无机材料学报 ›› 2018, Vol. 33 ›› Issue (4): 434-440.DOI: 10.15541/jim20170222 CSTR: 32189.14.10.15541/jim20170222

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退火温度对无镁La-Y-Ni系A2B7型合金相结构和电化学性能的影响

王浩1, 罗永春1,2, 邓安强1, 赵磊1, 姜婉婷1   

  1. 兰州理工大学1. 材料科学与工程学院;
    2. 有色金属先进加工与再利用省部共建国家重点实验室, 兰州 730050
  • 收稿日期:2017-05-04 修回日期:2017-07-14 出版日期:2018-04-30 网络出版日期:2018-03-27
  • 作者简介:王 浩(1992-), 男, 硕士研究生. E-mail: 317003562@qq.com
  • 基金资助:
    国家高技术863计划项目(2011AA03A408);国家自然科学基金(51761026)

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

WANG Hao1, LUO Yong-Chun1,2, DENG An-Qiang2, ZHAO Lei2, JIANG Wan-Ting1   

  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 Published:2018-04-30 Online: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)

摘要:

用XRD、SEM、EDS和电化学测试方法研究了退火温度对A2B7型La0.33Y0.67Ni3.25Mn0.15Al0.1储氢合金微观组织和电化学性能的影响规律。结果表明, 合金铸态组织由2H-Ce2Ni7、3R-Gd2Co7、CaCu5和3R-Ce5Co19型相组成; 随退火温度(850~950℃)升高, Ce2Ni7型主相丰度和晶胞体积逐渐增加, 至950℃退火后, CaCu5和Gd2Co7型相基本消失, 主相Ce2Ni7型相丰度和晶胞体积均达到最大值; 退火温度≥950℃时, Ce2Ni7型和Ce5Co19型相丰度分别又有所减少和增加。950℃退火合金具有较低的放氢平台压(1.92~8.70 kPa)和较高的电化学放电容量(371 mAh/g), 经100次充放电循环后其容量保持率S100达到89%。退火合金电极的HRD性能均得到不同程度的提高, 其中950℃退火合金具有最佳的大电流放电性能(HRD900=83.4%)。氢在合金中的扩散是影响其高倍率放电性能的控制因素。

 

关键词: 储氢合金, La-Y-Ni系电极材料, 热处理, 微观组织, 电化学性能

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

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