射出成型製備燃料電池雙極板導電性提升之研究

Study on Conductivity Enhancement of PEMFC Bipolar Plates Molded by Injection Molding

鄭至凱(Chui-Kai Cheng)

指導教授 ： 陳夏宗

中原大學/工學院/機械工程學系/碩士(2007年)

https://doi.org/10.6840/cycu200700597

摘要

能源耗竭與環境汙染的背景下，燃料電池(Fuel Cell)是極具潛力的潔淨能源之一，其組件中雙極板(Bipolar Plate)占整體成本三成且重量為整體之八成。複合材料雙極板搭配射出成型技術因製程簡單、快速量產且成本低廉最受青睞，可逐漸取代石墨與金屬雙極板。而複合材料射出成型目前少有針對材料、製程與後加工之整體性研究，且導電性仍有待提升。
　　研究中以複合材料PPS+50wt.%碳纖維，配合製程參數(料溫、射速、模溫、保壓變化)、射出壓縮成型(開模間距變化)、噴砂研磨後加工與材料變更(PPS+20wt.%碳纖維+30wt.%石墨)四種條件進行實驗，探討影響導電性之主要因素並藉以提升導電性。量測部分針對平面導電度(In-Plane Conductivity)與穿透電阻(Through-Plane Resistance)進行量測，並以掃描式電子顯微鏡(SEM)觀察纖維定向情形並與導電性作探討。
　　研究結果顯示，傳統製程參數於較佳化時(高料溫330℃、低射速60mm/s、高模溫210℃、高保壓壓力90%)穿透電阻可降低44%，而平面導電度則由60 S/cm提升至75 S/cm。射出壓縮成型可提高內部纖維之交錯性，研究中預開模間距於0.8mm時，其穿透電阻可降低38%，平面導電性則可提升至73 S/cm。噴砂研磨後加工方式可減薄高分子含量高之皮層厚度，於厚度減少0.01mm時穿透電阻有27%之下降，而平面導電度因粗糙度提高因而無法量測。最終以材料變更搭配較佳化製程參數與預開模0.8mm射出壓縮製程再搭配噴砂研磨，其穿透電阻有下降87%之改善，平面導電度則有53%之提升且已達123 S/cm超過國際DOE標準。本研究搭配材料配方、特殊製程、後加工處理之結合，可有效改善射出成型雙極板無法成型高含碳量材料之問題，進而成功達到提升導電性之最大效益。

關鍵字

射出/射出壓縮成型 ； 噴砂研磨 ； 導電性複合材料 ； 雙極板

並列摘要

Fuel cells constitute one of the most promising sources of clean energy for the future. The PEMFC is the most popular in fuel cells because of low operation temperature, widely application and so on. A significant part of the PEMFC fuel cell stack is the bipolar plates (BPPs), which amount for about 80% of total weight and 30% of total stack cost. Because of weight and cost reduction, carbon composite and injection molding have been identified as the most promising technology. However, it must to be improving electrical conductivity first.
　In this study, injection molding of 50wt. % carbon-filled PPS was used to fabricate BPPs. And process parameter, injection-compression molding (ICM), abrasive blasting and material change were investigated. Conductivity is directly calculated from in-plane and through-plane resistance measurement of the plates. Finally, we investigated the relationship between conductivity and fiber orientation by taking cross-section SEM micrographs of BPPs.
　The study results showed that process parameter change can improve 44% of through-plane resistance and bulk conductivity will reach 75 S/cm from 60 S/cm. When ICM with initial open gap 0.8mm, it can improve 38% of through-plane resistance and reach 73 S/cm of bulk conductivity. Abrasive blasting can break a polymer rich skin on the plate surface. It can improve 27% of through-plane resistance when remove approximately 0.01mm. Material change with the better parameter and process can improve the resistance most. The improvement of through-plane resistance is 87% and in-plane resistance is 53%. The bulk conductivity reached 123 S/cm, it has already achieved DOE target. So, combination of all is the most important to improve conductivity. The pros and cons of these four conditions will be discussed in detail.

並列關鍵字

Polymer Composite ； Injection Molding ； Injection-Compression Molding ； Bipolar Plate

參考文獻

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