Effect of cobalt substitution for nickel on microstructural evolution and hydrogen storage properties of La_(0.66)Mg_(0.34)Ni_(3.5-x)Co_(x) alloys  

作　　者：Xincong He Huazhou Hu Ruizhu Tang Wenhao Zhou Houqun Xiao Xiaoxuan Zhang Chuanming Ma Qingjun Chen 

机构地区：[1]School of Rare Earths,University Science&Technology of China,Hefei,230026,China [2]Key Laboratory of Rare Earths,Chinese Academy of Sciences,Jiangxi Institute of Rare Earths,Ganjiang Innovation Academy,Chinese Academy of Sciences,Ganzhou,341000,China

出　　处：《Journal of Rare Earths》2024年第5期930-939,I0004,共11页稀土学报（英文版）

基　　金：Project supported by the National Key R&D Program of China(2022YFB3504700)。

摘　　要：Superlattice hydrogen storage alloys offer a compelling advantage with rapid hydriding rate and high storage capacity.However,its practical applications face challenges including complex structure,low dehydriding capacity,and cyclic instability.In this work,we successfully prepared La_(0.66)Mg_(0.34)Ni_(3.5-x)Co_(x) superlattice hydrogen storage alloys with enhanced dehydriding capacity and stability by partially substituting Co for Ni.X-ray diffraction(XRD)refinements analysis reveals the presence of(La,Mg)_(3)Ni_(9),(La,Mg)_5Ni_(19),and LaNi_(5) phases within the alloy.Following Co substitution in the La_(0.06)Mg_(0.34)Ni_(3.4)Co_(0.1)alloy,there is a significant increase in content of the(La,Mg)_(3)Ni_(9) phase and a reduction in the hysteresis factor,resulting in an improved reversible hydrogen storage capacity from 1.45 wt%to 1.60 wt%.The dehydriding kinetics of the alloy is controlled by diffusion model with an activation energy of 8.40 kJ/mol.Furthermore,the dehydriding enthalpy value of the Co-substituted alloy decreases from 30.84 to 29.85 kJ/mol.Impressively,the cycling performance of the alloy after Co substitution exhibits excellent stability,with a capacity retention rate of 92.3%after 100 cycles.These findings provide valuable insights for the development of cost-effective hydrogen storage materials.

关 键 词：Superlattice hydrogen storage alloy Co substitution Microstructure Kinetics Thermodynamics Rare earths 

分 类 号：TG1[金属学及工艺—金属学]