Synthesis, characterization and electrochemical performance of Li$_2$Ni$_x$Fe$_{1−x}$SiO$_4$ cathode materials for lithium ion batteries

[摘要] Li$_2$Ni$_x$Fe$_{1−x}$SiO$_4$ ($x = 0$, 0.2, 0.4, 0.6, 0.8 and 1) samples were prepared by a sol–gel process. The crystalstructure of prepared samples of Li$_2$Ni$_x$Fe$_{1−x}$SiO$_4$ was characterized using an X-ray diffractometer. Different crystallographicparameters such as crystallite size and lattice cell parameters have been calculated. Scanning electron microscopy andFourier transform infrared spectroscopy investigations were carried out, which reveal the morphology and function groupsof the synthesized samples. Furthermore, electrochemical impedance spectra measurements are performed. The obtainedresults indicated that the highest conductivity is achieved for the Li$_2$Ni$_{0.4}$Fe$_{0.6}$SiO$_4$ electrode compound. It was observed that Li–Li$_2$Ni$_{0.4}$Fe$_{0.6}$SiO$_{4}$ battery has initial discharge capacity of 164 mAh g$^{−1}$ at 0.1~$C$ rate. The cycle life performance of all Li$_2$Ni$_x$Fe$_{1−x}$SiO$_4$batteries ranged between 100 and 156 mAh g$^{−1}$ with coulombic efficiency range between 70.9 and 93.9%.

[学科分类] 材料工程

[关键词] Positive electrodes;lithium metal silicates;electrical conductivity;cyclic performance.