EP-4348756-B1 - SMART PHASE CHANGE COMPOSITE FOR PASSIVE THERMAL MANAGEMENT

Inventors

• AL-HALLAJ, SAID
• STOYANOV, STOYAN
• WANG, Hexu
• PLUNKETT, Samuel, T.
• MOREHOUSE, SCOTT
• PREZAS, PANOS

Dates

Publication Date

20260506

Application Date

20220524

Claims (17)

1. A thermal management apparatus (20, 120), comprising a thermally responsive material disposed between two surfaces, wherein the thermally responsive material changes upon heating, to increase a thermal conductance between the two surfaces, wherein the thermally responsive material comprises a phase change composite (30) disposed between the two surfaces, characterized in that the thermally responsive material is offset from one of the surfaces and expands upon heating to connect the two surfaces.
2. The apparatus of Claim 1, wherein an other of the surfaces is disposed adjacent to a heat source.
3. The apparatus of any one of Claims 1 or 2, wherein the phase change composite (30) comprises a phase change material selected from a paraffin wax, a hydrated salt, and combinations thereof.
4. The apparatus of any one of Claims 1 to 3, wherein the phase change composite (30) comprises a matrix material including graphite.
5. The apparatus of any one of Claims 1 to 4, further comprising a support structure (22) including a plurality of cavities or cells, each enclosing an amount of the thermally responsive material, the cavities or cells preferably including a cross-sectional shape selected from a circle, a square, a triangle, a hexagon, and combinations thereof.
6. The apparatus of any one of Claims 1 to 5, wherein the thermally responsive material changes from thermally insulating to thermally conductive upon the heating.
7. The apparatus of any one of Claims 1 to 6, wherein each of the two surface comprises a thermally conductive plate (40, 42).
8. The apparatus of any one of Claims 1 to 7, wherein the thermally responsive material is embodied as a film, a plate, a block, or an array of individual material components between the two surfaces.
9. The apparatus of any one of Claims 1 to 9, further comprising: a support structure (22) including a plurality of cavities or cells, each of the cavities or cells extending from a first end (26) to a second end (28); and a phase change composite (30) disposed in each of the plurality of cavities or cells, wherein the phase change composite (30) is offset by a predetermined distance (25) from the second end (28), and the phase change composite (30) is configured to expand toward the second end (28) upon a sufficient heat at the first end (26).
10. The apparatus of Claim 9, further comprising a thermally conductive surface over the second end (28).
11. The apparatus of Claim 9 or 10, wherein the first end (26) is disposed toward and/or against a heat source, and the second end (28) is disposed toward a cooling plate or channel.
12. The apparatus of any one of Claims 9 to 11, wherein the support structure (22) comprises a lattice or honeycomb of the plurality of open passages.
13. The apparatus of any one of the preceding claims, comprising: a support structure (22) including a lattice or honeycomb of a plurality of cavities or cells, the support structure (22) having a first side configured to be disposed toward or against a heat source, and a second side opposite the first side, and each of the cavities or cells extending from a first open end (26) on the first side of the support structure (22) to a second open end (28) on the second side of the support structure (22); and a phase change composite (30) disposed in each of the plurality of cavities or cells (52); and a conductive surface over the second open end (28) of the each of the cavities or cells, wherein the phase change composite (30) in the each of the plurality of cavities or cells is offset by a predetermined distance (25) from the conductive surface, and the phase change composite (30) is configured to expand toward the conductive surface upon a sufficient heat at the first side of the support structure.
14. The apparatus of Claim 13, wherein the heat source is a battery pack (50) of a plurality of electrochemical cells (52).
15. The apparatus of Claim 13 or 14, further comprising a second conductive surface over the first open end (26) of the each of the cavities or cells.
16. The apparatus of Claim 15, wherein the conductive surface is or is adjacent a housing wall for the heat source or a cooling channel.
17. A method of making a thermal management apparatus (20, 120) of any of the preceding claims, the method comprising forming a phase change composite (30) comprising a thermally responsive material and inserting the phase change composite (30) between two surfaces into a cell or cavity of a support structure (22), wherein the thermally responsive material changes upon heating to increase a thermal conductance between the two surfaces, characterized in that the composite is offset from at least one surface of the cell or cavity and expands upon heating to connect the two surfaces.

Description

FIELD OF THE INVENTION This invention relates generally to removing operational heat from electronic devices or battery packs and, more particularly, to phase change composite structures for temperature regulation in such devices or battery packs, and methods of manufacturing and use of said phase change composite structures, such as for removing excess heat generation. BACKGROUND OF THE INVENTION Temperature regulation is important for battery packs and other heat generating devices, such as electronic devices or motors. Uses of phase change materials, such as wax, are known to store and release heat. The phase change materials are known to be supported by matrix materials, such as an encapsulated wax or salt hydrate material in a graphite matrix. There is a continuing need for improved battery systems, and improved temperature regulation materials. WO 2020/1979282 discloses a thermal management apparatus with a phase change composite disposed between two surfaces according to the preamble of claim 1. SUMMARY OF THE INVENTION A general object of the invention is to improve removal of operational heat from a heat source, such as a battery pack or electronic device. The present invention includes or provides a passive thermal management apparatus, such as is usable with any heat source, for example, a battery pack, an electronic device (e.g., computer), an electric motor, etc. The passive thermal management system of embodiments of this invention acts as a thermal switch for activating increased heat transfer from the heat source to a conductive element. The passive thermal management system includes a thermally responsive material that expands upon absorbing thermal energy from the heat source, until it contacts a further thermal conductor to amplify energy thermal transfer away from the heat source. In other embodiments of this invention, the thermally responsive material is additionally electrically conductive, to further result in an electrical connection upon expansion to a secondary element/surface. The thermal management apparatus of embodiments of this invention can be considered a "smart" thermal switch for "passive" thermal management. The thermal switch is "smart" in that it can be designed to activate upon reaching a defined heat level within the adjacent heat source. The provided thermal management is "passive" in that there is no required active cooling such as using air or liquid to move the heat, nor active management by a sensor, processor, etc. The general object of the invention can be attained, at least in part, through a thermal management apparatus including a thermally responsive material disposed between two surfaces. The thermally responsive material changes upon heating, to increase a thermal conductance between the two surfaces, which are desirably thermally conductive plates or walls of other components of the heat source assembly. The thermally responsive material can be embodied as a film, a plate, a block, or an array of individual material components between the two surfaces. The thermally responsive material preferably changes from thermally insulating to thermally conductive upon the heating. In embodiments of this invention, the thermally responsive material is offset from a first of the surfaces and expands upon heating to connect the two surfaces. The thermally responsive material is preferably in contact with the second surface, which is the surface disposed toward or adjacent the heat source. In embodiments of this invention, the thermally responsive material includes a phase change material disposed between the two surfaces. The phase change material can be contained in a composite matrix material (e.g., graphite), and can be any suitable material, such as a paraffin wax, a hydrated salt, and combinations thereof. Embodiments of this invention include a support structure to contain and secure the thermally responsive material, as well as direct the expansion direction. The support structure desirably includes a plurality of cavities or cells, each enclosing an amount of the thermally responsive material. The cavities or cells preferably have a cross-sectional shape selected from a circle, a square, a triangle, a hexagon, and combinations thereof. The invention further includes a thermal management apparatus including a support structure with a plurality of cavities or cells, each of the cavities or cells extending from a first end to a second end. A phase change composite, such as described above, disposed in each of the plurality of cavities or cells, preferably in a lattice or honeycomb array, wherein the phase change composite is offset by a predetermined distance from the second end, and the phase change composite is configured to expand toward the second end upon a sufficient heat at the first end. A thermally conductive surface is desirably over the second end. In embodiments of this invention, the first end is disposed toward and/or against a heat source, and th