Surface modification of activated carbon cloth and its application for the electrode of capacitor

为了获得大容量、高功率，作为双电层电容器电极的活性炭布(简称ACC)应具有较大的比表面积。然而，表面上的表面功能物种可能会导致电容的降低和内阻的增加。因此，ACC的表面官能团应该较少。它们通常是含氧的表面官能团，表现出酸性。用有机分析方法对它们进行了表征，但它们的结构非常复杂。用气相色谱-质谱仪和红外漫反射光谱可以直接检测其表面物种。刘易斯基材吸附在表面物种上。研究了表面物种与吸附基材之间的相互作用。以碳化布为原料，在水蒸气中加热，研究了碳化布的比表面积变化和气孔形成机理。在600℃以上，比表面积和孔径分布发生了显著变化。研究了表面物种的变化。我们发现，在水蒸气中处理存在两个过程，一个是表面物种的分解过程，表面没有发生变化；另一个是表面发生变化的活化过程。红外光谱结果表明，吸附基材对表面物种有一定的影响，而伏安法测定结果表明，吸附对电极容量影响不大。在激活过程中，ACC的处理能力逐渐增强。这表明，表面积对ACC的容量有很大影响。我们正在研究活化过程对容量的影响。

In order to obtain high capacity and high power, the activated carbon cloth (denoted as ACC) as the electrode of electric double layer capacitor should have large surface area. However, the surface functional species on the surface may cause the decrease in capasity and the increase in internal resistivity. Therefore, ACC should have less surface functional species. They are usually the surface functional species with oxygens and show acidic property. They were characterized by organic analysis method, but they were very complicated. We could directly check the surface species by GC-MASS and IR diffuce reflectance spectroscopy. Lewis base materials were adsorbed on the surface species. The interaction between the surface species and the adsorbed base materials was studied. Carbonized cloth, which was a starting material, was heated in water vapor to stydy the change in surface area and the formation mechanism of pore. The surface area and pore size distribution changed dramaticallyabove 600℃. The change of surface species was studied. We found that by the treatment in water vapor two processes existed.One was the decomposition process of surface species without no surface change, and the other, the activation process with the change in surface area. The surface species were effected by adsorption of base materials according to IR result, but the capacity was not affected largely according to voltammetry. The capacity of ACC treated during activation process gradually increased. This suggests that the surface area effected largely on the capacity of ACC. We are studing the effect of activation process on the capacity.