Emerging PEG/VO2 dual phase change materials for thermal energy storage

Abstract

Emerging PEG/VO 2 dual phase change materials (PCM) with phase transition temperature gradients were prepared with polyethylene glycol (PEG) and vanadium dioxide (VO 2 ) through the vacuum impregnation method. To improve the stability, thermal conductivity, and thermal storage capacity of PEG/VO 2 , expanded graphite (EG) with different mass gradients was introduced. PEG was successfully confined as 54.48, 63.91, and 74.31 wt% in the dual composite phase change materials including 2.60, 3.28, and 3.32 wt% EG, respectively. The chemical composition and microstructure characteristics of the composite phase change material were measured by XRD, FTIR, and SEM. The thermal storage capacity of 70–113 J g −1 and phase transition temperature range of 30–70 °C for PEG/VO 2 /EG were determined by DSC. Moreover, compared with pure PEG, the thermal conductivity of PEG/VO 2 /EG 0.10 was increased by up to 93.75%, and the thermal storage capacity was increased by up to 59.35% compared with PEG/VO 2 . Compared to pure PCM, due to the improvement of thermal conductivity, the response to ambient temperature was also significantly shortened. The thermal cycling stability and thermal durability were demonstrated by the thermal cycle test and TG. Besides, PEG/VO 2 /EG 0.10 was used to simulate the thermal management of lithium-ion battery, indicating that the material had certain advantages in cooling and could improve the safety of the battery during use. PEG/VO 2 /EG 0.10 has good application potential in the field of thermal management due to the unique dual phase transition interval. • Dual phase change materials with phase change temperature gradient were successfully prepared. • The thermal conductivity of PEG/VO 2 /EG 0.10 was increased by 93.75% compared PEG and achieves a rapid heat transfer rate. • The simulated thermal management experiments of PEG/VO 2 /EG 0.10 demonstrated excellent performance.