离子液体@MOF材料的构筑及其质子导电性能的理论模拟与实验研究

This project will focus on extending the temperature range of the proton exchange membrane (PEM) in a fuel cell (FC). Ionic liquids, with an anhydrous proton conducting effect, are combined with Metal-Organic Frameworks (MOFs) to prepare ionic liquid @ MOF materials. The framework of MOFs has support roles and high stabilities, which is conducive to fix / stabilize ionic liquids and improve the high - temperature proton conductivity of materials. Meanwhile, the microporous effects of MOFs can reduce the viscosities and melting points of ionic liquids, stabilize the low-temperature performances of materials, thus, extend the temperature ranges of proton conductivity and obtain the anhydrous proton conductive PEM fillers with stable performances in a wide temperature range. In this project, first, the molecular simulation method will be used to do the matching study on the structures of ionic liquids and the pore effects of MOFs and explore the mechanisms of proton transfer and the structure-function relationships and rules. Then, by applying the rules above, MOFs will be modified to match the structural characteristics of ionic liquids via hierarchical pore MOF synthesis and MOF modification,.regulating the pore sizes and the chemical environment in holes, etc. Ionic liquid @ MOF materials will be prepared and the preparation methods of composite materials will be optimized by combining the performance studies. Finally, a new kind of ionic liquid @ MOF proton conducting materials with a large operating temperature range will be obtained. It is expected that the successful implementation of this project will help to improve the adaptability to ambient temperature of PEM, and promote the application and popularization of PEMFC.

本项目着眼于扩展燃料电池(FC)中质子交换膜(PEM)的温度适用范围。离子液体具有无水质子导电作用，结合MOF骨架的支撑作用与高稳定性，制备离子液体@MOF材料，有利于固定离子液体并提高材料的高温导电性能；同时，MOF材料的微孔效应可以降低离子液体的黏度和熔点，稳定材料的低温性能，从而扩展材料的工作温度区间，获得宽温度范围内性能稳定的无水质子导电PEM填充材料。首先，通过分子模拟方法，进行离子液体结构与MOF孔效应的匹配性研究，探索质子传递的机理及构效关系与规律。然后，运用以上规律设计材料，经多级孔MOF合成及MOF修饰，调控孔尺寸、孔内部化学环境等，匹配离子液体的结构特征，制备离子液体@MOF材料。结合性能研究，优化复合材料的制备方法。最终，获得具有较大工作温度区间的新型离子液体@MOF质子导电材料。本项目的成功实施，将有助于提升PEM对环境温度的适应性，推动PEMFC的应用和普及。

燃料电池汽车以高效率和近零排放被普遍认为是解决环境和能源问题的动力源之一。作为世界上最成熟的绿色能源技术之一，质子交换膜燃料电池(PEMFC)具有重要的影响力。其关键导电组件质子交换材料目前存在性能可适温度区间较窄，湿度依赖度大等问题。本项目结合离子液体的高温无水质子传递作用和MOF材料的骨架支撑作用和微孔效应，进行离子液体@MOF材料的结构匹配、实验制备与质子传递性能探索，构建宽温度范围内可用的高性能质子交换材料。项目执行期间，首先，建立一种可推广的MOF材料质子导电性精微调控方法；其次，建立了离子液体@MOF材料的简易可实现制备方法；最终成功制备MOF材料20余种，离子液体@MOF材料40余种，MOF及离子液体@MOF膜材料约20种，并对以上材料进行了结构和性能表征。按计划拓展了质子导电MOF材料从低温263 K到高温423 K及相对低湿度下的质子导电性研究，不完全统计获得目标超质子导电材料14种，涵盖高温423 K，中温368 K，353 K，303 K，低温268 K，263 K等。部分材料名称和电导率如下：423 K，MIM-CF3SO3@LP-HKUST-1-100％ (2.31 × 10-4 S·cm-1)；368K，MIM-CF3SO3@MOF-801-125% (1.73 S∙cm-1)；353 K，MIM-CF3SO3@LP-HKUST-1-100% (1.79 × 10-1 S·cm-1)，CS/CMMIM@MIL-88A-25% (1.33 S∙cm-1)，CS/CMMIM@MIL-88B-125% (1.42 S∙cm-1)；303 K，CS/ML-UiO-66-(NH2)(SO3H)-15% (8.8 ×10-2 S∙cm-1)；268 K，MIM-CF3SO3@MOF-801-125% (1.79 ×10-2 S∙cm-1)；263 K，CS/CMMIM@MIL-53(Fe)-75% (2.1 × 10-3 S∙cm-1)，CS/CMMIM@MIL-88B-125% (1.28 × 10-3 S∙cm-1)等。以上材料的质子电导率在中温高达1.73 S∙cm-1和1.33 S∙cm-1，263 K质子电导率达10-3数量级，268 K达10-2数量级，为MOF材料在PEMFC中的实际应用提供了理论和实验基础，具有重要的现实意义。