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Composite separator for lithium battery

A composite separator and lithium battery technology, applied in secondary batteries, battery pack parts, secondary battery repair/maintenance, etc., can solve problems such as limited effect, inhibit dendrite growth, prevent battery short circuit, and improve cycle efficiency effect on safety

Active Publication Date: 2018-08-03
TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] Although the above research ideas can improve the high temperature stability and mechanical properties of lithium battery separators, they have limited effect on guiding the uniform distribution of lithium ions in batteries in service.

Method used

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  • Composite separator for lithium battery

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] Embodiment 1: the lithium ion conductor Li 6.75 La 3 Zr 1.75 Ta 0.25 o 12 The nanoparticles are blended with a binder and dissolved in THF. Through suction filtration, the above mixed solution was filtered on a polypropylene (PP) membrane. Dry to obtain a composite separator that can be used for lithium batteries. In the diaphragm, the thickness of the inorganic lithium ion conductor layer is 5 μm, the thickness of the base layer polypropylene is 25 μm, and the thickness of the composite diaphragm is 30 μm. The ion conductivity of the inorganic lithium ion conductor material at room temperature is 1.5×10 -4 S cm -1 . The composite diaphragm can withstand the working temperature range of 20°C-120°C. The heat shrinkage rate of the composite diaphragm is 3%. The above diaphragm is matched with the positive electrode of lithium iron phosphate and the negative electrode of lithium metal. After performing electrochemical tests, it was found that at room temperature, a...

Embodiment 2

[0026] Embodiment 2: prepare tantalum-doped Li by electrospinning method 7 La 3 Zr 2 o 12 (LLZO) nanowires dispersed in the organic solvent n,n-dimethylformamide (DMF). Through suction filtration, the above mixed solution was filtered on a polypropylene membrane. Dry to obtain a composite separator that can be used for lithium batteries. In the diaphragm, the thickness of the inorganic lithium ion conductor layer is 10 μm, the thickness of the base layer is 25 μm, and the thickness of the composite diaphragm is 35 μm. The ion conductivity of the inorganic lithium ion conductor material LLZO is 9.5×10 at a working temperature of 90°C. -4 S cm -1 . The operating temperature range of the separator is 20°C-120°C. The heat shrinkage rate of the separator is 2%. The above separator is matched with the positive electrode of lithium cobaltate and the negative electrode of graphite. After performing electrochemical tests, it was found that at a high ambient temperature of 90°C, ...

Embodiment 3

[0027] Embodiment 3: use aluminum, tantalum co-doped Li 7 La 3 Zr 2 o 12 (LLZO) bulk target material, sputtering LLZO onto the polypropylene film to obtain a composite separator for lithium batteries. In the separator, the thickness of the inorganic lithium ion conductor layer is 10nm, the thickness of the base layer polypropylene is 25μm, and the thickness of the composite separator is 25μm. The ion conductivity of the inorganic lithium ion conductor material LLZO is 9.5×10 at a working temperature of 90°C. -4 S cm -1 . The operating temperature range of the diaphragm is 20°C-80°C. The heat shrinkage rate of the diaphragm is 4%. The above diaphragm is matched with the positive electrode of lithium cobaltate and the negative electrode of graphite. After performing electrochemical tests, it was found that at a high ambient temperature of 90°C, 3.0mA cm -2 Under the current density, after activation, the capacity attenuation is less than 5% in the range of 500 cycles, and ...

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Abstract

The invention discloses a composite separator for a lithium battery. The composite separator is applicable to a lithium ion battery or a metal lithium battery. The composite separator is formed by combining a substrate layer and an inorganic lithium ion conductor layer, wherein the inorganic lithium ion conductor layer employs an inorganic lithium ion conductor material with lithium ion conductivity larger than 1.0*10<-8>S cm<-1> under a temperature of 20-120 DEG C, the inorganic lithium ion conductor material exists in the substrate layer in a form of one or more of particle, cylinder, pipe and line, the substrate layer provides a basic separator framework, lithium ions can be induced to be uniformly deposited by the lithium ion conductor layer, and the mechanical property and the thermalstability of the separator are improved. The composite separator is simple in preparation method, lithium dendrites growth caused by non-uniform lithium ion distribution can be effectively suppressed, and the cycle efficiency and the safety of the battery within a wide temperature range are greatly improved; and by matching a high-capacity positive / negative electrode material, the cycle lifetimeof the lithium battery can be prolonged, the energy density and the safety of the lithium battery can be improved, and the industrial process is promoted.

Description

technical field [0001] The invention relates to a novel composite diaphragm for lithium batteries, which can be used for lithium ion batteries and metal lithium batteries. Background technique [0002] With the continuous progress of the modern electronics industry, the application range of energy storage devices is becoming wider and wider. As an electrochemical energy storage device, batteries are widely used in many fields such as portable smart devices and electric vehicles. Among many electrode materials, lithium has extremely low density, high capacity, and extremely low electrochemical potential, and lithium batteries are widely used. Since the last century, the commercialization of lithium-ion batteries has been increasing, and lithium iron phosphate, lithium cobaltate, etc. are mostly used as positive electrode materials, and graphite is used as negative electrode materials. It has high energy density, low self-discharge, and no memory effect. It is widely used in...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M2/16H01M10/42H01M50/411H01M50/431H01M50/446H01M50/449
CPCH01M10/4235H01M50/431H01M50/446H01M50/411H01M50/449Y02E60/10
Inventor 张强赵辰孜程新兵
Owner TSINGHUA UNIV
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