A new method for producing high density ACF and its application to the electrodes of EDLCs

活性炭纤维（ACF）具有比表面积大、吸附/解吸速率高的特点。然而，它的低堆积密度是其弱点之一。为了克服这一弱点，我们开发了一种生产高密度ACFs （HD-ACFs）的新方法，并研究了将HD-ACFs用作双电层电容器（EDLC）电极的可能性。我们可以通过对稳定纤维进行热压成型，然后对纤维进行炭化和活化来生产HD-ACFs。在我们的方法中，不需要任何其他过程，如粉碎或任何粘合剂。通过改变热成型过程中机械压力的负荷，可以很容易地将HD-ACF的堆积密度控制在0.2 ~ 0.86 g/cm3之间。热成型过程对后续的炭化和活化过程没有影响，因此在相同活化水平下，HD-ACF与未成型ACF的微孔结构基本相同。因此，我们可以在不失去ACF的高吸附性能的情况下生产出高容重的ACF。使用HD-ACF电极的EDLC的电容随着HD-ACF堆积密度的增加而增加，表明单个纤维被高度填充而不损失其电容。电容也随HD-ACF电极的尺寸成比例地增加。另一方面，EDLC的初始放电电流与HD-ACF电极的体积密度和尺寸几乎没有关系。这些结果表明，HD-ACF电极适合于构建高功率EDLC。

Activated carbon fiber (ACF) has high surface area and its adsorption/desorption rate is very high compared with granular activated carbons. However, its low bulk density is one of the weak points. In order to overcome this weak point, we developed a new method to produce high density ACFs (HD-ACFs) and examined the possibility for using HD-ACFs as the electrodes of the electric double layer capacitor (EDLC).We could produce HD-ACFs by the hot briquetting of stabilized fiber and subsequent carbonization and activation of the fiber. In our method, neither any other processes like crushing nor any binders are required. The bulk density of the HD-ACF could be easily controlled from 0.2 to 0.86 g/cm3 by changing the load of mechanical pressure during the hot briquetting. The hot briquetting process was found not to affect the subsequent carbonization and activation processes, so the HD-ACF has almost same micropore structure as the non formed ACF when we compare at a same activation level. Thus we could produce ACF with high bulk density without losing the high adsorption performance of ACF.The capacitance of the EDLC with the HD-ACF electrode increased with the increase of bulk density of the HD-ACF, indicating that individual fibers are highly packed without losing their capacitance. The capacitance also increased in proportion to the size of the HD-ACF electrode. On the other hand the initial discharge current of the EDLC was little dependent on either the bulk density or the size of the HD-ACF electrode. These results clarified that the HD-ACF electrode is suitable for constructing a high power EDLC.