Three-dimensional graphite aerogel sulfur-carrying composite material as well as preparation method and application thereof

A technology of graphene airgel and composite materials, which is applied in the field of electrode materials for lithium-sulfur batteries, can solve problems such as poor cycle performance and rate performance, unsatisfactory material conductivity, complicated preparation process, etc., and achieve convenient large-scale production , improve cycle stability and rate performance, and alleviate the effect of volume change

Active Publication Date: 2017-06-09

NANJING NORMAL UNIVERSITY

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Problems solved by technology

[0005] However, there are still some defects in the current related technology, such as complex preparation process, high energy consumption in the heating process, and sulfur volatilization, resultin...

Abstract

The invention discloses a three-dimensional graphite aerogel sulfur-carrying composite material as well as a preparation method and application thereof. The preparation method comprises the following steps: forming an aerogel precursor from sulfur and oxidized graphene, and performing reduction by using hydrazine hydrate, thereby obtaining a graphene wrapped sulfur- composite material of three-dimensional network structures of which the interiors are communicated with one another. Compared with the prior art, the composite material disclosed by the invention can be used as an anode material of a lithium-sulfur battery, and has preponderant circulation stability and high rate capability.

Application Domain

Cell electrodes

Technology Topic

High rateCyclic stability +7

Image

Examples

Experimental program(9)

Example Embodiment

[0032] Example 1

[0033] (1) Preparation of three-dimensional graphene oxide aerogel sulfur-supported (S/GO) composite material: Disperse 50 mg of graphene oxide and 50 mg of sublimed sulfur in 5 mL of distilled water, and add 0.5 mL of 10 mg mL at room temperature (25°C) -1 Chitosan (molecular weight: 150,000)/acetic acid aqueous solution (volume ratio of acetic acid to water is 5:95), stir until a hydrogel is formed, and then stand at room temperature for 6 hours, freeze-dry, to obtain three-dimensional graphite oxide Sulfur-loaded olefin aerogel (S/GO) composite material.

[0034] (2) Preparation of three-dimensional graphene aerogel sulfur-supported (S/rGO) composite material: 105 mg of the product obtained in step (1) was dispersed in 5 mL of distilled water, and 0.3 mL of ammonia (25 wt%) and 0.2mL hydrazine hydrate (50wt%) was reacted for 1.5 hours, filtered with suction and washed with distilled water until the filtrate was neutral, and the collected solids were freeze-dried to obtain the three-dimensional graphene aerogel sulfur (S/rGO) composite material.

[0035] figure 1 It is the X-ray diffraction pattern of the S/GO and S/rGO composite material synthesized in this example. It can be seen from the figure that the sulfur in the S/GO and S/rGO composites exists in the crystalline phase of orthorhombic sulfur (JCPDS No.08-0247).

[0036] figure 2 It is the thermogravimetric analysis diagram of the S/rGO composite synthesized in this example. It can be calculated from the figure that the content of S in the S/rGO composite is 50wt%.

[0037] image 3 Is the S/GO synthesized in this example ( image 3 a,b) and S/rGO( image 3 c,d) Scanning electron micrograph of composite material. by image 3 a and image 3 b. It can be seen that the size of sublimed sulfur is not uniform, and graphene oxide is uniformly coated on the surface of sulfur particles to form a three-dimensional network structure. After being reduced by hydrazine hydrate, the product still maintains its original size and morphology ( image 3 c, d), these structural characteristics are conducive to the composite cathode material to show better lithium storage performance.

[0038] Figure 4 It is the charge and discharge curve of the S/rGO composite material synthesized in this example and pure sulfur. It can be seen from the discharge curve that both S/rGO composite materials and pure sulfur exhibit a typical double plateau curve, which corresponds to the conversion of sulfur to lithium polysulfide and finally to lithium sulfide; compared with pure sulfur, S/rGO composite material is the first The two platforms contribute more capacity.

[0039] Figure 5 It is the charge-discharge cycle performance diagram of the S/rGO composite material synthesized in this example and pure sulfur. It can be seen from the figure that at a charge-discharge current density of 0.1C, the first-cycle discharge specific capacity of the S/rGO composite is 711mAh g -1 , Higher than the discharge specific capacity of pure sulfur (573mAh g -1 ); After 300 charge-discharge cycles, the specific discharge capacity of S/rGO composite is still as high as 421mAh g -1 , Higher than the discharge specific capacity of pure sulfur (173mAh g -1 ), showing superior cycle performance and higher specific capacity.

[0040] Image 6 It is the charge-discharge rate performance graph of the S/rGO composite material and pure sulfur synthesized in this example. It can be seen from the figure that when the current density is 0.1, 0.2, 0.5 and 1C, the average specific discharge capacity of the product is about 680, 560, 420 and 320mAhg, respectively -1; When the current density returns from 1C to 0.1C, the average specific discharge capacity of the product returns to 560mAh g -1 , Are higher than the specific capacity of pure sulfur, which shows that the S/rGO composite material has good rate performance and is expected to be commercialized on the positive electrode of lithium-sulfur power battery.

Example Embodiment

[0041] Example 2

[0042] (1) Preparation of three-dimensional graphene oxide aerogel sulfur-carrying (S/GO) composite: 25mg graphene oxide and 50mg sublimed sulfur were dispersed in 5mL distilled water, and 0.5mL 10mgmL was added at room temperature (25℃) -1 Chitosan (molecular weight: 150,000)/acetic acid aqueous solution (volume ratio of acetic acid to water is 5:95), stir until a hydrogel is formed, and then stand at room temperature for 6 hours, freeze-dry, to obtain three-dimensional graphite oxide Sulfur-loaded olefin aerogel (S/GO) composite material.

[0043] (2) Preparation of three-dimensional graphene aerogel sulfur-supported (S/rGO) composite material: 80 mg of the product obtained in step (1) was dispersed in 5 mL of distilled water, and 0.3 mL of ammonia (30 wt%) and 0.2mL hydrazine hydrate (40wt%) was reacted for 2 hours, filtered with suction and washed with distilled water until the filtrate was neutral, and the collected solids were freeze-dried to obtain the three-dimensional graphene aerogel sulfur (S/rGO) composite material.

[0044] The prepared three-dimensional graphene aerogel sulfur-supported composite material was subjected to related tests and characterizations similar to those in Example 1, and the conclusions obtained were similar to those in Example 1.

Example Embodiment

[0045] Example 3

[0046] (1) Preparation of three-dimensional graphene oxide aerogel sulfur-carrying (S/GO) composite material: Disperse 50 mg of graphene oxide and 100 mg of sublimed sulfur in 5 mL of distilled water, and add 0.5 mL of 10 mg mL at room temperature (25°C) -1 Chitosan (molecular weight: 150,000)/acetic acid aqueous solution (volume ratio of acetic acid to water is 5:95), stir until a hydrogel is formed, and then stand at room temperature for 6 hours, freeze-dry, to obtain three-dimensional graphite oxide Sulfur-loaded olefin aerogel (S/GO) composite material.

[0047] (2) Preparation of three-dimensional graphene aerogel sulfur-supported (S/rGO) composite material: 155 mg of the product obtained in step (1) was dispersed in 10 mL of distilled water, and 0.3 mL of ammonia (15 wt%) and 0.2mL hydrazine hydrate (50wt%) was reacted for 1.2 hours, filtered with suction and washed with distilled water until the filtrate was neutral, and the collected solids were freeze-dried to obtain the three-dimensional graphene aerogel sulfur-carrying (S/rGO) composite material.

[0048] The prepared three-dimensional graphene aerogel sulfur-supported composite material was subjected to related tests and characterizations similar to those in Example 1, and the conclusion was similar to that in Example 1.

PUM

Property	Measurement	Unit
Discharge specific capacity	711.0	m

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Classification and recommendation of technical efficacy words

Easy to scale production

Three-dimensional graphite aerogel sulfur-carrying composite material as well as preparation method and application thereof

AI-Extracted Technical Summary

Problems solved by technology

Abstract

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Examples

Example Embodiment

Example Embodiment

Example Embodiment

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Description & Claims & Application Information

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