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Doping is one of the most important methods to improve the electronic conductivity and modify its electrochemical performance of LiFePO4. Rare earth elements have become an effective selection for doping modification due to their high electronic charges, large ion radii and strong self-polarization ability. In this work, we study the structural, electronic and ionic diffusion properties of LiFePO4 with rare earth (RE) doping (La, Ce, Pr) by using first-principles calculation based on density functional theory. The calculated results show that the lattice constant and cell volume of LiFePO4 increase to a different degree after RE doping. In the delithiation process, the volume change rate of the material after RE doping is significantly reduced, indicating the cycle performance of the material is improved, on the other hand, the energy density is reduced. The calculated density of states suggests that RE-doped LiFePO4 exhibits metallic characteristics, which is different from the undoped one with semiconductor characteristics. As a result, the RE-doping can increase the electronic conductivity of the material. The calculation of elastic modulus demonstrates the increase of ductility for RE-doped LiFePO4, and it can be predicted that the cycle performance and the rate performance of the RE-doped battery have great improvement. In addition, La and Ce doped LiFePO4 materials exhibit that the complex energy barrier can change during the Li ion migration, and the migration barriers vary considerably, depending on different paths, which is related to the variation of potential energy surface caused by the doping of rare-earth elements. The Li-ions are far from the RE ions, the migration barriers are obviously lower than the undoped one, while the Li-ions are closest to RE ions, the migration barriers increase essentially. Compared with Ce doping, the change of the Li-ion migration barrier caused by La doping is great, indicating that RE ion doping has a greater influence on the local structure of the system.
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Keywords:
- first-principles calculations /
- rare-earth doped /
- lithium-ion battery /
- LiFePO4
[1] Tarascon J M, Armand M 2001 Nature 414 359Google Scholar
[2] Padhi A K, Nanjundawamy K S, Goodenough J B 1997 J. Electrochem. Soc. 144 1188Google Scholar
[3] Scrosati B, Garche J 2010 J. Power Sources 195 2419Google Scholar
[4] Yamada A, Chung S C 2001 J. Electrochem. Soc. 148 A960Google Scholar
[5] Takahashi M, Tobishima S I, Takei K, Sakurai Y 2002 Solid State Ionics 148 283Google Scholar
[6] Yamada A, Chung S C, Hinokuma K 2001 J. Electrochem. Soc. 148 A224Google Scholar
[7] Huang H, Yin S C, Nazar L F 2001 Electrochem. Solid-State Lett. 4 A170Google Scholar
[8] Chung S Y, Bloking J T, Chiang Y M 2002 Nat. Mater. 1 123Google Scholar
[9] Chung S Y, Chiang Y M 2003 Electrochem. Solid-State Lett. 6 A278Google Scholar
[10] Shi S Q, Liu L J, Ouyang C Y, Wang D S, Wang Z X, Chen L Q, Huang X J 2003 Phys. Rev. B 68 195108Google Scholar
[11] Wang Z, Sun S, Xia D, Chu W, Zhang S, Wu Z 2008 J. Phys. Chem. C 112 17450Google Scholar
[12] Thackeray M 2002 Nat. Mater. 1 81Google Scholar
[13] Jiang B Q, Hu S F, Wang M W, Ouyang X P, Gong Z Y 2011 Rare Metals 30 115Google Scholar
[14] Ghosh P, Mahanty S, Basu R N 2009 Electrochim. Acta 54 1654Google Scholar
[15] Sun H B, Chen Y G, Xu C H, Zhu D, Huang L H 2012 J. Solid State Electrochem. 16 1247Google Scholar
[16] Ding Y H, Zhang P, Jiang Y, Gao D H 2007 Solid State Ionics 178 967Google Scholar
[17] 郑路敏, 钟淑英, 徐波, 欧阳楚英 2019 68 138201Google Scholar
Zheng L M, Zhong S Y, Xu B, Ouyang C Y 2019 Acta Phys. Sin. 68 138201Google Scholar
[18] Tian Y W, Kang X X, Liu L Y, Xu C Q, Qu T 2008 J. Rare Earths 26 279Google Scholar
[19] Luo S H, Tian Y, Li H, Shi K J, Tang Z L, Zhang Z T 2010 J. Rare Earths 28 439Google Scholar
[20] Needham S A, Wang G X, Liu H K, Drozd V A, Liu R S 2007 J. Power Sources 174 828Google Scholar
[21] Shi S, Gao J, Liu Y, Zhao Y, Wu Q, Ju W, Ouyang C, Xiao R 2016 Chin. Phys. B 25 018212Google Scholar
[22] Kresse G, Furthmüller J 1996 Phys. Rev. B 54 11169Google Scholar
[23] Blöchl P E 1994 Phys. Rev. B 50 17953Google Scholar
[24] Perdew J P, Chevary J A, Vosko S H, Jackson K A, Pederson M R, Singh D J, Fiolhais C 1992 Phys. Rev. B 46 6671Google Scholar
[25] Anisimov V I, Zaanen J, Andersen O K 1991 Phys. Rev. B 44 943Google Scholar
[26] Zhou F, Kang K, Maxisch T, Ceder G, Morgan D 2004 Solid State Commun. 132 181Google Scholar
[27] Li B, Metiu H 2010 J. Phys. Chem. C 114 12234Google Scholar
[28] Shi S, Tang Y, Ouyang C, Cui L, Xin X, Li P, Zhou W, Zhang H., Lei M, Chen L 2010 J. Phys. Chem. Solids 71 788Google Scholar
[29] Ning F H, Xu B, Shi J, Wu M S, Hu Y Q, Ouyang C Y 2016 J. Phys. Chem. C 120 18428Google Scholar
[30] Monkhorst H J, Pack J D 1976 Phys. Rev. B 13 5188Google Scholar
[31] Henkelman G, Jónsson H 2000 J. Chem. Phys. 113 9978Google Scholar
[32] He B, Chi S T, Ye A J, Mi P H, Zhang L W, Pu B W, Zou Z Y, Ran Y B, Zhao Q, Wang D, Zhang W Q, Zhao J T, Adams S, Avdeev M, Shi S Q 2020 Sci. Data 7 151Google Scholar
[33] Streltsov V A, Belokoneva E L, Tsirelson V G, Hansen N K 1993 Acta Crystallogr., Sect. B 49 147Google Scholar
[34] Xie Y, Yu H T, Yi T F, Zhu Y R 2014 ACS Appl. Mater. Interfaces 6 4033Google Scholar
[35] Andersson A S, Kalska B, Hggstrm L, Thomas J O 2000 Solid State Ionics 130 41Google Scholar
[36] Wang Y, Wang Y, Hosono, E, Wang K Zhou H 2008 Angew. Chem. 47 7461Google Scholar
[37] 张华, 唐元昊, 周薇薇, 李沛娟, 施思齐 2010 59 5135Google Scholar
Zhang H, Tang Y H, Zhou W W, Li P J, Shi S Q 2010 Acta Phys. Sin. 59 5135Google Scholar
[38] Maxisch T, Ceder G 2006 Phys. Rev. B 73 174112Google Scholar
[39] Wu Z, Hao X, Liu X, Meng J 2007 Phys. Rev. B 75 054115Google Scholar
[40] Hill R 1952 Proc. Phys. Soc. 65 349Google Scholar
[41] Caravaca M A, Mino J C, Perez V J, Casali R A, Ponce C A 2009 J. Phys. Condens. Matter 21 015501Google Scholar
[42] Pugh S F 2009 Philos. Mag. 45 823Google Scholar
[43] Zhuang Y, Zou Z Y, Lu B, Li Y J, Wang D, Avdeev M, Shi S Q 2020 Chin. Phys. B 29 068202Google Scholar
[44] Morgan D, Van der Ven A, Ceder G 2004 Electrochem. Solid-State Lett. 7 A30Google Scholar
[45] Ouyang C Y, Shi S Q, Wang Z X, Huang X J, Chen L Q 2004 Phys. Rev. B 69 104303Google Scholar
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表 1 未掺杂与稀土掺杂的LiFePO4的晶格常数和超胞体积
Table 1. Optimized lattice contests and cell volume of LiFePO4 without doping and with rare-earth doping.
表 2 未掺杂LiFePO4中的Fe—O键长和稀土掺杂结构中RE—O键长
Table 2. Bond lengths between Fe atoms and O atoms, rare-earth atoms and O atoms in LiFePO4 without doping and with rare-earth doping structure, respectively.
键型 dM–O (M = Fe, La, Ce)/Å Fe—O 2.225 2.080 2.132 2.268 La—O 2.524 2.401 2.419 2.523 Ce—O 2.455 2.334 2.343 2.471 Pr—O 2.442 2.319 2.331 2.454 表 3 LiFePO4未掺杂及稀土掺杂(RE = La, Ce, Pr)的弹性常数(单位: GPa)
Table 3. Elastic constants (in GPa) of LiFePO4 without doping and with rare earth (RE = La, Ce, Pr) doping.
C11 C22 C33 C44 C55 C66 C12 C23 C13 LiFePO4 138 182 174 41 49 43 67 46 54 Ref. [38] 139 198 173 37 51 48 73 46 53 LiFe0.875La0.125PO4 113 153 142 27 35 35 84 61 65 LiFe0.875Ce0.125PO4 106 169 158 31 33 35 76 19 47 LiFe0.875Pr0.125PO4 119 108 172 35 31 28 66 95 40 表 4 未掺杂与稀土掺杂(RE = La, Ce, Pr)的LiFePO4的体模量(B)、剪切模量(G)、B/G、杨氏模量(E)、泊松比(v)
Table 4. Bulk modulus (B), shear modulus (G), B/G, Young’s modulus (E), Poisson’s ratio (v) for LiFePO4 without doping and with rare earth (RE = La, Ce, Pr) doping.
B/GPa G/GPa B/G E/GPa v LiFePO4 92 48 1.92 122 0.2782 Ref. [38] 94 48 1.92 124 0.2800 LiFe0.875La0.125PO4 91 32 2.87 85 0.3440 LiFe0.875Ce0.125PO4 79 37 2.15 95 0.2987 LiFe0.875Pr0.125PO4 87 29 3.00 78 0.3502 -
[1] Tarascon J M, Armand M 2001 Nature 414 359Google Scholar
[2] Padhi A K, Nanjundawamy K S, Goodenough J B 1997 J. Electrochem. Soc. 144 1188Google Scholar
[3] Scrosati B, Garche J 2010 J. Power Sources 195 2419Google Scholar
[4] Yamada A, Chung S C 2001 J. Electrochem. Soc. 148 A960Google Scholar
[5] Takahashi M, Tobishima S I, Takei K, Sakurai Y 2002 Solid State Ionics 148 283Google Scholar
[6] Yamada A, Chung S C, Hinokuma K 2001 J. Electrochem. Soc. 148 A224Google Scholar
[7] Huang H, Yin S C, Nazar L F 2001 Electrochem. Solid-State Lett. 4 A170Google Scholar
[8] Chung S Y, Bloking J T, Chiang Y M 2002 Nat. Mater. 1 123Google Scholar
[9] Chung S Y, Chiang Y M 2003 Electrochem. Solid-State Lett. 6 A278Google Scholar
[10] Shi S Q, Liu L J, Ouyang C Y, Wang D S, Wang Z X, Chen L Q, Huang X J 2003 Phys. Rev. B 68 195108Google Scholar
[11] Wang Z, Sun S, Xia D, Chu W, Zhang S, Wu Z 2008 J. Phys. Chem. C 112 17450Google Scholar
[12] Thackeray M 2002 Nat. Mater. 1 81Google Scholar
[13] Jiang B Q, Hu S F, Wang M W, Ouyang X P, Gong Z Y 2011 Rare Metals 30 115Google Scholar
[14] Ghosh P, Mahanty S, Basu R N 2009 Electrochim. Acta 54 1654Google Scholar
[15] Sun H B, Chen Y G, Xu C H, Zhu D, Huang L H 2012 J. Solid State Electrochem. 16 1247Google Scholar
[16] Ding Y H, Zhang P, Jiang Y, Gao D H 2007 Solid State Ionics 178 967Google Scholar
[17] 郑路敏, 钟淑英, 徐波, 欧阳楚英 2019 68 138201Google Scholar
Zheng L M, Zhong S Y, Xu B, Ouyang C Y 2019 Acta Phys. Sin. 68 138201Google Scholar
[18] Tian Y W, Kang X X, Liu L Y, Xu C Q, Qu T 2008 J. Rare Earths 26 279Google Scholar
[19] Luo S H, Tian Y, Li H, Shi K J, Tang Z L, Zhang Z T 2010 J. Rare Earths 28 439Google Scholar
[20] Needham S A, Wang G X, Liu H K, Drozd V A, Liu R S 2007 J. Power Sources 174 828Google Scholar
[21] Shi S, Gao J, Liu Y, Zhao Y, Wu Q, Ju W, Ouyang C, Xiao R 2016 Chin. Phys. B 25 018212Google Scholar
[22] Kresse G, Furthmüller J 1996 Phys. Rev. B 54 11169Google Scholar
[23] Blöchl P E 1994 Phys. Rev. B 50 17953Google Scholar
[24] Perdew J P, Chevary J A, Vosko S H, Jackson K A, Pederson M R, Singh D J, Fiolhais C 1992 Phys. Rev. B 46 6671Google Scholar
[25] Anisimov V I, Zaanen J, Andersen O K 1991 Phys. Rev. B 44 943Google Scholar
[26] Zhou F, Kang K, Maxisch T, Ceder G, Morgan D 2004 Solid State Commun. 132 181Google Scholar
[27] Li B, Metiu H 2010 J. Phys. Chem. C 114 12234Google Scholar
[28] Shi S, Tang Y, Ouyang C, Cui L, Xin X, Li P, Zhou W, Zhang H., Lei M, Chen L 2010 J. Phys. Chem. Solids 71 788Google Scholar
[29] Ning F H, Xu B, Shi J, Wu M S, Hu Y Q, Ouyang C Y 2016 J. Phys. Chem. C 120 18428Google Scholar
[30] Monkhorst H J, Pack J D 1976 Phys. Rev. B 13 5188Google Scholar
[31] Henkelman G, Jónsson H 2000 J. Chem. Phys. 113 9978Google Scholar
[32] He B, Chi S T, Ye A J, Mi P H, Zhang L W, Pu B W, Zou Z Y, Ran Y B, Zhao Q, Wang D, Zhang W Q, Zhao J T, Adams S, Avdeev M, Shi S Q 2020 Sci. Data 7 151Google Scholar
[33] Streltsov V A, Belokoneva E L, Tsirelson V G, Hansen N K 1993 Acta Crystallogr., Sect. B 49 147Google Scholar
[34] Xie Y, Yu H T, Yi T F, Zhu Y R 2014 ACS Appl. Mater. Interfaces 6 4033Google Scholar
[35] Andersson A S, Kalska B, Hggstrm L, Thomas J O 2000 Solid State Ionics 130 41Google Scholar
[36] Wang Y, Wang Y, Hosono, E, Wang K Zhou H 2008 Angew. Chem. 47 7461Google Scholar
[37] 张华, 唐元昊, 周薇薇, 李沛娟, 施思齐 2010 59 5135Google Scholar
Zhang H, Tang Y H, Zhou W W, Li P J, Shi S Q 2010 Acta Phys. Sin. 59 5135Google Scholar
[38] Maxisch T, Ceder G 2006 Phys. Rev. B 73 174112Google Scholar
[39] Wu Z, Hao X, Liu X, Meng J 2007 Phys. Rev. B 75 054115Google Scholar
[40] Hill R 1952 Proc. Phys. Soc. 65 349Google Scholar
[41] Caravaca M A, Mino J C, Perez V J, Casali R A, Ponce C A 2009 J. Phys. Condens. Matter 21 015501Google Scholar
[42] Pugh S F 2009 Philos. Mag. 45 823Google Scholar
[43] Zhuang Y, Zou Z Y, Lu B, Li Y J, Wang D, Avdeev M, Shi S Q 2020 Chin. Phys. B 29 068202Google Scholar
[44] Morgan D, Van der Ven A, Ceder G 2004 Electrochem. Solid-State Lett. 7 A30Google Scholar
[45] Ouyang C Y, Shi S Q, Wang Z X, Huang X J, Chen L Q 2004 Phys. Rev. B 69 104303Google Scholar
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