Porous diamond Co-MOF and polyethylene glycol composites as form-stable phase change materials for thermal energy storage

Form-stable phase change materials (FSPCMs) have limited applications in the field of thermal energy storage because of their relatively high costs and cumbersome encapsulation technologies. In this study, low-cost FSPCMs were created using a straightforward direct impregnation method by impregnating polyethylene glycol (PEG) into three-dimensional porous diamond cobalt metal organic framework (Co-MOF). The porous CoMOF support material, with many intense H-bonding motifs, has the ability to trap and encapsulate PEG molecules in its crystal lattices, and keeps the form stable of PEG matrix without leakage even at 100 degrees C. Meanwhile, the three-dimensional diamond configuration of the Co-MOF can offer successive heat transfer paths, leading to the FSPCM composite (95.9 wt%) demonstrating high transition enthalpy (203.38 kJ/kg) with astonishing encapsulation efficiency and impregnation ratio of 96.00 % or 97.14 %, respectively. Additionally, FSPCM reveals outstanding high durability with only slight alterations in temperature of phase transition and value of latent heat even after 30 heating/cooling cycles.