Facile synthesis of SnO2@carbon nanocomposites for lithium-ion batteries

Abstract

SnO₂@C nanocomposites were synthesized using a citrate gel method in one step. Carbon has been used to increase the conductivity of pristine SnO₂. The SnO₂@C nanocomposites show nanoparticles sized in the range of 30–50 nm. A structural study by XRD shows the tetragonal rutile structure of SnO₂. Furthermore, X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy confirm the existence of SnO₂ along with carbon. The electrochemical performance was investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge–discharge measurements. The nanocomposite has been used as an anode material for lithium-ion batteries. Pristine SnO₂ exhibited a discharge capacity of 1854 mA h g⁻¹ and a corresponding charge capacity of 1038 mA h g⁻¹ for the first cycle. The SnO₂@C nanocomposite showed a discharge capacity of 2574 mA h g⁻¹ and charge capacity of 1481 mA h g⁻¹ for the first cycle. These results clearly show the effect of carbon incorporation in SnO₂. Furthermore, the nanocomposite shows a discharge capacity as high as 725 mA h g⁻¹ after 200 cycles at a current density of 50 mA g⁻¹. Thus, the obtained capacity for the nanocomposites is much higher as compared to that for pristine SnO₂, i.e., 119 mA h g⁻¹ at 50 mA g⁻¹ after 200 cycles. The higher capacity in the nanocomposites is due to the fast transport of electrons and easy transport of lithium ions due to the carbon in the nanocomposites. The SnO₂@C nanocomposite anode exhibits superior cycling stability and rate capability due to its stable electrode structure.