Thermal Degradation and Safety Assessment of Li-Ion Battery Cells in Harsh Climates

The performance, safety, and service life of lithium-ion batteries are highly sensitive to temperature, especially under prolonged storage conditions. In this work, four commercially available 18650 lithium-ion cells from different manufacturers were subjected to calendar aging for six months at three temperatures (25°C, 45°C, and 55°C) under both charged and discharged conditions. The objective was to evaluate the impact of temperature and state of charge on capacity fade and overall battery health. The experimental results indicate a clear dependence on aging behavior on both cell chemistry and thermal conditions. All cells exhibited increased capacity loss and degradation in state of health at elevated temperatures, with the most severe fading observed at 55°C. These findings underscore the crucial role of thermal stress in accelerating aging mechanisms, underscoring the importance of effective temperature control in battery system design, particularly for applications in high-temperature environments.