Synthesis, characterization and electrochemical performance of Li2NixFe1-xSiO4 cathode materials for lithium ion batteries

Abstract

Li2NixFe1-xSiO4 (x = 0, 0.2, 0.4, 0.6, 0.8 and 1) samples were prepared by a sol-gel process. The crystal structure of prepared samples of Li2NixFe1-xSiO4 was characterized using an X-ray diffractometer. Different crystallographic parameters such as crystallite size and lattice cell parameters have been calculated. Scanning electron microscopy and Fourier transform infrared spectroscopy investigations were carried out, which reveal the morphology and function groups of the synthesized samples. Furthermore, electrochemical impedance spectra measurements are performed. The obtained results indicated that the highest conductivity is achieved for the Li2Ni0.4Fe0.6SiO4 electrode compound. It was observed that Li-Li2Ni0.4Fe0.6SiO4 battery has initial discharge capacity of 164 mAh g-1 at 0.1C rate. The cycle life performance of all Li2NixFe1-xSiO4 batteries ranged between 100 and 156 mAh g-1 with coulombic efficiency range between 70.9 and 93.9%.