Germanium-modified silicon as anodes in Si–Ge air batteries with enhanced properties

Abstract

In this study, the effects of Ge modification of Si anodes in Si–Ge air batteries were investigated by building various atomic models of Si/Ge/GeO2 interfaces and performing density functional theory calculations. The results showed that the surface passivation could be restrained effectively by Ge modification because the adsorption energies of the GeO2 units on the Si–Ge anode increased when more Si atoms were substituted by Ge atoms. The electrostatic difference potentials, electron densities, and projected local density of states were also calculated for various Si/Ge/GeO2 interfaces to determine the differences in the properties of the Si-air battery and Si–Ge air battery. In addition, the I–V curves showed that the Si/Ge/SiO2/Si devices had higher currents than the Si/SiO2/Si device and the currents could be modulated by modification with Ge atoms. These findings provide insights into the mechanism responsible for the enhanced properties obtained by modification with Ge and they may facilitate the design of Si–Ge composite anodes for use in air batteries.