Performance study of flexible, flame-retardant, and sustainable energy storage composite phase change materials based on phosphorylated cellulose skeleton

In recent years, with the development of electric vehicles and electric vessels, the issues of battery thermal safety have garnered significant attention. Composite phase-change materials (CPCMs) hold great potential as passive cooling systems in battery thermal management systems (BTMS), but their high flammability remains an unresolved challenge. This study successfully developed a flexible composite phase-change material, CPCM/P-CSF@rGO, by encapsulating a eutectic phase-change material composed of mannitol and galactitol in a three-dimensional hydrogen-bonded network, self-polymerised by phosphated corn straw cellulose (P-CSF) and reduced graphene oxide (rGO). The study demonstrates that the strong hydrogen bonding network formed between the phosphate groups introduced by phosphoric acid modification and rGO constructs highly efficient thermal conduction pathways, achieving a thermal conductivity of 1.039 W/(m•K) and significantly accelerating thermal response rates. Simultaneously, the incorporation of the P-CSF@rGO framework endows the material with excellent flexibility and shape stability. Due to the in-situ flame-retardant modification of the framework, the phase-change material maintains a high latent heat of phase-change (194.7 J/g) and achieves superior flame retardancy through gas-phase and condensation-phase mechanisms. It exhibits a limiting oxygen index of up to 30.64% and rapidly extinguishes itself when exposed to open flame in atmospheric conditions. Thus, the flexible composite phase-change material (CPCM/P-CSF@rGO) supported by a phosphorylated cellulose framework emerges as a promising candidate for ensuring safety and high performance in thermal management applications.