新型功能化锂硫电池隔膜增强储能的力-化耦合机理研究

锂硫电池充放电过程中多硫化锂的“穿梭效应”问题严重限制其商业化前景。通过纳米复合材料修饰商业隔膜是解决该问题的重要方法，功能化隔膜的界面结合性能优化及其电传导、多硫化锂吸附/催化-转化三大功能协同增强储能已成为科研工作者亟待解决的关键科学问题。本项目利用零维量子点耦合氮掺杂二维碳复合修饰层中各组分优势和特有的异质结效应，提升功能化隔膜的界面稳定性及吸附/催化-转化多硫化锂的效率。采用鼓包法对新型功能化隔膜不同力-化耦合下界面结合性能进行动态表征，明晰界面结合性质对“穿梭效应”及锂硫电池性能的影响规律。利用原位电化学/拉曼光谱结合第一性原理计算研究新型功能化隔膜与多硫化锂的相互作用，揭示三大功能协同增强多硫化锂吸附/催化-转化的动力学机制。建立功能化隔膜提升锂硫电池整体性能的力学与电化学的内在关联与分析方法，阐明增强储能机制和途径，为高性能锂硫电池的研发提供科学指导和技术支撑。

The commercial development of high energy-density lithium-sulfur batteries is seriously hindered by notorious “shuttle effect” of lithium polysulfides during electrochemical reaction process. It is revealed that the problem can be effectively solved using novel functionalized separator of lithium-sulfur batteries via the modification of nanocomposite. It is highly important, but challenging to design and fabricate novel functionalized separators with excellent interfacial bonding properties and synergistically enhanced three functions of adsorption and catalytic conversion of lithium polysulfide as well as electron conductivity. In this project, we will take advantages of quantum dots with outstanding adsorption/catalytic activity and nitrogen-doped two-dimensional carbon with high conductivity as well as unique heterogeneous interfacial effect among them, thereby constructing novel functionalized separators with excellent interfacial bonding properties and synergistically enhanced three functions. We will investigate interfacial bonding properties under different chemo-mechanical coupling by using bulge observation technology to reveal their influence on the electrochemical performance of the lithium-sulfur batteries. Meanwhile, we will study the interaction between the functionalized separators and lithium polysulfides using the combination techniques of in situ electrochemical/Raman spectroscopy and first-principles calculations, thereby revealing the underlying mechanism for synergistic enhancement of adsorption and catalytic conversion of lithium polysulfide as well as electron conductivity to depress the “shuttle effect”. The intrinsic correlation model of chemo-mechanical coupling as well as analytical method will be established to explain the enhanced performance of lithium-sulfur batteries via novel functionalized separators. Our research is expected to provide scientific and technical guidelines for the development of high-performance lithium-sulfur batteries.