will be crushed in the subsequent application process of preparing the battery, such as in the rolling step, exposing the non-coated interface, which is not coated The surface of the coated particles will have a side reaction with the electrolyte, which will cause serious consequences such as battery bulging, which greatly reduces the cycle stability of the material

[0007] Third: The growth time of small particles synthesized by conventional methods is shorter than that of large particles, and the crystalline order of the crystal structure of small particles is weaker than that of large particles. When the crystallinity of the precursor is low, the positive electrode material produced after high temperature lithiation There will also be corresponding inheritance, and the generation of impurity phases may cause the deterioration of the electrical properties of the material, which will affect the performance of the material

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