中國有色金屬學(xué)報
ZHONGGUO YOUSEJINSHU XUEBAO
| 第18卷 第11期 總第116期 2008年11月 |
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文章編號：1004-0609(2008)11-2036-08
Al對La-Mg-Ni系貯氫合金電極電化學(xué)性能的影響
江冰潔1，王 敬1, 2，穆道斌1, 2，陳 實1, 2，吳伯榮1, 2，吳 鋒1, 2
(1. 北京理工大學(xué) 化工與環(huán)境學(xué)院 環(huán)境科學(xué)工程北京重點實驗室，北京 100081；
2. 國家高技術(shù)綠色材料發(fā)展中心，北京 100081)
摘 要: 采用固相擴散法制備La0.7Mg0.3Ni3.5−xAlx(x=0, 0.1, 0.3, 0.7, 1.0)和La0.7Mg0.3Ni2.8Co0.7−xAlx (x=0, 0.1, 0.2, 0.3, 0.4)貯氫合金，采用X射線衍射、能譜分析及循環(huán)伏安等方法分析合金的相結(jié)構(gòu)和電極電化學(xué)性能，研究元素Al替代對合金電化學(xué)性能的影響。結(jié)果表明：合金由LaNi5、La2Ni7和LaNi3三相組成，隨著Al替代量的增加，La2Ni7相晶胞逐漸膨脹，LaNi5相大量減少，LaNi3相增加，La2Ni7相有利于合金電化學(xué)性能的提高，然而過高的Al含量會對合金的放電性能帶來不利影響。La0.7Mg0.3Ni3.4Al0.1和La0.7Mg0.3Ni2.8Co0.6Al0.1合金電極的最大放電容量分別為354.5 mA∙h/g和373.1 mA∙h/g。循環(huán)伏安測試顯示較明顯的氧化峰和還原峰，且峰電位差較小，反映合金電極較好的吸放氫反應(yīng)可逆性。
關(guān)鍵字: La-Mg-Ni-Al；La-Mg-Ni-Co-Al；貯氫合金；Al替代
Effect of Al substitution on electrochemical performance of La-Mg-Ni hydrogen storage alloys
JIANG Bing-jie1, WANG Jing1, 2, MU Dao-bin1, 2, CHEN Shi1, 2, WU Bo-rong1, 2, WU Feng1, 2
（1. Beijing Key Laboratory of Environmental Science and Engineering, School of Chemical Engineering and the
Environment, Beijing Institute of Technology, Beijing 100081, China;
2. National Development Center of High-technology Green Materials, Beijing 100081, China）
Abstract:La0.7Mg0.3Ni3.5−xAlx (x=0, 0.1, 0.3, 0.7, 1.0) and La0.7Mg0.3Ni2.8Co0.7−xAlx (x=0, 0.1, 0.2, 0.3, 0.4) hydrogen storage alloys were prepared by solid diffusion reaction under Ar atmosphere. The phase structures of alloys were analyzed by X-ray diffraction (XRD), as well as the electrochemical performance of alloy electrode with cyclic voltammetry(CV)and charge/discharge test, so as to investigate the effect of Al substitution on electrode characteristics. The results show that all alloys are composed of LaNi5，La2Ni7 and LaNi3 phases. With the increase of x value, the cell volume of La2Ni7 phase enlarges and the content of LaNi5 phase becomes low markedly, while the content of LaNi3 phase increases. La2Ni7 phase can be favorable to improve charge/discharge properties of alloy electrode. However, excessive content of Al has a negative impact on the discharge performance of alloys. The maximum values are 354.5 mA∙h/g and 373.1 mA∙h/g for La0.7Mg0.3Ni3.4Al0.1 and La0.7Mg0.3Ni2.8Co0.6Al0.1 electrodes, respectively. Cyclic voltammetry results indicate that the significant peaks responding to oxidation and reduction reactions and small difference between peak potentials mean good reversibility of the electrode during charge/discharge reaction.
Key words: La-Mg-Ni-Al; La-Mg-Ni-Co-Al; hydrogen storage alloys; Al substitution
