High-rate properties of Li1.95FeSiO4/C/CNTs composite as cathode material for lithium-ion batteries

Li1.95FeSiO4/C/CNTs, Li2FeSiO4/C/CNTs and Li1.95FeSiO4/C composites were successfully prepared by the means of solid-state reaction in the present work. X-ray diffraction (XRD), scanning electron microscopy (SEM), charge–discharge test and electrochemical impedance spectra measurement were used to characterize the above samples and their differences were comparatively discussed. It was found that the Li1.95FeSiO4/C/CNTs composite delivered the best electrochemical performance in terms of the discharge capacity, cycling stability and rate capability among the above three samples. It exhibited a discharge capacity of 148 mAh g− 1 at 0.2 C and 104 mAh g− 1 at 5 C, respectively, and after 100 cycles at 1 C, 99.2% of its initial capacity was retained. EIS result showed that electrochemical resistance of the Li1.95FeSiO4/C/CNTs electrode was obviously decreased, revealing much faster kinetics in comparison with the Li2FeSiO4/C/CNTs and Li1.95FeSiO4/C electrodes.

► Li1.95FeSiO4/C/CNTs was synthesized by a traditional solid-state reaction method.
► Li1.95FeSiO4/C/CNTs showed high rate capability and excellent cycling stability.
► Incorporation of CNTs is highly beneficial to electronic conductivity.
► Presence of Li vacancies can significantly contribute to ionic conductivity.