Multi-Physics Modeling of Thermal Runaway Propagation in a Li-Ion Battery Module

Thermal runaway failure of a li-ion battery can be induced for unavoidable reasons, e.g. external heat exposure or mechanical impact. After the initial single cell failure, propagation of such a failure within a battery module or pack shall be prevented to lessening the severity of its consequences.  To implement appropriate level of safety and obtain sufficient resistance to thermal runaway cascade, understanding the propagation mechanisms within cells configured electrically in series/parallel is crucial.

For complexity of the propagation phenomena, numerical modeling becomes an effective approach to capture cell and module instant response, identify propagation scenarios, and separate the impact of design factors. A 3-D electrochemical-electrical-thermal model has been developed utilizing NREL’s Multi-Scale Multi-Dimensional (MSMD) modeling approach. This CAE tool integrates electrochemical-thermal performance model, abuse reaction kinetics model of cell components, and electrical-thermal network models at module level.  It is designed to be used for addressing the influence of cell or module design factors and evaluating functionality of safety devices on preventing thermal runaway propagation.  This model is capable of capturing cell and module response to thermal, mechanical and electrical abuse, e.g. instant electric potential field after nail penetration shown in figure 1 (Figure 1 : Instant eletric potential field after a nail penetration test).

This paper presents our progress on identifying the characterization of thermal runaway propagation in a li-ion battery module. Modeling studies of design factors are carried out to provide design suggestion of improving module resistances to failure propagation. At module level, responses of battery modules with varied electrical configurations are predicted. At cell level, parametric and case studies are carried out to investigate and isolate the impact of other design factors, including cell capacity, chemistry, and type of assembly.