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 Mg 3Fe 2Si 3O 12. 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 Mn 2+, Ga 3+ and Ge 4+ 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.
Bibliographical noteThis 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
- Atomistic simulation
- Mg Fe Si O
ASJC Scopus subject areas
- Energy Engineering and Power Technology
- Materials Chemistry