Abstract: Traction battery pack designs for use in electrified vehicles may include a thermal barrier system adapted for mitigating thermal propagation inside of the traction battery pack during battery thermal events. The thermal barrier system may include features such as a bifurcation structure and/or a canopy structure. The bifurcation structure is adapted for substantially isolating a first portion of an enclosure interior where a first battery internal component (e.g., a first battery array) resides from a second portion of the enclosure interior where a second battery internal component (e.g., a second battery array) resides, and the canopy structure is adapted for protecting a bus bar assembly of the traction battery pack.