無電鍍鎳合金應用於直接甲醇燃料電池陽極雙極板之研究

Electroless Ni-based Alloy as Anode Coating Material for Direct Methanol Fuel Cell

林哲宇(Che-Yu Lin)

指導教授 ： 王詠雲 ； 萬其超

國立清華大學/工學院/化學工程學系/碩士(2008年)

摘要

本論文主要以無電鍍法製備低電阻率及耐腐蝕性高之Ni-P薄膜作為金屬表面改質之材料以取代傳統石墨製雙極板來減少燃料電池的重量、體積與成本的花費及其在直接甲醇燃料電池上之應用可行性分析之探討。
所得到的無電鍍鎳磷薄膜用EDX分析組成為Ni：85-87 at.%、 P：13.5-14.9 at.%且四點探針(Four-point probe)的數據顯示電阻率介於54-95 μΩ-cm間。此外，薄膜會利用電子顯微鏡(SEM)、X-ray粉末繞射(XRD)及動態電位極化法(Potentiodynamic test)來研究薄膜表面的型態、微結構及腐蝕的性質。
由動態電位極化法(Potentiodynamic test)實驗結果顯示，當磷成份含量高及鍍層結構為無晶形時，在直接甲醇燃料電池的陽極端模擬環境中(0.5M硫酸 + 10vol % 甲醇水溶液)，具有較惰性的腐蝕電位，此外經過10小時的定電位測試(Potentiostat test, -0.1V vs. 甘汞電極)，電流均呈現負值，表示在我們的系統中提供了類似”陰極保護(Cathodic protection)”的功能；此外，利用ICP-MS分析長時間定電位測試後的溶液，沒有發現溶液內有任何的金屬離子存在，表示沒有腐蝕現象的發生，再者，將鍍層實際應用在DMFC上，實驗結果顯示可以提高電池約18%的性能。除了上述的結果，利用無電鍍進行表面改質具有較其他物理方法如物理氣相沉積法(PVD)等操作方便且成本較低的優勢，因此有相當大的潛力可應用於直接甲醇燃料電池雙極板的開發。

關鍵字

無電鍍 ； 燃料電池 ； 陰極保護法

並列摘要

Our study is to develop a coating with low resistivity and high corrosion resistance to protect the metallic substrate, which serves to replace the traditional graphite material to reduce the weight, volume and cost for direct methanol fuel cell (DMFC).
The elemental composition of the electrolessly deposited Ni-P coating in this report has been determined to be Ni : 85-87 at.%, P : 13.5-14.9 at.% by EDX. And four-point probe results show the resistivity of the coatings to be around 54-95 μΩ-cm. In addition, various analytical methods were employed including, the surface morphology study by SEM, crystal structure by XRD and corrosion properties by potentiodynamic test.
The results of potentiodynamic test reveal that Ni-P coating with higher P content and amorphous structure shows nobler corrosion potential than other materials in the simulated anode working environment (0.5M H2SO4 + 10vol % methanol solution). And the potentiostat test shows the negative corrosion current at all times (-0.1V vs. SCE), meaning the negative current provides “cathodic protection” in our system. After analyzing the electrolyte for 10 hrs by potentiostatic test, no metal ions were found in the solution. Besides, the real DMFC performance test shows excellent performance than commercial one (about 18% growth). Since, the electroless deposition method is more easily controlled and less expensive than the PVD or CVD processes, it has high potential as corrosion protection coating for DMFC bipolar plate.

並列關鍵字

Electroless ； Fuel Cell ； Cathodic protection

參考文獻

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