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Poly-sulfur positive electrode material and lithium-sulfur secondary battery prepared from same

A lithium-sulfur secondary battery and cathode material technology, applied in lithium batteries, battery electrodes, non-aqueous electrolyte batteries, etc., can solve the problems of low reversible capacity and low Coulombic efficiency of batteries, achieve improved polysulfide dissolution shuttle, and simple process , the effect of convenient operation

Active Publication Date: 2019-04-05
BEIHANG UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The "polysulfide shuttle" effect is the reason for the low reversible capacity and low coulombic efficiency of the current batteries, and the root cause is the dissolution of polysulfide. Therefore, in addition to suppressing the work of "polysulfide shuttle" by improving the diaphragm, a lot of work has been done. Focus on inhibiting polysulfide dissolution

Method used

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  • Poly-sulfur positive electrode material and lithium-sulfur secondary battery prepared from same
  • Poly-sulfur positive electrode material and lithium-sulfur secondary battery prepared from same
  • Poly-sulfur positive electrode material and lithium-sulfur secondary battery prepared from same

Examples

Experimental program
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Effect test

Embodiment 1

[0034] A polymeric sulfur cathode material based on the polymerization of thiuram and sulfur, which is prepared by the following steps:

[0035] Weigh 5g of sublimed sulfur powder (99.5%, see Figure 4 The powder on the far right) is put into a two-necked flask, plug the bottle mouth with a stopper, put a small magnet, and immerse the flask in an oil bath at about 130°C for heating. After the sulfur powder is completely melted, add 5g of dimethylthiuram tetrasulfide, then adjust the temperature to 175°C and keep it warm for 4 hours. During this period, keep magnetic stirring to make the reaction even.

[0036] After natural cooling, the obtained polysulfide was taken out, firstly ground for ten minutes with an agate mortar, then put into a ball mill for grinding at 300 r / min for 15 minutes, and finally vacuum-dried at 60°C for 4 hours.

[0037] The XRD diffraction pattern of the material is shown in Figure 7 , whose XRD peak is the same as that of elemental sulfur. Product...

Embodiment 2

[0041] A polymeric sulfur cathode material based on the polymerization of thiuram and sulfur, the preparation method of which is basically the same as in Example 1, except that the conductive agent Super P in the lithium-sulfur battery is changed to reduced graphene (RGO).

[0042] The method for making a lithium-sulfur secondary battery with the obtained polymerized sulfur cathode material is as follows:

[0043] Take 24mg of the polysulfide positive electrode material prepared in Example 1, grind and mix with 3mg reduced graphene and 3mg polyvinylidene fluoride (PVDF) to make a homogeneous slurry, and then coat the homogeneous slurry on Aluminum foil, and then vacuum-dry at 60 degrees, and then take it out and assemble the battery under the protection of argon in the glove box. The negative electrode of the battery is a lithium sheet, the separator is a PE film, and the electrolyte is 1.0M LITFSI dissolved in a lithium-sulfur electrolyte with a volume ratio of DME:DOL=1:1 to...

Embodiment 3

[0045] A polymeric sulfur cathode material based on the polymerization of thiuram and sulfur, the preparation method of which is basically the same as in Example 1, except that the mass ratio of dimethylthiuram tetrasulfide and sulfur in Example 1 is changed to 2:1.

[0046] The resulting powder becomes darker after the polymerization is complete, see Figure 4 Powder on the far left. The electrochemical performance of the obtained polymeric sulfur electrode was characterized, and the initial capacity was only 270mAh g at a current density of 0.2C -1(Based on the total mass of the active material), this is due to the large particles of the material itself in the first cycle, and its poor conductivity. As the charge and discharge progress, ions can slowly enter the interior of the positive electrode material for activation, so the subsequent capacity increases to 540mAh g -1 , the capacity remains at 320mAh g after 200 cycles -1 .

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Abstract

The invention provides a poly-sulfur positive electrode material. Steps for preparing the poly-sulfur positive electrode material include 1), carrying out polymerization reaction on simple sulfur substances in molten states and thiuram organic polymerizing agents; 2), grinding and smashing reaction products after the polymerization reaction is completely carried out. The thiuram organic polymerizing agents are a type or a plurality of types of thiuram monosulfide, thiuram disulfide and thiuram polysulfide. The invention further provides a lithium-sulfur secondary battery prepared from the poly-sulfur positive electrode material. The poly-sulfur positive electrode material and the lithium-sulfur secondary battery have the advantages that the material preparation requirements can be met by simple heating equipment, processes for producing the poly-sulfur positive electrode material are convenient to operate and are simple, thiuram is extremely low in cost, and accordingly the poly-sulfurpositive electrode material is low in synthesis cost; macromolecular polymerized sulfide can be polymerized, the related problems such as poly-sulfur dissolution and shuttling of lithium-sulfur batteries can be solved when poly-sulfur is used as a positive electrode of the lithium-sulfur secondary battery, and the lithium-sulfur secondary battery is stable in cycle performance and long in cycle life.

Description

technical field [0001] The invention belongs to the field of energy materials, and in particular relates to a positive electrode material for a battery and a lithium-sulfur battery prepared therefrom. Background technique [0002] Since the development of the first rechargeable battery-lead-acid battery in 1859, the electrochemical energy storage system has been developed for more than 150 years, and its energy density has increased from ~30Wh / kg (lead-acid battery) to the current 150Wh / kg ( commercial lithium-ion batteries). Among the many candidates for high-energy-density batteries, lithium-sulfur batteries are one of the most promising secondary batteries due to their high energy density of 2600Wh / kg. [0003] In addition, the positive electrode of lithium-sulfur battery is sulfur element, which has the advantages of abundant raw materials, low price and environmental friendliness. However, there are still many challenges in the development process of lithium-sulfur ba...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08G75/14H01M4/60H01M10/052
CPCC08G75/14H01M4/602H01M10/052Y02E60/10
Inventor 杨树斌李彬朱孟琪
Owner BEIHANG UNIV
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