Preparation And Application Of Aligned Carbon Membrane Induced By Directional Freezing Of SPEEK-PVA

Directional freezing is a newly developing method for preparing aligned material. It has attracted great interests due to simple operation and without any chemical reaction involved. Herein, directional freezing was employed to prepare aligned carbon membrane, which made the pore channels size of carbon membrane to be controllable.In this work, the aligned carbon membrane was prepared by a mixture of sulfonated poly(ether ether ketone)(SPEEK) and polyvinylaclcohol (PVA) as precursor, and water was used as solvent. Detailed preparation processes and effect factors such as precursor types, precursor composition and freezing temperature were investigated systematically. In the different polymer matrix, the interaction between ice crystals formed by solvent and polymer chains was also different, leading to the change of channels structure in the membrane. While increasing the concentration of SPEEK or PVA, the pore size of membrane will decrease. This result is attributed to the limit of ice crystal growth which causes a small size. Similar phenomenon exhibited when the molecular weight of PVA was changed. That will take effects on the structure of pore channels in the membrane. In addition, the effects caused by CNTs addition were also investigated. The presence of the CNTs changed the atmosphere where ice crystals were formed and contributed to the formation resistance of ice crystals, which contributed to form tiny ice crystals. Additionally, when the freezing temperature decreased, the formation of ice crystals became faster, hence the aligned pore channel size of the carbon membrane decreased.The obtained aligned carbon membrane from directional freezing of SPEEK and PVA was used as electrode of supercapacitor to test the capacitor performance. It’s found that the aligned carbon membrane from SPEEK and PVA had capacitance characteristics, but not very outstanding, only0.22F/g. Then the membrane was activated in carbon dioxide atmosphere for0.5h, the capacitance was increased to13.53F/g, and activation in carbon dioxide can significantly improve the capacitance characteristics of aligned carbon membrane from directional freezing of SPEEK and PVA. This study shows that aligned carbon membrane induced by directional freezing of SPEEK-PVA has good potential application as electrode of supercapacitor.