Manufacturing method for energy storage devices

Abstract

To suppress the increase in thermal resistance caused by a thermally conductive adhesive in a structure where a thermally conductive adhesive is interposed between a battery and a cooler. [Solution] A method for manufacturing an energy storage device comprising a battery and a cooler, comprising: a coating step of applying a thermally conductive adhesive to an object to be coated; a temperature control step of raising the temperature of the battery; and an bonding step of bonding the battery and the object to be coated by sandwiching the adhesive between the heated battery and the object to be coated, wherein in the bonding step, the battery and the object to be coated are thermally connected via the adhesive.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a power storage device.

Background Art

[0002] Patent Document 1 discloses a power storage device in which an insulating layer is interposed between a battery cell and a heat sink, and an adhesive layer having thermal conductivity is interposed between the insulating layer and the battery cell.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the configuration described in Patent Document 1, the adhesive constituting the adhesive layer has high thermal dependence. Therefore, when manufacturing the power storage device, if the adhesive is in a low-temperature state, the viscosity of the adhesive increases, and it becomes difficult for the adhesive to be crushed between the battery cell and the insulating layer. If the required crushed state of the adhesive cannot be achieved during manufacturing, the adhesive layer becomes thick, and the thermal resistance of the adhesive layer becomes larger than expected, resulting in a decrease in cooling performance.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for manufacturing a power storage device capable of suppressing an increase in thermal resistance due to an adhesive in a structure in which an adhesive having thermal conductivity is interposed between a battery and a cooler.

Means for Solving the Problems

[0006] The present invention relates to a method for manufacturing an energy storage device comprising a battery and a cooler, comprising: a coating step of applying a thermally conductive adhesive to an object to be coated; a temperature control step of raising the temperature of the battery; and an bonding step of bonding the battery and the object to be coated by sandwiching the adhesive between the battery, whose temperature has been raised and the object to be coated, wherein in the bonding step, the battery and the cooler are thermally connected via the adhesive by bonding the battery and the object to be coated with the adhesive. [Effects of the Invention]

[0007] In this invention, it is possible to suppress the increase in thermal resistance due to the adhesive in a structure in which a battery and a cooler are thermally connected via an adhesive. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram showing an energy storage device in an embodiment. [Figure 2] This is a cross-sectional view showing the structure of an energy storage device. [Figure 3] This is a cross-sectional view showing the adhesive layer formed by the adhesive. [Figure 4] This is a flowchart illustrating the manufacturing method of an energy storage device. [Figure 5] This is a diagram illustrating the coating process. [Figure 6] This is a diagram illustrating the bonding process. [Figure 7] This is a diagram illustrating the state in which the adhesive has been sufficiently compressed. [Figure 8] This diagram shows the case where the adhesive has not been sufficiently compressed. [Modes for carrying out the invention]

[0009] The method for manufacturing an energy storage device according to embodiments of the present invention will be described in detail below. However, the present invention is not limited to the embodiments described below.

[0010] Figure 1 is a schematic diagram showing an energy storage device in an embodiment. The energy storage device 1 is a battery pack in which multiple battery modules 3 are housed inside a case 2. The energy storage device 1 is installed in electric vehicles such as electric cars and hybrid vehicles. In electric vehicles, the power stored in the energy storage device 1 is supplied to the motor for driving, thereby enabling the vehicle to move.

[0011] The battery module 3 is a battery pack having multiple battery cells 4. Each battery cell 4 is a rechargeable battery housed in a rectangular case. For example, each battery cell 4 is composed of lithium-ion batteries. In the battery module 3, the multiple battery cells 4 are constrained by restraining members.

[0012] As shown in Figure 2, the battery cell 4 is installed at the bottom of the lower case 5. The case 2 has an upper case and a lower case 5. The lower case 5 is integrated with the upper case by bolt fastening or the like.

[0013] The lower case 5 is comprised of a cooler 6. The energy storage device 1 comprises a battery module 3 and a cooler 6. The cooler 6 is a hollow cooler that cools the battery cells 4. The cooler 6 has a flow path through which a cooling liquid circulates.

[0014] The cooler 6 is integrally formed with the lower case 5. The bottom of the lower case 5 is formed by the cooler 6. Since the bottom of the lower case 5 is formed by the cooler 6, the battery cell 4 and the cooler 6 are bonded together by adhesive 7. In other words, the battery cell 4 is bonded to the bottom of the lower case 5 via adhesive 7. The battery cell 4 is the object to be bonded by adhesive 7.

[0015] Adhesive 7 is a thermally conductive adhesive; in other words, adhesive 7 is a thermal conductor. For example, adhesive 7 is a urethane-based adhesive containing a filler. Urethane-based adhesives are more heat-dependent than silicone-based adhesives. Therefore, adhesive 7 is susceptible to temperature changes during the manufacturing of the energy storage device 1.

[0016] As shown in FIGS. 2 and 3, the adhesive 7 is sandwiched between the battery cell 4 and the cooler 6 and cured to form an adhesive layer. The adhesive layer formed by the adhesive 7 is interposed between the battery cell 4 and the cooler 6. In the power storage device 1, the battery cell 4 and the cooler 6 are thermally connected via the adhesive 7.

[0017] In the heat path connecting the battery cell 4 and the cooler 6, the adhesive layer formed by the adhesive 7 is the thermal resistance. Therefore, the thinner the adhesive 7, the larger the contact area between the adhesive 7 and the battery cell 4, and the larger the contact area between the adhesive 7 and the cooler 6, the easier it is to transfer heat in the heat path. On the other hand, the thicker the adhesive 7, the smaller the contact area between the adhesive 7 and the battery cell 4, and the smaller the contact area between the adhesive 7 and the cooler 6, the more difficult it is to transfer heat in the heat path.

[0018] In the power storage device 1 configured as described above, since the thermal resistance of the adhesive 7 is as expected, the cooling performance when the cooler 6 cools the battery cell 4 can achieve the target. If the thermal resistance of the adhesive 7 becomes larger than expected, the target cooling performance cannot be achieved as an electric vehicle. In other words, in order to achieve the target cooling performance for the battery cell 4, it is essential that the adhesive 7 is crushed as expected during the manufacture of the power storage device 1. Therefore, in the manufacturing method of the power storage device 1, when crushing the adhesive 7 with the contacting object, the temperature of the contacting object is controlled in order to crush the adhesive 7 as expected. Thereby, the performance of crushing the adhesive 7 can be improved.

[0019] FIG. 4 is a flowchart showing a manufacturing method of a power storage device. The manufacturing method of the power storage device 1 includes a temperature rising step (step S1), a coating step (step S2), and an adhesion step (step S3).

[0020] The temperature rising step is a step of raising the temperature of the parts (contacting objects) contacting the adhesive 7. The contacting objects include the battery cell 4, the lower case 5, and the cooler 6. Since the cooler 6 and the lower case 5 are integrally formed, the lower case 5 is included in the contacting objects.

[0021] For example, in the heating process, the temperature of the battery cell 4 is increased. In this case, the battery cell 4 is charged and discharged, and the heat generated by the internal resistance associated with charging and discharging is used to raise the temperature of the battery cell 4. At that time, the temperature of the battery cell 4 is measured and it is possible to control it to a temperature at which the adhesive 7 can be crushed. Specifically, the internal resistance of the battery cell 4 is measured, the current at that time is integrated, and the temperature of the battery cell 4 is controlled to reach the target temperature.

[0022] The coating process involves applying adhesive 7 to the object to be coated. The coating process applies a fixed amount of adhesive 7 to the desired location on the object to be coated. In the coating process, as shown in Figure 5, adhesive 7 is applied to the case 2. At that time, adhesive 7 is applied to the part of the case 2 where the battery module 3 is installed. More specifically, adhesive 7 is applied to the part of the lower case 5 where the battery cell 4 is installed. If the bottom of the lower case 5 is composed of a cooler 6, adhesive 7 is applied to the upper surface of the cooler 6 in the coating process. The coating process uses a coating device to apply the adhesive 7. The type of coating device is not particularly limited.

[0023] The bonding process involves bonding the battery cell 4, which has been heated, to the object to be coated by sandwiching the adhesive 7 between the object and the battery cell 4, which has been heated, with the adhesive 7. In the bonding process, the battery cell 4 and the cooler 6 are thermally connected via the adhesive 7. In the bonding process, the battery cell 4 and the cooler 6 are bonded together by the adhesive 7. In the bonding process, the battery cell 4 is bonded to the portion of the cooler 6 to which the adhesive 7 has been applied. The bonding process includes a lamination process.

[0024] As shown in Figure 6, the bonding process involves bonding the battery cell 4 and the cooler 6 by crushing the adhesive 7 applied to the upper surface of the cooler 6 with the lower surface of the battery cell 4. The bonding process includes the step of crushing the adhesive 7 with the battery cell 4 and the cooler 6.

[0025] As shown in Figure 7, if the adhesive 7 is compressed as expected during the bonding process, the thermal resistance of the adhesive 7 will be as expected. The temperature of the battery cell 4 is raised in order to compress the adhesive 7 as expected during the bonding process. The adhesive 7 is highly heat-dependent. At high temperatures, the viscosity of the adhesive 7 decreases, making it easier to compress. At low temperatures, the viscosity of the adhesive 7 increases, making it more difficult to compress. By raising the temperature of the battery cell 4 in advance during the bonding process, the heat from the battery cell 4 reduces the viscosity of the adhesive 7 when it comes into contact with the adhesive 7, thereby improving the compressibility. As the adhesive 7 is compressed as expected, the thermal resistance of the adhesive layer decreases.

[0026] If the bonding process is carried out without performing the heating process, as shown in Figure 8, the viscosity of the adhesive 7 increases due to the low temperature, and the adhesive 7 may not be able to be compressed as intended. In this case, both the thickness of the adhesive 7 and the contact area between the adhesive 7 and the object to be contacted cannot be achieved.

[0027] As described above, according to the embodiment, by raising the temperature of the battery cell 4, which is the component that crushes the adhesive 7, the viscosity of the adhesive 7 can be reduced by the heat of the battery cell 4 during the bonding process, making it possible to crush the adhesive 7 as intended. As a result, the thermal resistance of the adhesive 7 can be reduced, and the target cooling performance can be achieved when cooling the battery cell 4 with the cooler 6.

[0028] Furthermore, the method for raising the temperature of the battery cell 4 in the heating process is not limited to charging and discharging the battery cell 4. For example, the battery cell 4 may be heated by leaving it in a high-temperature environment, or by using an external heat source such as a heater.

[0029] Furthermore, the heating process and the coating process may be performed in either order, or they may be performed in parallel.

[0030] Furthermore, the cooler 6 may be formed separately from the case 2. The energy storage device 1 may include a cooler 6 installed outside the case 2. In this case, the object to be coated is the lower case 5, not the cooler 6. At the bottom of the lower case 5, adhesive 7 is applied to the inner surface, and a different adhesive is applied to the outer surface. The other adhesive is a thermally conductive silicone-based adhesive. The battery cell 4 is bonded to the inner surface at the bottom of the lower case 5 by adhesive 7. The cooler 6 is bonded to the outer surface at the bottom of the lower case 5 by the other adhesive. In this energy storage device 1, the battery cell 4, adhesive 7, lower case 5, the other adhesive, and the cooler 6 are stacked in that order. [Explanation of Symbols]

[0031] 1. Energy storage device 2 cases 3 Battery Modules 4 battery cells 5 Lower Case 6 Cooler 7 Adhesive

Claims

1. A method for manufacturing an energy storage device comprising a battery and a cooler, A coating process in which a thermally conductive adhesive is applied to the object to be coated, A temperature control step for raising the temperature of the battery, A bonding step in which the battery, whose temperature has been raised, and the object to be coated, to bond the battery and the object to be coated, by sandwiching the adhesive between them, Includes, In the bonding step, the battery and the object to be coated are bonded together with the adhesive, thereby thermally connecting the battery and the cooler via the adhesive. A method for manufacturing an energy storage device, characterized by the following:

2. The object to be coated is the cooler, The cooler is integrally formed with the case that houses the battery. The bonding step includes bonding the battery to the portion of the cooler to which the adhesive has been applied. A method for manufacturing an energy storage device according to claim 1.

3. The object to be coated is a case that houses the battery. The cooler is a hollow cooler integrated into the case, The bonding step includes bonding the battery to the portion of the case to which the adhesive has been applied. A method for manufacturing an energy storage device according to claim 1.

4. The coating step includes applying the adhesive to the case in which the cooler is integrated. The method for manufacturing an energy storage device according to claim 3.

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