Temperature-dependent lithium diffusion in phographene: Insights from molecular dynamics simulation

Abstract

It is noteworthy to elucidate the underlying atomistic insights of next-generation battery electrode materials to overcome the existing constraints associated with its rapid progress. By employing classical molecular dynamics (MD) simulations, we have studied the temperature dependent structural, thermo-mechanical, and Lithium diffusion properties of α- and β-phographene (PhoG) for Lithium-ion battery (LIB) anode applications. Our results show that at 300K both the PhoGs possess negative thermal expansion coefficient and is expounded as proof of anharmonicity present in it due to the existence of pliable bending modes in the out-of-plane direction. The computed ultrahigh stiffness of PhoG helps to prevent the acute lattice expansion issue upon Li intercalation. The study also brings out that Li atom could freely diffuse on the surface of the PhoGs, and thus a fast Li diffusivity and superior conductivity is observed. The calculated Li diffusion activation energies (<0.20eV) of these membranes are lower than many of the typical for Li-based graphitic anode with a Li diffusion coefficient of 10−10–10−12cm2s−1. In this regard, the excellent structural and thermo-mechanical stability, and low activation energy barrier in PhoGs assures its application as an anode material in high-performance LIBs.