A kind of cathode material for lithium-sulfur battery and using method thereof

A positive electrode material, lithium-sulfur battery technology, applied in battery electrodes, lithium batteries, electrode carriers/collectors, etc., can solve problems such as poor ion and electron conductivity, reduced energy conversion efficiency, and reduced battery energy density. Guaranteed cycle stability, cycle stability guarantee, and the effect of improving electrochemical performance

Active Publication Date: 2019-07-02
SHENZHEN GRADUATE SCHOOL TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, the current lithium-sulfur battery system has not been industrialized for a long time, mainly due to several reasons
The first is the positive electrode material sulfur and its many discharge products during the discharge process (Li 2 Sx, x=1-8) has poor ion and electron conductivity
This greatly increases the internal impedance of the battery, which easily causes a large polarization tendency, which in turn leads to a decrease in energy conversion efficiency.
At the same time, with Li 2 S 2 and Li 2 The intermediate product represented by S is easy to deposit on the surface of sulfur particles, which affects the full utilization of sulfur in the positive electrode and reduces the energy density of the battery.
The second reason is also caused by polysulfide compounds in the discharge product, polysulfide compounds with higher valence states of sulfur (Li 2 Sx, x=4-8) is easy to dissolve in the electrolyte or react with the electrolyte, which makes the overall capacity of the battery undergo continuous irreversible attenuation
However, most of the conductive frameworks of carbon nanotubes currently used in electrode materials are in a disordered state. The sulfur load in the conductive network constructed by disordered carbon nanotubes often results in a significant increase in the contact resistance of the conductive network at the carbon nanotube overlap, which cannot Give full play to the advantages of carbon nanotubes

Method used

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  • A kind of cathode material for lithium-sulfur battery and using method thereof
  • A kind of cathode material for lithium-sulfur battery and using method thereof
  • A kind of cathode material for lithium-sulfur battery and using method thereof

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Experimental program
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Effect test

Embodiment 1

[0024] Preparation of sheet-like carbon nanotube bulk material: inject 5wt% carbon nanotube aqueous slurry into the designed mold, the mass fraction of polyvinylpyrrolidone in the slurry is 1.2wt%, and then mold the mold at a rate of 50cm / h Immerse in constant temperature liquid nitrogen at -196°C at a high speed. After the slurry is completely solidified, quickly transfer it to a freeze dryer, and freeze-dry it at -5°C with a final vacuum of 1Pa. Cross-sectional SEM of layered carbon nanotube bulk material such as figure 1 with 2 shown. The thickness of the sheets is 10 μm, and the distance between adjacent sheets is 200 μm.

[0025] Pre-shaping of carbon nanotube block material: place the above-mentioned carbon nanotube block material between two highly flat stainless steel ingots, and place the direction so that the layer direction of the carbon nanotube block material is parallel to the stainless steel plane. The above-mentioned carbon nanotube bulk material is then com...

Embodiment 2

[0028] Preparation of sheet-like carbon nanotube bulk material: inject 1wt% carbon nanotube aqueous slurry into the designed mold, the mass fraction of polyvinylpyrrolidone in the slurry is 0.2wt%, and then mold the mold at a rate of 10cm / h Immerse in a constant temperature alcohol bath at -10°C at a high speed. After the slurry is completely solidified, quickly transfer it to a freeze dryer, and freeze-dry at -5°C with a final vacuum of 5Pa. The thickness of the sheets is 500 nm, and the distance between adjacent sheets is 10 μm.

[0029] Pre-shaping of carbon nanotube block material: place the above-mentioned carbon nanotube block material between two highly flat stainless steel ingots, and place the direction so that the layer direction of the carbon nanotube block material is parallel to the stainless steel plane. The above-mentioned carbon nanotube bulk material is then compressed along the direction perpendicular to the sheets.

[0030] Preparation of Lithium-Sulfur Bat...

Embodiment 3

[0032] Preparation of sheet-like carbon nanotube bulk material: inject 3wt% carbon nanotube aqueous slurry into the designed mold, the mass fraction of polyvinylpyrrolidone in the slurry is 0.7wt%, and then mold the mold at a rate of 5cm / h Immerse in a constant temperature alcohol bath at -30°C at a high speed. After the slurry is completely solidified, quickly transfer it to a freeze dryer, and freeze-dry at 0°C with a final vacuum of 10Pa. The thickness of the sheets is 45 μm, and the distance between adjacent sheets is 2 μm.

[0033] Pre-shaping of carbon nanotube block material: place the above-mentioned carbon nanotube block material between two highly flat stainless steel ingots, and place the direction so that the layer direction of the carbon nanotube block material is parallel to the stainless steel plane. The above-mentioned carbon nanotube bulk material is then compressed along the direction perpendicular to the sheets.

[0034] Preparation of Lithium-Sulfur Batter...

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Abstract

The invention discloses an anode material for a lithium sulfur battery and a using method thereof. The positive electrode material is mainly prepared from carbon nano-tubes and polyvinylpyrrolidone and has a structure of a block body with flakes and vertical through holes, which are parallel to each other. The using method comprises the following steps: pressing the block body along the direction of vertical flakes, soaking in a sulfur-containing solution or dropwise adding the sulfur-containing solution onto the block body, and directly using as the anode of a lithium sulfur battery. The anode material can be used for remarkably improving the conductivity of the anode of a lithium sulfur battery and remarkably reducing the shuttle effect of polysulfide, so that the electrochemical comprehensive performance of the lithium sulfur battery is greatly improved.

Description

technical field [0001] The invention belongs to the field of secondary batteries, in particular to a positive electrode material for a lithium-sulfur battery and a use method thereof. Background technique [0002] With the continuous reduction of fossil energy, people's demand for new energy is increasing. Lithium-ion secondary batteries with rechargeable and discharge capabilities have been widely concerned and favored since their inception. Since Japan's Sony Corporation realized the industrialization of lithium-ion batteries worldwide in 1991, people's attention to lithium-ion batteries has gradually deepened step by step. In particular, due to the limitations in energy density of traditional lithium-ion battery systems (lithium cobaltate / graphite and lithium iron phosphate / graphite systems), research on other secondary battery systems has intensified in recent years. Among them, it is worth mentioning that the lithium-sulfur battery system uses metallic lithium as the ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/58H01M4/66H01M4/80H01M4/62H01M10/052
CPCH01M4/362H01M4/38H01M4/5815H01M4/62H01M4/625H01M4/663H01M4/666H01M4/80H01M10/052Y02E60/10
Inventor 吕伟潘郑泽杨全红赵严牛树章石会发游从辉康飞宇
Owner SHENZHEN GRADUATE SCHOOL TSINGHUA UNIV
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