基于空心碳球的三维多孔微纳结构的构建及其在高硫负载量锂硫正极材料中的应用

Developing the sulfur cathode materials with excellent electrochemical performance, high sulfur loading and good compatibility with traditional slurry-casting protocol is one of the key to promote the practical application of the high energy density lithium-sulfur battery. Both nano-structured sulfur/carbon cathode and self-supporting structured sulfur/carbon cathode has its own disadvantage, and architecting the nano-carbons as micro-nano structures for sulfur cathode could not only keep the merit of the nanostructure but also realize high sulfur loading, which has the most potential to accomplish all the goals above. Hollow carbon nano-sphere/sulfur cathodes reported in literatures demonstrate excellent electrochemical performance but have low sulfur loadings, in order to avoid the above shortage, we propose to design novel hollow carbon sphere-based three dimensional porous micro-nano structures for sulfur cathode. Based on previous experiments, this study aims to construct the hollow carbon sphere-based three dimensional porous micro-nano structures via hydrothermal or in-situ catalysis growth methods, to investigate their formation mechanism and provide guidance for the design and construction of the hollow carbon sphere-based micro-nano structures; we’ll illustrate the relationship between the cathode structure and the sulfur loading, and study the electrochemical behaviors and failure mechanism of the micro-nano structure cathodes with high sulfur loadings. Those explorations may provide theoretical guide for the regular design and application of the micro-nano carbon/sulfur cathode with high sulfur loading and long cycle life for lithium sulfur batteries, and also spread the applications of these micro-nano structures on other electrode materials.

发展具有良好电化学性能、高硫负载量同时兼顾低成本浆料涂覆工艺的锂硫正极材料是推动高能量密度锂硫电池实用化的关键之一。纳米硫碳正极和自支撑硫碳正极都各具缺点，而将纳米碳材料构建为微纳结构硫正极既保持了纳米结构的优势又能够实现高硫负载量，最具有同时实现上述目标的潜力。文献报道的纳米空心碳球硫正极电化学性能优异但普遍硫负载量偏低，为克服以上不足，我们提出了构建新颖的基于空心碳球的三维多孔微纳结构硫碳正极的思路。本课题在前期实验基础上，探索通过水热自组装和原位催化生长等方式构建三类基于空心碳球的三维多孔微纳结构，研究其形成机制，指导基于空心碳球的微纳结构的设计和构建；探讨微纳硫碳正极结构与硫负载量之间的关系，研究其在高硫负载量时的电化学行为和性能衰减机制，为高硫负载量、长循环寿命微纳结构硫碳正极材料的规律性设计和应用提供理论指导，拓展上述三维多孔微纳结构在其它电极材料中的应用。

发展具有良好电化学性能、高硫负载量同时兼顾传统电池制造工艺的锂硫正极材料是推动高比能锂硫电池实用化的关键之一。将纳米碳材料构建为微纳结构硫正极是一种有效的途径。本课题以SiO2@RF纳米球为前驱体基元，通过氧化石墨烯水热自组装和固态有机物碳源原位催化生长成功构建和制备了三类结构新颖的3D HCS-rGO、3D HCS-CNT和3D p-Graphene碳基微纳结构，阐明了氧化石墨烯和SiO2@RF纳米球水热自组装以及固体有机碳源和过渡金属原位催化生长机制；通过模板和造孔剂制备了高孔隙率、高比表面积的三维蜂窝碳材料、通过乙醇镀碳制备了高孔体积、壁厚可控的中空纳米碳泡沫，明确了微纳碳结构的孔结构、表面结构以及载硫方式等与硫正极的电化学性能之间的关系，初步揭示了高孔体积、高导电性和三维导电网络结构对高硫负载、高硫面密度硫正极电化学活性和稳定性的协同作用，在硫含量90%以上、硫面密度6.9mg/cm2的高硫载量下，实现了锂硫软包电池放电容量1100mAh/g以上、能量密度382Wh/kg、稳定循环40次，为高硫负载量、长循环寿命的微纳结构硫碳正极材料的规律性设计和应用提供了理论指导。项目资助发表高水平SCI论文7篇，申请国家发明专利5项，授权4项，进行国际国内学术会议交流3次。培养硕士生3名，其中1名已经取得硕士学位，2名在读。项目资助经费21万元，支出10.5784万元，剩余经费10.4215万元，剩余经费计划用于本项目研究后续支出。