The Safe Operating Area (SOA) of lithium-ion (Li-ion) batteries defines the permissible range of operational conditions (e.g., temperature, voltage) within which a battery can operate safely and reliably, avoiding damage, performance degradation, or critical hazards such as thermal runaway. Although the SOA concept plays a central role in battery safety and performance optimization, its continuous evolution has led to varied, inconsistent, and fragmented definitions and approaches throughout the scholarly literature. This lack of a unified perspective hinders both practical implementation and the development of a coherent conceptual understanding.
This work addresses this issue by establishing a systematic and cohesive framework for the SOA. First, the diverse viewpoints presented in the literature are analyzed and structured, and related topics from adjacent fields are integrated to form a clearer conceptual basis. The strengths and limitations of existing approaches are then critically evaluated to identify how well they capture the complexity of the SOA concept. Based on this comparative assessment, a comprehensive perspective for conceptualizing the SOA is derived. Building on these insights, the key building blocks of the SOA are systematically defined and integrated into a unified framework. Using this framework, an SOA design is developed and discussed to illustrate how the proposed structure can support consistent development and practical application of Safe Operating Areas for lithium-ion batteries.