Preparation method of spherical NCM811 positive electrode material with surface large-particle accumulation structure

Abstract

The invention provides a preparation method of a spherical NCM811 positive electrode material with a surface large-particle accumulation structure, which comprises the following steps: preparing a precursor Ni0.8Co0.1Mn0.1(OH)2, preparing a positive electrode material Ni0.8Co0.1Mn0.1(OH)2 and assembling a battery. According to the invention the 10 [mu]m grade spherical particles with the surface large-particle accumulation structure are prepared by controlling reaction condition parameters. The method is simple and controllable in operation and low in cost, has the potential of realizing industrialization, and provides guiding significance for preparing the ternary material single crystal precursor by a coprecipitation method.

Description

technical field [0001] The invention relates to the field of positive electrode materials for lithium batteries, in particular to a method for preparing a spherical NCM811 positive electrode material with a surface large particle stacking structure. Background technique [0002] (1) Hua et al. synthesized NCM811 electrode material with traditional spherical morphology by co-precipitation method [Journal of Alloys and Compounds, 614 (2014): 264–270]. The material shows a good crystal structure. Under the condition of 1C and 4.3V, the discharge specific capacity in the first cycle shows a high capacity close to 185mAh / g; however, after 100 cycles, its capacity decreases to below 150mAh / g, showing poor cycle stability. Although after improvement, the synthesized full concentration gradient material shows a decreasing concentration gradient of Ni from the inner core to the outer shell, showing good cycle stability and rate performance; however, its relatively cumbersome process...

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Problems solved by technology

①Spherical ternary materials prepared by traditional technology, in the process of charging and discharging, due to the anisotropic volume change, the generation and propagation of microcracks inside the particles will be caused, the spherical particles will be broken, and the electrolyte will penetrate into the interior to aggravate the occurrence of side reactions, resulting in cycle Poor performance and rate performance; ②Post-processing such as doping and coating, the preparation process is relatively troublesome, while increasing the process flow and consuming more costs, the side effects of the introduced doping and coating ions on the system Careful research is still needed; and this method cannot essentially solve problems such as poor cycle stability; ③Although single crystal materials can well solve microcracks caused by anisotropic volume changes and improve the structural integrity of materials; but the existing There are still many shortcomings in the process of preparing single crystals by solid phase method and molten salt method. For example, the molten salt method consumes excessive lithium source and molten salt, which increases the cost and causes waste of resources. In addition, the washing process is not only time-consuming, but also affects the later materials. The high-temperature sintering of the solid-state method will accelerate the volatilization of lithium sources, which will aggravate the mixing of lithium and nickel, etc.; ④ In addition to the solid-phase method and molten salt method, the synthesis of single crystal materials has always been a difficult point in current research. The process of synthesizing single crystal precursors by co-precipitation is still in the exploratory stage

However, the current main methods, such as solid-phase method and molten salt method, have problems such as excessive consumption of lithium source and molten salt, increased cost and waste of resources, and serious mixed discharge of lithium and nickel.

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