Novel design and fabrication of form-stable cellulose nanofiber-based phase change composites via click chemistry, coordination reaction, and solvent exchange

Phase change materials (PCMs) show great promise for thermal energy storage and management owing to their high storage capability and stable working temperature. Developing form-stable phase change composites (PCCs) is an effective approach to addressing the liquid leakage problem. However, conventional fabrication methods of incorporating PCMs into three-dimensional crosslinking networks generally involve freeze-drying and vacuum impregnation, which leads to high energy consumption and complicated procedure. Here, we design a novel strategy to rapidly synthesize form-stable PCCs supported by a cellulose nanofiber (CNF)-based skeleton, which combines a series of reactions and methods including click chemistry, coordination reactions, and solvent exchange. The synthesis mechanisms are revealed by adequate characterizations. Based on the facile fabrication strategy, excellent comprehensive performance such as desirable phase change enthalpy, high enthalpy efficiency, superb mechanical and thermal stability, outstanding cycle stability, and mitigated supercooling is realized. Besides, we discover that introducing expanded graphite into the CNF-based matrix could extend the applicability of the strategy from hydrophilic PCMs to hydrophobic PCMs due to repulsion mitigation between the matrix and PCMs, and considerably enhance the thermal conductivity of the PCCs simultaneously. This work achieves a breakthrough in rapidly and effectively fabricating high-performance form-stable PCCs.