Phosphorus-Nitrogen-Based Flame-Retardant Polyurethane Composite Phase Change Materials for Battery Thermal Safety System

Abstract

In the fields of electric vehicles and energy storage, power battery modules using phase change material (PCM) as a passive thermal management system have a bright future. However, it is still limited by problems like low fireproof property and simple leaking. Herein, a highly flame-retardant form stable Polyethylene glycol (PEG)/ Expanded graphite (EG) and Diphenylmethane diisocyanate (MDI) and Melamine (MA) with 9,10-dihydro-9-oxa-10-phospha-phenanthrene-10-oxide (DOPO) (PMDM) has been successfully prepared and utilized in square battery module. PEG chain segments acting as the soft phase and isocyanate chain segments as the hard phase of the polyurethane network structure, EG as thermal conductivity enhancer has constructed shape-stabilized CPCM with polyurethane structure. The PMDM2 with DOPO and MA in the ratio of 1:2 can maintain stable shape without leakage at 80°C, the extremely thermally conductive channel created by the porous carbon material can greatly increase the heat conductivity. Besides, the flame self-extinguishing time of PMDM2 is controlled within 1 s, and its total heat release (THR) and peak heat release rate (PHRR) have been lowered to 322.8 kW/m2 and 94.3 MJ/m2, respectively. Comparing with the PM-Module and PEA-Module, even at a 2 C discharge rate after ten cycles, the maximum temperature and maximum temperature differential of the battery module with PMDM2 may be regulated between 55°C and 5.5°C without heat accumulation. The battery module with this particular CPCM design can provide an effective method of passive heat management system with these notable performances.

Keywords: Composite phase change material, Flame retardant, Form stable, Synergistic effect, Thermal management