基于煤族组分分离并行发泡的薄膜泡沫炭制备与层次孔调制及用于超级电容器的基础研究

It is well known that electrode materials play a decisive role on electrochemical performance of supercapacitors, and the carbon-based electrode materials are the most studied, also the most widely used. However, regardless of activated carbon, carbon nanotubes, carbon fibers, aerogels or grapheme, each kind of electrode material has its advantages as well as the corresponding fundamental problems, such as small specific surface area, low utilization rate, easy to agglomerate and stack, high cost, complex processing technology and difficult to mass production. Applicants have creatively developed a new method previously to prepared carbon foams with three dimensional network and thin film structure using coal as raw material. The loose medium component of coal foam during the process of separation. Making use of the peculiar property, the carbon foams made from loose medium component have ultrathin and homogeneous pore walls which is very favorable to modulate hierarchical pore on carbon foams by further hierarchical activation. The hierarchical porous carbon prepared can meet high porosity, highly active specific surface area and fast electron/ion transmission path that the ideal carbon-based electrode materials need. The advantages of the method are low cost, simple process and the raw materials easy to get. This research project takes advantage of this idea to prepare carbon-based electrode material supercapacitor with excellent electrochemical performance and focuses on preparation mechanism of thin film carbon foams, modulation of hierarchical pore structure and effect of pore structure on electrochemical performance. To make an important contribution to new development of coal-based electrode materials.

众所周知，电极材料对超级电容器电化学性能起着决定性作用，而碳质电极材料目前研究最多，应用也最广。然而，不论是活性炭、碳纳米管、炭纤维、炭气凝胶还是石墨烯，在各具优点的同时也存在着相应的根本性问题，比如要么比表面积小或利用率低，要么易团聚和堆叠，要么成本高工艺复杂难以宏量制备。申请者前期创造性地发明了一种以煤为原料制备具有三维网状薄膜结构泡沫炭的新方法，借用了煤中疏中质组族组分在分离的同时并行发泡的独特特性，所制泡沫炭泡壁超薄且光滑均一，非常有利于通过分级活化法调制出层次孔分布，进而获得碳电极材料所需要的多孔性、高活性比表面积和快速电子/离子传输路径。该方法原料易得，工艺简单，成本低廉。本项目研究即是利用这一思路，通过煤中疏中质组族组分制备出性能优良的超级电容器电极用碳质材料，重点研究该过程中薄膜泡沫炭生成、层次孔结构调制及孔结构对电化学性能影响等机理，为煤基电极材料的新发展做出重要贡献。

电极材料对超级电容器电化学性能起着决定性作用，而碳质电极材料目前研究最多，应用也最广。煤炭是自然界中储量最丰富的碳源，但煤炭组成复杂，不同组分性质差异大。本项目采用前期发明的煤全组分族分离的方法，将煤中具有不同显著特点的疏中质组、密中质组和重质组族组分首先分离出来，然后再依据其特殊性质，设计不同的工艺路线和方法制备具有多孔性、高活性比表面积和快速电子/离子传输路径的优良碳质电极材料。这些方法主要包括：以疏中质组为原料制备光滑无缺陷三维网状薄膜结构泡沫炭，再通过KCl辅助KOH共同活化造孔和调制孔结构；直接以疏中质组为原料，并分别采用ZnCl2为一次活化剂KOH为二次活化剂的二次活化法、以纳米MgO为模板剂的模板法、以三聚氰胺为助剂的共炭化-活化法、以KH2PO4为辅助剂的一步法以及木质素协同疏中质组的水热-炭化法等制备层次孔炭及微孔结构多孔炭；以密中质组为原料、纳米ZnO作模板剂的一步法制备多孔炭；以重质组为原料，经浓盐酸、浓硝酸和丙酮溶液预处理制备富含氧官能团的花瓣状结构多孔炭；以重质组和密中质组为原料，重组族组分共活化并自模板制备分级多孔炭等。所制备的多孔炭材料电化学性能良好，如比表面积可达3347.15 m2/g、在10 A/g的电流密度下比电容达262 F/g、倍率性能达72%的较理想的超级电容器电极材料等。研究还对煤中各族组分进行了详细的组成结构解析，建立并全面阐述了煤嵌布结构模型新理论，探讨了疏中质组族组分分离并行发泡机理、精制方法及与薄膜泡沫炭结构和性能关系，介微孔孔径分布类型与多孔炭电化学性能联系及其机理等。项目所形成的成果具有原料易得、工艺方法简单、成本低廉等特点，为超级电容器用碳质材料的工业化生产提供了机会，为煤炭非燃料利用提供了新的思路，所构建的煤嵌布结构模型理论对指导煤炭高值化利用具有重要理论意义。