JP5055198B2 - Battery module - Google Patents

Description

  The present invention relates to a battery module, and more particularly, to a battery module in which a rectangular sealed secondary battery having a laminate film as a battery container is fixed to a metal heat sink.

  For example, a battery module used in a hybrid vehicle, an electric vehicle (hereinafter, referred to as an electric vehicle) or the like requires a high voltage, and thus a large number of cylindrical sealed single cells (so-called “cells”) (for example, , 40 to 100) are connected in series, and a plurality of battery modules are used in series and parallel as necessary. Such a cell generally has a structure suitable for large current discharge, and has a larger capacity (eg, 3 Ah or more) than a small consumer battery. In addition, a battery module used in an electric vehicle is strongly required to have a compact design from the viewpoint of effectively using a space in the vehicle.

  Conventionally, a cylindrical sealed battery employs a sealed structure in which a battery can and a battery lid are caulked in a state where a wound electrode group is infiltrated with an electrolyte in a bottomed cylindrical battery can. For this battery can, it is common to use an iron-based material for cost reduction. However, since iron has a large specific gravity, it has been a major limitation in increasing the weight efficiency of the unit cell.

  In order to solve this problem, a so-called laminate cell using a laminate film in which an aluminum foil or the like is incorporated as an inner layer as a gas barrier layer as a battery container has been known for a long time (see, for example, Patent Document 1). The laminate cell has a structure in which an electrode group in which positive and negative electrodes cut into strips are alternately laminated, or an electrode group wound in a flat shape is housed in a container made of a laminate film. The outer shape is generally rectangular (cuboid) or plate-like. A battery module using a laminate cell is also disclosed (see, for example, Patent Document 2).

JP-A-60-230354 JP 2006-252855 A

  When a battery module is configured by using a plurality of rectangular laminate cells, the area where the surface of the laminate cell is in contact with the cooling air is smaller than that of the above-described cylindrical unit cell, and thus improvement in heat dissipation becomes a problem. In other words, if the temperature of each laminate cell varies, the amount of charge between the laminate cells will vary, and some laminate cells will be a load on other laminate cells, or the life of the entire battery module will be shortened. Problems arise.

  On the other hand, when the battery module is mounted on an electric vehicle, it is important to ensure durability (vibration resistance) against vibration during traveling. However, such a rectangular laminate cell is difficult to remove the air layer formed between the laminate cell and the heat sink by simply overlapping (stacking) with the heat sink by pressing. It is difficult to ensure vibration resistance because the conductivity tends to deteriorate and the laminate film has a small coefficient of friction and is easy to slide.

  For this reason, in the battery module using a laminate cell, it is desirable to make it the structure which bonded each laminate cell or the laminate cell, and the heat sink with the adhesive material. However, in general, adhesive materials having excellent thermal conductivity have low adhesive strength, and those having excellent adhesive strength have low thermal conductivity, making it difficult to achieve both heat dissipation and vibration resistance.

  An object of the present invention is to provide a battery module excellent in heat dissipation and vibration resistance in view of the above-mentioned cases.

  In order to solve the above problems, the present invention provides a battery module in which a rectangular sealed secondary battery having a laminate film as a battery container is fixed to a metal heat sink, and at least one surface side of the secondary battery is The heat radiation plate is bonded together using a first adhesive material having a thermal conductivity of 0.8 W / mK or more and a second adhesive material having an adhesive strength of 3 N / 10 mm width or more in combination. To do.

  The heat generated in the laminate cell occurs almost evenly inside the electrode group in which the positive and negative electrodes are arranged with the separator interposed therebetween. However, since the center part is particularly difficult to dissipate heat, the heat tends to accumulate and the temperature tends to rise. Therefore, in order to dissipate heat from the laminate cell, it is particularly effective to dissipate heat at the center. On the other hand, in order to improve vibration resistance, it is effective to firmly hold the outer peripheral portion of the rectangular laminate cell. Therefore, in the battery module of the present invention, the first adhesive material having excellent heat dissipation and thermal conductivity of 0.8 W / mK or more at the central portion of the laminate cell among the bonding surfaces of the laminate cell and the heat sink. Is used, and the outer peripheral portion of the laminate cell is bonded to the heat radiating plate using a second adhesive material having excellent adhesive strength and an adhesive strength of 3 N / 10 mm width or more. By adopting such a configuration, the heat generated inside the laminate cell is efficiently transmitted to the heat dissipation plate via the first adhesive material, and the laminate cell efficiently handles the vibration by the second adhesive material. Since it is held by the heat radiating plate, it is possible to obtain a battery module that is excellent in both heat dissipation and vibration resistance.

  In the present invention, it is preferable that a plurality of gaps are formed between the second adhesive materials, and it is more preferable that a gap is formed between the first and second adhesive materials. Further, the first adhesive material preferably has an area of 30% or more of the area of the bonding surface, and the second adhesive material preferably has an area of 30% or more of the area of the bonding surface. . Furthermore, the thickness of the first and second adhesive materials is more preferably 0.15 mm or less, and the thickness of the first and second adhesive materials is more preferably the same. Also, for example, since the operation of applying the adhesive material to a thickness of 0.15 mm or less is difficult to manage, use a double-sided adhesive tape in which the adhesive material is processed into a sheet with a certain thickness and bonded to a release paper in advance. You may do it.

  According to the present invention, at least one surface side of the secondary battery is a heat sink, the first adhesive material having a thermal conductivity of 0.8 W / mK or more, and the second adhesive material having an adhesive strength of 3 N / 10 mm width or more. Since it is bonded together, it is efficiently transmitted to the heat radiating plate through the first adhesive material, and the laminate cell is efficiently held on the heat radiating plate by the second adhesive material against vibration. Therefore, the effect that a battery module excellent in heat dissipation and vibration resistance can be obtained can be obtained.

  Hereinafter, embodiments of a battery module to which the present invention can be applied will be described with reference to the drawings.

1. Laminate cell (preparation of positive electrode)
Lithium transition metal double oxide as a positive electrode active material, carbon powder as a conductive material, and polyvinylidene fluoride (PVDF) as a binder are dispersed and mixed in a solvent N-methyl-2-pyrrolidone (NMP). To make a slurry. This slurry is applied to both surfaces of an aluminum alloy foil having a thickness of 20 μm to be a core material (current collector), dried, and then pressed to be integrated. Thereafter, the coated portion was cut to a width of 86 mm, and the plain portion (see reference numeral 7 in FIG. 1) was cut to a width of 17 mm to produce a hoop-shaped positive electrode.

(Preparation of negative electrode)
Carbon particles as a negative electrode active material and PVDF as a binder are added to NMP as a solvent and mixed to prepare a slurry solution. This slurry is applied to both surfaces of a copper foil having a thickness of 10 μm to be a core material (current collector), dried, and then pressed to be integrated. Thereafter, the coated part was cut to a width of 88 mm, and the plain part (see reference numeral 9 in FIG. 1) was cut to a width of 15 mm to produce a hoop-shaped negative electrode.

(Production of laminate cell)
The produced positive electrode was sealed in a bag shape by thermal welding in a separator made of a polyethylene porous film having a thickness of 25 μm. As shown in FIG. 1, the positive electrode strap 6 from which the positive electrode terminal 2 is led out, the positive electrode uncoated portion 7, and the negative electrode strap 8 from which the negative electrode terminal 3 is led out are stacked. And the negative electrode plain portion 9 were ultrasonically welded to form an electrode group 4.

  The positive electrode strap 6 is made of an aluminum alloy having a thickness of 0.3 mm (JIS A3003 equivalent), and only the portion of the positive electrode terminal 2 that is not in contact with the electrolyte (exposed portion outside the battery) has a thickness of 0 on one side. .1 mm of nickel was clad. On the other hand, a 0.3 mm thick copper plate (JIS C1020 equivalent) was used for the negative electrode strap 8, and nickel having a thickness of 0.05 mm was clad on both sides of only the portion of the negative electrode terminal 3 exposed outside the battery. The electrode group 4 has a thickness of about 4.8 mm and a capacity of about 3.2 Ah.

  The electrode group 4 is placed on a laminate film 1 made of PP-aluminum foil-PET molded into a cup shape and having a thickness of about 120 μm, and a planar laminate film 1 ′ made of the same material is placed and sealed by thermal welding. did. At this time, after injecting a predetermined amount of electrolyte using a syringe from the mating surfaces that were left without being partly welded, this part was again heat-sealed in vacuum and sealed to produce a laminate cell 12. . The width | variety of the heat welding part 10 was about 10 mm over the perimeter. In addition, the sealing material 11 was interposed in the location where the positive electrode terminal 2 and the negative electrode terminal 3 of the heat welding part 10 were arrange | positioned, in order to prevent the liquid leakage of electrolyte solution.

2. Battery Module As shown in FIG. 2, a battery module 30 of 2 parallel 4 series was assembled using 8 laminate cells 12 obtained as described above. The battery module 30 includes eight laminate cells 12, heat radiation plates 15, 16 and 17, connectors 18 for connection, laminate cells 12, and adhesive materials for fixing the laminate cells 12 to the heat radiation plates 15 to 17, and heat radiation plates. It comprises a tapping screw 19 for fixing and integrating 15 to 17. The capacity of the battery module 30 is about 6.4 Ah because the two laminated cells 12 are connected in parallel.

  Two laminate cells 12 are fixed to one surface of the heat sinks 16 and 17 serving as side edges of the battery module 30 by an adhesive material, and two ( A total of 4) laminate cells 12 are fixed by an adhesive. An aluminum alloy having a thickness of 0.5 mm (JIS A5052 equivalent) is used for the heat sinks 15 to 17, and the bonding surface 5 (see FIG. 1) of each laminate cell 12 and each heat sink 15 to 17 is used. The dimensions were 105 mm x 85 mm.

  Each laminate cell 12 and each of the heat sinks 15 to 17 are bonded together using two types of adhesive materials (first and second adhesive materials described later). Examples of such bonding modes include the modes shown in FIGS. 3 and 4, but the present invention is not limited to this.

  In the aspect shown in FIG. 3, in the portion corresponding to 30% or more as the area ratio of the central portion (including the center) of the bonding surface 5 with the radiator plates 15 to 17 of the laminate cell 12 to the bonding surface 5, The first adhesive material 14 having a thermal conductivity of 0.8 W / mK or more when solidified is applied with a thickness of 0.15 mm or less, and the area ratio of the outer peripheral portion to the bonding surface 5 is 30. % Of the second pressure-sensitive adhesive material 13 having a peeling strength (adhesive strength) of 3 N / 10 mm or more when solidified is the same thickness as the first pressure-sensitive adhesive material 14 (0.15 mm). The following are applied in four straight lines. Further, in order to further improve heat dissipation by forming an air flow path, a gap 20 is formed between the first adhesive material 14 and each second adhesive material 13, and the second adhesive material 13. A gap 21 is also formed therebetween. The gap here means a portion where the adhesive material is not applied.

  On the other hand, in the embodiment shown in FIG. 4, the first adhesive material 14 and the second adhesive material 13 are applied in stripes on the bonding surface 5 of the laminate cell 12 with the heat dissipation plates 15 to 17, and the heat dissipation plate 15. It is an example fixed to ˜17. Similarly to the embodiment shown in FIG. 3, when solidified to a portion corresponding to 30% or more of the area ratio of the central portion (including the center) of the bonding surface 5 to the bonding surface 5, 0.8 W / mK. The first pressure-sensitive adhesive material 14 having the above thermal conductivity is applied with a thickness of 0.15 mm or less, and a portion corresponding to 30% or more as an area ratio of the outer peripheral portion (both sides) to the bonding surface 5 In addition, the second adhesive material 13 that provides a peel strength (adhesive strength) of 3 N / 10 mm width or more when solidified is applied at two locations with the same thickness (0.15 mm or less) as the first adhesive material 14. Has been. Also in this embodiment, a gap 20 is formed between the first adhesive material 14 and each of the second adhesive materials 13 in order to form an air flow path and further improve heat dissipation.

  In order to secure the fixation (vibration resistance) of the laminate cell 12, on the surface opposite to the bonding surface 5 of the laminate cell 12 with the heat radiation plates 15 to 17, that is, the bonding surface 5 ′ of the laminate cells 12 to each other. Is coated with the second adhesive material 13 having excellent adhesive strength.

  As shown in FIG. 2, the heat sink 15 disposed in the center and the heat sink 17 disposed on one side have different lengths (0.5 mm × 2) in the longitudinal direction (the heat sink 15 Except for the (short) point, it is the same shape, and the both ends constitute an arm part bent in a right angle direction. A total of four screw holes are formed at the end of the arm part, two at the top and the bottom, and the center of the arm part is cut out. On the other hand, the heat radiating plate 16 disposed on the other side has a longer arm portion than the heat radiating plates 15 and 17 and a length (0.5 mm × 2) longer than the heat radiating plate 17 in the longitudinal direction. Except for a long point, the shape is the same as the heat sinks 15 and 17. Accordingly, the four screw holes formed in the end portions of the arm portions of the heat radiating plates 15 to 17 are formed so as to be located at the same position when the heat radiating plates 15 to 17 are overlapped (assembled).

  The heat radiating plates 15 to 17 are fixed by four tapping screws 19 (a part of tapping screws are omitted in FIG. 2), and a connector 18 (a part of the connectors is omitted in FIG. 2) through a notch portion of the arm portion. ), And the two parallel 4 series battery modules 30 are assembled as described above.

  Next, the battery module of the Example produced according to the said embodiment is demonstrated. In addition, it describes together about the battery module of the comparative example produced for the comparison.

Example 1
As shown in FIG. 3, when solidified into a portion corresponding to 30% of the area ratio of the central portion of the bonding surface 5 with the radiator plates 15 to 17 of the laminate cell 12 to the bonding surface 5, 0.8 W When the first adhesive material 14 having a thermal conductivity of / mK is applied with a thickness of 0.15 mm and solidified into a portion corresponding to 30% as an area ratio of the outer peripheral portion to the bonding surface 5 The 2nd adhesive material 13 from which the peeling strength of 3N / 10mm width was obtained was apply | coated to four places linearly with the same thickness (0.15mm) as the 1st adhesive material 14. FIG. Further, a gap 20 was formed between the first adhesive material 14 and each second adhesive material 13, and a gap 21 was also formed between the second adhesive materials 13.

(Example 2)
As shown in FIG. 4, when solidified into a portion corresponding to 30% of the area ratio with respect to the bonding surface 5 of the central surface of the bonding surface 5 with the radiator plates 15 to 17 of the laminate cell 12, 0.8 W First adhesive material 14 having a thermal conductivity of / mK is applied with a thickness of 0.15 mm, and solidified into a portion corresponding to 30% of the outer peripheral portion (both sides) as an area ratio with respect to the bonding surface 5 Then, the second pressure-sensitive adhesive material 13 having a 3N / 10 mm width peel strength was applied at two locations with the same thickness (0.15 mm) as the first pressure-sensitive adhesive material 14. A gap 20 was formed between the first adhesive material 14 and each second adhesive material 13.

(Example 3)
In Example 3, the application position, application area, and application thickness of the adhesive material are the same as in Example 1, but the first adhesive material 14 having a thermal conductivity of 1 W / mK when solidified and the width of 3 N / 10 mm The second pressure-sensitive adhesive material 13 capable of obtaining the peel strength of was used.

Example 4
In Example 4, the application position, application area, and application thickness of the adhesive material are the same as in Example 1, but the first adhesive materials 14 and 3 having a thermal conductivity of 0.8 W / mK when solidified. The second pressure-sensitive adhesive material 13 that can provide a peel strength of 8 N / 10 mm width was used.

(Example 5)
In Example 5, although the kind, application position, and application area of the adhesive material were the same as in Example 1, the thickness of the first adhesive material 14 and the second adhesive material 13 was 0.2 mm.

(Example 6)
In Example 6, the adhesive material is not applied in the assembly process of the battery module 30, but a so-called double-sided adhesive tape that has been processed into a 0.1 mm sheet shape and bonded to the release paper in advance is used. The sticking position and area of each pressure-sensitive adhesive tape are the same as in Example 1, and the pressure-sensitive adhesive material used is also the same as in Example 1. The first pressure-sensitive adhesive having a thermal conductivity of 0.8 W / mK when solidified. The material and the 2nd adhesive material from which the peeling strength of 3N / 10mm width was obtained were used.

(Comparative Example 1)
In Comparative Example 1, as in the conventional case, the second adhesive 13 that provides a peel strength of 3 N / 10 mm width when solidified on the entire surface of the bonding surface 5 of the laminate cell 12 with the heat dissipation plates 15 to 17. Only (application thickness 0.15 mm) was used.

(Comparative Example 2)
In Comparative Example 2, the first adhesive material 14 having a thermal conductivity of 0.8 W / mK when applied to the entire surface of the bonding surface 5 of the laminate cell 12 to the heat radiation plates 15 to 17 (with a coating thickness of 0.1 mm). Only 15 mm). In addition, the 2nd adhesive material 13 was used for bonding surface 5 'of the lamination cells 12 similarly to embodiment.

(Comparative Example 3)
In Comparative Example 3, the application position, application area, and application thickness of the adhesive material are the same as in Example 1, but the first adhesive material having a thermal conductivity of 0.65 W / mK when solidified and 3 N / 10 mm. The second pressure-sensitive adhesive material 13 capable of obtaining the peel strength of the width was used.

(Comparative Example 4)
In Comparative Example 4, the application position, the application area, and the application thickness of the adhesive material are the same as in Example 1, but the first adhesive materials 14 and 2 having a thermal conductivity of 0.8 W / mK when solidified. A second pressure-sensitive adhesive material capable of obtaining a 4N / 10 mm width peel strength was used.

(test)
About the battery module of the produced said Example and comparative example, the vibration resistance and the heat dissipation test were done. The contents of the test are as follows.

<Vibration resistance test>
When the battery module is vibrated in the vertical direction at an acceleration of 5 G for 100 hours continuously, if the movement of the bonding surface 5 is 0.5 mm or less in the vertical direction, ○, if it exceeds 0.5 mm and 1 mm or less, Δ, When it moved beyond 1 mm or the battery module was damaged, it was determined as x.

<Heat dissipation test>
When the battery module is repeatedly charged and discharged 80 times from 100% SOC to 5% SOC at 1 C current (6.4 A for 2 parallels) in an atmosphere of 25 ° C. When the maximum temperature in the central portion was 45 ° C. or less, it was judged as “◯”, when it exceeded 45 ° C. and 50 ° C. or less, Δ, and when it exceeded 50 ° C., it was judged as ×.

  Table 1 below shows the test results of the vibration resistance test and the heat dissipation test.

  As is clear from Table 1, the battery module of Comparative Example 1 is excellent in vibration resistance but has insufficient heat dissipation. The battery module of Comparative Example 2 has the opposite result from that of Comparative Example 1. The battery module of Example 5 having a thick application thickness of the adhesive material of 0.2 mm did not provide sufficient heat dissipation. Even an adhesive material excellent in thermal conductivity is desired to have a thickness of 0.15 mm or less because heat dissipation is insufficient when the coating thickness is large. The battery modules of Examples 1 to 4 and 6 are excellent in both vibration resistance and heat dissipation. However, in consideration of cost, it is not necessary to use an adhesive material having a higher thermal conductivity or an adhesive material having a higher adhesive strength than necessary. In practical use, the battery modules of Examples 1, 2, and 6 are sufficient. In particular, since the battery module of Example 6 uses a double-sided pressure-sensitive adhesive tape, it is easy to manage work and is a preferred mode.

(Action / Effect)
Next, functions and effects of the battery module 30 of the present embodiment will be described.

  In the battery module 30 of the present embodiment, among the bonded surfaces of each laminate cell 12 and the heat sinks 15 to 17, the heat conductivity is 0.8 W / mK or more at the center portion of the laminate cell 12 with excellent heat dissipation. The first adhesive material 14 is used, and the outer peripheral portion of the laminate cell 12 is bonded to the heat radiating plate using the second adhesive material 13 having excellent adhesive strength and having an adhesive strength of 3 N / 10 mm width or more. For this reason, the heat generated inside the laminate cell 12 is efficiently transmitted to the heat dissipation plates 15 to 17 through the first adhesive material 14, and the laminate cell 12 is efficient by the second adhesive material 13 against vibration. Therefore, it is held by the heat sinks 15-17. That is, the heat generation of the laminate cell 12 occurs almost evenly inside the electrode group 4, but the center portion is particularly difficult to dissipate heat, so the heat is trapped and the temperature rises easily. While it is effective to consider the heat radiation of the part, it is effective to firmly hold the outer peripheral part of the rectangular laminate cell 12 in order to improve the vibration resistance. Further, a gap 20 is formed between the first adhesive material 14 and each second adhesive material 13 (an embodiment shown in FIGS. 3 and 4), and a gap 21 is also formed between the second adhesive materials 13. It is formed (mode shown in FIG. 3). For this reason, the air flow path can be formed to further enhance the heat dissipation. Therefore, the battery module 30 of this embodiment is excellent in both heat dissipation and vibration resistance as shown in the test results.

  Further, in the battery module 30 of the present embodiment, the eight laminated cells 12 are arranged in a compact manner via the heat dissipation plate, so that the entire module can be reduced in size. Further, since the heat sinks 16 and 17 made of aluminum alloy serve as an outer case, the weight can be reduced.

  In the present embodiment, the stacked electrode group 4 is exemplified, but the present invention is not limited to this, and a flat wound electrode group may be used. Moreover, in this embodiment, although the example which fixed the laminate cell 12 to the heat sinks 15-17 two by two was shown, this invention is not limited to this, For example, three or more laminate cells 12 are heat-radiated at a time. You may make it fix to the plates 15-17 with an adhesive material. That is, the present invention is not limited to the series-parallel state of the laminate cells 12 and can be applied. Furthermore, in the present embodiment, the structure in which one surface side of the laminate cell is fixed to the heat radiating plate is illustrated, but the present invention is not limited thereto, and for example, a structure in which both surface sides are fixed to the heat radiating plate may be adopted. Good.

  Since the present invention provides a battery module with excellent heat dissipation and vibration resistance, it contributes to the manufacture or sale of battery modules, and thus has industrial applicability.

It is the top view and side sectional view which show the laminate cell used for the battery module of embodiment which can apply this invention. It is a disassembled perspective view of the battery module of an embodiment. It is a top view which shows typically the one aspect | mode of the position of the 1st adhesive material and the 2nd adhesive material which were apply | coated to the bonding surface of the laminate cell used for the battery module of embodiment. It is a top view which shows typically the other aspect of the position of the 1st adhesive material and the 2nd adhesive material which were apply | coated to the bonding surface of the laminate cell used for the battery module of embodiment.

Explanation of symbols

1 Laminate film 1 'Laminate film 12 Laminate cell (sealed secondary battery)
13 2nd adhesive material 14 1st adhesive materials 15, 16, and 17 Heat sink 20, 21 Crevice 30 Battery module

Claims (8)

  A battery module in which a rectangular sealed secondary battery having a laminate film as a battery container is fixed to a metal heat sink, wherein at least one side of the secondary battery is the heat sink and the thermal conductivity is 0.8 W. A battery module comprising: a first adhesive material having an adhesive strength of not less than / mK and a second adhesive material having an adhesive strength of not less than 3 N / 10 mm.   The first adhesive material is disposed at the center of the bonding surface between the secondary battery and the heat sink, and the second adhesive material is disposed at the outer periphery of the bonding surface. The battery module according to claim 1.   The battery module according to claim 2, wherein a plurality of gaps are formed between the second adhesive materials.   The battery module according to claim 2, wherein a gap is formed between the first and second adhesive materials.   The first pressure-sensitive adhesive material has an area of 30% or more of the area of the bonding surface, and the second pressure-sensitive adhesive material has an area of 30% or more of the area of the bonding surface. The battery module according to any one of claims 2 to 4, wherein:   6. The battery module according to claim 1, wherein a thickness of each of the first and second adhesive materials is 0.15 mm or less.   The battery module according to claim 6, wherein the first and second adhesive materials have the same thickness.   The battery module according to any one of claims 1 to 7, wherein a double-sided adhesive tape is used for the first and second adhesive materials.

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