Charging and discharging device including a spacer for an air bag supporting a battery cell

Abstract

The present technology relates to a charging and discharging device including a spacer for supporting an air bag unit of a battery cell, and according to the present technology, it is possible to prevent interference of the air bag unit between battery cells during a formation process of the battery cells and increase space utilization of the air bag unit.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2020-0139948, filed on October 27, 2020, and the entire contents of the Korean Patent Application are incorporated herein by reference.

[0002] The present invention relates to a charging and discharging device including a spacer of an air bag unit for supporting a battery cell. Background Art

[0003] Generally, according to the shape of the secondary battery, the secondary battery can be divided into a cylindrical type, a prismatic type, a pouch type, etc. Here, since the pouch type secondary battery is formed by using a pouch outer material composed of a multilayer film including a metal layer (foil) and a synthetic resin layer coated on the upper and lower surfaces of the metal layer, the weight of the battery can be significantly reduced compared to a cylindrical or square shape using a metal can, which enables the battery to be lightweight and changed into various forms.

[0004] In such a pouch-type secondary battery, an electrode assembly is placed in a stacked form. An electrode tab and an electrode lead are connected to the electrode assembly, and the electrode lead protrudes from the outer material of the pouch. Such an electrode lead is electrically connected to an external device through a contact point, and is supplied with power from the external device.

[0005] The pouch-type secondary battery (hereinafter referred to as a "battery cell") is manufactured by a process of assembling a cell and a process of activating the battery, and in the battery activation step, the battery cell is mounted on a charging and discharging device, and charging and discharging are performed as a necessary condition for activation. As described above, the process of performing a predetermined charge / discharge using a charging and discharging device in order to activate the battery cell is called a formation process.

[0006] In order to perform such a formation process of the battery cell, the battery cell should be properly mounted on the charging and discharging device. That is, the electrode lead of the battery cell needs to be placed to contact the conductive part of the charging and discharging device so that the battery cell and the charging and discharging device are electrically connected, and the electrical connection state should be maintained while charging and discharging are performed.

[0007] For this purpose, the charging and discharging device of the secondary battery generally includes a plurality of compression plates for fixing the battery cells. In a state where each battery cell is inserted between two compression plates, charging is performed by applying current through the leads of the battery cell while applying pressure from both sides.

[0008] Similarly, by using a pressing plate to push the battery cell, it is possible to suppress the increase in the thickness of the battery cell due to gas generation during the charging and discharging process. At this time, the generated gas is collected in the airbag unit and then removed after the formation process. Here, the airbag unit is a part of the bag outer material that extends in a direction perpendicular to the electrode lead in the monomer body part that is pressed during the formation process, and can be cut out in the bag outer material later.

[0009] Figure 1 Schematic diagram showing a compression plate in a conventional secondary battery charging and discharging device. Figure 1 , a conventional secondary battery charging and discharging device 10 includes pressing plates 12 which are arranged at regular intervals to have spaces for inserting battery cells 11 and which are movable to reduce intervals between the pressing plates 12, and a spacer 13 having a curved surface is coupled to the pressing plates 12.

[0010] When each battery cell 11 is loaded into the space between the extrusion plates 12, the spacer 13 connected to the extrusion plates 12 guides the battery cell 11 to guide the battery cell 11 into the space for cell insertion, and the spacer 13 supports the airbag unit of the battery cell 11, thereby preventing interference of the airbag units between adjacent battery cells 11 during the formation process of the battery cell 11.

[0011] Figure 2a is a photograph showing the shape of an air bag during a formation process of a battery cell in a conventional secondary battery charging and discharging device, and Figure 2b is a photograph showing the shape of the airbag after the formation process of the battery cell. Figure 2a-2b It is seen that, in the airbag of the battery cell, the area contacting the spacer is not sufficiently bulged. That is, because the conventional spacer has a convex-shaped frame, the space utilization of the airbag unit is reduced.

[0012] Therefore, there is a need for a secondary battery charging and discharging device including a spacer capable of increasing space utilization of an airbag unit. Summary of the invention

[0013] Technical issues

[0014] The present invention is believed to solve at least some of the above problems. For example, aspects of the present invention provide a secondary battery charging and discharging device including a spacer capable of preventing airbag unit interference between battery cells during a formation process of the battery cells and increasing space utilization of the airbag unit.

[0015] Technical Solution

[0016] The present invention provides a charging and discharging device including a spacer for supporting an airbag unit of a battery cell. In one example, a charging and discharging device according to the present invention includes: n extrusion plates (n is an integer equal to or greater than 2); and at least one spacer, the at least one spacer being connected to one end of each of the extrusion plates and supporting the airbag unit of the battery cell. Here, the spacer includes a first surface and a second surface opposite to each other, and the first surface and the second surface are concavely curved in directions opposite to each other.

[0017] In one example, the height L of the spacer corresponds to or is greater than the length of the airbag unit. In a specific example, the spacer has points L1, L5, and L9 in the height direction of the spacer, and the thicknesses of L1, L5, and L9 satisfy the following conditions 1 and 2:

[0018] [Condition 1]

[0019] L1>L5

[0020] [Condition 2]

[0021] L9>L5

[0022] Here, L1 is a point corresponding to 1 / 10 of the total height of the spacer, L5 is a point corresponding to 5 / 10 of the total height of the spacer, and L9 is a point corresponding to 9 / 10 of the total height of the spacer.

[0023] In one example, the thickness of the spacer at point L5 corresponds to 0.2 to 0.7 times the thickness of the spacer at point L1 or point L9. More specifically, the thickness of the spacer may gradually decrease from point L1 to point L5, and the thickness of the spacer may gradually decrease from point L9 to point L5.

[0024] In another example, the spacer has a frame structure and includes an elastic pressing member at a center point between the first surface and the second surface. In a specific example, the elastic pressing member is a coil spring, a leaf spring or rubber.

[0025] In yet another example, the spacer includes a protective layer at the outer sides of the first surface and the second surface. In a specific example, the protective layer includes at least one selected from the group consisting of silicone, soft plastic, and soft foam.

[0026] Furthermore, a spacer is coupled to one end of each of the extruded plates, and a plurality of spacers may be coupled to the extruded plates along the length of the extruded plates.

[0027] [Beneficial Effects]

[0028] According to the charging and discharging device including the spacer for supporting the airbag unit of the battery cell of the present invention, it is possible to increase the space utilization rate of the airbag unit of the battery cell by including the spacer having a structure corresponding to the shape of the airbag unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic diagram showing a compression plate in a conventional secondary battery charging and discharging device.

[0030] Figure 2a is a photograph showing the shape of an air bag during a formation process of a battery cell in a conventional secondary battery charging and discharging device, and Figure 2b is a photograph showing the shape of the airbag after the formation process of the battery cell.

[0031] Figure 3 is a schematic diagram showing a charging and discharging apparatus according to one embodiment of the present invention.

[0032] Figure 4 is a schematic diagram showing a state in which a plurality of battery cells are arranged in a charging and discharging device according to one embodiment of the present invention.

[0033] Figure 5 is a schematic diagram showing a spacer in a charging and discharging device according to another embodiment of the present invention.

[0034] Figure 6 is a schematic diagram showing a spacer in a charging and discharging device according to still another embodiment of the present invention.

[0035] Figure 7 is a schematic diagram showing a spacer in a charging and discharging device according to still another embodiment of the present invention. DETAILED DESCRIPTION

[0036] Since the present invention allows various changes and multiple embodiments, specific embodiments will be shown in the drawings and described in detail in the text. However, this is not intended to limit the invention to the specific form disclosed, and should be understood to include all changes, equivalents and substitutions included in the spirit and scope of the invention.

[0037] In this application, it should be understood that terms such as "including" or "having" are intended to indicate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and these terms do not preclude the possibility of the presence or addition of one or more other features or numbers, steps, operations, components, parts, or combinations thereof. Moreover, when a part such as a layer, film, region, plate, etc. is referred to as being "on" another part, this includes not only the case where the part is "directly" "on" another part, but also the case where another other part is interposed therebetween. On the other hand, when a part such as a layer, film, region, plate, etc. is referred to as being "under" another part, this includes not only the case where the part is "directly" "under" another part, but also the case where another other part is interposed therebetween. In addition, in this application, "placed on..." may include the case where it is placed at the bottom as well as at the top.

[0038] The present invention relates to a charging and discharging device including a spacer of an air bag unit for supporting a battery cell.

[0039] Generally, a charging and discharging device used in a formation process of a battery cell includes a pressing plate that is arranged at regular intervals to have a space for inserting a battery cell, and the pressing plate is movable to reduce the interval between the pressing plates, and a spacer having a curved surface is connected to the pressing plate. When each battery cell is loaded into the space between the pressing plates, the spacer guides the battery cell to guide the battery cell into the space for cell insertion, and the spacer supports the airbag unit of the battery cell, thereby preventing interference of the airbag unit between adjacent battery cells. However, because the conventional spacer has a convex-shaped frame, the airbag unit contacting the spacer is not sufficiently raised, which reduces the space utilization of the airbag unit.

[0040] Thus, the present invention provides a charging and discharging device including a spacer that can prevent interference of an airbag unit between battery cells and increase space utilization of the airbag unit. Specifically, since the area of ​​the spacer that contacts the airbag unit has a structure corresponding to the structure of the airbag unit, the space utilization of the airbag unit of the battery cell can be increased.

[0041] Hereinafter, a charging and discharging device including a spacer of an air bag unit for supporting a battery cell will be described in detail.

[0042] In one example, a charging and discharging device according to the present invention includes: n pressing plates (n is an integer equal to or greater than 2); and at least one spacer, the at least one spacer being coupled to one end of each of the pressing plates. At this time, the spacer includes a first surface and a second surface opposite to each other, and the first surface and the second surface are concavely curved in directions opposite to each other.

[0043] Typically, during the formation process, the battery cell may bulge due to the generation of gas or the expansion of the positive electrode plate and the negative electrode plate. At this time, the compression plate prevents the bulge by squeezing the battery cell during the formation process. Specifically, in the charging and discharging device according to the present invention, n compression plates are arranged at regular intervals and are configured to be movable so that the intervals can be increased or decreased. That is, the battery cell is arranged between the kth compression plate and the (k+1)th compression plate (k is equal to or greater than 1 and equal to or less than n-1), and the kth compression plate and the (k+1)th compression plate move in the direction of squeezing the two surfaces of the battery cell, thereby squeezing the battery cell.

[0044] In addition, the n extrusion plates are connected in a manner allowing translational movement along an axis extending in the lower portion, a gear is connected to one end of the axis, and a drive motor may be connected to the gear. Here, any mechanical combination may be used as long as it has a drive mechanism capable of moving each extrusion plate in a direction of extruding the battery cells.

[0045] The battery cell is a pouch-type unit cell, and an electrode assembly having a positive electrode / separator / negative electrode structure is embedded in the outer material of the laminate sheet in a state of being connected to an electrode lead formed outside the outer material of the laminate sheet. The electrode lead may be led out to the outside of the laminate sheet and may extend in the same or opposite directions to each other.

[0046] For convenience of explanation, the drawings of the present invention only show a pouch-type battery cell in a form in which a pair of electrode leads are drawn out in opposite directions, but the battery cell applied to the battery module according to the present invention is not particularly limited thereto, and a pair of electrode leads may be drawn out in the same direction. Here, the pouch-type battery cell may include an airbag unit.

[0047] In one example, the n extruded plates may be made of a metal material having high mechanical rigidity so that the n extruded plates do not deform under high heat and pressure. For example, aluminum or stainless steel may be used. However, the material of the extruded plate is not limited to a metal material, and the extruded plate may also be made of reinforced plastic, reinforced ceramic, or tempered glass. In addition, the charging and discharging device according to the present invention includes n extruded plates. Here, n may be in the range of 2 to 100, 2 to 50, 2 to 30, 2 to 20, 2 to 15, or 2 to 10.

[0048] In one example, a battery cell including an airbag unit in an inactive state is transported by a pickup facility and then inserted into the space between the extrusion plates. At this time, although not shown in the accompanying drawings, a slide sheet is provided to protect the body surface of the battery cell against the extrusion plate when it is extruded while supporting the battery cell so that the battery cell is positioned at a predetermined height. The slide sheet has a sheet form. One side of the slide sheet is connected to the kth extrusion plate, the other side of the slide sheet is connected to the (k+1)th extrusion plate, and the slide sheet is folded in the space between the kth extrusion plate and the (k+1)th extrusion plate for battery cell insertion. That is, one slide sheet can be used for every two extrusion plates. A general slide sheet can be used for the charging and discharging device according to the present invention, and its detailed description is omitted here.

[0049] In one example, a battery cell accommodated between corresponding compression plates has an airbag unit at an upper portion, and a spacer coupled to each compression plate supports the airbag unit. At this time, the spacer includes a first surface and a second surface opposite to each other, and the first surface and the second surface are concavely curved in directions opposite to each other, thereby easily supporting the airbag unit of the activated battery cell.

[0050] In a specific example, a battery cell is arranged between the kth extrusion plate and the (k+1)th extrusion plate. At this time, the first surface of the spacer connected to the (k+1)th extrusion plate and the second surface of the spacer connected to the kth extrusion plate support the airbag unit of the battery cell. Here, the height L of the spacer corresponds to or is greater than the length of the airbag unit. For example, the height L of the spacer corresponds to the length of the airbag unit. That is, by having a structure corresponding to the shape of the airbag unit in an activated state, the first surface and the second surface of the spacer can increase the space utilization of the airbag unit of the battery cell.

[0051] In another example, in the charging and discharging device of the present invention, the height of the spacer connected to the pressing plate corresponds to the length of the airbag unit. Specifically, the spacer has points L1, L5, and L9 in the height direction of the spacer, and the thicknesses of L1, L5, and L9 satisfy the following conditions 1 and 2:

[0052] [Condition 1]

[0053] L1>L5

[0054] [Condition 2]

[0055] L9>L5

[0056] Here, L1 is a point corresponding to 1 / 10 of the total height of the spacer 230, L5 is a point corresponding to 5 / 10 of the total height of the spacer, and L9 is a point corresponding to 9 / 10 of the total height of the spacer 230. This means that the thickness of the spacer at point L5 is less than the thickness of the spacer at points L1 and L9. Here, the thickness of the spacer at point L5 corresponds to 0.2 to 0.7 times the thickness of the spacer at point L1 or point L9. Specifically, the thickness of the spacer at point L5 corresponds to 0.3 to 0.6 times or 0.4 to 0.5 times the thickness of the spacer at point L1 or L9. For example, the thickness of the spacer at point L5 corresponds to 0.4 times the thickness of the spacer at point L1. Here, the thickness of the spacer means the spacing or distance between the first surface and the second surface.

[0057] In a specific example, the thickness of the spacer may gradually decrease from point L1 to point L5, and the thickness of the spacer may gradually decrease from point L9 to point L5. For example, the cross section of the spacer has a structure similar to that of a concave lens. The spacer is used to increase the space utilization of the airbag unit when the battery cell is activated.

[0058] In yet another example, the spacer may have a frame structure. In this case, the elastic extrusion member may be included in the center point between the first surface and the second surface. Specifically, the elastic extrusion member may be installed at point L5 in the height direction of the spacer. In addition, one side of the elastic extrusion member may be connected to the first surface of the spacer, and the other end of the elastic extrusion member may be connected to the second surface of the spacer.

[0059] In a specific example, the elastic pressing member may be a component that applies a constant pressure in the direction of placing the airbag unit. The elastic pressing member is a coil spring, a leaf spring, or rubber. For example, the elastic pressing member may be a coil spring. The coil spring is a spring having a force that resists a compressive force, and refers to a compression spring.

[0060] That is, since the elastic pressing member is included in the spacer, it is possible to easily support the airbag unit of the battery cell and maintain the shape between the first surface and the second surface of the spacer.

[0061] In yet another example, the spacer includes a protective layer.In a specific example, the spacer includes a protective layer at an outer side of the first surface and the second surface.

[0062] The protective layer is used to prevent damage to the airbag unit of the battery cell contacting the spacer, and may include at least one selected from the group consisting of silicone, soft plastic, and soft foam. For example, a silicone pad may be coated on the first and second surfaces of the spacer.

[0063] In one example, the spacer can be made of a nylon-type plastic material or a fiber-reinforced plastic material having excellent heat resistance and strength. In addition, the spacer is coupled to one end of each of the extruded plates, and a plurality of spacers can be coupled to the extruded plate along the length of the extruded plate. In the accompanying drawings, one extruded plate is shown to have 4 spacers, but this has been determined in consideration of the length of the loaded battery cell, and the number and spacing of the spacers can be changed according to the length of the battery cell.

[0064] [Detailed description of preferred embodiments]

[0065] Hereinafter, various forms of a charging and discharging device including a spacer of an air bag unit for supporting a battery cell will be described in detail with reference to the accompanying drawings.

[0066] (First embodiment)

[0067] Figure 3 is a schematic diagram showing a charging and discharging apparatus according to one embodiment of the present invention.

[0068] refer to Figure 3 , a charging and discharging device 100 according to the present invention includes: n pressing plates 120 (n is an integer equal to or greater than 2); and at least one spacer 130, the at least one spacer 130 being coupled to one end of each of the pressing plates. At this time, the spacer 130 includes a first surface 131 and a second surface 132 opposite to each other, wherein the first surface 131 and the second surface 132 are concavely curved in directions opposite to each other.

[0069] During the formation process, the battery cell may bulge due to gas generation or expansion of the positive electrode plate and the negative electrode plate. At this time, the compression plate 120 prevents the bulge by squeezing the battery cell during the formation process. Specifically, in the charging and discharging device 100 according to the present invention, n compression plates 120 are arranged at regular intervals and are configured to be movable so that the intervals can be increased or decreased. That is, the battery cell is arranged between the kth compression plate and the (k+1)th compression plate (k is equal to or greater than 1 and equal to or less than n-1), and the kth compression plate and the (k+1)th compression plate move in the direction of squeezing the two surfaces of the battery cell, thereby squeezing the battery cell.

[0070] Although not shown in the drawings, the n extrusion plates 120 are connected in a manner allowing translational movement along an axis extending in the lower portion, a gear is connected to one end of the axis, and a drive motor may be connected to the gear. Here, any mechanical combination may be used as long as it has a drive mechanism capable of moving each extrusion plate 120 in a direction of extruding the battery cells.

[0071] As described above, the battery cell including the air bag unit in the inactive state is transported by the pickup facility and then inserted into the space between the pressing plates 120. At this time, although not shown in the drawings, a slide sheet is provided to protect the body surface of the battery cell against the pressing plates 120 when being pressed while supporting the battery cell so that the battery cell is positioned at a predetermined height. A detailed description thereof will be omitted.

[0072] The battery cell accommodated between the corresponding pressing plates 120 has an airbag unit at an upper portion, and the airbag unit is supported by a spacer 130 coupled to each pressing plate 120. At this time, the spacer 130 includes a first surface 131 and a second surface 132 opposite to each other, wherein the first surface 131 and the second surface 132 are concavely curved in directions opposite to each other, thereby easily supporting the airbag unit of the activated battery cell.

[0073] Figure 4 is a schematic diagram showing a state in which a plurality of battery cells are arranged in a charging and discharging device according to one embodiment of the present invention.

[0074] refer to Figure 4 , one battery cell 110 is disposed between the kth pressing plate 120 and the (k+1)th pressing plate 120. At this time, a first surface of the spacer 130 coupled to the (k+1)th pressing plate 120 and a second surface of the spacer 130 coupled to the kth pressing plate support the airbag unit 111 of the battery cell.

[0075] In particular, the height L of the spacer 130 corresponds to the length of the airbag unit 111, and the first surface 131 and the second surface 132 of the spacer 130 can increase the space utilization of the airbag unit 111 of the battery cell 110 by having a structure corresponding to the shape of the airbag unit 111 in the activated state. In addition, it is shown that the charging and discharging device 100 according to the present invention includes 7 extrusion plates 120, but the present invention is not limited to this example. Specifically, the charging and discharging device 100 according to the present invention includes n extrusion plates. Here, n can be in the range of 2 to 100, 2 to 50, 2 to 30, 2 to 20, 2 to 15, or 2 to 10.

[0076] (Second embodiment)

[0077] Figure 5 is a schematic diagram showing a spacer in a charging and discharging device according to another embodiment of the present invention.

[0078] refer to Figure 5 In the charging and discharging device of the present invention, the height of the spacer 230 connected to the pressing plate corresponds to the length of the airbag unit. Specifically, the spacer 230 has points L1, L5, and L9 in the height direction of the spacer, and the thicknesses of L1, L5, and L9 satisfy the following conditions 1 and 2:

[0079] [Condition 1]

[0080] L1>L5

[0081] [Condition 2]

[0082] L9>L5

[0083] Here, L1 is a point corresponding to 1 / 10 of the total height of the spacer 230, L5 is a point corresponding to 5 / 10 of the total height of the spacer, and L9 is a point corresponding to 9 / 10 of the total height of the spacer 230. This means that the thickness of the spacer 230 at point L5 is less than the thickness of the spacer 230 at points L1 and L9. Here, the thickness of the spacer 230 at point L5 corresponds to 0.2 to 0.7 times the thickness of the spacer 230 at point L1 or point L9. For example, the thickness of the spacer 230 at point L5 corresponds to 0.4 times the thickness of the spacer 230 at point L1. Here, the thickness of the spacer 230 means the interval or distance between the first surface 231 and the second surface 232.

[0084] In addition, the thickness of the spacer 230 may gradually decrease from point L1 to point L5, and the thickness of the spacer may gradually decrease from point L9 to point L5. Specifically, the cross section of the spacer 230 has a structure similar to that of a concave lens. The spacer 230 is used to increase the space utilization of the airbag unit when the battery cell is activated.

[0085] (Third Embodiment)

[0086] Figure 6 is a schematic diagram showing a spacer in a charging and discharging device according to still another embodiment of the present invention.

[0087] refer to Figure 6, the spacer 330 has a frame structure. Here, the elastic extrusion member 340 is included in the central area between the first surface 331 and the second surface 332. Specifically, the elastic extrusion member 340 is installed at a point L5 in the height direction of the spacer 330. One side of the elastic extrusion member 340 may be coupled to the first surface 331 of the spacer 330, and the other end of the elastic extrusion member 340 may be coupled to the second surface 332 of the spacer 330.

[0088] Specifically, the elastic pressing member 340 may be a coil spring. Since the elastic pressing member 340 is included in the spacer 330 , it is possible to easily support the airbag unit of the battery cell and maintain the shape between the first surface 331 and the second surface 332 of the spacer 330 .

[0089] (Fourth embodiment)

[0090] Figure 7 is a schematic diagram showing a spacer in a charging and discharging device according to still another embodiment of the present invention.

[0091] refer to Figure 7 , the spacer 430 includes a protective layer 450. The protective layer 450 is formed at the outer sides of the first surface 431 and the second surface 432 of the spacer 430. Specifically, the protective layer 450 is used to prevent damage to the airbag unit of the battery cell contacting the spacer 430, and the silicone pad is coated on the first surface 431 and the second surface 432 of the spacer 430.

[0092] Although the preferred examples of the present invention have been described with reference to the accompanying drawings, it will be understood that those skilled in the art can make various modifications and changes to the present invention without departing from the spirit and scope of the invention as set forth in the appended claims.

[0093] Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

[0094] Description of Reference Numerals

[0095] 10,100: Charging and discharging device

[0096] 11, 110: Battery cells

[0097] 111: Airbag unit

[0098] 12,120: Extruded plate

[0099] 13, 130, 230, 330, 430: spacers

[0100] 131, 231, 331, 431: First surface

[0101] 132, 232, 332, 432: Second surface

[0102] 340: Elastic extrusion member

[0103] 450: Protective layer

Claims

1. A charging and discharging device, include: n extrusion plates; at least one spacer coupled to one end of each of the pressed plates and supporting an air bag unit of a battery cell, wherein the spacer comprises a first surface and a second surface opposite to each other, wherein the first surface and the second surface are concavely curved in directions opposite to each other, wherein n is an integer equal to or greater than 2, and wherein the spacer has points L1, L5 and L9 in the height direction of the spacer, and Among them, the thickness of L1, L5 and L9 meets the following conditions 1 and 2: [Condition 1] L1>L5 [Condition 2] L9>L5 Among them, the L1 is a point corresponding to 1 / 10 of the total height of the spacer, the L5 is a point corresponding to 5 / 10 of the total height of the spacer, and the L9 is a point corresponding to 9 / 10 of the total height of the spacer.

2. The charging and discharging device according to claim 1, in, The height L of the spacer corresponds to or is greater than the length of the airbag unit.

3. The charging and discharging device according to claim 1, in, The thickness of the spacer at the point L5 corresponds to 0.2 to 0.7 times the thickness of the spacer at the point L1 or the point L9.

4. The charging and discharging device according to claim 1, in, The thickness of the spacer gradually decreases from the point L1 to the point L5 , and the thickness of the spacer gradually decreases from the point L9 to the point L5 .

5. The charging and discharging device according to claim 1, in, The spacer has a frame structure and includes an elastic pressing member at a center point between the first surface and the second surface.

6. The charging and discharging device according to claim 5, in, The elastic pressing member is a coil spring, a leaf spring or rubber.

7. The charging and discharging device according to claim 1, in, The spacer includes a protective layer at outer sides of the first surface and the second surface.

8. The charging and discharging device according to claim 7, in, The protective layer includes at least one selected from the group consisting of silicone, soft plastic, and soft foam.

9. The charging and discharging device according to claim 1, in, The spacer is coupled to one end of each of the extruded plates, and a plurality of spacers are coupled to the extruded plates along the length of the extruded plates.

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