A kind of nano-silicon composite material with core-shell structure and its preparation method and application

Abstract

The invention relates to the technical field of battery negative electrode materials, in particular to a core-shell nano-silicon composite material and a preparation method and application thereof. The composite material includes an inner core and a shell coated on the surface of the inner core, wherein the inner core is a porous structure in which nano-silicon and electronic conductor materials are bonded together by an adhesive, and the outer shell is a conductive polymer layer or a conductive Composite layer formed of polymer and carbon material. The nano-silicon composite material prepared by the present invention not only has a core-shell structure, but also has a porous structure in its inner core, wherein the inner core composed of nano-silicon and conductive materials ensures the conductivity of silicon particles, and the polymer layer or polymer and conductive agent The shell formed by the composite layer can effectively solve the side reaction between silicon and the outside world during the mixing process, and maintain the direct contact between silicon and electrolyte, improving the cycle stability of the battery. In addition, the conductive polymer on the outermost layer can improve the conductivity of the overall particle and greatly improve the cycle efficiency of the battery.

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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