Oriented cellulose scaffold-based carbonized wood-supported phase change materials with stable morphology and high thermal energy conversion efficiency.

Phase change materials are essential for sustainable thermal management, but challenges such as leakage, formability loss, low thermal conductivity, and poor photo-thermal conversion efficiency limit their stability and versatility. Herein, we propose a simple yet effective carbonization strategy that leverages the inherent three-dimensional, oriented, and hierarchical cellulose skeleton of carbonized wood (CW) to support polyethylene glycol (PEG). When the carbonization temperature is 1000 °C and the heating rate is 3-5 °C/min, the CW's maximum specific surface area and average pore diameter reach as high as 598.19 m2/g and 3.25 nm, respectively. Furthermore, the thermal conductivity of the CW-PEG composite phase change energy storage materials (CW-PEG composite PCESMs) increases to 0.434 W/m·K. The CW-PEG composite PCESMs exhibit a melting enthalpy of 130.5 J/g and an energy storage efficiency of 99.8 %. The surface temperature variations captured by the infrared camera during the heating and cooling cycles underscore the outstanding solar energy conversion efficiency of CW-PEG composite PCESMs. Moreover, even after 50 cycles, the phase change enthalpy retains 95 %, highlighting the CW-PEG composite PCESMs promising potential for energy-efficient building materials and cold chain transportation.