硫在共轭微孔聚合物/碳纳米管复合材料中的高效负载及在高性能锂-硫电池正极材料中的应用

To prepare high-performance cathode materials for lithium-sulphur batteries, in this proposal, we are aimed to combine conjugated microporous polymers (CMPs) and carbon nanotubes (CNTs) to make CMP/CNT composites having multi-scaled pores, followed by incorporating sulphur into the composites. The sulphur-incorporated CMP/CNT composites are featured with multi-scaled porous structures, high-sulphur content, excellent electrochemical activity, and good electrical conductivity so that the performances of the resultant Li-S batteries are enhanced. In this project, a novel idea that utilizes CMP/CNT composites having multi-scaled pores to carry sulphur as cathode materials for Li-S batteries is proposed. By controlling the size of sulphur particles and the interactions between sulphur and CMP/CNT matrix, not only the problems such as the shuttling effects of the polysulfides and the volumetric changes of the electrode materials are avoided, but also the critical issues such as the low electrical conductivity of common sulphur-incorporated materials can be solved and the kinetics of the lithiation/delithiation processes are promoted. As a result, the electrochemical performances of the Li-S batteries prepared with the aforementioned materials will be significantly improved. In addition, the proposed method for synthesizing the sulphur-incorporated CMP/CNT composites is facile and environment-friendly. Finally, this project will offer a new idea for the synthesis of cathode materials for Li-S batteries, and the new sulphur-incorporated CMP/CNT composites are significantly important in the areas of functional polymeric composites and energy storage/conversion materials.

针对制备高性能锂-硫电池正极材料这一研究课题，本项目拟将共轭微孔聚合物（CMPs）与碳纳米管（CNTs）复合得到具有多重孔结构的CMP/CNT复合材料，再将硫负载于CMP/CNT中，制备同时具有高硫负载量、多重孔结构、优异电化学活性、优异导电性的负载硫的CMP/CNT复合材料，从而提升锂-硫电池的性能。本项目提出了在具有多重孔结构的CMP/CNT中负载硫来制备锂-硫电池正极材料的新思路，通过对硫颗粒尺寸及硫和CMP/CNT基体间作用的调控，既避免了电池在充放电过程中多硫化物的穿梭效应、电极材料体积膨胀的难题，又解决了电极材料导电性差的关键问题，还促进了硫的锂化和脱锂过程的动力学，从而提高材料在锂-硫电池应用中的性能。本项目提出的负载硫的CMP/CNT复合材料制备过程简单、条件温和，为锂-硫电池正极材料的设计和制备提供了新思路，在功能聚合物复合材料和能源材料技术领域都有重要的研究价值。

硫的储锂容量高、价格低廉、环境友好，因此锂硫电池有望成为下一代高能量密度能源存储器件。然而，硫正极缓慢的反应动力学、多硫化物的穿梭效应限制了锂硫电池的应用和发展，硫载体材料设计是解决上述问题的关键。本项目通过共轭微孔聚合物（CMPs）分子结构的设计及与碳材料的复合，提出了多种解决上述问题的技术方案，并针对硫正极电化学过程的机理进行了深入解析。在材料设计上，取得了以下重要成果：（1）提出了使用有机配体为单体进行聚合物合成，得到了含Co单原子催化剂的CMPs；（2）基于多壁碳纳米管（MWNTs）的修饰，实现了CMPs合成过程中在MWNTs表面的接枝，得到了具有MWNTs核、CMPs壳的复合物材料；（3）通过共轭聚合物聚三己基噻吩（P3HT）在氧化石墨烯还原产物（RGO）表面的原位生长，得到了具有分子刷结构的P3HT@RGO复合物，并利用P3HT分子链的物理交联作用，得到了具有大孔结构的复合物材料。在上述工作的基础上，开展了锂硫电池制备、表征等研究工作，并针对材料结构与器件性能之间的关系进行了深入讨论。最后，针对上述硫载体材料中Co单原子催化剂的催化机理，采用理论计算和X射线近边吸收等手段进行了系统、深入的解析。本项目提出的制备硫载体材料的技术方案，为锂-硫电池正极材料的设计和制备提供了新思路，在功能聚合物复合材料和能源材料技术领域都有重要的研究价值。