Preparation And Chemical Performance Of Fiber-linked Nanoboxes Porous Carbon-based Membranes

Through continuous research on the lithium sulfur battery systems in recent years,the academic community is gradually mining the various potentials of lithium sulfur batteries and constantly pushing their energy density and charge discharge performance to a higher level.But there are still many inherent limitations on the road to the continued development and further commercialization applications of lithium sulfur batteries.Previous related researches and reports on carbon based integrated positive electrode for lithium sulfur batteries were proposed:improving and improving the performance of materials in battery cycling can be achieved by elevating the adsorption and catalysis of materials to battery cycling products,constructing controllable high specific surface area structures in combination with the characteristics of highly conductive materials,and so on.At the same time,how to combine the delicate three-dimensional structure design with multiple advantages such as targeting the chemical composition to enhance the catalytic efficacy of adsorption is also one of the hot issues of research at present.In this paper,from the side of the positive electrode of lithium sulfur batteries,carbon based positive electrode materials are prepared by electrospinning method,and its design is studied but the preparation method is simple,and it has a certain significance for the practical application of lithium batteries.The high-performance porous,and necklace-like Fe₃C/N-codoped carbon nanoboxes membrane（Fe₃C/NC）was fabricated by a well-established electrospinning process,an exquisite three-dimensional hollow structure with uniform distribution of iron and nitrogen atoms in it could largely suppress the shuttle effect while providing a large number of polysulfide binding sites,and this synergistic catalysis guaranteed good charge discharge performance of lithium sulfur batteries.The highly conductive carbon fiber stacking structure of the membrane itself is well tolerated to volume change.The materials proposed in this work have several advantages in terms of structure and chemical composition,which can simultaneously improve the shuttle effect,conductivity,and volume expansion effect existing within the system and optimize the electrochemical reaction kinetics.Meanwhile the constructed polysulfide trapping adsorption network writ its application prospect for high sulfur loading.Exhibited a high capacity of 645 m Ah g^-1 after 240 cycles at 1 C.Even after 100 cycles at 0.2 C at a high sulfur loading of 5 mg cm^-2,a high capacity of 712 m Ah g^-1 was still achieved.In order to further explore the reason why the Fe₃C/NC cathode has excellent omni-directional electrochemical performance,based on the above research,this paper simulated and confirmed the complex multi-step electrochemical reaction in Li-S battery by VASP based on the first principles.The simulation results show that the N-doped sites can bond with polysulfides to form a more stable adsorption structure and exhibit catalytic activity.The highest electrocatalytic activity was observed on the surface of Fe₃C（220）.The codoped materials can make the conversion of S₈ to Li₂S into a spontaneous exothermic process,resulting in the optimal electrochemical performance.In this paper,the high electrochemical performance of the material was studied from two aspects of experimental electrochemical performance and theoretical electrochemical reaction mechanism,which provided a new idea for the construction of high performance lithium sulfur battery cathode.