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Melamine-based externally-coated porous carbon-sulfur composite material as well as preparation method and application thereof

A melamine and composite material technology, applied in the direction of positive electrode, active material electrode, structural parts, etc., can solve the problem of uneven dispersion of active material sulfur, reduce shedding loss, stabilize porous morphology, and improve electrochemical cycle performance. Effect

Pending Publication Date: 2020-04-10
GUILIN UNIV OF ELECTRONIC TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0007] 1. The problem of uneven dispersion of the active substance sulfur in the positive electrode material;

Method used

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  • Melamine-based externally-coated porous carbon-sulfur composite material as well as preparation method and application thereof
  • Melamine-based externally-coated porous carbon-sulfur composite material as well as preparation method and application thereof
  • Melamine-based externally-coated porous carbon-sulfur composite material as well as preparation method and application thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0032] A method for preparing a melamine-based outer coating porous carbon-sulfur composite material, comprising the following steps:

[0033] Step 1) Preparation of melamine-based porous carbon by hydrothermal method, 6.30 g of melamine was uniformly dispersed in 300 mL of distilled water to form a suspension, and 3.5 mL of phosphoric acid was added to the suspension at 60 °C, and the reaction was stirred 5–7 h, washed and dried to obtain a melamine-based porous carbon precursor. The obtained melamine-based porous carbon precursor was kept at 500 °C for 1 h under a nitrogen atmosphere, and continued to heat up to 800 °C for another 2 h to obtain a melamine-based porous carbon;

[0034] Step 2) Preparation of melamine-based coated porous carbon by low-temperature liquid phase polymerization. Take 0.4 g of the melamine-based porous carbon obtained in step 1) and uniformly disperse it in 200 mL of distilled water to form a suspension. Add 0.8 g cetyltrimethylammonium chloride, 4 ...

Embodiment 2

[0049] A preparation method of melamine-based coated porous carbon (the mass ratio of melamine-based porous carbon to pyrrole is 1:5), the steps not specified are the same as in Example 1, except that: step 2) adds The amount of pyrrole was 2 mL.

[0050] Figure 7 The lithium-sulfur battery prepared for Comparative Example 2 has a current density of 167.5 mA / cm 2 Cyclic performance image at time. The first discharge specific capacity of the lithium-sulfur battery of this comparative example is 1190 mAh / g, and after 200 cycles, the specific capacity decays to 360 mAh / g, and the cycle performance is greater than that of Example 1 when the capacity of the first cycle is close to that of Example 1. Due to the lack of sufficient outer coating to bind polysulfides, the dissolution and diffusion of polysulfides will produce a "shuttle effect" in the electrolyte, resulting in a decrease in cycle performance.

Embodiment 3

[0052] A preparation method of melamine-based coated porous carbon (the mass ratio of melamine-based porous carbon to pyrrole is 1:20), the steps not particularly specified are the same as in Example 1, the difference is that in step 2) add The amount of pyrrole was 8 mL.

[0053] Figure 8 The lithium-sulfur battery prepared for Comparative Example 3 had a current density of 167.5 mA / cm 2 Cyclic performance image at time. The first discharge specific capacity of the lithium-sulfur battery of this comparative example is 687 mAh / g, after 200 cycles, the specific capacity decays to 489 mAh / g, and the cycle performance is slightly improved, and its first cycle capacity is compared with that of Example 1 There is a large drop, due to the complete coating, the reaction area between the active material sulfur and the electrolyte is reduced, and the sulfur loading is also reduced to less than 50%.

[0054] The experimental results show that coating the porous carbon surface is an ...

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Abstract

The invention discloses a melamine-based externally-coated porous carbon-sulfur composite material as well as a preparation method and application thereof. The melamine-based externally-coated porouscarbon-sulfur composite material takes melamine, pyrrole and sulfur as raw materials, and is obtained through a hydrothermal method, a low-temperature liquid-phase polymerization method and a meltingmethod, wherein the sulfur content is 65-75%. The preparation method of the melamine-based externally-coated porous carbon-sulfur composite material comprises the following steps of synthesizing melamine phosphate through the hydrothermal method to prepare melamine-based porous carbon, then preparing the melamine-based externally-coated porous carbon through the low-temperature liquid-phase polymerization method, and finally preparing the activated melamine-based externally-coated porous carbon-sulfur composite material through the melting method. When the material is used as the positive electrode of a lithium-sulfur battery, the first specific discharge capacity is 1000-1100 mAh / g, and after 100 cycles, the specific capacity is attenuated to 450-550 mAh / g. The invention has the followingadvantages that 1, the high specific capacity and electrochemical cycle performance is realized; 2, the morphology of the carbon carrier is stable, and the outer coating structure effectively inhibits the shuttle effect and reduces the shedding loss of the active substance sulfur; and 3, the active substance sulfur is uniformly distributed, so that the sulfur loading capacity is increased.

Description

technical field [0001] The invention belongs to the technical field of batteries, in particular to a melamine-based outer-coated porous carbon-sulfur composite material and a preparation method and application thereof. Background technique [0002] With the continuous development of society, human demand for energy is also increasing. However, with the continuous exploitation of fossil fuel resources for nearly 200 years, the fossil fuel resources have tended to be exhausted, and the environmental pollution caused by the burning of fossil fuels has become a major challenge for human survival. Therefore, energy issues and environmental security issues have become global concerns and urgently need to be resolved. The development of secondary batteries with high energy, high density, high safety, green environmental protection and low cost is of great significance in the field of new energy. Lithium-sulfur battery is a secondary battery with high energy density. It uses eleme...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/583H01M4/60H01M10/0525
CPCH01M4/366H01M4/38H01M4/583H01M4/602H01M10/0525H01M2004/028Y02E60/10
Inventor 孙立贤管彦洵徐芬程日光
Owner GUILIN UNIV OF ELECTRONIC TECH
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