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Composite binder for lithium-sulfur battery and preparation method thereof

A lithium-sulfur battery and binder technology, which is applied in battery electrodes, circuits, electrical components, etc., can solve the problem that the shuttle effect of polysulfides cannot be suppressed in lithium-sulfur batteries, the polysulfides have no adsorption capacity, and the electrode porosity increases. problems, to achieve the effect of improving electrochemical performance, increasing reversible discharge capacity, and weakening crystallization tendency

Active Publication Date: 2019-07-05
BEIJING INSTITUTE OF TECHNOLOGYGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] (1) PVDF is only a bonding component, has no electrochemical activity, and because it is very easy to swell and dissolve in the organic electrolyte, it cannot play a good role in bonding the active material to the current collector;
[0005] (2) PVDF is very easy to crystallize due to its high molecular chain regularity, and crystallization will make its ductility worse, and it is easy to form holes in the electrode during the molecular movement, which increases the porosity of the electrode;
[0006] (3) The PVDF binder is always inert during the electrochemical reaction of lithium-sulfur batteries. It has no adsorption capacity for polysulfides at all, and cannot inhibit the shuttle effect of polysulfides in lithium-sulfur batteries.
How to use PVDF and PU in combination to obtain an active binder that not only has the ability to bond but also can inhibit polysulfides, there is no report in this regard

Method used

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  • Composite binder for lithium-sulfur battery and preparation method thereof
  • Composite binder for lithium-sulfur battery and preparation method thereof
  • Composite binder for lithium-sulfur battery and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0066] Step (1) Add PVDF (analytical grade (A.R.), Beijing Institute of Nonferrous Metals) into N-methylpyrrolidone (NMP), and stir to prepare a uniform and stable PVDF solution with a mass fraction of 3%;

[0067] Step (2) adding polyester-type PU (Mw=~26,0000, branched structure) into N,N-dimethylformamide (DMF), stirring to prepare a uniform and stable PU solution with a mass fraction of 3%;

[0068] Step (3) Mix the above PVDF solution and PU solution according to the PVDF:PU mass ratio of 9:1, and then mix them in a constant temperature magnetic stirrer at room temperature for more than 48 hours to obtain a uniform and stable composite bonded lithium sulfur battery. Agent, recorded as PVDF-PU-91.

[0069] Step (4) Use acetylene black (AB) as the sulfur (S) carrier, mix and grind for 30 minutes according to the AB:S mass ratio of 3:7, and then treat it in a muffle furnace at 155°C for 10 hours to obtain the active material AB -70S.

[0070] Step (5) uses the active mater...

Embodiment 2

[0077] Step (1) Add PVDF (analytical grade (A.R.), Beijing Institute of Nonferrous Metals) into N-methylpyrrolidone (NMP), and stir to prepare a uniform and stable PVDF solution with a mass fraction of 3%;

[0078] Step (2) adding polyester-type PU (Mw=~26,0000, branched structure) into N,N-dimethylformamide (DMF), stirring to prepare a uniform and stable PU solution with a mass fraction of 3%;

[0079] Step (3) Mix the above PVDF solution and PU solution according to the PVDF:PU mass ratio of 8:2, and then mix them in a constant temperature magnetic stirrer at room temperature for more than 48 hours to obtain a uniform and stable composite bonded lithium sulfur battery. Agent, recorded as PVDF-PU-82.

[0080] Step (4) Use acetylene black (AB) as the sulfur (S) carrier, mix and grind for 30 minutes according to the AB:S mass ratio of 3:7, and then treat it in a muffle furnace at 155°C for 10 hours to obtain the active material AB -70S.

[0081] Step (5) uses the active mater...

Embodiment 3

[0089]Step (1) Add PVDF (analytical grade (A.R.), Beijing Institute of Nonferrous Metals) into N-methylpyrrolidone (NMP), and stir to prepare a uniform and stable PVDF solution with a mass fraction of 3%;

[0090] Step (2) adding polyester-type PU (Mw=~26,0000, branched structure) into N,N-dimethylformamide (DMF), stirring to prepare a uniform and stable PU solution with a mass fraction of 3%;

[0091] Step (3) Mix the above PVDF solution and PU solution according to the PVDF:PU mass ratio of 7:3, and then mix them in a constant temperature magnetic stirrer at room temperature for more than 48 hours to obtain a uniform and stable composite bonded lithium-sulfur battery. Agent, recorded as PVDF-PU-73.

[0092] Step (4) Use acetylene black (AB) as the sulfur (S) carrier, mix and grind for 30 minutes according to the AB:S mass ratio of 3:7, and then treat it in a muffle furnace at 155°C for 10 hours to obtain the active material AB -70S.

[0093] Step (5) uses the active materi...

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Abstract

The invention relates to a composite binder for a lithium-sulfur battery and a preparation method thereof, and belongs to the field of chemical energy storage batteries. The binder is composed of PVDF(polyvinylidene fluoride) and PU (polyurethane), wherein PU is polyester polyurethane with a branched structure. If the total mass of the binder is 100%, the mass friction of PU is 10-30%, and the rest is PVDF. According to the method, a PVDF solution and a PU solution are mixed according to the proportion that PU occupies 10-30% of the total mass of PVDF and PU, and the mixture is stirred for more than two days to obtain the binder. The addition of PU enables PVDF with strong crystallinity to lose part of the crystalline state, thereby enabling the part where pores should appear to become compact, and maintaining the stability of the electrode structure. In addition, a polar functional group in PU inhibits the dissolution and diffusion of a polysulfide, thereby enabling the target binderto be excellent in electrode performance. The method is simple to operate, and the process and technology are easy to implement.

Description

technical field [0001] The invention relates to a composite binder for lithium-sulfur batteries and a preparation method thereof, belonging to the field of chemical energy storage batteries. Background technique [0002] With the serious environmental pollution caused by fossil fuel combustion and the situation that fossil energy is about to be exhausted, human beings have shifted their attention to more green and clean energy. However, the overcapacity and large-scale abandonment of clean energy require energy storage. The most widely used means of energy storage is the well-known battery. Due to its high volumetric energy density, lithium-ion batteries have been used in many applications in recent years, and it can be said that they have occupied the entire energy storage electronics market, such as lithium cobalt oxide batteries. However, the energy density of lithium-ion batteries has almost reached its theoretical energy density, but it still cannot meet human requirem...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/62
CPCH01M4/622H01M4/623Y02E60/10
Inventor 卢赟刘兴兴苏岳锋陈来赵双义贾盈娜姚金雨包丽颖王敬黄擎陈实吴锋
Owner BEIJING INSTITUTE OF TECHNOLOGYGY
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