鎂基儲氫合金之儲放氫特性與電極特性之開發應用研究; On the Study of Properties and Electrode in Mg Base Hydogen Storage Alloys

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題名:	鎂基儲氫合金之儲放氫特性與電極特性之開發應用研究;On the Study of Properties and Electrode in Mg Base Hydogen Storage Alloys
作者:	李勝隆
貢獻者:	機械工程學系
關鍵詞:	儲氫合金;動力學;Hydrogen storage materials;Kinetics;Ni-MH electrode;IECP;材料科技;能源工程
日期:	2010-08-01
上傳時間:	2011-07-12 13:57:30 (UTC+8)
出版者:	行政院國家科學委員會
摘要:	具低污染與高能量密度之氫能，實為下世代最具潛力之新型能源。而氫氣儲存是氫能應用不可或缺的環節。由於儲氫材料具多項優點而引起全球廣泛研究。美國能源部（US-DOE）於2003 年起，已成立三個氫能測試中心，2007 年又尋求設立儲氫工程中心。而我國行政院『2007 年產業科技會報』，將成立四年期「能源國家型科技計畫」，每期至少投入上百億預算。其中儲氫科技列為前瞻能源研究項目之一。申請人基於氫能的潛在應用價值，結合理論研究與實務經驗，將進行鎂基儲氫合金之開發應用研究。 Mg 金屬、Mg-Mg2Ni 共晶合金和Mg2Ni 中間相的儲氫量分別為7.6wt%, 5.7wt%與3.6wt%，均遠高於目前商用的LaNi5（儲氫量1.4wt.%），且其具重複充放氫特性、理論電極放電容量大（Mg2Ni 理論電容量為999mAh/g），密度小、資源豐富、價格合理等優點，所以其研發成果一直受到高度注意。儘管有這些優點，但 Mg 活性高，亦面臨到：製備不易、儲放氫動力學不佳、實際電極放電容量低（Mg2Ni 實際電容量為8 mAh/g）等問題。所以國內外之研究焦點幾乎是集中在解決上述的三個問題上。申請人利用本校經費與國科會前期之補助，建立有效、廉價之設備與技術---恆溫蒸發鑄造製程(IECP)，成功製作鎂基(Mg2Ni 合金與Mg/Mg2Ni 共晶合金）儲氫合金，其製備技術應屬全球領先地位。同時已於本校建立諸多製備、與特性測試設備，也堪稱國內此領域中最完備者。本計劃擬就現有基礎進行三年期的研究規劃，研究目標為：提升Mg（-Ni）合金之儲放氫動力學、與提升實際電極放電容量。主要的研究方法是藉由（合金製備變化）導入合金缺陷、與催化劑的添加兩種途徑，期望能對“鎂基輕合金之開發與應用”提供一有價值的學術與應用參考：三年之規劃為： (1)利用自有的IECP 法，於合金中加入第三或第四元素如(Ti、V、Cr、Cu、Mn、Al)，來部分取代Mg 與Ni，探討元素取代對於儲放氫特性與電極放電容量之影響。 (2)利用機械合金法（MA）與自有專利之等通道擠型（CCEP）法，就上述之合金進行加工，製備具奈米晶與高缺陷之儲氫合金，探討儲放氫特性與電極放電容量之影響。 (3) 利用微量儲氫中間相（LaNi5、TiFe 等）、催化劑（CeO、TiO2 等）的添加與加工變化，探討儲放氫特性與電極放電容量之影響。上述的規劃內容充實，且與申請人長期研究方向具一貫性，申請人從事輕合金研究已逾25 年，對於Al、Mg、Ti 合金之特性有深入感受，儲氫材料雖屬申請人三年前才開始之研究領域，但其研究材料、方法並無差異。目前研究者鮮少就儲氫材料微結構變化對其動力學與電化學特性進行探討，研究較缺乏系統性，申請人所開發的IECP 法將能簡易配製Mg(-Ni)合金，對於後續探討多元合金與合金加工之影響，具有極佳之機動性。另外，本校亦將儲氫材料之研發列為重點支持項目。對於本申請案之進行將本諸以往之研究基礎，努力完成設定之目標，期能對儲氫合金之製造、應用，提供有益之參考。 Hydrogen is the ideal candidate as an energy carrier for mobile and stationary applications due to environmental concerns of the harmful emissions from the fossil fuels used presently. Hydrogen storage is clearly one of the key challenges in developing hydrogen economy. The US Department of Energy(US-DOE) published to establish the 4th hydrogen storage center in 2007. Our government has announced a 4-year period National-Energy project to develop the hydrogen energy, which include the hydrogen storage. The objective of this proposal is to develop magnesium-based alloys for high-capacity hydrogen storage and higher density Ni-MH electrode material. The theoretical storage capacity and discharge capacity of Mg2Ni are 3.6wt% and 999 mAh/g, respectively. Moreover, Mg has a low density, is abundant in nature, and has a reasonable price. The main problem of Mg is that it oxidizes readily, and deteriorates its hydrogen storage characteristics and smaller discharge capacity. There are several obstacles against the implementation of Mg-based alloys as a successful hydrogen material. The first is that the manufacturing of bulk Mg2Ni material is difficult because Mg has a high vapor pressure. Secondly, a relatively high temperature (around 300 oC) is needed in order to have a reasonable hydriding and de-hydriding kinetics. Third, the problems related to the poor discharge capacity of Mg2Ni are still un-clear. To improve the characteristics of Mg-base hydrogen storage alloys, the researchers have focused their study on the following 3 fields: manufacturing, kinetics and electrode. A new method for producing Mg-base alloy on mass production had been carried out by us, through the natural chacteristics and spontaneous reaction referring to Mg-Ni phase diagram. Isothermal Evaporation Casting Process (IECP), is proposed to produce functional Mg-based intermetallic compounds. In the past, high vapor pressure of Mg was considered as a disadvantage for producing single phase Mg-based intermetallic compounds by conventional melting. However, this characteristic was used to develop a refinement procedure to separate the formed primary Mg2X (X=Ni、Cu、Si、Sn) from Mg/Mg2X eutectic matrix and produce Mg2X alloys in high productivity. In this proposed research, a 3-year period research is organized to attack the 2rd & 3rd obstacles listed above, with the following three focused topics: 1.Add 3rd (or 4th) elements (ex. Ti, V,Cr,Cu,Mn,Al etc..)to partly substitute Mg and Ni by the IECP processing. 2.Deveop the nanocrystalline and/or higher defects hydrogen storage by MA and CCEP processing. 3.Add the catalysts to improve the kinetics and electrode property of Mg(-Ni) base alloys. One key feature of this proposed research is integration, substantiation and consistent. We hope that such an integrated proposal will offer researchers and users a useful reference to solving a complicated problem we have at hand. 研究期間：9908 ~ 10007
關聯:	財團法人國家實驗研究院科技政策研究與資訊中心
顯示於類別:	[機械工程學系] 研究計畫

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