Synthesis, Characterization and Electrochemical Properties of Germanium@Multiwalled Carbon Nanotubes Composite As Anode in Lithium Ion Batteries

Abstract

Rechargeable lithium ion batteries have been in use in portable appliances like laptops, cameras and cellular phones due to high gravimetric energy together with long cycle life [1-3]. However, the deployment of lithium ion batteries in applications like hybrid electric vehicles, plug in hybrid electric vehicles and smart grids needs improvements in terms of energy and power densities along with reducing the cost [1-2]. Nanostructured electrode active materials have attracted much attention because of their potential to provide higher energy and power densities than bulk materials. In Particularly anodes such as silicon, germanium, tin, metal oxides and carbonaceous are the most promising materials [2-3]. Germanium (Ge) nanocrystals with size of 5 nm and their composites of multiwalled carbon nanotubes (MWCNTs) were synthesized via solvothermal method. Ge and Ge@MWCNTs have been characterized through X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and Raman spectroscopy. Furthermore, electrochemical studies have been carried out with cyclic voltammetry, galvanostatic charging and discharging test, and impedance spectroscopy. The results show that as prepared Ge-MWCNTs nanocomposite exhibits improved cycling performance with higher capacity retention with respect to pure Ge electrode. In fact, Ge-MWCNTs nanocomposite shown a discharge capacity of 1160 mAh g-1 at current rate of 0.1C after 60 cycles as well as an excellent discharge capacity of 406 mAh g-1 at a current rate of 5C even after 400 cycles.