A battery cell assembly having a cooling fin with a tube and a flexible thermally conductive sheet disposed on the tube is provided. The tube has first, second, and third tube portions. The sheet has first, second, and third sheet portions. The first and second sheet portions are disposed on at least the first and second tube portions, respectively, and the third sheet portion extends between the first and second tube portions. The assembly further includes a first clamping member clamping the first sheet portion to the first tube portion, and a second clamping member clamping the second sheet portion to the second tube portion. The assembly further includes a battery cell disposed against the third sheet portion.