退火温度对无镁La-Y-Ni系A_2B_7型合金相结构和电化学性能的影响  

Annealing Temperature on Structural and Electrochemical Property of Mg-free La-Y-Ni Based A_2B_7-type Hydrogen Storage Alloys

作　　者：王浩[1] 罗永春[1,2] 邓安强 赵磊 姜婉婷 WANG Hao;LUO Yong-Chun;DENG An-Qiang;ZHAO Lei;JIANG Wan-Ting(School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, China;State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China)

机构地区：[1]兰州理工大学材料科学与工程学院,兰州730050 [2]兰州理工大学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

出　　处：《无机材料学报》2018年第4期434-440,共7页Journal of Inorganic Materials

基　　金：国家高技术863计划项目(2011AA03A408);国家自然科学基金(51761026)~~

摘　　要：用XRD、SEM、EDS和电化学测试方法研究了退火温度对A_2B_7型La_(0.33)Y_(0.67)Ni_(3.25)Mn_(0.15)Al_(0.1)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-Ce_2Ni_7、3R-Gd_2Co_7、CaCu_5和3R-Ce_5Co_(19)型相组成;随退火温度(850~950℃)升高,Ce_2Ni_7型主相丰度和晶胞体积逐渐增加,至950℃退火后,CaCu_5和Gd_2Co_7型相基本消失,主相Ce_2Ni_7型相丰度和晶胞体积均达到最大值;退火温度≥950℃时,Ce_2Ni_7型和Ce_5Co_(19)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 k Pa)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。Effects of annealing temperature on the microstructure and electrochemical properties of A2B7-type Lao.33Y0.67Ni3.zsMnoAsA10.1 hydrogen storage alloys were systematically investigated by XRD, SEM, EDS, and electrochemical measurements. Results showed that the alloy was composed of CaCus-type, 2H-Ce2Niy-type, 3R-Gd2Co7 -type and 3R-CesCulg-type phases. Both abundance and unit cell volume of Ce2Niy-type phase increased gradually with the anneale temperature increase when the annealing temperature was lower than 950℃. CaCus-type and Gd2CoT-type phases disappeared at 950℃, but both abundance and unit cell volume of the Ce2NiT-type phase maximized. When annealing temperature was higher than 950℃, Ce2Niy-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.

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 

分 类 号：TG146[一般工业技术—材料科学与工程]