The widespread use of high-energy–density lithium-ion batteries (LIBs) in new energy vehicles and large-scale energy storage systems has intensified safety concerns, especially regarding the safe and reliable operation of large battery packs composed of hundreds of individual cells. This review begins with an analysis of the causes and failure mechanisms, and then continues with an examination of the many connections and influences among different factors to elucidate the complex and unpredictable issues of LIB safety. The analysis includes examples of large-scale battery failures to illustrate how failures propagate within extensive battery networks, highlighting the unique challenges associated with monitoring the safety of large-scale battery packs. Subsequently, a comparative assessment of numerous detection technologies is further conducted to underscore the challenges encountered in battery safety detection, particularly in large-scale battery systems. Additionally, the paper discusses the role of artificial intelligence (AI) in addressing battery safety concerns, explores the future trajectory of safety detection technology, and outlines the necessity and foundational framework for constructing smart battery management systems (BMSs). The discussion focuses on how AI and smart BMSs can be tailored to manage the complexities of large-scale battery packs, enabling real-time monitoring and predictive maintenance to prevent catastrophic failures.