Journal of Inorganic Materials ›› 2020, Vol. 35 ›› Issue (5): 549-555.DOI: 10.15541/jim20190190

Special Issue: 2020年能源材料论文精选(三) :太阳能电池、热电材料及其他

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Microstructure and Electrochemical Property of A2B7-type La0.3Y0.7Ni3.4-xMnxAl0.1 Hydrogen Storage Alloys

ZHENG Kun1,LUO Yongchun1,2(),DENG Anqiang1,YANG Yang1,ZHANG Haiming1   

  1. 1.Department of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, China
    2.State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China
  • Received:2019-04-30 Revised:2019-08-02 Published:2020-05-20 Online:2019-09-18
  • Supported by:
    National Natural Science Foundation of China(51761026)

Abstract:

La0.3Y0.7Ni3.4-xMnxAl0.1(x=0-0.5) hydrogen storage alloys were prepared by vacuum arc melting followed by homogenized annealing. Effect of Mn element on the microstructure, hydrogen storage behavior and electrochemical properties were systematically investigated via different methods. The results show that the microstructure of the annealed alloys closely relates to the Mn content. Higher Mn content facilitates the formation of Ce2Ni7 type phase until single phase structure of Ce2Ni7- type forms in the alloys with x≥0.3. With the increment of Mn content, the unit cell parameters (a, c) and unit cell volume (V) of Ce2Ni7- type phase increase, resulting in the hydrogen absorption platform pressure of the alloys decreasing from 0.079 MPa to 0.017 MPa and the hydrogen storage capacities reaching 1.268wt%-1.367wt%. The electrochemical properties are significantly improved with the addition of Mn. La0.3Y0.7Ni3.25Mn0.15Al0.1 alloy exhibits the highest discharge capacity (390.4 mAh·g -1). The capacity retention S100 of the alloys with x=0.15 and 0.5 are 86.03% and 88.01%, respectively, presenting good cycle stability. Meanwhile, high rate discharge ability (HRD900) of the as-prepared alloys is 71.53%-87.73%. It is shown that electrochemical reaction kinetics of the alloy electrodes is controlled by both the electron transfer at the electrode/ solution interface and the diffusion of hydrogen atoms in the alloy bulk.

Key words: La-Y-Ni based alloys, Mn substitution, hydrogen storage, electrochemical property

CLC Number: