Core-shell high-nickel monocrystal nickel cobalt lithium manganate positive electrode material and preparation method and application thereof

Abstract

The invention discloses a core-shell high-nickel monocrystal nickel cobalt lithium manganate positive electrode material and a preparation method and application thereof, and the positive electrode material comprises a core layer and a shell layer arranged on the outer surface of the core layer, wherein the core layer and the shell layer form a core-shell structure. The material of the core layeris Lia(NixCoyMn<1-x-y>)O2, wherein 1.0 <= a <= 1.15, 0.6 < x <= 0.95, 0.01 <= y <= 0.2, 1-x-y > 0, and the material of the core layer is of a monocrystal type; the material of the shell layer is Lib(NiiCojMnkM<1-i-j-k>)O2, wherein 0.9 <= b <= 1.05, 0.2 <= i <= 05, 0.15 <= j <= 0.5, 0.15 <= k <= 0.5, 1-i-j-k > 0, and M is one or more of Mg, Al, Zr, Ti and W. The preparation method comprises the following steps: firstly preparing high-nickel monocrystal lithium nickel cobalt manganate, then preparing nano lithium nickel cobalt manganate slurry, adding the high-nickel monocrystal lithium nickel cobalt manganate and an M-containing additive into the slurry, performing mixing, carrying out spray drying, and performing sintering in an oxygen atmosphere to prepare the lithium nickel cobalt manganate positive electrode material. The invention also discloses an application of the positive electrode material in lithium ion batteries. The positive electrode material has excellent first charge-discharge efficiency and high capacity retention rate, and also has excellent cycle performance and safety performance at a high temperature.

Description

technical field [0001] The invention belongs to the field of lithium-ion battery electrode materials, and relates to a positive electrode material, in particular to a core-shell type high-nickel single crystal nickel-cobalt lithium manganate positive electrode material and a preparation method and application thereof. Background technique [0002] Nickel cobalt lithium manganese oxide (NCM) ternary cathode material has been extensively studied since it was first reported in 1999. The ternary cathode material combines lithium cobaltate, lithium nickelate, The advantages of the three materials of lithium manganese oxide: it has the characteristics of high capacity of lithium nickel oxide, the high safety performance and low cost of lithium manganate oxide, and the good cycle performance of lithium cobalt oxide. It has become the most rapidly developed cathode material for lithium ion batteries in recent years. . [0003] At present, the ternary positive electrode material of ...

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Problems solved by technology

[0003]At present, the ternary cathode material of NCM is mainly secondary spherical particle structure, but the above-mentioned traditional secondary spherical particle structure still has the following problems: 1. Particle structure mechanical The strength is poor, and it is easy to cause secondary ball breakage during the compaction process of the pole piece; 2. There are many internal gaps and obvious structural defects, and the unit pole piece is prone to breakage during the rolling process, resulting in attenuation of battery capacity in the later stage, and the compaction density is affected. It greatly restricts the processing difficulty and limits the increase of energy density; 3. Due to the large internal pores, it is difficult to cover, and the active material material is in contact with the electrolyte, which will be corroded by HF under high temperature conditions, destroying the interface structure, This leads to the dissolution of transition metals Ni, Co, and Mn in the electrolyte, and the contact with the electrolyte leads to an increase in side reactions, a large amount of gas is generated, the air pressure of the cell increases, and the battery expands, causing serious safety hazards; Many, prone to side effects

However, studies have shown that single crystal high-nickel-cobalt-manganese ternary cathode materials still have problems such as low initial charge-discharge efficiency, serious capacity loss, high-temperature cycle and safety performance that need to be further improved.

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