Anode materials for lithium ion battery and preparation methods thereof

Abstract

The invention provides anode materials for a lithium ion battery and preparation methods thereof. An anode material for the lithium ion battery is equipped with a core shell structure. A core of the core shell is formed by nano-silicon. A material for forming an outer shell of the core shell structure comprises graphene. Expansion space is set between the core and the outer shell. According to theanode material for the lithium ion battery provided by the invention, the expansion space is reserved for the nano-silicon core in the core shell structure, so Si is enabled to expand and retract fully in a charge / discharge process. In this way, outer shell fracture does not occur in anode material particles, si circulation service life of the anode material is extended. Conductivity is improvedthrough utilization of the graphene in the outer shell, so capacity of the anode material is relatively high.

Description

technical field [0001] The invention relates to the technical field of lithium-ion batteries, in particular, the invention relates to a negative electrode material of a lithium-ion battery and a preparation method thereof. Background technique [0002] At present, graphite (C) is the main anode material for lithium-ion batteries used in the market, and silicon (Si) has a high theoretical specific capacity (4200mAh / g) as an anode material for lithium-ion batteries. In order to improve the overall energy density of the battery , the development of silicon anode materials for lithium-ion batteries has become the focus of attention. [0003] However, the problem facing Si as the negative electrode material of lithium-ion batteries is that the volume expansion rate of silicon negative electrode materials can be as high as 300% during the charging and discharging process of the battery, resulting in the pulverization of silicon particles and the formation of a large number of soli...

AI Technical Summary

Problems solved by technology

[0003] However, the problem facing Si as the negative electrode material of lithium-ion batteries is that the volume expansion rate of silicon negative electrode materials can be as high as 300% during the charging and discharging process of the battery, resulting in the pulverization of silicon particles and the formation of a large number of solid electrolyte interface (SEI) films. , which consumes a large amount of electrolyte, making the conductivity of lithium-ion batteries worse and the capacity fading rapidly

[0004] At this stage, there are three methods to solve the problem of volume expansion: the first one is to use organic matter to coat and calcine Si nanoparticles to inhibit the expansion of silicon. No cracking; the second is to use organic matter to coat and calcinate silicon-magnesium (Si-Mg) alloy nanoparticles, and then use hydrofluoric acid (HF) to etch into carbon-coated porous nano-silicon particles, although this method The expansion volume is reserved for Si, which is conducive to the full use of the capacity of Si, but the cost of this method is high; the third method is to combine Si with graphene, carbon nanotubes and other high-conductivity materials to prepare high-conductivity Si-based composite materials, this method greatly improves the conductivity of the composite material, but it cannot protect the powdering and falling off of Si nanoparticles

[0005] Therefore, the current silicon anode materials still need to be improved.

Images