p270

Electrochemical Formation of Porous Silicon with Medium-Sized Pores

Yukio H. OGATA,^a＊ Akihiro KOYAMA,^a Farid A. HARRAZ,^b Mohamed S. SALEM,^a and Tetsuo SAKKA^a

^a Institute of Advanced Energy, Kyoto University (Uji, Kyoto 611-0011, Japan)
^b Central Metallurgical Research and Development Institute (Helwan, Cairo 11421, Egypt)

Received October 31, 2006 ; Accepted December 13, 2006

Medium-sized pores of which diameter was over 100 nm were successfully prepared by anodization in 3 wt% HF aqueous solution containing KMnO₄ and surfactant. The presence of an appropriate oxidizing agent and a surfactant was indispensable for the formation of medium-sized pores, but the concentration dependence was not significant. Similar method was applied to the p ⁺-type silicon and led to the pore widening.

電気化学処理による水溶液電気二重層キャパシタの高容量化

下岡　俊晴^a，山崎　穣輝^a，杉本　達弥^a，定塚　哲也^a，寺石　尚央^a，長尾　恭孝^b，小田　廣和^c，松田　好�ｼ^b,d，石川　正司^a,e＊

^a 関西大学工学部応用化学科（〒564-8680　吹田市山手町3-3-35）
^b 関西大学先端科学技術推進機構（〒564-8680　吹田市山手町3-3-35）
^c 関西大学工学部化学工学科（〒564-8680　吹田市山手町3-3-35）
^d （有）研晴（〒565-0873　吹田市藤代台2-3-4）
^e 関西大学産学連携研究センター（〒564-8680　吹田市山手町3-3-35）

Capacitance Enhancement of Aqueous EDLC Systems by
Electrochemical Treatment

Toshiharu SHIMOOKA,^a Shigeaki YAMAZAKI,^a Tatsuya SUGIMOTO,^a Tetsuya JYOZUKA,^a
Hisao TERAISHI,^a Yasutaka NAGAO,^b Hirokazu ODA,^c Yoshiharu MATSUDA,^b,d
and Masashi ISHIKAWA^a,c＊

^a Department of Applied Chemistry, Faculty of Engineering, Kansai University (3-3-35 Yamate-cho, Suita 564-8680, Japan)
^b Organization for Research and Development of Innovative Science and Technology, Kansai University (3-3-35 Yamate-cho, Suita 564-8680, Japan)
^c Department of Chemical Engineering, Faculty of Engineering, Kansai University (3-3-35 Yamate-cho, Suita 564-8680, Japan)
^d Kensei Inc. (2-3-4 Fujishirodai, Suita 565-0873, Japan)
^e Research Center for Business Academia Collaboration, Kansai University (3-3-35 Yamate-cho, Suita 564-8680, Japan)

Received August 4, 2006 ; Accepted December 5, 2006

The electrochemical treatment of activated carbon electrodes has been investigated as a novel method enhancing the capacitance of electric double layer capacitor (EDLC) electrodes. The treatment at 0.7 V floating in a week at 70℃ can be applied to EDLC with aqueous electrolytes. In 30 wt% H₂SO₄ / H₂O electrolyte, the treatment causes a capacitance increase in a low voltage region: 0-0.4 V. On the other hand, in 3.5 M NaBr / H₂O electrolyte, it results in a remarkable capacitance increase of 2.4 times in a high voltage region: 0.4-1.0 V. These results suggest that the treatment mechanisms in the above electrolyte systems should be different. We report herein the origins and mechanisms of these capacitance increases.