DFT simulation of NaFeSnO4 structure, electronic and electrochemical properties validated by experimental results

[Display omitted] •Geometric and electronic structure and electrochemical properties of NaFeSnO4 have been studied to estimate its feasibility as an anode material in SIB application.•The crystal structure with the atomic sequence ---Fe-Sn-Fe-Sn--- (model-2) is found to be more stable with lower energy in comparison to the atomic sequence ---Fe-Fe-Sn-Sn--- (model-1).•Experimentally measured band gap (2.04 eV) is found to be closely matching with simulated band gap (1.966 eV) obtained using model-2.•Electrochemical properties, calculated assuming conversion followed by alloying-dealloying reaction, suggested presence of voltage plateau at 1.01 V and 0.21 V respectively.•Calculation suggests that NaFeSnO4 exhibits anode action with estimated capacity ~847 mAhg−1 arising predominantly via alloying-dealloying mechanism. We report, for the first time, DFT simulation analysis for structure, electronic and electrochemical properties of NaFeSnO4 considering two distinct models to predict energetically favourable and stable structure followed by its validation with real time experimental results. Mixed cation occupancy at 4c site comprising Fe and Sn atoms in 50:50 ratio, observed in experimental structure, has been modelled considering alternate stacks of SnO6 and FeO6 bi-octahedra in corner sharing arrangement with identical bi-octahedra, forming a zig-zag polyhedral network in model-1. In contrast, model-2 structure comprised an edge shared FeO6 and SnO6 octahedra in corner sharing arrangement with identical FeO6-SnO6 bi-octahedra forming zig-zag polyhedral network. A comparative simulation analysis indicated Model-2 structure energetically favourable than model-1 that agreed well, within error limits, with experimental results on structure and magnetic order. The assumed anti-ferromagnetic coupling between nearest neighbour Fe atoms as input in simulation was confirmed in magnetic hysteresis results validating simulation assumption. Simulation of electronic structure indicated semiconducting electronic property with estimated band gap ~1.966 eV that agrees well with experimental band gap of 2.04 eV obtained using UV–visible spectroscopy. Electrochemical properties, calculated assuming conversion followed by alloying-dealloying reaction, suggested presence of voltage plateau at 0.21 V with redox capacity ~847 mAhg−1. Despite challenges, NaFeSnO4 seems to be promising anode for sodium ion battery.