Constructing a microencapsulated phase change material with leakage resistance, enhanced thermal conductivity, and flame retardancy: Applications in lithium-ion battery thermal safety

A novel microencapsulated PCM (OADP/PG) was constructed. • Excellent thermal conductivity, leakage resistance, and flame retardancy were acquired. • OADP/PG exhibits excellent LIB cooling efficiency. • OADP/PG effectively suppresses the thermal runaway initiation and propagation. Leveraging highly efficient and reversible thermal energy storage and release, phase change materials (PCMs) show immense potential in advanced thermal management. However, the leakage issues, low thermal conductivity, and flammability of organic PCMs severely limit their applications in lithium-ion battery (LIB) thermal management. This work reports the synthesis of a novel microencapsulated PCM (MPCM, OADP/PG), which consists of a polyethylene glycol-modified graphite composite (PEG-g-Graphite, shell) and an intrinsically flame-retardant PCM (OADP, core). With 20 wt% PEG-g-Graphite, OADP/PG20 achieves a thermal conductivity of 0.60 W m −1 K −1 , 130.8% higher than that of OADP, and its leakage ratio is only 1.3% at 65 °C. In the candle ignition test, OADP/PG20 exhibits rapid self-extinguishing behavior within 25 s. In addition, under 5 C charge-discharge conditions, OADP/PG20 reduces the maximum surface temperature of the LIB by 10.8 °C. In the LIB thermal runaway (TR) test, OADP/PG20 significantly delays the onset of TR. It also reduces the peak temperature and suppresses the TR propagation. This work develops an advanced MPCM integrating superior thermal conductivity, leakage resistance, latent heat storage, and flame retardancy. It provides a potential material solution for thermal safety management in LIBs. Download: Download high-res image (201KB) Download: Download full-size image