Si modified by Zn and Fe as anodes in Si-air batteries with ameliorative properties

Abstract

Si-air batteries have been gradually investigated in recent ten years due to their high theoretical capacity and ideal safety. In this work, to ameliorate the properties of Si-air batteries, models of Si electrodes were doped by Zn and Fe atoms respectively and density functional theory (DFT) calculations were performed. By constructing various models of Si-Zn/SiO2 and Si-Fe/SiO2 interfaces, the adsorption energies of SiO2 units on Zn or Fe-doped Si electrodes were first calculated. Meanwhile, the electrostatic difference potentials (EDP) and electron densities vary apparently across the interfaces. Additionally, the local device density of states (LDDOS) exhibit high intensities in the region of interfaces. Moreover, Zn and Fe dopants would introduce energy levels in the band gap and reduce the band gap of the interfaces according to the device density of state (DDOS) and projected local density of states (PLDOS). Finally, the I-V curves show that the current of the Si/SiO2/Si device can be enhanced by the introduction of Zn and Fe in the Si electrode. This work provides a method of surface modification to ameliorate the properties of Si-air batteries and assists to construct the Si-Zn and Si-Fe composite anodes in air batteries.