Provided are cooling subsystems for energy-storage systems comprising: a coolant section having a coolant circulated therein; a non-coolant section having a fluid other than the coolant disposed therein; a plurality of battery cells having a coated portion and a non-coated portion, the coated portion being disposed in the coolant section, and the non-coated portion being disposed in the non-coolant section. Some embodiments may also comprise a retainer disposed between the coolant section and the non-coolant section, the retainer holding the plurality of battery cells, the retainer forming a seal around the plurality of battery cells, the seal preventing the flow of coolant from the coolant section to the non-coolant section.