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A lithium-sulfur pole piece with a functional protective layer and its preparation method and application

A protective layer, lithium-sulfur technology, applied in battery electrodes, lithium batteries, non-aqueous electrolyte battery electrodes, etc., can solve the problems of increasing electrolyte viscosity, low conductivity, destroying electrode structure, etc., and achieve the effect of improving capacity retention.

Active Publication Date: 2018-11-06
XIAMEN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] First, the electronic conductivity and ionic conductivity of elemental sulfur are poor, and the conductivity of sulfur materials at room temperature is extremely low (5.0×10 -30 S cm -1 ), the final product of the reaction Li 2 S 2 and Li 2 S is also an electronic insulator, which is not conducive to the high rate performance of the battery
[0005] Second, the intermediate discharge products of lithium-sulfur batteries will dissolve into the organic electrolyte, increasing the viscosity of the electrolyte and reducing the ion conductivity
[0006] Third, the final discharge product of lithium-sulfur batteries, Li 2 S n (n=1~2) Electronic insulation and insoluble in the electrolyte, deposited on the surface of the conductive framework; part of the lithium sulfide detaches from the conductive framework, and cannot react into sulfur or higher-order polysulfides through a reversible charging process, resulting in Great attenuation of capacity
[0007] Fourth, the densities of sulfur and lithium sulfide are 2.07 and 1.66 g cm respectively -3 , there is a volume expansion / contraction of up to 79% during the charge and discharge process, which will lead to changes in the morphology and structure of the positive electrode, resulting in the detachment of sulfur from the conductive framework, resulting in capacity attenuation; this volume effect is in the button battery It is not significant, but in large batteries, the volume effect will be enlarged, which will cause significant capacity fading, which may cause damage to the battery, and the huge volume change will destroy the electrode structure

Method used

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  • A lithium-sulfur pole piece with a functional protective layer and its preparation method and application
  • A lithium-sulfur pole piece with a functional protective layer and its preparation method and application
  • A lithium-sulfur pole piece with a functional protective layer and its preparation method and application

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Experimental program
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Effect test

Embodiment 1

[0037] 0.45g of perfluorosulfonic acid resin grafted with polytetrafluoroethylene and 0.05g of sodium hydroxymethylcellulose (CMC), styrene-butadiene and rubber (SBR) (2:3, w:w) mixed binder Add 20 g of a mixed solution of deionized water and ethanol (1:1, v:v) and stir it magnetically for 5 h. With elemental sulfur as the active material, the mass ratio of elemental sulfur: acetylene black: polyvinylidene fluoride is 7:2:1, and the aluminum foil is used as the current collector. No active material area, used for subsequent experiments. Evenly scrape-coat the coating slurry prepared above on the surface of the pole piece, control the thickness of the coating layer to 1 μm, wait for most of the solvent to volatilize, put it in a vacuum oven at 60°C to dry overnight to remove the solvent, and obtain elemental sulfur with a functional protective layer Pole piece (scanning electron microscope photo of elemental sulfur as figure 1 As shown, the scanning electron micrograph of the...

Embodiment 2

[0039]Put 0.9 g of graphene oxide and 0.1 g of polyethylene oxide (PEO) binder into 50 g of a mixed solution of deionized water and ethanol (1:1, v:v) and stir magnetically for 10 h. Copper sulfide is used as the active material, and the mass ratio of copper sulfide: acetylene black: polyvinylidene fluoride is 6:3:1, and the copper foil is used as the current collector. Active material area, used for subsequent experiments. Evenly scrape and coat the coating slurry prepared above on the surface of the pole piece, control the thickness of the coating layer to 3 μm, wait for most of the solvent to volatilize, put it in a vacuum oven and dry it at 60°C overnight to completely remove the solvent, and obtain a graphene oxide protective film. layer of copper sulfide pole piece.

[0040] The cross-sectional view of the copper sulfide pole piece is shown in image 3 As shown, the cross-sectional scanning electron microscope image of the copper sulfide pole piece with the graphene ox...

Embodiment 3

[0042] Put 1.9g of partially fluorinated sulfonic acid resin and 0.1g mixed binder of sodium hydroxymethylcellulose (CMC) and styrene-butadiene rubber (SBR) (2:3, w:w) into deionized water and ethanol (1:1, v:v) 100 g of the mixed solution was magnetically stirred for 20 h. Using polythiopyrrole as the active material, make polythiopyrrole: acetylene black: polyvinylidene fluoride with a mass ratio of 7:2:1, and use aluminum foil as the current collector with an area of ​​15cm×15cm, and reserve the edge of the electrode A 1.5 mm area of ​​no active material was used for subsequent experiments. Evenly scrape-coat the coating slurry prepared above on the surface of the pole piece, control the thickness of the coating layer to 5 μm, wait for most of the solvent to volatilize, put it in a vacuum oven and dry it overnight at 60°C to completely remove the solvent, and obtain a partially fluorinated sulfonate Polythiopyrrole battery pole piece with acid resin protective layer.

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Abstract

The invention provides a lithium-sulfur pole piece with a function protection layer and a preparation method and application thereof and relates to lithium-sulfur batteries.The lithium-sulfur pole piece with the function protection layer is provided with a lithium-sulfur pole piece body, the surface of the lithium-sulfur pole piece body is coated with the protective layer, and the protective layer is a negative charging ion compound protective layer or a negative charging ion compound and ion transfer polymer blend protective layer.The preparation method of the lithium-sulfur pole piece with the function protection layer includes the following steps that firstly, a blend of a negative charging ion compound or negative charging ion compound and an ion transfer polymer, an adhesive and a solvent are mixed and ball milled to obtain slurry; secondly, the surface of the lithium-sulfur pole piece body is coated with the slurry, and the lithium-sulfur pole piece with the function protection layer is obtained after drying.The lithium-sulfur pole piece with the function protection layer can be applied to lithium-sulfur battery preparation.

Description

technical field [0001] The invention relates to a lithium-sulfur battery, in particular to a lithium-sulfur pole piece with a functional protective layer and a preparation method and application thereof. Background technique [0002] With the development of fields such as electric vehicles, higher requirements have been put forward for the capacity and power of chemical power systems such as lithium-ion batteries, so the safety of batteries has also received more and more attention. Lithium-sulfur battery is a kind of lithium battery. Lithium-sulfur battery uses sulfur as the positive electrode of the battery and metal lithium as the negative electrode. The specific capacity is as high as 1675mAh / g, which is much higher than the capacity (<150mAh / g) of lithium cobalt oxide batteries widely used in commerce. In addition, sulfur is an environmentally friendly element that basically has no pollution to the environment, and is a very promising lithium battery. [0003] The ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/13H01M4/139H01M4/62H01M10/052
CPCH01M4/13H01M4/139H01M4/628H01M10/052Y02E60/10
Inventor 赵金保石川李超张鹏
Owner XIAMEN UNIV