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Method for preparing lithium-sulfur battery positive electrode material from composite carbon nanofibers

A nanofiber and cathode material technology, which is applied in the field of composite carbon nanofibers to prepare lithium-sulfur battery cathode materials, can solve the problems of polysulfide leakage, lithium-sulfur battery safety problems, low utilization rate of active materials, etc., and achieves fast electron and ion The effect of transmission, improving cycle stability, and suppressing the shuttle effect

Pending Publication Date: 2021-10-26
SHANGHAI UNIVERSITY OF ELECTRIC POWER
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] 1) Sulfur and its various discharge products (Li2S x , x=1-8) have poor ionic conductivity and electronic conductivity, resulting in high internal resistance of the battery and low utilization of active materials
[0004] 2) During the discharge process, intermediate and high-order polysulfides (Li 2 S x , 62 S x , 22 S 2 and Li 2 S, not only causes irreversible sulfur loss, but also causes corrosion on the Li surface, resulting in low Coulombic efficiency and poor cycle stability;
[0005] 3) Sulfur and final product Li 2 The density of S is different. When sulfur is lithiated, the volume expands by about 79%, which easily leads to Li 2 Pulverization of S, causing safety problems in lithium-sulfur batteries
However, the physical confinement of carbon nanomaterials still leads to the leakage of polysulfides, which leads to a decrease in electrode conductivity and sulfur utilization, accompanied by a higher capacity fade rate.

Method used

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  • Method for preparing lithium-sulfur battery positive electrode material from composite carbon nanofibers
  • Method for preparing lithium-sulfur battery positive electrode material from composite carbon nanofibers
  • Method for preparing lithium-sulfur battery positive electrode material from composite carbon nanofibers

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Embodiment 1

[0029] In this example, the preparation method of the composite carbon nanofiber as the host material of the positive electrode of the lithium-sulfur battery is described in detail, which specifically includes the following steps:

[0030] Step S1: Take 340mg (NH 4 ) 2 MoO 4 , 400mg PS and 500mg PAN were dissolved in 40ml of DMF solution to prepare a precursor solution.

[0031] Step S2: Electrospinning the precursor solution on the aluminum foil collector. The distance between the syringe and the aluminum foil was fixed at 18 cm, and the flow rate was 1 ml h -1 . The spinning product obtained is at N 2 Raise the temperature to 850°C under the atmosphere and keep it for 2h, the heating rate is 2°C / min, to obtain Mo 2 C NPs-CNFs cathode host material.

[0032] Step S3: 3.72g sulfur and 1.24g Mo 2 C NPs-CNFs were ground and mixed, then added 3ml of carbon disulfide and continued to grind for 50 minutes. After they were fully mixed, they were put into the reaction kettle ...

Embodiment 2

[0043] In this embodiment, the preparation method of composite carbon nanofibers in different proportions from Example 1 as the positive electrode host material for lithium-sulfur batteries is described in detail, and specifically includes the following steps:

[0044] Step S1: Take 360mg (NH 4 ) 2 MoO 4 , 420mg PS and 510mg PAN were dissolved in 50ml of DMF solution to prepare a precursor solution.

[0045] Step S2: Electrospinning the precursor solution on the aluminum foil collector. The distance between the syringe and the aluminum foil was fixed at 18 cm, and the flow rate was 1.5 ml h -1 . The spinning product obtained is at N 2 Raise the temperature to 900°C under the atmosphere and keep it for 2h, the heating rate is 5°C / min, to obtain Mo 2 C NPs-CNFs electrodes.

[0046] Step S3: combine sulfur and Mo 2 C NPs-CNFs were ground and mixed, and then carbon disulfide (sulfur, Mo 2 C. The ratio of NPs-CNFs to carbon disulfide is: 2.34g; 0.78g; 3ml) continue to grin...

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Abstract

The invention relates to a method for preparing a lithium-sulfur battery positive electrode material from composite carbon nanofibers, which comprises the following steps: (1) dissolving (NH4)2MoO4, polystyrene and PAN in a DMF solution to form a precursor solution; (2) performing electrostatic spinning on the precursor solution, and drying and sintering an obtained spinning product to obtain a Mo2C NPs-CNFs positive electrode host material; and (3) grinding and mixing sulfur and the Mo2C NPs-CNFs positive electrode host material, then adding carbon disulfide, continuously grinding, putting the obtained mixture into a reaction kettle, and heating and reacting to obtain the target product Mo2C NPs-CNFs / S positive electrode material. Compared with the prior art, the shuttle effect of polysulfide can be effectively inhibited, the problem of volume expansion of the positive electrode in the charging and discharging process of the battery can be relieved, and the cycling stability of the battery is improved.

Description

technical field [0001] The invention belongs to the technical field of electrode material preparation, and relates to a method for preparing lithium-sulfur battery cathode materials with composite carbon nanofibers. Background technique [0002] In a lithium-sulfur battery with elemental sulfur as the positive electrode and metal lithium as the negative electrode, during the discharge process, the lithium metal negative electrode is oxidized to form lithium ions and electrons, which reach the sulfur positive electrode through the electrolyte and external circuit respectively. On the positive electrode side, sulfur reacts with lithium ions and electrons and is reduced to lithium sulfide. It has a high theoretical specific capacity (1672mA h g -1 ) and theoretical energy density (2600Wh kg -1 ), in addition, elemental sulfur has the characteristics of high reserves, low price, and environmental friendliness. However, the low electrochemical utilization rate and fast capacit...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/38H01M4/583H01M4/62H01M10/052C01B32/15
CPCH01M4/62H01M4/583H01M4/625H01M4/38H01M10/052C01B32/15Y02E60/10
Inventor 闵宇霖张海燕张宇鹏耿远顾榕赵奕韡徐群杰
Owner SHANGHAI UNIVERSITY OF ELECTRIC POWER