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Preparation method of silicon-carbon-graphite composite anode material

A negative electrode material, graphite technology, applied in the field of functional materials, can solve the problems of high reduction temperature, high energy consumption, and many by-products, and achieve the effect of low preparation temperature, low energy consumption, and low equipment requirements

Inactive Publication Date: 2016-06-01
HUNAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

This method has a high reduction temperature (above 2000°C), high energy consumption, many by-products and the obtained silicon particle size is micron, which is not suitable for lithium-ion battery negative electrode materials

Method used

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  • Preparation method of silicon-carbon-graphite composite anode material
  • Preparation method of silicon-carbon-graphite composite anode material
  • Preparation method of silicon-carbon-graphite composite anode material

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] figure 1 (a) is silicon dioxide SiO 2 SEM image of nanopowder, SiO 2 The size is between 10 and 20 nm. SiO 2 The nanopowder and carbon source pitch are mixed uniformly according to the mass ratio of 1:0.5, and then kept at 700°C for 5 hours under an argon protective atmosphere, and finally cooled to room temperature to obtain carbon-coated silicon dioxide SiO 2 / C, such as figure 1 (b) shown. It can be seen that SiO 2 / C is also in powder form, and its size is larger than that of SiO 2 The nano-powder increases, with an average of 20nm. According to Mg:SiO 2 The molar ratio is 2:1, respectively weigh SiO 2 / C Nano powder and magnesium powder (wherein SiO 2 SiO in / C 2 The mass content was measured to be 70%), and mixed well, and reacted at 600° C. for 8 hours under an argon protective atmosphere. After it was naturally cooled to room temperature, it was stirred in dilute hydrochloric acid solution, and filtered and washed with alcohol and deionized water to ...

Embodiment 2

[0025] SiO 2 Nano powder and carbon source phenolic resin are mixed evenly according to the mass ratio of 1:1, and then kept at 800°C for 4 hours under the protective atmosphere of argon, and finally cooled to room temperature to obtain carbon-coated silicon dioxide SiO 2 / C. According to Mg:SiO 2 The molar ratio is 2:1 to weigh SiO 2 / C Nano-powder and magnesium powder, and fully mixed, reacted at 650°C for 5 hours under an argon protective atmosphere. After it was naturally cooled to room temperature, it was stirred in dilute sulfuric acid solution, and filtered and washed with alcohol and deionized water to obtain carbon-coated nano-Si / C. image 3 (a) is a scanning electron microscope photo after the two materials are fully mixed and uniform according to the mass ratio Si / C:graphite is 1:2.5. It can be seen that the nano-scale Si / C powder adheres to the surface of the graphite powder . image 3 (b) is the X-ray diffraction spectrum of this material, it can be seen that...

Embodiment 3

[0027] SiO 2Nano powder and carbon source starch were mixed evenly according to the mass ratio of 1:2.5, then kept at 900°C for 3 hours under nitrogen protection atmosphere, and finally cooled to room temperature to obtain carbon-coated silicon dioxide SiO 2 / C. According to Mg:SiO 2 The molar ratio is 2:1, respectively weigh SiO 2 / C Nano-powder and magnesium powder, and mix well, and react at 700°C for 3 hours under nitrogen protection atmosphere. After it was naturally cooled to room temperature, it was stirred in dilute nitric acid solution, and filtered and washed with alcohol and deionized water to obtain carbon-coated nano-Si / C. Figure 4 (a) is a scanning electron microscope photo after the two materials are fully mixed and uniform according to the mass ratio Si / C:graphite is 1:1. It can be seen that the nano-scale Si / C powder adheres to the surface of the graphite powder . Figure 4 (b) is the X-ray diffraction spectrum of this material, it can be seen that it is...

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Abstract

The invention relates to a preparation method of a silicon-carbon-graphite composite anode material. The method comprises the following steps of carrying out carbon coating on nanosilicon dioxide powder; with magnesium powder as a reducing agent, reducing carbon-coated nanosilicon dioxide into carbon-coated nanosilicon through magnesiothermic reduction; and with the carbon-coated nanosilicon as a raw material, fully mixing the carbon-coated nanosilicon with graphite powder at a certain mass ratio to prepare the silicon-carbon-graphite composite anode material. The required reduction temperature is low; the preparation technology is simple; mass production is easy to achieve; and the prepared composite material has excellent cycle performance and relatively high first cycle columbic efficiency when applied to a positive electrode of a lithium-ion battery.

Description

technical field [0001] The invention relates to preparing carbon-coated nano-silicon by a magnesia thermal reduction method, and mixing it with graphite in a certain proportion to prepare a silicon-carbon-graphite composite material, which is used as a negative electrode material of a lithium ion battery, and belongs to the field of functional materials. Background technique [0002] As an anode material for lithium-ion batteries, silicon has a theoretical specific capacity of 4200mAh / g, which has attracted extensive attention and research. However, the conductivity of silicon is poor, the first cycle coulombic efficiency is low, and there is a drastic volume change (>300%) during the charging and discharging process, which makes the silicon material easy to pulverize, and the electrical contact performance between particles is reduced, resulting in poor cycle performance. . In order to reduce the impact of this volume change, currently commonly used modification methods...

Claims

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Application Information

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IPC IPC(8): H01M4/36H01M4/38H01M4/62H01M4/139B82Y30/00H01M10/0525
CPCB82Y30/00H01M4/139H01M4/362H01M4/38H01M4/625H01M10/0525Y02E60/10
Inventor 陈玉喜潘梦洁
Owner HUNAN UNIV
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