A preparation method of a polar lithium sulfide battery cathode sulfur-carrying material and a prepared lithium sulfide battery cathode sulfur-carrying material

Abstract

A preparation method of a polar lithium sulfide battery cathode sulfur-carrying material comprises that follow steps of: allowing an N-methyl pyrrolidone dispersion of an alkali metal elemental substance and a carbon nanotube with a solid content of 5 percent or an N-methyl pyrrolidone dispersion of an alkali metal elemental substance and a graphene with a solid content of 5 percent to react at amass ratio of 1:3-1:5 at the temperature of 140-180 DEG C for 2h, baking at 240 DEG C for 4h; And then calcining at 500-800 DEG C in N2 atmosphere in a tubular furnace. 4h, then performing washng withdilute hydrochloric acid and deionized wat successively; and obtaining a high specific surface area nitrogen-doped porous composite C by vacuum drying at 80 DEG C for 24 hours. The composite C and the sulfur powder are evenly mixed according to the mass ratio of 1: 3, and then kept at 155 DEG C for 10h and then at 300 DEG C for 1h to obtain the polar lithium sulfur battery cathode sulfur-carryingmaterial. The cathode sulfur-carrying material prepared by the invention has a network structure filled with porous amorphous carbon black between one-dimensional carbon conductive fibers or two-dimensional carbon conductive planes as a skeleton, has excellent conductive network, has high electric performance, and is simple in preparation process.

Description

technical field [0001] The invention relates to a preparation method of a positive electrode sulfur-carrying material of a polar lithium-sulfur battery and a positive-electrode sulfur-carrying material of a polar lithium-sulfur battery. Background technique [0002] Lithium-sulfur batteries have become a hotspot in the research of a new generation of high-energy lithium secondary batteries because of their high energy density. Compared with traditional lithium-ion batteries, lithium-sulfur batteries have obvious advantages, and are expected to replace conventional lithium-ion batteries as future high-energy-density, long-life secondary batteries. [0003] The development of lithium-sulfur battery technology faces many challenges. For example, elemental sulfur is an insulator with poor conductivity, which is not conducive to the transmission of electrons. Second, Li is generated during the discharge of the sulfur cathode 2 S n (n=4~8) and other high-order polysulfides will...

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Problems solved by technology

[0003] The development of lithium-sulfur battery technology faces many challenges. For example, elemental sulfur is an insulator with poor conductivity, which is not conducive to the transmission of electrons.

Second, Li is generated during the discharge of the sulfur cathode 2 S n (n=4~8) and other high-order polysulfides will dissolve into the organic electrolyte of lithium-sulfur batteries and migrate in the electrolyte, resulting in the loss of active materials and the destruction of the positive electrode structure, the expansion of the material shape, and the activity The substance detaches from the conductive agent after many cycles, which eventually leads to a decrease in cycle stability

Moreover, lithium polysulfide easily diffuses to the negative electrode during charging, and a self-discharge reaction occurs on the surface of the negative electrode lithium, and the self-discharged product migrates back to the positive electrode and is oxidized again. Reduced efficiency

[0004] At present, many studies are focused on compounding conductive carbon materials with sulfur to improve the performance of lithium-sulfur batteries. However, the hydrophobicity of carbon materials makes it difficult to adsorb lithium polysulfide, a positive discharge product with strong polarity, which affects the performance of batteries.

After the carbon material is modified by heteroatom doping, in addition to the physical adsorption of lithium polysulfide itself, the chemical adsorption capacity is increased due to the enhanced polarity, and the binding force with polysulfide is enhanced, which limits its "shuttle" in the positive and negative electrodes. effect"

Graphene nitride-sulfur composite S@NG prepared by Zhao Wei et al. (Nanoletters,2014,14(8): 4821-4827) and Wang Jian et al. (Journal of power source, 2016,321:193-200) The prepared N, S double-doped graphene showed good chemical adsorption capacity for polysulfides, but the materials prepared by the two had poor long-range electrical conductivity, which could not improve the electrical performance of lithium-sulfur batteries.

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