Internal short circuits in lithium-ion batteries: Triggering mechanisms, evolution patterns, reconstruction methods, and safety strategies

Lithium-ion batteries (LIBs) are characterized by high energy density, long cycle life, and low self-discharge rate, making them increasingly prominent in the global energy transition. However, safety concerns remain a critical challenge hindering their large-scale application. Among these issues, the internal short circuit (ISC) stands out as a key factor degrading safety performance and even triggering thermal runaway (TR), necessitating systematic and in-depth research. This paper comprehensively reviews recent advances in the triggering mechanisms, evolution characteristics, and experimental reconstruction methods of ISC in LIBs. First, the triggering mechanisms of ISC are systematically categorized from four dimensions: manufacturing defects, mechanical abuse, electrical abuse, and thermal abuse. Differences in triggering behaviors under various mechanical loading modes are highlighted, and distinct ISC paths resulting from the evolution of the solid electrolyte interphase (SEI) under moderate and extreme high-temperature conditions are revealed. Second, the types and characteristics of ISC are summarized, and two typical evolution modes are proposed based on the correlation among voltage, temperature, and mechanistic features. Third, existing ISC reconstruction methods are classified and compared using a five-dimensional evaluation framework, with their applicable research scenarios clarified. Finally, an ISC safety protection framework covering the entire chain of “detection-diagnosis-early warning-mitigation-optimization design” is established. This review contributes to a deeper understanding of ISC-induced failure mechanisms, enhances early identification and monitoring capabilities, guides the development of replication methodologies, and provides technical and methodological support for reproducing defects and traces in safety accident investigations of LIBs.