An exfoliated montmorillonite as the nanosheet nucleating agent in the subzero phase change material

Abstract Cold energy storage technologies with phase change materials (PCMs) have received increasing attention, but there is still a great vacancy for PCMs that can be applied below 0 °C due to high supercooling degree of aqueous solution. In this work, the nanosheet dispersion phase change materials (NDPCMs) containing the ethylene glycol (EG) aqueous solution and the modified montmorillonite (MTT) at different mass fractions were prepared, in which the modified MTT prepared by surface modification of zwitterionic surfactant and polymer quaternary ammonium salt under high speed shearing could be steadily dispersed due to the combination of charge and steric effects. And the modified MTT could be used as the nanosheet nucleating agent to effectively suppress the supercooling as well as improve the thermal properties of the PCM. The NDPCM with 0.4 wt% modified MTT had an appropriate phase transition temperature of -5.0 °C, higher latent heat of fusion of 189.96 kJ•kg−1, and there was no supercooling in the test of step cooling curves. Moreover, the NDPCM still showed excellent dispersion stability after 50 thermal cycles. These results indicate that the NDPCM has practical application value in cold energy storage.