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Multifunctional binder for lithium-sulfur battery positive electrode and preparation method of multifunctional binder

A lithium-sulfur battery, multi-functional technology, applied in the direction of battery electrodes, lithium batteries, non-aqueous electrolyte battery electrodes, etc., can solve the problem of volatile solvent biotoxicity, unfavorable environmental protection, inability to effectively inhibit the shuttle effect, and high boiling point that is difficult to remove. and other issues, to achieve the effect of improving cycle specific capacity and cycle stability, inhibiting the shuttle effect, and improving cycle stability

Active Publication Date: 2020-09-01
SUN YAT SEN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] At present, polyvinylidene fluoride (PVDF) is mainly used as the binder for the positive electrode of lithium-sulfur batteries. It is a semi-crystalline polymer with low bonding strength. Inhibit the shuttling effect, resulting in low cycle stability
In addition, when using PVDF, it is necessary to use N-methylpyrrolidone (NMP) as the solvent to prepare the positive electrode material. NMP not only has a high boiling point and is difficult to remove, it takes a long time to dry and consumes a lot of energy, and it is easy to lose sulfur active substances during the drying process. The biological toxicity of the solvent is not conducive to environmental protection

Method used

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  • Multifunctional binder for lithium-sulfur battery positive electrode and preparation method of multifunctional binder
  • Multifunctional binder for lithium-sulfur battery positive electrode and preparation method of multifunctional binder
  • Multifunctional binder for lithium-sulfur battery positive electrode and preparation method of multifunctional binder

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Experimental program
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Effect test

Embodiment 1

[0058] The preparation of embodiment 1 polyrotaxane

[0059] In order to improve the reactivity of polyethylene glycol terminal hydroxyl groups, first modify polyethylene glycol to polyethylene glycol diamine, the process is: weigh 8.0g polyethylene glycol (Mn=8,000g / mol) and 0.2g Add N,N'-dicarbonylimidazole to 100mL tetrahydrofuran and react at 50°C for 18h, then weigh 0.54g of ethylenediamine and add it to the reaction system, keep it warm for 2h, add 40mL of ethanol to the product and place it in the refrigerator Precipitate after standing for 2 hours, wash the product with refrigerated ethanol, and dry for 48 hours to obtain polyethylene glycol diamine.

[0060] Weigh 10g of α-cyclodextrin and slowly add it to 20mL of deionized water, heat to 80°C, after the α-cyclodextrin is completely dissolved to obtain a transparent solution, then add 1.0g of the above polyethylene glycol diamine, keep stirring for 30min , put the mixed solution at low temperature (5-10°C) and refrig...

Embodiment 2

[0061] The preparation of embodiment 2 cationic polyrotaxane

[0062] Weigh 1.0 g of the polyrotaxane obtained in Example 1 and dissolve it in 100 mL of NaOH solution with a concentration of 1 mol / L. After dissolving in an ice bath to obtain a yellow, uniform and transparent solution, add 5.0 g of 2,3-epoxypropyl tris Methyl ammonium chloride, stirred and reacted for 12 hours, the product was dialyzed with deionized water and freeze-dried to obtain a cationic polyrotaxane. cationic polyrotaxane 1 See attached for H NMR spectrum figure 1 . Depend on figure 1 It can be seen that compared with Example 1, the nuclear magnetic spectrum of Example 2 shows that the chemical shift is 3.15 in the -CH in the quaternary ammonium salt group. 3 proton signal, indicating the successful preparation of cationic polyrotaxane.

Embodiment 3

[0064] This embodiment provides a multifunctional binder for the positive electrode of lithium-sulfur battery, and provides the positive electrode of lithium-sulfur battery prepared by the multifunctional binder, and the assembled lithium-sulfur battery.

[0065] Preparation of multifunctional binder: Weigh 80 parts of polyacrylic acid (number average molecular weight 400kDa) into DMSO solvent, add 0.01 part of N,N-dicarbonyl imidazole, stir at 50°C for 12h, then weigh polyrotaxane 5 parts and 15 parts of cationic polyrotaxane were added to the above reaction solution, stirred for 72 hours, and the obtained product was a multifunctional binder for positive electrodes of lithium-sulfur batteries.

[0066] Preparation of the positive electrode: weigh the composite of sulfur / carbon black, conductive agent and binder according to the ratio of 8:1:1 by mass, add deionized water after grinding for 0.5h, stir to form a uniform slurry, and put The slurry was coated on carbon-coated al...

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Abstract

The invention discloses a multifunctional binder for a lithium-sulfur battery positive electrode and a preparation method of the multifunctional binder. The multifunctional binder is mainly prepared from the following raw materials in parts by weight of 50-99 parts of polyacrylic acid; 0 to 30 parts of polyrotaxane; 1 to 30 parts of cationic polyrotaxane; 0.01 to 1 part of a cross-linking agent, the cross-linking agent contains at least two reaction groups, at least one reaction group reacts with the carboxyl of the polyacrylic acid, and at least one reaction group reacts with hydroxyl of cyclodextrin in the polyrotaxane and the cationic polyrotaxane. The multifunctional adhesive disclosed by the invention shows the excellent mechanical strength and elasticity, can effectively protect thestructure stability of a sulfur positive electrode, can efficiently absorb the polysulfide in the lithium-sulfur battery so as to inhibit the shuttle effect caused by the polysulfide, can effectivelyimprove the cycle specific capacity and the cycle stability of the lithium-sulfur battery, and is green and environment friendly, and has the very good application value.

Description

technical field [0001] The invention relates to the technical field of secondary battery materials, and more specifically, relates to a multifunctional binder used for the positive electrode of a lithium-sulfur battery and a preparation method thereof. Background technique [0002] Rechargeable batteries (secondary batteries) are widely used in automobiles, electronics, communications and other fields. Research and development of new materials to improve battery capacity and prolong service life are of great significance to the development of this field. Lithium-sulfur batteries have excellent energy density (2,060Wh / kg) and theoretical specific capacity (1,675mAh / g). The positive electrode uses sulfur as the active material, which has the advantages of low cost, low specific gravity and low toxicity. Lithium-sulfur batteries are easy to prepare and are expected to meet people's increasing demand for new energy batteries, and have received widespread attention in recent year...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/62H01M4/13H01M10/052
CPCH01M4/13H01M4/622H01M4/628H01M10/052Y02E60/10
Inventor 容敏智谢振华章明秋
Owner SUN YAT SEN UNIV
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