An Investigation of Facile One-Pot Synthesis of Li2FeSiO4/C Composite for Li Ion Batteries

Abstract

Li2FeSiO4 and its carbon composite are prepared by an urea-assisted combustion method. The synthesis has been carried out in different urea concentrations, namely 1 Molar (M), 2 M and 3 M urea in the cost-effective ambient atmospheric condition. The x-ray diffraction analysis confirms the orthorhombic structure of Li2FeSiO4 compounds. The urea-assisted combustion reaction enhanced the phase purity of the compound and prevented the oxidation of ferrous ions in Li2FeSiO4. The x-ray photo electron spectroscopy analysis further confirmed the reduction of Fe3+ concentration in Li2FeSiO4 while adding urea. The Li2FeSiO4 compound formation in the presence of urea occurred at a temperature < 623 K. The one-pot synthesis of Li2FeSiO4/C with the help of starch and urea in ambient atmospheric condition resulted in Li2FeSiO4 with an orthorhombic crystal structure. The carbon coating in an amorphous nature is observed and the lattice dimension values of Li2FeSiO4/C are 6.248 A, 5.330 A, and 5.029 A. The lattice parameter has remained unchanged with carbon addition. The addition of 5% carbon to Li2FeSiO4 improves the electrical conductivity and lithium diffusion coefficient to 7.24 × 10−4 S cm−1 and 5.54 × 10−6 cm2, respectively. The coulombic efficiency and capacity retention after 50 cycles of Li2FeSiO4/C composite are around 83% and 95%, respectively.