A battery system may include multiple battery cells grouped into modules. Each battery module may have a diffuser plate to direct the hot gases and molten material that are ejected during cell failure. The gas and material may be directed away from the nearest neighboring cells in the event of a single cell thermal runaway. Residual thermal energy is wicked away, absorbed or contained to keep heat away from the neighboring cells. These and other features may manage the blast energy and residual thermal energy of a single cell failure event. This may prevent a cascading failure of the larger battery system, thereby mitigating the risk of injury to personnel and property.