A kind of preparation method of cathode material for lithium-sulfur battery and lithium-sulfur battery

Abstract

The invention relates to a preparation method of a positive electrode material of a lithium-sulfur battery. The preparation method comprises the following steps of enabling cobalt nitrate and 2-methylimidazole to be dissolved into a solvent and performing standing, centrifuging and drying to obtain ZIF-67; performing carbonization on ZIF-67 in inert atmosphere and performing cooling to the room temperature to obtain Co-N-C; and performing carbonization on Co-N-C and dicyandiamide in the inert atmosphere, and performing cooling to the room temperature to obtain CNT@ Co-N-C. The lithium-sulfur battery comprises the positive electrode material used for the lithium-sulfur battery. Beneficial effects are achieved as follows: compared with the single metal organic framework compound-based composite material, the specific surface area and the conductivity of the positive electrode material disclosed in the invention are enlarged and improved, and sulfur load can be realized more effectively;in addition, a shuttle effect of polysulfide in the battery reaction process can be suppressed more effectively; and a constant-current discharge test on the assembled battery proves that the electrochemical performance of the composite material with the carbon nanotubes in an in-situ growth manner is more excellent.

Description

technical field [0001] The invention relates to the technical field of energy storage, in particular to a preparation method of a cathode material for a lithium-sulfur battery and the lithium-sulfur battery. Background technique [0002] With the successful commercial application of graphite anodes, lithium-ion batteries have been widely used in portable electronic devices such as smartphones and laptops. After more than 20 years of development, the existing lithium-ion batteries based on lithium-intercalated compound cathodes are close to their theoretical capacity, but they still cannot meet the requirements of the rapidly developing electronics industry and emerging electric vehicles. Looking for batteries with higher energy density The system is imminent. For example, a lithium-sulfur battery is a new generation of lithium-ion secondary battery with metal lithium as the negative electrode and elemental sulfur as the positive electrode active material. Among them, metal ...

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Problems solved by technology

[0003] Although compared with traditional lithium-ion batteries, lithium-sulfur batteries have obvious advantages as mentioned above, but there are still problems such as low utilization of active materials, poor cycle performance, low Coulombic efficiency, and high self-discharge rate, which delays the pace of its practical application.

Li dissolved in organic electrolyte 2 S n (4≤n≤8) In the presence of a concentration gradient, it has been electrochemically oxidized in the electrolyte near the positive electrode to long-chain polysulfide lithium Li with a relatively long chain segment length 2 S n (6≤n≤8) diffuses to the lithium anode through the separator, and directly reacts with metallic lithium to generate short-chain polysulfide lithium Li with relatively short chain segment length 2 S n (4≤n≤6), Li 2 S 2 and Li 2 S, eventually leading to a decrease in the Coulombic efficiency of lithium-sulfur batteries

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