Impact of low temperature exposure on lithium-ion batteries: A multi-scale study of performance degradation, predictive signals and underlying mechanisms

Abstract

The rapid global expansion of electric vehicles and energy storage industries necessitates understanding lithium-ion battery performance under unconventional conditions, such as low temperature. This study investigates long-term capacity degradation of lithium-ion batteries after low temperature exposure subjected to various C-rate cycles. Findings reveal that low temperature exposure accelerates capacity degradation, especially with increased C-rates or longer exposure durations. A distinctive sunken region appears on the NMC H-stage peak as cycling progresses after low temperature exposure, indicating NMC particle damage and serving as a predictive signal for identifying low temperature exposure batteries. Electrochemical analyses and invasive detection indicate that low temperature exposure causes NMC particle cracking, leading to dead lithium generation. This dead lithium deposits on electrode surfaces, as well as the overconsumption of electrolyte, inhibiting reactions and reducing capacity. Additionally, dead lithium accumulates on separators, impeding ion transport and further accelerating capacity loss. NMC particle cracks develop faster after low temperature exposure due to stress concentration at internal slits. This stress concentration causes the maximum stress within the NMC particles to exceed tensile stress limits, resulting in rapid crack propagation. The internal cracks become larger with prolonged low temperature exposure, causing greater stress concentration and leading to faster crack propagation. Based on these insights, strategies from existing literature are discussed to mitigate the adverse impacts of low temperature exposure on lithium-ion battery performance and enhance the reliability and longevity of lithium-ion battery in extreme conditions.