JP2020087704A - Manufacturing method for battery pack - Google Patents

Abstract

To provide a manufacturing method for a battery pack where a shim capable of appropriately maintaining a bound state of a battery stack is inserted between a battery case and the battery stack.SOLUTION: A manufacturing method for a battery pack comprises: a binding step of binding a battery stack 10 through pressing in a lamination direction; a battery stack insertion step of inserting the battery stack 10 in a bound state into a battery case 20; a shim insertion step of inserting a shim 30, which includes a first plate member 31, a second plate member 33, and a bag-shaped member 321 between them, into a space between an end surface in the lamination direction of the battery stack 10 and an inner wall surface of the battery case 20 in a state where the first plate member 31 and the second plate member 33 are set close to each other through shrinking of the bag-shaped member 321; a separation step of separating the first plate member 31 and the second plate member 33 by expanding the bag-shaped member 321; and a hardening step of injecting an ABS resin into the bag-shaped member 321 and hardening the ABS resin.SELECTED DRAWING: Figure 7

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 the respective battery cells and arranged side by side, and a plurality of the arranged battery cells are collectively restrained by a restraining member.

JP, 2014-102939, A

By constraining with the constraining member, a surface pressure can be applied to each battery cell, and the battery performance can be improved. However, there are variations in the thickness of each battery cell, and when constrained to have a predetermined surface pressure, the thickness of the plurality of battery cells as a whole also varies in the stacking direction. 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 housed in a battery case of a uniform size, the end surface of the battery stack and the battery case are The size of the gap between them is different. If shims (corresponding to spacers) having appropriate thicknesses are inserted into the gaps, respectively, the restrained state of the battery stack can be appropriately maintained, but the shim thickness adjustment becomes complicated.

The present invention has been made to solve the problems of the above-described conventional techniques. That is, the problem is to provide a method for manufacturing a battery pack in which a shim that can appropriately maintain the restrained state of the battery stack is inserted between the battery case and the battery stack.

A method for manufacturing a battery pack according to an aspect of the present invention made to solve the problem is a method for manufacturing a battery pack in which a battery case is housed in a battery stack in which a plurality of battery cells are stacked. There is a restraining step of restraining the battery stack by pressing it 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, A shim provided with a second plate-shaped member and a bag-shaped member provided between the first plate-shaped member and the second plate-shaped member is used to crush the bag-shaped member by the crushing of the bag-shaped member. Inserting a shim into a space between an end face in the stacking direction of the battery stack and an inner wall surface of the battery case facing the end face in a state where the plate member and the second plate member are close to each other. A step of separating the first plate-shaped member and the second plate-shaped member by expanding the bag-shaped member, and injecting resin into the expanded bag-shaped member, And a curing step of curing the resin.

According to the method of manufacturing a battery pack in the above aspect, a shim in which a bag-shaped member is sandwiched between two plate-shaped members is prepared, and the bag-shaped member is crushed after the battery stack is housed in the battery case. The shim with the plate-shaped members approaching each other is inserted into the battery case. Further, the bag-shaped member is expanded to separate the two plate-shaped members from each other, and resin is injected into the bag-shaped member and cured. As a result, the two plate-shaped members and the resin dispose the shims in the battery case according to the size of the gap between the battery stack and the battery case. Therefore, the battery stack is properly restrained by the battery case and the shim.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the battery pack by which the shim which can maintain the restraint state of a battery stack appropriately is inserted between a battery case and a battery stack is implement|achieved.

It is an exploded perspective view showing the battery pack of this embodiment. It is explanatory drawing which shows a battery stack. It is a schematic partial cross section figure of a battery pack. It is 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 a battery pack.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present embodiment is an application of the present invention 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. The battery pack 1 has a battery stack 10 and a shim 30 housed in a battery case 20. In the present embodiment, the battery case 20 that can accommodate the two battery stacks 10 is used, but the number of the battery stacks 10 accommodated in the one battery case 20 is not limited to 2, and may be 1 or 3. The above is also acceptable.

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

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, an insulating resin, 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. 2(B), each battery cell 11 has an arrangement in which the electrodes 111 protrude to the same side in the upper part of the drawing and the flat surfaces face each other, and the insulating member 12 is provided. They are placed 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 an insulating property and 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 the present embodiment is, for example, 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 sum of the outer dimension x in the stacking direction of the battery stack 10 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 that is equal 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 being permanently restrained by a restraint band or the like.

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 stacking direction of the individual battery cells 11 in the stacking direction. There are variations 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 a size that can 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.

FIG. 3 shows a partial cross-sectional view of the battery pack 1 of this embodiment. 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 member, and the second plate member 33 is an example of a second plate 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 and a mixture 322 of silica sand and ABS resin enclosed therein. 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 the inner dimension z of the battery case 20 minus the outer dimension x of the battery stack 10 and the thicknesses of the first plate member 31 and the second plate member 33. 322 is enclosed. In the present 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.

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 this 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. The lower portion of the second plate member 33 has a curved surface shape that matches the R shape of the boundary portion t. Thereby, the shim 30 can be made to stand 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 chart of FIG. 4 and the explanatory diagrams of FIGS. In this embodiment, as shown in FIG. 1, the battery case 20 that houses the two battery stacks 10 is used. Then, in the subsequent procedure, similar steps are performed in parallel or in sequence for the two battery stacks 10 housed in one battery case 20.

In this embodiment, the battery case 20, the two battery stacks 10, the two shims 30, and the silica sand and the ABS resin material to be housed in the bag-shaped member 321 (see FIG. 3) are prepared in advance. To do. The shim 30 at this stage does not contain the mixture 322 (see FIG. 3) of the intermediate member 32. The shim 30 at this stage is, for example, as shown in FIG. 5, in which 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. Note that 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 even if the outer dimension x of the battery stack 10 is the smallest. It has become large.

In the manufacturing method of the present embodiment, first, the battery stack 10 is brought into a state of being restrained with an appropriate restraining force (step 1 in FIG. 4). Step 1 is an example of a restraining step. Specifically, as shown in FIG. 6, a pair of transfer jigs 100 are provided in a transfer device that transfers the battery stack 10, and the leg portions 101 of each transfer jig 100 are connected to the outer surface of each end plate 13. It is inserted into the groove portion 131 formed in. Then, the transfer device applies a pressing force to the battery stack 10 in a direction to bring the transfer jigs 100 on both sides closer to each other. As a result, the battery stack 10 is in a state in which an appropriate surface pressure is applied to each battery cell 11.

Next, the restrained battery stack 10 is inserted into the battery case 20 (step 2 in FIG. 4). Step 2 is an example of a battery stack inserting step. Specifically, as shown in FIG. 6, with the battery stack 10 being restrained by the transfer jig 100, the transfer device moves the battery stack up to a position where it contacts one side surface 21 and the bottom surface 22 of the battery case 20. 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 inserting the battery stack 10 toward the 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 formed 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 the 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 close to each other, and the thickness in the stacking direction is reduced. Insert the shim 30. By reducing the gap 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 in the battery case 20, and air is blown in by the 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 separating step. As shown in FIG. 7B, by blowing air from the opening of the bag-shaped member 321, the crushed bag-shaped member 321 is inflated, and the first plate member 31 and the second plate member 33 are moved. , The distance between the first plate member 31 and the second plate member 33 is increased. As a result, the first plate member 31 contacts the end surface of the battery stack 10, and the second plate member 33 contacts the inner wall surface of the battery case 20. In 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 silica sand and ABS resin are injected by respective supply devices (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, which is liquefied by heating, toward the inside of the bag-shaped member 321 at the same time as the injection of 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 bag-shaped member 321.

Further, as the temperature of the sprayed ABS resin decreases, for example, as shown in (C) of FIG. 7, the ABS resin is hardened in a state of being appropriately mixed with silica sand, and the bag-shaped member 321 Collect inside. Step 5 is an example of a curing step. Accordingly, the thickness y of the shim 30 can be set to a size that just fills the gap between the end surface of the battery stack 10 in the stacking direction and the inner wall surface of the battery case 20. In addition, since the resin is mixed and cured into a lump of the mixture 322, even if the bag-shaped member 321 is damaged, the possibility that silica sand leaks is small.

After the silica sand and the ABS resin are injected until the bag-shaped member 321 becomes full, the opening of the bag-shaped member 321 is sealed (step 6 in FIG. 4). For example, when the upper surface position of the mixture 322 is detected by the sensor and the detection 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, it is determined that 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 by the iron 50 at 100° C. and welded to seal the bag-shaped member 321. As a result, the shim 30 shown in FIG. 1 is completed.

Then, 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 drawing, and the leg portion 101 is separated from the end plate 13. This completes the battery pack 1.

In the battery pack 1 of this 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 gap between the battery stack 10 and the battery case 20 is filled with the shim 30. As a result, even if the outer dimension x of the battery stack 10 varies, an appropriate surface pressure is maintained on each battery cell 11 even after the transport jig 100 is removed.

As described in detail above, according to the manufacturing method of the present embodiment, the shim 30 having the bag-shaped member 321 is provided between the first plate member 31 and the second plate member 33, and the bag-shaped member 321 is crushed. Then, the thickness of the shim 30 is reduced and the shim 30 is inserted into the battery case 20. After the insertion, the bag-shaped member 321 is unfolded, silica sand and ABS resin are injected, and the ABS resin is cured inside the bag-shaped member 321. Therefore, the 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 formed by the battery case 20 and the shim 30. It is possible to manufacture the battery pack 1 in which the pressed state is maintained and the battery performance is stable. Further, since the shim 30 can be inserted after the battery stack 10 is inserted, the possibility that the shim 30 will cause a storage failure of the battery stack 10 is small.

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

In addition, according to the manufacturing method of the present embodiment, it is not necessary to measure the size of the gap into which the shim 30 is inserted or to select the shim according to the measured size of the gap, and thus the battery pack 1 The manufacturing process can be simplified. Furthermore, the manufacturing process can be automated by using an injection device that automatically injects silica sand or ABS resin, and a detection device that detects the upper surface position of the injected silica sand or the like. In the manufacturing process with automated equipment, workers do not have to approach the equipment, and the manufacturing process is highly safe.

The present embodiment is merely an example and does not limit the present invention. Therefore, naturally, the present invention can be variously improved and modified without departing from the gist thereof. For example, the number of battery cells and the number of columns arranged in the battery case are all examples, and are not limited to the example of the present embodiment.

Further, in the present embodiment, the shim 30 integrally including the first plate member 31, the second plate member 33, and the bag-shaped member 321 is used, but they may be separate members. That is, the three members may be inserted into the gaps. However, if they are integrated, they can be inserted at a time, which is preferable because the manufacturing is easy.

Further, in the present embodiment, the battery case 20 manufactured by the die casting method is used, but the present invention is not limited to this. The battery case may have any suitable rigidity, and the manufacturing method thereof is not limited.

Further, in the present embodiment, the second plate member 33 having different thicknesses at the upper side and the lower side is used, but a plate material having a constant thickness may be used. For example, even if the second plate member 33 is inclined along the inner wall surface of the battery case 20, the shim 30 having different thicknesses on the upper side and the lower side may be formed depending on the shape of the mixture 322 enclosed in the bag-shaped member 321. You can

In addition, in the present embodiment, the opening of the bag-shaped member 321 is sealed in step 6, but it may not be sealed. However, it is desirable to seal it because it can reliably prevent the outflow of silica sand.

Further, in the present embodiment, the constraint of the battery stack 10 is released after the shim 30 is formed, but the constraint may be maintained. That is, the battery pack 1 may further include a restraining member. However, in the present embodiment, since the shim 30 can maintain the surface pressure of the battery stack 10, no other restraint member is required, and it is preferable not to provide the restraint member from the viewpoint of reducing the number of parts.

DESCRIPTION OF SYMBOLS 1 Battery pack 10 Battery stack 11 Battery cell 20 Battery case 30 Shim 31 1st plate member 33 2nd plate member 321 Bag-shaped member

Claims (1)

A battery pack manufacturing method for manufacturing a battery pack in which a battery stack is housed in a battery case, the battery stack comprising:
A restraining step of restraining the battery stack by pressing in the stacking direction,
A battery stack inserting step of inserting the battery stack in a restrained state into the battery case;
A shim having 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 When the first plate-shaped member and the second plate-shaped member are brought close to each other by crushing the member, an end face in the stacking direction of the battery stack and an inner wall surface of the battery case facing the end face are formed. A shim insertion step of inserting in the space between,
A separating 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 a resin into the expanded bag-shaped member and curing the resin,
A method of manufacturing a battery pack, comprising:

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