Carbon sulfur composite material for lithium-sulfur battery and preparation method and application for carbon sulfur composite material

A composite material, lithium-sulfur battery technology, applied in the field of electrochemical batteries, can solve the problems of active material loss, active material content reduction, increase inactive materials, etc., to achieve high electrolyte absorption capacity, high specific energy density, good conductivity network effect

Inactive Publication Date: 2016-03-30
THE NAT CENT FOR NANOSCI & TECH NCNST OF CHINA
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, coating the composite layer on the separator is likely to cause a short circuit in the battery, while coating the composite layer on the surface of the positive electrode will easily destroy the original void structure on the electrode surface, and the coating method will inevitably introduce an inactive material coating layer. , so that the content of active materials in the battery is reduced, which is not conducive to the realization of the characteristics of high specific energy density of lithium-sulfur batteries
In addition, the patent CN103050667A discloses a multi-layer structure composite positive electrode for lithium-sulfur secondary batteries and its preparation method. It mentions the method of using sputtering to load a layer of conductive film on the surface of the positive electrode of lithium-sulfur batteries, but this method is relatively Complex, high cost, does not take advantage of large-scale mass production
[0004] In summary, although the existing methods can improve the performance of lithium-sulfur batteries to a certain extent, by simply increasing the intermediate layer material or directly coating the intermediate layer on the surface of the positive electrode, the total inactive substances of the battery are increased. The quality of the battery will reduce the proportion of active materials in the battery, which is not conducive to the realization of the characteristics of high specific energy density of lithium-sulfur batteries; in addition, the dissolution of active sulfur will inevitably enter the middle layer during the discharge process, causing further loss of active materials, making the initial rapid decline in battery capacity. attenuation

Method used

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  • Carbon sulfur composite material for lithium-sulfur battery and preparation method and application for carbon sulfur composite material
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  • Carbon sulfur composite material for lithium-sulfur battery and preparation method and application for carbon sulfur composite material

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Embodiment 1

[0037] After the bacterial cellulose was fully washed in deionized water, it was quickly frozen with liquid nitrogen, and then placed in a vacuum oven at -50°C and 20.0 Pa to remove all moisture. Subsequently, the obtained bacterial cellulose aerogel was placed in an atmosphere tube furnace and heated at 5 °C min under the protection of Ar gas. -1 The heating rate was increased to 800°C for high-temperature carbonization, and after 1 hour of heat preservation, it was cooled with the furnace to prepare carbonized bacterial cellulose.

[0038] Dissolve different masses of Huahua sulfur in the carbon disulfide solution to prepare the concentrations of 20 mg·mL -1 , 15mg·mL -1 , 8mg·mL -1 , 5mg·mL -1 and 0.5mg·mL -1 solution of sulfur in carbon disulfide. Immerse the carbonized bacterial cellulose in solutions of different concentrations, take it out after soaking for 1 hour, dry it in a fume hood, place it in an oven, keep it at a constant temperature of 155°C for 12 hours, ...

Embodiment 2

[0041] 1 g of lignocellulose was dispersed in 100 mL of an aqueous solution of TEMPO (0.016 g) and NaBr (0.016 g). Another part of 12 wt% NaClO aqueous solution was prepared, and HCl solution was added to adjust its pH value to 10. A certain amount of NaClO solution was added to the lignocellulose dispersion so that the ratio of NaClO to cellulose was 3 mmol NaClO: 1 g cellulose. The resulting solution was stirred at room temperature and the pH was controlled at 10 with NaOH solution. TEMPO-mediated cellulose oxidation ends when NaOH is no longer consumed. Subsequently, the oxidized cellulose was washed with deionized water through suction filtration, and then dispersed in water. The oxidized cellulose dispersion is subjected to vacuum filtration to prepare a lignocellulose film. The obtained lignocellulose film was placed in an atmosphere tube furnace at 5 °C min under the protection of Ar gas. -1 The heating rate was increased to 800°C for high-temperature carbonization,...

Embodiment 3

[0045] The multi-walled carbon nanotubes were added into an aqueous solution with a volume ratio of concentrated sulfuric acid and concentrated nitric acid of 3:1, and oxidized by heating and refluxing at 80° C. for 12 hours. Subsequently, the suspension is diluted with deionized water and centrifugally cleaned, and the final product is ultrasonically dispersed in a certain amount of deionized water to obtain a carbon nanotube dispersion.

[0046] Sodium sulfide (Na 2 S) be dissolved in deionized water, after forming a solution, add sublimation sulfur, control Na 2 The molar ratio of S to sublimed sulfur was 1:3, and stirred at room temperature for 2 h. Subsequently, slowly add acetic acid (CH 3 COOH) to pH=3, the reaction generates sulfur particle precipitation. After the precipitate was taken out by centrifugation, it was washed three times with deionized water and dispersed by ultrasonic to obtain a sulfur suspension.

[0047]The carbon nanotube dispersion and the sulfu...

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Abstract

The invention provides a carbon sulfur composite material for a lithium-sulfur battery and a preparation method and an application for the carbon sulfur composite material. The carbon sulfur composite material is positioned between a positive electrode and a diaphragm of the lithium-sulfur battery. For solving the problems of severe circulation capacity degradation, low active substance conductivity and the like of the lithium-sulfur battery, the carbon sulfur composite material positioned between the positive electrode and the diaphragm is designed and prepared and is used for improving the electrochemical performance of the lithium-sulfur battery; the capability of the material for absorbing and holding polysulfide ions can be adjusted by controlling the content of sulfur in the carbon sulfur composite material to improve the utilization rate of sulfur so as to improve the charge-discharge capacity and the cycling performance of the lithium-sulfur battery; and in addition, the carbon sulfur composite material provided by the invention is simple and easy to implement the preparation process, and good for later industrial production and quite high in potential in actual applications.

Description

technical field [0001] The invention relates to the technical field of electrochemical batteries, in particular to a carbon-sulfur composite material and its preparation method and application, and in particular to a carbon-sulfur composite material for lithium-sulfur batteries and its preparation method and application. Background technique [0002] Lithium-sulfur batteries are expected to become the next generation of secondary batteries with high energy density, because the positive electrode active material is elemental sulfur, its raw material is cheap, environmentally friendly, and has a specific energy density 3-5 times higher than the current lithium-ion battery system. However, the corrosion of polysulfide ions, an intermediate product dissolved during the electrochemical reaction of lithium-sulfur batteries, on the metal lithium anode, and the accumulation of poorly conductive sulfur and lithium sulfide on the electrode surface lead to serious attenuation of battery...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/587H01M4/62H01M10/0525
CPCH01M4/364H01M4/38H01M4/587H01M4/624H01M4/628H01M10/0525Y02E60/10
Inventor 智林杰张云博苗力孝
Owner THE NAT CENT FOR NANOSCI & TECH NCNST OF CHINA
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