Structural, thermodynamic, electronic, and mechenical properties of calcium manganese oxide polymorphs for application as cathode material in calcium ion batteries

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dc.contributor.advisorLethole, N.L.
dc.contributor.authorRoberts, Oswald
dc.date.accessioned2026-09-15T07:44:37Z
dc.date.available2026-09-15T07:44:37Z
dc.date.issued2024-01-01
dc.descriptionMasters dissertation
dc.description.abstractThe exploration of alternative energy storage battery chemistries has become increasingly crucial in recent years, driven by the anticipated depletion of lithium resources and the high costs associated with Li-ion batteries. In response to these challenges, research on the bivalent Ca-ion has gained traction as a promising alternative for developing new rechargeable battery chemistries. Among the various candidates, CaMn2O4 has emerged as a particularly promising option due to its desirable physical and chemical properties. This study employed ab initio computational simulations to investigate the structural, thermodynamic, electronic, and mechanical characteristics of three different polymorphs of CaMn2O4: namely Fd3m CaMn2O4, Pbcm-CaMn2O4, and Pnma-CaMn2O4 under ambient conditions. The density functional theory (DFT) method, implemented in the CASTEP code, was utilized, with the Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA) and Hubbard U-correction for the exchange-correlation functional. The computed structural lattice parameters demonstrated excellent agreement with experimental data, with a percentage difference of less than 5%, validating the methodology employed. The negative enthalpies of formation indicated that all three CaMn2O4 polymorphs are thermodynamically stable and can be feasibly synthesized under ambient conditions. Analysis of the electronic densities of states revealed that Pnma-CaMn2O4 is metallic, while Fd3m-CaMn2O4 behaves as a semiconductor. Furthermore, the projected intercalation potentials suggest that the Ca ion can be reversibly inserted and removed from Mn2O4. Lastly, the values of elastic constants indicated that the Pbcm-CaMn2O4 and Fd3m-CaMn2O4 polymorphs are mechanically stable, meeting the Born stability conditions, while the Pnma-CaMn2O4 may exist only at elevated pressure. This comprehensive study sheds light on the potential of CaMn2O4 as a potential cathode material in rechargeable Ca-ion batteries.
dc.identifier.citationRoberts, O. (2024) Structural, thermodynamic, electronic, and mechanical properties of calcium manganese oxide polymorphs for application as cathode material in calcium ion batteries. MSc (Physics) dissertation. Alice, South Africa: University of Fort Hare.
dc.identifier.urihttp://hdl.handle.net/20.500.11837/5132
dc.language.isoen
dc.publisherUniversity of Fort Hare
dc.subjectThermodynamics
dc.subjectCathodes
dc.subjectManganese oxides
dc.subjectDensity functionals
dc.subjectStructural Properties
dc.titleStructural, thermodynamic, electronic, and mechenical properties of calcium manganese oxide polymorphs for application as cathode material in calcium ion batteries
dc.typeThesis
person.identifier.orcid0000-0002-6032-810X

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