Safety analysis of thermal runaway in LTO battery cells under operational fault conditions in railway vehicles

Lithium-titanate oxide (LTO) batteries are widely adopted in transportation owing to their high safety, long lifespan, and excellent high C-rate capability. However, studies investigating the thermal runaway behavior of LTO cells under railway operating conditions are limited. In particular, the influence of fault scenarios and environmental factors on battery safety and passenger evacuation time warrants further investigation. To address this, a multi-scale multi-domain (MSMD) model was developed, incorporating a 2RC equivalent circuit model (ECM) for electrochemical behavior and a four-equation model for thermal runaway reactions. Simulations were performed using railway driving profiles under ambient temperatures of - 10, 25, and 40 °C, and heat transfer coefficients (HTC) of 10, 30, and 50 W/m²K. A thermal runaway safety index (STR) was introduced to quantitatively assess battery safety across varying fault and environmental conditions. The results indicated that high ambient temperatures and low cooling efficiency significantly elevate the risk and severity of thermal runaway. Notably, scenarios with a 10 W/m²K HTC and a 5 mΩ external short circuit yielded the lowest STR, indicating a critical safety risk. These findings provide valuable insights for designing safer battery systems and ensuring sufficient evacuation time in railway vehicles equipped with LTO batteries.