Effects of Fe layer on Li insertion/extraction Reactions of Fe/Si Multilayer thin Film Anodes for Lithium Rechargeable Batteries

Abstract

The influences of the thickness and microstructure of Fe layer on the electrochemical performances of Fe/Si multilayer thin film anodes were investigated.The Fe/Si multilayer films were prepared by electron beam evaporation, in which Fe layer was deposited with/without simultaneous bombardment of Ar ion.The kinetics of Li insertion/extraction reactions in the early stage are slowed down with increasing the thickness of Fe layer, but such a slowdown seems to be negligible for thin Fe layers less than about 500 Å.When the Fe layer was deposited with ion bombardment, even the 300 Å thick Fe layer significantly suppress Li diffusion through the Fe layer.This is attributed to the dense microstructure of Fe layer, induced by ion beam assisted deposition (IBAD).It appears that the Fe/Si multilayer films prepared with IBAD show good cyclability compared to the film deposited without IBAD.