Method for preparing reduced graphene oxide load ReS2 for cathode material of lithium sulfur battery

A cathode material, lithium-sulfur battery technology, used in nanotechnology for materials and surface science, battery electrodes, lithium batteries, etc. problem, to achieve the effect of improving cycle stability, good electrical conductivity, and improving electrical conductivity

Inactive Publication Date: 2019-03-29
TIANJIN UNIV
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Problems solved by technology

However, the sulfur cathode has the following problems: first, during the discharge process, sulfur will be reduced to lithium sulfide, and the process will undergo multi-step reduction reactions, undergoing solid-liquid-solid transformation, and generate a variety of long-chain lithium polysulfides (Li 2 S x , 4≤x≤8) and then reduced to Li 2 S 2 and Li 2 S, in which the long-chain lithium polysulfide is easily dissolved in the ether electrolyte, resulting in the loss of active materials, resulting in capacity decay and poor cycle stability
Among them, carbon materials mainly include porous carbon, hollow carbon spheres, graphene, carbon nanotubes, carbon nanofibers, etc., which mainly bind lithium polysulfide through physical adsorption, and the excellent conductivity of carbon materials also makes up for the sulfur The disadvantage of poor conductivity, but the binding force between non-polar carbon and polar lithium polysulfide is van der Waals force, which is a weak combination, so it cannot effectively inhibit the dissolution and diffusion of lithium polysulfide

Method used

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  • Method for preparing reduced graphene oxide load ReS2 for cathode material of lithium sulfur battery
  • Method for preparing reduced graphene oxide load ReS2 for cathode material of lithium sulfur battery
  • Method for preparing reduced graphene oxide load ReS2 for cathode material of lithium sulfur battery

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preparation example Construction

[0023] rGO / ReS of the present invention 2 The preparation of graphene oxide was used as the substrate, and ReS was grown on graphene oxide by hydrothermal method. 2 At the same time, graphene oxide can be reduced, and the product obtained by hydrothermal treatment can be calcined to obtain rGO / ReS 2 composite material. In the battery system, it can be applied to the positive electrode of lithium-sulfur battery by mixing and calcining with sulfur. The specific process is as follows:

[0024] 1) Preparation of graphene oxide dispersion

[0025] Weigh 25-60 mg of commercial single-layer graphene oxide powder, add it to deionized water, the concentration of graphene oxide solution is 1.2-2 mg / ml, stir well, add 10-60 mg hexadecyl trimethyl bromide ammonium chloride (CTAB), put it into an ultrasonic cleaner for 1-4h to make it evenly dispersed, and then keep stirring for 1-4h.

[0026] 2) Preparation of reduced graphene oxide supported ReS 2 Nanosheets

[0027] Add ammonium ...

Embodiment 1

[0034] (1) Prepare graphene oxide dispersion liquid. Weigh 60 mg of commercial single-layer graphene oxide powder, add it to deionized water, so that the concentration of the graphene oxide solution is 2 mg / ml, after stirring evenly, add 40 mg cetyltrimethylammonium bromide (CTAB) , put it into an ultrasonic cleaner for 2 hours to make it dispersed evenly, and then continue to stir for 2 hours.

[0035] (2) Preparation of reduced graphene oxide supported ReS 2 Nanosheets. Weigh 30mg of ammonium perrhenate, add 60mg of thiourea to the graphene oxide dispersion prepared in step 1, stir magnetically for 3 hours to make it evenly mixed, and move the mixed solution to a stainless steel reaction kettle with a polytetrafluoroethylene liner of 50ml Then put it into a vacuum drying oven and heat it to 220°C, react for 24 hours, wait for the reaction kettle to cool down to room temperature, centrifuge to collect the reaction product in the inner tank of the reaction kettle, wash it wi...

Embodiment 2

[0041] The difference from Example 1 is: (1) preparing a graphene oxide dispersion. Weigh 60 mg of commercial single-layer graphene oxide powder, add it to deionized water to make the concentration of graphene oxide solution 2 mg / ml, after stirring evenly, put it into an ultrasonic machine for 2 h to disperse evenly, then continue stirring for 2 h . The rest are the same as in Embodiment 1, and will not be repeated here.

[0042] The resulting material is compared with Example 1, ReS 2 It is a nanosphere, which cannot be well combined with the reduced graphene oxide, and the distribution is uneven, which will lead to a decrease in the specific surface area of ​​the material, slow down the reaction kinetics, and also lead to a decrease in the loading of the active substance sulfur.

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Abstract

The invention relates to a method for preparing reduced graphene oxide load ReS2 for a cathode material of a lithium sulfur battery. The method comprises steps that 1), graphene oxide dispersion is prepared through utilizing single-layer graphene oxide powder; preparation of reduced graphene oxide-loaded ReS2 nanosheet, according to the mass ratio of ammonium perrhenate and thiourea and the single-layer graphene oxide powder (0.3-0.7) ): (0.8-1.2): 1, the ammonium perrhenate and thiourea are weighed and added to the graphene oxide dispersion to obtain uniform mixture solution, the mixture solution is transferred to a reaction vessel and then heated to 150-240 DEG C for 10-24 hours, and a reaction product is obtained; the reduced graphene oxide load ReS 2 nanosheet is calcined to improve the crystallinity of the material, and the final product rGO / ReS2 is obtained.

Description

technical field [0001] The invention belongs to the technical field of electrode materials for lithium-sulfur batteries, and in particular relates to a reduced graphene oxide-loaded ReS used for lithium-sulfur battery positive electrodes, which can effectively inhibit the dissolution of lithium polysulfide, accelerate reaction kinetics, and inhibit sulfur volume expansion. 2 Preparation method of composite sulfur cathode. Background technique [0002] With the aggravation of energy crisis and environmental pollution, it is imminent to develop clean energy such as solar energy and wind energy and effectively collect and utilize them. However, the specific capacity of the current commercial lithium-ion battery cathode materials is limited by its intercalation and extraction mechanism, and it is difficult to meet the demand for high energy density. Therefore, the development of new alternative cathode materials is the current research focus of secondary batteries. The sulfur c...

Claims

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Application Information

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IPC IPC(8): H01M4/36H01M4/38H01M4/58H01M4/62H01M10/052B82Y30/00
CPCB82Y30/00H01M4/362H01M4/38H01M4/5815H01M4/625H01M4/628H01M10/052Y02E60/10
Inventor 刘华雄师春生赵乃勤刘恩佐何春年何芳
Owner TIANJIN UNIV
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