Development of hierarchical MOF-based composite phase change materials with enhanced latent heat storage for low-temperature battery thermal optimization

Abstract

Most of the composite phase change materials (PCMs) based on metal-organic frameworks (MOFs) have much lower latent heat than pure PCMs due to nanoconfined effects, which limits their application in the field of battery insulation. In this work, a series of hierarchical porous carbon nanotubes (CNT)/MOF-199 were synthesized by adjusting the content of N-methyl pyrrolidone (NMP) in the solvent components, and scattered in stearic acid (SA) to obtain a novel composite PCM. The results show that there is a nearly linear relationship between the impregnation ratio, crystallization fraction and impregnation efficiency of PCMs and the mesoporous content of the supporting materials at the maximum loading rate of 70 wt%, which may provide an idea for selecting MOFs supporting materials for PCMs. The latent heat of SA/CNT/MOF-199-2 (SA/CM-2) composite PCM is 97.1/96.2 J·g−1, with a heat loss percentage of only 0.96%. Furthermore, when the lithium-ion battery is discharged 2C at −20 °C, SA/CM-2 used as insulation material can increase the discharge energy by 8.27%. Accordingly, this novel composite PCMs would be hopefully applied to thermal optimization of batteries at low temperatures.