A battery module includes a battery module housing, a heat exchanger including a plurality of fins disposed in the housing, a first lithium ion battery cell and a second lithium ion battery cell disposed within the battery module housing. The first lithium ion battery cell and the second lithium ion battery cell are separated by a fin of the plurality of fins. The module includes a temperature sensing component coupled to the fin separating the first and second battery cells. Filler material is disposed within the housing and between the battery cells and the fins to mechanically restrain the battery cells within the battery module housing. The filler materials conduct thermal energy between the battery cells and the fin. The filler material covers a free end of the fin and the temperature sensing component. The temperature sensing component is coupled to a conductor extending out of the filler material.