Thermodynamic coupling in micro-nanocavity graphene/paraffin phase change energy storage materials under impact loading

Abstract

Micro-nanocavity graphene/paraffin nanocomposites (MNGPNs) are emerging as promising phase change materials for passive thermal management in electronics, utilizing the superior thermal conductivity of graphene in conjunction with the excellent heat storage capacity of paraffin. However, current assessments of MNGPNs thermal management performance are primarily conducted under laboratory static conditions, which do not fully represent the complex overload environments encountered in practical applications. In this study, we conducted strain freezing experiments using a split Hopkinson pressure bar and performed recovery analysis to investigate the influence of dynamic loading on thermal behavior through postmortem microstructural characterizations. Our findings reveal significant thermodynamic coupling effects in the in-plane direction, while coupling effects in the out-of-plane direction were less apparent. Specifically, the increase in internal thermal resistance under impact loading, due to the cracking, shedding, and directional changes in the graphene structure, diminishes the heat transfer capacity of MNGPNs in the in-plane direction. Alternations in interfacial thermal resistance caused by the layer compression and shedding affect the out-of-plane heat transfer capacity. Furthermore, the thermal behavior of MNGPNs was validated through heat dissipation experiments. This work provides valuable insights for the practical thermal management applications of MNGPNs, highlighting their performance from a dynamic perspective.