A thermal barrier for use in a power module assembly having at least one battery cell and corresponding method of forming. The thermal barrier includes at least one compressible member having one or more pockets. A first layer and a second layer are positioned adjacent to the compressive member at a first side and a second side, respectively. The thermal barrier includes one or more phase change materials configured to be deposited into the pockets. The phase change materials are configured to undergo an endothermic phase change reaction when a temperature is at or above an activation temperature. The first layer and the second layer may be configured to at least partially reflect radiant heat. In one example, the phase change materials include a bicarbonate salt.