磺酸化高分子於燃料電池質子交換膜製備之應用

Sulfonated Polymers for the preparation of Proton Exchange Membranes in Fuel Cell

吳滄琪(Tsang-Chi Wu)

指導教授 ： 孫一明

元智大學/工程學院/化學工程與材料科學學系/碩士(2003年)

摘要

本研究利用多種膜材，包括磺酸化聚醚醚酮sulfonated poly(ether ether ketone) (SPEEK)、sulfonated poly(phthalazionone ether ketone) (SPPEK)膜材與PTFE-SPEEK、poly(tetrafluoroethylene) sulfonated polystyrene (PTFE-SaPS) 複合膜以製備用於燃料電池系統中之質子交換膜，在SPEEK、SPPEK膜材係以溶鑄法於玻璃板成膜；PTFE-SPEEK、PTFE-SaPS複合膜則利用多孔性聚四氟乙烯(PTFE)薄膜為基材，將 SPEEK與SaPS含浸於內成膜。本研究中所使用的鑑定方法包括薄膜離子導電度分析、薄膜結構電顯觀察、元素分析、FTIR官能基分析、水與甲醇的膨潤性與熱穩定性等測試的方法，並與Nafion-117膜材之相關性質作比較，以驗證其應用於燃料電池高分子電解質中之電極膜組的可行性。
由掃描式電子顯微鏡(SEM)之觀察：SPEEK與SPPEK 膜材均為緻密膜材，PTFE-SPEEK膜則有SPEEK披覆於PTFE內的證據。在尺寸安定實驗上，PTFE-SPEEK複合膜比SPEEK膜具有較佳的尺寸安定性。於甲醇膨潤性實驗中，SPPEK膜材比Nafion-117具有較低的吸附甲醇吸附量與較佳的尺寸安定性。
一般而言，離子導電度可隨膜材含水率與溫度增加而提高，若利用交流阻抗(AC Impedance)儀分析膜材離子導電度，在環境相對溼度為95 ％時，SPEEK7、SPEEK8、SPPEK膜材導電度都在10-3以上；PTFE-SPEEK7膜材離子導電度可接近1.1 ×10-2 S/cm，與Nafion-117膜之1.2 ×10-2 S/cm相當，應可用於燃料電池上質子交換膜的測試上。
氫、氧燃料電池測試：PTFE-SPEEK7膜材單電池測試結果，電
流密度在1400 mA/cm2時具有最大的電池功率0.56W/cm2；甲醇燃料電池測試：SPPEK膜電極組在電流密度為275 mA/cm2時有最佳電池功率密度為55 mW/cm2，與商業化膜組ElectroChem112 為32mW/cm2、ElectroChem117 為27mW/cm2 相比具有較好電池效能。

關鍵字

聚四氟乙烯 ； 磺酸化聚醚醚酮 ； 燃料電池 ； 質子交換膜 ； 膜電極組 ； 離子導電度

並列摘要

In this study, sulfonated poly(ether ether ketone) (SPEEK) and sulfonated poly(phthalazionone ether ketone) (SPPEK) were prepared on glass plates by solvent casting method; sulfonated atactic polystyrene (SaPS) and SPEEK were impregnated into porous poly(tetrafluoroethylene) (PTFE) membranes to prepare PTFE-SaPS and PTFE-SPEEK, respectively, composite membranes. The obtained membranes were tested for the application as proton exchange membranes (PEM) in fuel cell. A series of standard characterization methods were used to identify the membrane properties, such as AC impedance analysis, SEM observation, element analysis, FTIR, gas permeability, sorption uptake and swelling ratio in water and in methanol, and thermal analysis. The properties of membranes were compared with those of Nafion-117 with an aim to be used for the fabrication of membrane electrode assembly (MEA).
SEM observation confirmed that SPEEK was on the surface as well as in the inner pores of PTFE-SPEEK composite membranes. The composite membrane has better size stability than SPEEK membranes. SPPEK membranes showed lower methanol uptake and better size stability than Nafion-117 membranes.
The ion conductivity of the PEM increased as temperature, humidity, and degree of water uptake of the membranes. The ion conductivities of the SPEEK7, SPEEK8 and SPPEK membranes were higher than 1.0×10-3 S/cm at the humidity of 95 %. The ion conductivity of PTFE-SPEEK7 membrane (σ＝1.1×10-2 S/cm) was close to that of Nafion-117 membrane (σ＝1.2×10-2 S/cm). Based on all the tested results, PTFE-SPEEK7 membranes have potential to be used for PEMFC.
In the H2/O2 single fuel cell test, the membrane electrode assembly (MEA) made of PTFE-SPEEK7 showed the maximum power density of 0.56 W/cm2 when the current density was 1400 mA/cm2. In the direct methanol fuel cell (DMFC) test, the MEA of SPPEK showed the maximum power density of 55 mW/cm2 when the current density was 275 mA/cm2. The maximum power density of the MEA of SPPEK was better than that of ElectroChem-112 (32 mW/cm2) and ElectroChem-117 (27 mW/cm2)

並列關鍵字

PTFE ； sulfonated poly(ether ether ketone) ； fuel cell ； PEM ； MEA ； ion conductivity ； poly(phthalazionone ether ketone)

參考文獻

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