Lithium nickel cobalt composite oxide cathode material

Abstract

A lithium nickel cobalt composite oxide cathode material includes a plurality of secondary particles. Each secondary particle consists of aggregates of fine primary particles. Each secondary particle includes lithium nickel cobalt composite oxide, which is expressed as LiaNi1-bCobO2. An average chemical formula of each secondary particle satisfies one condition of a is not less than 0.9 and not more than 1.2, b is not less than 0.1 and not more than 0.5. The lithium nickel cobalt composite oxide has a structure with different chemical compositions of primary particles from the surface toward core of each of the secondary particles. The primary particle with rich Co content near the surface and the primary particle with rich Ni content in the core of secondary particle of the lithium nickel cobalt composite oxide cathode material have provided the advantages of high safety and high capacity.

Description

technical field [0001] The invention relates to a lithium-nickel-cobalt positive electrode material powder, and more specifically, to a lithium-nickel-cobalt oxide having different stoichiometric dosage ratios from the surface nanoparticles of the powder particles to the core nanoparticles of the powder particles. Background technique [0002] Due to the vigorous development of 3C technology and the rising awareness of environmental protection, electric vehicles are becoming more and more important; however, no matter what kind of battery application system, its main demand goal is still to pursue lithium-ion batteries with high energy density, and its volumetric energy density requirements have already More than 400Wh / L, while the volumetric energy density of lithium batteries in the current lithium-cobalt cathode material system is only 320-350Wh / L, and there is no room for performance improvement, so lithium-nickel cathodes with high energy density, low cost and non-toxici...

AI Technical Summary

Problems solved by technology

In order to improve the problem of lithium-nickel cathode materials, some scholars have incorporated cobalt ions with a relatively stable structure into lithium-nickel oxides to replace part of the nickel ions to synthesize lithium-nickel-cobalt cathode materials, thereby improving the structural stability and Thermal stability, and the higher the content of cobalt doped in the material, the better the safety of the material, but the capacity will decrease, and the original goal of pursuing a lithium-ion battery with high energy density will be lost

[0003] At present, there are not a large number of commercial lithium-nickel-cobalt cathode materials in the world. The main key is that the safety issue has not been resolved. In order to solve this problem, some research institutes or material manufacturers will choose to implant other metal ions into lithium-nickel-cobalt In the structure of the material, the stability of the material structure is increased. Although the structure will be more stable than the pure lithium nickel cobalt material, the safety will be improved, but the capacitance will be significantly reduced due to the increase in the internal resistance of the material.

[0004] In recent years, some scholars have modified the surface of lithium-nickel-cobalt cathode materials with a nano-scale protective layer to avoid the reaction between the material and the electrolyte, resulting in structural collapse. Although this method can reduce the heat release of the material, it cannot improve the heat release. temperature, and the mass production of materials and coating technology are not easy to operate

[0005] At present, some scholars are also studying lithium nickel cobalt oxide as the core of the positive electrode material, and then covering the surface of the material with a more thermally stable positive electrode material as a protective shell, such as lithium nickel cobalt manganese oxide or lithium nickel manganese oxide. The thickness of the protective shell layer is about 1-2 μm, forming a composite positive electrode material with a core-shell structure. Although this structure can effectively improve the safety of the material, it may also cause an increase in the internal interface impedance of the material, making the material in a large current. The efficiency of discharge is reduced, and the synthesis quality of materials with this structure in mass production is not easy to grasp

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