In order to examine the effects of structure stability on the degradation behaviors of multiphase La0.7Mg0.3Ni3 alloy,changes of the crystal structure and hydrogen storage properties after gas-solid cycling were inves...In order to examine the effects of structure stability on the degradation behaviors of multiphase La0.7Mg0.3Ni3 alloy,changes of the crystal structure and hydrogen storage properties after gas-solid cycling were investigated in detail.The structural analysis identifies that（La,Mg）Ni3（PuNi3-type） phase transforms to amorphous,i.e.,hydrogen-induced amorphization（HIA） occurs whereas LaNi5（CaCu5-type）,（La,Mg）2Ni7（Ce2Ni7-type）,and（La,Mg）5Ni19（Pr5Co19-type） phases still keep crystalline upon hydriding/dehydriding cycling.Partial amorphization remarkably affects both the gas-solid and electrochemical storage performances.The plateau of PCT curves becomes narrow and steep with cycling.Moreover,the maximum electrochemical capacity decreases notably after gas-solid hydrogenation repeats.The electrochemical capacity reduction could be ascribed to both drop of the maximum storage capacity and the slope of plateau induced by partial amorphization.For direct electrochemical cycling,it is suggested that the capacity decay is mainly attributed to HIA in the initial stage.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.51161015 and 51371094)the Application Technology Research and Development Foundation of Inner Mongolia(No.20111401)the Innovation Foundation of Inner Mongolia University of Science and Technology(No.2012NCL024)
文摘In order to examine the effects of structure stability on the degradation behaviors of multiphase La0.7Mg0.3Ni3 alloy,changes of the crystal structure and hydrogen storage properties after gas-solid cycling were investigated in detail.The structural analysis identifies that（La,Mg）Ni3（PuNi3-type） phase transforms to amorphous,i.e.,hydrogen-induced amorphization（HIA） occurs whereas LaNi5（CaCu5-type）,（La,Mg）2Ni7（Ce2Ni7-type）,and（La,Mg）5Ni19（Pr5Co19-type） phases still keep crystalline upon hydriding/dehydriding cycling.Partial amorphization remarkably affects both the gas-solid and electrochemical storage performances.The plateau of PCT curves becomes narrow and steep with cycling.Moreover,the maximum electrochemical capacity decreases notably after gas-solid hydrogenation repeats.The electrochemical capacity reduction could be ascribed to both drop of the maximum storage capacity and the slope of plateau induced by partial amorphization.For direct electrochemical cycling,it is suggested that the capacity decay is mainly attributed to HIA in the initial stage.
