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A kind of lithium-sulfur battery positive electrode and its manufacturing method

A lithium-sulfur battery and cathode technology, which is applied to the lithium-sulfur battery cathode and its manufacturing field, can solve problems such as affecting electrode reaction, increasing ion transmission resistance, internal self-discharge, etc., so as to shorten the ion transmission path, improve the charge conductivity, improve Effects of interface properties

Active Publication Date: 2020-12-25
XI'AN UNIVERSITY OF ARCHITECTURE AND TECHNOLOGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, at this stage, the battery still has defects such as low utilization rate of active materials, short cycle life, poor rate performance, and serious self-discharge, which has seriously hindered its development since its introduction in the 1960s. The main reasons are as follows: :
[0003] 1) Elemental sulfur and its reduction products are electron and ion insulators at room temperature, which affect the conversion and utilization of materials;
[0004] 2) The volume continuously expands / shrinks during sulfur lithiation / delithiation, causing instability or even failure of the electrode structure;
[0005] 3) A series of intermediate polysulfides formed during charging and discharging are easily dissolved in the electrolyte and diffuse to the negative electrode to form a shuttle effect, causing a series of problems such as loss of active materials, corrosion of metal lithium, internal self-discharge, and deposition of insulating products
[0006] To this end, the researchers compounded elemental sulfur with various porous carbons with high specific surface area and high conductivity to enhance the conductivity of the positive electrode. At the same time, the porous carbon was used to confine the active material. Dissolution is still inevitable
There is also a coating structure on the surface of the positive electrode to physically block polysulfides by using the coating. However, if the coating is too dense or too thick, it will hinder the penetration of the electrolyte, increase the ion transmission impedance, and affect the electrode reaction.
Moreover, the coating cannot fully adapt to the volume deformation of the electrode, and may fall off during battery cycling.
In addition, since the dissolution and shuttling of polysulfides both occur in the electrolyte, polysulfides can also be better restricted by using gel electrolytes, but most gel electrolytes only have ion conductivity and no electronic conductivity, and It belongs to a two-phase system with the positive electrode, and there are hidden dangers in the contact resistance and interfacial compatibility of the electrolyte / positive electrode

Method used

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  • A kind of lithium-sulfur battery positive electrode and its manufacturing method
  • A kind of lithium-sulfur battery positive electrode and its manufacturing method
  • A kind of lithium-sulfur battery positive electrode and its manufacturing method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0043] The sulfur-carbon composite material, conductive agent and binder were mixed in NMP at a mass ratio of 8:1:1, coated on an aluminum foil, and vacuum-dried at 50° C. for 48 hours to obtain a sulfur-containing active material layer.

[0044] Mix PVDF-HFP, PVP, and nano-carbon black in DMF solvent at a mass ratio of 10:4:1, and coat it on the above-mentioned sulfur-containing active material layer with a thickness of about 50um, and let it stand in the air for 2h. Then vacuum-dry at 50° C. for 48 hours to obtain a composite film layer.

[0045] In the glove box, soak the composite film layer in the electrolyte at 25°C for 12h (the electrolyte composition is 1mol / L LiTFSI and 0.1mol / L LiFSI dissolved in a mixed solvent of DME and DOL with a volume ratio of 1:1) , to prepare a gel electrolyte layer and a lithium-sulfur battery positive electrode carrying the gel electrolyte layer.

[0046] In the glove box, the above-mentioned positive electrode, polypropylene separator and...

Embodiment 2

[0053] The sulfur-containing active material layer is the same as in Example 1.

[0054] Mix PEO, PEDOT / PSS in deionized water at a mass ratio of 5:1, and coat it on the sulfur-containing active material layer with a thickness of about 20um. After vacuum drying at 70°C for 24 hours, a composite film layer and a composite film layer are prepared. Membrane lithium-sulfur battery positive electrode.

[0055] In the glove box, the above-mentioned positive electrode, polypropylene separator and metal lithium sheet were stacked sequentially, and an appropriate amount of electrolyte was added dropwise on the surface of the positive electrode composite film layer and the surface of the separator (the electrolyte composition was 1mol / L LiBETI and 0.1mol / L LiNO 3 Dissolved in a mixed solvent of ionic liquid Py14TFSI and DOL with a volume ratio of 7:3), quickly sealed in a button case and assembled into a lithium-sulfur battery. The battery was further gelled at 80° C. for 0.5 h.

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Abstract

A lithium sulfide battery cathode and a manufacturing method therefor are disclosed. A gel electrolyte layer composed of a polymer matrix, a conductive filler and an electrolyte is coated on the surface of a cathode sulfide-containing active material layer, so that the gel electrolyte layer has both ionic conductivity and electronic conductivity. The lithium-sulfur battery cathode fully combines the advantages of a coating positive electrode and a gel electrolyte, and at the same time, the defects of the coating positive electrode and the gel electrolyte are abandoned as far as possible, thereby contributing to the establishment of a stable and efficient lithium-sulfur battery system, and comprehensively improving the performance of the battery, such as capacity, cycle, multiplying power and the like.

Description

technical field [0001] The invention belongs to the technical field of new energy, and in particular relates to a positive electrode of a lithium-sulfur battery and a manufacturing method thereof. Background technique [0002] Lithium-sulfur batteries have the advantages of high energy density, environmental friendliness, and abundant sources of raw materials. They have become one of the energy storage devices with great development potential, and have attracted extensive research and attention from researchers all over the world. However, at this stage, the battery still has defects such as low utilization rate of active materials, short cycle life, poor rate performance, and serious self-discharge, which has seriously hindered its development since its introduction in the 1960s. The main reasons are as follows: : [0003] 1) Elemental sulfur and its reduction products are electron and ion insulators at room temperature, which affect the conversion and utilization of mater...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/13H01M4/139H01M10/052
CPCH01M4/13H01M4/139H01M10/052Y02E60/10
Inventor 袁艳郑东东方钊卢海刘漫博
Owner XI'AN UNIVERSITY OF ARCHITECTURE AND TECHNOLOGY
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