Enhanced comprehensive performance of polyethylene glycol based phase change material with hybrid graphene nanomaterials for thermal energy storage

The design and preparation of high comprehensive performance composite phase change materials (PCMs) via a straightforward route were pioneered. Graphene oxide (GO) nanosheets were introduced as supporting materials to keep the shape of polyethylene glycol (PEG) stable during the phase change process and graphene nanoplatelets (GNP) were used as conductive fillers to improve the thermal conductivity and electrical conductivity. The comprehensive performance and structure-property relationships of composite PCMs with hybrid graphene nanomaterials were investigated by means of various characterization techniques. The PEG/GO/GNP composite PCM with only 2 wt% GO and 4 wt% GNP hybrid fillers exhibited superior comprehensive performance: thermal energy storage density as high as 98.2% of pure PEG, shape stabilization effect, high thermal conductivity of 1.72 W/mK (more than 490% increase over pure PEG), high electrical conductivity of 2.5 S/m and excellent thermal reliability after thermal cycling. The incorporated GO and GNP were proved to be effective supporting materials and conductive materials respectively, and also played an important role in improving the phase change enthalpy of PEG. Furthermore, GO also contributed to the enhancement of thermal conductivity but acted as barriers in the conductive path. The present study represents an important step toward developing high comprehensive performance composite PCMs.