A battery system, comprising: a thermally conductive base member; a thermal interface member disposed on a surface of the thermally conductive base member, the thermal interface member having first and second arcuate-shaped surfaces (70, 72) and a first groove, the first groove being disposed between the first and second arcuate-shaped surfaces (70, 72) and extending into the thermal interface member; a battery module having a first pouch-type battery cell, the first pouch-type battery cell having a first outer housing with a first end portion and a second end portion, the first end portion of the first outer housing having a first extension portion and first and second arcuate-shaped end surfaces (470, 472), the first extension portion of the first outer housing having a first end and a second end, the first arcuate-shaped end surface of the first outer housing extending from the first end of the first extension portion of the first outer housing, the second arcuate-shaped end surface of the first outer housing extending from the first end of the first extension portion of the first outer housing and away from the first arcuate-shaped end surface of the first outer housing; and the first pouch-type battery cell being disposed directly on the thermal interface member such that the first extension portion of the first pouch-type battery cell is disposed in the first groove of the thermal interface member, and the first extension portion of the first outer housing directly contacts the thermal interface member, and the first and second arcuate-shaped end surfaces (470, 472) of the first pouch-type battery cell are disposed directly on and against the first and second arcuate-shaped surfaces (70, 72), respectively, of the thermal interface member. a thermally conductive base member; a thermal interface member disposed on a surface of the thermally conductive base member, the thermal interface member having first and second arcuate-shaped surfaces (70, 72) and a first groove, the first groove being disposed between the first and second arcuate-shaped surfaces (70, 72) and extending into the thermal interface member; a battery module having a first pouch-type battery cell, the first pouch-type battery cell having a first outer housing with a first end portion and a second end portion, the first end portion of the first outer housing having a first extension portion and first and second arcuate-shaped end surfaces (470, 472), the first extension portion of the first outer housing having a first end and a second end, the first arcuate-shaped end surface of the first outer housing extending from the first end of the first extension portion of the first outer housing, the second arcuate-shaped end surface of the first outer housing extending from the first end of the first extension portion of the first outer housing and away from the first arcuate-shaped end surface of the first outer housing; and the first pouch-type battery cell being disposed directly on the thermal interface member such that the first extension portion of the first pouch-type battery cell is disposed in the first groove of the thermal interface member, and the first extension portion of the first outer housing directly contacts the thermal interface member, and the first and second arcuate-shaped end surfaces (470, 472) of the first pouch-type battery cell are disposed directly on and against the first and second arcuate-shaped surfaces (70, 72), respectively, of the thermal interface member.