A lithium-sulfur secondary battery with high cycle 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 destroying the solid phase reaction mechanism, positive electrode capacity decay, etc., to improve the utilization rate and lithium-sulfur battery capacity retention, the effect of inhibiting dissolution and alleviating the volume effect

Active Publication Date: 2021-08-17
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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  • A lithium-sulfur secondary battery with high cycle stability and high coulombic efficiency
  • A lithium-sulfur secondary battery with high cycle stability and high coulombic efficiency
  • A lithium-sulfur secondary battery with high cycle stability and high coulombic efficiency

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

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

[0044] A lithium-sulfur battery is assembled using the above electrolyte, lithium metal negative electrode, sulfurized polyacrylonitrile positive electrode, and Celgard2400 separator. The specific operations are as follows:

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

[0046] The slurry was evenly coated on the carbon-coated aluminum foil, dried at 60°C for 12 hours, and then cut into a 11mm diameter disc for a button battery or a 43m...

Embodiment 2～4

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

[0054] Under the condition that the charge-discharge rate is 0.5C, the batteries assembled with the electrolyte solutions provided in Examples 1-4 were tested for cycle performance. The charge-discharge voltage curve is as follows: Figure 4 As shown in the figure, the mass fraction of ethylene carbonate is 5% as EC05, the mass fraction of ethylene carbonate is 10% as EC10, the mass fraction of ethylene carbonate is 15% as EC15, and the mass of ethylene carbonate A score of 20% was recorded as EC20 (the same below). The charge-discharge voltage curves of the batteries assembled in each example showed a single-platform feature, which indicated the effectiveness of ethylene carbonate in transforming the reaction mechanism of vulcanized polyacrylonitrile. However, when the mass fraction of ethylene carbonate is 5%, the ...

Embodiment 5

[0058] The assembly of the battery is similar to that of Example 1, except that the lithium salt in the electrolyte is lithium bis-trifluoromethanesulfonimide.

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Abstract

The invention discloses a lithium-sulfur secondary battery with high cycle stability and high coulombic efficiency, which includes a positive electrode, a negative electrode, a diaphragm and an electrolyte, the electrolyte includes lithium salts, ether compounds and cyclic C=O The compound of structure; The general formula of the active material of the positive electrode is S x Se y Te z @PAN, x+y+z=1, 0.6≤x≤1, 0≤y≤0.2, 0≤z≤0.2. The lithium-sulfur secondary battery disclosed by the present invention uses S x Se y Te z @Polyacrylonitrile is the positive electrode active material, and a new type of ether-containing electrolyte adapted to it has been developed to ensure the solid-state reaction mechanism during the sulfur conversion process, reduce the "shuttle effect", and greatly reduce the sulfur positive electrode activity The loss of material and the corrosion of lithium metal negative electrode. The final assembled lithium-sulfur secondary battery has excellent cycle 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 Patents(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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