Preparation method and application of double-carbon-layer-coated nitrogen-doped polysulfide

Abstract

The invention provides a double-carbon-layer-coated nitrogen-doped polysulfide, and belongs to the field of new energy storage materials. The crystal shape of the double-carbon-layer-coated nitrogen-doped polysulfide is a cube, the molecular formula of the double-carbon-layer-coated nitrogen-doped polysulfide is Fe4.005Ni4.995S8@NDC, and under double-carbon-layer coating, the double-metal sulfide Fe4.005Ni4.995S8 is in the shape of a round particle with an intact structure. The Fe4.005Ni4.995S8@NDC prepared by the preparation method disclosed by the invention is good in electrochemical performance, remarkable in dual-carbon coating effect, good in crystallinity and high in intrinsic reaction activity; and the Fe4.005Ni4.995S8@NDC has high cycle and rate performance when being applied to a lithium-air battery, and the preparation method is one-step calcination and is suitable for large-scale production.

Description

technical field [0001] The invention relates to the field of new energy storage materials, in particular to a Fe 4.005 Ni 4.995 S 8 @NDC positive electrode catalytic materials and their preparation methods and applications. Background technique [0002] Lithium-air batteries provide a new solution for the development of next-generation energy storage and conversion devices. The system has a high theoretical energy density (~3500Wh kg -1 ), not only 10 times the energy density of traditionally used lithium-ion batteries, but even comparable to gasoline. However, the cycle life, reaction kinetics, and cycle efficiency of the battery are seriously hindered by the influence of many side reactions in the system. Therefore, in recent years, a large number of researchers have devoted themselves to designing a highly efficient cathode catalyst in order to reduce the overpotential of the system and inhibit the occurrence of side reactions. [0003] The development of a reasonabl...

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Problems solved by technology

[0004] However, the energy storage performance of most lithium-air batteries currently developed is still difficult to meet people's needs, such as low cycle life, large overpotential, and nucleophilic attack by singlet oxygen.

[0005] For example, comparative literature 1 (Metal-organic framework-derived cobalt nanoparticlespace confined in nitrogen-doped carbon polyhedra networks as high-performance bifunctional electrocatalyst for rechargeable Li–O 2 The Co@NC cathode material described in batteries, Shun-zhi Yu et al., Journal of Power Sources 453(2020) 227899) does not adopt any method that can improve the intrinsic conductivity of the material, and the material in Reference 1 has no core The protection of the shell structure is difficult to resist the attack of superoxide radicals in the reaction, which makes the cycle life decay rapidly

[0006] As another example, in comparative literature 2 (Nitrogen-Coordinated CoS2@NC Yolk-Shell PolyhedronsCatalysts Derived from a Metal-Organic Framework for a Highly Reversible Li-O 2 Battery, Yang Zhan et al., ACS Appl.Mater.Interfaces 2021, 13, 17658-17667), although vulcanization treatment has been carried out to improve the intrinsic reactivity of the material, but due to its irregular morphology, it cannot resist the OER / The external mechanical stress in the ORR process makes its morphology not well maintained

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