基于导电金属有机骨架材料和离子液体的固液界面储能机理的研究

As an advanced class of electrical energy storage devices, supercapacitors, also called electrical double layer capacitors (EDLCs), are being of importance to energy storage community. Aiming at addressing the key issue of supercapacitor development (i.e., to enhance the energy density), the research proposed in this project will take the conductive metal-organic frameworks (MOFs), possessing high surface area, as the electrode and the ionic liquids, enduring high work voltage, as the electrolytes. The first principle calculation and molecular dynamics simulation combined with electrochemical measurements will be taken as the major approach to investigating the solid-liquid interfaces, storing the electrical energy, formed by conductive MOFs and ionic liquids. Different voltages and temperatures will be chosen to explore the effects of characteristic parameters of conductive MOFs and ionic liquids on the distribution and transport of components and the capacitive feature of the electrode-electrolyte interfaces as well as the underlying fundamentals. The results would be of great significance to possibly, in a molecular level, reveal the energy storage mechanism in supercapacitor, which would pave a way for the design and manufacture of supercapacitors with both higher energy and power densities. The distinguishing feature in this research is that based on the comparison of simulations and experiments, the model would be built to bridge the correlation among the characteristic parameters of conductive MOFs and ionic liquids, properties of solid-liquid interfaces, and the capacitive performance and then to uncover new storage mechanism in porous supercapacitor in a deeper level. The innovation in this work is to develop the constant potential method to mimic the voltage applied on arbitrary electrode surface to model the MOFs-based supercapacitor under different applied voltages and temperatures. The quantitative comparison may be achieved, due to the unique feature of MOFs, that is, possessing periodic network-like crystalline properties.

作为一种先进的绿色电能储能装置，超级电容器在储能领域中正占有着越来越重要的地位。为解决超级电容器能量密度低这一核心问题，本项目拟采用比表面积大的多孔导电金属有机骨架材料（MOFs）为电极、工作电压高的离子液体为电解质，结合第一性原理计算、分子动力学模拟和实验测量方法，以导电MOFs和离子液体形成的固液储能界面为研究对象，探究不同电压和温度下，MOFs和离子液体的特征参数对固液界面的组分与浓度分布/输运和电容特性的影响及其作用机制，以期从分子层面揭示超级电容器的储能机理，来指导设计并制备出具有更高能量密度的超级电容器。特点在于通过对比分析模拟和实验结果，建立导电MOFs/离子液体特征参数、固液界面性质和电容特性之间的关联模型，发现新的多孔电极超级电容器的储能机理。创新在于开发直接在电极上施加电压的模拟技术，根据MOFs具有周期性网络结构的特性，对其进行分子模拟，有望实现模拟和实验结果的定量比较。

实现我国“碳达峰、碳中和”目标，先进的储能技术必不可少。作为一种新型的绿色储能装置，超级电容器具有功率密度高、充放电快、循环寿命长等优点，已成为全球储能领域内的研究热点与前沿。在保有其高功率密度的前提下，如何提高能量密度是超级电容器领域内的核心难题之一。.鉴于此，本项目立足工程热物理与电化学以及计算机等学科的交叉融合，以离子液体为电解液、纳米多孔材料（主要有导电MOFs）为电极，开发先进的分子模拟方法与技术，从微观界面传质与能量传递的角度出发，通过研究离子液体与多孔电极形成的微纳双电层固液界面，结合实验合成、表征与测量，从分子层面揭示了超级电容器的储能机理——阐明了离子液体和多孔电极如影响双电层固液界面结构与形成过程以及器件储能性能——最终开发出了高性能超级电容器。项目取得了一系列创新成果，推动了超级电容器基础理论的发展和储能技术的研发：.1）建立了准确高效刻画固液界面的等电势分子模拟方法与技术.提出了在等电势下调控输入电压和电流的模拟新方法，开发了具有独立知识产权的模拟软件，不但能准确描述超级电容器固液界面微观结构与形成过程，而且适用于任意形貌结构的电极；被Nature Communications期刊论文评价为“首个分子动力学模拟”。.2）提出了精准调控界面微观结构以提工作电压的机制与策略.阐明了界面离子液体的微观结构及其形成规律，建立了调控含水离子液体界面结构的有效策略，提高了超级电容器工作电压与能量密度；被爱沙尼亚科学院Enn Lust院士评价为“令人感兴趣”。.3）构建了兼具高能量密度和功率密度的超级电容器新体系.揭示了孔径为离子直径半整数倍的纳米孔能加快充电的新规律与作用机理，提出了导电MOFs-离子液体超级电容器新体系，实现了能量和功率密度的同时提升；被德国国家工程院Xinliang Feng院士评价为“本质性指导”、Nature Communications期刊论文评价为“开创性工作”。.依托该项目，已毕业博士生4人、硕士生8人；发表第一或通讯作者SCI论文15篇（Nature子刊3篇ESI高被引2篇），获批发明专利4项、软件著作权2项。项目负责人受邀做国际学术报告6次（任分会主席5次）、全国会议报告4次，任Energy Advances副主编，入选英国皇家化学学会Fellow、获湖北省杰出青年基金和2022年度湖北省自然科学一等奖（排名第一）。