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Directional carbon nano-tube composite cathode material for lithium-sulfur secondary battery

A carbon nanotube composite, lithium-sulfur secondary battery technology, applied in battery electrodes, circuits, electrical components, etc., can solve the problems of increased contact resistance of conductive networks and low carbon nanotube lengths, and achieves improved electrical conductivity and overcomes electrical conductivity. Insufficient rate and overcoming the effect of irregular pores

Active Publication Date: 2012-07-18
TSINGHUA UNIV
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  • Abstract
  • Description
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  • Application Information

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Problems solved by technology

However, most of the conductive frameworks of carbon nanotubes currently used in electrode materials are disordered and the length of carbon nanotubes is relatively low. The sulfur load in the conductive network constructed by disordered carbon nanotubes often causes the conductive network to overlap at the carbon nanotube overlap. The contact resistance has been greatly increased, and the advantages of the tubular material of carbon nanotubes have not been fully utilized

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  • Directional carbon nano-tube composite cathode material for lithium-sulfur secondary battery
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  • Directional carbon nano-tube composite cathode material for lithium-sulfur secondary battery

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[0018] The preparation of positive electrode materials is realized by the compounding of active materials on aligned carbon nanotubes. For example, elemental sulfur can be loaded into aligned carbon nanotubes after being heated and melted by sulfur, or loaded into aligned carbon nanotubes after gasification of elemental sulfur. Aligned carbon nanotubes can be loaded in the liquid phase through a sulfur solution; sulfur / polymer composites can also be loaded with sulfur in the aligned carbon nanotubes and then composite polymers, or composite polymers in the aligned carbon nanotubes first and then The way of loading sulfur is filled into the pores of aligned carbon nanotubes. The polymer is one or more of polyaniline, polyacrylonitrile, polypyrrole, polythiophene, polyethylene oxide and polyethylene glycol. The mass ratio of the sulfur in the active material to the carbon element in the polymer is 1:0-5; the mass ratio of the carbon nanotube to the active material in the composi...

Embodiment 1

[0021] Embodiment 1: adopt thermal chemical vapor deposition process to prepare aligned carbon nanotubes on the surface of a silicon wafer coated with a catalyst, the thickness of the carbon nanotube film is about 100 microns, and the diameter of the carbon nanotubes is 8 nanometers (attached figure 1 ). The aligned carbon nanotube film was peeled off from the surface of the silicon wafer; and co-thermally composited with sublimed sulfur powder at 155°C to form a positive electrode material, and the top electron micrograph showed that sulfur was distributed between the pores of the aligned carbon nanotubes (attached figure 2 ). The mass ratio of the aligned carbon nanotubes to the active material elemental sulfur is 1:10. The disordered carbon nanotube / elemental sulfur composite material was prepared at the same mass ratio, and mixed with a binder and coated on the surface of aluminum foil as a comparative positive electrode material sample. The assembly test results show t...

Embodiment 2

[0022] Embodiment 2: Utilize planktonic chemical vapor deposition process to prepare oriented carbon nanotube film on the surface of quartz plate, the thickness of film is 1000 microns, and the carbon nanotube tube diameter in directional carbon nanotube is 100 nanometers, and approximately parallel arrangement forms array structure (attachment Figure 4 ). The aligned carbon nanotube film is separated from the quartz surface, and used as a working electrode for electrochemical deposition of polyaniline, and the prepared polyaniline is deposited in the aligned carbon nanotube. After cleaning, the aligned carbon nanotube film is impregnated with sulfur carbon disulfide solution, and the polymer is obtained after the carbon disulfide volatilizes, and the sulfur mixture is used as the positive electrode material of the active material. The material is subjected to heat treatment at 250° C. under an inert atmosphere to form bonds between the sulfur and polyaniline moieties. In th...

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Abstract

The invention discloses a directional carbon nano-tube composite cathode material for a lithium-sulfur secondary battery. A structure consisting of carbon nano-tubes with orientation, namely the directional carbon nano-tubes is used as a framework of the material, a carbon nano-tube / sulfur composite material is obtained by compounding, and the composite material can be used as the cathode material of the lithium-sulfur secondary battery. In a conductive network constructed by using disordered carbon nano-tubes, the contact resistance at a lap joint of the carbon nano-tubes in the conductive network is always greatly increased by the load of sulfur; however, with the adoption of the directional carbon nano-tubes, an electron channel contacts a current collector through one carbon nano-tube, so that the generation of a large amount of contact resistance is avoided, and an efficient conductive network is provided. Meanwhile, an ordered pore structure of a directional carbon nano-tube electrode also ensures that an ion channel is smooth, so that the cathode material has high cycle performance, is a high-performance cathode material, and is expected to promote further enhancement of the performance of the lithium-sulfur secondary battery and the industrial application of the lithium-sulfur secondary battery.

Description

field of invention [0001] The invention relates to a positive electrode material for a lithium-sulfur secondary battery, in particular to an aligned carbon nanotube composite positive electrode material for a lithium-sulfur secondary battery. Background technique [0002] The development of the modern electronics industry has continuously improved the performance of portable devices, and has also put forward higher and higher requirements for battery energy density; on the other hand, batteries for electric vehicles also have extremely high requirements for batteries with high specific energy. The performance of existing lithium-ion batteries cannot meet the requirements of these devices gradually, and it is imperative to develop new high-energy battery systems. [0003] Sulfur is a positive electrode material with high theoretical specific capacity, the theoretical capacity can reach 1672mAh / g, and the theoretical energy density of the battery composed of lithium negative e...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/62
CPCY02E60/12Y02E60/10
Inventor 魏飞黄佳琦张强刘晓斐张书锚朱万诚
Owner TSINGHUA UNIV
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