Multi-heteroatom co-doped carbon shell coated silicon composite material and preparation method thereof

A composite material and a heteroatom technology, which is applied to the composite material and the preparation field of multi-heteroatom co-doped carbon shell-coated silicon, can solve the problems of low reversible capacity, unsatisfactory cycle stability, etc. The effect of improving transport and diffusion rates and ensuring structural stability

Active Publication Date: 2020-09-18
HUNAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art, to provide a composite material of multi-heteroatom-doped co-carbon shell-coated silicon and a preparation method thereof. While improving the electronic conductivity and interface stability of the negative electrode material, the present invention, A cavity structure is also introduced between the carbon layer and the silicon core to buffer the volume change of the silicon material during the process of intercalation and delithiation, and solve the problem of low reversible capacity and unsatisfactory cycle stability of silicon-carbon composite materials in the prior art question

Method used

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  • Multi-heteroatom co-doped carbon shell coated silicon composite material and preparation method thereof
  • Multi-heteroatom co-doped carbon shell coated silicon composite material and preparation method thereof
  • Multi-heteroatom co-doped carbon shell coated silicon composite material and preparation method thereof

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Effect test

Embodiment 1

[0035] (1) Pretreatment of carbon precursor: Weigh 2g of medium-temperature pitch, grind it into powder in a mortar, pour it into a conical flask containing 50ml of toluene solution, and stir for 20min; then weigh 2g of melamine, 1g of sublimated sulfur, 0.5g of sodium tetraphenylborate and 1g of red phosphorus were added to the above solution in turn, ultrasonicated for 10 minutes, and then evaporated to dryness while stirring to obtain a medium temperature pitch mixed with nitrogen source, sulfur source, boron source and phosphorus source.

[0036] (2) Oxidation treatment of silicon powder: put industrial silicon powder and water into a ball mill tank at a mass ratio of 1:1, pass in argon gas protection, and then perform high-energy ball milling at a speed of 1000r / min for 2 hours. The treated powder was transferred to a tube furnace and heated to 800 °C for 2 h under the protection of argon to obtain SiO 2 and Si mixture.

[0037] (3) Carbon coating treatment: doped pitch,...

Embodiment 2

[0042] (1) Pretreatment of carbon precursor: Weigh 2g of medium-temperature pitch, grind it into powder in a mortar, pour it into a conical flask containing 50ml of toluene solution, and stir for 20min; then weigh 2g of melamine, 1g of thiourea, 0.5 g of boric acid was added to the above solution in turn, ultrasonically treated for 10 min, and then evaporated to dryness while stirring to obtain a medium-temperature pitch mixed with nitrogen source, sulfur source and boron source.

[0043] (2) Oxidation treatment of silicon powder: put industrial silicon powder and water into a ball mill tank at a mass ratio of 1:0.5, pass in argon gas protection, and then perform high-energy ball milling treatment at a speed of 1000r / min for 3 hours. The treated powder was transferred to a tube furnace and heated to 800 °C for 2 h under the protection of argon to obtain SiO 2 and Si mixture.

[0044] (3) Carbon coating treatment: doped pitch, SiO 2 / Si mixture and conductive carbon black are...

Embodiment 3

[0048] (1) Pretreatment of carbon precursor: Weigh 2g of phenolic resin, grind it into powder in a mortar, pour it into a conical flask containing 50ml of ethanol solution, and stir for 20min; then weigh 2g of urea, 1g of ethylphosphonic acid Sequentially added to the above solution, treated with ultrasound for 10 minutes, and then evaporated to dryness while stirring to obtain medium-temperature asphalt mixed with nitrogen source and phosphorus source.

[0049] (2) Oxidation treatment of silicon powder: put industrial silicon powder and water into a ball mill tank at a mass ratio of 1:3, pass through argon protection, and then perform high-energy ball milling at a speed of 1000r / min for 4 hours. The treated powder was transferred to a tube furnace and heated to 800 °C for 2 h under the protection of argon to obtain SiO 2 and Si mixture.

[0050] (3) Carbon coating treatment: the doped phenolic resin, SiO 2 / Si mixture and graphene are packed in the ball mill jar according t...

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Abstract

The invention belongs to the field of lithium ion battery negative electrode materials, and particularly relates to a multi-heteroatom co-doped carbon shell coated silicon composite material and a preparation method thereof. According to the composite material, nanoscale silicon particles serve as a core, a multi-heteroatom co-doped carbon material serves as a shell, a cavity exists between the silicon core and the carbon shell, and the silicon core and the carbon shell are connected through a conductive additive; the types of heteroatoms in the multi-heteroatom co-doped carbon material are one or more of N, S, P and B types; and the conductive additive is one or more of carbon nanotubes, conductive carbon black, graphene and carbon nanofibers. Meanwhile, the invention further provides a preparation method and application of the composite material. The prepared material is good in cycle performance. The size of the cavity can be regulated and controlled through the heat treatment time;whole conductive performance is good.

Description

technical field [0001] The invention belongs to the field of negative electrode materials for lithium ion batteries, in particular to a composite material of multi-heteroatom co-doped carbon shell-coated silicon and a preparation method thereof. Background technique [0002] Compared with graphite anode materials with a theoretical capacity of only 372mAh / g, silicon-based anode materials have obvious advantages in energy density, with a theoretical specific capacity of up to 4200mAh / g, low cost, and good environmental compatibility. They are the most promising next-generation lithium-ion materials. Battery negative electrode material. However, silicon-based materials mainly face two obstacles in the actual use process: (1) The volume of silicon will expand by 300% during the charging and discharging process, and the huge volume effect will cause the silicon structure to collapse, which will eventually lead to a large capacity decay during cycling. quick. (2) Silicon is a s...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/583H01M4/62H01M10/0525
CPCH01M4/366H01M4/386H01M4/583H01M4/62H01M4/625H01M10/0525Y02E60/10
Inventor 韩飞刘金水项品峰汪卫斌
Owner HUNAN UNIV
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