JP7028142B2 - Battery pack manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing a battery pack containing a plurality of battery cells.

Conventionally, an assembled battery in which a plurality of battery cells are stacked and connected has been used as a vehicle battery or the like. For example, Patent Document 1 discloses a battery module in which spacers are brought into contact with the side surfaces of each battery cell and arranged, and a plurality of arranged battery cells are collectively restrained by a restraining member.

Japanese Unexamined Patent Publication No. 2014-102939

By restraining with a restraining member, surface pressure can be applied to each battery cell, and battery performance can be improved. However, the thickness of each battery cell varies, and when constrained so as to have a predetermined surface pressure, the thickness of the plurality of battery cells as a whole in the stacking direction also varies. Therefore, for example, when a battery stack in which a predetermined number of battery cells are stacked is constrained to have a predetermined surface pressure and is housed in a battery case of uniform size, the end face of the battery stack and the battery case The size of the gap created between them is different. If shims (corresponding to spacers) of appropriate thickness are inserted into the gaps, the battery stack can be properly restrained, but the adjustment of shim thickness becomes complicated.

The present invention has been made to solve the problems of the above-mentioned conventional techniques. That is, an object of the present invention is to provide a method for manufacturing a battery pack in which a shim capable of appropriately maintaining a restrained state of the battery stack is inserted between the battery case and the battery stack.

The method for manufacturing a battery pack according to one aspect of the present invention, which is aimed at solving this problem, is a method for manufacturing a battery pack in which a battery stack in which a plurality of battery cells are stacked is housed in a battery case to manufacture a battery pack. A restraining step of pressing and restraining the battery stack in the stacking direction, a battery stack inserting step of inserting the restrained battery stack into the battery case, and a first plate-shaped member. The first plate-shaped member is crushed by crushing a shim including a second plate-shaped member and a bag-shaped member provided between the first plate-shaped member and the second plate-shaped member. Inserting a shim to be inserted into the space between the end surface of the battery stack in the stacking direction and the inner wall surface of the battery case facing the end face in a state where the plate-shaped member of No. 1 and the second plate-shaped member are brought close to each other. A step, a separation step of separating the first plate-shaped member and the second plate-shaped member by expanding the bag-shaped member, and a resin being injected into the expanded bag-shaped member to obtain the said It includes a curing step of curing the resin.

According to the method for manufacturing a battery pack in the above aspect, a shim having a bag-shaped member sandwiched between two plate-shaped members is prepared, and after the battery stack is housed in the battery case, the bag-shaped member is crushed 2 A shim in which the plate-shaped members are close to each other is inserted into the battery case. Further, the bag-shaped member is expanded, the two plate-shaped members are separated from each other, and the resin is injected into the bag-shaped member to be cured. As a result, the shims corresponding to the size of the gap between the battery stack and the battery case are arranged in the battery case by the two plate-shaped members and the resin. Therefore, the battery stack is properly restrained by the battery case and the shim.

According to the present invention, a method of manufacturing a battery pack in which a shim capable of appropriately maintaining a restrained state of the battery stack is inserted between the battery case and the battery stack is realized.

It is an exploded perspective view which shows the battery pack of this embodiment. It is explanatory drawing which shows the battery stack. It is a schematic partial sectional view of a battery pack. It is a process drawing which shows the manufacturing method of a battery pack. It is explanatory drawing which shows the shim before insertion. It is explanatory drawing which shows the insertion method of a battery stack. It is explanatory drawing which shows the manufacturing method of the battery pack.

Hereinafter, the embodiment of the present invention will be described in detail with reference to the accompanying drawings. In this embodiment, the present invention is applied to a method for manufacturing a battery pack in which a plurality of battery cells are housed in a battery case.

As shown in the exploded perspective view of FIG. 1, the battery pack 1 of the present embodiment includes two battery stacks 10, a battery case 20, and two shims 30 corresponding to each battery stack 10. In the battery pack 1, the battery stack 10 and the shim 30 are housed in the battery case 20. In this embodiment, the battery case 20 capable of accommodating two battery stacks 10 is used, but the number of battery stacks 10 accommodated in one battery case 20 is not limited to two, and may be one or three. The above is fine.

The battery case 20 of this embodiment is, for example, a box-shaped battery case made of a metal such as aluminum by a die casting method, and has a predetermined rigidity. As shown in FIG. 1, the battery case 20 of the present embodiment has two spaces for accommodating the battery stack 10, and the upper surface of the battery case 20 is open in the drawing. The battery stack 10 and the shim 30 are inserted into the battery case 20 through the upper opening. In the present specification, as shown by an arrow in FIG. 1, the longitudinal direction of the battery stack 10 is the stacking direction, and the vertical direction is defined with the opening side of the battery case 20 as the upper side.

As shown in FIG. 2, the battery stack 10 includes a plurality of battery cells 11, a plurality of insulating members 12, and two end plates 13. As shown in FIG. 2A, each battery cell 11 is a flat, substantially rectangular parallelepiped battery, and both positive and negative electrodes 111 are provided on one of the elongated side surfaces so as to project.

The insulating member 12 is formed of, for example, a resin having an insulating property, and is arranged between the battery cells 11 and outside the battery cells 11 at both ends. In the battery stack 10 of the present embodiment, as shown in FIG. 2B, each battery cell 11 has an insulating member 12 in such an arrangement that the electrodes 111 project to the same side in the upper part of the drawing and the flat surfaces face each other. They are lined up in between. The arrangement direction of the battery cells 11 is the stacking direction. The insulating member 12 may include, for example, a flow path of a cooling member such as air.

The end plate 13 is a plate material having insulating properties and having a predetermined strength. As shown in FIG. 2C, after stacking a predetermined number of battery cells 11 and insulating members 12, end plates 13 are arranged at both ends thereof.

The battery cell 11 of this embodiment is a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery. In such a secondary battery, the progress of deterioration due to repeated charging and discharging can be delayed by pressing the entire flat surface with an appropriate pressure. In the battery pack 1 of the present embodiment, as shown in FIG. 1, the total of the outer dimension x of the battery stack 10 in the stacking direction and the thickness y of the shim 30 in the stacking direction in the restrained state is the inner dimension of the battery case 20. A shim 30 having a thickness y equivalent to z is arranged in the battery case 20. As a result, the battery case 20 and the shim 30 maintain a state in which an appropriate surface pressure is applied to the battery stack 10 without permanently restraining the battery stack 10.

Here, the variation in the inner dimension z of the battery case 20 is within the range of the product tolerance, whereas the outer dimension x in the stacking direction of the battery stack 10 in the restrained state is the variation in the stacking direction of the individual battery cells 11. There is a variation of about ± 10 mm due to variations in thickness and the like. The battery case 20 of the present embodiment has an inner dimension z that is equal to or larger than the maximum value of the outer dimension x of the battery stack 10, and is large enough to be inserted into any battery stack 10. On the other hand, the thickness y of the shim 30 needs to correspond to the difference between the inner dimension z of the battery case 20 and the outer dimension x of the battery stack 10.

A partial cross-sectional view of the battery pack 1 of this embodiment is shown in FIG. As shown in FIG. 3, the shim 30 is integrally formed with a first plate member 31, an intermediate member 32, and a second plate member 33. The first plate member 31 is an example of a first plate-shaped member, and the second plate member 33 is an example of a second plate-shaped member. The first plate member 31 is a plate-shaped member made of PP resin and is in contact with one end plate 13 of the battery stack 10. The intermediate member 32 is a bag-shaped member 321 made of PP resin having a thickness of about 0.1 mm, in which a mixture 322 of silica sand and ABS resin is sealed. The second plate member 33 is a plate-shaped member made of PP resin and is in contact with the inner wall surface of the side surface 21 of the battery case 20.

The thickness y of the shim 30 can be adjusted by the thickness of the intermediate member 32. That is, the mixture is such that the thickness of the intermediate member 32 is obtained by subtracting the outer dimension x of the battery stack 10 and the thickness of the first plate member 31 and the second plate member 33 from the inner dimension z of the battery case 20. 322 is enclosed. In this embodiment, the shim 30 is provided only on one end side of the battery stack 10, but may be provided on the other end side as well.

Since the battery case 20 of this embodiment is manufactured by the die casting method, a draft s of about 1 to 3 degrees is formed on the side surface 21 of the battery case 20 for ease of manufacturing. Further, the boundary portion t between the bottom surface 22 and the side surface 21 of the battery case 20 is a curved surface that draws a smooth curve. Therefore, the second plate member 33 of the shim 30 of the present embodiment has a shape that matches the shape of the side surface 21 of the battery case 20.

Specifically, as shown in FIG. 3, the thickness of the second plate member 33 in the stacking direction gradually increases upward in accordance with the draft s. Further, the lower portion of the second plate member 33 has a curved surface shape that matches the R shape of the boundary portion t. As a result, the shim 30 can be easily upright and the contact area between the first plate member 31 and the battery stack 10 can be increased, so that an appropriate surface pressure can be applied to the battery stack 10.

Next, a manufacturing method for manufacturing the battery pack 1 of the present embodiment will be described with reference to the process diagram of FIG. 4 and the explanatory diagrams of FIGS. 5 to 7. In this embodiment, as shown in FIG. 1, a battery case 20 accommodating two battery stacks 10 is used. Then, in the following procedure, the same steps are performed in parallel or in order for the two battery stacks 10 housed in one battery case 20.

In this embodiment, a battery case 20, two battery stacks 10, two shims 30, and silica sand and ABS resin material for accommodating the bag-shaped member 321 (see FIG. 3) are prepared in advance, respectively. do. The shim 30 at this stage does not contain the mixture 322 (see FIG. 3) of the intermediate member 32. In the shim 30 at this stage, for example, as shown in FIG. 5, the first plate member 31, the second plate member 33, and the bag-shaped member 321 are integrally provided, and the upper end of the bag-shaped member 321 is It is open. Even if the outer dimension x of the battery stack 10 is the minimum, the bag-shaped member 321 can be expanded in the stacking direction to a size sufficient to fill the gap between the battery case 20 and the battery stack 10. It is the size.

In the manufacturing method of this embodiment, first, the battery stack 10 is restrained with an appropriate binding force (step 1 in FIG. 4). Step 1 is an example of a restraint step. Specifically, as shown in FIG. 6, a pair of transfer jigs 100 are provided in the transfer device for transporting the battery stack 10, and the legs 101 of each transfer jig 100 are attached to the outer surface of each end plate 13. It is inserted into the groove 131 formed in. Then, the transfer device applies a pressing force in the direction of bringing the transfer jigs 100 on both sides closer to each other to the battery stack 10. As a result, the battery stack 10 is in a state where an appropriate surface pressure is applied to each battery cell 11.

Next, the battery stack 10 in the restrained state is inserted into the battery case 20 (step 2 in FIG. 4). Step 2 is an example of a battery stack insertion step. Specifically, as shown in FIG. 6, in a state where the battery stack 10 is restrained by the transfer jig 100, the battery stack is brought into contact with the one side surface 21 and the bottom surface 22 of the battery case 20 by the transfer device. Move 10 Since the inner dimension z of the battery case 20 is equal to or larger than the maximum value of the outer dimension x of the battery stack 10, it is easy to insert the battery stack 10 into the battery case 20. The battery case 20 may be moved toward the battery stack 10.

By moving the battery stack 10 closer to one side surface 21 and inserting it into the battery case 20, a gap corresponding to the outer dimension x of the battery stack 10 is created between the battery stack 10 and the other side surface 21. Therefore, the shim 30 is inserted into the gap between the battery stack 10 and the other side surface 21 of the battery case 20 (step 3 in FIG. 4). Step 3 is an example of a shim insertion step. In this step 3, as shown in FIG. 7A, the bag-shaped member 321 is crushed to bring the first plate member 31 and the second plate member 33 closer to each other, and the thickness in the stacking direction is reduced. Insert the shim 30. By reducing the distance between the first plate member 31 and the second plate member 33, the shim 30 can be inserted regardless of the size of the gap.

Next, an air nozzle is inserted into the bag-shaped member 321 of the shim 30 inserted into the battery case 20, and air is blown by an air supply device to expand the bag-shaped member 321 (step 4 in FIG. 4). By expanding the bag-shaped member 321 the first plate member 31 and the second plate member 33 are separated from each other. Step 4 is an example of a separation step. As shown in FIG. 7B, air is blown from the opening of the bag-shaped member 321 to inflate the crushed bag-shaped member 321 and move the first plate member 31 and the second plate member 33. , The distance between the first plate member 31 and the second plate member 33 is increased. As a result, the first plate member 31 comes into contact with the end surface of the battery stack 10, and the second plate member 33 comes into contact with the inner wall surface of the battery case 20. In this step 4, high-temperature air of about 50 ° C. is blown into the bag-shaped member 321 to raise the temperature inside the bag-shaped member 321.

Then, a nozzle for injecting silica sand and a nozzle for spraying ABS resin are inserted into the expanded bag-shaped member 321 and the silica sand and ABS resin are injected by each supply device (step 5 in FIG. 4). As the silica sand, for example, commercially available No. 7 silica sand can be used. The ABS resin supply device sprays the ABS resin liquefied by heating toward the inside of the bag-shaped member 321 at the same time as injecting the silica sand. Since the temperature inside the bag-shaped member 321 has been raised in the previous step, the ABS resin adheres to the silica sand and is injected into the inside of the bag-shaped member 321.

Further, when the temperature of the sprayed ABS resin is lowered, for example, as shown in FIG. 7 (C), the ABS resin is appropriately mixed with the silica sand and the ABS resin is cured, so that the bag-shaped member 321 is formed. It collects inside. Step 5 is an example of a curing step. As a result, the thickness y of the shim 30 can be set to a size that just fills the gap between the end face of the battery stack 10 in the stacking direction and the inner wall surface of the battery case 20. Further, since the resin is mixed to form a lump mixture 322 and cured, even if the bag-shaped member 321 is damaged, the possibility of silica sand leaking is small.

After injecting the silica sand and the ABS resin until the bag-shaped member 321 is full, the opening of the bag-shaped member 321 is sealed (step 6 in FIG. 4). For example, when the position of the upper surface of the mixture 322 is detected by a sensor and the detected position exceeds a predetermined position such as the height of the upper surface of the first plate member 31 or the second plate member 33, the bag-shaped member 321 is full. to decide. Then, for example, as shown in FIG. 7D, the opening of the bag-shaped member 321 is sandwiched between irons 50 at 100 ° C. and welded to seal the bag-shaped member 321. This completes the shim 30 shown in FIG.

After that, the restraint of the battery stack 10 is released (step 7 in FIG. 4). Specifically, the pressing force by the transfer device shown in FIG. 6 is released, the transfer jig 100 is moved upward in the figure, and the leg portion 101 is separated from the end plate 13. This completes the battery pack 1.

In the battery pack 1 of the present embodiment, the thickness y of the shim 30 can be adjusted by the amount of the mixture 322 injected into the bag-shaped member 321. The shim 30 fills the gap between the battery stack 10 and the battery case 20. As a result, even if the outer dimensions x of the battery stack 10 vary, the state in which an appropriate surface pressure is applied to each battery cell 11 is maintained even after the transfer jig 100 is removed.

As described in detail above, according to the manufacturing method of the present embodiment, a shim 30 having a bag-shaped member 321 between the first plate member 31 and the second plate member 33 is prepared, and the bag-shaped member 321 is crushed. Reduce the thickness of the shim 30 and insert it into the battery case 20. Then, after the insertion, the bag-shaped member 321 is expanded, the silica sand and the ABS resin are injected, and the ABS resin is cured inside the bag-shaped member 321. Therefore, a shim 30 having an appropriate thickness can be formed regardless of the size of the gap between the battery case 20 and the battery stack 10. That is, since the battery pack 1 in which the shim 30 having an appropriate thickness is arranged between the side surface 21 of the battery case 20 and the end surface of the battery stack 10 is manufactured, the battery stack 10 is manufactured by the battery case 20 and the shim 30. The battery pack 1 can be manufactured with stable battery performance while the pressed state is maintained. Further, since the shim 30 can be inserted after the battery stack 10 is inserted, it is unlikely that the shim 30 causes a storage failure of the battery stack 10.

Further, in the present embodiment, since the bag-shaped member 321 is sufficiently large, one type of component can handle gaps of various sizes depending on the amount of silica sand to be injected and the ABS resin. That is, it is possible to reduce the number of parts and the cost of parts. As the silica sand and ABS resin that are stably supplied to the market can be used, the battery pack 1 can be stably produced.

Further, according to the manufacturing method of the present embodiment, there is no need to measure the size of the gap into which the shim 30 is inserted and to select the shim according to the size of the measured gap, and the battery pack 1 does not require the trouble. The manufacturing process can be simplified. Further, the manufacturing process can be automated by using an injection device for automatically injecting silica sand or ABS resin and a detection device for detecting the position of the upper surface of the injected silica sand or the like. In the manufacturing process using automated equipment, the worker does not need to approach the equipment, and the safety of the manufacturing process is high.

It should be noted that this embodiment is merely an example and does not limit the present invention in any way. Therefore, as a matter of course, the present invention can be improved and modified in various ways within the range not deviating from the gist thereof. For example, the number of battery cells and the number of rows arranged in the battery case are examples, and are not limited to the example of this embodiment.

Further, in the present embodiment, the shim 30 including the first plate member 31, the second plate member 33, and the bag-shaped member 321 integrally is used, but these may be separate members. That is, each of the three members may be inserted into the gap. However, if they are integrated, they can be inserted all at once, which is preferable because they are easy to manufacture.

Further, in this embodiment, the battery case 20 manufactured by the die casting method is used, but the present invention is not limited to this. Any battery case having appropriate rigidity may be used, and the manufacturing method thereof is not limited.

Further, in the present embodiment, as the second plate member 33, those having different thicknesses at the upper side and the lower side are used, but a plate material having a constant thickness may be used. For example, even if the second plate member 33 is tilted along the inner wall surface of the battery case 20, the shims 30 have different thicknesses above and below depending on the shape of the mixture 322 enclosed in the bag-shaped member 321. Can be done.

Further, in the present embodiment, the opening of the bag-shaped member 321 is sealed in step 6, but it is not necessary to seal the opening. However, it is desirable to seal it because it can surely prevent the outflow of silica sand.

Further, in the present embodiment, after the shim 30 is formed, the restraint of the battery stack 10 is released, but the restraint may be maintained. That is, the battery pack 1 may be further provided with a restraining member. However, in this embodiment, since the surface pressure of the battery stack 10 can be maintained by the shim 30, another restraining member is unnecessary, and it is preferable not to provide the restraining member from the viewpoint of reducing the number of parts.

1 Battery pack 10 Battery stack 11 Battery cell 20 Battery case 30 Sim 31 First plate member 33 Second plate member 321 Bag-shaped member

Claims (1)

It is a method of manufacturing a battery pack that manufactures a battery pack by accommodating a battery stack in which a plurality of battery cells are stacked in a battery case.
The restraint step of pressing and restraining the battery stack in the stacking direction, and
A battery stack insertion step of inserting the restrained battery stack into the battery case, and
The bag-shaped shim comprising a first plate-shaped member, a second plate-shaped member, and a bag-shaped member provided between the first plate-shaped member and the second plate-shaped member. In a state where the first plate-shaped member and the second plate-shaped member are brought close to each other by crushing the member, the end surface of the battery stack in the stacking direction and the inner wall surface of the battery case facing the end surface The shim insertion process to insert in the space between,
A separation step of separating the first plate-shaped member and the second plate-shaped member by expanding the bag-shaped member.
A curing step of injecting resin into the expanded bag-shaped member and curing the resin,
A method of manufacturing a battery pack, which comprises.

Images