Experimental and Theoretical Study of LiMn2O4 Synthesized by the Solution Combustion Method Using Corn Starch as Fuel
AUTOR(ES)
Siqueira Jr, José M.; Machado, Carolina T.; Quattrociocchi, Daniel S. G.; Garrido, Francisco M. S.; Costa, Leonardo M. da; Ponzio, Eduardo A.; Ferreira, Glaucio B.; Resende, Jackson A. L. C.
FONTE
J. Braz. Chem. Soc.
DATA DE PUBLICAÇÃO
2020-02
RESUMO
Lithium manganese oxide, LiMn2O4, was synthesized in two temperature stages, where the first consisted by an ecofriendly solution combustion method at 300 °C. Finally, the as-burned powders were thermal treated at 500 and 700 °C. The structural and morphological changes were evaluated by the Rietveld method and density functional theory (DFT) calculations. The Rietveld refinement indicates obtaining the spinel cubic phase LiMn2O4 and a small amount of Mn2O3. The analyses by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show a porous microstructure composed of nano-sized crystallites for the sample treated at 500 °C. In cyclic voltammetry, it was possible to observe that the reduction-oxidation reaction is reversible due to the shape of voltammograms and the anodic and cathodic peaks of Mn ions. The theoretical calculations considered the experimental crystallographic parameters. The unit cell volume change was evaluated according to distinct amounts of lithium ions in the structure. The removal of the Li+ cations from the oxides promotes a volume contraction. Therefore, it was possible to evaluate the participation of the Mn3+ ions in the frontier region between the valence and conduction bands. The density of states (DOS) calculation shows a predominant contribution of the O 2p and Mn 3d orbitals in the frontier orbitals.
Documentos Relacionados
- Improvement of electrochemical performance of LiMn2O4 composite cathode by ox-MWCNT addition for Li-ion battery
- Influence of different fuel agents on the combustion synthesis of the nanostructured Li1.05Mn2O4 oxide
- Síntese assistida por microondas de LiMn2O4, caracterização e testes como catodo para dispositivos de armazenamento de energia
- Preparação e caracterização de compósitos de polipirrol (LiMn2O2)/ fibra de carbono para catodos em baterias secundárias.
- Determination of Mn2+ ion by solution scanometry as a new, simple and inexpensive method