A kind of preparation method of silicon carbon negative electrode material and lithium ion battery

Abstract

The invention discloses a preparation method of a silicon-carbon anode material and a lithium ion battery. The preparation method includes: mixing nano-silicon with graphite solid phase, sieving the mixture, mixing the mixture with an amorphous carbon precursor solid phase, sieving the mixture, performing vibrating shaping, and sintering the product to obtain the silicon-carbon anode material. Bymeans of sieving, the graphite, nano-silicon and amorphous carbon precursor are dispersed, so that the surface of graphite can be uniformly coated with the nano-silicon and the surface of nano-siliconcan be uniformly coated with the amorphous carbon precursor; through the vibrating shaping, surface-to-surface contact between the amorphous carbon precursor and the nano-silicon and between the nano-silicon and the graphite is achieved without existence of a gap; through the sintering step, a volatile substance can be slowly volatilized from interior to exterior, so that a problem of forming pores since a huge gas pressure is generated from the volatile substance can be avoided. The silicon-carbon anode material, when being used for producing the lithium ion battery, shows excellent electrochemical cyclic stability.

Description

technical field [0001] The invention relates to the technical field of lithium-ion batteries, in particular to a method for preparing a silicon-carbon negative electrode material and a lithium-ion battery. Background technique [0002] In recent years, with the increase in the demand for new energy electric vehicle cruising range, the current commercial graphite anode material (theoretical specific capacity is 372mAh / g) has been difficult to meet the current demand, and it is urgent to develop a high specific capacity anode material. Elemental silicon is most likely to replace commercial graphite anode materials due to its high theoretical specific capacity (4200mAh / g) and low lithium intercalation potential, but elemental silicon will produce a huge volume effect ( up to 300%), leading to the collapse of the electrode structure and the peeling off of the electrode material, resulting in the separation between the electrode materials, the electrode material and the conductiv...

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Problems solved by technology

[0003] Chinese patent CN102651476B discloses a silicon-carbon composite negative electrode material and its preparation method. The silicon-carbon composite negative electrode material uses graphite as the core and nano-silicon as the shell, and is prepared by the charge adsorption method of positive and negative ion surfactants in the solution. , although this method can achieve uniform dispersion of nano-silicon on the graphite surface, but there is no amorphous carbon layer to cover nano-silicon, which will lead to huge volume expansion and structural collapse of nano-silicon during the process of delithiation and intercalation, resulting in poor cycle performance. poor

[0004] For example, Hou X et al. (Journal of Power Sources, 2014, 248(2): 721-728) disclose a graphite-based nano-Si uniformly dispersed on the graphite surface, and amorphous carbon as a shell coated nano-Si The silicon-carbon composite material on the surface, although the obtained silicon-carbon material has excellent cycle performance, but this method uses multiple spray drying processes, the steps are complicated, the reaction process is difficult to control, and the stability is poor, which is not conducive to industrial development and application

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