A core-shell type high voltage single crystal nickel cobalt lithium manganese oxide positive electrode material and its preparation method and application

Abstract

The invention discloses a core-shell type high-voltage single-crystal nickel-cobalt lithium manganate positive electrode material and its preparation method and application, comprising a core layer and a shell layer arranged on the outer surface of the core layer, both of which form a core-shell structure; the core layer The material is: Li a (Ni x co y mn 1‑x‑y )O 2 , 1.0≤a≤1.15, 0.2≤x≤0.6, 0.1≤y≤0.5, 1-x-y>0, the material of the core layer is a single crystal; the material of the shell layer is: Li b co k m 1‑ k o 2 , 0.9≤b≤1.05, 0.8≤k≤0.99, M is selected from one or more of Mg, Al, Zr, Ti and W; preparation: first prepare single crystal nickel cobalt lithium manganese oxide, and then prepare nano-cobalt trioxide slurry The material is made by adding single crystal nickel-cobalt lithium manganese oxide, lithium salt, and M-containing additives into the aforementioned slurry, spraying and drying after mixing, and sintering in an air atmosphere; and its application in lithium-ion batteries; the present invention It has excellent first-time charge and discharge efficiency and high capacity retention rate, and can also exert excellent cycle performance and safety performance at high voltages of 4.35V and 4.4V.

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-voltage single-crystal nickel-cobalt lithium manganese oxide 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 mater...

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Problems solved by technology

[0003] At present, the ternary positive electrode material of NCM is mainly secondary spherical particle structure. However, the above-mentioned traditional secondary spherical particle structure still has the following problems: 1. The mechanical strength of the particle structure is poor, and it is easy to cause secondary spherical particles during the compaction process. Broken; 2. There are many internal gaps and obvious structural defects. The unit pole piece is easily broken during the rolling process, which causes the battery capacity to attenuate in the later stage, and the compaction density is greatly limited. At the same time, it also increases the difficulty of processing and limits the energy density. 3. The internal pores are large and difficult to cover. The active material is in contact with the electrolyte, and it will be corroded by HF under high temperature conditions, destroying the interface structure, and causing the dissolution of transition metals Ni, Co, and Mn in the electrolyte. Contact with the electrolyte leads to increased side reactions, a large amount of gas is generated, the air pressure of the cell increases, and the battery expands, causing serious safety hazards; 4. There are many surface defects on the particles, and side reactions are prone to occur

However, studies have shown that single crystal nickel-cobalt-manganese ternary cathode materials still have problems such as low initial charge and discharge efficiency, serious capacity loss, and cycle performance under high voltage (≥4.35V) needs to be further improved.

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