A composite material of multi-stage pore carbon and cobalt sulfide, preparation method thereof and lithium sulfide battery cathode material containing composite material and lithium sulfide battery

Abstract

The invention relates to a composite material of multi-stage pore carbon and cobalt sulfide, a preparation method thereof, a lithium sulfide battery cathode material containing the composite materialand a lithium sulfide battery, and belongs to the field of energy storage batteries. The preparation method of the composite material comprises the follow steps: (1) dispersing multi-stage pore carbonin a strong acid solution, connecting a carboxyl group with the multi-stage pore carbon or dispersing the multi-stage pore carbon in the strong alkali solution, connecting a hydroxyl group with the multi-stage pore carbon, obtaining functionalized multi-stage pore carbon, cleaning the functionalized multi-stage pore carbon to neutrality, and drying the functionalized multi-stage pore carbon; wherein the multi-stage porous carbon has micropores, mesopores and macropores. The specific surface area of multi-stage porous carbon is 1981 - 2400m2 / g, and the total pore volume is 1.72 - 2.24 cm3 / g; and (2) dispersing the dried functionalized multi-stage porous carbon obtained in the step (1) in water or an organic solvent miscible with water, ultrasonicating, adding a cobalt source and a sulfur source, and carrying out hydrothermal reaction to obtain a multi-stage porous carbon and cobalt sulfide composite material. The composite material of the invention is applied to a lithium sulfur battery and has excellent electrochemical performance.

Description

technical field [0001] The invention relates to a composite material of hierarchical porous carbon and cobalt sulfide, a preparation method thereof, and a lithium-sulfur battery positive electrode material and a lithium-sulfur battery containing the composite material, which belong to the field of energy storage batteries. Background technique [0002] In recent years, new energy vehicles, portable storage, energy storage power stations and many other fields have put forward higher energy density application requirements for energy storage devices, and the existing lithium-ion batteries are close to their energy density limit, so there is an urgent need for high energy density storage. A major technological innovation in the energy system. Due to its theoretical energy density (2500Wh·kg -1 ) ultrahigh, low cost of raw materials, good environmental adaptability and other advantages are regarded as one of the high energy density systems most likely to be practical. However,...

AI Technical Summary

Problems solved by technology

However, lithium-sulfur batteries also face many challenges: the poor conductivity of sulfur, the reaction intermediate polysulfides are easily dissolved in the electrolyte and produce a shuttle effect, there is a large volume change during charge and discharge, and there are high sulfur ratios and sulfur-loaded cathodes. Insufficient capacity, etc.

These problems have seriously affected the capacity retention and life of lithium-sulfur batteries.

Generally speaking, loading sulfur into porous carbon materials is a common method to alleviate the capacity decline caused by the shuttle effect and volume expansion, but there are also certain problems: first, the preparation process of the carbon materials reported so far is generally relatively complicated, The reproducibility rate is low and there are certain problems in batch preparation. Second, carbon materials without any modification have insufficient adsorption capacity for polysulfides and are easy to fall off, resulting in aggravated capacity fading.

The specific surface area of ​​the composite material of two-dimensional graphene and vanadium sulfide is obviously very small, which is not conducive to the deposition of lithium sulfide during the discharge process.

The patent application with publication number 106374087A discloses a positive electrode material for long-cycle lithium-sulfur batteries and its preparation method. This technology uses one-dimensional and two-dimensional carbon materials to be composited with metal oxides or metal sulfides. This solution is more technical. 3 There are certain improvements, but there are still some problems: firstly, the price advantage of these carbon materials is not obvious, and graphene oxide and carbon nanotubes that are not easily dispersed are used; secondly, these carbon materials are compounded with metal oxides or metal sulfides For the dissolution of polysulfides, there is only chemical adsorption, and in theory, this composite material is relatively dense, which is not conducive to loading an excessively high ratio of elemental sulfur

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