Atomic-scale studies of garnet-type Mg3Fe2Si3O12: Defect chemistry, diffusion and dopant properties

Navaratnarajah Kuganathan; Alexander Chroneos

doi:10.1016/j.powera.2020.100016

Atomic-scale studies of garnet-type Mg3Fe2Si3O12: Defect chemistry, diffusion and dopant properties

Navaratnarajah Kuganathan, Alexander Chroneos

Institute for Future Transport and Cities

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Abstract

Materials with low cost, environmentally benign, high structural stability and high Mg content are of considerable interest for the construction of rechargeable Mg-ion batteries. In the present study, atomistic simulations are used to provide insights into defect and diffusion properties of garnet type Mg3Fe2Si3O12. Calculations reveal that the Mg–Fe anti-site defect cluster (0.44 eV/defect) is the lowest energy intrinsic defect process. Three dimensional Mg-ion migration pathway with the activation energy of 2.19 eV suggests that Mg-ion diffusion in this material is slow. Favourable isovalent dopants are found to be Mn2þ, Ga3þ and Ge4þ on the Mg, Fe and Si sites respectively. While the formation of Mg interstitials required for the capacity is facilitated by Al doping on the Si site, Mg
vacancies needed for the vacancy assisted Mg-ion diffusion are enhanced by Ge doping on the Fe site. The electronic structures of favourable dopants are calculated and discussed using density functional theory

Original language	English
Article number	100016
Number of pages	7
Journal	Journal of Power Sources Advances
Volume	3
DOIs	https://doi.org/10.1016/j.powera.2020.100016
Publication status	Published - 30 Jul 2020

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This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).Journal of Power Sources Advances 3 (2020) 100016

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https://www.sciencedirect.com/science/article/pii/S2666248520300160

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title = "Atomic-scale studies of garnet-type Mg3Fe2Si3O12: Defect chemistry, diffusion and dopant properties",

abstract = "Materials with low cost, environmentally benign, high structural stability and high Mg content are of considerable interest for the construction of rechargeable Mg-ion batteries. In the present study, atomistic simulations are used to provide insights into defect and diffusion properties of garnet type Mg3Fe2Si3O12. Calculations reveal that the Mg–Fe anti-site defect cluster (0.44 eV/defect) is the lowest energy intrinsic defect process. Three dimensional Mg-ion migration pathway with the activation energy of 2.19 eV suggests that Mg-ion diffusion in this material is slow. Favourable isovalent dopants are found to be Mn2{\th}, Ga3{\th} and Ge4{\th} on the Mg, Fe and Si sites respectively. While the formation of Mg interstitials required for the capacity is facilitated by Al doping on the Si site, Mgvacancies needed for the vacancy assisted Mg-ion diffusion are enhanced by Ge doping on the Fe site. The electronic structures of favourable dopants are calculated and discussed using density functional theory",

author = "Navaratnarajah Kuganathan and Alexander Chroneos",

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T1 - Atomic-scale studies of garnet-type Mg3Fe2Si3O12: Defect chemistry, diffusion and dopant properties

AU - Kuganathan, Navaratnarajah

AU - Chroneos, Alexander

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PY - 2020/7/30

Y1 - 2020/7/30

N2 - Materials with low cost, environmentally benign, high structural stability and high Mg content are of considerable interest for the construction of rechargeable Mg-ion batteries. In the present study, atomistic simulations are used to provide insights into defect and diffusion properties of garnet type Mg3Fe2Si3O12. Calculations reveal that the Mg–Fe anti-site defect cluster (0.44 eV/defect) is the lowest energy intrinsic defect process. Three dimensional Mg-ion migration pathway with the activation energy of 2.19 eV suggests that Mg-ion diffusion in this material is slow. Favourable isovalent dopants are found to be Mn2þ, Ga3þ and Ge4þ on the Mg, Fe and Si sites respectively. While the formation of Mg interstitials required for the capacity is facilitated by Al doping on the Si site, Mgvacancies needed for the vacancy assisted Mg-ion diffusion are enhanced by Ge doping on the Fe site. The electronic structures of favourable dopants are calculated and discussed using density functional theory

AB - Materials with low cost, environmentally benign, high structural stability and high Mg content are of considerable interest for the construction of rechargeable Mg-ion batteries. In the present study, atomistic simulations are used to provide insights into defect and diffusion properties of garnet type Mg3Fe2Si3O12. Calculations reveal that the Mg–Fe anti-site defect cluster (0.44 eV/defect) is the lowest energy intrinsic defect process. Three dimensional Mg-ion migration pathway with the activation energy of 2.19 eV suggests that Mg-ion diffusion in this material is slow. Favourable isovalent dopants are found to be Mn2þ, Ga3þ and Ge4þ on the Mg, Fe and Si sites respectively. While the formation of Mg interstitials required for the capacity is facilitated by Al doping on the Si site, Mgvacancies needed for the vacancy assisted Mg-ion diffusion are enhanced by Ge doping on the Fe site. The electronic structures of favourable dopants are calculated and discussed using density functional theory

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