基于碳纳米管宏观体的高性能锂硫电池体系研究

Lithium-sulfur battery has advantages of high theoretical energy density, low cost, and environmental benignity, and is considered as one of the most promising next-generation rechargeable batteries. However, due to the low conductivity of sulfur and lithium sulfide, the volume variation and instability of the electrode structure, the dissolution and migration of polysulfides, and the growth of lithium dendrite during cycling, lithium-sulfur battery has much lower practical energy density compared to the theoretical value, cycling instability, and safety issues. In order to solve these problems, this project aims to develop lithium-sulfur batteries with high energy density, high cycling stability, and high safety based on porous and macroscopic CNT architectures with excellent electrical and mechanical properties and high chemical stability. This project focuses on the following aspects: development of CNT/S composite cathode with high sulfur loading and investigation of reaction kinetics; construction of CNT/Li composite anode and examination of cycling stability and safety issues; optimization of functional CNT composite interlayers and study of adsorption mechanisms with polysulfides; assembly and characterization of lithium-sulfur battery systems. The goals of this project are to achieve high performance lithium-sulfur batteries based on macroscopic CNT architectures through optimized design of CNT/S and CNT/Li composite electrodes and CNT based interlayers, to gain deep understanding to the interfacial interactions and electron transfer and ion diffusion mechanisms in lithium-sulfur systems, and to promote the developments and applications of lithium-sulfur batteries.

锂硫电池具有理论能量密度高、成本低、环境友好等优点，是最具发展前景的二次电池之一。然而由于硫和硫化锂的极低电导率，循环过程中电极体积变化引起的结构不稳定，多硫化物的溶解扩散和锂枝晶的产生，导致锂硫电池实际能量密度远低于理论值，循环寿命无法满足实用要求，并且存在安全隐患。为解决上述问题，本项目以具有优异电学、力学性能和化学稳定性的多孔碳纳米管宏观体为载体，构筑具有高能量密度并且安全稳定的锂硫电池体系。研究内容包括高载硫量碳纳米管/硫复合正极的制备和电极反应动力学研究；碳纳米管/锂金属复合负极的设计和安全稳定性研究；功能型碳纳米管基复合中间层的构筑及其与多硫化物相互作用机理研究；锂硫全电池的系统集成和性能表征。研究目标是通过碳纳米管复合电极和中间层的结构优化，获得基于碳纳米管宏观体的高性能锂硫电池体系，深入理解各界面之间相互作用、电子传输和离子扩散机理，为推动锂硫电池的发展和应用提供科学基础。

锂硫电池具有理论能量密度高、成本低、环境友好等优点，是最具发展前景的二次电池之一。然而由于硫和硫化锂的极低电导率、循环过程中电极体积变化引起的结构不稳定、以及多硫化物的溶解扩散和锂枝晶的产生，锂硫电池的实际能量密度远低于理论值，循环寿命无法满足实用要求，并且存在安全隐患。为解决上述问题，本项目以具有优异电学、力学性能和化学稳定性的多孔碳纳米管宏观体为载体，构筑具有高能量密度并且安全稳定的锂硫电池体系。本项目在以下四方面进行了深入系统的研究工作：高载硫量碳纳米管/硫复合正极的制备和电极反应动力学研究；碳纳米管/锂金属复合负极的设计和安全稳定性研究；功能型碳纳米管基复合中间层的构筑及其与多硫化物相互作用机理研究；锂硫全电池的系统集成和性能表征。利用多种形貌的碳纳米管宏观体，成功构筑出高性能锂硫电池的多种组件，并探究了其在柔性储能器件中的应用。本项目揭示了各界面之间相互作用、电子传输和离子扩散机理，推动了锂硫电池的发展和应用。本项目取得了如下代表性成果：（1）高载量碳纳米管气凝胶/硫复合电极的制备和电极反应动力学研究。（2）无定形碳修饰的碳纳米管气凝胶/锂复合电极的设计。（3）超薄碳纳米管/钛酸钡功能型中间层及其与多硫化物相互作用机理研究。（4）碳纳米管结构在锂电池中的应用及柔性锂电池的设计展望。（5）高比容量碳纳米管基柔性负极的研究。（6）高性能电解质的设计与性能研究。（7）基于双轴预拉伸的超顺排碳纳米管/活性炭超级电容器。