Positive electrode of lithium-sulfur battery and preparation method of positive electrode

Abstract

The invention discloses a positive electrode of a lithium-sulfur battery and a preparation method of the positive electrode. The positive electrode is composed of an aluminum foil and a coating layer arranged on the surface of the aluminum foil, wherein the coating layer is of a multilayered structure and is composed of elemental sulfur, a conducting agent and a binding agent; the sulfur content in all layers of the multilayered structure is distributed in a gradient shape from inside to outside; the sulfur content of the innermost layer is the highest and the outermost layer does not contain the sulfur. According to a gradient multilayered sulfur positive electrode structure provided by the invention, the innermost layer takes a carbon material with a high specific surface area and a high adsorption capability as the conducting agent and the sulfur fixation effect is enhanced; polysulfide ions can be adsorbed in the electrode as much as possible so that dispersion of the polysulfide ions toward a negative electrode side is alleviated; a surface containing does not contain a sulfur material and a sulfur diffusion space is provided; the planar carbon material is adopted so that the blocking effect on lithium polysulfide is enhanced; the lithium polysulfide is limited in an electrode space as much as possible, so that the structure provided by the invention can improve the circulating performance of the sulfur electrode to a certain extent.

Description

technical field [0001] The invention relates to the technical field of chemical power sources, in particular to a method for manufacturing a positive electrode of a lithium-sulfur battery. Background technique [0002] Lithium-sulfur battery is a high-energy-density chemical power source that has been researched very hotly in recent years. If elemental sulfur is used as the positive electrode and metallic lithium is used as the negative electrode, according to the final reduction reaction product Li 2 S calculation, the theoretical energy density of the Li / S redox pair is as high as 2600Wh / kg, and the actual energy density can even reach more than 500Wh / kg, which is significantly higher than that of general commercial secondary batteries. [0003] The discharge of sulfur in the positive electrode of lithium-sulfur batteries mainly goes through two stages. The first stage: reduction of sulfur to generate soluble lithium polysulfide Li 2 S 8 , which is further transformed ...

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Problems solved by technology

[0006] The purpose of the present invention is to solve the problem of active material loss and rapid capacity decay caused by the diffusion of the intermediate active substance lithium polysulfide dissolved by the positive electrode sulfur material discharge to the outside of the electrode, the depth of the electrolyte, and even the direction of the negative electrode. Starting from the internal structure of the electrode, Appropriate electrode structure and construction of conductive framework are adopted to alleviate the dissolution and diffusion of discharge intermediate products of sulfur cathode and control the localization of sulfur to improve the cycle performance of sulfur cathode

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