Numerical study on thermal runaway of LTO lithium-ion battery cells with different design and operating conditions

Abstract

Lithium-ion batteries are widely used in various industries, particularly in the transportation sectors, owing to their high-power capacity. Despite these advantages, ensuring their safety remains a serious challenge, as thermal runaway and subsequent thermal propagation events pose substantial risks. Various studies have been conducted on the thermal runaway of battery cells. However, research on battery shape and operating conditions is lacking. In this study, the effects of battery shape and operating conditions on the thermal runaway of lithium titanate oxide battery cells are numerically investigated. An equivalent circuit model and NREL’s four-equation model are employed for the electrochemical reactions and thermal runaway. Prismatic cells demonstrated better heat dissipation compared to cylindrical cells, resulting in a delayed onset of thermal runaway but with a higher thermal runaway temperature. Under non-operating conditions, the thermal runaway occurred 40 s later in prismatic cells, with an 83.5 K higher maximum temperature. Conversely, cylindrical cells experienced faster heat accumulation in the core, leading to an earlier onset of thermal runaway by 295 s compared to prismatic cells under operating conditions. Under operating conditions, the onset of thermal runaway was significantly accelerated. Cylindrical cells reached the thermal runaway temperature at 165 s, which is 345 s earlier than under non-operating conditions, with a peak temperature rate of 33.9 K s⁻¹, up from 17.5 K s⁻¹. Similarly, prismatic cells reached a peak temperature rate of 33 K s⁻¹ compared to 18.1 K s⁻¹ under non-operating conditions. These findings underscore the critical role of battery shape and operating conditions in determining the thermal runaway characteristics.