Enhanced flame-retardant phase change materials with good shape stability for thermal management

Abstract

Phase change materials (PCMs) have become pivotal components in many fields such as energy storage, thermal management, and photothermal conversion. However, challenges including leakage, flammability, and low thermal conductivity have impeded their broad application. In this work, a cross-linked solid-solid PCM (SPEG) using polyethylene glycol (PEG) and styrene-maleic anhydride copolymer (SMA) was synthesized. To enhance flame retardancy and thermal conductivity, black phosphorus (BP) and expandable graphite (EG) were introduced into the PCM matrix, yielding the target product (SPEG-BP/EG PCM) with enhanced properties. The analysis demonstrated that the SPEG-BP/EG sample with the ratio BP/EG of 1:1 (SPEG-BP/EG-1) exhibited a notable decrease in peak heat release rate and total heat release by 55.2 % and 13.2 %, respectively, compared to the SPEG sample. Moreover, thermal conductivity was improved from 0.18 W m−1 K−1 (SPEG) to 0.59 W m−1 K−1 for SPEG-BP/EG-1. The inclusion of SMA in crosslinking facilitated the transition of PEG's phase change behavior from solid-liquid to solid-solid, maintaining an enthalpy efficiency of 64.0 %. SPEG-BP/EG-1 exhibited excellent dimensional stability and cycling performance in open heating/cooling cycle tests, remaining chemically stable even after 60 heating/cooling cycles, as confirmed by DSC analysis. Furthermore, thermal management performance was evaluated using an LED light bulb, revealing a notable reduction of 9.4 °C in the maximal working temperature facilitated by SPEG-BP/EG PCM. This work presented a comprehensive strategy to mitigate the challenges of flammability, low thermal conductivity, and leakage associated with conventional PCM (PEG), thereby having great potential in practical applications in thermal management.