碳包覆金属氧化物纳米管以及硫填充复合材料的设计与电化学性能研究

Lithium-sulfur battery owing to its high lithium storage capacity could meet the requirements of rapid development of new energy technologies for high energy density batteries. However, due to the poor performances of current sulfur cathode material in storage capacity, cycling stability and rate performance, the development of the practical process of lithium-sulfur batteries is undoubtedly hindered. This proposal is intended to modify the sulfur cathode material by combination with metal oxide nanotube coated with carbon, the aim of which is to improve the sulfur efficiency and limit polysulfide dissolution, as well as enhancing hybrid conductivity. Therefore, lithium-sulfur cathode material of one-dimensional tubular structure nano-hybrid with excellent electrochemical performance and high stability could be obtained and meanwhile composition and structure of these materials could be controlled. By investigating the effect of phase composition, morphology and structure of sulfur/carbon/metal oxide hybrid on the electrochemical properties of lithium-sulfur cathode material, the intrinsic relationship between composition and structure parameters of carbon/metal oxide nanotubes hybrid and the electrochemical properties and electrochemical kinetics of lithium-sulfur cathode material could be clarified. In addition, the modification mechanism of metal oxide nanotubes/carbon hybrid on enhancing electrochemical performances of sulfur cathode could be revealed, so as to build a broad science base for application of new sulfur/carbon/metal oxide hybrid in high energy lithium-sulfur battery.

锂硫电池由于具有高的储锂能力，可以满足新能源技术飞速发展对高能量密度电池的需求。然而由于目前正极材料硫在比容量发挥、循环稳定性和倍率性能方面的表现并不理想，这无疑阻碍了锂硫电池向实用化发展的进程。本申请拟采用碳包覆金属氧化物纳米管复合材料对硫正极进行改性处理，目的是为了提高硫的利用率并限制多硫化物溶解，同时，增强复合材料导电性，从而获得电化学性能优异稳定的一维复合纳米管状结构的锂硫电池正极材料，且实现其微纳米结构参数的可控优化。通过对该硫/碳/金属氧化物复合材料的相组成、形貌和结构进行表征并对其用作锂硫电池电极材料时的电化学特性进行研究，揭示和阐明金属氧化物纳米管/碳复合体的组成结构参数与硫复合电极材料电化学性能及电化学动力学间的内在关系；并阐明金属氧化物纳米管/碳复合结构在增强硫电极电化学性能方面的改性机理，为新型硫/碳/金属氧化物复合材料在高能锂硫电池上的应用奠定材料科学基础。

本项目对碳/金属氧化物-硫三维复合材料的设计合成及其作为锂硫电池电极材料时的储能特性进行了研究。项目首先探索了不同结构参数碳/金属氧化物复合体的制备，在此基础上，利用水热和化学沉积法设计制备出6款碳/金属氧化物-硫复合电极材料，并对其电化学性能进行了系统研究和比较，从中筛选出1款高性能改善硫复合电极材料。在分析和比较所得硫碳复合材料微结构参数和电化学性能的基础上，探明了碳/金属氧化物复合体在改善单质硫电化学性能方面的作用机制。此外，还研究了复合材料石墨烯-MnO2-S复合材料的制备和电化学性能的研究。通过该项目实施，共发表SCI研究论文11篇，申请国家发明专利3项，培养研究生4名。本项目研究结果，为以硫碳金属氧化物复合体系为代表的正极材料在锂硫电池中的应用提供了可供借鉴的研究思路和实验方法，同时也为锂硫电池的发展提供一定促进作用。