射出成型及射出壓縮成型燃料電池高分子雙極板製程特性與導電品質之研究

Study on the Characteristics and Conductivity Qualities of Injection and Injection - Compression Molded Bipolar Plates for Fuel Cells

李平惠(Ping-Hui Lee)

指導教授 ： 陳夏宗 ； 黃健生

中原大學/工學院/機械工程學系/博士(2008年)

https://doi.org/10.6840/cycu200900028

摘要

燃料電池(Fuel Cell)是一種對地球生態污染性較低且發電效率較高的能源，而雙極板(Bipolar Plate)佔據全部電池大半主體，是燃料電池的主要元件。以高分子導電性複合材料成型之雙極板，具有重量輕、抗腐蝕佳、成本低、加工快的優點，若能於導電度上有所突破，就能逐漸取代石墨或金屬雙極板。
本研究先以透明PC添加少量碳纖維(CF)，以一般製程參數成型為平板成品，做初步碳纖維配向與分佈觀察之基礎實驗。而後選取PPS+50wt.%CF 高分子導電性複合材料，藉由改變射出成型製程參數（模溫、料溫、射出速度與保壓壓力），探討傳統射出成型與射出壓縮成型製作無流道平板製程中，對碳纖維配向、分佈與導電性之影響。其次對添加不同比例之石墨(GP)高分子複合材料在不同成型條件造成碳纖維配向、分佈與導電性之影響加以探討。另外，流道配置方向對碳纖維配向、分佈以及導電度之影響亦加以研究，並評估出理想的成型條件。導電性量測項目包括平面導電度(In-Plane Conductivity)與穿透電阻(Through-Plane Resistance)，並以掃描式電子顯微鏡(SEM)與3D-CAE模擬分析觀察纖維配向與分佈情形。
綜合以上研究，傳統射出成型較佳化參數為：模溫210℃、料溫330℃、射速60mm/s、保壓150MPa，穿透電阻下降53%，平面導電度上升48%。射出壓縮成型較佳之開模間距為0.8mm，穿透電阻下降38%，平面導電度上升61%。基材添加20wt.%GP，以射出壓縮成型後，平面導電度為156S/cm，已達到國際DOE之標準。流道配置垂直充填方向以射出壓縮成型，平面導電度提升至183S/cm，達到本研究目的之關鍵要求。

關鍵字

配向 ； 碳纖維 ； 射出/射壓成型 ； 雙極板

並列摘要

Fuel cells constitute one of the most promising sources of clean energy and bipolar plate is an important component of a fuel cell. Electrically conductive polymer composites for molding of bipolar plates, has the advantages of lightweight, low cost, chemical stability, and ease of fabrication. They will can alternative to graphite and metal-based material if one can improve the conductivity of polymer composite.
In this study, bipolar plates without channel were injection molding using PC polymer filled with a few carbon fiber to investigate the fiber orientation and distribution from molding condition. Then the plates with and without channels were convectional injection molding (CIM) and injection-compression molding (ICM) using PPS polymer filled with 50 wt% carbon fiber (and different content of graphite) under different molding parameters was addressed. The effect of molding methods (CIM and ICM) and processing parameters including mold temperature, melt temperature, injection velocity, and packing pressure on the electrical conductivity performance were analyzed and correlated. Meanwhile, influence of fiber orientation and distribution from molding conditions was evaluated. How flow channel design affects the conductivity distribution was also studied as well. The in-plane conductivity and through-plane resistance of the bipolar plate was done by four-point probe apparatus and micrograph was done via SEM. In addition, 3D-CAE simulation for fiber orientation and dispersion phenomenon during filling process was also investigated and compared with injection molding experiment.
The results showed that through-plane resistance and in-plane conductivity of the bipolar plate can drop 53% and improve 48%, respectively, when the better molding condition was chosen (mold temperature 210℃, melt temperature 330℃,injection velocity 60mm/s, packing pressure 150MPa) for CIM. In addition, when ICM with 0.8 mm initial open gap, it can decreases 38% and increases 61% for through-plane resistance and in-plane conductivity, respectively. At a graphite level of 20 wt%, the in-plane conductivity can reached 156S/cm and it has been achieved the DOE target. As channel is perpendicular to filling direction for ICM, the in-plane conductivity can reached 183S/cm.

並列關鍵字

injection/compression molding ； orientation ； carbon fiber ； bipolar plate

參考文獻

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