Battery pack assembly having thermal transfer sheets and heat sink
A battery pack thermal management assembly draws heat from prismatic batteries having opposed major surfaces and arranged in a stacked configuration inside a housing. The thermal management assembly includes a plurality of thermal transfer sheets made from sheets of a compressed mass of exfoliated graphite particles. Each thermal transfer sheet is positioned to contact the major surface of at least one of the prismatic batteries. A cover plate has a top face and a bottom face and includes a plurality of apertures through which the plurality of thermal transfer sheets extend. The apertures include at least one curved sidewall and the thermal transfer sheets are bent over the curved sidewall. At least a portion of each of the thermal transfer sheets is secured between a heat sink and the top face.
1. A battery pack thermal management assembly for drawing heat from a plurality of generally rectangular prismatic batteries having opposed major surfaces and arranged in a stacked configuration inside a housing, the battery pack thermal management assembly comprising;
a plurality of thermal transfer sheets made from sheets of a compressed mass of exfoliated graphite particles, each said thermal transfer sheet being positioned to contact the major surface of at least one of the prismatic batteries;
a cover plate having a to face and a bottom face and including a plurality of apertures through which the plurality of thermal transfer sheets extend, said apertures including at least one curved sidewall, said thermal transfer sheets being bent over said curved sidewall; and
a heat sink positioned on top of said cover plate, at least a portion of each of said thermal transfer sheets being secured between said heat sink and said top face.
2. The battery pack thermal management assembly of claim 1 wherein said thermal transfer sheets extend into said apertures substantially perpendicular from said bottom face and substantially parallel to said top face.
3. The battery pack thermal management assembly of claim 1 wherein said curved sidewall includes a radius between about 1 mm and about 10 mm.
4. The battery pack thermal management assembly of claim 1 wherein said curved sidewall includes a radius of between about 2 mm and about 5 mm.
5. The battery pack thermal management assembly of claim 1 wherein said sheet of a compressed mass of exfoliated graphite panicles includes an in-plane thermal conductivity of at least about 250 W/mK.
6. The battery pack thermal management assembly of claim 1 wherein said sheet of a compressed mass of exfoliated graphite particles includes an in-plane thermal conductivity of at least about 400 W/mK.
7. The battery pack thermal management assembly of claim 1 wherein one of said plurality of thermal transfer sheets is positioned between each pair of adjacent prismatic batteries in the stack.
8. The battery pack thermal management assembly of claim 1 wherein said heat sink is made of a thermally conductive metal and includes fins.
9. The battery pack thermal management assembly of claim 1 wherein said heat sink comprises a manifold through which a thermal transfer medium flows.
10. The battery pack thermal management assembly of claim 1 wherein said thermal transfer sheets comprise a minimum bend radius achievable without cracking said thermal transfer sheets, wherein the radius of said curved sidewall is greater than the minimum bend radius to prevent cracking of said thermal transfer sheet.
11. The battery pack thermal management assembly of claim 1 wherein each said apertures is sized and positioned to receive therethrough more than one of said plurality of thermal transfer sheets.
12. The battery pack thermal management assembly of claim 1 wherein said thermal transfer sheets are in contact with said curved sidewall.
13. The battery pack thermal management assembly of claim 1 wherein said thermal transfer sheets further comprise an adhesive coating contacting said curved surface and said top face.
14. The battery pack thermal management assembly of claim 1 wherein said thermal transfer sheets comprise composite materials.
15. The battery pack thermal management assembly of claim 14 wherein said thermal transfer sheets each comprise pairs of graphite sheets having a phase change material disposed therebetween.
16. The battery pack thermal management assembly of claim 15 wherein said phase change material is free flowing and contained by said graphite sheets.
17. The battery pack thermal management assembly of claim 15 wherein said thermal transfer sheets each comprise pairs of graphite sheets having a carrying matrix positioned therebetween, said carrying matrix comprising a compressed expanded graphite mat or a carbon foam, and wherein a phase change material is adsorbed into the carrying matrix.
18. The battery pack thermal management assembly of claim 14 wherein the composite material comprises a single graphite sheet layer secured to a single carrying matrix layer having a phase change material absorbed therein.
19. The battery pack thermal management assembly of claim 1 wherein said thermal transfer sheets have two major surfaces and further comprising an electrically insulating film on one or both major surfaces.