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

点击翻译按钮获取中文摘要

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.