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

Abstract

Although\nthe fascinatingly rich crystal chemistry of honeycomb layered oxides has been\naccredited as the propelling force behind their remarkable electrochemistry,\nthe atomistic mechanisms surrounding their operations remain unexplored. Thus,\nherein, we present an extensive molecular dynamics study performed\nsystematically using a refined set of inter-atomic potential parameters of A2Ni2TeO6\n(where A = Li, Na, and K). We\ndemonstrate the effectiveness of the Vashishta-Rahman form of the interatomic\npotential in reproducing various structural and transport properties of this\npromising class of materials and predict an exponential increase in cationic\ndiffusion with larger interlayer distances. The simulations further demonstrate\nthe correlation between broadened inter-layer (inter-slab) distances associated\nwith the larger ionic radii of K and Na compared to Li and the enhanced\ncationic conduction exhibited in K2Ni2TeO6 and\nNa2Ni2TeO6 relative to Li2Ni2TeO6.\nWhence, our findings connect lower\npotential energy barriers, favourable cationic paths and wider bottleneck size\nalong the cationic diffusion channel within frameworks (comprised of larger\nmobile cations) to the improved cationic diffusion experimentally observed in\nhoneycomb layered oxides. Furthermore, we explicitly study the role of\ninter-layer distance and cationic size in cationic diffusion. Our theoretical\nstudies reveal the dominance of inter-layer distance over cationic size, a\ncrucial insight into the further performance enhancement of honeycomb layered\noxides.