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A kind of sulfur-nitrogen doped carbon nanofiber-mxene composite material for lithium-sulfur battery cathode material and preparation method thereof

A nanofiber, nitrogen-doped carbon technology, applied in the field of materials, can solve problems such as hindering the discharge reaction between electrolyte and electrode active material, loss of positive active material, and increase in electrode polarization resistance, so as to improve cycle stability and reduce Active material agglomeration, small pore size effect

Active Publication Date: 2021-01-15
INT ACAD OF OPTOELECTRONICS AT ZHAOQING SOUTH CHINA NORMAL UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Studies have shown that the dissolution and diffusion of a large amount of polylithium sulfide in the electrolyte will lead to the loss of positive active materials and reduce the cycle life of the battery; in addition, the discharge product lithium sulfide Li 2 S 2 and Li 2 S will precipitate from the organic electrolyte and cover the surface of the sulfur cathode, forming an insulating lithium sulfide film, which hinders the discharge reaction between the electrolyte and the electrode active material.
(3) The chemical properties of metal lithium are very active, and it is easy to react with the electrolyte solution, and an SEI film is formed on the surface of the electrode material, resulting in an increase in the polarization resistance of the electrode; the dissolved high-polymer polysulfide will diffuse to the lithium surface and form a self-reaction with lithium. The discharge corrosion reaction leads to irreversible capacity loss of the active material; at the same time, the reduction product of some oligomerization states diffuses back to the positive electrode under the action of the concentration gradient for re-oxidation, thereby producing the shuttle effect and reducing the electric Coulombic efficiency.
In addition, part of lithium will lose its activity during charging and discharging, and become irreversible "dead lithium"; and due to the inhomogeneity of the electrode surface, lithium dendrites may be formed, causing safety problems.

Method used

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  • A kind of sulfur-nitrogen doped carbon nanofiber-mxene composite material for lithium-sulfur battery cathode material and preparation method thereof
  • A kind of sulfur-nitrogen doped carbon nanofiber-mxene composite material for lithium-sulfur battery cathode material and preparation method thereof

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] (1) Preparation of MXene:

[0028] Immerse the ground MAX phase ceramic powder in HF solution with a mass fraction of 40%, the mass ratio of ceramic powder to HF solution is 1:20, heat up to 60°C, stir magnetically for 18 hours, then centrifuge to obtain the product, and use deionized Wash with water until neutral, and dry in an oven at 70°C for 18 hours to obtain MXene. The MAX phase ceramic is Ti 3 AlC 2 , to get the MXene material as Ti 3 C 2 .

[0029] (2) Preparation of nitrogen-doped carbon nanofiber-MXene composites:

[0030] Get 1.5g polyacrylonitrile, the Ti prepared in 1.5g step (1) 3 C 2 , placed in 15mL N,N-dimethylformamide, stirred for 18 hours, and the homogeneous solution was taken to prepare MXene-doped polyacrylonitrile nanofibers by electrospinning. Then the prepared MXene-doped polyacrylonitrile nanofibers were placed in a tube furnace, calcined at 800°C for 3 hours under an argon atmosphere, and nitrogen-doped carbon nanofiber-MXene composit...

Embodiment 2

[0036] (1) Preparation of MXene:

[0037] Immerse the ground MAX phase ceramic powder in HF solution with a mass fraction of 30%, the mass ratio of ceramic powder to HF solution is 1:30, heat up to 50°C, stir magnetically for 12 hours, then centrifuge to obtain the product, and use deionized Wash with water until neutral, and dry in an oven at 60°C for 12 hours to obtain MXene. The MAX phase ceramic can be Ti 3 AlC 2 , to get the MXene material as Ti 3 C 2 .

[0038] (2) Preparation of nitrogen-doped carbon nanofiber-MXene composites:

[0039] Take 1g of polyacrylonitrile and 1g of MXene prepared in step (1), put them in 10mL of N,N-dimethylformamide, stir for 12 hours and take a homogeneous solution to prepare MXene-doped polyacrylonitrile nanoparticles by electrospinning fiber. Then the prepared MXene-doped polyacrylonitrile nanofibers were placed in a tube furnace, calcined at 500°C for 2 hours under an argon atmosphere, and nitrogen-doped carbon nanofiber-MXene comp...

Embodiment 3

[0043] (1) Preparation of MXene:

[0044] Immerse the ground MAX phase ceramic powder in HF solution with a mass fraction of 50%, the mass ratio of ceramic powder to HF solution is 1:10, heat up to 90°C, stir magnetically for 24 hours, then centrifuge to obtain the product, and use deionized Wash with water until neutral, and dry in an oven at 80°C for 24 hours to obtain MXene. The MAX phase ceramic is Ti 3 AlC 2 , to get the MXene material as Ti 3 C 2 .

[0045] (2) Preparation of nitrogen-doped carbon nanofiber-MXene composites:

[0046] Take 2g of polyacrylonitrile and 2g of MXene prepared in step (1), put them in 20mL N,N-dimethylformamide, stir for 24 hours and take a homogeneous solution to prepare MXene-doped polyacrylonitrile nanoparticles by electrospinning fiber. Then the prepared MXene-doped polyacrylonitrile nanofibers were placed in a tube furnace and calcined at 1000°C for 5 hours under an argon atmosphere, and nitrogen-doped carbon nanofiber-MXene composi...

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Abstract

The invention relates to a sulfur-nitrogen doped carbon nanofiber-MXene composite material for lithium-sulfur battery cathode materials and a preparation method thereof. Specifically, Mxene-doped polyacrylonitrile nanofibers were prepared by electrospinning technology, and nitrogen-doped carbon nanofiber-MXene composites were obtained by high-temperature carbonization, and then sulfur-nitrogen-doped carbon was prepared by doping sulfur by ball milling and hot melting. Nanofiber-MXene composite material, when the prepared composite material is used as a positive electrode material for lithium-sulfur batteries, it can effectively absorb lithium polysulfide, inhibit the shuttle effect, and alleviate the beneficial effect of volume expansion during charge and discharge.

Description

technical field [0001] The technical solution of the present invention relates to a method for preparing a high-capacity lithium-sulfur battery positive electrode material, in particular to a method for preparing MXene-doped polyacrylonitrile nanofibers by electrospinning, and then performing high-temperature calcination to obtain nitrogen-doped A carbon nanofiber-MXene composite lithium-sulfur battery cathode material method belongs to the field of material chemistry. Background technique [0002] With the successful commercial use of graphite anodes, lithium-ion batteries have been widely used in portable electronic devices such as smartphones and laptops. After more than 20 years of development, the existing lithium-ion batteries based on lithium-intercalated compound cathodes are close to their theoretical capacity, but they still cannot meet the requirements of the rapidly developing electronics industry and emerging electric vehicles. Looking for batteries with higher ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/36H01M4/583H01M4/62H01M10/052C01B32/907C01B32/15
CPCC01B32/15C01B32/907H01M4/362H01M4/583H01M4/625H01M10/052Y02E60/10
Inventor 张永光王加义
Owner INT ACAD OF OPTOELECTRONICS AT ZHAOQING SOUTH CHINA NORMAL UNIV