Preparation method of composite conductive agent coated monocrystal-like lithium-rich manganese-based positive electrode material

Abstract

The invention discloses a preparation method of a composite conductive agent coated monocrystal-like lithium-rich manganese-based positive electrode material. The preparation method comprises the following steps: (1) regulating the Zeta potential of a multi-component composite conductive agent solution, so that the charge of the multi-component composite conductive agent solution is opposite to the charge of the monocrystal-like lithium-rich manganese-based positive electrode material solution, wherein the multi-component composite conductive agent solution is a mixed solution of graphene, carbon nanotubes and conductive carbon black; and (2) carrying out ultrasonic dispersion on the multi-component composite conductive agent solution, and then carrying out stirring dispersion, filtering,washing, drying and sintering on the multi-component composite conductive agent solution and the monocrystal-like lithium-rich manganese-based positive electrode material solution to obtain the composite conductive agent-coated monocrystal-like lithium-rich manganese-based positive electrode material. According to the invention, matrix materiasl and the graphene sheets, and the carbon nanotubes and the conductive carbon black are intertwined to form a 'point-line-surface' three-dimensional porous network structure, so that the capacity, the cycle performance and the rate capability of the material are remarkably improved.

Description

technical field [0001] The invention belongs to the field of battery materials, and in particular relates to a method for preparing a single-crystal lithium-rich manganese-based cathode material coated with a multi-component composite conductive agent. Background technique [0002] At present, the research and development of cathode materials for lithium-ion batteries is lagging behind, which has become one of the factors restricting the further development of the lithium battery industry. In recent years, the state has proposed that the specific energy of power batteries will reach 350Wh / kg by 2020, so the demand for new high-capacity cathode materials for lithium-ion power batteries is more urgent. [0003] Compared with traditional cathode materials, lithium-rich manganese-based layered cathode materials Li[Li 1-x-y-z Ni x co y mn z ]O 2 Lower cost, more environmentally friendly, has a charging mechanism different from traditional cathode materials, the charging volt...

AI Technical Summary

Problems solved by technology

However, if the degree of single crystallization of the lithium-rich manganese-based cathode material is too high, such as the material is mainly composed of large single crystals with a diameter of about 10 microns, due to the low electrical conductivity and ionic density of the lithium-rich manganese-based cathode material, Mobility and other shortcomings will inevitably lead to worse rate performance than materials with secondary spherical particle morphology

In addition, when preparing lithium-rich manganese-based cathode materials in the industry, it is necessary to strictly control the content of fine powders with irregular shapes and particle sizes less than 0.5 microns in the finished product. security risks

[0005] In addition, during the charge and discharge process of lithium-rich manganese-based cathode materials, the HF generated in the electrolyte will also corrode the structure of the cathode material, resulting in a decrease in the structural stability of the material. At the same time, because the cathode material is charged to a high voltage (>4.5V) will come out of Li 2 O, may cause cations to occupy oxygen vacancies or Li sites, thereby reducing the order degree of its layered structure, easily leading to structural collapse, and making the positive electrode material have lower cycle performance during charge and discharge.

[0006] The above shortcomings have also become the main factors that limit the further application of lithium-rich manganese-based cathode materials.

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