Hydrogen storage properties of as-cast and annealed low-Co La1.8Ti0.2MgNi8.9Co0.1 alloys

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• 作者：Wei-Qing Jiang ; Jin Guo ; Zheng-Cheng Zhou ; Yin-Yan Wei
• 刊名：Rare Metals
• 出版年：2016
• 出版时间：July 2016
• 年：2016
• 卷：35
• 期：7
• 页码：559-565
• 全文大小：1,191 KB
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Chemistry
  Metallic Materials
  Chinese Library of Science
  
• 出版者：Journal Publishing Center of University of Science and Technology Beijing, in co-publication with Sp
• ISSN：1867-7185
• 卷排序：35

文摘

Low-Co La_1.8Ti_0.2MgNi_8.9Co_0.1 alloys were prepared by magnetic levitation melting followed by annealing treatment. The effect of annealing on the hydrogen storage properties of the alloys was investigated systematically by X-ray diffraction (XRD), pressure-composition isotherm (PCI), and electrochemical measurements. The results show that all samples contain LaNi₅ and LaMg₂Ni₉ phases. LaCo₅ phase appears at 1,000 °C. The enthalpy change of all hydrides is close to −30.6 kJ·mol−1 H₂ of LaNi₅ compound. Annealing not only increases hydrogen capacity and improves cycling stability but also decreases plateau pressure at 800 and 900 °C. After annealing, the contraction of cell volume and the increase of hydride stability cause the high rate dischargeability to reduce slightly. The optimum alloy is found to be one annealed at 900 °C, with its hydrogen capacity reaching up to 1.53 wt%, and discharge capacity remaining 225.1 mAh·g−1 after 140 charge–discharge cycles.KeywordsLa–Mg–Ni-based alloyAnnealing treatmentHydrogen storageElectrochemical characterization