Lithium-sulfur secondary battery with high cycling stability and high coulombic efficiency

A lithium-sulfur secondary battery, cycle stability technology, applied in the direction of secondary batteries, secondary battery repair/maintenance, lithium batteries, etc., can solve the problems of positive electrode capacity attenuation, destruction of solid-phase reaction mechanism, etc., to achieve inhibition of dissolution, Improve the utilization rate and the capacity retention rate of lithium-sulfur batteries, and alleviate the effect of volume effect

Active Publication Date: 2021-05-14
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, studies have shown that S x Se y Te z @Polyacrylonitrile (x+y+z=1) is not compatible with the lithium metal negative electrode electrolyte system, and it will still produce soluble lithium polysulfide in the ether electrolyte, destroying the solid phase reaction mechanism and causing positive electrode capacity Severe attenuation (Weet.al., Metal-sulfur battery cathodes based on PAN-sulfur composites, J.Am.Chem.Soc.2015,137,12143)

Method used

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  • Lithium-sulfur secondary battery with high cycling stability and high coulombic efficiency
  • Lithium-sulfur secondary battery with high cycling stability and high coulombic efficiency
  • Lithium-sulfur secondary battery with high cycling stability and high coulombic efficiency

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0043] The lithium salt is lithium bisfluorosulfonimide, the ether compound is ethylene glycol dimethyl ether, and the compound containing a cyclic C=O structure is ethylene carbonate. Wherein, the concentration of lithium bisfluorosulfonyl imide is 1 mol / L, and ethylene carbonate accounts for 15 wt% of the total mass of ethylene glycol dimethyl ether and ethylene carbonate.

[0044] Use the above electrolyte, metal lithium negative electrode, vulcanized polyacrylonitrile positive electrode, and Celgard2400 diaphragm to assemble a lithium-sulfur battery. The specific operations are as follows:

[0045] Mix vulcanized polyacrylonitrile, carbon nanotubes and polyvinylidene fluoride uniformly in N-methylpyrrolidone at a mass ratio of 8:1:1 to obtain a slurry with a concentration of 30%;

[0046] The slurry was uniformly coated on carbon-coated aluminum foil, dried at 60°C for 12 hours, and then cut into discs with a diameter of 11mm for button batteries or pole pieces with a shap...

Embodiment 2～4

[0053] The assembly of the battery is similar to that of Example 1, the only difference being that the mass fraction of ethylene carbonate in the electrolyte is 5%, 10%, and 20%.

[0054] Under the condition of charge and discharge rate of 0.5C, the cycle performance test was carried out on the batteries respectively assembled with the electrolyte solutions provided in Examples 1 to 4, and the charge and discharge voltage curves were as follows: Figure 4 As shown in the figure, the mass fraction of ethylene carbonate is 5% and is recorded as EC05, and the mass fraction of ethylene carbonate is 10% and is recorded as EC10, and the mass fraction of ethylene carbonate is 15% and is recorded as EC15, and the mass fraction of ethylene carbonate is recorded as EC15. A score of 20% is recorded as EC20 (the same below). The charging and discharging voltage curves of the batteries assembled in each embodiment all present the characteristics of a single platform, indicating the effecti...

Embodiment 5

[0058] The assembly of the battery is similar to that of Example 1, the only difference being that the lithium salt in the electrolyte is lithium bistrifluoromethanesulfonylimide.

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Abstract

The invention discloses a lithium-sulfur secondary battery with high cycling stability and high coulombic efficiency. The lithium-sulfur secondary battery comprises a positive electrode, a negative electrode, a diaphragm and an electrolyte, wherein the electrolyte comprises a lithium salt, an ether compound and a compound containing a cyclic C=O structure; and a general formula of an active substance of the positive electrode is SxSeyTez@polyacrylonitrile, x+y+z=1, 0.6<=x<=1, 0<=y<=0.2, and 0<=z<=0.2. According to the lithium-sulfur secondary battery disclosed by the invention, the SxSeyTez@polyacrylonitrile is used as a positive electrode active material, and a novel ether-containing electrolyte matched with the SxSeyTez@polyacrylonitrile is developed, so that a solid-phase reaction mechanism in a sulfur conversion process is ensured, a shuttle effect is reduced, the loss of a sulfur positive electrode active material and the corrosion of a lithium metal negative electrode are greatly reduced, and the finally assembled lithium-sulfur secondary battery has excellent cycling stability and high coulombic efficiency.

Description

technical field [0001] The invention relates to the technical field of high specific energy secondary batteries, in particular to a lithium-sulfur secondary battery with high cycle stability and high coulombic efficiency. Background technique [0002] The theoretical specific capacity of lithium-sulfur battery is 2600Wh / kg. It is considered to be a promising next-generation high-energy lithium battery system, which is expected to solve the problems of "mileage anxiety" of new energy vehicles. The two-electron conversion process of sulfur in traditional lithium-sulfur batteries goes through the "solid-liquid-solid" reaction pathway. Due to the intrinsic electronic insulation of elemental sulfur and slow kinetic characteristics, it is usually necessary to introduce a conductive substrate (such as carbon) to form a composite positive electrode. In addition, chemical reactions inevitably occur between nucleophilic lithium polysulfide intermediates and electrophilic carbonates, s...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/60H01M10/0566H01M10/052H01M10/42
CPCH01M4/362H01M4/38H01M4/602H01M10/052H01M10/0566H01M10/4235H01M2004/028H01M2300/0025Y02E60/10
Inventor 陆盈盈沈泽宇
Owner ZHEJIANG UNIV
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