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.

Multivalent Ion Conduction in Inorganic Solids

“…In lieu of concretely established design principles motivated by experimentally verified structure−property relationships, computational results provide a logical way to filter promising compounds. However, it should be noted that in experimental corroboration of several materials a low NEB-derived E a has not been achieved, 61,139,140 highlighting that other factors, such as sufficient carrier concentration or optimization of the precursor (σ 0 ), are likely to be key to observing high RT conductivity. Additionally, future computational investigations should consider the MN energy of the compound to ensure that a low E a is ideal.…”

Theoretical and Experimental Study of the Structure and Electrochemical Properties of V-Doped TiNb2O7 Anode for Lithium-Ion Batteries

“…The thermodynamics of vanadium doping was evaluated through the energy of vacancy formation and binding energy terms. The vanadium doping was considered as follows: at the first stage, the vacancy formation energy E V for each metal position M1–M5 was evaluated using the following formula: E V = false| italicE normaldefect + italicE normalM − italicE 0 false| where E 0 and E defect are the total energies of the volume structure and the structure with an introduced vacancy, respectively. E M represents the total energy of M atoms (Ti and Nb) in the bulk metal.…”

Magnocolumbites Mg1–xMxNb2O6−δ (x = 0, 0.1, and 0.2; M = Li and Cu) as New Oxygen Ion Conductors: Theoretical Assessment and Experiment

“…The activation energy E a of ionic conductivity generally consists of two terms: the migration energy E m and the vacancy formation energy E v while the importance of E m depends on the material. − We have roughly estimated E v for oxygen sites as follows: ,,− E normalv ( O ) = | E defect + E O 2 2 − E bulk | where E bulk and E defect are the total energies of the bulk structure and the structure with an introduced oxygen vacancy, respectively, and E O2 is the total energy of the O 2 molecule. To calculate E defect , one neutral oxygen atom was removed from the 1 × 2 × 2 supercell and full relaxation of all atomic positions was performed.…”