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Composite lithium-sulfur battery diaphragm as well as preparation method and application thereof

A lithium-sulfur battery, composite technology, applied in the direction of lithium batteries, battery components, non-aqueous electrolyte batteries, etc., can solve the problems of low lithium ion conductivity, poor thermal dimensional stability, size shrinkage, etc., to improve Coulombic efficiency and cycle stability, practicality, and precise thickness and pore size effects

Pending Publication Date: 2021-04-27
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, limited by the film-forming method of polyolefin materials, the porosity of polyolefin separators is generally lower than 40%. Using it as a modified base film will inevitably cause the problem of low lithium ion conductivity in lithium-sulfur batteries.
In addition, the thermal dimensional stability of the polyolefin separator is poor, and there will be significant dimensional shrinkage when the temperature is higher than 120 ° C, resulting in a short circuit inside the battery

Method used

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  • Composite lithium-sulfur battery diaphragm as well as preparation method and application thereof
  • Composite lithium-sulfur battery diaphragm as well as preparation method and application thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0040] 1. Preparation method

[0041] (1) Add equimolar amounts of pyromellitic dianhydride (PMDA) (7.634g, 0.035mol) and 4,4'-diaminodiphenyl ether (ODA) (7.004g, 0.035mol) monomers to the In N-methylpyrrolidone, the monomer concentration is controlled to be 15wt%, and reacted in an ice-water bath for 16 hours to obtain a light yellow transparent and uniform PAA spinning solution; the needle-free electrospinning technology is adopted, and the electrospinning parameters are controlled at The wire voltage was 60 kV, the spinning environment temperature was 15° C., the air relative humidity in the spinning environment was 38%, and the receiving distance was 13 cm to obtain a PAA nanofiber porous membrane. The PAA nanofibrous porous membrane was converted into a polyimide (PI) nanofibrous porous membrane using a temperature-programmed thermal imidization method. The PAA nanofiber porous membrane was heat-treated at 100 °C, 200 °C and 300 °C for 1 h to fully imidize it. The obta...

Embodiment 2

[0048] 1. Preparation method

[0049] (1) Dissolve 5g of aramid fiber in 45g of N,N-dimethylformamide (DMF) solvent, add 0.1g of lithium chloride (LiCl) as a co-solvent, stir at 80°C for 5h, and obtain a transparent and uniform spinning solution; Using the needle-free electrospinning technology, the electrospinning parameters are controlled at a spinning voltage of 50kV, the spinning ambient temperature is 25°C, the relative humidity of the air in the spinning environment is 35%, and the receiving distance is 15cm to obtain a nanofiber porous membrane. The nanofiber porous membrane has a porosity of 75%, a pore diameter of 0.5 μm, and a thickness of 8 μm.

[0050] (2) dissolving piperazine in high-purity water to obtain a water phase monomer solution, the mass fraction of the water phase monomer is 0.1%, dissolving benzenetricarboxylic acid chloride in n-hexane to obtain an oil phase monomer solution, the mass fraction of the oil phase monomer The score is 0.5%. The nanofibe...

Embodiment 3

[0055] 1. Preparation method

[0056] (1) Dissolve 8g of aramid fiber in 45g of N,N-dimethylformamide (DMF) solvent, add 0.4g of lithium chloride (LiCl) as a co-solvent, and stir at 90°C for 2h to obtain a transparent and uniform spinning solution; Needle-type electrospinning technology is adopted, and the electrospinning parameters are controlled at a needle nozzle aperture of 0.6mm, a spinning voltage of 22kV, a receiving distance of 15cm, a spinning rate of 1.2mL / h, a spinning ambient temperature of 25°C, and a spinning air The relative humidity was 40%, and the nanofiber porous membrane was obtained. The obtained nanofiber porous membrane had a porosity of 76%, a pore diameter of 1 μm, and a thickness of 50 μm.

[0057] (2) dissolving piperazine in high-purity water to obtain a water phase monomer solution, the mass fraction of the water phase monomer is 0.1%, dissolving benzenetricarboxylic acid chloride in n-hexane to obtain an oil phase monomer solution, the mass fracti...

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Abstract

The invention provides a composite lithium-sulfur battery diaphragm as well as a preparation method and application thereof. The composite lithium-sulfur battery diaphragm mainly solves the problem of low lithium ion conductivity of a lithium-sulfur battery caused by functional modification of a conventional polyolefin diaphragm in the prior art, and comprises a temperature-resistant nano-fiber porous membrane and an ultrathin separation layer on the surface of the temperature-resistant nano-fiber porous membrane. The composite lithium-sulfur battery diaphragm is characterized in that the porosity of the temperature-resistant nano-fiber porous membrane is 75-95%, the pore diameter is 0.5-2 mum, and the thickness is 8-50 mum; and the pore diameter of the ultrathin separation layer is 0.3 nm-1 nm, and the thickness of the ultrathin separation layer is 50-100 nm. According to the technical scheme, the problems are better solved, the method is easy to popularize, the industrial application of the lithium-sulfur battery is favorably accelerated, and the diaphragm can be applied to the industrial application of the lithium-sulfur battery.

Description

technical field [0001] The invention belongs to the technical field of battery materials, and relates to a composite lithium-sulfur battery separator and its preparation method and application. Background technique [0002] Lithium-sulfur batteries use elemental sulfur with high specific capacity as the positive electrode material, and its theoretical energy density can reach 2600 Wh kg -1 . At the same time, elemental sulfur also has the advantages of abundant reserves, cheap price, and environmental friendliness. Therefore, lithium-sulfur batteries are considered to be a new battery system with great research value and development potential. However, polysulfides (Li 2 S x (x=4-8)) are easily dissolved in the electrolyte. The dissolved high-valence polysulfides will migrate to the metal lithium negative electrode under the action of concentration gradient and react with it, converting into short-chain polysulfides; the short-chain polysulfides will diffuse back to the...

Claims

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Application Information

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IPC IPC(8): H01M50/403H01M50/414H01M50/44H01M50/449H01M50/489H01M50/491H01M50/497H01M10/052
CPCH01M10/052Y02E60/10
Inventor 张宏陈雪崔晶张培斌孙旭阳
Owner CHINA PETROLEUM & CHEM CORP