Quantitative Assessment of State of Safety of Lithium-ion Batteries

The increasing adoption of lithium-ion batteries (LIBs) in applications such as electric vehicles (EVs) and aerospace systems necessitates higher energy and power densities. However, this also raises significant safety concerns due to risks of catastrophic events such as thermal runaway, explosions, and fires. Current battery safety assessments are largely qualitative and lack a standardized numerical metric for real-time risk evaluation. This paper strives to improve the concept of state of safety (SOS), a quantitative function that defines battery safety as decreasing with increasing levels of abuse. The SOS function integrates key abuse parameters, including voltage, current, temperature, and mechanical deformation, to provide continuous safety assessments. A sensitivity-based approach is introduced to quantify the relative impact of different abuse conditions, enabling predictive risk evaluation. Furthermore, various degradation modes are analyzed to facilitate proactive maintenance strategies. By offering a structured, real-time safety monitoring methodology, SOS enhances hazard prevention in high-risk applications, improving battery reliability and safety.