低聚倍半硅氧烷自组装合成有序微/介孔碳及其结构调控和电容性能研究

The research focus in the field of electric double layer capacitor is to improve its energy density by regulating the pore structure of porous carbon electrode materials. Ultramicroporous carbons with the pore diameter close to the ion size in electrolytes have excellent specific energy, but their rate capability under a high charge/discharge current condition is quite moderate due to the absence of mesopores or macropores as a smooth charge-transfer pathway for the ions. This project will employ the oligosilsesquioxanes with intramolecular organic/inorganic hybrid structure as both the carbon sources and self-template for the production of micropores. Ordered mesostructured precursors will be first prepared via the hydrogen-bonding self-assembly of oligosilsesquioxanes and block copolymer surfactants. After the carbonization of the precursors and the following etching of silica constituent, the hierarchical ordered mesoporous carbon electrode materials with micropores inside the mesopore walls will be obtained. It will be investigated about the self-asembly behavior and mechanism of oligosilsesquioxanes/block copolymers system, as well as the influence of the oligosilsesquioxanes with the different polymerization degree (molecule size) on the micropore size. Based on the above research, it will be feasible to regulate both the microporous and mesoporous structures of hierarchical porous carbon electrode materials. Furhermore, this project will explore the relationship between the structrual parameters and electrochemical performance of the ordered hierarchical porous carbons, and establish the theoretical foundation for the design and preparation of the porous carbons used as the capacitor electrode materials with both high energy density and high power density.

通过调控多孔碳电极材料的孔隙结构来提高双电层电容器的能量密度是该领域的研究重点。孔径与电解液离子尺寸相当的超微孔碳拥有大比容量储能特性，但介/大孔尺度的离子传输通道的缺乏影响其大倍率充放电性能。本项目拟采用具有分子内有机/无机杂化结构特点的低聚倍半硅烷作为碳源和产生微孔的自模板剂，并通过该物质与嵌段共聚物表面活性剂之间氢键自组装构筑有序微孔/介孔碳前驱体，经碳化并蚀除硅氧组分后，制备介孔孔壁上拥有超微孔结构的有序分级孔碳电极材料。研究探讨嵌段共聚物/低聚倍半硅氧烷体系的自组装特性，以及不同聚合度（分子尺寸）的低聚倍半硅氧烷对微孔孔径的影响规律，为实现微孔和介孔结构同时可调的分级孔碳电极材料的制备提供依据；探讨有序分级孔结构碳材料的结构参数与电化学性能的本质联系，从而为设计制备高能量密度和高功率密度的电容器多孔碳电极材料提供理论基础。

在保持碳基双电层电容器高比功率的前提下，通过调控多孔碳电极材料的孔隙结构来提高其能量密度是该领域的研究重点。孔径与电解液离子尺寸相当的超微孔碳具有大比容量特性，但介/大孔尺寸的离子通道的缺乏影响其倍率性能。本项目提出采用低聚倍半硅氧烷作为碳源和产生微孔的自模板，两亲性嵌段共聚物作为介孔模板，通过两者之间的氢键自组装制备有序微孔/介孔多级孔碳电极材料。主要研究内容和取得的重要结论如下：（1）以不同聚合度的笼型低聚倍半硅氧烷为前驱体制备不同孔径的微孔碳材料，研究表明聚合度与孔径具有正相关性，说明可利用前驱体中无机硅氧笼的印迹作用精确控制碳产物的微孔尺寸；（2）发现含胺基的笼型倍半硅氧烷能够与多种含聚氧乙烯嵌段的两亲性嵌段共聚物进行自组装形成有序介观结构，选用不同分子结构的嵌段共聚物可获得不同介观对称性的碳产物，如二维六方、三维体心立方和三维面心立方结构，而且，改变嵌段共聚物的分子量可对碳材料的介孔尺寸进行调控；（3）以上述多孔碳电极材料为基础，研究其孔隙结构对双电层电容性能的影响，发现以笼型八聚倍半硅氧烷为前驱体制备的微孔碳具有更大的比电容，且在微孔碳中引入介孔难以提高其比容量，但可显著改善其倍率性能，且介孔孔径越大，倍率性能越好。本项目的研究成果同时会为新型自组装体系、有机/无机杂化多孔材料提供新方法和新的研究体系，并为高性能储能材料的开发提供一定的技术支撑。