THE EFFECT OF PRESSURE ON THE MICROSTRUCTURAL BEHAVIOUR ON SnO 2 THIN FILMS DEPOSITED BY RF SPUTTERING

ABSTRACT Tin oxide has multiple technological applications including Li-ion batteries, gas sensors, optoelectronic devices, transparent conductors and solar cells. In this study tin dioxide (SnO 2 ) thin films were deposited on glass substrates by RF sputtering process in the oxygen (O 2 ) and argon (Ar) plasma medium. The deposition of the thin SnO 2 films was carried out by RF sputtering from SnO 2 targets. Before deposition the system was evacuated to 10 -4 torr vacuum level and backfilled with Ar. The deposition of the nano structured thin SnO 2 films have been performed at different gas pressures. The deposition of the SnO 2 was both carried out at different pure argon gas pressures and argon/oxygen mediums with varying oxygen partial pressures. The effect of argon and argon/oxygen partial gas pressures on the grain structure and film thickness were analyzed in the resultant thin films. The deposited thin films both on glass and stainless steel substrates were characterized with scanning electron microscopy (SEM), X-ray diffractometry equipped with multi purpose attachment. The grain size of the deposited layer was determined by X-ray analysis. The Atomic Force Microscopy (AFM) technique was also conducted on the some selected coatings to reveal grain structure and growth behaviors

Towards high cycle stability yolk-shell structured silicon/rGO/MWCNT hybrid composites for Li-ion battery negative electrodes

Owing to the highest known theoretical specific capacity of 4200 mAhg(-1), low lithiation voltage characteristics and natural abundance, silicon is considered as the most promising negative electrode material for lithium ion batteries which has the potential to replace graphite. Although having striking features, massive volumetric expansions leading to mechanical pulverization and unstable solid electrolyte interphase hinder silicon to be practically exploited as negative electrode material. To address this challenge we design a binder-free and freestanding composite electrode structure which contains embedded silicon yolk-shell particles between graphene/multi walled carbon nanotube skeleton as anode for lithium ion batteries. Electrochemical charge/discharge test results showed that composite anodes exhibited 951 m Ahg(-1) of gravimetric capacity after 500 cycles. This remarkable performance could be ascribed to the complementary effect of yolk-shell particles and conductive structure of graphene/carbon nanotube skeleton

Structural and electrochemical characterization of tin based graphene composite anode for li-ion batteries

In this study, ultrasound assisted solution based chemical synthesis method has been developed to synthesize tin based graphene composite electrodes for Li-ion batteries. SnO2 was grown by using SnCl2.2H(2)O precursor material on graphene layers was produced Hummers method by using flake graphite. The composite electrodes were characterized with scanning electron microscopy (SEM), X-ray diffractometer and thermal analysis methods. The produced composite electrodes were connected to CR2016 button cells as anode and carried out charge-discharge and cyclic voltammeter tests. Long cycle life was achieved by growing tin based electrode materials with high performance on graphene layers to overcome volume expansion problem. The electrode prepared one-step synthesized SnO2-graphene nanocomposite has shown 385 mAhg(-1) specific capacity value after 100 cycles