Modelling Cationic Diffusion in Nickel-Based Honeycomb Layered Tellurates using Vashishta-Rahman Interatomic Potential and Relevant Insights

24 May 2021, Version 4
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

Although the fascinatingly rich crystal chemistry of honeycomb layered oxides has been accredited as the propelling force behind their remarkable electrochemistry, the atomistic mechanisms surrounding their operations remain unexplored. Thus, herein, we present an extensive molecular dynamics study performed systematically using a reliable set of inter-atomic potential parameters of A2Ni2TeO6 (where A = Li, Na, and K). We demonstrate the effectiveness of the Vashishta-Rahman form of the inter-atomic potential in reproducing various structural and transport properties of this promising class of materials and predict an exponential increase in cationic diffusion with larger inter-layer distances. The simulations demonstrate the correlation between broadened inter-layer (inter-slab) distances associated with the larger ionic radii of K and Na compared to Li and the enhanced cationic conduction exhibited in K2Ni2TeO6 and Na2Ni2TeO6 relative to Li2Ni2TeO6. Whence, our findings connect lower potential energy barriers, favourable cationic paths and wider bottleneck size along the cationic diffusion channel within frameworks (comprised of larger mobile cations) to the improved cationic diffusion experimentally observed in honeycomb layered oxides. Furthermore, we elucidate the role of inter-layer distance and cationic size in cationic diffusion. Our theoretical studies reveal the dominance of inter-layer distance over cationic size, a crucial insight into the further performance enhancement of honeycomb layered oxides.

Keywords

Honeycomb Layered Oxides
Energy Storage
High Voltage
Rechargeable Batteries
Ionic Mobility
Molecular Dynamics
Vashishta-Rahman Potential
Interlayer Distance
Tellurates
Transport
Bottleneck radius
Population Density
Anisotropic Diffusion

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