Assessment of Lithium-Ion Battery Degradation in Electric Aircraft Under a Cycle-Progressive Load Profile

The electrification of aviation is a key step toward reducing emissions, yet uncertainties remain surrounding the long-term behavior of electric aircraft batteries. Conventional degradation testing often relies on fixed profiles that fail to capture the relationship between cell aging and auxiliary power demands. To address this gap, this study experimentally introduces a cycle-progressive load profile, which incrementally increases simulated system power demands to reflect the rising demands of aging of batteries on the active battery thermal management system. Representative flight load profiles for an electric conventional takeoff and landing aircraft and an electric vertical takeoff and landing aircraft were generated using the RCAIDE modeling framework and applied to 24 Molicel P30B lithium-ion cells over 1000 flight cycles. Results show that cycle-progressive profiles accelerate degradation compared to fixed profiles, with up to 22.1\\% higher state-of-health loss and distinct shifts in incremental capacity signatures. To extend the work, a physics-based PyBaMM model was optimally parameterized to simulate cycle-progressive behavior and predict end-of-life under replicated mission scenarios. These findings highlight the importance of testing protocols that incorporate the coupled effects of aging and system power demand, hopefully leading to more realistic assessment of battery systems in electric vehicles.