Evolving safety challenges of power batteries in service: Insights and strategies

Safety concerns have emerged as the central challenge constraining the widespread adoption of electric vehicles (EVs). During service life of EVs, power batteries undergo dynamic evolution in safety performance that fundamentally governs system reliability. This review concludes the main failure triggers from manufacturing to end-of-life, critically shape battery safety and can ultimately trigger thermal runaway (TR). We identify three dominant pathways of degradation. First, manufacturing defects induce localized current imbalances, internal short circuits (ISCs), and interfacial side reactions. Second, external abuse can directly initiate TR through structural damage. Third, long-term cycling leads to irreversible loss of active material and lithium inventory, progressively undermining thermal stability. The research further delineates two distinct patterns of safety evolution. One pathway involves defect- or abuse-induced ISCs that trigger TR, producing observable temperature spikes within seconds to hours. The other results from cumulative degradation under poor thermal or electrical management, manifesting as measurable capacity decline and resistance increase over days to years. To tackle these challenges, we propose a digital twin–based, multi-level safety perception framework that integrates high-precision sensing, mechanistic modeling, and artificial intelligence algorithms, thereby strengthening safety management. This approach offers insights into safeguarding power batteries across their service life and supports the sustainable and safe utilization of EVs.