Traction battery pack thermal management system and method

A thermal management system for a traction battery pack, comprising:

• at least one cell stack having a plurality of battery cells;
• a thermal exchange device adjacent the at least one cell stack, the thermal exchange device including a first plate and a second plate, the first plate and the second plate spaced from each other to provide at least one coolant passageway that communicates a coolant, the first plate having a first side that faces the at least one cell stack and the second plate having a second side opposite the first side;
• and
• a plurality of thermal breaks in the thermal exchange device, the plurality of thermal breaks configured to inhibit thermal energy transfer from a first area of the thermal exchange device to a different, second area of the thermal exchange device, the plurality of thermal breaks provided at least in part by blind-hole apertures in the first plate, the blind-hole apertures opening to the first side and not extending through the second plate.