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Carbon-sulfur composite material used for positive pole of lithium-sulfur battery and preparation method of material

A composite material, lithium-sulfur battery technology, applied in the direction of battery electrodes, circuits, electrical components, etc., can solve the problems of battery cycle life to be improved, limited active material utilization, active material loss, etc., to achieve large specific capacity, inhibit dissolution , Improve the effect of wettability

Active Publication Date: 2013-03-13
NANKAI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] At present, there are three major obstacles to the development of lithium-sulfur batteries: 1) The cathode material sulfur is a typical electronic and ion insulator at room temperature, and its electronic conductivity is only 5×10 -30 S cm -1 , which limits the utilization of active materials; 2) The intermediate product lithium polysulfides produced during charge and discharge have a high solubility in organic electrolytes, and these polysulfide ions migrate to the lithium anode through the separator and react with lithium to form Li 2 S 2 or Li 2 S, causing the loss of active material, that is, "shuttle loss"; 3) During the cycle, the sulfur electrode undergoes a large volume change, which accelerates the capacity decline
In response to the above problems, various solutions have been proposed, including designing new electrolytes, compounding sulfur with carbon, compounding sulfur with polymers, organic sulfides, etc. (A.Manthiram, Y.Fu, Y.-S.Su ,Challenges and Prospects of Lithium-Sulfur Batteries.Acc.Chem.Res.,2012,DOI:10.1021 / ar300179v), but the utilization rate of the electrode active material and the cycle life of the battery need to be improved

Method used

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  • Carbon-sulfur composite material used for positive pole of lithium-sulfur battery and preparation method of material
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  • Carbon-sulfur composite material used for positive pole of lithium-sulfur battery and preparation method of material

Examples

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Effect test

Embodiment 1

[0027] A method for preparing a carbon-sulfur composite material for a positive electrode of a lithium-sulfur battery, the steps are as follows:

[0028] (1) Preparation of porous hollow carbon spheres

[0029] 1) Dissolve 0.5g of 2123# thermoplastic phenolic resin in 20mL of absolute ethanol to obtain a mixed solution, stir in a water bath at 50°C, add tetraethyl orthosilicate, the mass ratio of tetraethyl orthosilicate to the mixed solution is 1:12 , continue to stir for 15 minutes to form a light yellow transparent mixture;

[0030] 2) Quickly pour 50mL of ammonia-water-ethanol mixed solution with a volume ratio of 1:4 into the above-mentioned transparent mixed solution, stir vigorously, react at 50°C for 3h, slowly evaporate to dryness, and dry at 60°C for 12h to obtain a solid product ;

[0031]3) Grind the above solid product evenly, heat it to 850°C in an argon atmosphere at a heating rate of 5°C / min, react for 2 hours, and then pour it into a hydrofluoric acid soluti...

Embodiment 2

[0043] A method for preparing a carbon-sulfur composite material for a positive electrode of a lithium-sulfur battery, the steps are as follows:

[0044] The preparation of porous hollow carbon spheres is the same as in Example 1.

[0045] The preparation of the carbon-sulfur composite material is basically the same as in Example 1, but the mass ratio of sublimated sulfur to porous hollow carbon spheres is 2:1.

[0046] The assembly and testing of the positive electrode sheet, the negative electrode sheet and the button cell are the same as in Example 1.

[0047] The X-ray diffraction pattern shows that a small amount of sulfur is not dispersed in the pores of the porous hollow carbon spheres, and the diffraction peaks of elemental sulfur have appeared, such as Figure 4 shown. Figure 8 It is the first constant current charge and discharge curve of the battery. The two discharge platforms are located at about 2.05 and 2.30V respectively, and the discharge specific capacity ...

Embodiment 3

[0049] A method for preparing a carbon-sulfur composite material for a positive electrode of a lithium-sulfur battery, the steps are as follows:

[0050] The preparation of porous hollow carbon spheres is the same as in Example 1.

[0051] The preparation of the carbon-sulfur composite material is basically the same as in Example 1, but the mass ratio of sublimated sulfur to porous hollow carbon spheres is changed to 3:1.

[0052] The assembly and testing of the positive electrode sheet, the negative electrode sheet and the button cell are the same as in Example 1.

[0053] The X-ray diffraction pattern shows that part of the sulfur exists outside the pores of the porous hollow carbon spheres, the carbon wrapping peak is not obvious, and the diffraction peak of the elemental sulfur is stronger, as shown in Figure 4 shown. Figure 9 It is the first constant current charge and discharge curve of the battery. The two discharge platforms are respectively located at about 2.05 a...

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Abstract

The invention relates to a carbon-sulfur composite material used for a positive pole of a lithium-sulfur battery. The carbon-sulfur composite material is characterized in that elemental sulfur is filled in a multi-hole hollow carbon ball which is synthesized through a simple template method, and the elemental sulfur is injected into the multi-hole hollow carbon ball by adopting a fusion diffused method; the carbon-sulfur composite material is used for preparing a positive pole material of a high-performance lithium-sulfur battery cell, the positive pole is composed of the carbon-sulfur composite material, a binding agent and an electric conduction agent, and polytetrafluoroethylene or polyvinylidene fluoride is used as the binding agent; and the electric conduction agent is a mixture of one or more than two of carbon nanometer fibre, electric conduction graphite, acetylene black and Super p in any proportion. The carbon-sulfur composite material provided by the invention has the advantages that compared with the reportorial lithium-sulfur secondary battery, the preparation method of the anode material is simple, the large specific capacity is 1450 Ahg-1, the coulomb efficiency is high and is greater than 99.0%, the cycle performance is good, the initial capacity is kept 93.6% after circulating for 50 weeks and the like, and the carbon-sulfur composite material is expected to be applied to the next generation large-scale stored energy batteries.

Description

technical field [0001] The invention relates to the preparation of lithium-sulfur batteries in the field of electrochemical batteries, in particular to a carbon-sulfur composite material used for the positive electrode of lithium-sulfur batteries and a preparation method thereof. Background technique [0002] With the decline of oil production and the intensification of global environmental pollution, renewable energy sources such as wind energy, solar energy, and biomass energy have attracted widespread attention. The conversion and storage of electrochemical energy is very important for the utilization of renewable energy, and many electric devices also require advanced electrochemical energy storage technology to improve energy density and power density. There is an urgent need for chemical power sources with high safety, low cost, high capacity, and long life to replace traditional energy sources. In a variety of battery systems, lithium-sulfur batteries have a high the...

Claims

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Application Information

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IPC IPC(8): H01M4/38
CPCY02E60/12Y02E60/10
Inventor 陈军张凯赵庆陶占良程方益梁静李海霞
Owner NANKAI UNIV
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