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The first-principles plane-wave pseudopotential method based on the density functional theory is used to investigate the mechanism of the influence of interaction between interstitial H atom defect and doped atom on the dehydrogenation performance of LiNH2. We obtain the most stable structure of LiNH2 by geometrical optimization, and calculate the binding-energies, interstitial H atom defect formation energies, densities of states (DOSs), and electric charge populations for LiNH2 and doped LiNH2. Studies show that the results of binding-energy cannot reflect the dehydrogenating properties of LiNH2 and doped LiNH2. In equilibrium, there are a number of interstitial H atom defects; the formation energy of interstitial H atom defect is reduced by doping Mg and Ti, which increases the concentration of interstitial H atoms. Interstitial H atoms can induce the defect energy level in the gap, which reduces the width of the gap, and improves the dehydrogenation performance of LiNH2. The strength of N-H bond in [NH2]- is weakened by interstitial H atom, so that hydrogen atoms in LiNH2 is relatively easy to release. The covalent bond between interstitial H atom and N atom of [NH2]- explains the escape of NH3 from the dehydrogenation reaction of LiNH2 system. The strengths of N-H bonds are not equal in doped LiNH2, a part of N-H bonds are weaker, and other N-H bonds are strong, the hydrogen atoms are easy to release from weaker N-H bonds.
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Keywords:
- hydrogen storage materials /
- first-principles calculation /
- defect /
- dehydrogenation mechanics
[1] Lei Y Q 2000 New Energy Materials(Tianjin:Tianjin University Press)p28 (in Chinese) [雷永泉 2000 新能源材料 (天津:天津大学出版社) 第28页]
[2] Schlapbach L, Zttel A 2001 Nature 414 353
[3] [4] Li S M, Huang Z P 1996 Vacuum and Cryogenics 2 149 (in Chinese) [李式模、黄忠平 1996 真空与低温 2 149]
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[8] Song Y, Guo Z X 2006 Phys.Rev.B 74 195120
[9] [10] Zhang H, Qi K Z, Zhang G Y, Wu D, Zhu S L 2009 Acta Phys. Sin.58 8077 (in Chinese) [张 辉、戚克振、张国英、吴 迪、朱圣龙 2009 物理学报 58 8077]
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[18] [19] Vanderbilt D 1990 Phys.Rev.B 41 7892
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[22] [23] Fang J X, Lu D 1980 Solid State Physics (Shanghai: Shanghai Scientific and Technology Press) p81 (in Chinese) [方俊鑫、陆 栋 1980 固体物理学(上海:上海科学技术出版社)第81页]
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[26] [27] Zhang H, Liu G L, Qi K Z, Zhang G Y, Xiao M Z, Zhu S L 2009 Chin.Phys.B 18 048601
[28] [29] Ichikawa T, Hanada N, Isobe S, Leng H, Fujii H 2004 Phys.Chem. B 108 7887
[30] [31] Wang J, Wang G, Zhao J 2002 Phys.Rev.B 66 035418
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[1] Lei Y Q 2000 New Energy Materials(Tianjin:Tianjin University Press)p28 (in Chinese) [雷永泉 2000 新能源材料 (天津:天津大学出版社) 第28页]
[2] Schlapbach L, Zttel A 2001 Nature 414 353
[3] [4] Li S M, Huang Z P 1996 Vacuum and Cryogenics 2 149 (in Chinese) [李式模、黄忠平 1996 真空与低温 2 149]
[5] [6] [7] Fang S S, Dong Y D 2001 Nature 23 259 (in Chinese) [方守狮、董远达 2001 自然杂志 23 259]
[8] Song Y, Guo Z X 2006 Phys.Rev.B 74 195120
[9] [10] Zhang H, Qi K Z, Zhang G Y, Wu D, Zhu S L 2009 Acta Phys. Sin.58 8077 (in Chinese) [张 辉、戚克振、张国英、吴 迪、朱圣龙 2009 物理学报 58 8077]
[11] [12] [13] Segall M D, Lindan P J D, Probert M J, Pickard C J, Hasnip P J, Clark S J, Payne M C 2002 Phys. Condens. Matter 14 2717
[14] Perdew J P, Wang Y 1992 Phys.Rev. B 45 132441
[15] [16] [17] Hammer B, Hansen L B, Norskov J K 1999 Phys.Rev.B 59 7413
[18] [19] Vanderbilt D 1990 Phys.Rev.B 41 7892
[20] [21] Perdew J P, Wang Y 1992 Phys.Rev.B 46 6671
[22] [23] Fang J X, Lu D 1980 Solid State Physics (Shanghai: Shanghai Scientific and Technology Press) p81 (in Chinese) [方俊鑫、陆 栋 1980 固体物理学(上海:上海科学技术出版社)第81页]
[24] [25] Chen L J, Hou Z F, Zhu Z Z, Yang Y 2003 Acta Phys.Sin.52 2230 (in Chinese) [陈丽娟、侯柱锋、朱梓忠、杨 勇 2003 物理学报 52 2230]
[26] [27] Zhang H, Liu G L, Qi K Z, Zhang G Y, Xiao M Z, Zhu S L 2009 Chin.Phys.B 18 048601
[28] [29] Ichikawa T, Hanada N, Isobe S, Leng H, Fujii H 2004 Phys.Chem. B 108 7887
[30] [31] Wang J, Wang G, Zhao J 2002 Phys.Rev.B 66 035418
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