Production method of boron nitride coated diaphragm of lithium-sulfur battery

A technology of boron nitride packs and lithium-sulfur batteries, which is applied in the direction of lithium batteries, battery components, non-aqueous electrolyte batteries, etc., can solve the problem of hindering the discharge reaction between electrolytes and electrode active materials, reducing battery Coulombic efficiency and cycle life, and preparing The method is unfavorable for promotion and universalization, and achieves the effects of suppressing the shuttle effect, ensuring cycle stability, and avoiding overcharging.

Active Publication Date: 2015-10-21
NORTHWESTERN POLYTECHNICAL UNIV
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AI Technical Summary

Problems solved by technology

First of all, a large amount of polysulfide anions will dissolve and diffuse in the electrolyte, which will lead to the loss of the active material of the positive electrode. At the same time, it will shuttle the diaphragm many times to react with the discharge product of the negative electrode, causing the "shuttle effect" and causing the battery to overcharge. The coulombic efficiency and cycle life of the battery; secondly, the discharge product lithium sulfide will precipitate from the organic electrolyte and cover the surface of the sulfur positive electrode to form an insulating lithium sulfide film, thereby hindering the discharge between the electrolyte and the electrode active material reaction
[0006] (2) The chemical properties of metal lithium are very active, and it is easy to react with the electrolyte solution, and an SEI film is formed on the surface of the electrode material, resulting in an increase in the polarization resistance of the electrode; the dissolved high-polymer polysulfide will diffuse to the lithium surface and form a self-reaction with lithium. The discharge corrosion reaction leads to irreversible capacity loss of the active material; at the same time, the reduction product of some oligomerization states diffuses back to the positive electrode under the action of the concentration gradient for re-oxidation, resulting in the shuttle effect and reducing the electric Coulombic efficiency
However, it is worth noting that the copper foil-lithium-boron nitride "sandwich structure" proposed in this article uses copper as a current collector to improve the lithium negative electrode, and does not investigate the dendrites and deposition when metal lithium is used as the negative electrode. At the same time, the chemical vapor deposition and electrochemical deposition methods used in the article are relatively cumbersome, and the experimental conditions are relatively harsh. Such a complicated preparation method is not conducive to popularization and universalization, and still needs further improvement

Method used

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  • Production method of boron nitride coated diaphragm of lithium-sulfur battery
  • Production method of boron nitride coated diaphragm of lithium-sulfur battery
  • Production method of boron nitride coated diaphragm of lithium-sulfur battery

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0039] Take a piece of Celgard 2325 diaphragm, use MSK-T10 button cell slicer to cut into a disc with a diameter of 19mm, put it in a beaker, use acetone, isopropanol and ethanol to clean it ultrasonically, and then use deionized water Rinse and dry. Take 1 mg of hexagonal boron nitride powder, dissolve it in 50 mL of N-methylpyrrolidone, stir it thoroughly, and sonicate it for 24 hours. After sonication, the solution was transferred to a centrifuge tube and centrifuged at 500 rpm for 10 min. Add 1 mg of polyvinylidene fluoride to the supernatant after centrifugation, and stir thoroughly to obtain boron nitride slurry. Place the washed diaphragm on a flat glass bottom plate, pour the slurry on the diaphragm, and use a four-sided film applicator to manually coat the film with a film thickness of 25um; after drying at 50°C, coat the reverse side of the diaphragm again. After drying again, a boron nitride-coated diaphragm is obtained.

Embodiment 2

[0041] Take a piece of Celgard 2325 diaphragm, use MSK-T10 button cell slicer to cut into a disc with a diameter of 19mm, put it in a beaker, use acetone, isopropanol and ethanol to clean it ultrasonically, and then use deionized water Rinse and dry. Take 5 mg of hexagonal boron nitride powder, dissolve it in 50 mL of N-methylpyrrolidone, stir it thoroughly, and ultrasonicate for 24 hours. After the sonication, the solution was transferred to a centrifuge tube and centrifuged at 1000rpm for 30min. After centrifugation, 3 mg of polyvinylidene fluoride was added to the supernatant, and the boron nitride slurry was obtained after thorough stirring. Take 50mL of the prepared slurry and place it in a beaker, grab a piece of diaphragm with tweezers, soak it in the beaker for 30s, then take it out and let it stand in the air for 60s, put the diaphragm in a drying oven to dry, and then the nitrided Boron coated diaphragm.

Embodiment 3

[0043] Take a piece of Celgard 2325 diaphragm, use MSK-T10 button cell slicer to cut into a disc with a diameter of 19mm, put it in a beaker, use acetone, isopropanol and ethanol to clean it ultrasonically, and then use deionized water Rinse and dry. Take 5 mg of hexagonal boron nitride powder, dissolve it in 100 mL of N-methylpyrrolidone, stir it thoroughly, and ultrasonicate for 24 hours. After the sonication, the solution was transferred to a centrifuge tube and centrifuged at 3000rpm for 30min. Add 1 mg of polyvinylidene fluoride to the supernatant after centrifugation, and stir thoroughly to obtain boron nitride slurry. Take a diaphragm and fix it on the substrate of the spin coater, adjust the speed of the spin coater to 60rpm, slowly inject the boron nitride slurry from the liquid injection port at a uniform speed, then adjust the speed of the spin coater to 300rpm, wait for the spin coating to be uniform, and take the diaphragm out Next, dry. Then spin-coat the reve...

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Abstract

The invention relates to a production method of a boron nitride coated diaphragm of a lithium-sulfur battery. The diaphragm is produced from a commercial polypropylene diaphragm, two sides of the diaphragm are uniformly covered with hexagonal boron nitride, and the characteristics of hexagonal boron nitride 'white graphite' are used, so lithium ions are allowed to pass, shuttle of polysulfide anions is obstructed, a reaction of a lithium negative electrode with the polysulfide anions is inhibited, formation of lithium dendrites, lithium sulfide precipitate and fixed lithium is prevented, the capacity, the coulombic efficiency and the cycle stability of the lithium-sulfur battery are improved, the growth of the negative electrode metal dendrite in the cycle process is effectively inhibited, and the safety of the battery is improved. The method has the advantages of simple process route and clear purpose, and the produced diaphragm has multiple functions, and can greatly overcome disadvantages of present technologies.

Description

technical field [0001] The invention relates to the field of lithium-ion batteries, in particular to a multifunctional boron nitride-coated separator for lithium-sulfur batteries and a preparation method thereof. Background technique [0002] Since the Italian Alessandro Volta invented the world's first battery in 1799, after more than 200 years of development, the types and output of chemical power sources have been continuously updated and expanded, and the occasions and application ranges are also increasing. It is one of the essential sources of energy and power in production activities. With the rapid development of space technology, mobile communications, missiles, aerospace and other fields, as well as the increasing concern of modern people on energy crisis and environmental protection issues, the research and development of lithium secondary batteries with high energy density has aroused widespread interest. The main reason for the low energy density of existing se...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M2/16H01M2/14H01M50/403H01M50/417
CPCH01M10/052H01M50/446H01M50/403Y02E60/10
Inventor 韩昀钊谢科予魏秉庆
Owner NORTHWESTERN POLYTECHNICAL UNIV
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