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Lithium-sulfur battery gel-state positive electrode and preparation method thereof

A lithium-sulfur battery, gel state technology, applied in the direction of gel electrodes, electrode manufacturing, battery electrodes, etc., can solve the problems of unfavorable battery volume or mass specific energy, limited improvement of battery performance, difficulty in reducing the amount of electrolyte, etc. , to achieve the effects of good operability, performance improvement and good practicability

Inactive Publication Date: 2021-03-12
XI'AN UNIVERSITY OF ARCHITECTURE AND TECHNOLOGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The combination of sulfur and conductive materials can improve the conductivity of the electrode and confine lithium polysulfides to a certain extent, but it cannot fundamentally solve the problem of volume change in the process of lithium polysulfide dissolution / shuttle and intercalation and delithiation, and the conductive phase as an inactive component will also lead to a decrease in the actual specific capacity of the electrode
The use of flexible polymer materials in the electrode can better adapt to the volume change before and after sulfur lithiation, but the conductivity of most polymers deviates
The use of organic solvents with low dielectric constant and weak solvent capability can inhibit the dissolution of lithium polysulfide, but the ionic conductance of the electrolyte is affected, and the amount of electrolyte is difficult to reduce
Setting a barrier layer between the positive and negative electrodes can physically prevent the diffusion of lithium polysulfide, but as an inactive component, these barrier layers are not conducive to the increase of the volume or mass specific energy of the battery
[0004] To sum up, the existing modification and optimization measures for lithium-sulfur batteries have certain limitations, and cannot solve the various problems of lithium-sulfur batteries from an overall perspective, so the improvement of battery performance is limited.

Method used

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  • Lithium-sulfur battery gel-state positive electrode and preparation method thereof
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  • Lithium-sulfur battery gel-state positive electrode and preparation method thereof

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preparation example Construction

[0049] A preparation method of a lithium-sulfur battery gel state positive electrode of the present invention comprises the following steps:

[0050] S1. Mix elemental sulfur and lithium sulfide in a molar ratio of 7:1 to 3:1 and add them into a high dielectric constant solvent, fully dissolve and react to prepare an electrolyte solution containing lithium polysulfide;

[0051] S2. After mixing the conductive polymer and the easy-gelling polymer in a solvent at a mass ratio of 1:9 to 5:5, coat it on a support, and dry it at 25 to 85 degrees for 12 to 48 hours to obtain a polymer skeleton;

[0052] S3. Soak the polymer skeleton in the electrolyte solution for 0.5-24 hours, or inject the electrolyte solution into the polymer skeleton, form a gel layer after fully swelling, and obtain a gel state positive electrode.

Embodiment 1

[0055] After mixing elemental sulfur and lithium sulfide in DMA with a molar ratio of 5:1, add appropriate amount of LiTFSI and LiNO 3 , made containing Li 2 S 6 electrolyte, Li 2 S 6 The concentration is 80% of its saturation solubility in DMA.

[0056] Stir PEDOT / PSS, P(AM-co-AA), and PEO in NMP / deionized water mixed solvent, coat on carbon fiber cloth, and dry to obtain a polymer with a thickness of 80um (deducting the thickness of carbon fiber cloth) skeleton. Li will be prepared 2 S 6 The electrolyte solution is injected into the polymer framework, and the gel-state positive electrode is obtained after sufficient swelling.

[0057] The above-mentioned condensed positive electrode, porous diaphragm, and lithium sheet are sequentially stacked, and sealed in a button case to assemble a lithium-sulfur battery.

Embodiment 2

[0059] After mixing elemental sulfur and lithium sulfide in DMSO at a molar ratio of 7:1, and then adding an appropriate amount of LiFSI, a Li-containing 2 S 8 electrolyte, Li 2 S 8 The concentration is 95% of its saturation solubility in DMSO.

[0060] Stir PPy and PVDF-HFP in DMF / deionized water mixed solvent, coat on the surface of carbon paper, and dry to obtain a polymer skeleton with a thickness of 200um (deducting the thickness of carbon paper). Soak the polymer backbone in Li 2 S 8 In the electrolyte, a gel-state positive electrode is obtained after being fully swollen.

[0061] The above-mentioned condensed positive electrode, porous diaphragm, and lithium sheet are sequentially stacked, and sealed in a button case to assemble a lithium-sulfur battery.

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Abstract

The invention discloses a lithium-sulfur battery gel-state positive electrode and a preparation method thereof. The lithium-sulfur battery gel-state positive electrode comprises a gel layer, the gel layer is formed by fully swelling a polymer skeleton through an electrolyte, and the polymer skeleton is at least formed by blending a conductive polymer and an easy-to-gel polymer and then coating a supporting body with the mixture; and the electrolyte is at least formed by dissolving lithium polysulfide in a high dielectric constant solvent. The gel-state positive electrode has multiple advantages of high sulfur loading capacity, low electrolyte consumption, flexible and stable structure, effective sulfur species confinement, electron conduction and the like, various problems of sulfur insulation, expansion, dissolution, shuttling and the like are effectively solved, and the lithium-sulfur battery prepared from the gel-state positive electrode has high reversible specific capacity and actual specific energy, excellent cycling stability and good safety performance.

Description

technical field [0001] The invention belongs to the technical field of new energy, and in particular relates to a gel-state positive electrode of a lithium-sulfur battery and a preparation method thereof. Background technique [0002] Lithium-sulfur batteries have outstanding advantages such as high theoretical energy density, abundant raw material sources, and environmental friendliness. However, there are currently common defects such as low utilization of active materials, poor cycle stability, and serious self-discharge. This is mainly due to: 1) elemental sulfur and its The poor conductivity of solid-state discharge products leads to low electrochemical activity and serious polarization problems; 2) large volume changes of sulfur before and after lithiation lead to pulverization or even collapse of the electrode structure; 3) the formation of sulfur during charging and discharging The intermediate product lithium polysulfide is easily dissolved in the electrolyte and di...

Claims

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Application Information

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IPC IPC(8): H01M4/13H01M4/139H01M4/04H01M4/02H01M10/052
CPCH01M4/13H01M4/139H01M4/0404H01M4/02H01M10/052H01M2004/023Y02E60/10
Inventor 袁艳李正乾卢海郑东东刘漫博
Owner XI'AN UNIVERSITY OF ARCHITECTURE AND TECHNOLOGY