Sodium Ion Diffusion and Voltage Trends in Phosphates Na4M3(PO4)2P2O7 (M = Fe, Mn, Co, Ni) for Possible High-Rate Cathodes
| Autor: | Emma Kendrick, M. Saiful Islam, Christopher Eames, Stephen M. Wood |
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| Rok vydání: | 2015 |
| Předmět: |
Chemistry
Sodium Diffusion Doping Inorganic chemistry Analytical chemistry chemistry.chemical_element Energy minimization Cathode Surfaces Coatings and Films Electronic Optical and Magnetic Materials law.invention Molecular dynamics General Energy law Density functional theory Physical and Theoretical Chemistry Voltage |
| Zdroj: | Wood, S M, Eames, C, Kendrick, E & Islam, M S 2015, ' Sodium ion diffusion and voltage trends in phosphates Na 4 M 3 (PO 4 ) 2 P 2 O 7 (M = Fe, Mn, Co, Ni) for possible high-rate cathodes ', Journal of Physical Chemistry C, vol. 119, no. 28, pp. 15935-15941 . https://doi.org/10.1021/acs.jpcc.5b04648 |
| ISSN: | 1932-7455 1932-7447 |
| DOI: | 10.1021/acs.jpcc.5b04648 |
| Popis: | Polyanionic phosphates have the potential to act as low-cost cathodes and stable framework materials for Na ion batteries. The mixed phosphates Na4M3(PO4)2P2O7 (M = Fe, Mn, Co, Ni) are a fascinating new class of materials recently reported to be attractive Na ion cathodes which display low-volume changes upon cycling, indicative of long-lifetime operation. Key issues surrounding intrinsic defects, Na ion migration mechanisms, and voltage trends have been investigated through a combination of atomistic energy minimization, molecular dynamics (MD), and density functional theory simulations. For all compositions, the most energetically favorable defect is calculated to be the Na/M antisite pair. MD simulations suggest Na+ diffusion extends across a 3D network of migration pathways with an activation barrier of 0.20–0.24 eV, and diffusion coefficients (DNa) of 10–10–10–11 cm2 s–1 at 325 K, suggesting good rate capability. The voltage trends indicate that doping the Fe-based cathode with Ni can significantly increase the voltage, and hence the energy density. |
| Databáze: | OpenAIRE |
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