High thermal conductivity Zn2+ metal–organic framework based composite phase change materials for battery thermal management

Composite phase change materials (CPCMs) face challenges such as leakage and low thermal conductivity, which considerably limit their widespread application. To address these issues, an innovative CPCM composed of polyethylene glycol (PEG), Zn 2+ metal–organic framework (MOF@Zn 2+ ), and expanded graphite (EG) was proposed and prepared using in situ synthesis and physical mixing. This simple synthesis method eliminates the need for harsh preparation conditions, such as high temperatures, high pressures, or specific catalysts. MOF@Zn 2+ was designed by optimizing the citric acid monohydrate (CAM): zinc acetate dihydrate (ZAD) molar ratio at 3:2, with NaOH providing the necessary alkaline chelating environment. The synergistic effects of MOF@Zn 2+ and EG enable the double optimization of thermal conductivity and antileakage performance. The thermal conductivity of PEG/CAM/ZAD/EG (PCZE4) was reached to 4.32 W/mK that contained citric acid monohydrate (CAM) and zinc acetate dihydrate (ZAD) with 3:2, which was 12 times higher than pure PEG (0.33 W/mK). After heating at 90 °C for 4 h, the PCZE4 retained 98.38 % of its mass. The results reveals that PEG-based CPCM achieves an optimal balance between high thermal conductivity, thermal stability, and latent heat. The heat storage capacity is reflected in the enthalpy of melting (114.24 J/g) and crystallization (102.88 J/g). The proposed CPCM design offers promising insights into passive thermal management systems and energy storage applications.