TiO2(B)/石墨烯界面离子液体的纳微结构及储锂机理研究

Electrochemical performances of lithium ion batteries strongly depend on the electrode materials and electrolyte. TiO2(B)/graphene composite anode material and ionic liquid electrolytes have drawn much attention in industry and academy for their outstanding properties. In this proposal, we plan to combine advanced scientific experiments (including in-situ XPS, AFM, SFG and so on) with theoretical simulation (including Density Functional Theory calculation and Molecular Dynamics method) to study the nano-microstructure, formation mechanism and stable condition of ionic liquids on the surface of TiO2(B)/graphene composite anode material, by which to establish a model of the interface between electrode material and ionic liquid electrode. By studying microstructure evolution law of ionic liquids under Charging and discharging to achieve the competition and synergistic effect of electric field, the electrostatic force between ions and cations, as well as the Van der Waals force in the interfaces. By studying the transportation and the insertion/desertion processes of lithium ions, to illustrate the synergistic effect of TiO2(B)/and graphene, thus to obtain the major factors which influence the lithium storage properties as well as its mechanism. And finally, the obtained results will provide scientific foundations for the development of high-performance lithium-ion batteries.

锂离子电池性能与电极材料的储锂性能及电解液息息相关。TiO2(B)/石墨烯复合负极材料和离子液体电解液都是当前的热点课题。本项目拟采用实验手段(原位XPS、XRD、AFM、SFG等) 并结合计算模拟(密度泛函理论和分子动力学模拟)方法，充分考虑复合电极材料的结构与组成，构建离子液体与电极材料作用的界面模型，重点考察离子液体在TiO2(B)/石墨烯电极表面的纳微结构及形成机制、稳定性条件；研究充放电条件下界面处离子液体结构的变化规律，获得离子液体阴阳离子间静电力、氢键的竞争协调机制；进一步研究充放电时锂离子的动态输运过程以及其在电极材料表面的脱嵌机制，阐明复合电极材料之间的协同作用，从而获得影响电极材料储锂性能的关键因素和储锂机理，以期为提高锂电池的电化学性能提供科学基础。

本项目采用分子动力学模拟、第一性原理计算并结合实验研究，探究了石墨烯-离子液体（ILs）等复合体系的界面结构、限域流动行为及传热性能研究，揭示了不同粘度的ILs对流动特性的影响以及纳米通道在实际运用中的设计原则，建立了调节ILs在纳米通道中流动行为的策略，预测了界面热阻的理论下限值，可用于评估纳米器件或其他储能体系等应用中的散热性能；研究了ILs -电极界面的微观结构、相互作用机制、充放电等过程及ILs双电层对超级电容器性能的影响规律，阐明了电场调控的电极界面上功能ILs的结构变化情况，揭示了ILs -电极界面纳微结构和充电过程的分子机制，发现了疏水性纳米孔可增强ILs超级电容器的电容和充电动力学性能，并拓展研究了ILs双电层对MoS2超级电容器性能的影响规律；研究了TiO2(B)、MoS2和金属氧化物等电极材料的电子结构、锂输运机理及ILs的浸润行为，阐明了TiO2(B)的电子结构及Li输运过程的微观机制，实现了兼顾平衡锚定和扩散的锂硫电池中的金属氧化物阴极材料的筛选，揭示了ILs在不同固体表面上的界面浸润行为，为基于ILs的储能器件的分子设计和调控等关键应用提供理论基础。