FLEXIBLE COMPOSITES CONTAINING GRAPHITE AND FILLERS
Resin-free, flexible composites of graphite leaf, containing fillers other than natural graphite, which has higher thermal conductivity than conventional 100% natural graphite based graphite sheet/foil/paper, and methods of preparing such flexible composites. In a second embodiment, there is a thermal management system comprising at least one flexible composite as set forth just above, wherein a graphite surface of a flexible composite is in thermal contact with a heat source of a heat generating device.
1 . Resin free flexible composites of graphite leaf, containing fillers selected from the group consisting of:
i. fibers,
ii. powders, and,
iii. flake.
2 . The flexible composite as claimed in claim 37 wherein said non-natural graphite filler content is from 0.1 weight % to 80 weight % based on the total weight of said graphite leaf and non-natural, graphite filler.
3 . The flexible composite as claimed in claim 37 wherein said non-natural, graphite filler content is from 0.5 weight to 60 weight % based on the total weight of said graphite leaf and non-natural, graphite filler.
4 . The flexible composite as claimed in claim 37 wherein said non-natural, graphite filler content is from 1 weight % to 40 weight % based on the total weight of said graphite leaf and non-natural, graphite filler.
5 . The flexible composite as claimed in claim 37 wherein said non-natural, graphite filler content is from 2 weight % to 30 weight % based on the total weight of said graphite leaf and non-natural, graphite filler.
6 . A flexible composite as claimed in claim 1 comprising natural graphite and filler materials which have an in-plane thermal conductivity higher than 400 W/mK and a thickness thinner than 100 um.
7 . The flexible composite as claimed in claim 1 wherein said graphite and said fillers are heterogeneous across the width of said composite.
8 . The flexible composite as claimed in claim 37 wherein said flexible composite is compressed.
9 . The flexible composite as claimed in claim 37 wherein said composite has various shapes.
10 . The flexible composite as claimed in claim 37 comprising natural graphite and non-natural, graphite filler materials which have in-plane thermal conductivity higher than 400 W/mK.
11 . The flexible composite as claimed in claim 10 with a thickness ranging from 5 um to 1000 um.
12 . The flexible composite as claimed in claim 10 with a thickness ranging from 10 um to 800 um.
13 . The flexible composite as claimed in claim 10 with a thickness ranging from 15 um to 600 um.
14 . The flexible composite as claimed in claim 10 with a thickness ranging from 20 um to 400 um.
15 . The flexible composite as claimed in claim 10 with a thickness ranging from 25 um to 300 um.
16 . A thermal management system as claimed in claim 15 designed for portable electronics devices.
17 . The flexible composite as claimed in claim 37 wherein there is a first side and a second side and said first side of said composite has more graphite and said second side has more non-natural, graphite filler than said first side.
18 . The flexible composite as claimed in claim 37 wherein there is a first side and a second side, said graphite is predominantly on said first, side of said leaf, and said non-natural, graphite filler material is predominantly on said second side and said graphite and said non-natural, graphite filler are interpenetrating.
19 . The flexible composite as claimed in claim 37 wherein said composite consists of a graphite rich layer in a first composition with more than 80% of graphite in said first composition and a non-natural, graphite filler rich layer in a second composition with more than of non-natural graphite filler material in said second composition.
20 . The flexible composite as claimed in claim 37 wherein said composite consists of a layer in which the ratio of graphite and non-natural, graphite filler material changes throughout the thickness direction.
21 . The flexible composite as claimed in claim 37 wherein the thermal conductivity in the through-plane direction is higher than the thermal conductivity in the through-plane direction of a 100% graphite composite.
22 . A thermal management system comprising a flexible composite of claim 37 , wherein a graphite surface of said flexible composite is in thermal contact with a heat source from a heat generating device.
23 . The thermal management system as claimed in claim 22 in a portable electronic device.
24 . The thermal management system as claimed in claim 22 in an LED device.
25 . The thermal management system as claimed in claim 22 in an industrial device.
26 . The thermal management system as claimed in claim 22 in a medical device.
27 . The thermal management system as claimed in claim 22 in a military device.
28 . The thermal management system as claimed in claim 22 in a device for aerospace vehicles.
29 . The thermal management system as claimed in claim 22 in a device for automotive vehicles.
30 . The thermal management system as claimed in claim 22 in a device for train systems.
31 . The flexible composite as claimed in claim 37 comprising two natural graphite layers and non-natural, graphite filler materials, each having surfaces, wherein said non-natural, graphite filler surfaces are in thermal contact with two independent thermal sources.
32 . The thermal management system as claimed in claim 22 comprising said flexible composite wherein said two graphite surfaces are in thermal contact with two thermal sources.
33 . The thermal management system as claimed in claim 32 wherein said thermal sources are batteries.
34 . A method of forming a flexible composite as claimed in claim 37 wherein said flexible composite is formed by compressing graphite and at least one non-natural, graphite filler material together.
35 . The flexible composite as claimed in claim 37 wherein said graphite is exfoliated.
36 . A method of forming a flexible composite as claimed in claim 37 wherein said graphite and said non-natural fillers are deposited from a slurry and then compressed.
37 . A method of forming a flexible composite as claimed in claim 36 wherein said slurry is partially segregated to form a heterogeneous composite.
38 . A resin-free flexible composite of graphite leaf containing non-natural, graphite fillers, said non-natural, graphite fillers being selected from the group consisting essentially of: fibers, fibrils, powders, particles, and, flakes, said flexible composite having a predetermined width, wherein said graphite and said non-natural, graphite fillers are heterogeneous across said width of said composite.
39 . A thermal management system comprising a flexible composite of claim 37 , wherein there are two graphite surfaces and said two graphite surfaces are in thermal contact with two thermal sources.