基于密度泛函理论,采用总能量平面波赝势方法,设计了Lao.75 Mg0.25Ni3.5-xCox(x=0、0.25、0.5、0.75)系列合金,并研究了其晶体及电子结构,计算结果显示随着Co含量的增加,La原子上的电荷转移先增大后保持不变,在Co含量为0.5时达到最大；费米能级处的态密度值先增加后稍减小,Co含量在0.5时达到最大.利用悬浮感应熔炼法制备了该系列合金La0.75Mg0.25Ni3.5-xCox (x=0、0.3、0.5、0.7).对熔炼所得合金进行了结构和性能表征,XRD结果显示,随着Co含量的增加,合金的主相均为Ce2Ni7型AB3.5相；电化学测试显示,x=0.5时,合金的放电容量和循环性能均较好,为398.5 mAh/g,容量保持率S250为62％; PCT结果表明,在室温条件下合金的吸氢平台在0.04～0.09 MPa之间,当x=0.5时,吸氢平台压最低,为0.04 MPa,同时吸氢量最大,为1.587wt％.综合分析计算和实验的结果,AB3.5合金性能随Co添加量的变化趋势符合第一性原理计算的预测.
参考文献
| [1] | Ovshinsky S R,Fetcenko M A,Ross J.A nickel metal hydride battery for electric vehicles.Science,1993,260(5105):176-181. |
| [2] | Kim D M,Jang K J,Lee J Y.A review on the development of AB2-type Zr-based Laves phase hydrogen storage alloys for Ni-MH rechargeable batteries in the Korea Advanced Institute of Science and Technology.J.Alloys Compd.,1999,293-295:583-592. |
| [3] | Kadir K,Sakai T,Uahara I.Structural investigation and hydrogen capacity of YMg2Ni9 and (Y0.5Ca0.5)(MgCa)Ni9:new phases in the AB2C9 system isostructural with LaMg2Ni9.J.Alloys Compd.,1999,287(1/2):264-270. |
| [4] | Yamamoto T,Inui H,Yamaguchi M,et al.Microstrutures and hydrogen absorption/desorption properties of La-Ni alloys in the composition range of La-77.8-83.2at％Ni.Acta Mater.,1997,45(12):5213-5521. |
| [5] | Levin E,Donskoy P,Lushnikow S,et al.Hydrogen sorption and electrochemical properties of intermetallic compounds La2Ni7 and La2Ni6Co.Hydrogen Materials Science and Chemistry of Carbon Nanomaterials,2004:503-510. |
| [6] | Wang D H,Luo Y C,Yan R X,et al.Phase structure and electrochemical properties of Lao67Mg0.33Ni3.0-xCOx(x=0,0.25,0.5,0.75)hydrogen storage alloys.J.Alloys Compd.,2006,413(1/2):193-197. |
| [7] | Zhang F L,Luo Y C,Sun K,et al.Effect of Co content on the structure and electrochemical properties of La1.5Mg0.5Ni7-Cox (x=0,1.2,1.8) hydrogen storage alloys.J.Alloys Compd.,2006,424(1/2):218-224. |
| [8] | Dong X P,Zhang Y H,Lu F X,et al.Investigation on microstructures and electrochemical performances of La10.75Mg0.25Ni3.5-xCox (x=0-0.6) hydrogen storage alloys.Int.J.Hydrogen Energy,2007,32(18):4949-4956. |
| [9] | Chai Y J,Sakaki K,Asano K,et al.Crystal structure and hydrogen storage properties of La-Mg-Ni-Co alloy with superstructure.Scipta Mater.,2007,57(6):545-548. |
| [10] | Hasnip PJ,Probert MJ,Refson K,et al.First principles methods using CASTEP.Zeitschrift Fuer Kristallographie,2005,220(5/6):567-570. |
| [11] | Kohn W,Shan L.Self-consistent equations including exchange and correlation effects.Phys.Rev.,1965,140(4A):1133-1138. |
| [12] | Vanderbilt D.Soft self-consistent pseudopotentials in a generalized eigenvalue formalism.Phys.Rev.B,1990,41(11):7892-7895. |
| [13] | Perdew J P,Burke K,Ernzerhof M.Generalized gradient approxirnation made simple.Phys.Rev.lett.,1996,77(18):3865-3868. |
| [14] | Monkhorst H J,Pack J D.Special points for Brillouin-zone integrations.Phys.Rev.B,1976,13(12):5188-5192. |
| [15] | Segall M D,Shah R,Pickard C J,et al.Population analysis of plane-wave electronic structure calculations of bulk materials.Phys.Rev.B,1996,54(23):16317-16320. |
| [16] | Vogt T,Reilly J J,Johnson J R,et al.Site preference of cobalt and deurerium in the structure of a complex AB5 alloy electrode.J.Electrochem.Soc,1999,146(1):15-19. |
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