Abstract: An apparatus for transferring thermal energy to or from a battery cell is disclosed, which includes a thermally conductive plate enclosing a conduit in communication with an inlet for receiving a heat transfer fluid stream and being configured to cause the fluid to flow through the plate to an outlet. The plate has a surface for receiving thermal energy generated by operation of the battery cell and is operable to couple thermal energy to the fluid. In one aspect the plate includes first and second opposing walls and the conduit includes a first conduit portion formed in the first wall and a second corresponding conduit portion formed in the second wall defining the conduit. In another aspect the conduit includes an aperture in a central wall and first and second cover walls on either side of the central wall. The cover walls enclose aperture and provide a seal.