Preparation method of high-capacity silicon-based negative electrode material of lithium-ion battery

Abstract

The invention discloses a preparation method of a high-capacity silicon-based negative electrode material of a lithium-ion battery. The method comprises the preparation processes of: mixing nano silicon, graphite and a pyrolytic carbon organic matter precursor to obtain composite material precursor slurry; and carrying out spray drying to obtain precursor powder; and finally carrying out roasting treatment in an inert atmosphere and then carrying out grinding to obtain an organic matter pyrolytic carbon-coated nano silicon / graphite composite material. According to the preparation method, the dispersity of the nano silicon in the silicon-carbon negative electrode material can be improved; the structure stability of the material in a lithium intercalation and deintercalation process is improved; the condition that the material has relatively high conductivity is ensured; a pyrolytic carbon coating layer effectively coats the surfaces of material particles; the interface characteristic of the material can be effectively improved; and the electrochemical properties of the silicon-carbon negative electrode material are improved.

Description

Technical field [0001] The invention relates to the technical field of lithium ion battery negative electrode materials, in particular to a method for preparing silicon-based negative electrode materials for high-capacity lithium ion batteries. Background technique [0002] Lithium-ion secondary batteries have now become the mainstream chemical power source and are widely used in most mobile terminal devices. Compared with nickel-metal hydride, nickel-cadmium and lead-acid batteries, lithium-ion secondary batteries have high working voltage, high specific energy and The advantages such as long cycle life have been developed rapidly in recent years, and the applications in mobile devices such as notebook computers, digital cameras, mobile phones, MP3 and MP4 have become more and more extensive. With the development of mobile devices in the direction of miniaturization and multi-function, higher requirements are put forward for the energy density and service life of lithium ion sec...

AI Technical Summary

Problems solved by technology

Li and Si will form a LixSi ( 03.7 Si 5 Phase, the capacity is as high as 3572mAh / g, which is much larger than the theoretical capacity of graphite, but during the charge and discharge process, silicon will undergo a huge volume change, resulting in material pulverization, peeling, loss of electrical contact, and rapid capacity decay

In the prior art, the cycle stability and initial charge and discharge of silicon-based negative electrodes have been improved to a certain extent by reducing the particle size of silicon materials, making silicon porous materials, reducing the dimensions of silicon materials, and preparing silicon-carbon composite materials. Efficiency, however, most of these improvement measures require high cost, and the corresponding electrolyte needs to be matched to better perform its performance, and the long-term cycle performance of the material is still poor

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