导电聚合物-金属有机框架复合储能材料的设计、制备与应用

Metal-organic frameworks (MOFs) materials have invoked compounding attentions and indicated outstanding potential advantages in energy storage applications, due to their controllable pores, enormously high surface areas and abundant active metal sites. Regrettably, due to the little conductivity, most of MOFs show the low capacitance, whose utilizations in supercapacitors are limited to precursors or templates for carbons or metal oxides. New-type MOFs with good electrical conductivity are attractive and can achieve the high capacitance, but this approach has the limitations of production cost, synthesis time, and universality for producing new MOFs. Thus, hybridizing the existing MOFs with other conducting materials is an effective and simple strategy to endow MOFs with good conductivity. For previous MOFs-based hybrids, superiority of porosity and high surface areas of MOFs are partly sacrificed, or the electron transport paths constructed by conducting materials often show low efficiency. In this proposal, MOFs will be hybridized with conducting polymers at the strategy of two core/shell nanostructures: conducting polymers (nanowires array) as core/MOFs (film) as shell, and MOFs (particles or nanowires) as core/conducting polymers (porous film) as shell. In this strategy, more complete electron transport paths among MOFs as well as MOFs and electrode substrates will be constructed; meanwhile, advantages of porosity and high surface areas of MOFs will also be fully utilized. The resultant conducting polymer-MOFs hybrids will possess good electrical conductivity and effective porosity with high-performance capacitive property for supercapacitors. This strategy may shed some valuable and novel methods, ideas, or breakthroughs for design and preparation of MOFs-based hybrids for energy storage application.

金属有机框架(MOFs)材料孔道结构丰富、比表面积高、金属活性位点丰富，是极具发展潜力的下一代储能材料，但绝大多数MOFs的导电性较差，导致低电容容量，少数导电MOFs受限于种类、制备条件及产率、开发成本等诸多方面，故复合现有MOFs与其他导电材料是赋予MOFs高导电性的一条有效策略。先前研究中的复合材料，存在牺牲MOFs多孔、高比表面积的部分优势或导电材料构建的电子传输通路低效等缺点。本项目拟采用导电聚合物与MOFs复合，以导电聚合物(纳米线阵列)为核/MOFs(膜层)为壳、MOFs(粒子或纳米线)为核/导电聚合物(多孔膜层)为壳的两种核/壳纳米结构的思路，在MOFs之间以及MOFs与电极基底构建更加完善电子传递通道，同时充分利用MOFs多孔、高比表面积的优势，制备电容性能优异的导电聚合物-MOFs复合纳米储能材料，为基于MOFs的新型储能复合材料的设计与制备提供新方法、新思路、新突破。

柔性超级电容器具有较高的功率密度、较长的循环寿命、较好的机械柔性及较低的成本等优势，是可穿戴智能电子设备的理想供电装置。金属有机框架（MOFs）由于其优异的特性（多孔结构、比表面积大、丰富的活性位点、结构易调整等）而成为柔性可穿戴式超级电容器的新型电极材料。但大多数MOFs的固有导电性较差，导致低电容容量；少数高电导率的MOFs在种类、制备条件、产率及开发成本等方面也有所限制；将MOFs作为牺牲模板制备多孔碳或金属氧化物等电极材料容易造成结构坍塌导致比表面积降低。为解决这些瓶颈，MOFs与其他导电材料的复合是在不牺牲MOFs多孔、高比表面积优势的条件下，构建高效电子传输通道，赋予MOFs高导电性、提高电容性能的一条有效策略。按照这一思路，本项目利用聚吡咯（PPy）为导电媒介，复合PPy和MOFs，分别构建了PPy薄膜/MOFs纳米线和多孔PPy/MOFs纳米线（或纳米颗粒）的纳米结构柔性电极材料。具体地，本项目分别设计并制备了聚吡咯薄膜/Cu-CAT MOF纳米线阵列复合膜电极、聚氨酯海绵/聚吡咯/Cu-CAT MOF纳米线阵列复合海绵电极、多孔聚吡咯负载Cu-CAT MOF复合电极材料、以及聚吡咯空心骨架泡沫负载Ni-CAT MOF纳米线柔性电极，建立和掌握了一套完善的高性能电化学储能的多孔结构聚吡咯-纳米结构MOFs复合材料的合成方法和工艺，及其结构、组分调控方法。优选所制备的导电聚合物-MOFs复合材料，组装了全固态柔性超级电容器，表现出优异的电化学储能性能、长的循环充放电寿命、强的耐温性、高的机械柔性和宽的工作温度范围，具备可穿戴设备应用潜力。本项目研究成果探索推动了基于MOFs复合材料应用于超级电容储能的普遍性、实用性和规模化。