Silicon-carbon composite material as well as preparation method and application thereof

A technology of silicon-carbon composite material and negative electrode material, which is applied in the preparation/purification of carbon, nanotechnology for materials and surface science, silicon, etc., and can solve the problems of cumbersome process, consumption of electrolyte, discharge of toxic chemicals, etc. Achieve high electrochemical lithium storage capacity, volume expansion mitigation, and volume expansion inhibition effects

Active Publication Date: 2022-03-01
FUJIAN INST OF RES ON THE STRUCTURE OF MATTER CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, silicon-based materials also have many inherent defects including: low Li diffusion rate and electronic conductivity; large volume expansion (300%) during the alloying reaction process of silicon, resulting in pulverization of silicon, poor electrochemical contact, and solid electrolyte Repeated destruction and generation of solid electrolyte interphases (SEI) will consume electrolyte and reduce Coulombic efficiency and cycle life
So far, the preparation of silicon-graphene composites is often accompanied by cumbersome processes, high costs and toxic chemical emissions.

Method used

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  • Silicon-carbon composite material as well as preparation method and application thereof
  • Silicon-carbon composite material as well as preparation method and application thereof
  • Silicon-carbon composite material as well as preparation method and application thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0081] A method for preparing a silicon-carbon composite material, comprising the steps of:

[0082] (1) Annealing the petroleum pitch at 400° C. for 4 hours in an inert atmosphere to obtain a mesophase pitch (that is, a graphene-like carbon nanosheet precursor), and then fully ultrasonically dissolving 225 mg of the mesophase pitch in 15 ml of toluene solution;

[0083] (2) The organic solution containing mesophase pitch prepared by 10g of LiCl-KCl (59%:41% (mol%)), 200mg of nano-silicon powder and step (1) is added successively in the planetary ball mill tank, ball milled for 2h, and the speed 600rpm;

[0084] (3) Vacuum drying the ball-milled slurry obtained in step (2) at 100° C., and grinding it into a uniform powder to obtain a mixed precursor powder;

[0085] (4) Anneal the mixed precursor powder obtained in step (3) in a tube furnace with argon flow at 5 °C min -1 The speed is increased to 360°C for 1h, and then at 10°C·min -1 The temperature was raised to 700°C and...

Embodiment 2

[0087] A method for preparing a silicon-carbon composite material, comprising the steps of:

[0088] (1) Annealing the petroleum pitch at 400° C. for 4 hours in an inert atmosphere to obtain a mesophase pitch (that is, a graphene-like carbon nanosheet precursor), and then fully ultrasonically dissolving 225 mg of the mesophase pitch in 15 ml of toluene solution;

[0089] (2) Add 10g of CaCl 2 -NaCl (55%:45% (mol%)), 200mg of nano-silica powder and the organic solution containing mesophase pitch prepared in step (1) were successively added to the planetary ball mill tank, ball milled for 2h, and the rotating speed was 600rpm;

[0090] (3) Vacuum drying the ball-milled slurry obtained in step (2) at 100° C., and grinding it into a uniform powder to obtain a mixed precursor powder;

[0091] (4) The mixed precursor powder obtained in step (3) is annealed in a tube furnace with an argon gas flow at 8°C min -1 The rate is increased to 550 ° C for 2 hours, the temperature is lowere...

Embodiment 3

[0093] A method for preparing a silicon-carbon composite material, comprising the steps of:

[0094] (1) Annealing the petroleum pitch at 400° C. for 4 hours in an inert atmosphere to obtain a mesophase pitch (that is, a graphene-like carbon nanosheet precursor), and then fully ultrasonically dissolving 225 mg of the mesophase pitch in 15 ml of toluene solution;

[0095](2) The organic solution containing mesophase pitch prepared by 10g of NaCl-KCl (50%:50% (mol%)), 200mg of nano-silicon powder and step (1) is added successively in the planetary ball mill tank, ball milled for 2h, rotating speed 600rpm;

[0096] (3) Vacuum drying the ball-milled slurry obtained in step (2) at 100° C., and grinding it into a uniform powder to obtain a mixed precursor powder;

[0097] (4) Anneal the mixed precursor powder obtained in step (3) in a tube furnace with argon flow at 8°C min -1 The rate is increased to 700°C for 1h, the temperature is lowered to room temperature, and 1mol·L -1 Dil...

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Abstract

The invention discloses a silicon-carbon composite material as well as a preparation method and application thereof. The silicon-carbon composite material comprises nano silicon and graphene-like carbon nanosheets, the nano silicon is coated by the graphene-like carbon nanosheet; and a silicon-oxygen layer exists between the graphene-like carbon nanosheet and the nano silicon. The silicon-carbon composite material is of a graphene-like coated nano-silicon two-dimensional hierarchical nano-structure, and when the silicon-carbon composite material is used as a negative electrode material, an electrode has high conductivity, excellent cycling stability and good rate capability under large current. Meanwhile, the invention also discloses a preparation method of the silicon-carbon composite material, mesophase pitch is cracked under the assistance of a salt template to generate graphene-like carbon nanosheets with high specific surface area and high conductivity, so that one-pot commercial nano silicon particle surfaces are coated with graphene-like carbon layers; the problems of poor dispersion effect, non-uniform surface coating, easy agglomeration, fast capacity fading and the like of asphalt coated nano silicon are solved.

Description

technical field [0001] The application relates to a silicon-carbon composite material and its preparation method and application, belonging to the fields of electrochemistry and new energy. Background technique [0002] Lithium-ion batteries have been widely used in notebook computers, cameras, mobile phones and other devices due to their advantages of high voltage, high specific energy, long cycle life and environmental friendliness. With the shortage of fossil energy and the increasingly serious environmental pollution problems worldwide, countries around the world, including my country, are vigorously promoting the application of new energy vehicles powered by lithium-ion batteries. Compared with traditional graphite anodes, silicon-based materials have extremely high theoretical specific capacity (~4200mAh g -1 vs ~ 370m Ah g -1 (traditional graphite anode)), relatively low lithium intercalation potential (<0.5V vs Li + / Li) and high crustal reserves, it is conside...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/62H01M10/0525B82Y30/00C01B32/05C01B33/02C01B33/113
CPCH01M4/366H01M4/386H01M4/625H01M4/628H01M10/0525B82Y30/00C01B33/02C01B32/05C01B33/113H01M2004/021H01M2004/027C01P2004/64C01P2004/80C01P2006/40C01P2002/72C01P2004/03Y02E60/10
Inventor 刘骞温珍海
Owner FUJIAN INST OF RES ON THE STRUCTURE OF MATTER CHINESE ACAD OF SCI
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