A module for a battery includes an enclosure, cells arranged within the enclosure, a space formed between the first main face of a cell and the second main face of an adjacent cell, the fluid occupying the space or spaces so as to cool the first main faces and/or the second main faces. The module includes flexible walls each extending facing and in contact with the first main face or the second main face of a cell and the flow rate of the fluid being controlled so as to make it possible to vary a pressure of the fluid applied to the flexible walls.