Flaky MoS2-x coated hollow porous carbon sphere@sulfur composite material and preparation and application thereof

Abstract

The invention aims to provide preparation of a flaky MoS2-x coated hollow porous carbon sphere@sulfur composite material and application in a sulfur positive electrode of a lithium-sulfur battery. According to the S@C@MoS2-x composite material, the outer surface of the hollow porous carbon sphere material is coated with MoS2-x with flaky sulfur defects, sulfur is distributed in pores of a hollow carbon sphere cavity and a porous carbon layer, the content of carbon in the composite material is 5%-30%, the content of MoS2-x is 5%-30%, and the content of sulfur is 40%-90%. The cavities and rich mesoporous structures of the hollow porous carbon spheres provide sufficient sulfur fixation space, the utilization rate of active substances is ensured, meanwhile, infiltration of electrolyte is facilitated, and rapid conduction of ions and electrons under high multiplying power is met; more importantly, the flaky MoS2-x coating layers on the outer surfaces of the carbon spheres have relatively strong chemical adsorption and catalytic action on dissolved polysulfide, and the shuttling effect of lithium polysulfide can be effectively relieved in combination with the physical action of the carbon layers, so that the capacity retention ratio, the cycling stability and the rate capability of the battery are improved.

Description

technical field [0001] The invention belongs to the technical field of new energy, and in particular relates to a flake MoS 2-x Preparation of coated hollow porous carbon spheres@sulfur composites and their application in lithium-sulfur battery cathodes. Background technique [0002] With the progress and development of society, people are increasingly consuming non-renewable resources such as fossils, oil, and coal. In order to alleviate the dependence on non-renewable resources and promote the revolution of energy structure, people have accelerated the development and utilization of new energy. Among them, secondary batteries, as an important carrier, are playing an increasingly important role in the field of energy storage and reuse, such as stationary energy storage power stations, electric vehicles, etc. In secondary batteries, lithium-ion batteries have been widely used in energy storage fields such as small mobile power supplies and power batteries due to their advan...

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Problems solved by technology

However, the specific surface of the carbon spheres prepared in this patent is not high, and the carbon layer lacks enough pores to guide the immersion of sulfur. The distribution of sulfur in the hollow carbon sphere carrier is not uniform, and the chemical The adsorption is only a single-layer adsorption, and the anchoring effect on a large amount of dissolved lithium polysulfide is very limited, so the battery capacity retention rate is not high, and the long-term cycle performance is poor; in the Chinese patent with the authorized publication number CN108649194A, it is mentioned that graphene is used as a The substrate is loaded with molybdenum disulfide as the sulfur carrier to prepare the sulfur cathode composite material. The graphene with high specific surface can realize the high loading capacity of molybdenum disulfide and sulfur. Cycle stability of the battery

However, graphene in this patent is expensive, and it is difficult to achieve large-scale industrialization in terms of cost, and graphene lacks sufficient pore structure to physically limit lithium polysulfide. Single-layer chemical adsorption is difficult to efficiently fix a large amount of dissolved lithium polysulfide, so the capacity decay rate of the battery is relatively large under long-term cycles, and the retention rate is not high

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