KR101789293B1 - Battery pack of improved reaction capability to cell temperature rise and fabricating method for the same - Google Patents

Abstract

A battery pack having improved cell temperature rise responsiveness is provided. A battery pack according to the present invention includes: a cell laminate in which a plurality of cells are stacked; And a cooling device for cooling the cells, including a member positioned between the stacked cells, wherein the member comprises a unidirectional thermally deformable material portion. According to the present invention, the air flow rate or endothermic volume is quickly adjusted to the cell temperature in the battery pack which changes frequently, so that proper cooling is achieved. Therefore, the cell temperature rise can be effectively suppressed, and the performance and lifetime of the battery can be improved.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a battery pack,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a modular battery pack in which secondary battery unit cells are stacked, and a method of manufacturing the same. More particularly, the present invention relates to a battery pack including a variable cooling device.

Unlike a primary battery, which can not be recharged, a secondary battery refers to a battery capable of charging and discharging, and is used in various fields such as an energy storage system (ESS), an electric vehicle (EV), And is used as a power source for a hybrid vehicle (HEV).

Generally, a large-capacity modular battery pack constructed by stacking a plurality of high-output cells and connecting them in series is generally used for devices requiring large power such as motor drive of an electric vehicle. For example, in the case of an HEV battery pack, several to several tens of cells are alternately charged and discharged, so that it is necessary to control such charging / discharging so as to maintain the battery pack in an appropriate operating state.

In particular, the heat generated during operation of the secondary battery raises the temperature of the secondary battery, and if the heat is not efficiently cooled, the lifetime of the secondary battery is shortened and malfunctions are caused, Which is an important issue in manufacturing a battery pack including a battery.

The battery pack stacks adjacent cells at regular intervals so as to remove heat generated during charging and discharging. For example, the cells themselves may be sequentially stacked while spaced apart from each other by a predetermined space, or in the case of a cell having low mechanical rigidity, one or a combination of two or more cells may be stacked in a cartridge, . ≪ / RTI > The stacked cells are structured such that a flow path of a coolant such as cooling water or cooling air is formed so as to effectively remove accumulated heat.

For example, in the case of a direct air-cooling module, there is a flow path through which cooling air can flow between the cell and the cell. Generally, a cooling fan is used to provide cooling air. The cell temperature in the battery pack varies from time to time depending on the operating conditions, but the problem of very slow response to temperature changes, especially temperature rises, is due to cooling control being only on / off control of the cooling fan have.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a battery pack and a method of manufacturing the same that have improved cell temperature rising capability in a battery pack.

According to an aspect of the present invention, there is provided a battery pack comprising: a cell stacked body in which a plurality of cells are stacked; And a cooling device for cooling the cells, including a member positioned between the stacked cells, wherein the member comprises a unidirectional thermally deformable material portion.

According to one embodiment, the member provides an air flow path between the stacked cells, and the air flow path is defined as a space between the unidirectional heat deformable material portions. In this case, the unidirectional thermally deformable material part thermally expands along the stacking direction of the cells when the temperature of the cells rises, thereby increasing the height of the air flow path, or increasing the height of the air flow path in a direction perpendicular to the stacking direction of the cells So as to increase the width of the air flow path.

According to another embodiment, the member is a cooling fin that absorbs heat in face-to-face contact with the cells and is made of the unidirectional heat-deformable material portion. In this case, the unidirectional thermally deformable material portion may thermally expand along the stacking direction of the cells when the temperatures of the cells rise, thereby increasing the cross-sectional area of the heat releasing path by conduction.

In the present invention, the unidirectional heat-deformable material portion may be any one of plastics, polymers, oligomers, derivatives thereof, or combinations thereof.

As one example, the unidirectional thermally deformable material portion comprises polyester or derivatives thereof.

In order to solve the above problems, the present invention also provides a method of manufacturing such a battery pack. According to this battery pack manufacturing method, by configuring the member so as to include the unidirectional heat-deformable material portion, the cooling device can be changed in accordance with the deformation of the unidirectional heat-deformable material portion when the cell temperature rises, thereby cooling the cell.

Since the secondary battery is used for a long period of time through charging and discharging, not only the period of use but also the stability of the battery is of great interest. In addition, since the battery pack generates high heat during charging and discharging, it affects the performance and lifetime of the battery, so it is necessary to form an appropriate cooling system to cool the battery pack.

According to the present invention, a material which uni-directionally expands or shrinks in a single direction is inserted between a cell and a cell so that when the cell temperature rises, the material expands in a height direction or shrinks in a width direction so that more cooling air can be introduced, And when the cell temperature falls, it contracts or expands to return to its original state.

Accordingly, the air flow rate or the endothermic volume is quickly adjusted to the cell temperature in the battery pack which changes from time to time, so that proper cooling is achieved. Therefore, the cell temperature rise can be effectively suppressed, and the performance and lifetime of the battery can be improved.

According to the present invention, since the cooling device is variable, the air flow rate can be controlled at a high reaction rate or the endothermic volume can be controlled, so that the temperature variation width of the cell can be reduced under the same operating condition.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments of the invention and, together with the description of the invention, It should not be construed as limited.
1 is a perspective view illustrating a battery pack according to an embodiment of the present invention.
2 is a perspective view showing only a cell stack portion in the battery pack of FIG. 1
Fig. 3 shows only two cell portions in a cross section of the cell pack in Fig. 1 that are parallel to the stacking direction of the cell stack, and is an example of a case where the unidirectional thermal deformation additive material thermally expands along the stacking direction y of the cells.
FIG. 4 is a cross-sectional view of the cell stack of the battery pack of FIG. 1, showing only two cell portions of the cell stack in a direction parallel to the direction of stacking. Yes.
FIG. 5 is a perspective view of a battery pack according to another embodiment of the present invention, and FIG. 6 is a front view.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. It is provided to let you know. It should be noted that the embodiments described in the present specification and the configurations shown in the drawings are only the most preferred embodiments of the present invention and are not intended to represent all of the technical ideas of the present invention so that various equivalents And variations are possible.

1 is a perspective view illustrating a battery pack according to an embodiment of the present invention.

Referring to FIG. 1, a battery pack 100 according to an embodiment of the present invention includes a cell stack 30, an intake duct 40, and an exhaust duct 50.

The cell stack 30 is formed by stacking a plurality of cells 20. The cell 20 includes an electrode assembly composed of a positive electrode plate, a separator, and a negative electrode plate. The positive electrode plate and the negative electrode lead of each cell 20 are electrically connected to a plurality of positive electrode tabs and negative electrode tabs protruding from the negative electrode plate, .

As the material of the positive electrode plate, aluminum is mainly used. Alternatively, the positive electrode plate may be formed by surface-treating a surface of stainless steel, nickel, titanium or aluminum or stainless steel with carbon, nickel, titanium, silver or the like. Further, if the secondary battery is made of a material having high conductivity without causing a chemical change, there is no limitation to use it as a positive electrode plate.

A positive electrode tab may be provided on a part of the positive electrode plate, and the positive electrode tab may be formed to extend the positive electrode plate. Alternatively, it is also possible to form a configuration in which a member made of a conductive material is joined to a predetermined portion of the positive electrode plate through welding or the like. Further, the positive electrode material may be applied and dried on a part of the outer surface of the positive electrode plate to form the positive electrode tab.

The negative electrode plate corresponding to the positive electrode plate is mainly made of a copper material. Alternatively, the cathode plate may be a surface treated with carbon, nickel, titanium or silver on the surface of stainless steel, aluminum, nickel, titanium, copper or stainless steel, and aluminum-cadmium alloy or the like may be used.

The negative electrode plate may also be provided with a negative electrode tab in a certain area and may be formed to extend from the negative electrode plate as in the positive electrode tab described above. In addition, the negative electrode plate may be formed by welding a conductive member to a predetermined portion of the negative electrode plate Or it may be formed in such a manner that a negative electrode material is applied and dried on a part of the outer circumferential surface of the negative electrode plate.

The positive electrode lead is electrically connected to the positive electrode tab provided on the positive electrode plate, and the negative electrode lead is electrically connected to the negative electrode tab provided on the negative electrode plate. Preferably, the positive electrode lead and the negative electrode lead are bonded to a plurality of positive electrode tabs and a plurality of negative electrode tabs, respectively.

The positive electrode plate and the negative electrode plate are respectively coated with a positive electrode active material and a negative electrode active material. LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , LiFePO ₄ or Li _{1 + z} Ni _{1 -xy} Co _x M _y O ₂ (0? 1, 0? y? 1, 0? x + y? 1, 0? z? 1, and M is a metal such as Al, Sr, Mg, La, or Mn). The negative electrode active material is a carbonaceous active material, and examples of the negative electrode active material include a carbon material such as crystalline carbon, amorphous carbon, carbon composite, carbon fiber, lithium metal, lithium alloy and the like. The types and chemical compositions of the cathode active material and the anode active material may vary depending on the kind of the secondary battery. Therefore, it should be understood that the specific examples given above are only examples.

The separation membrane is not particularly limited as long as it has a porous material. The separation membrane may be a porous polymer membrane such as a porous polyolefin membrane, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-trichlorethylene, polymethyl methacrylate, polyacrylonitrile, polyvinyl Polyvinyl pyrrolidone, polyvinyl acetate, ethylene vinyl acetate copolymer, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, cyanoethylpolyvinyl alcohol, cyanoethylcellulose, Polybutylene terephthalate, polybutylene terephthalate, polyester, polyacetal, polyamide, polyether ether ketone, polyether sulfone, polyether sulfone, polyether sulfone, , Poly Alkenylene may be formed of oxide, polyphenylene sulfide, polyethylene naphthalene, a non-woven film, a porous web (web) or a mixture film having a structure like. An inorganic particle may be adhered to an end surface or both surfaces of the separation membrane.

The inorganic particles are preferably inorganic particles having a high dielectric constant of 5 or more, more preferably inorganic particles having a dielectric constant of 10 or more and a low density. This is because it can easily transfer lithium ions moving in the cell. Non-limiting examples of inorganic particles having a high dielectric constant of 5 or more is _{Pb (Zr, Ti) O 3} (PZT), Pb 1 - x La x Zr 1 -y Ti y O 3 (PLZT), Pb (Mg 3 Nb _{2/3) O 3 -PbTiO 3} (PMN-PT), BaTiO 3, HfO 2, SrTiO 3, TiO 2, Al 2 O 3, ZrO 2, SnO 2, CeO 2, MgO, CaO, ZnO, Y 2 O ₃ Or a mixture thereof.

As shown in the figure, each of the cells 20 is arranged in a stacked manner so as to face the adjacent cells while being in a plate-like shape. The cartridges 25 each fix the cells 20 to form a laminated structure.

The cell 20 may be a pouch-shaped battery assembly. At this time, the cell 20 is a pouch-shaped battery cell having a structure in which the outer circumferential surface of the battery case is thermally fused and sealed while the electrode assembly is housed in the battery case of the laminate sheet including the resin layer and the metal layer, And the heat-sealed outer circumferential surface of the cell can be fixed between the cartridges 25 that fix the cells 20 to form a cell laminate.

The intake duct 40 is coupled to the side surface of the cell stack body 30 and allows the cooling air introduced from the outside to be discharged into the cells 20. The intake duct (40) has one side connected to the intake port (45) through which the cooling air flows and the other side opened to the side of the cell stack body (30). The intake duct 40 is inclined so as to decrease in width as the intake duct 45 moves away from the intake port 45.

The exhaust duct 50 is opposed to the intake duct 40 on the other side of the cell stack 30. The cooling air passing between the cells 20 can be discharged to the outside. The exhaust duct 50 has one side connected to the exhaust port 55 through which the cooling air is discharged and the other side opened toward the cell laminate 30. [

It is preferable that the intake duct 40 and the exhaust duct 50 are formed on both sides of the cell stack 30 opposite to each other. This is because the intake port 45 and the exhaust port 55 are formed on different surfaces of the cell stack body 30 so that the plurality of cells 20 are cooled by being sucked into the intake port 45 and passing through the cell stack body 30 So that the cooling air exhausted to the exhaust port 55 is prevented from being mixed into the intake port 45 indiscriminately. The direction in which the cooling air is introduced into the intake duct 40 and the direction in which the cooling air is discharged from the exhaust duct 50 are of the same Z type. The cooling air passes between the cells 20 and forms a direct air-cooling structure for cooling the heat generated during the charging and discharging of the cells 20. [

FIG. 2 is a perspective view showing only a cell stack portion in the battery pack of FIG. 1; FIG.

2, a plurality of cells 20 are stacked in a vertical direction with respect to a paper surface at regular intervals, and the cartridges 25 are stacked together with the unidirectional thermally deformable material portion 27, The air flow path 26 is formed so that the cooling air can flow between the air flow paths 20. Here, the unidirectional thermally deformable material portion 27 provides an air flow path 26 between the stacked cells 20, and the air flow path 26 is defined as a space between the unidirectional thermally deformable material portions 27 . In the illustrated example, three air flow passages are formed for each cell with respect to the ground surface. The unidirectional thermally deformable material portion 27 can be molded integrally with the cartridge 25 to support the cells 20 with the cartridge 25 and to form the air flow path 26 between the cells 20. [

The intake port 45 may be formed perpendicular to the flow direction of the cooling air passing through the air flow path 26 formed between the plurality of cells 20 of the cell stack 30. That is, the air inlet port 45 is formed in the air flow passage 26 so as to be perpendicular to the flow direction of the cooling air passing through the air flow passage 26, The length of the intake duct 40 connecting the intake duct 30 may be short and not be bent. This can reduce the flow resistance of the cooling air that is drawn into the inlet port 45 and improve the cooling performance of the battery pack 100 because the cooling air is smoothly introduced into the air flow path 26.

The battery pack 100 according to the present embodiment is a cooling device for cooling the cells 20 including the thermally deformable material portion 27 located between the stacked cells 20, And the exhaust duct 50, but examples of the cooling device are not limited to these, and various configurations are possible.

FIG. 3 shows only two cell portions in a cross section of the cell stack of FIG. 1 that are parallel to the stacking direction of the cell stack. In the case where the unidirectional heat deforming material portion 27 thermally expands along the stacking direction y of the cells Yes.

the unidirectional thermally deformable material portion 27 thermally expands in the y direction to become the unidirectional thermally deformable material portion 27 'as shown in (b), and the air flow path 26' Is increased in height as compared with the air passage 26 of (a). When the abnormal high temperature portion is formed in the cell 20, the amount of the cooling air flowing through the air flow path 26 due to the deformation of the unidirectional thermally deformable material portion 27 can be increased. As described above, the cooling device of the battery pack according to the present invention is variable.

FIG. 4 shows only two cell portions in the cross section of the cell stack in the stacking direction of the cell stack in FIG. 1, in which unidirectional thermally deformable material portions 27 extend along a direction (x) This is an example of the case of heat shrinkage.

the unidirectional thermally deformable material portion 27 is thermally shrunk in the x direction to become the unidirectional thermally deformable material portion 27 "as shown in (b), and the air flow path 26" Is increased in width as compared with the air passage 26 of (a). When the abnormal high temperature portion is formed in the cell 20, the amount of the cooling air flowing through the air flow path 26 due to the deformation of the unidirectional thermally deformable material portion 27 can be increased. As described above, the cooling device of the battery pack according to the present invention is variable.

The thermal deformation is reversible so that it is in an expanded state as in the case of the unidirectional thermally deformable material portion 27 'in Fig. 3 (b) and in the contracted state as in the unidirectional thermally deformable material portion 27' Unidirectional thermally deformable material portion 27 as shown in Figs. 3 (a) and 4 (a).

The unidirectional thermally deformable material portion 27 can be any one of plastics, polymers, oligomers, derivatives thereof, or combinations thereof. In particular, the material that uni-directionally shrinks as in Fig. 4 includes polyester or derivatives thereof.

On the other hand, the cell 20 may have a structure in which a plurality of cells 20 are simply laminated while interposing an insulating film between the cells 20. As another example, the cells 20 may be formed by arranging the cells 20 at appropriate intervals on the upper and / or lower portions of the insulating film and then folding the insulating film together with the cells 20 in one direction to form the cells 20 between the folded insulating films. Lt; RTI ID = 0.0 > stacked < / RTI > folding structure. In this case, the air flow path 26 can be formed by interposing the unidirectional thermally deformable material portion 27 between the cells 20, separately from the cartridge 25.

FIG. 5 is a perspective view of a battery pack according to another embodiment of the present invention, and FIG. 6 is a front view.

5 and 6, a battery pack 200 includes a heat sink 150 disposed on one side of a cell stack 130 in which a plurality of cells 120 are stacked, And the heat sink 150 is provided with a flow passage 160 for cooling water.

The cell 120 is preferably a plate-shaped cell so as to provide a high laminating ratio in a limited space, and may be formed by stacking the cell 120 so as to face one or both of the adjacent cells 120 to form the cell stack 130 .

The heat sink 150 refers to an object that absorbs heat and emits heat from other objects by thermal contact. The heat sink 150 is a hollow structure including a flow passage 160 therein. The coolant flowing in the internal flow path 160 of the heat sink 150 is not particularly limited as long as the coolant flows easily in the flow path 160 and is excellent in cooling ability, and may be a gas or a liquid. For example, the latent heat is high and can be water that can maximize cooling efficiency. However, the present invention is not limited to this, and it may be an antifreeze, gas refrigerant, air or the like as long as a flow occurs.

The heat sink 150 further includes a cooling fin 127 that absorbs heat conducted from the cooling fins 127. The cooling fins 127 are disposed on the cooling fins 127, 127).

The cooling fin 127 is interposed between the cells 120 in such a manner that both surfaces of the cooling fin 127 are in close contact with the cells 120 and is bent into a shape in surface contact with the heat sink 150. That is, when the cooling fin 127 is interposed between the cells 120, since the cooling fin 127 is in surface contact with the heat sink 150, the heat radiation effect due to heat conduction can be maximized. The illustrated cooling fins 127 may be "T" -shaped in vertical section, but may be "-shaped" depending on the bending direction.

The cooling fin 127 is made of the unidirectional heat-deformable material portion 27 as described with reference to Fig. It is preferable to increase the cross-sectional area of the heat discharge path by conduction by thermally expanding along the stacking direction (y) of the cells 120 when the temperature of the cells 120 rises. When the cell temperature rises in a normal state, if the cooling fin 127 thermally expands in the y direction to increase the endothermic volume, the heat can be transferred more quickly and the cooling can be performed. As described above, the cooling device of the battery pack according to the present invention is variable.

As described above, the battery pack 200 according to the present embodiment includes a cooling fin 127 formed of a heat deformable material portion positioned between the stacked cells 120 to cool the cells 120, (150), but examples of the cooling device are not limited to these, and various configurations are possible.

The battery pack may be manufactured by assembling a battery module as a unit module according to a desired output and capacity. In consideration of mounting efficiency and structural stability, an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, The present invention can be suitably used as a power source for devices, but is not limited thereto.

Therefore, the present invention can be used for providing a device including the battery pack as a power source, and the device can be specifically an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle or a power storage device. The structure and manufacturing method of such a device are well known in the art, so a detailed description thereof will be omitted herein.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but many variations and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims. It will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the appended claims.

20, 120 ... cell 25 ... cartridge
30, 130 ... cell stack body 40 ... intake duct
50 ... exhaust duct 45 ... intake port
55 ... exhaust 100, 200 .. Battery pack
127 ... Cooling pin 150 ... Heatsink

Claims (6)

A cell stacked structure in which a plurality of cells are fixed to a cartridge, respectively; And
Comprising an intake duct and an exhaust duct,
Wherein the unidirectional thermal deformation material portion is formed integrally with the cartridge so that the cartridge supports the cells with the cartridge and an air flow path defined between the cells is defined as a space between the unidirectional thermal deformation material portions,
Wherein the unidirectional thermally deformable material portion thermally expands along the stacking direction of the cells when the temperatures of the cells rise to increase the height of the air flow path,
Wherein one end of the intake duct is connected to an intake port through which the cooling air is introduced and the other end is open to the side of the cell stack body and one end is connected to an exhaust port through which the cooling air having passed through the air flow path is discharged, And the air intake port is formed perpendicular to the flow direction of the cooling air passing through the air flow path. The air intake duct according to any one of claims 1 to 3, Battery pack. A cell stacked structure in which a plurality of cells are fixed to a cartridge, respectively; And
Comprising an intake duct and an exhaust duct,
Wherein the unidirectional thermal deformation material portion is formed integrally with the cartridge so that the cartridge supports the cells with the cartridge and an air flow path defined between the cells is defined as a space between the unidirectional thermal deformation material portions,
Wherein the unidirectional thermally deformable material portion is heat shrunk in a direction perpendicular to the stacking direction of the cells when the temperatures of the cells rise, thereby increasing a width of the air flow path,
Wherein one end of the intake duct is connected to an intake port through which the cooling air is introduced and the other end is open to the side of the cell stack body and one end is connected to an exhaust port through which the cooling air having passed through the air flow path is discharged, And the air intake port is formed perpendicular to the flow direction of the cooling air passing through the air flow path. The air intake duct according to any one of claims 1 to 3, Battery pack. 3. The method according to claim 1 or 2,
Wherein the unidirectional thermally deformable material portion is any one of plastics, polymers, oligomers, derivatives thereof, or combinations thereof. A cell stacked structure in which a plurality of cells are fixed to a cartridge, respectively; And
A battery pack including an intake duct and an exhaust duct is manufactured,
Wherein the unidirectional thermal deformation material portion is formed integrally with the cartridge so that the cartridge supports the cells with the cartridge and an air flow path defined between the cells is defined as a space between the unidirectional thermal deformation material portions,
Wherein the unidirectional thermally deformable material portion thermally expands along the stacking direction of the cells when the temperatures of the cells rise to increase the height of the air flow path,
Wherein one end of the intake duct is connected to an intake port through which the cooling air is introduced and the other end is open to the side of the cell stack body and one end is connected to an exhaust port through which the cooling air having passed through the air flow path is discharged, And the air intake port is formed perpendicular to the flow direction of the cooling air passing through the air flow path. The air intake duct according to any one of claims 1 to 3, A method of manufacturing a battery pack. A cell stacked structure in which a plurality of cells are fixed to a cartridge, respectively; And
A battery pack including an intake duct and an exhaust duct is manufactured,
Wherein the unidirectional thermal deformation material portion is formed integrally with the cartridge so that the cartridge supports the cells with the cartridge and an air flow path defined between the cells is defined as a space between the unidirectional thermal deformation material portions,
Wherein the unidirectional thermally deformable material portion is heat shrunk in a direction perpendicular to the stacking direction of the cells when the temperatures of the cells rise, thereby increasing a width of the air flow path,
Wherein one end of the intake duct is connected to an intake port through which the cooling air is introduced and the other end is open to the side of the cell stack body and one end is connected to an exhaust port through which the cooling air having passed through the air flow path is discharged, And the air intake port is formed perpendicular to the flow direction of the cooling air passing through the air flow path. The air intake duct according to any one of claims 1 to 3, A method of manufacturing a battery pack. The method according to claim 4 or 5,
Wherein the unidirectional thermally deformable material portion is any one of plastic, polymer, oligomer, derivatives thereof, or a combination thereof.

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