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Silicon carbon composite material and preparation method thereof, lithium ion battery containing same

A silicon-carbon composite material, composite material technology, applied in nanotechnology for materials and surface science, battery electrodes, secondary batteries, etc. The effect of lithium storage capacity characteristics, easy control of oxidation degree, specific capacity and cycle performance

Inactive Publication Date: 2012-11-28
CHERY AUTOMOBILE CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] Although the above methods alleviate the capacity fading of silicon-based negative electrode materials to a certain extent, the mechanism is simple physical compounding or high-temperature carbon coating, which cannot fundamentally suppress the volume effect in the process of charging and discharging. After cycling, the capacity will start to decay rapidly again

Method used

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  • Silicon carbon composite material and preparation method thereof, lithium ion battery containing same
  • Silicon carbon composite material and preparation method thereof, lithium ion battery containing same
  • Silicon carbon composite material and preparation method thereof, lithium ion battery containing same

Examples

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Embodiment 1

[0030] This embodiment provides a method for preparing a silicon-carbon composite material, comprising the following steps:

[0031] (1) Weigh a certain amount of silicon powder with a particle size of 5 μm, heat it up to 480°C at a rate of 7°C / min in an air atmosphere in a muffle furnace, and burn it for 1.2 hours to obtain a composite of silica-coated silicon. Material 4.

[0032] (2) Put the silica-coated silicon composite material 4 in the center of the tube furnace, evacuate the tube furnace until the pressure in the furnace is less than or equal to 0.01 atmosphere, and then raise the temperature to 500 °C at a rate of 7 °C / min At this time, a mixed gas of argon and acetylene (wherein the volume ratio of argon and acetylene is 9:1) was introduced, and then the temperature of the furnace was increased by 50°C and kept for 100 minutes. The carbon layer 3 coated on the silicon dioxide-coated silicon composite material 4 by the chemical vapor deposition method is uniform, an...

Embodiment 2

[0040] This embodiment provides a method for preparing a silicon-carbon composite material, comprising the following steps:

[0041] (1) Weigh 1,000 grams of silicon powder with a particle size of 5 μm, heat it up to 500°C at a rate of 7°C / min in an air atmosphere in a muffle furnace, and burn it for 1.5 hours to obtain a composite of silica-coated silicon. Material.

[0042] (2) Mix the silica-coated silicon composite material with 80 grams of phenolic resin by ball milling, and burn at 700° C. for 3 hours under an inert atmosphere.

[0043] (3) Corroding the silicon dioxide with an excess of hydrofluoric acid with a concentration of 7wt%, to obtain a carbon content of 9wt% in the silicon-carbon composite material.

[0044] The manufacturing method of the CR2025 button battery is as in Example 1. The battery manufactured according to the method of this embodiment has a specific discharge capacity of 1232mAh / g for the first time, and remains at 833mAh / g after 105 cycles.

Embodiment 3

[0046] This embodiment provides a method for preparing a silicon-carbon composite material, comprising the following steps:

[0047] (1) Weigh a certain amount of silicon powder with a particle size of 30nm, heat it up to 550°C at a rate of 8°C / min in an air atmosphere in a muffle furnace, and burn it for 2 hours to obtain a composite of silica-coated silicon. Material.

[0048] (2) Put the silicon dioxide-coated silicon composite material in the center of the tube furnace, evacuate the tube furnace until the pressure in the furnace is less than or equal to 0.01 atmosphere, and at this time, pass the mixed gas of argon and acetylene (wherein , the volume ratio of argon and acetylene is 9:1), and then the temperature is raised to 700°C at a rate of 8°C / min and kept for 50 minutes.

[0049] (3) Corroding the silicon dioxide with excess hydrofluoric acid with a concentration of 8wt%, to obtain a carbon content of 7wt% in the silicon-carbon composite material.

[0050] The manuf...

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Abstract

The invention discloses a silicon carbon composite material and a preparation method thereof, and a lithium ion battery containing the material. The preparation method of the silicon carbon composite material comprises the following steps: (1) calcining silicon powder in oxygen-containing atmosphere to obtain a composite material with silica-coated silicon; (2) coating the composite material with silica-coated silicon by carbon; (3) corroding the silica with excessive hydrofluoric acid to obtain the silicon carbon composite material. The preparation process of the silicon carbon composite material is simple; the preparation of the composite material with silica-coated silicon by partial oxidation of silicon is simple, and controllable in silicon oxidation degree; the silica layer of the material obtained after coating the composite material with silica-coated silicon by carbon is easy to remove; and a core shell structure with a certain gap between the carbon layer and the silicon is obtained. The preparation process is simple; the silicon carbon composite material prepared by the preparation method has better electrochemical properties; batteries prepared by the silicon carbon composite material have better cycle performance.

Description

technical field [0001] The invention belongs to the technical field of battery manufacturing, and in particular relates to a silicon-carbon composite material with high specific capacity, a preparation method thereof, and a lithium-ion battery prepared by using the silicon-carbon composite material. Background technique [0002] At present, practical lithium-ion batteries mainly use graphitized carbon as the negative electrode material. The large layered structure of graphite-based negative electrode materials provides a place for lithium storage. The large layered structure determines the low theoretical specific capacity of the material. (about 372mAh / g) characteristics. Therefore, high-capacity and high-rate anode materials have high research and application value. For a long time, silicon-based and tin-based materials have become research hotspots due to their high mass specific capacities (theoretical specific capacities of silicon and tin are 4200mAh / g and 990mAh / g, r...

Claims

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Application Information

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IPC IPC(8): H01M4/38H01M10/0525B82Y30/00B82Y40/00
CPCY02E60/122Y02E60/10
Inventor 朱广燕刘云建赵志刚陈效华
Owner CHERY AUTOMOBILE CO LTD
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