Hierarchical porous carbon fiber felt loaded with polyethylene glycol as hybrid phase change energy storage sheet for temperature-controlled logistics

Temperature-controlled logistics (TCL) is one of the emerging technologies for food, pharmacy and biologics. Phase change materials (PCMs) have the advantages of high energy storage density, high latent heat, and constant temperature during the phase change process. However, volume expansion, leakage, during the phase change process are the main problems hindering the application of PCMs. Powdery porous carriers have been widely used as matrix to encapsulate PCMs, but the powders is hard to be directly used in engineering. In this contribution, a O₂ plasma treated activated carbon fiber felt (PACFF) with hierarchical porous structure of large (∼100 μm), micro (<2 nm) and mesopores (2 nm–50 nm) is used as matrix to encapsulate polyethylene glycol (PEG) to prepare phase change composite sheet. The large pore formatted by the overlap of fibers give PACFF a high loading rate of PEG, and the micropores and mesopores help to encapsulate PEG molecules to overcome the leakage during phase change process. The PACFF gets smooth surface and large mesoporous pore volume than untreated felt with the loading capacity (73.27 %–85.51 %) and the interface between PACFF and PEG was significantly improved. The PACFF/PEG displayed high latent heat (146–180 J g⁻¹) with adjusted temperature range by changing the PEG molecular weight. The hybrid sheet also displayed a good stability under high temperature and thermal cycle (−18–85 °C). The finite element simulation and a demo set-up is used to demonstrate the potential ability for the TCL application of PACFF/PEG.