A kind of silicon oxide carbon composite negative electrode material, its preparation method and lithium ion battery

Abstract

The invention provides a silicon oxide-carbon composite negative electrode material and a preparation method thereof and a lithium-ion battery. The preparation method comprises the following steps of(a) heating silicon oxide to first temperature in inert atmosphere, adjusting the flow velocity of an inert gas and carrying out heat preservation to obtain a silicon oxide composite material connected with a silicon nanowire, wherein the first temperature is 800-1300 DEG C and the flow velocity of the inert gas is 0-800sccm; and (b) adjusting the silicon oxide composite material, obtained in thestep (a), connected with the silicon nanowire to second temperature, introducing a carbon source gas for chemical vapor deposition under the condition of introducing the inert gas, cooling and then obtaining the silicon oxide-carbon composite negative electrode material, wherein the second temperature is 600-1,000 DEG C. The silicon oxide-carbon composite negative electrode material connected withthe silicon nanowire is obtained by adopting a preparation technology of combining in-situ growth of the silicon nanowire with carbon coating; the electron island effect of a silicon oxide-based material in a charge-discharge cycle process is effectively relieved through building a three-dimensional conductive network; and the silicon oxide-carbon composite negative electrode material has excellent electrochemical properties.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, and more specifically relates to a silicon oxide carbon composite negative electrode material, a preparation method thereof and a lithium ion battery. Background technique [0002] With the widespread use of various mobile electronic devices, such as smartphones, laptops, etc., lithium-ion batteries have thus received extensive attention. However, the energy density and power density of commercial lithium-ion batteries are difficult to meet the requirements of energy storage devices for technological development. Therefore, it is imminent to develop high-capacity electrode materials. [0003] Compared with the current commercially used carbon-based anode materials, silicon oxide-based anode materials show obvious advantages, such as high specific capacity, low lithium intercalation potential, stable cycle and rich content, so silicon oxide-based anode materials are considered It i...

AI Technical Summary

Problems solved by technology

However, there are some problems with the pure silicon oxide material as the negative electrode material of lithium-ion batteries. On the one hand, its inherent poor electrical conductivity limits its large-scale use; on the other hand, its electron loss due to volume expansion also makes it Capacity fading during cycling, specifically: the volume expansion effect (200%) of silicon oxide-based negative electrode materials in the process of charging and discharging can easily cause its capacity fading, and one of the most important points is the activity due to volume expansion-contraction. The island effect of the active material caused by the loss of electronic contact between the material particles. Once the active material loses the electronic contact, it will no longer be able to extract / intercalate lithium, which will eventually lead to the capacity decay of the material.

[0004] At present, in view of the poor conductivity of silicon oxide-based negative electrode materials and the capacity attenuation caused by the loss of contact between the active material particles caused by volume changes, researchers have proposed to use one-dimensional nanomaterials to construct three-dimensional conductive networks, such as carbon nanotubes and carbon nanotubes. Physical mixing of silicon oxide materials[Facile Synthesis and High AnodePerformance of Carbon FiberInterwoven Amorphous Nano-SiO x / Graphene for Rechargeable Lithium Batteries, ACS Appl.Mater.Interfaces 2013,5,11234]; but this simple physical mixing method cannot combine silicon oxide particles with one-dimensional nanomaterials, and it is still easy to cause Phenomenon in which electrons of active materials lose contact

Another example is that Yoo et al. used metal platinum to catalyze and synthesized a silicon-based anode material with a sea urchin-like structure in the process of high-temperature heat treatment, in which nanowires with a silicon / silicon oxide core-shell structure grow and protrude on the surface of micron-scale silicon particles, and interact with each other. A three-dimensional network [Helical Silicon / Silicon Oxide CoreShell Anodes Grown onto the Surface of BulkSilicon, Nano Letters, 2011, 11, 4324]; however, the preparation process of this method is complicated, and it needs to be catalyzed by precious metals such as platinum, and the preparation cost is high and difficult to realize. actual production application

The prior art also discloses the direct preparation of one-dimensional silicon nanomaterials as negative electrode materials [Self-sacrificed synthesis of carbon-coated SiO x nanowires for high capacity lithiumion batteries, J.Mater.Chem.A,2017,5,4183]; however, this method is mainly catalyzed by noble metals, the preparation process is complicated, the cost is high, and it cannot be used in practical industries, and silicon nanowires are prepared The tap density of the electrode is low, which seriously affects its volumetric energy density in practical applications

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