Insight into cation disorder of Li2Fe0.5Mn0.5SiO4

• Published in: Journal of solid state chemistry 2013-04, Vol.200, p.70-75
• Main Authors: Bini, Marcella, Ferrari, Stefania, Capsoni, Doretta, Spreafico, Clelia, Tealdi, Cristina, Mustarelli, Piercarlo
• Format: Article
• Language: English
• Subjects: Applied sciences; Cations; Chemistry; Condensed matter: structure, mechanical and thermal properties; Crystalline state (including molecular motions in solids); Crystallographic aspects of phase transformations; pressure effects; Defects; Direct energy conversion and energy accumulation; Disorders; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Electrochemistry; Electrodes: preparations and properties; Exact sciences and technology; General and physical chemistry; Li2Fe0.5Mn0.5SiO4; Lithium; Lithium batteries; Molecular dynamics; Physics; Rietveld refinement; Static lattice; Structure of solids and liquids; crystallography; Thermal expansion; thermomechanical effects and density; Thermal properties of condensed matter; Thermal properties of crystalline solids; Tuning; X-ray diffraction; X-rays
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2013.01.019

Transition metal lithium orthosilicates are promising cathode materials for lithium-ion batteries. Here we report a combined experimental (in situ X-ray diffraction) and computational (static lattice and molecular dynamics) study of the thermal behavior of the Li2Fe0.5Mn0.5SiO4 orthosilicate from room temperature to 950°C. Our X-ray results showed that Pmnb polymorph is the most stable all over the explored temperature range. A significant cation disorder up to 80%, based on the anti-site defect, was found. The defect concentration depends on the synthesis route and temperature, and is completely reversible after the thermal treatments. Moreover, a careful analysis of the impurity phases allowed us to identify Li2SiO3, Fe3O4 and Li3Fe5O8, the last one never reported before. The minimization of defects by opportunely tuning the synthetic parameters would be of great importance in view of potential applications of these materials in lithium batteries. A combined experimental in situ X-ray diffraction and computational study of the thermal behavior of the Li2Fe0.5Mn0.5SiO4 is reported herein. The anti-site defect does justify the diffraction patterns changes with temperature. [Display omitted] ► Study of the thermal behavior of Li2Fe0.5Mn0.5SiO4. ► The anti-site defect does justify the diffraction patterns changes with temperature. ► The Pmnb polymorph is stable in the investigated temperaturerange.