One-step construction of novel phase change composites supported by a biomass/MXene gel network for efficient thermal energy storage

Phase change composites with excellent light-to-thermal capacity can enhance the utilization efficiency of solar energy and reduce the energy crisis immensely. Current methods for constructing phase change composites include aerogel-based vacuum impregnation, melt blending, and other complex multi-steps methods, hindering their large-scale practical application in solar thermal storage. Here, we report an ingenious one-step strategy to construct sodium alginate (SA)/MXene-wrapped polyethylene glycol (PEG) crosslinked with calcium ions (Ca2+) to form a gel network, resulting in shape-stable biomass/MXene phase change composites (SMPCCs). The SMPCCs exhibit excellent solar thermal conversion capability and thermal reliability that the temperature will elevate significantly to 75.4 °C in 780 s and storage solar energy as latent heat during illumination. Furthermore, the neglectable decline of thermal energy storage property for the SMPCCs is less than 1% and 2.9% even after 100 cooling-heating and 20 light-thermal cycles, respectively. Thus, this work proposes a simple and effective approach for fabricating biomass-based phase change composites with good shape stability and excellent thermal energy storage performance, which have great potential for solar thermal energy storage applications.