Enhancing safety of electric aircraft Batteries: Degradation and thermal runaway behavior at extreme altitudes

Abstract

The operating performance and thermal safety of lithium-ion batteries (LIBs) in high-altitude scenarios are prime concerns for their reliable applications in various fields. High-altitude environments, characterized by low ambient pressure and temperature, can accelerate LIB degradation and increase the risk of thermal runaway (TR). Unlike previous studies focusing solely on ambient pressure or ambient temperature, this work quantifies their high-altitude coupled effects on the battery performance as well as the TR characteristics. Herein, experiments and simulations are combined to analyze the hybrid pulse charge/discharge behavior, direct current internal resistance (DCIR), over-discharge and recharge/re-discharge performance, and TR characteristics of 26650 NiCoMn LIBs under various ambient pressure and temperature conditions. The results show that low ambient pressure at 20 kPa increases the DCIR of LIB by 7.16 mΩ, raises battery temperature by 4.3 °C, lowers energy efficiency to 92.2 %, and advances TR occurrence with mass loss increasing to 7.5 g. Low ambient temperature at 50 °C causes abrupt changes in battery voltage (up to 6.8009 V during pulse charge and down to 2.0641 V during pulse discharge) and increases the DCIR to 284.8 mΩ. When low ambient pressure and low ambient temperature are combined, energy efficiency decreases to 93.5 % and the peak TR temperature of LIB reduces to 214.2 °C at 20 kPa & −50 °C. The research elucidates the relationship between performance/TR behaviors of LIB and individual/coupled environmental factors, shedding new insights into the operation and safety of LIB in the aviation sector. This facilitates to establishing tailored LIB designs and adaptive thermal management strategies to mitigate failure risks in high-altitude applications.