Ionic polymer derivative carbon material used as lithium-sulfur battery positive electrode material

Abstract

An imidazolyl main chain ionic polymer and a carbon nanotube (CNT) are combined and used as a carbon material precursor, and a nitrogen-doped porous carbon (NPC)-coated three-dimensional high-conductivity multi-level hole carbon material linked and connected in series with a carbon nanotube in a seamless way is prepared. The high conductivity of a sulfur positive electrode material is ensured, theshuttling effect during the discharging process also can be effectively suppressed, so that relatively high sulfur utilization ratio and cycle stability are obtained. The preparation method comprisesthe steps of mixing the CNT and silicon dioxide in an organic solvent DMF, adding trimesic imidazole and triazine bromide to obtain an ionic polymer composite carbon nanotube material, performing high-temperature carbonization on the ionic polymer composite carbon nanotube material, and etching silicon dioxide with hydrofluoric acid to obtain a target composite material. The preparation method has a great expandable space, and a single-doped or jointly-doped material of various mixed elements can be easily achieved by exchanging counter negative ions in the ionic polymer to other target negative ions.

Description

technical field [0001] The invention relates to the technical field of lithium-sulfur batteries. More specifically, it relates to a preparation method and application of an ionic polymer-derived carbon material as a cathode material for a lithium-sulfur battery. Background technique [0002] With the rapid development of modern society, the ensuing energy shortage and environmental pollution have become major challenges faced by our country and even countries all over the world. Therefore, energy crisis and environmental pollution are problems that need to be solved urgently. Compared with traditional lithium-ion batteries, lithium-sulfur batteries have 1675mA h g -1 The theoretical specific capacity of lithium-sulfur batteries is five times that of traditional lithium-ion batteries, so lithium-sulfur batteries have become the focus of research and development of the next generation of high-energy-density lithium secondary batteries, but at the same time there are some prob...

AI Technical Summary

Problems solved by technology

Compared with traditional lithium-ion batteries, lithium-sulfur batteries have 1675mA h g -1 The theoretical specific capacity is 5 times that of traditional lithium-ion batteries, so lithium-sulfur batteries have become the focus of research and development of the next generation of high-energy-density lithium secondary batteries, but at the same time there are some problems that seriously restrict its commercial application

[0003] First of all, elemental sulfur is an insulator of electrons and ions, and active materials are difficult to use

In addition, lithium polysulfide, the intermediate discharge product of lithium-sulfur batteries, will dissolve in the electrolyte, resulting in the loss of active materials and shortening the battery life.

Moreover, the polysulfides dissolved in the electrolyte will migrate to the negative electrode and react with the metal lithium negative electrode, causing self-discharge and resulting in low Coulombic efficiency

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