Density functional theory investigations of the structural and electronic properties of Ag2V4O11

Abstract

We present Density Functional Theory (DFT) investigations in the General Gradient Approximation (GGA) of the structural and electronic properties of the Ag${}_{2}$V${}_{4}$O${}_{11}$ (SVO) compound. We carried out a detailed study of the different structures of SVO proposed in the literature, by comparing the results obtained using DFT and the DFT+U approach. We found that two of the proposed structures are equally probable, the third one being unstable. We have obtained detailed information concerning the structural and electronic properties of SVO, including previously non-existent information on one of the SVO structures, considered hypothetical yet probable in the light of experimental facts from analogous compounds. From the analysis of the electronic density of states and of the Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) states, we propose that, during the earlier stage of the reaction of lithium insertion and de-insertion in Li/SVO primary batteries, the reduction of ${\mathrm{V}}^{5+}$ takes place before that of Ag. In addition, our results allow to predict that only one kind of vanadium atom would be firstly reduced.