Lithium-rich manganese-based positive electrode material precursor, positive electrode material and preparation method thereof

Abstract

The invention belongs to the field of electrode material preparation and relates to a lithium-rich manganese-based cathode material precursor, a cathode material and a preparation method thereof. The preparation method comprises the following steps: mixing metal salts (manganese salt, cobalt salt and nickel salt) and a surfactant and water, and dissolving to obtain a metal salt solution; putting a precipitant in water, stirring and dissolving to obtain a precipitant solution; carrying out liquid-liquid coprecipitation reaction on the metal salt solution and the precipitant solution in a hypergravity field reactor, filtering, cleaning, and carrying out vacuum drying so as to obtain a precursor; mixing the precursor and lithium salt and then calcining so as to obtain the lithium-rich manganese-based cathode material. By the coprecipitation method based on the hypergravity technology, the lithium-rich manganese-based cathode material precursor with primary particle being below 100 nm and secondary particle being 1-10 microns is rapidly prepared, and furthermore the prepared cathode material has advantages of uniform component distribution and particle size distribution, small granularity and high activity. Initial irreversible capacity can be reduced, and cycle performance of a lithium ion secondary battery can be enhanced.

Description

technical field [0001] The invention belongs to the field of electrode material preparation, and in particular relates to a precursor of a lithium-rich manganese-based positive electrode material, a positive electrode material and a preparation method thereof. Background technique [0002] Lithium-rich manganese-based cathode material is a new type of cathode material successfully developed in recent years; it is essentially a layered compound Li[Li 1 / 3 mn 2 / 3 ]O 2 and LiMO 2 (M=Ni, Co, Mn) solid solution cathode material, its chemical formula can be written as xLi[Li 1 / 3 mn 2 / 3 ]O 2 ·(1-x)LiMO 2 . Compared with traditional lithium-ion battery cathode materials (such as lithium cobaltate, lithium iron phosphate, lithium manganate, etc.), this type of material has a higher working voltage platform (up to 4.8V or more), higher specific capacity ( Up to 300mAh / g), excellent high-temperature electrochemical performance, cheap price, abundant resources, etc., are graduall...

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Problems solved by technology

However, this method does not nano-process the material, so it is difficult to give full play to the real capacity of the material (Zhi Xiaoke, Liu Hongguang, Ye Xuehai, He Aizhen, Zhang Su, Shi Jie, Xu Yang, a lithium-rich manganese-based positive electrode material for lithium-ion batteries The preparation method of Chinese invention patent application, application number: 201210357169.3, application date: 2012-09-21, publication number: CN102881887A)

[0005] (2) Wu Feng, Chen Shi and others invented a method for preparing a lithium-rich manganese-based ternary composite positive electrode material. This method obtains a precursor by controlling co-precipitation. The particle size distribution of the obtained precursor material is uniform, and the material performance has been optimized, but the process conditions required by this method are complex, and it is difficult to achieve particle size control in industrial production (Wu Feng, Chen Shi, Zhong Yunxia, ​​Bai Ying, Wu Chuan, Bao Liying, Wu Borong, a rich Preparation method of lithium-manganese-based ternary composite cathode material, Chinese invention patent application, application number: 201210149592.4, application date: 2012-05-14, publication number: CN102655232A)

[0006] (3) Hou Hongjun, Li Shijiang and others invented a microspherical layered lithium-rich manganese-based solid solution cathode material and its preparation method. The method obtains a doped and spherical lithium-rich manganese solid solution material by doping, spray drying, etc. , the performance of the material is better, but the spray drying process used in this method is difficult to scale up, and it is also difficult to prepare spherical lithium-rich manganese solid solution materials in large quantities in industrial production (Hou Hongjun, Li Shijiang, Luo Guoguo, Luo Chuanjun, Yang Huachun, Li Yunfeng , Xue Xujin, Ding Yunling, Zhao Yongfeng, A microsphere layered lithium-rich manganese-based solid solution cathode material and its preparation method, Chinese invention patent application, application number: 201210435110.1, application date: 2012-11-02, publication number: CN102916176A)

[0010] (3) Huang Yunhui's research group first synthesized spherical MnCO 3 precursor, and then the MnCO 3 , LiOH and Ni(NO 3 ) 2 Mixed sintering to obtain a hollow spherical lithium-rich manganese material, the material has high specific capacity and rate performance, but more synthesis steps are used, and the sintering at high temperature requires maintaining the hollow spherical structure of the material, and the required process conditions are harsh ( Jiang Y, Yang Z, Luo W, Hu X, Huang Yunhui, Hollow 0.3Li2MnO3_0.7LiNi0.5Mn0.5O2microspheres as a high-performance cathode material forlithium–ion batteries, Phys.Chem.Chem.Phys.,2013,15,22954 —2960)

However, the nanoparticles prepared by this method will not self-assemble into micron particles, which is not suitable for the preparation of positive electrode materials for lithium-ion batteries.

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