Investigations on The Effect Of Sm3+ Doping on The Electrochemical Performance of The Li2FeSiO4/C Nanocomposite Cathode Material for Lithium Ion Batteries

Abstract

Abstract The Li2FeSiO4 has attracted tremendous attention because of its overwhelming advantages, such as high theoretical capacity 330 mAh/g, low cost of raw materials, excellent safety and environment benignity. However, the practical application of Li2FeSiO4 is hampered by its low electronic conductivity and slow diffusion of Li-ions. A strategy has been made to enhance the electronic conductivity of Li2FeSiO4/C by doping of rare earth elements in Fe sites. In the present work, the pure and Sm3+ doped Li2FeSiO4/C cathode material has been prepared by sol-gel method. The samples have been characterized using XRD, SEM-EDAX and FTIR techniques to investigate the effect of Sm3+ doping on Li2FeSiO4/C.\xa0The pure and Sm3+ doped Li2FeSiO4/C possessed an orthorhombic structure with Pmn21 space group. The conductivity of the sample has been characterized by AC impedance analysis. The Li2Fe0.9Sm0.1SiO4/C sample exhibits an excellent electronic conductivity of 2.346x10-4\xa0Scm-1, which is higher than that of bare Li2FeSiO4/C. The electrochemical Li ion intercalation properties of pure and Sm3+ doped Li2FeSiO4/C in aqueous electrolytes have been carried out by cyclic voltammetry (CV) studies. The rare earth doped material exhibits an excellent electrochemical performance in the aqueous electrolyte including good oxidation/reduction reversibility and cyclability. The improved electrochemical performance is attributed to the enhanced electronic conductivity, better structural stability and higher Li-ion diffusion coefficient of the sample which reveals better ionic mobility inside the Sm3+ doped Li2FeSiO4/C host