Impact of Temperature on the Cyclic Aging of NCA Lithium-Ion Cells

Abstract This study investigates how temperature influences the cyclic aging behavior of Nickel−Cobalt−Aluminum (NCA) lithium-ion 18650 cells. Controlled cycling tests were conducted across a temperature range of 10−35 °C, down to an extended cycling depth of approximately 30% state of health (SOH), to quantify the effects of thermal conditions on capacity fade, energy efficiency, and cycle time. The results demonstrate temperature-dependent degradation mechanisms that significantly impact battery longevity, with important implications for electric vehicles and stationary energy storage systems requiring reliable, durable performance. Additionally, an analytical approach is applied to identify the knee point in the aging trajectory, which marks the onset of accelerated degradation. This methodology segments the capacity retention curve into three distinct phases: stabilization, equilibrium, and non-equilibrium. By analyzing the coefficient of determination (R2) values of linear fits over sliding windows, the method robustly detects the transition point between the equilibrium and non-equilibrium phases. The systematic evaluation of capacity loss, energy efficiency, and phase transitions provides critical insights for optimizing battery management systems (BMS) and thermal control strategies in high-performance applications. This work enables engineers to better predict battery aging patterns and design more effective thermal management solutions to extend battery lifespan and improve overall system reliability.