多孔纳米花状MoSe2 的1T/2H异相结和固态电解质包覆层协同改性硫正极的研究

缓慢的氧化还原反应动力学和穿梭效应等缺陷阻碍了锂硫电池实用化进程。异质（相）结被认为是一种具有较高催化活性的结构，但在锂硫电池催化效应中报道较少。围绕解决这一关键问题，本项目拟设计具有1T/2H异相结的多孔纳米花状MoSe2作为硫宿主材料，研究其改性锂硫电池动力学催化反应及对多硫化物穿梭效应的抑制效应；同时在MoSe2/硫材料表面引入固态电解质包覆层，进一步减弱多硫化物穿梭效应；运用同步辐射光电子能谱、球差校正透射电镜等表征手段研究1T/2H异相结界面对催化多硫化物转换的影响，并结合第一性原理计算阐明1T/2H异相结和固态电解质包覆层改善硫正极循环性能的内在原因。重点研究异相结&多孔纳米花状结构/固态电解质包覆层/电解液多相界面协同作用规律，并建立其相互作用机理模型，研究此协同效应与硫正极电池性能的内在关系，可望提出一种新颖的锂硫电池正极材料改性方案，加快推动锂硫电池的实用化进程。

Lithium sulfur batteries have been seriously hindered by the polysulfides shuttle effect and sluggish redox reaction kinetics. Heterostructures (heterophase junctions) are considered to be an effective sulfur host structure with high catalytic activity, but few papers were reported for the catalytic effects of lithium sulfur batteries. This project will design a porous flower-like nano molybdenum selenide with 1T/2H heterophase junctions as loading sulfur supporter to study the catalytic effect of the reaction kinetic, and the inhibition for the polysulfide shuttle effect. Meanwhile, introduced solid electrolyte coating layer via an atomic layer deposition (ALD) on the surface of molybdenum selenide/sulfur composite materials may further mitigate the polysulfides shuttle. Furthermore, using synchrotron radiation photoelectron spectroscopy and spherical aberration corrected transmission electron microscope will be focused on the effect of 1T/2H heterophase junctions on catalytic conversion of polysulfides. And the first-principles calculation will reveal the internal reasons for the performance improvement of sulfur cathode by 1T/2H heterophase junctions and solid electrolyte coating. The synergistic reaction mechanism of the multiphase interface composing of the heterophase junctions&porous flower-like nano structure-solid electrolyte coating layer-electrolyte will be a key focus, and its interaction mechanism model will be established. Moreover, the internal relationship between this synergistic effect and the electrochemical performance of the sulfur cathode will be studied. It is expected that this project may propose a new modification solution for sulfur cathode performance, which will promote the application of lithium sulfur batteries.