Study on the influences of calcination temperature on structure and its electrochemical performance of Li2FeSiO4/C nano cathode for Lithium Ion Batteries

Abstract The Li 2 FeSiO 4 /C nanomaterial has been prepared by sol-gel method. Systematic studies have been carried out to examine the impact of calcination temperature on structure and its electrochemical properties of Li 2 FeSiO 4 /C. The TG/DTA analysis has been used to evaluate the influence of temperature on the pure phase Li 2 FeSiO 4 /C nanocomposites. From the Rietveld refined XRD patterns, it is confirmed that the sample calcined at 700 °C and 850 °C possess orthorhombic ( Pmn 2 1 ) and monoclinic ( P 2 1 / n ) structures without any impurity phases. The SEM micrographs indicated the increase of the grain size with increase in the calcination temperature. The results of electrochemical impedance reveal that the orthorhombic Li 2 FeSiO 4 /C exhibits higher electronic conductivity of 1.29 × 10 −4 Scm −1 , which is far better than other samples. The electrochemical behavior of Li 2 FeSiO 4 /C in aqueous electrolyte has been studied by cyclic voltammetry (CV). The sample prepared at 700 °C exhibited an excellent electrochemical performance in an aqueous electrolyte, in which almost symmetric CV curves are observed after 50 cycles that indicate good redox reversibility and cycling stability. The Li-ion diffusion coefficient of the sample calcined at 700 °C is 6.24 × 10 −12 cm 2 s −1 , revealing a good ionic mobility inside the orthorhombic cage.