Abstract: A thermal management apparatus and method of use, such as in a battery pack or electronic device. A thermally responsive material is disposed between two surfaces, wherein the thermally responsive material changes upon heating, to increase a thermal conductance between the two surfaces. The thermally responsive material is offset from one of the surfaces and expands upon heating to connect the two surfaces. The thermally responsive material is a phase change composite including a phase change material selected from a paraffin wax, a hydrated salt, and combinations thereof.

Abstract: A method for making a phase change composite (PCC) for a battery pack of a plurality of electrochemical cells. The method includes impregnating a matrix material with a phase change material, and fragmenting the matrix material before or after the impregnating. The fragmented and impregnated matrix material are shaped into a composite such as by extraction, pressing, or other molding technique. Additional PCC shapes are provided by this invention, such as individual spacers for placement between individual battery cells, or rows of cells.