Superior electrochemical performances of LaMgNi alloys with A2B7/A5B19 double phase |
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| Affiliation: | 1. College of Chemistry and Chemical Engineering, Henan Polytechnic University, Jiaozuo 454000, PR China;2. State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, PR China;3. School of Materials Science & Engineering, Henan Polytechnic University, Jiaozuo 454000, PR China;4. School of Mechanical Engineering, Yangzhou University, Yangzhou 225127, PR China;1. School of Materials Science and Engineering, Guangdong Provincial Key Laboratory of Advanced Energy Storage Materials, South China University of Technology, Guangzhou, 510641, People''s Republic of China;2. China-Australia Joint Laboratory for Energy & Environmental Materials, Key Laboratory of Fuel Cell Technology of Guangdong Province, Guangzhou, 510641, People''s Republic of China;3. Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering (IAPME), University of Macau, Macau SAR, China;2. Faculté des Sciences de Tunis, Université de Tunis El Manar, 2092 El Manar, Tunis, Tunisia;1. College of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004, PR China;2. State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, PR China;1. State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, PR China;2. College of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004, PR China;3. Desert Vista High School, Phoenix, AZ 85048, USA;1. State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, PR China;2. College of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004, PR China;3. Department of Chemistry and Department of Physiology and Function Genomics, Center for Research at the Bio/Nano Interface, Shands Cancer Center and UF Genetics Institute, University of Florida, Gainesville, FL 32611-7200, United States;1. State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, PR China;2. College of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004, PR China |
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| Abstract: | Here, phase transformation and electrochemical characteristics of non-stoichiometry La4MgNix (x = 16, 17 and 18) hydrogen storage alloys were studied. It is found that after annealed at 1223 K for 24 h, the minor AB3 and AB5 phases in La4MgNi16 alloy transform into A2B7 phase by a peritectic reaction and the La4MgNi16 alloy shows a A2B7 single phase structure. Double phase structures of A2B7/A5B19 are obtained in La4MgNi17 and La4MgNi18 alloys after annealed at the same condition. The abundance of A5B19 phase increases as x increases, indicating the increasing x value contributes to the formation of A5B19 phases. Electrochemical studies show that the maximum discharge capacity and capacity retention at the 100th charge/discharge cycles (S100) of A2B7 single phase La4MgNi16 alloy is 373 mAh g−1 and 78.4%, respectively. The appearance of A5B19 (minor) phase in the La4MgNi17 alloy makes a remarkable improvement in the discharge capacity from 373 mAh g−1 to 388.8 mAh g−1, as well as the S100 from 78.4% to 90.1%. It is believed that the La MgNi-based alloy with the A2B7(main)/A5B19(minor) phase structure possesses the good overall electrochemical properties and is applicable to the high-power and long-cycle life negative electrode material for nickel metal hydride batteries. |
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| Keywords: | Phase composition Electrochemical characteristics Annealing temperature |
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