Probing Phase Formation and Structural Transformations in Sodium Extraction and Insertion of NaFe1−yMnyPO4 through First-Principles Calculations
Manganese (Mn) substitution is a widely explored strategy aimed at sustainably enhancing the energy density of iron (Fe)-based electrode materials by taking advantage of the higher redox potential of the former. However, excessive Mn content can lead to detrimental effects, offsetting the expected i...
| Autores: | , , , , , , |
|---|---|
| Tipo de recurso: | artículo |
| Fecha de publicación: | 2024 |
| País: | España |
| Institución: | Universidad del País Vasco |
| Repositorio: | Addi. Archivo Digital para la Docencia y la Investigación |
| OAI Identifier: | oai:addi.ehu.eus:10810/74980 |
| Acceso en línea: | http://hdl.handle.net/10810/74980 |
| Access Level: | acceso abierto |
| Palabra clave: | positive electrode materials olivine NaFePO4 ion batteries rechargeable lithium phosphate stability mechanism |
| Sumario: | Manganese (Mn) substitution is a widely explored strategy aimed at sustainably enhancing the energy density of iron (Fe)-based electrode materials by taking advantage of the higher redox potential of the former. However, excessive Mn content can lead to detrimental effects, offsetting the expected improvements. In exper- imental studies, triphylite NaFe0.8Mn0.2PO4 has been identified as an optimal composition with enhanced electrochemical performance compared to that of its parent phase NaFePO4. Higher Mn contents result in a loss of capacity and increased voltage hysteresis. In this study, density functional theory (DFT) calculations were employed to investigate the phase stability upon desodiation of Mn-poor and -rich NaxFe1−yMnyPO4 compositions. Our findings reveal distinct stability behaviors in antagonistic systems NaxFe0.75Mn0.25PO4 and NaxFe0.25Mn0.75PO4, where the presence of Na-vacancies and charge orderings appear to influence phase stability. In addition, the number of intermediate phases throughout the desodiation process is identified as a crucial factor in buffering the volume changes. This work sheds light on the superior electrochemical performance of lightly Mn-substituted phases and unveils a key parameter for designing future electrode materials with improved performance. |
|---|