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Micro-capsule-structured carbon-sulfur compound and preparation method and application thereof

A composite and microcapsule technology is applied in the field of nanocomposite materials and their preparation, which can solve the problems of reduced utilization rate of elemental sulfur, low utilization rate of sulfur of positive active material, and reduced cycle stability of batteries, and achieves improved cycle stability, Avoid the "shuttle" effect and the effect of low price of raw materials

Active Publication Date: 2017-03-15
DALIAN INST OF CHEM PHYSICS CHINESE ACAD OF SCI
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] Although lithium-sulfur batteries have many advantages, they still remain at the laboratory and small-scale demonstration level so far, and have not really realized large-scale applications.
The main reason is that the utilization rate of sulfur in the positive electrode active material is low, and the cycle capacity decay is serious. The specific performance is: first, the discharge product of the battery is lithium sulfide with low conductivity, which is easy to deposit on the surface of the carbon material, hindering the further reaction of sulfur. Reduce the utilization rate of elemental sulfur; secondly, the intermediate product lithium polysulfide (Li polysulfide) generated in the process of sulfur reduction or lithium sulfide oxidation 2 S n , 3≤n≤6) are all soluble in the electrolyte, and diffuse through the separator to the lithium negative electrode to form insoluble Li 2 S or Li 2 S 2 , causing active material loss and capacity fading (that is, the "shuttle" effect of lithium polysulfide leads to the loss of active material); moreover, due to sulfur (2.07g / cm 3 ) and Li 2 S (1.66g / cm 3 ) has a large difference in density, and significant volume shrinkage and expansion will occur during charging and discharging, thereby destroying the structure of the electrode (carbon-sulfur composite electrode) and reducing the cycle stability of the battery

Method used

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  • Micro-capsule-structured carbon-sulfur compound and preparation method and application thereof
  • Micro-capsule-structured carbon-sulfur compound and preparation method and application thereof
  • Micro-capsule-structured carbon-sulfur compound and preparation method and application thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0045] Take 3.33g of silica particles (particle size 100-200nm) and disperse them in 10g of ethanol, after ultrasonic stirring for 30min, add 10g (20wt%) of phenolic resin ethanol solution, continue stirring for 3h, add 6.66g (24nm, 40wt%) Silica sol, ultrasonically stirred for 2 hours, scraped onto a glass plate, kept in an oven at 100°C for 24 hours, transferred to a tube furnace for calcination under argon gas, kept at 350°C for 3 hours, and kept at 900°C for 5 hours, then sprayed with 10% hydrogen Fluoric acid dissolves and removes the silicon template to obtain a hollow carbon material.

[0046] Dissolve 2g of lithium sulfide powder in ethanol (concentration 20mg / ml), add the above-mentioned hollow carbon material, wash the lithium sulfide on the surface with ethanol after immersion for 1 hour, after repeated immersion for 5 times, dry it in vacuum at 60°C for 10 hours, under argon gas Calcined at 300℃ for 2h to obtain carbon-coated lithium sulfide material.

[0047] Add...

Embodiment 2

[0049] Take 10g of calcium carbonate powder (particle size 300nm) and disperse it in 10g of water, after ultrasonic stirring for 30min, add 10g of gelatin, stir at 70°C for 3h, after ultrasonic stirring for 2h, scrape-coat it on a glass plate, keep the temperature in an oven at 100°C for 24h, transfer to Roasting in a tube furnace under argon gas, constant temperature at 350°C for 3h and 900°C for 5h, dissolve and remove calcium template with 2M hydrochloric acid solution to obtain hollow carbon material.

[0050] Dissolve 8.0035g of lithium sulfide powder in isopropanol (concentration: 3mg / ml), add the above-mentioned hollow carbon material, wash the lithium sulfide on the surface with isopropanol after immersion for 1 hour, repeat the immersion for 5 times, and dry it in vacuum at 60°C for 10 hours , roasted at 300°C for 2h under argon gas to obtain carbon-coated lithium sulfide materials.

[0051] Add 16.7 mg of phosphorus pentasulfide into tetraglyme solution at 60°C (conc...

Embodiment 3

[0053] Take 1g of PVP powder (particle size 100nm) and disperse it in 10g of water, after ultrasonic stirring for 30min, add 1g of furfural, stir at 70°C for 3h, after ultrasonic stirring for 2h, keep the temperature in an oven at 100°C for 24h, transfer to a tube furnace for roasting under argon gas After constant temperature at 350°C for 3h and 900°C for 5h, 0.05g of hollow carbon material was obtained.

[0054] Dissolve 1.0496g of lithium sulfide powder in isopropanol (concentration: 5mg / ml), add the above-mentioned hollow carbon material, wash the lithium sulfide on the surface with isopropanol after immersion for 1 hour, repeat the immersion for 5 times, and then vacuum-dry at 60°C for 10 hours , roasted at 300°C for 2h under argon gas to obtain carbon-coated lithium sulfide materials.

[0055] Add 4.1 g of phosphorus pentasulfide into a diethylene glycol dimethyl ether solution at 60°C (concentration: 5 mg / ml), stir for 3 hours, ultrasonically disperse for 10 hours, and ...

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Abstract

The invention relates to a micro-capsule-structured carbon-sulfur compound and a preparation method and an application thereof. The compound takes lithium sulfide as a capsule-core material, and takes a carbon material and a lithium ion conductor as a capsule-wall material; the capsule-core material is positioned in the hollow capsule-wall material, wherein the capsule-core material is 20-300nm in grain diameter; the capsule wall is 2-50nm in thickness; the content of the capsule-core material accounts for 20-80wt% of the carbon-sulfur compound; and the mass ratio of the carbon material to the lithium ion conductor in the capsule-wall material is (1:99) to (99:1). Based on the structural advantage of the "micro-capsule", a positive electrode material design thought of "capsule core sulfur-carrying, capsule wall sulfur-fixing, hole wall electric conduction and hole channel sold-state lithium conduction" is proposed, so that the utilization rate and the cycling stability of the active material sulfur in a lithium-sulfur battery are greatly improved.

Description

technical field [0001] The invention relates to a nanocomposite material and a preparation method thereof, in particular to a carbon-sulfur compound with a microcapsule structure suitable for the positive electrode of a lithium-sulfur battery and a preparation method thereof. Background technique [0002] With the rapid development of mobile communications, electronic equipment, electric vehicles and space technology, there is an urgent need to develop secondary batteries with high energy density. At present, the actual specific energy of lithium-ion batteries is mostly lower than 200Wh / kg. Due to the limitation of the theoretical specific capacity of the existing positive electrode materials (as shown in Table 1), it is difficult to increase the specific energy, and it relies on high charging voltage to increase the specific energy. The way of energy will exacerbate system security issues, so it is necessary to develop a new generation of electrochemical energy storage syst...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/58H01M4/62H01M10/052B82Y30/00
CPCB82Y30/00H01M4/366H01M4/5815H01M4/625H01M10/052H01M2004/021Y02E60/10
Inventor 王美日张华民张洪章李先锋曲超吴宝山
Owner DALIAN INST OF CHEM PHYSICS CHINESE ACAD OF SCI
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