Nano silicon composite material of core-shell structure as well as preparation method and application of material

Abstract

The invention relates to the technical field of battery negative electrode materials, in particular to a core-shell nano-silicon composite material as well as a preparation method and application thereof. The composite material comprises an inner core and an outer shell wrapping the surface of the inner core, the inner core is of a porous structure formed by bonding nanometer silicon and an electronic conductor material together through a bonding agent, and the outer shell is a conductive polymer layer or a composite layer formed by a conductive polymer and a carbon material. The nano siliconcomposite material prepared by the invention has a core-shell structure; the inner core also has a porous structure; the conductive performance of silicon particles is ensured by the inner core consisting of the nano silicon and the conductive material, side reaction between the silicon and the outside in the mixing process can be effectively solved by the polymer layer or the shell formed by thepolymer and conductive agent composite layer, direct contact between the silicon and the electrolyte is maintained, and the cycling stability of the battery is improved. In addition, the conductive polymer in the outermost layer can improve the conductivity of the whole particles, and the cycle efficiency of the battery is greatly improved.

Description

technical field [0001] The invention relates to the technical field of negative electrode materials for batteries, in particular to a nano-silicon composite material with a core-shell structure and a preparation method and application thereof. Background technique [0002] The information disclosed in this background section is only intended to increase the understanding of the general background of the present invention, and is not necessarily taken as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to those skilled in the art. [0003] The volume of the silicon negative electrode material changes greatly during the charging and discharging process, which makes it easy to pulverize and fall off from the current collector, making it difficult to form a stable SEI film, and the fresh interface of silicon after lithium intercalation contacts with the electrolyte will be reduced, consuming activity Lithium, these factors ...

AI Technical Summary

Problems solved by technology

[0006] Aiming at the problems of shedding and low cycle efficiency caused by the product expansion / shrinkage of the silicon negative electrode during charge and discharge, the present invention provides a core-shell nano-silicon composite material and its preparation method and application. Space is needed, which can effectively eliminate the negative impact of volume effect on battery cycle. The use of polymer-wrapped nano-silicon can avoid direct contact between silicon and water, effectively reduce the occurrence of side reactions, and prevent the peeling of active materials caused by the volume expansion of silicon. , so as to effectively improve the cycle stability of the battery. Internal doping and external coating of carbon materials can improve the conductivity of the negative electrode material and greatly improve the cycle efficiency of the battery.

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