木质基柔性多孔电极材料的微观特性及储能机理研究

Wood transverse section slice(WTSS) has the characteristics of flexible, porous and hydrophilic instinctively. In this proposal, we use natural WTSS as substrate, polypyrrole(PPy), grapheme(GE) and PPy/GE as active materials, to make a new, wood-based flexible porous electrode with large surface areas and excellent conductivity. Methods of FTIR, XRD, XPS, RS, SEM, nitrogen-absorption are used to estimate the chemical construction, microstructure, specific surface area and pore size distribution of wood based electrode. The active material species and adhesion method have regulatory effect on microstructure, microscale and morphology of wood based electrode, which needs to analyze deeply. The action mechanism of porous skeleton structure of WTSS on electrolyte reservoir and mechanical buffer of wood-based supercapacitor are in-depth discussed by comparing microscopic characteristics of electrode based on transverse section and tangential section wood slice. The electrochemical properties of capacity, power density and cycle life of wood-based supercapacitors are studied by electrochemical workstation. The charge storage mechanism and characteristics of wood-based electrode are illuminated in this project. The structure-activity relationship between the microporous structure of wood-based electrode and electrochemical performance of wood-based supercapacitors are also explored. This project is a product of interdisciplinary, and provides a new way to wood functionalization and new green energy storage materials.

本研究首次以横切面薄木切片为基体，利用其自身的柔性、多孔及亲水特性，将活性物质聚吡咯、石墨烯、聚吡咯/石墨烯附着在薄木切片的微孔表面，得到比表面积高、导电性好的新型木质基柔性多孔电极材料。利用FTIR、XRD、XPS、RS、SEM、氮吸附等方法对电极材料的化学结构、微观结构、比表面积及孔径分布进行评价，进一步分析活性物质种类和附着方法对电极材料微观结构、微孔尺度、微观形貌的调控作用。通过与弦切面木质基电极材料的微观特性比较，深入探讨横切面薄木切片的多孔骨架构造对电极材料的电解液存储、应力缓冲的作用机理。利用电化学工作站对木质基电极材料组装的木质基超级电容器的比容量、功率密度、循环寿命等电化学性能进行研究，阐明木质基电极材料的储电特性和电荷储存机理，揭示木质基电极材料微孔结构与木质基超级电容器电化学性能之间的构效关系。本项目是多学科交叉产物，能够为木材功能化和新型绿色储能材料探索一种新途径。

赋予传统木材新功能是木质功能材料研究和发展的方向。利用木材作为骨架或载体来制备先进功能材料需要新的理念和设计方法，既能保持和充分利用木材自身的结构和天然性质，又能在木材的细胞腔内部引入新的功能特性，是开发基于天然木材的新型人工复合材料的热点研究方向。基于这一思路，本项目利用木材的多孔特性、亲水性以及优良机械性能，将微米级厚度的薄木作为支撑材料和载体材料，与导电高分子和纳米碳材料复合，获得成本低廉、环境友好、超薄、柔性、轻质的木质基复合电极材料及其全固态柔性超级电容器器件。因此，本项目主要研究内容和重要成果如下：.1. 利用原位聚合和表面沉积法成功将PPy、RGO及PPy/RGO负载到薄木骨架上得到三种微观结构可控和导电性能优良的柔性薄木电极材料，并成功组装成电化学性能良好的全固体柔性电容超级电容器器件。.2. 获得了三种薄木电极材料的微观、化学、机械等结构与性能特征参数，得出了薄木表面活性物质负载量对薄木电极微观结构与电导性能影响规律，阐述了活性物质与薄木间的附着机理和界面结合机制（木材工业, 2016; 林业科学, 2017）。.3. 阐述了薄木作为电解液天然存储仓库的机制，揭示了薄木多孔结构和亲液特性对超级电容器离子扩散、电子转移、电荷传输的性能影响规律，获得了薄木电极及其全固态超级电容器的电化学特性及储能机理（RSC Advances, 2015; Electronic Materials Letters, 2015; RSC Advances, 2017）。.本项目研究成果对于深层次开发木质功能新材料，拓展传统木材学科发展，探索新型绿色储能材料，具有重要意义。