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Nanometer sulfur-based positive electrode composite material for lithium sulfur batteries, and preparation method thereof

A composite material, lithium-sulfur battery technology, applied in the field of electrochemical energy and nano-materials, can solve the problems of poor electronic conductivity and ion conductivity, a large amount of organic solvents and surfactants, and the reduction of sulfur utilization rate of active substances, etc., to improve The effect of conductivity, improvement of electrochemical performance, and fast chemical reaction rate

Active Publication Date: 2015-09-09
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] However, lithium-sulfur batteries also have some defects: first, the electronic conductivity and ionic conductivity of elemental sulfur and its discharge product lithium sulfide are very poor, and it is generally necessary to add other conductive materials to improve the conductivity of the electrode; second, The intermediate product lithium polysulfide generated by the reaction of sulfur in the process of charge and discharge is easier to dissolve in the electrolyte and shuttle back and forth between the positive and negative electrodes, resulting in a decrease in the utilization rate of sulfur in the active material and corrosion of the lithium negative electrode, making the battery cycle stable. Third, due to the difference in density between sulfur and the discharge product lithium sulfide, the volume of the electrode changes by 80% during the discharge process, and the huge volume change in the repeated charge and discharge process destroys the structure of the positive electrode.
The chemical vapor deposition method needs to be carried out under the protection of high temperature and inert gas, the preparation conditions are harsh, the energy consumption is large, and the cost is high, so it is not suitable for industrial production (patent CN 1453205 A)
Ultrasonic solvent conversion method consumes a lot of energy, has low yield, and is difficult for large-scale production (patent CN 1636865 A)
Although the water-oil two-phase microemulsion method can obtain nano-sulfur materials with a regular spherical structure, this method requires a large amount of organic solvents and surfactants, and the subsequent cleaning process is cumbersome (Powder Technology, 2006, 162, 83- 86)

Method used

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  • Nanometer sulfur-based positive electrode composite material for lithium sulfur batteries, and preparation method thereof
  • Nanometer sulfur-based positive electrode composite material for lithium sulfur batteries, and preparation method thereof
  • Nanometer sulfur-based positive electrode composite material for lithium sulfur batteries, and preparation method thereof

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Effect test

Embodiment 1

[0049] At 25°C, take 3.4901g of sodium thiosulfate pentahydrate and completely dissolve it in 250mL of deionized water, add 2 drops of 3wt% Triton X-100, and after ultrasonic dispersion for 10min, transfer the obtained clear reaction solution into a constant temperature water bath at 70°C 20mL of concentrated hydrochloric acid was dissolved in 1.5mL min under continuous stirring -1 Add the above reaction solution at a high speed until the solution is acidic (pH ≤ 2), continue to stir and keep warm for 2 hours, then transfer the obtained elemental sulfur solution into an ice-bath reactor at 0-5°C, and add 0.1 mL of pyrrole, after continuous stirring for 25 minutes, 0.4132 g of ammonium persulfate was added at one time to fully react for 8 hours, and the obtained core-shell sulfur-polypyrrole nanoparticle solution was ready for use. Graphene oxide prepared by the Hummers method was diluted to 0.65 mg mL with deionized water -1 And ultrasonically dispersed for 2 hours, under the...

Embodiment 2

[0052] At 25°C, take 3.2873g of sodium thiosulfate pentahydrate and completely dissolve it in 200mL of deionized water, add 2 drops of 2wt% PVP, and ultrasonically disperse for 10 minutes, then transfer the obtained clear reaction solution into a constant temperature water bath at 70°C, and continuously With stirring, 20 mL of concentrated hydrochloric acid was dissolved in 1.5 mL min -1 Add the above reaction solution at a high speed until the solution is acidic (pH ≤ 2), continue to stir and keep warm for 2 hours, then transfer the obtained elemental sulfur solution into an ice bath reactor at 0-5°C, and add 0.2 After stirring continuously for 20 min, add 0.5317 g of potassium persulfate to fully react for 7 h, and the obtained core-shell sulfur-polyaniline nanoparticle solution is ready for use. Graphene oxide prepared by the Hummers method was diluted to 1.2 mg mL with deionized water -1 And ultrasonically dispersed for 2 hours, under the condition of constant stirring, t...

Embodiment 3

[0055] At 25°C, take 3.4901g of sodium thiosulfate pentahydrate and completely dissolve it in 300mL of deionized water, add 2 drops of 3wt% Triton X-100, ultrasonically disperse it for 10min, then transfer the obtained clear reaction solution into a constant temperature water bath at 70°C In 1 mL min of 15 mL of concentrated hydrochloric acid with continuous stirring -1 Add the above reaction solution at a high speed until the solution is acidic (pH ≤ 2), continue to stir and keep warm for 2 hours, then transfer the obtained elemental sulfur solution into an ice-bath reactor at 0-5°C, and add 0.1 mL of pyrrole, after continuous stirring for 15 minutes, 0.3756 g of ammonium persulfate was added at one time to fully react for 6 hours, and the obtained core-shell sulfur-polypyrrole nanoparticle solution was ready for use. Graphene oxide prepared by the Hummers method was diluted to 1.85 mg mL with deionized water -1 And ultrasonically dispersed for 2 hours, under the condition o...

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Abstract

The invention discloses a nanometer sulfur-based positive electrode composite material for lithium sulfur batteries, and a preparation method thereof. The positive composite material is prepared through compounding a core-shell structure with reduced graphene oxide, the core-shell structure is formed by nanometer elemental sulfur and a conductive polymer nanoparticle, and the sulfur-conductive polymer nanoparticle core-shell structure is uniformly inlaid between graphene sheets to form a sandwiched three-dimensional conductive network. The preparation method of the positive electrode composite material comprises the following steps: forming the core-shell structure through in situ polymerization of the conductive polymer nanoparticle on the surface of the nanometer elemental sulfur core prepared through a low temperature liquid phase technology, and coating the surface of the core-shell structure with the reduced graphene oxide to obtain the positive electrode composite material for lithium sulfur batteries. The positive electrode composite material has the advantages of simple preparation process, low cost, small energy consumption, controllable sulfur content, strong repeatability and easy large-scale production. The positive electrode composite material can improve the discharge specific capacity of a battery material and the active substance utilization rate as a lithium sulfur battery positive electrode material in order to greatly improve the cycle performances of the battery.

Description

technical field [0001] The present invention relates to a cathode composite material for a lithium-sulfur battery based on nano-sulfur and a preparation method thereof, in particular to a cathode composite material with a core-shell structure composed of graphene-coated elemental sulfur and conductive polymer nanoparticles and a preparation method thereof. The invention belongs to the field of electrochemical energy and nanometer material technology. Background technique [0002] With the continuous reduction of petrochemical energy, the development and utilization of new energy is imminent. Energy storage devices with high energy density and long cycle life are the key to the efficient use of new energy. Among the currently developed energy storage systems, lithium-sulfur batteries have a high theoretical energy density (2600Wh kg -1 ), and elemental sulfur is rich in resources, low in price and environmentally friendly, with great development potential and application pro...

Claims

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Application Information

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IPC IPC(8): H01M4/38H01M4/62B82Y40/00B82Y30/00
CPCB82Y30/00B82Y40/00H01M4/38H01M4/624H01M4/625H01M4/628H01M10/0525Y02E60/10
Inventor 周向阳杨娟陈锋唐晶晶柏涛廖群超
Owner CENT SOUTH UNIV
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