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 the problems of electrode cycle performance decline, limited commercial application, material structure damage, etc. To achieve the effect of convenient and practical preparation process, increase of irreversible capacity, and increase of specific surface area

Active Publication Date: 2015-04-22
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] Prepare a certain concentration of graphene oxide dispersion by Hummer method, adjust the concentration of graphene oxide dispersion to 1mg / ml, add graphite powder (D50: 0.5μm) and nano-silicon (D50: 1nm) to the dispersion at the same time, graphite The mass ratio of micropowder and nano-silicon is 9: 1, adds dispersant polyethylene glycol 200 simultaneously (add-on is added by accounting for 1wt% of nano-silicon / graphite micropowder total mass), controls graphene oxide: nano-silicon and graphite micropowder The mass ratio is 1:20. Ultrasonic plus mechanical stirring is used to disperse 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 500°C for 2 hours, and then cooled with the furnace to obtain a thermally reduced graphene-coated silicon-carbon composite negative electrod...

Embodiment 2

[0027] Use the 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 with nano-silicon is 8:2, add dispersing agent polyvinyl alcohol simultaneously (add-on adds by accounting for 2wt% of nano-silicon / graphite micropowder gross mass), control graphene oxide: the mass ratio of nano-silicon and graphite micropowder is 5:20, ultrasound plus mechanical stirring for 1 hour to obtain a uniformly dispersed suspension, spray-dry the suspension at 170-200°C to obtain the composite material precursor. The obtained powder was transferred into an argon atmosphere and treated at a constant temperature of 600°C for 2 hours, and then cooled with the furnace to obtain a thermally reduced graphene-coated silicon-carbon composite negative electrode material.

[0028] The mixing r...

Embodiment 3

[0030] Use the Hummer method to prepare a certain concentration of graphene oxide dispersion, adjust the concentration of graphene oxide dispersion to 5mg / ml, add graphite powder (D50: 3μm) and nano-silicon (D50: 300nm) to the dispersion at the same time, graphite powder The mass ratio with nano-silicon is 7:3, while adding dispersant polyethylene oxide ((the addition is added by 2wt% accounting for the total mass of nano-silicon / graphite micropowder), control graphene oxide: the mass ratio of nano-silicon and graphite micropowder The ratio is 2.5:20, ultrasonic plus mechanical stirring for 2 hours to obtain a uniformly dispersed suspension, and after the suspension is spray-dried at 170-200°C, the composite material precursor is obtained. The obtained powder is transferred to an argon atmosphere and placed at a constant temperature of 800°C After processing for 2 hours, cooling with the furnace, the heat-reduced graphene-coated silicon-carbon composite negative electrode mater...

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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 lithium ion battery composite negative electrode materials. Background technique [0002] Lithium-ion batteries are widely used in various portable electronic devices and electric vehicles due to their advantages such as high energy density, high working voltage, low self-discharge rate, small size, light weight, and long cycle life. At present, the commercial lithium-ion battery anode materials are mainly graphite-based anode materials, but because the theoretical specific capacity is only 372mAh / g, it gradually cannot meet people's needs for high energy density batteries. Therefore, the development of new negative electrode materials with high specific capacity, high charge-discharge efficiency, and high cycle stability has become a current research hotspot. [0003] In recent years, silicon's high theoretical s...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/1395H01M4/38H01M4/587H01M4/62B82Y30/00
CPCY02E60/122Y02E60/10
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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