Tuning the thermal conductivity of lithium intercalated graphite through temperature, strain, and interlayer twist angles

Abstract

Lithium-intercalated graphite has drawn much attention due to its enormous potential for application in microelectronic devices and lithium-ion batteries. A deep understanding of the thermal transport processes in lithium-intercalated graphite not only provides effective ways to precisely tune its thermal conductivity but also offers hope for improving thermal management efficiency in devices. In this study, nonequilibrium molecular dynamics (NEMD) simulations were applied to investigate the effects of temperature, strain, and interlayer twist angles on the thermal conductivity of lithium-intercalated graphite (graphite, LiC₆, LiC₁₂, and LiC₁₈). The thermal conductivity tuning mechanisms under different conditions were explained by using the phonon density of states. The results show that increasing temperature leads to a decreasing trend in thermal conductivity. Regarding the impact of strain, the present calculations indicate that both compressive and tensile strains reduce the thermal conductivity of lithium-intercalated graphite. The interlayer twist angle also significantly affects thermal conductivity. The thermal conductivity k is unique for twisting angles between 0° and 30°. For other twist angles, the thermal conductivity follows the symmetric relation k(θ + nπ/6) = k(−θ + nπ/6) for an integer n, since the structure is symmetric for rotations of one graphene plane with respect to the other by 60 degrees. This study helps elucidate the thermal transport mechanisms of lithium-intercalated graphite, providing foundational data and scientific insights for the design and development of graphite-based electronic devices, energy storage systems, and optoelectronic devices.