Energy Storage Science and Technology ›› 2022, Vol. 11 ›› Issue (5): 1419-1427.doi: 10.19799/j.cnki.2095-4239.2021.0548

• Energy Storage System and Engineering • Previous Articles     Next Articles

Overcharge induced thermal runaway behaviors of pouch-type lithium-ion batteries with LFP and NCM cathodes: the differences and reasons

Lei LI(), Zhao LI, Dan JI, Huichang NIU()   

  1. Guangzhou Institute of Industrial Technology, Guangzhou 511458, Guangdong, China
  • Received:2021-10-19 Revised:2021-10-20 Online:2022-05-05 Published:2022-05-07
  • Contact: Huichang NIU E-mail:lilei@gziit.cn;niuhuichang@ gziit.cn

Abstract:

Compared with hardshell batteries, pouch-type lithium-ion batteries (LIBs) have the qualities of higher energy density, causing unique thermal runaway behaviors and hazards due to their special structures. In this work, two types of LIB variations with lithium iron phosphate (LFP) and lithium nickel cobalt manganese oxide (NCM) based cathodes are experimentally investigated for failure, thermal runaway behaviors, mass loss, rupture voltage, and temperature rise after being over-charged at various current-rates (0.5~3 C). The results show that the aluminum plastic shell ruptures for LFP and NCM LIBs due to pressure accumulation inside due to side reactions during overcharging. Specifically, the LFP battery ruptures and fails when charged to a 133.4% state of charge (SOC), while the NCM battery ruptures after thermal runaway and fires when charged to about 143.8% SOC. With the increase of current rate, the rupture voltage of LIBs firstly increases and then decreases. The rupture voltage is the highest at 1.5 C, and the rupture voltages of LFP batteries are higher than those of the NCM batteries. In addition, the mass loss of LFP and NCM batteries ranges from 2.07% to 5.82% and 28.51% to 36.75%, respectively, independent of the current rate. The various characteristics of temperature rise in LFP and NCM batteries during overcharge are also revealed, and the reasons for this difference are analyzed from the perspective of the molecular structure of cathode materials. The results of this study could provide references for the selection of LIBs for electric vehicles.

Key words: pouch-type lithium-ion batteries, failure, thermal runaway, over-charging, lithium iron phosphate, lithium nickel cobalt manganese oxide

CLC Number: