Electrochemical properties of Li2FeSiO4/C nanocomposites prepared by sol-gel and hydrothermal methods

Li$_{2}$FeSiO$_{4}$ is considered as potential cathode material for next generation lithium ion batteries because of its high specific theoretical capacity, low cost, and safety. However, it suffers from poor electronic conductivity and slow lithium ion diffusion in the solid phase. To address these issues, we have studied mesoporous Li$_{2}$FeSiO$_{4}$/C composites synthesized by sol-gel (SG) and hydrothermal (HT) methods using tri-block copolymer (P123) as carbon source and structure directing agent. The structure and morphology of the composites were characterized by XRD, SEM and TEM and the surface area and pore size distribution were measured by using N$_{2}$ adsorption/desorption. Galvanostatic cycling, electrochemical impedance spectroscopy, and cyclic voltammetry were used to evaluate the electrochemical performance of the Li$_{2}$FeSiO$_{4}$/C composites. The Li$_{2}$FeSiO$_{4}$/C (HT) composites show a superior electrochemical performance compared to Li$_{2}$FeSiO$_{4}$/C (SG). At C/30 rate, the discharge capacity of Li$_{2}$FeSiO$_{4}$/C (HT) reached \textasciitilde 276 mAh/g in the 1.5-4.6 V window and shows better rate capability and stability at high rates. We attribute the improved electrochemical performance of Li$_{2}$FeSiO$_{4}$/C (HT) to its large surface area and reduced particle size. The details of the study will be presented.