A battery system having a thermally conductive base member, a thermal interface member, and a battery module is provided. The thermal interface member is disposed on the thermally conductive base member and has first and second arcuate-shaped surfaces and a first groove. The battery module has a first pouch-type battery cell with a first outer housing having a first end portion with a first extension portion and first and second arcuate-shaped end surfaces. The first pouch-type battery cell is disposed directly on the thermal interface member such that the first extension portion is disposed in the first groove of the thermal interface member, and the first and second arcuate-shaped end surfaces are disposed directly on and against the first and second arcuate-shaped surfaces, respectively, of the thermal interface member.