A simple method to improve the cycle stability of carbon-sulfur composite lithium-sulfur cathode

A cycle stability and carbon-sulfur composite technology, applied to battery electrodes, lithium batteries, structural parts, etc., can solve the problems of reducing S utilization rate, complicated procedures, and high cost, so as to suppress the impact of capacity and improve cycle performance , the effect of improving the utilization rate

Active Publication Date: 2019-03-05
DALIAN UNIV OF TECH
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Problems solved by technology

However, the S cathode of lithium-sulfur batteries severely restricts its practical application.
The defects of the S cathode are: (1) polysulfide Li 2 S x (2
However, although carbon materials can effectively improve the utilization rate of S single substance, physical adsorption alone cannot improve the cycle stability of the electrode to a satisfactory level. Modifications, such as doping N, compounding with various polar oxides, etc., are costly and complicated

Method used

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  • A simple method to improve the cycle stability of carbon-sulfur composite lithium-sulfur cathode
  • A simple method to improve the cycle stability of carbon-sulfur composite lithium-sulfur cathode
  • A simple method to improve the cycle stability of carbon-sulfur composite lithium-sulfur cathode

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Effect test

Embodiment example 1

[0019] 1) Preparation of core-shell structure carbon / sulfur composite cathode materials

[0020] Add 1.4ml of ammonia water, 55ml of ethanol, 140ml of deionized water, 1.3g of resorcinol, and 1.3g of CTAB into a round bottom flask and stir for 30min. Then add 7.0ml TEOS and 2.0ml formaldehyde, stir at room temperature for 24h, then stand in an oil bath at 100°C for 24h. The reaction product was obtained by suction filtration, dried in a thermostat at 70°C for 12 hours, and the dried product was carbonized at 700°C for 3 hours under the protection of nitrogen, and the obtained product was further etched in 4mol / L NaOH at 80°C for 10 hours to remove SiO 2 ball. The porous hollow carbon spheres obtained after washing the etched product (removing NaOH) and suction-filtering and drying are carbon materials.

[0021] Grind 0.1 of the prepared carbon material and 0.23 g of sublimed sulfur in an agate ball mill to obtain a carbon-sulfur mixture, which is then placed in an ampoule an...

Embodiment example 2

[0032] 1) Preparation of carbon nanotube / sulfur composite cathode material 1:1.4~2.9

[0033] Grind 0.1 of the prepared commercial carbon nanotubes and 0.14 of the sublimated sulfur in an agate ball mill to obtain a carbon-sulfur mixture, which is then placed in an ampoule and melted and sealed with an alcohol blowtorch. The sealed ampoule was placed in a vacuum drying oven, and calcined at 155° C. for 5 hours to obtain a lithium-sulfur battery positive electrode material with a porous core-shell structure sulfur-carbon composite material.

[0034] 2) Preparation of core-shell structure carbon / sulfur composite cathode sheet

[0035] Dissolve the prepared lithium-sulfur battery cathode material, carbon black (conductive agent) and PVDF (binder) in an appropriate amount of NMP according to the mass ratio of 8:1:1 and mix uniformly to prepare the cathode slurry, and coat the cathode with a coating machine. The slurry is coated on the aluminum foil current collector, dried in vac...

Embodiment example 3

[0039] 1) Preparation of graphene / sulfur composite cathode material

[0040]0.1 prepared commercial graphene, 0.29 sublimated sulfur, and ground in an agate ball mill to obtain a carbon-sulfur mixture, which was then placed in an ampoule, melted and sealed with an alcohol blowtorch. Put the sealed ampoule bottle into a vacuum drying oven, and calcinate at 155° C. for 8 hours to obtain a lithium-sulfur battery cathode material with a porous core-shell structure sulfur-carbon composite material.

[0041] 2) Preparation of core-shell structure carbon / sulfur composite cathode sheet

[0042] Dissolve the prepared lithium-sulfur battery positive electrode material, carbon black (conductive agent) and PVDF (binder) in an appropriate amount of NMP according to the mass ratio of 8:1:1 and mix them evenly to prepare positive electrode slurry, and use a coating machine to coat the positive electrode The slurry is coated on the aluminum foil current collector, dried in vacuum at 80°C for...

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Abstract

The invention belongs to the field of lithium-sulfur batteries and discloses a simple method for effectively improving the cycling stability of a carbon-sulfur composite lithium-sulfur cathode. The method comprises the following steps: (1) preparing a core-shell-structured carbon-sulfur composite cathode material; (2) preparing a carbon-sulfur composite cathode piece; and (3) preparing a solid electrolyte membrane (SEI)-coated carbon-sulfur composite electrode. The method has the beneficial effects that (1) polysulfides can be effectively limited in the cathode material by the stable solid electrolyte membrane formed on the surface of the carbon-sulfur composite electrode, so that the capacity influence caused by a shuttle effect can be effectively inhibited, and the cycling performance of the carbon-sulfur composite cathode can be remarkably improved; and (2) by virtue of high conductivity of a carbon material, the utilization rate and rate capability of sulfur are effectively improved, and the charging and discharging of the cathode under high current density are guaranteed.

Description

technical field [0001] The invention belongs to the field of lithium-sulfur batteries, and relates to a simple method for effectively improving the cycle stability of a carbon-sulfur composite lithium-sulfur positive electrode. Background technique [0002] In recent years, lithium-sulfur batteries have been widely used due to their extremely high theoretical capacity (2600Wh·kg -1 ) has received extensive attention and research. However, the S cathode of lithium-sulfur batteries severely restricts its practical application. The defects of the S cathode are: (1) the polysulfide Li 2 S x (2<x<8) dissolves and migrates in the electrolyte solution, which seriously damages the cycle stability of Li-S batteries; (2) the conductivity of sulfur element and low sulfide is very poor, which seriously reduces the utilization rate of S. [0003] At present, researchers have adopted various strategies to solve the above-mentioned problems, including designing new cathode materi...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/587H01M4/62H01M10/052
CPCH01M4/366H01M4/38H01M4/587H01M4/625H01M10/052Y02E60/10
Inventor 张凤祥郭峻岭杜新宇张小龙
Owner DALIAN UNIV OF TECH
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