Investigation of external heating-induced failure propagation behaviors in large-size cell modules with different phase change materials

The effect of phase change material (PCM) on thermal runaway (TR) and failure propagation in cell modules is investigated. Two PCMs, paraffin (PPCM) and graphene-enhanced hybrid (GHPCM) are considered. Each module is composed of three fully charged 50 Ah LiNixCoyMn1-x-yO2/graphite cells isolated by air or PCM. The onset TR times of cell 1 are around 812, 801, and 942 s in modules without PCM, with PPCM and with GHPCM, respectively. The propagation time from cell 1 (cell 2) to cell 2 (cell 3) is reduced (delayed) from 638 s (168 s) in modules without PCM to 394 s (178 s) in GHPCM modules and 536 s (493 s) in PPCM modules. The PPCM module accompanied by a considerable amount of gas can relieve TR propagation because of less heat feedback from the flame, while the GHPCM module is prone to facilitating propagation due to strong heat transfer between adjacent cells. The module without PCM may delay TR propagation owing to limited heat transfer through contact walls. Compared to modules without PCM and with PPCM, the GHPCM module presents a higher maximum surface temperature (885 degrees C) and more heat release (7614 KJ). Finally, residue and physical damage are also examined. (C) 2020 Elsevier Ltd. All rights reserved.