Advancing lithium battery safety: Introducing a composite phase change material with anti-leakage and fire-resistant properties

Abstract

The thermal safety of batteries has still existed challenge in energy-storage power stations and electric vehicles. Composite phase change material (CPCM) as a passive cooling system has great potential in the application of controlling an uneven temperature distribution, but its high flammability and susceptibility to leakage severely restrict its widespread adoption, especially in battery packs for electric vehicles and energy storage. Herein, an innovative paraffin/expanded graphite/[Ca(polyethylene glycol)₂]Cl₂ coordination polymer/triphenyl phosphate (TPP)/hexaphenoxycyclotriphosphazene (HPCP) flame retardant multifunctional CPCM (PPCTH) has been introduced and utilized in battery module for thermal management and preventing thermal runaway. PPCTH2 has contained TPP/HPCP with the proportion of 1:1 which provides a multifunctional CPCM with excellent antileakage properties, high thermal conductivity, superior flame-retardant ability, the PPCTH2 exhibits excellent shape stability without collapsing at 200 °C. Moreover, the total heat release and smoke production of PPCTH2 are 108.8 MJ/m² and 8.4 m², respectively. Additionally, the prismatic battery module endowed with PPCTH2 can maintain the maximum temperature below 50 °C and balance the temperature difference within 4.2 °C at a 2 C discharge rate. Thus, the battery module with PPCTH2 can not only improve the temperature consistency even during long cycling processes but also lengthen the temperature rising time and decrease heat accumulation, further suppressing thermal runaway. Overall, this research presents a multifunctional CPCM with high fire resistance and shape stability, which may contribute to the research and design of improved thermal safety for battery packs and energy-storage units.