Smart phase change composite for passive thermal management

A thermal management apparatus, comprising:

• a support structure disposed between two surfaces, the support structure having a lattice or honeycomb array of a plurality of cavities or cells each extending between a first side of the support structure and a second side of the support structure, wherein the first side of the support structure is disposed against a first of the two surfaces, and the second side of the support structure is disposed against a second of the two surfaces;
• a preformed thermally responsive phase change composite disposed in each of the plurality of cavities or cells, wherein the phase change composite in each of the plurality of cavities or cells is in contact with the second of the two surfaces and is offset from and not in contact with the first side of the support structure and the first of the two surface, the entire phase change composite expands upon heating to contact the first of the two surfaces and connect the two surfaces for increasing a thermal conductance between the two surfaces, the phase change composite shrinks upon subsequent cooling to reform the offset, the phase change composite is thermally insulating when not in an expanded state, and the phase change composite is formed of a phase change material intermixed and secured within a graphite block matrix material.