N-doped porous carbon chain with 3D interconnected network structure to modify expanded graphite for efficient thermal energy storage materials

Abstract

N-doped porous carbon-based material with a 3D interconnected network structure was synthesized by carbonizing the amino-functionalized metal-organic framework (NH2-MOF-5) combined with expanded graphite (EG). NH2-MOF-5 grows in situ between the EG sheet layers by solvent heat method. After 1000 °C carbonization, N-doped porous carbon (NPC) was supported in the pores of EG in the form of a 3D interconnected carbon network. SA/NPC@EG, which anchored stearic acid (SA) in NPC@EG by capillary action, surface tension, and the additional hydrogen bonding between SA molecules and doped nitrogen, forming a shape-stabilized phase change material. The layer structure of EG reduces the interface thermal resistance. NPC serves as a phonon transfer channel to connect the heat transfer between the EG sheets. The ‍results showed that NPC@EG loaded with 85 wt% SA owned excellent thermal conductivity (2.134‍ W∙m−1∙K−1) while retaining sufficient phase change enthalpy (177.7 J∙g−1). SA/NPC@EG exhibited high thermal stability owing to the combined effect of the expanded graphite sheet layer structure and the N-doped porous carbon chain network structure. This material can block and absorb high-energy-density heat flow to meet the stability and reliability requirements of the working environment.