Cotton cloth-derived porous carbon skeleton with graphite layer for enhancing the thermal conductivity of energy storage phase change materials

Phase change materials (PCMs) have advantageous energy storage capacity, but their poor shape stability and low thermal conductivity restrict their practical applications in the field of energy storage. In this study, the graphite flakes were adhered to the waste cotton strips, and the cotton strips were rolled up layer by layer to form a cotton-derived porous carbon skeleton after a high temperature carbonization. The graphite flake and the carbonized cotton cloth were connected to each other to forming a good heat conduction path. Composite phase change materials (CPCMs) were successfully prepared by vacuum impregnation of phase change material stearic acid (SA). The results showed that the thermal conductivity of CPCMs can be greatly improved in terms of forming the cotton-derived porous carbon skeleton. When the content of skeleton filler was 26.46 wt%, the normal thermal conductivity of the prepared CPCMs reached 5.51 W/(m·K), which was 21.19 times higher than that of pure stearic acid, along with a photothermal conversion efficiency of 82.6 % and phase change enthalpy of 148.99 J/g. Moreover, the CPCMs demonstrated great shape stability, obvious anti-leakage characteristic and advanced photothermal conversion capacity. The above results show that the CPCMs prepared by this method have broad application prospects in the field of solar thermal storage and thermal management.