CN115441098B - Graphite heat conduction assembly and preparation method thereof - Google Patents

Graphite heat conduction assembly and preparation method thereof Download PDF

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Publication number
CN115441098B
CN115441098B CN202211235781.3A CN202211235781A CN115441098B CN 115441098 B CN115441098 B CN 115441098B CN 202211235781 A CN202211235781 A CN 202211235781A CN 115441098 B CN115441098 B CN 115441098B
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heat conduction
graphite
foam
layer
buffer layer
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CN115441098A (en
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郑志成
朱全红
周招团
黄治豪
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Dongguan Hongyi Thermal Conductmty Material Co ltd
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Dongguan Hongyi Thermal Conductmty Material Co ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/65—Means for temperature control structurally associated with the cells
    • H01M10/653—Means for temperature control structurally associated with the cells characterised by electrically insulating or thermally conductive materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form
    • B32B3/26—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer
    • B32B3/266—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer characterised by an apertured layer, the apertures going through the whole thickness of the layer, e.g. expanded metal, perforated layer, slit layer regular cells B32B3/12
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
    • B32B5/18—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by features of a layer of foamed material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B9/00—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00
    • B32B9/005—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00 comprising one layer of ceramic material, e.g. porcelain, ceramic tile
    • B32B9/007—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00 comprising one layer of ceramic material, e.g. porcelain, ceramic tile comprising carbon, e.g. graphite, composite carbon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B9/00—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00
    • B32B9/04—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00 comprising such particular substance as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B9/00—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00
    • B32B9/04—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00 comprising such particular substance as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B9/046—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00 comprising such particular substance as the main or only constituent of a layer, which is next to another layer of the same or of a different material of foam
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/61—Types of temperature control
    • H01M10/613—Cooling or keeping cold
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/62—Heating or cooling; Temperature control specially adapted for specific applications
    • H01M10/625—Vehicles
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/65—Means for temperature control structurally associated with the cells
    • H01M10/655—Solid structures for heat exchange or heat conduction
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/65—Means for temperature control structurally associated with the cells
    • H01M10/659—Means for temperature control structurally associated with the cells by heat storage or buffering, e.g. heat capacity or liquid-solid phase changes or transition
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
    • H01M50/233—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders characterised by physical properties of casings or racks, e.g. dimensions
    • H01M50/242—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders characterised by physical properties of casings or racks, e.g. dimensions adapted for protecting batteries against vibrations, collision impact or swelling
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
    • H01M50/244—Secondary casings; Racks; Suspension devices; Carrying devices; Holders characterised by their mounting method
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
    • H01M50/249—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders specially adapted for aircraft or vehicles, e.g. cars or trains
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2266/00—Composition of foam
    • B32B2266/02—Organic
    • B32B2266/0214—Materials belonging to B32B27/00
    • B32B2266/0278—Polyurethane
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/30—Properties of the layers or laminate having particular thermal properties
    • B32B2307/302—Conductive
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B32B2307/56—Damping, energy absorption

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Ceramic Engineering (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Secondary Cells (AREA)
  • Laminated Bodies (AREA)

Abstract

The application relates to a graphite heat conduction assembly and a preparation method thereof, and relates to the field of heat conduction materials, wherein the graphite heat conduction assembly comprises two graphite heat conduction layers, a buffer layer is arranged between the two graphite heat conduction layers, a plurality of guide holes are formed in the buffer layer in a penetrating manner, the guide holes are communicated with the two graphene heat conduction layers, and heat conduction slurry is filled in the guide holes; the buffer layer is made of foam cotton and heat conducting filler filled in the pores inside the foam cotton. The application is prepared by compounding the graphite heat conduction layer and the foam cotton buffer layer, has good heat conduction performance, and can provide a certain buffer effect to protect the battery pack. The heat conduction paste is filled on the side of the through holes formed in the foam cotton to improve the unidirectional heat conduction performance of the heat conduction component.

Description

Graphite heat conduction assembly and preparation method thereof
Technical Field
The application relates to the field of heat conducting materials, in particular to a graphite heat conducting component and a preparation method thereof.
Background
With the rapid development of new energy automobiles, the requirements on the battery capacity and the safety performance of the automobiles are also higher and higher. The power battery pack is used as one of the most main power sources of the new energy automobile, various electrochemical changes and physical changes occur in the charge and discharge processes of the power battery, and a large amount of heat can be generated in the operation process of the battery, but the battery pack is not subjected to timely heat dissipation treatment, the service life of the battery can be greatly influenced by long-time heat accumulation, and meanwhile, the battery pack has a great safety problem.
The heat dissipation structure of the battery pack of the new energy automobile commonly used in the prior art comprises air-cooled heat dissipation, water-cooled heat dissipation and the like, a heat conduction layer is generally arranged between the heat dissipation device and the power battery pack, generated heat is quickly conducted to the heat dissipation device through the heat conduction layer, and the heat is quickly dissipated through the heat dissipation device. The Chinese patent application with publication number of CN113097604A discloses a special graphene heat dissipation assembly with low thermal resistance, high compressibility and buffer function for an electric automobile, wherein the graphene heat dissipation assembly comprises a top layer graphite sheet, a graphite sponge composite cylinder and a bottom layer graphite sheet which are sequentially connected from top to bottom; the graphite sponge composite cylinder comprises a modified cylinder sponge and a coated graphite sheet, and the coated graphite sheet is wound and wrapped on the surface of the modified cylinder sponge. The sponge microporous structure can absorb external impact force and protect a battery component of the electric automobile; meanwhile, the graphene filled in the micropores of the sponge can conduct heat energy. However, in the structure, larger pores exist between the graphite sheets and the middle graphite sponge composite cylinder structure, and larger air thermal resistance exists when the structure is used, so that the heat conduction process of the graphene heat dissipation assembly is greatly influenced, and the heat conduction performance is still to be improved.
Disclosure of Invention
Aiming at the related problems in the prior art, the application provides the graphite heat conduction component and the preparation method thereof, so that the graphite heat conduction component has a certain buffering effect and good heat conduction performance.
In a first aspect, the present application provides a graphite heat conduction assembly, which adopts the following technical scheme:
the graphite heat conduction assembly comprises two graphite heat conduction layers, a buffer layer is arranged between the two graphite heat conduction layers, a plurality of guide holes are formed in the buffer layer in a penetrating mode, the guide holes are communicated with the two graphite heat conduction layers, and heat conduction slurry is filled in the guide holes; the buffer layer comprises foam cotton and heat-conducting filler filled in pores inside the foam cotton.
Through adopting above-mentioned technical scheme, the graphite heat conduction layer that is located both sides is used for with heating element or radiating element contact laminating, can have good contact nature with heating element or between the heat conduction assembly, plays fine heat transfer effect. The middle buffer layer is made of foam, the foam has good compression elasticity, a good buffer effect can be achieved, the heat-conducting filler is filled in the pores inside the foam, the air thermal resistance inside the foam can be reduced, the heat-conducting filler has good heat conductivity, and the heat conductivity of the buffer layer can be effectively improved while the air thermal resistance of the foam is reduced. And the foam cotton is provided with a guide hole, the guide hole is filled with heat-conducting slurry, the heat-conducting slurry is used for communicating graphite heat-conducting layers on two sides, the heat-conducting slurry has good heat conduction effect, a further heat-conducting channel is provided for the buffer layer, and the heat-conducting performance is improved.
The graphite heat conduction component is prepared by compounding the graphite heat conduction layer and the foam cotton buffer layer, has good heat conduction performance, and can provide a certain buffer effect to protect the battery pack. The heat conduction paste is filled on the side of the through holes formed in the foam cotton to improve the unidirectional heat conduction performance of the heat conduction component.
Optionally, the buffer layer includes multilayer foam cotton and graphite flake that stacks gradually, heat conduction filler pack in foam cotton internal pore, the guiding hole runs through foam cotton and graphite flake.
By adopting the technical scheme, the buffer layer is prepared from the foam cotton and the graphite sheets which are stacked in sequence, and the foam cotton with thicker single layer is replaced by the foam cotton with thinner multiple layers, so that the porosity in the foam cotton can be effectively reduced and the air thermal resistance can be reduced on the premise that the compression rebound effect of the buffer layer is not affected when the total thickness of the buffer layer is the same; in addition, a layer of graphite sheets is overlapped between each layer of foam cotton, so that the buffer layer has better heat conduction performance. The buffer effect is that the compression rebound between the multi-layer foaming cotton is matched with each other, so that a better buffer effect can be provided. Through the cooperation of the graphite flake and the foam cotton that stacks gradually, also can promote the stiffness of buffer layer, reduce the deformation of buffer layer after long-time use. In still another aspect, the buffer layer is formed by sequentially overlapping the multi-layer foam cotton and the graphite sheets, so that the thickness of the single-layer foam cotton is reduced, the influence of heat conduction slurry in the guide hole on the elastic energy of the retraction of the buffer layer can be reduced, and the buffer performance of the graphite heat conduction assembly is improved.
Optionally, the thickness of the single-layer foam cotton is 2-5 mm, and the thickness of the graphite sheet is 1-3 mm.
Optionally, the thickness of the buffer layer is 15-30 mm, and the thickness of the graphite heat conduction layer is 2-5 mm.
Through adopting above-mentioned technical scheme, the adoption lower thickness of single-layer foaming cotton is favorable to the packing of heat conduction filler in the foaming cotton inside, makes it have certain supporting strength when not influencing its cushioning effect. When the thickness of the graphite sheet is too thin, the strength of the graphite sheet is low, and the graphite sheet is easy to break in the vibration or compression deformation process; and the thickness of the graphite flake can influence the overall thickness of the buffer layer when being too thick, and the total layer number of the foam cotton can be reduced when the requirement of the thickness of the buffer layer is higher, so that the compression rebound resilience performance and the buffer effect of the buffer layer are influenced. In the same way, the thickness of the buffer layer is limited to be in the range of 20-30 mm, and the graphite heat conduction assembly can maintain good structural stability while having good compression rebound buffer effect.
Optionally, the heat conductive filler is a liquid metal.
Further preferably, the liquid metal includes any one of gallium indium alloy, gallium tin alloy and gallium indium tin alloy.
Through adopting above-mentioned technical scheme, liquid metal is an alloy that has lower fusing point, and its temperature rises to certain extent can change into flowing state from the solid state, fills liquid metal into the inside hole of foaming cotton, and liquid metal can provide good heat conduction effect for foaming cotton. When the battery pack heats to a certain extent, the heated temperature of the buffer layer exceeds the melting point range of the liquid metal, the liquid metal in the pores inside the buffer layer is heated to be changed into a flowing state, so that the pores inside the foam can be further filled, and the heat conducting property of the buffer layer is improved.
Optionally, the foam cotton is any one of polyurethane foam cotton, polyethylene foam cotton, polyvinyl chloride foam cotton, silica gel foam cotton and polyimide foam cotton.
Further preferably, the porosity of the foam is 45 to 60%.
By adopting the technical scheme, the porosity of the foam cotton is limited to 45-60%, so that the foam cotton has a certain good rebound effect and simultaneously keeps good stiffness and mechanical support strength.
Optionally, the heat-conducting slurry comprises the following raw materials in percentage by weight: 25-40% of graphite powder, 50-70% of adhesive and 5-10% of dispersing agent.
Optionally, the adhesive is at least one of epoxy resin, polyurethane, acrylic resin and silicone rubber.
Optionally, the dispersing agent is any one of sodium dodecyl sulfate, sodium hydroxymethyl cellulose, sodium tripolyphosphate and sodium dodecyl benzene sulfonate.
By adopting the technical scheme, the graphite powder has good heat conduction performance, and the dispersing agent can improve the dispersion degree of the graphite powder in the adhesive, so that the graphite powder and the adhesive are uniformly dispersed. The binder is preferably a resin material with good heat conduction performance, and can play a good role in heat conduction after being filled into the guide holes as filling slurry by matching with graphite powder.
Optionally, the aperture of the guide hole is 2-6 mm; the center distance between adjacent guide holes is 10-20 mu m.
By adopting the technical scheme, the aperture of the guide hole and the distance between the adjacent guide holes can influence the heat conduction performance of the strength of the buffer layer, and too dense guide holes or too large apertures can cause too much filling of the heat conduction slurry to influence the compression rebound effect of the buffer layer; and when the guide holes are too sparse or the aperture is too small, the promotion degree of the heat conduction performance is effective, the heat conduction effect is poor, and the filling of the heat conduction filler is not facilitated due to the too small guide holes. In combination, the diameter and spacing of the pilot holes are limited to the above ranges, and may provide both good compression resilience and thermal conductivity.
Optionally, a sealing layer is further disposed on the side edge of the buffer layer parallel to the guiding hole.
Through adopting above-mentioned technical scheme, the foam has porous structure, and the heat conduction filler of filling wherein exists the risk of spilling from the side, seals the pore around through the banding layer, avoids heat conduction filler to drop from the buffer layer and influence the heat conductivility of product in the graphite heat conduction subassembly use.
In a second aspect, the application provides a preparation method of a graphite heat conduction assembly, which adopts the following technical scheme:
the preparation method of the graphite heat conduction component comprises the following steps:
s1, cutting foam cotton into specified thickness, and then forming guide holes in the heat-conducting foam cotton;
s2, spraying a layer of adhesive on the side edges of the foam cotton parallel to the axial direction of the guide hole, and forming an edge sealing layer after the adhesive is solidified; s3, uniformly filling the heat-conducting filler into the gaps inside the foam cotton, and then injecting the heat-conducting slurry into the guide holes;
and S4, pressing the graphite heat conducting sheets on two sides of the foam cotton before solidification of the heat conducting slurry, and adhering and fixing the graphite heat conducting sheets on the foam cotton after solidification of the heat conducting slurry to prepare the graphite heat conducting assembly.
Optionally, when the buffer layer includes a plurality of layers of graphite sheets and foam cotton stacked in sequence, step S3 includes: and uniformly filling the heat-conducting filler into the pores in the foam cotton, sequentially stacking the foam cotton and the graphite sheets which are the same in size and provided with the guide holes to a specified height, and injecting the heat-conducting filler into the guide holes after stacking.
Through adopting above-mentioned technical scheme, carry out the mutual bonding after multilayer graphite flake and foaming cotton are solidified through the heat conduction thick liquids in the guiding hole, at the in-process of filling heat conduction thick liquids, partial heat conduction thick liquids can spill over and fill to between each layer, play further bonding fixed effect.
In summary, the present application includes at least one of the following beneficial technical effects:
1. the graphite heat conduction component is prepared by compounding the graphite heat conduction layer and the foam cotton buffer layer, has good heat conduction performance, and can provide a certain buffer effect to protect the battery pack. The heat conduction paste is filled on the side of the through holes formed in the foam cotton to improve the unidirectional heat conduction performance of the heat conduction component.
2. Through the cooperation of the graphite flake and the foam cotton that stacks gradually, also can promote the stiffness of buffer layer, reduce the deformation of buffer layer after long-time use. In still another aspect, the buffer layer is formed by sequentially overlapping the multi-layer foam cotton and the graphite sheets, so that the thickness of the single-layer foam cotton is reduced, the influence of heat conduction slurry in the guide hole on the elastic energy of the retraction of the buffer layer can be reduced, and the buffer performance of the graphite heat conduction assembly is improved.
3. The heat conducting filler is preferably liquid metal, and the liquid metal can provide good heat conducting effect for the foam. When the battery pack heats to a certain extent, the heated temperature of the buffer layer exceeds the melting point range of the liquid metal, the liquid metal in the pores inside the buffer layer is heated to be changed into a flowing state, so that the pores inside the foam can be further filled, and the heat conducting property of the buffer layer is improved.
Drawings
Fig. 1 is a schematic cross-sectional view of a graphite heat conduction assembly in example 1 of the present application.
Fig. 2 is a schematic cross-sectional view of a graphite heat conduction assembly in example 2 of the present application.
Reference numerals illustrate: 1. a heat conducting layer; 2. a buffer layer; 21. a foam layer; 22. a graphite sheet; 3. and a guide hole.
Detailed Description
The application will be described in further detail with reference to the accompanying drawings and specific examples. In the following examples, no specific details are set forth, and the examples were conducted under conventional conditions or conditions recommended by the manufacturer; the raw materials used in the following examples were all commercially available from ordinary sources except for the specific descriptions.
Example 1
The graphite heat conduction assembly comprises two layers of graphite heat conduction layers 1, a buffer layer 2 is fixedly bonded between the two layers of graphite heat conduction layers 1, the thickness of the graphite heat conduction layers 1 is 2 mm, and the thickness of the buffer layer 2 is 15 mm. The buffer layer 2 is made of polyurethane foam with the internal porosity of 45%, and the internal pores of the foam are filled with heat-conducting filler which is liquid metal; a plurality of guide holes 3 distributed in an array are formed in the buffer layer in a penetrating mode, the aperture of each guide hole 3 is 2 mm, the center-to-center distance between every two adjacent guide holes 3 is 10 mm, and the guide holes 3 are filled with heat conducting slurry. The specific preparation method of the graphite heat conduction component comprises the following steps:
s1, cutting foam cotton into specified sizes, and then cutting guide holes on the foam cotton;
s2, uniformly spraying a layer of epoxy resin adhesive on four sides of the foam cotton, which are parallel to the axial direction of the guide hole, and forming an edge sealing layer after the adhesive is cured, wherein the thickness of the edge sealing layer is 15+/-2 mu m;
s3, heating the gallium-indium alloy with the melting point of 55 ℃ to a flowing state, soaking the foam cotton in the gallium-indium alloy, vacuumizing and pressurizing to fill liquid metal in the pores inside the foam cotton, taking out, cleaning the liquid metal outside the foam cotton, and cooling at normal temperature to solidify the liquid metal;
s4, mixing and preparing 25wt% of graphite powder, 70wt% of polyurethane and 5wt% of sodium dodecyl sulfate according to a proportion to obtain heat-conducting paste, stacking foam cotton on the graphite heat-conducting strips, injecting the heat-conducting paste into the guide holes, guiding Kong Weiyi by micro-overflow of the heat-conducting paste, stacking another layer of graphite heat-conducting strips on the foam cotton to cover the other end of the guide holes, compressing the foam cotton when pressure is applied to the upper layer of graphite heat-conducting strips, wherein the compression is 5%, heating to solidify the heat-conducting paste, and obtaining the graphite heat-conducting assembly after solidification.
Comparative example 1
A graphite heat conduction assembly is different from embodiment 1 in that no guide holes are arranged on a buffer layer, and the rest is the same as embodiment 1.
Comparative example 2
A graphite heat conduction assembly is different from the embodiment 1 in that the pores inside the foam are not filled with heat conduction filler, and the rest is the same as the embodiment 1.
Comparative example 3
A graphite heat conduction assembly was different from example 1 in that no buffer layer was provided, and the rest was the same as example 1.
Comparative example 4
A thermally conductive assembly differs from example 1 in that no graphite thermally conductive layer is provided, the remainder remaining consistent with example 1.
And (3) performance detection: the samples prepared in example 1 and comparative examples 1 to 4 were tested for heat conductive property and compression resilience property, and the test results are shown in table 1 below.
Detecting items:
thermal conductivity: the thermal conductivity of the sample was tested according to ASTM D5470 standard;
rebound performance: rebound according to ASTM D575-91;
compressibility properties: samples were compressed, the change in volume before and after complete compression was measured and the compression rate was calculated, compression rate = (original volume-compressed volume)/original volume 100%.
Table 1: example 1 and comparative examples 1 to 4 results of Performance test
Coefficient of thermal conductivity (W/(m.k)) Rebound Rate (%) Compression ratio (%)
Example 1 156.2 81.3 42.7
Comparative example 1 83.9 66.8 62.1
Comparative example 2 58.5 77.3 46.9
Comparative example 3 189.9 87.4 5.4
Comparative example 4 25.2 77.4 45.9
As can be seen from the data in table 1, the graphite heat conduction component provided by the technical scheme of the application combines the excellent heat conduction effect of the graphite heat conduction sheet and the good compression retraction elasticity of the foam cotton, can provide good heat conduction performance and buffering characteristic for the graphite heat conduction component, can provide good heat dissipation effect for the battery pack, and can also protect the battery pack to a certain extent and reduce the damage influence of vibration and slight collision on the battery pack.
It can be seen from the detection data of comparative examples 1 to 4 that the heat conducting filler of China in the foam and the heat conducting slurry in the guide holes both make great contribution to the heat conducting performance of the buffer layer, so that the porosity in the foam can be effectively reduced, the air thermal resistance is reduced, and the buffer layer has a better heat conducting effect.
The following examples further explore graphite thermally conductive assemblies based on example 1.
Example 2
The graphite heat conduction assembly is different from example 1 in that the buffer layer 2 is made of a plurality of graphite sheets 22 and foam cotton layers 21 which are stacked in sequence, and the rest is consistent with example 1, and the specific preparation method is as follows:
s1, cutting foam cotton into specified sizes, cutting a guide hole on the foam cotton, uniformly spraying a layer of epoxy resin adhesive on four sides of the foam cotton parallel to the axial direction of the guide hole, forming an edge sealing layer after the adhesive is solidified, and cutting the foam cotton into specified thickness, wherein the cutting direction is perpendicular to the axial direction of the guide hole;
s2, soaking the foam cotton in liquid metal heated to a flowing state, vacuumizing and pressurizing to fill the liquid metal in the pores inside the foam cotton, taking out, cleaning the liquid metal outside the foam cotton, and cooling at normal temperature to solidify the liquid metal;
s3, sequentially stacking the foam cotton and the graphite sheets in a mould to a specified thickness to obtain a buffer layer; wherein the thickness of the single-layer foam cotton is 2 mm, and the thickness of the graphite sheet is 1 mm;
s4, placing the buffer layer on the graphite heat conducting strip, injecting the heat conducting slurry into the guide hole, slightly overflowing the heat conducting slurry to guide Kong Weiyi, stacking another layer of graphite heat conducting strip on the foam cotton to cover the other end of the guide hole, compressing the foam cotton when pressure is applied to the upper layer of graphite heat conducting strip, wherein the compression amount is 5%, and heating to solidify the heat conducting slurry, so that the graphite heat conducting component is obtained after solidification.
Example 3
A graphite heat conduction assembly is different from the embodiment 2 in that the thickness of single-layer foam is 5 mm, the thickness of a graphite sheet is 3 mm, and the rest is consistent with the embodiment 2.
Example 4
A graphite heat conduction assembly is different from the embodiment 2 in that the thickness of single-layer foam is 3 mm, the thickness of a graphite sheet is 1.5 mm, and the rest is consistent with the embodiment 2.
The samples of examples 2 to 4 were subjected to performance tests, and the test results are shown in Table 2 below.
Table 2: examples 2 to 4 Performance test results
Coefficient of thermal conductivity (W/(m.k)) Rebound Rate (%) Compression ratio (%)
Example 2 178.3 89.6 50.7
Example 3 168.9 80.4 38.1
Example 4 195.5 88.2 43.9
In embodiments 2 to 4, the buffer layer in the graphite heat conduction component is arranged in multiple layers, and it can be seen that the air thermal resistance in the buffer layer is further reduced by the graphite sheets and the foam cotton which are arranged in a laminated manner, so that the heat conduction efficiency is higher, and the heat conduction coefficient of the graphite heat conduction component is obviously increased. After the buffer layer lamination is arranged, the compression retraction elasticity of the graphite heat conduction assembly is further improved, and the buffer effect is better.
Example 5
A graphite heat conduction assembly is different from the embodiment 2 in that gallium-tin alloy is adopted as liquid metal, and the rest is the same as the embodiment 2.
Example 6
The graphite heat conduction assembly is different from the embodiment 2 in that the proportion of the heat conduction slurry is as follows: 40wt% of graphite powder, 50wt% of binder, 10wt% of dispersant and the balance of the graphite powder were the same as in example 2.
Example 7
A graphite heat conduction assembly is different from example 8 in that the binder in the heat conduction paste is acrylic resin, and the rest is the same as example 8.
Example 8
A graphite heat conduction assembly is different from example 2 in that the foam cotton is polyethylene foam cotton, and the rest is the same as example 3.
Example 9
A graphite heat conduction assembly is different from the embodiment 2 in that the foam cotton is silica gel foam cotton, and the rest is the same as the embodiment 3.
Example 10
A graphite heat conduction assembly was different from example 2 in that the porosity of the foam was 60%, and the rest was the same as in example 2.
Example 11
A graphite heat conduction assembly was different from example 2 in that the porosity of the foam was 30%, and the rest was the same as in example 2.
Example 12
A graphite heat conduction assembly was different from example 2 in that the porosity of the foam was 70%, and the rest was the same as in example 2.
The graphite heat conductive assembly samples of examples 5 to 12 were subjected to performance test, and the test results are shown in table 3 below.
Table 3: examples 5 to 9 Performance test results
Coefficient of thermal conductivity (W/(m.k)) Rebound Rate (%) Compression ratio (%)
Example 5 177.6 88.9 50.8
Example 6 185.7 89.1 51.1
Example 7 182.6 89.3 50.4
Example 8 175.4 86.9 51.3
Example 9 181.0 89.7 51.9
Example 10 189.4 85.2 46.3
Example 11 152.9 80.1 39.1
Example 12 196.5 72.4 31.8
Further investigation was made into the raw materials of the graphite heat conduction assembly in examples 5 to 12. In examples 9 to 12, the porosity of the foam was variously adjusted, and it can be seen that when the porosity of the foam was in the range of 45 to 60%, the thermal insulation coefficient and compression resilience of the graphite heat conductive member were both maintained at a high level, and when the porosity of the foam was less than 45%, the heat conductive property was reduced due to the reduction in the content of the heat conductive filler filled in the buffer layer, and the rebound and compression properties were also affected to some extent; and when the porosity of the foam cotton exceeds 60%, the heat conducting filler filled in the foam cotton is too much, so that the compression retraction elasticity of the buffer layer can be obviously influenced, and the buffer effect of the graphite heat conducting component is further influenced.
Example 13
The graphite heat conduction assembly is different from embodiment 1 in that the aperture of the guide holes is 6 mm, the center-to-center distance between the adjacent guide holes is 20 mm, and the rest is the same as embodiment 1.
Example 14
A graphite heat conduction assembly is different from embodiment 1 in that the aperture of a guide hole is 5 mm, the center-to-center distance between adjacent guide holes is 15 mm, and the rest is consistent with embodiment 1.
Example 15
The graphite heat conduction assembly is different from embodiment 1 in that the aperture of the guide holes is 8 mm, the center-to-center distance between the adjacent guide holes is 25 mm, and the rest is consistent with embodiment 1.
Example 16
A graphite heat conduction assembly is different from embodiment 1 in that the aperture of a guide hole is 1 mm, the center-to-center distance between adjacent guide holes is 5 mm, and the rest is consistent with embodiment 1.
Example 17
The graphite heat block was different from example 1 in that the thickness of the buffer layer was 30 mm, the thickness of the graphite heat conductive layer was 5 mm, and the balance was kept the same as example 1.
Example 18
The graphite heat block was different from example 1 in that the thickness of the buffer layer was 20 mm, the thickness of the graphite heat conductive layer was 3 mm, and the balance was kept the same as example 1.
The samples of examples 13 to 16 were subjected to performance tests, and the test results are shown in Table 4 below.
Table 4: results of Performance measurements of examples 13 to 18
Coefficient of thermal conductivity (W/(m.k)) Rebound Rate (%) Compression ratio (%)
Example 13 165.5 80.7 44.7
Example 14 166.1 83.3 45.6
Example 15 153.4 70.4 28.7
Example 16 131.7 75.6 21.9
Example 17 161.9 79.4 40.5
Example 18 166.3 82.5 46.2
As can be seen from the data in table 4, when the aperture of the pilot hole and the spacing between the centers of the adjacent pilot holes are defined within the scope of the present application, the thermal conductivity and compression resilience of the graphite thermal conduction assembly can be maintained at the preferred levels. When the diameter of the guide holes is too small/too large and the density of the guide holes is too large/too small, the heat conduction performance and/or compression resilience performance of the graphite heat conduction assembly are reduced.
The above embodiments are not intended to limit the scope of the present application, so: all equivalent changes in structure, shape and principle of the application should be covered in the scope of protection of the application.

Claims (6)

1. The graphite heat conduction assembly is characterized by comprising two graphite heat conduction layers (1), wherein a buffer layer (2) is arranged between the two graphite heat conduction layers (1), a plurality of guide holes (3) are formed in the buffer layer (2) in a penetrating mode, the guide holes (3) are communicated with the two graphite heat conduction layers (1), and heat conduction slurry is filled in the guide holes (3); the buffer layer (2) is made of foam and heat-conducting filler filled in the pores inside the foam;
the buffer layer (2) is composed of a plurality of layers of foam cotton layers (21) and graphite sheets (22) which are stacked in sequence, the heat conducting filler is filled in the inner holes of the foam cotton layers (21), and the guide holes (3) penetrate through the foam cotton layers (21) and the graphite sheets (22); the heat conducting filler is liquid metal;
the heat-conducting slurry consists of the following raw materials in percentage by weight: 25-40% of graphite powder, 50-70% of adhesive and 5-10% of dispersing agent.
2. The graphite heat conduction assembly according to claim 1, wherein the thickness of the single-layer foam layer (21) is 2-5 mm, and the thickness of the graphite sheet (22) is 1-3 mm.
3. The graphite heat transfer assembly of claim 1 wherein the foam wool is any one of polyurethane foam wool, polyethylene foam wool, polyvinyl chloride foam wool, silicone foam wool, and polyimide foam wool.
4. The graphite heat transfer assembly of claim 1 wherein said adhesive is at least one of epoxy, polyurethane, acrylic, silicone.
5. The graphite heat conduction assembly according to claim 1, wherein the aperture of the guide hole (3) is 2-6 mm; the center distance between adjacent guide holes (3) is 10-20 mu m.
6. The method for preparing the graphite heat conduction assembly as claimed in any one of claims 1 to 5, which is characterized by comprising the following steps:
s1, cutting a foam layer (21) into a specified thickness, and then forming a guide hole (3) on the foam layer (21);
s2, spraying a layer of adhesive on the side edges of the foaming cotton layer (21) parallel to the axial direction of the guide hole (3), and forming an edge sealing layer after the adhesive is solidified;
s3, uniformly filling the heat-conducting filler into the inner pores of the foam cotton layer (21), sequentially stacking the foam cotton layer (21) and the graphite sheets (22) which are the same in size and provided with the guide holes (3) to a specified height, and injecting the heat-conducting slurry into the guide holes (3) after stacking is completed to obtain the buffer layer (2);
and S4, pressing the graphite heat conduction layer (1) on two sides of the buffer layer (2) before solidification of the heat conduction slurry, and adhering and fixing the graphite heat conduction layer (1) on the buffer layer (2) after solidification of the heat conduction slurry to obtain the graphite heat conduction assembly.
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