Computational Search for Novel Zn-Ion Conductors—A Crystallochemical, Bond Valence, and Density Functional Study

Abstract

We present the stepwise computer screening results to identify solids prone to Zn2+-ion conductivity. The rapid geometrical–topological (GT) screening based on Voronoi partition was utilized as the first step for high-throughput analysis of the ICSD. We found that 334 of 782 Zn-/O-containing compounds possess one-dimensional (1D)-, two-dimensional (2D)-, or three-dimensional (3D)-periodic Zn2+-ion migration maps. Among them, 83 compounds were previously unknown as possible Zn2+-ion conductors. We applied bond valence site energy (BVSE) calculations to evaluate the migration energies for the Zn2+-ion conduction and to ensure that this migration barrier was the lowest of all ions in the respective structure. Of the 83 compounds, 27 fulfilled the condition of being solely Zn2+ conductors. For the nine most promising compounds, we used the Nudged Elastic Band (NEB) method within the density functional theory (DFT) approach to verify Zn2+-ion conductivity. This yielded the most interesting candidates (ZnM2O4, M = Fe, Cr, V; ZnP2O6) with migration energies of less than 0.7 eV/ion. Finally, we simulated ionic conductivities within the kinetic Monte Carlo approach, compared the results of different approaches, and commented on the complexity of the promising structures. We conclude with the proposal of Zn-ion all-solid-state battery variants. The list of the novel prospective Zn2+-ion conductors with characteristics was uploaded to our database batterymaterials.info.