In a battery pack having multiple battery cells distributed, for example, between multiple interconnected battery modules, a run-time cooling system is provided to cool (and/or heat) the battery cells during routine charging and discharging of the cells (e.g., powering a load such as a motor within an electric or hybrid-electric vehicle), and an emergency cooling system to cool the battery cells in response to a signal indicating detection of one or more conditions indicating possible thermal runaway within the battery cells or battery modules. The run-time cooling system, which may include a fan, HVAC unit or other fluid pumping device, induces continuous coolant flow within the battery pack (e.g., flow of air or other gaseous or liquid coolant). The emergency cooling system, by contrast, includes a mechanical interface or is otherwise adapted to receive a receptacle containing pressurized coolant or other flash-cooling device.