Structural and electrical properties of high energy ball-milled LiMnPO4 for solid-state batteries

Single-phase LiMnPO4 powders were successfully synthesized via High-energy ball-milling by mixing the starting materials in High energy ball-miller at 250 rpm for 8 h, then drying the slurry at 100 C° for 12 h. The resulting powder was characterized by thermal analysis (TGA-DTA-DSC) in the range of 30–1000 C° to study the decomposition and mechanism of chemical reaction for the precursors. It was found that the olivine phase began to crystallize at 416 C°. The calcination process was performed at 700 C° for 2 h without following inert gas during the heat treatment process according to what was concluded from the thermal analysis. X-ray diffraction analysis was used to study the phases and structure of the calcined powder, which shows that pure phase LiMnPO4 was obtained. The morphology and particle size of the calcined powder were estimated by field emission scanning electron microscopy (FESEM), and the results showed the homogenous semi-sphere particles with an average size of range 127 nm. FTIR spectroscopy reveals the internal mods vibration of the olivine structure. Electrical properties for the sintered powder were performed in the range of 20Hz-100kHz to study the electrical conductivity, Also the electrical properties were performed by variation of temperature in the range of 300–410 K. The results for the electrical properties showed poor electrical conductivity of LiMnPO4 and also showed that very low variation of conductivity with temperature, NTC behavior, and moderated value of the dielectric constant.