Journal of Inorganic Materials ›› 2018, Vol. 33 ›› Issue (4): 434-440.doi: 10.15541/jim20170222

• Orginal Article • Previous Articles     Next Articles

Annealing Temperature on Structural and Electrochemical Property of Mg-free La-Y-Ni Based A2B7-type Hydrogen Storage Alloys

Hao WANG1(), Yong-Chun LUO1,2(), An-Qiang DENG1, Lei ZHAO1, Wan-Ting JIANG1   

  1. 1. School 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:2017-05-04 Revised:2017-07-14 Online:2018-04-30 Published:2018-03-27
  • About author:WANG Hao. E-mail: 317003562@qq.com
  • Supported by:
    National High-tech R&D Program of China (863 Program) (2011AA03A408);National Natural Science Foundation of China (51761026)

Abstract:

Effects of annealing temperature on the microstructure and electrochemical properties of A2B7-type La0.33Y0.67Ni3.25Mn0.15Al0.1 hydrogen storage alloys were systematically investigated by XRD, SEM, EDS, and electrochemical measurements. Results showed that the alloy was composed of CaCu5-type, 2H-Ce2Ni7-type, 3R-Gd2Co7 -type and 3R-Ce5Cu19-type phases. Both abundance and unit cell volume of Ce2Ni7-type phase increased gradually with the anneale temperature increase when the annealing temperature was lower than 950℃. CaCu5-type and Gd2Co7-type phases disappeared at 950℃, but both abundance and unit cell volume of the Ce2Ni7-type phase maximized. When annealing temperature was higher than 950℃, Ce2Ni7-type phase decreased while Ce5Co19 type phase increased. The alloy, annealed at 950℃, had the lowest hydrogen desorption platform pressure (0.0192~0.087 atm), maximum hydrogen storage capacity (1.35wt%) and high electrochemical discharge capacity (371 mAh/g) with the maximum capacity retention S100 at 89% after 100 cycle. The high rate discharge ability (HRD) of the annealed alloys were significantly improved, the alloy annealed at 950℃ had the best performance and HRD900 was up to 83.4%. These well performances demonstrated that it is the hydrogen diffusion in the alloys that controls the high rate discharge.

Key words: hydrogen storage materials, La-Y-Ni-based electrode material, heat treatment, microstructure, electrochemical properties

CLC Number: 

  • TG146