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Preparation method of silicon and carbon-coated graphene composite cathode material

A graphene-coated, negative electrode material technology, applied in nanotechnology for materials and surface science, battery electrodes, electrical components, etc., can solve problems such as electrode cycle performance degradation, limited commercial applications, and material structure damage. Achieve the effect of convenient and practical preparation process, increase irreversible capacity, and increase specific surface area

Active Publication Date: 2013-04-17
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, due to the serious volume expansion and contraction of the silicon anode during the intercalation and deintercalation cycle of lithium, the material structure is destroyed and mechanically crushed, which leads to the degradation of the electrode cycle performance and limits its commercial application.

Method used

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  • Preparation method of silicon and carbon-coated graphene composite cathode material
  • Preparation method of silicon and carbon-coated graphene composite cathode material

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] The Hummer method is used to prepare a certain concentration of graphene oxide dispersion, adjust the concentration of the graphene oxide dispersion to 1mg / ml, and add graphite micropowder (D50: 0.5μm) and nano silicon (D50: 1nm) to the dispersion at the same time. Graphite The mass ratio of micropowder to nano silicon is 9:1, and dispersant polyethylene glycol 200 is added at the same time (addition is 1wt% of the total mass of nano silicon / graphite powder) to control graphene oxide: the ratio of nano silicon and graphite powder The mass ratio is 1:20, ultrasonic plus mechanical stirring and dispersion for 1 hour to obtain a uniformly dispersed suspension. After the suspension is spray-dried at 170-200°C, the composite precursor is obtained. The obtained powder was transferred to an argon atmosphere and treated at a constant temperature of 500° C. for 2 hours, and then cooled with the furnace to obtain thermally reduced graphene coated silicon-carbon composite negative e...

Embodiment 2

[0027] Use Hummer method to prepare a certain concentration of graphene oxide dispersion, adjust the concentration of graphene oxide dispersion to 10mg / ml, add graphite powder (D50: 5μm) and nano silicon (D50: 500nm) to the dispersion at the same time, graphite powder The mass ratio to nano-silicon is 8:2, and the dispersant polyvinyl alcohol is added at the same time (the amount added is 2wt% of the total mass of nano-silicon / graphite powder) to control the mass ratio of graphene oxide: nano-silicon and graphite powder to 5:20, ultrasonic and mechanical stirring and dispersion for 1 hour to obtain a uniformly dispersed suspension. After the suspension is spray-dried at 170-200°C, the composite material precursor is obtained. The obtained powder was transferred to an argon atmosphere and treated at a constant temperature of 600°C for 2 hours, and then cooled with the furnace to obtain thermally reduced graphene coated silicon-carbon composite negative electrode material.

[0028]...

Embodiment 3

[0030] Use Hummer method to prepare a certain concentration of graphene oxide dispersion, adjust the concentration of graphene oxide dispersion to 5mg / ml, and add graphite powder (D50: 3μm) and nano silicon (D50: 300nm) to the dispersion at the same time, graphite powder The mass ratio to nano silicon is 7:3, and the dispersant polyethylene oxide is added at the same time (the amount added is 2wt% of the total mass of nano silicon / graphite powder) to control the mass ratio of graphene oxide: nano silicon and graphite powder 2.5:20, ultrasonic and mechanical stirring and dispersion for 2h to obtain a uniformly dispersed suspension. After the suspension is spray-dried at 170~200℃, the composite precursor is obtained. The obtained powder is transferred to an argon atmosphere and kept at a constant temperature of 800℃ After 2 hours of treatment, cooling with the furnace, the graphene-coated silicon-carbon composite anode material can be reduced by heat.

[0031] The mixing ratio of g...

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Abstract

The invention discloses a preparation method of a silicon and carbon-coated graphene composite cathode material. The technical problem to be solved is to enhance the electronic conductivity of the silicon-based cathode material, buffer the volume effect produced in the process of deintercalation of the lithium in the silicon-based cathode material and enhance the structure stability in the circulation process of the material at the same time. The material is prepared by using a spray drying-thermally decomposing treatment process in the invention. The preparation method comprises the following steps of: evenly dispersing nano silicon and graphite micro powder in a dispersion solution of oxidized graphene, carrying out thermal treatment under an inert protection atmosphere after spray drying, subsequently cooling along a furnace to obtain the silicon and carbon-coated graphene composite cathode material. The extra binder does not need to add in the process of manufacturing balls in the invention and the outer oxidized graphene is thermally reduced in situ to graphene in the thermal treatment process of the composite precursor, so that the process is simple and easy to operate; and the practical degree is high. The prepared composite material has the advantages of great reversible capacity, designable capacity, good cycling performance and high-current discharging performance, high tap density and the like.

Description

Technical field [0001] The invention belongs to the field of lithium ion battery materials and preparation methods thereof, and relates to a preparation method of a lithium ion battery composite negative electrode material. Background technique [0002] Lithium-ion batteries are widely used in various portable electronic devices and electric vehicles due to their high energy density, high working voltage, low self-discharge rate, small size, light weight, and long cycle life. The current commercial anode materials for lithium-ion batteries are mainly graphite anode materials, but because their theoretical specific capacity is only 372mAh / g, they gradually cannot meet people's demand for high-energy density batteries. Therefore, the development of new negative electrode materials with high specific capacity, high charge and discharge efficiency, and high cycle stability has become a hot research topic. [0003] In recent years, silicon's high theoretical specific capacity (4200mAh / ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/1395H01M4/38H01M4/587H01M4/62B82Y30/00
CPCY02E60/10
Inventor 郭华军甘雷王志兴李新海黄思林苏明如彭文杰胡启阳张云河
Owner CENT SOUTH UNIV
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