溶膠-凝膠法製備官能基化二氧化矽/Nafion®複合膜材用於甲醇燃料電池之性質研究

Properties of Sol-Gel Derived Functional Silica / Nafion® Composite Membrane for Direct Methanol Fuel Cell

李佳勳(Chia-Hsun Lee)

指導教授 ： 馬振基

國立清華大學/工學院/化學工程學系/碩士(2007年)

摘要

本研究藉由3-aminopropyl-trimethoxysilane (NH2-silane)、Trimethoxy(propyl)silane (R-silane)及(3-Mercaptopropyl)trimethoxy-silane (SH-silane)與Nafion®進行sol-gel反應製成Nafion®/官能基化二氧化矽複合膜材，探討帶有不同官能基化的二氧化矽，對膜材的性質之影響。其中Nafion®/silica-SO3H複合膜材是經由Nafion®/silica-SH複合膜材使用10 wt %雙氧水氧化所得到，最佳的氧化條件為在60℃反應一小時。藉由FT-IR、XPS、29Si-NMR、DSC及 SEM等儀器來做膜材的物理及化學性質測試及分析。
　　Nafion®/官能基化二氧化矽複合膜材之性能可藉由甲醇滲透率、質子導電度及電池測試而得知。Nafion®/silica-SO3H膜材由於有較多的磺酸根，因此在質子導電度方面高於Nafion®，含有0.6 wt %二氧化矽的Nafion®/silica-SO3H複合膜材，其質子導電度為0.1338 S/cm，高於Nafion®的0.1256 S/cm。Nafion®/silica-NH2膜材由於酸鹼作用力的產生，在甲醇滲透率方面低於Nafion®，含有0.6 wt %二氧化矽的Nafion®/silica-NH2複合膜材，其甲醇滲透率為3.99*10-6 cm2/s，低於Nafion®的5.51*10-6 cm2/s。
　　對於含有0.6 wt %二氧化矽的Nafion®/silica-SO3H 及Nafion®/silica-NH2複合膜材之電池性能測試，此膜材電池性能表現皆優於商用的Nafion®膜材，顯示出的高導電度以及低甲醇滲透率，對於電池性能的提升有所助益。電流密度於0.2伏特時，Nafion®/silica-SO3H 、Nafion®/silica-NH2複合膜材及Nafion®分別為70、72.5 與 62.5 mA cm-2；最大電池功率分別為15.18、16.05 及13.04 mW cm2，因此，增加複合膜材質子導電度以及降低甲醇滲透率會使膜材更適用於直接甲醇燃料電池中。

關鍵字

燃料電池 ； 質子交換膜 ； 聚四氟乙烯 ； 直接甲醇燃料電池

並列摘要

Nafion®/functionalied silica composite membranes have been prepared using 3-aminopropyl-trimethoxysilane (NH2-silane)、Trimethoxy(propyl)silane (R-silane)、(3-Mercaptopropyl)trimethoxy-silane (SH-silane) via hydrolysis sol-gel reaction then followed by solution casting. Nafion®/sulfonated silica composite membranes were prepared using Nafion®/silica-SH composite membranes oxidiated by 10 wt% H2O2 solution. The results indicated that the optimum oxidiation condition was at 60℃ within 1 hr. Physical and chemical properties of the composite membranes were characterized by FT-IR, XPS, 29Si-NMR, DSC and SEM.
　　The performance of the Nafion®/functional silica composite membranes was evaluated in terms of methanol permeability, proton conductivity and cell performance. The Nafion®/0.6 wt% silica–SO3H composite membranes possess a higher conductivity (0.1338 S/cm) than that of pristine Nafion® (0.1256 S/cm). The Nafion®/0.6 wt% silica–NH2 composite membranes showed a lower methanol permeability (3.99*10-6 cm2/s) than that of pristine Nafion® (5.51*10-6 cm2/s). The current densities were measured as 70、72.5 and 62.5 mA cm-2 at a potential of 0.2 V for Nafion®/0.6 wt% silica–SO3H、Nafion®/0.6 wt% silica–NH2 and pristine Nafion®, respectively. The maximum power density was 15.18、16.05 and 13.04 mW cm2, respectively. Composite membranes containing 0.6 wt% silica–SO3H or 0.6 wt% silica–NH2 possess high proton conductivity and low methanol permeability will be suitable for DMFC application.

並列關鍵字

fuel cell ； proton exchange membrane ； Nafion ； DMFC

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