KR102002365B1 - Radiant heat plate for battery cell module and battery cell module comprising the same - Google Patents

Abstract

The present invention relates to a heat dissipating interface plate for a battery cell module having a high thermal conductivity and flexibility and a battery cell module including the heat dissipating interfacial plate. The heat dissipating interface plate is light and excellent in heat radiation effect, Cell stability is excellent.

Description

TECHNICAL FIELD [0001] The present invention relates to a heat dissipation interface plate for a battery cell module and a battery cell module including the same,

The present invention relates to a heat dissipating interface plate for a battery cell module having a high thermal conductivity and flexibility and a battery cell module including the heat dissipating interfacial plate. The heat dissipating interface plate is light and excellent in heat radiation effect, The efficiency is excellent.

The electric vehicle battery generates a local temperature difference or a high temperature due to heat generated due to high output, high speed and repeated charging, thereby causing a thermal runaway phenomenon which hinders the efficiency and stability of the battery. This problem is caused by insufficient heat dissipation and diffusion ability to the outside than heat generated inside the battery.

In order to solve the above problem, a component such as a heat sink for discharging heat is mounted on a battery for an electric vehicle. Aluminum has been conventionally used as a material for heat dissipation parts, but attempts have recently been made to replace aluminum with graphite having excellent thermal diffusion characteristics. However, graphite has a disadvantage in that it is not easy to shape due to its material properties.

On the other hand, the lithium ion battery is used as a power source of a portable electronic device with a cell operating voltage of 3.6 V or higher, or a plurality of cells connected in series to be connected to a high output such as a hybrid electric vehicle (HEV) or a pure electric vehicle It is attracting attention as a power source of environment-friendly vehicles. Such a lithium ion battery can be manufactured in various forms, and in case of a pouch type battery cell which is widely used in recent years, the case itself has a flexibility and is relatively free from the shape.

Such a pouch-type battery cell causes damage to the separator due to expansion of the electrode plate in the battery cell, resulting in an increase in voltage and a reduction in the final battery capacity as well as generation of internal resistance. Therefore, An interfacial plate (a member positioned between the cell and the cell of the battery) is required. The heat dissipating interface plates should have excellent elasticity and heat radiation performance of the material that can cope with the volume change of the battery cell.

Conventional heat dissipating interface plates include metal members such as aluminum and have excellent heat dissipation efficiency (see Korean Patent Publication No. 2013-0091506).

Korea Patent Publication No. 2013-0091506

However, since the conventional heat dissipating interface plate includes a metal member such as aluminum, it does not meet the recent trend of becoming thinner and thinner, and there is a limit to effectively dissipate heat generated from a pouch-type battery due to heat anisotropy and low heat conduction.

Accordingly, it is an object of the present invention to provide a heat dissipating interface plate for a battery cell module including a graphite sheet, which is light in weight, has excellent thermal conductivity and flexibility, and a battery cell module including the same.

In order to achieve the above object,

A thermally conductive layer and a buffer layer formed on one surface of the thermally conductive layer,

Wherein the thermally conductive layer comprises a graphite sheet,

Wherein the buffer layer comprises a polymer resin,

There is provided a heat radiation interface plate for a battery cell module, wherein the graphite sheet has a surface structure in the form of a fabric in which weft and warp are woven.

According to another embodiment,

A plurality of battery cells; A heat dissipation interface plate inserted between battery cells; And a heat sink coupled to the heat dissipation interface plate,

Wherein the heat dissipation interface plate includes a thermally conductive layer and a buffer layer formed on one surface of the thermally conductive layer, the thermally conductive layer includes a graphite sheet, the buffer layer includes a polymer resin,

Wherein the graphite sheet has a surface structure in the form of a fabric in which weft and warp are woven.

The heat dissipation interface plate for a battery cell module according to the embodiment includes a graphite sheet and a polymer resin, and is lighter than a metal material, and has excellent thermal conductivity and flexibility. In addition, the battery cell module including the heat dissipation interface plate has an advantage of excellent heat dissipation efficiency, which improves battery efficiency and enables continuous temperature management.

1 is a schematic view of the surface of a graphite sheet of one embodiment.
2 is a photograph of a surface of a graphite sheet according to one embodiment.
3 is a photograph of the surface of the graphite sheet according to one embodiment observed with an atomic force microscope (AFM).
4 and 5 are schematic diagrams of a battery cell module according to an embodiment.
6 and 7 are cross-sectional views of a battery cell module according to an embodiment.

The heat dissipation interface plates for the battery cell module of the embodiment

A thermally conductive layer and a buffer layer formed on one surface of the thermally conductive layer,

Wherein the thermally conductive layer comprises a graphite sheet,

Wherein the buffer layer comprises a polymer resin,

The graphite sheet has a surface structure in the form of a fabric in which weft and warp are woven.

Heat conduction layer

When the heat conduction layer includes a graphite sheet, it is possible to provide a heat dissipating interface plate which is lighter than the heat dissipation interface plate including a metal material, has excellent heat dissipation effect, and is excellent in flexibility and excellent in workability.

The graphite sheet has a surface structure in the form of a fabric in which weft and warp are woven. In particular, the graphite sheet may comprise an inner layer comprising graphitized fibers and an outer graphite layer. More specifically, the graphite sheet may comprise an inner layer comprising graphitized fibers and a graphite outer layer covering either or both surfaces of the inner layer.

The surface structure of the graphite sheet may be the same as the surface of the fibers constituting the inner layer. The fiber may be a woven base material, and the surface structure of the graphite sheet produced using the fiber base material may have a structure as described above.

The inner layer may comprise a fiber bundle comprising a plurality of graphite fibers. Specifically, the inner layer may be composed of a fiber bundle containing a plurality of graphite fibers. In addition, the fiber bundle may include voids formed between a plurality of graphite fibers. Further, the inner layer may comprise a weft and warp-woven fabric form consisting of graphite fibers or graphite fiber bundles.

The inner layer may comprise natural fibers or graphitized fibers. Specifically, the inner layer may be natural fibers or synthetic fibers that are carbonized and graphitized.

The natural fibers may be at least one selected from the group consisting of cellulose fibers, protein fibers and mineral fibers. The cellulose fibers may be, for example, (i) seed fibers such as cotton or kerosene, (ii) stem fibers such as flax, jute, hemp or jute, (iii) Leaf fibers such as Manila hemp, Abaca or Sisalma. The protein fiber may be, for example, (i) wool fiber, (ii) silk fiber and (iii) hair fiber. The mineral fibers include, for example, artificial mineral fibers such as (i) glass wool and minerals, and (ii) fiberized liquefied glass, rock and other minerals at high temperatures. Specifically, the natural fiber may include at least one member selected from the group consisting of cotton, hemp, wool, and silk.

The man-made fibers may be at least one selected from the group consisting of organic fibers and inorganic fibers. The organic fibers may be, for example, (i) cellulose-based fibers such as rayon, tencel (lyocell), modal and the like, or regenerated fibers containing protein-based fibers, (ii) cellulose fibers such as acetate, triacetate, Based fibers, polyvinyl alcohol-based fibers, polyvinyl alcohol-based fibers, acrylic fibers or polypropylene fibers, or (iii) semisynthetic fibers including polyamide fibers, polyester fibers, polyurethane fibers, polyethylene fibers, And synthetic fibers such as synthetic fibers. Specifically, the synthetic fiber may be at least one synthetic fiber selected from the group consisting of nylon, polyester, polyurethane, polyethylene, polyvinyl chloride, polyfluoroethylene, polyvinyl alcohol, acrylic and polypropylene; Or at least one cellulosic fiber selected from the group consisting of rayon, acetate, and triacetate.

For example, the inner layer may comprise a lattice structure with a pitch of 20 to 200 mu m and a width of 60 to 200 mu m.

The graphite outer layer may cover either or both surfaces of the inner layer. Specifically, the graphite outer layer is composed of a first graphite outer layer coated on one surface of the graphite inner layer and a second graphite outer layer coated on the other surface of the graphite inner layer, and a part of the first graphite outer layer and the second graphite outer layer Can be connected.

The graphite outer layer may be one in which the polymer resin is graphitized. In addition, the graphite outer layer may comprise natural graphite or expanded graphite.

The polymer resin may include at least one member selected from the group consisting of polyimide, polyamic acid, polyvinyl chloride, polyester, polyurethane, polyethylene, polyfluoroethylene, polyvinyl alcohol, acrylic and polypropylene. Specifically, the polymer resin may include at least one member selected from the group consisting of polyimide, polyamic acid and polyvinyl chloride having a weight average molecular weight of 200,000 to 300,000 g / mol.

Specifically, the graphite sheet may be produced by producing a laminate including a fibrous base material and a polymer coating layer on one side or both sides of the fibrous base material, and then carbonizing and graphitizing the laminate as one body. By carrying out the process of carbonization and graphitization at a predetermined temperature, the fiber base material and the polymer coating layer constituting the laminate are both graphitized, whereby a graphite sheet can be produced.

When the graphite sheet is produced by graphitizing a laminate as described above, there is an advantage that a graphite sheet having a relatively thick thickness and excellent thermal conductivity can be produced at low cost.

At this time, the thickness of one polymer coating layer may be 30 탆 to 50 탆. For example, when the polymer coating layer is formed on both surfaces of the fiber substrate, the total thickness of the polymer coating layer may be 60 to 100 탆. When the thickness of the polymer coating layer is formed within the above-mentioned thickness range, the laminate may be exposed on the surface of the graphite sheet after carbonization and graphitization, and a weaving structure derived from the fiber base material.

The fibrous base material may be at least one selected from the group consisting of natural fibers and man-made fibers. The natural fibers and the synthetic fibers are as described for the inner layer.

The polymer coating layer is as described for the polymer resin of the graphite outer layer.

In addition, the graphite sheet may have a lattice structure with a pitch of 20 to 200 mu m and a width of 60 to 200 mu m.

Referring to FIGS. 1 and 2, the graphite sheet may have a surface structure in the form of a fabric in which weft and warp are woven.

The warp yarns A and the warp yarns B may have widths d1 and d2 of 20 mu m to 200 mu m, 30 mu m to 170 mu m, or 50 mu m to 170 mu m, respectively. In addition, the weft (A) and the warp (B) may have pitches (P1 and P2) of 20 탆 to 200 탆, 30 탆 to 170 탆, or 50 탆 to 170 탆, respectively.

Also, the surface structure of the graphite sheet may satisfy a warp (A) × warp (B) of 80 to 130 × 100 to 150 count / inch. For example, the surface structure of the graphite sheet can satisfy 130 × 150 counts / inch, 100 × 120 counts / inch, or 80 × 100 counts / inch of warp (A) × warp (B).

The graphite sheet may have a predetermined surface roughness by having the surface structure described above. Specifically, referring to FIG. 1, the surface of the graphite sheet has a step between a portion (C) where the weft (A) and the warp (B) overlap and a portion (D) that is not overlapped.

Specifically, the graphite sheet may have a surface roughness Ra of 0.5 탆 to 10 탆 (see Fig. 3). More specifically, the graphite sheet may have a surface roughness (Ra) of 1 탆 to 8 탆, or 2 탆 to 6 탆.

The graphite sheet may have an average thickness of 10 to 500 m. Specifically, the graphite sheet may have an average thickness of 50 탆 to 500 탆, 70 탆 to 500 탆, 70 탆 to 300 탆, 10 탆 to 300 탆, 10 탆 to 250 탆, or 70 to 250 탆. When the thickness of the graphite sheet is within the above range, it may be advantageous in terms of heat capacity.

The graphite sheet may have a vertical thermal conductivity of 1 to 20 W / m · K and a horizontal thermal conductivity of 800 to 2,000 W / m · K. Specifically, the graphite sheet has a vertical thermal conductivity of 1 to 15 W / mK, 1 to 10 W / mK, or 5 to 10 W / mK, a horizontal thermal conductivity of 900 to 2,000 W / m · K, 1,000 to 1,800 W / m · K, or 1,200 to 1,800 W / m · K.

As a result of the MIT bending test conducted under conditions of a curvature radius (R) of 5 mm, a bending angle of 180 degrees, a load of 0.98 N, and a bending speed of 90 revolutions per minute, the graphite sheet had a number of bending cycles . Specifically, the graphite sheet may have 10,000 to 20,000 cycles, 10,000 to 18,000 cycles, or 10,000 to 15,000 cycles as a result of the MIT flexural test.

The graphite sheet may have a specific heat of 0.5 to 1.0 J / g · K, 0.5 to 0.9 J / g · K, 0.6 to 0.9 J / g · K, or 0.7 to 0.9 J / g · K at 50 ° C. The graphite sheet may have a density of 0.5 to 2.5 g / cm 3, 0.5 to 2.0 g / cm 3, or 0.8 to 2.0 g / cm 3.

Buffer layer

The buffer layer may include a polymer resin. Specifically, the buffer layer may include a vinyl-based polymer.

The vinyl-based polymer may include at least one member selected from the group consisting of polyvinyl butyral and ethylene-vinyl acetate. Specifically, the vinyl-based polymer may be polyvinyl butyral or ethylene-vinyl acetate.

The polymer resin may have a weight average molecular weight of 100,000 to 500,000 g / mol, 100,000 to 300,000 g / mol, or 100,000 to 200,000 g / mol.

The thickness of the buffer layer may be 10 to 100 mu m, 10 to 70 mu m, or 10 to 30 mu m. When the thickness of the buffer layer is within the above range, shrinkage and expansion occurring during charging and discharging of the battery cell can be buffered to improve the stability of the battery.

The buffer layer may have a coefficient of thermal expansion of 0.1 to 0.5 ppm / 占 폚 at 0 to 50 占 폚 and a dynamic storage modulus of 1 占⁰⁶ to 3 占⁰⁷ Pa at a temperature of 20 占 폚 and a frequency of 50 to 100 Hz. Specifically, the buffer layer has a coefficient of thermal expansion of 0.1 to 0.3 ppm / 占 폚 or 0.15 to 0.3 ppm / 占 폚 at 0 to 50 占 폚, a dynamic storage modulus at a temperature of 20 占 폚 and a frequency of 50 to 100 Hz of 1 占⁰⁶ 2 may be a × 10 ⁷ Pa, or 1 × 10 ⁶ to 5 × 10 ⁶ Pa.

The buffer layer may have a tensile strength of 10 to 50 MPa, 10 to 40 MPa, or 10 to 30 MPa, and the elongation at break may be 150 to 400%, 150 to 350%, or 200 to 300%. The buffer layer may have a thermal conductivity of 0.01 to 0.8 W / mK, 0.1 to 0.8 W / mK, 0.1 to 0.6 W / mK, or 0.1 to 0.5 W / mK.

The tensile strength and the elongation at break may be those measured by the method described in JIS K 6771. In addition, the thermal conductivity may be measured by the method described in ASTM F 433.

The thermally conductive layer and the buffer layer may be bonded by heating and pressing so that there is no physical boundary between the layers. The heating and pressurization can be heated to 100 to 150 ° C and pressurized to 0.1 to 0.5 MPa.

The heat dissipation interface plate may have an average thickness of 20 to 200 탆 and a thickness expansion rate calculated by the following equation 1: 1 to 5%. Specifically, the heat dissipation interface plate has an average thickness of 50 to 100 탆, and a thickness expansion ratio calculated by Equation (1) may be 1 to 3%.

[Equation 1]

In the above equation (1)

The thickness of the initial plate is the thickness of the plate measured at 25 占 폚,

The thickness of the expanded plate is the thickness of the plate measured at 80 占 폚.

Battery cell module

The battery cell module of another embodiment

A plurality of battery cells; A heat dissipation interface plate inserted between battery cells; And a heat sink coupled to the heat dissipation interface plate,

Wherein the heat dissipation interface plate includes a thermally conductive layer and a buffer layer formed on one surface of the thermally conductive layer, the thermally conductive layer includes a graphite sheet, the buffer layer includes a polymer resin,

The graphite sheet has a surface structure in the form of a fabric in which weft and warp are woven.

Referring to FIG. 4, the battery cell module A of the embodiment includes a plurality of battery cells 100; A heat dissipation interface plate (200) inserted between battery cells; And a heat sink 300 coupled with the heat dissipation interface plate. At this time, the heat sink may be used as a channel for the cooling water 400 or the cooling air 400.

The heat dissipation interface plate, the heat conduction layer, and the buffer layer are as described for the heat dissipation interface plate for the battery cell module.

The heat dissipation interface plate may be bent in a lattice shape and a bent one side of the heat dissipation interface plate may be coupled to the heat sink.

Specifically, the connection may be formed by forming a through-hole on one side of the heat-dissipating interface plate and the heat sink,

In addition, the battery cell module may include an additional metal layer. Specifically, the battery cell module includes an additional metal layer, and after the through hole is formed so that the heat sink, the bent surface of the heat dissipating interface plate, and the additional metal layer are laminated in order, .

Alternatively, the heat sink may be coupled to the bent one side of the heat dissipation interface plate through a thermally conductive adhesive.

5, the heat-dissipating interface plate 200 is bent in a L-shape, and a bent one side of the heat dissipation interface plate may be coupled to the heat sink 300. [

Referring to FIG. 6, the battery cell module may include the heat sink 300, the bent surface of the heat dissipating interface plate 200, and the additional metal layer 500 in this order.

Referring to FIG. 7, the battery cell module may include a shape in which the bent surface of the heat dissipating interface plate 200 and the heat sink 300 are coupled through the coupling member 600.

The joining member may be a thermally conductive adhesive or bolt. Specifically, when the heat sink, the bent surface of the heat dissipation interface plate, and the additional metal layer are stacked in order, and the through hole is formed, the through hole is coupled through the coupling member, the coupling member may be a bolt. Further, when the bent surface of the heat dissipating interface plate and the heat sink are coupled through the fitting member, the fitting member may be a thermally conductive adhesive.

The thermally conductive adhesive is not particularly limited as long as it is an adhesive commonly used for thermally conductive parts. For example, the thermally conductive adhesive may be a silicone-based, epoxy-based or polyurethane-based thermally conductive adhesive.

A: Battery cell module 100: Battery cell
200: Heat dissipation interface plate 300: Heat sink
400: cooling water or cooling air 500: additional metal layer
600: coupling member

Claims (16)

A thermally conductive layer and a buffer layer formed on one surface of the thermally conductive layer,
Wherein the thermally conductive layer comprises a graphite sheet,
Wherein the buffer layer comprises a polymer resin,
Wherein the graphite sheet has a surface structure in the form of a fabric in which weft and warp are woven,
A heat dissipation interface plate for a battery cell module having a thickness expansion rate of 1 to 3% calculated by the following equation (1)
[Equation 1]

In the above equation (1)
The thickness of the initial plate is the thickness of the plate measured at 25 占 폚,
The thickness of the expanded plate is the thickness of the plate measured at 80 占 폚.
The method according to claim 1,
Wherein the graphite sheet comprises an inner layer comprising graphitized fibers and a graphite outer layer.
The method according to claim 1,
Wherein the graphite sheet has an average thickness of 50 to 500 占 퐉.
The method according to claim 1,
Wherein the graphite sheet has a surface roughness (Ra) of 0.5 占 퐉 to 10 占 퐉.
The method according to claim 1,
Wherein the graphite sheet has a vertical thermal conductivity of 1 to 20 W / m 占, and a horizontal thermal conductivity of 800 to 2,000 W / m 占..
The method according to claim 1,
Wherein the buffer layer has a tensile strength of 10 to 30 MPa, a elongation at break of 200 to 300%, and a thermal conductivity of 0.1 to 0.5 W / m · K.
The method according to claim 1,
Wherein the buffer layer has a thermal expansion coefficient of 0.1 to 0.3 ppm / 占 폚 at 0 to 50 占 폚 and a dynamic storage modulus of 1 占⁰⁶ to 3 占⁰⁷ Pa at a temperature of 20 占 폚 and a frequency of 50 to 100 Hz. Heat dissipation interface plate.
The method according to claim 1,
Wherein the buffer layer comprises a vinyl-based polymer.
The method according to claim 1,
Wherein the heat conduction layer and the buffer layer are bonded by heating and pressing so that there is no physical boundary between the layers.
The method according to claim 1,
Wherein the heat radiation interface plate has an average thickness of 50 to 100 占 퐉.
A thermally conductive layer and a buffer layer formed on one surface of the thermally conductive layer,
Wherein the thermally conductive layer comprises a graphite sheet,
Wherein the buffer layer comprises a polymer resin,
Wherein the graphite sheet has a surface structure in the form of a fabric in which weft and warp are woven,
Wherein the graphite sheet has a lattice structure with a surface structure of 20 to 200 mu m in pitch and 60 to 200 mu m in width.
A plurality of battery cells; A heat dissipation interface plate inserted between battery cells; And a heat sink coupled to the heat dissipation interface plate,
Wherein the heat dissipation interface plate includes a thermally conductive layer and a buffer layer formed on one surface of the thermally conductive layer, the thermally conductive layer includes a graphite sheet, the buffer layer includes a polymer resin,
Wherein the graphite sheet has a surface structure in the form of a fabric in which weft and warp are woven,
A battery cell module having a thickness expansion rate calculated by the following formula (1): 1 to 3%
[Equation 1]

In the above equation (1)
The thickness of the initial plate is the thickness of the plate measured at 25 占 폚,
The thickness of the expanded plate is the thickness of the plate measured at 80 占 폚.
13. The method of claim 12,
The heat dissipation interface plates are bent in a lattice shape,
And a bent one side of the heat dissipation interface plate is coupled to the heat sink.
14. The method of claim 13,
Wherein the coupling is formed on one side of the heat-dissipating interface plate and on one side of the heat sink, the through-hole being in contact with the heat-dissipating interface plate, and then joined through the coupling member.
15. The method of claim 14,
Wherein the battery cell module comprises an additional metal layer,
Wherein the through hole is formed so that the heat sink, the bent surface of the heat dissipation interface plate, and the additional metal layer are stacked in order, and then joined through the coupling member.
14. The method of claim 13,
And the heat sink is coupled to the bent one side of the heat dissipation interface plate through the thermally conductive adhesive.

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