Structural characteristics of olivine Li(Mg0.5Ni0.5)PO4 via TEM analysis

Abstract

The structural characteristics of olivine-type lithium orthophosphate Li(Mg0.5Ni0.5)PO4 synthesized via solid-state reaction have been studied using X-ray diffraction, ion beam technique, scanning electron microscopy, infrared spectroscopy, transmission electron microscopy and energy dispersive X-ray analysis. The parent LiNiPO4 compound can be synthesized in olivine structure without any evidence of secondary phases as impurities. The structural quality of the parent LiNiPO4 in the absence of secondary component phases resulted in the formation of hexagonal closed packed structure. The olivine analogue compound containing mixed M (M = Mg, Ni) cations, Li(Mg0.5Ni0.5)PO4 contained Li3PO4 as a second phase upon synthesis, however a carbothermal reduction method produced a single-phase compound. The redox behaviour of carbon-coated Li(Mg0.5Ni0.5)PO4 cathode in aqueous lithium hydroxide as the electrolyte showed reversible lithium intercalation. © 2020 Springer Nature Switzerland AG.