Synthesis and Characterization of LiMnPO 4 Cathode Material via Dittmarite-Type NH 4 MnPO 4 · H 2 O as an Intermediate Compound

Dittmarite-type compound NH4MnPO4·H2O was used as a precursor for the synthesis of nanostructured LiMnPO4 phospho-olivine material with spherical-like morphology. NH4MnPO4·H2O intermediate compound was successfully synthesized by a new method based on precipitation technique. LiMnPO4 composite was generated by solid-state reaction of the pre-synthesized compound NH4MnPO4·H2O with lithium chloride LiCl. The dehydration of NH4MnPO4·H2O and NH4MnPO4·H2O+LiCl products was studied by differential thermal analysis/thermogravimetric analysis. Structural and morphological characterization of both NH4MnPO4·H2O and LiMnPO4 was performed by X-ray diffraction analysis, scanning electron microscope, Fourier transform infrared spectroscopy, energy dispersion spectroscopy and Raman spectra analyses. It was found that the morphology and texture of the dittmarite-type precursor results in non-uniform distribution with a preferred orientation along the [0 1 0] direction. Contrariwise, the LMP nanoparticles are packaged together in a compact manner with spherical shape and good distribution, with various sizes in the range of 0.9 ± 0.1 μm.