Battery cell spacer and battery pack using the same

Abstract

To prevent sudden increase in surface pressure applied to a battery cell when a spacer used for a battery pack is bent to some extent.SOLUTION: A spacer 51 arranged between two battery cells 11A, 11B has a base body 52 having a wavy cross-section shape in which peaks and valleys continue. The base body 52 includes a pressure receiving surface 54 that is located at a top of a corrugated shape 53 and being in surface contact with each of the two battery cells 11A, 11B and a buffer unit 55 that alternately connects pressure receiving surfaces 54M, 54V on a mountain side and a valley side to form the corrugated shape 53. The buffer unit 55 alternately gives the corrugated shape 53 a barrel shape having a maximum width of a buckling possible buckled bent unit 56, and provides an arrangement interval for securing an arrangement space of the buckled bent unit 56 between the adjacent buckled bent units 56 on the same surface side.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present disclosure relates to a spacer for a battery cell and a battery pack using the same.

Background Art

[0002] Among electric vehicles (EVs) that do not use an internal combustion engine operating on fossil fuels, hybrid vehicles (HV), battery electric vehicles (BEV), and plug-in hybrid vehicles (PHV) utilize a secondary battery such as a lithium-ion battery as a power source for the motor. Since a lithium-ion battery has a high energy density compared to other secondary batteries, it is suitable as a power source for driving the motor of an electric vehicle.

[0003] As shown in Patent Document 1, a secondary battery mounted on an electric vehicle generally takes the form of a battery pack in which battery cells that form a single unit as a battery are stacked. In Patent Document 1, battery cells (cell 3) are stacked and held in a casing C (see paragraph

[0035] ).

[0004] The charging rate of a lithium-ion battery can be increased by applying pressure to the stacked individual battery cells. Also, since the battery cells expand and contract due to charge / discharge and temperature changes, clearance management between two battery cells becomes necessary. Therefore, as described in Patent Document 1, an elastically deformable spacer 5 is interposed between the stacked individual battery cells (cell 3), and the individual cells 3 are held in the casing C in a state where a compressive force is applied in the stacking direction (see paragraphs

[0012] ,

[0035] -

[0037] ,

[0040] ).

[0005] The spacer 5 disclosed in Patent Document 1 is made of a flexible metal material that is bent in a zigzag shape and is attached to the cell 3 via a pressure plate 6 (see paragraphs

[0036] and

[0038] , and Figures 4(a)-(d) and 5(a)). Patent Document 1 states that "when the spacer 5 is pressed by the pressure plate 6 and undergoes elastic deformation, the individual elastic forces generated are individually applied to the cell 3, and these individual elastic forces combine to apply a pressing force to the cell 3" (see paragraph

[0036] ).

[0006] Patent Document 2 discloses another form of spacer 41. This spacer 41 is made of a resin which is an insulating material and has a corrugated cross-sectional shape (see paragraphs

[0021] and

[0023] , and Figure 2). The spacer 41 has protrusions (first protrusion 51 and third protrusion 53, second protrusion 52 and fourth protrusion 54) that project outwards and make contact with the stacked battery cells 21A and 21B.

[0007] Furthermore, between the third projection 53 and the fourth projection 54, there are projections (fifth projection 55, sixth projection 56) that protrude toward the battery cells 21A and 21B but remain in a non-contact state under normal circumstances (see paragraphs

[0028] -

[0038] , Figure 3). When the battery cell 21 expands, the fifth projection 55 and sixth projection 56 come into contact with the battery cells 21A and 21B respectively as the spacer 41 deforms in accordance with the narrowing of the distance between the battery cells 21A and 21B (see paragraph

[0047] , Figure 4).

[0008] Lithium-ion batteries, as described in Patent Documents 1 and 2, fill the space between the positive and negative electrodes with an electrolyte. In contrast, development is underway on all-solid-state batteries (bulk type) that use a solid electrolyte instead of a liquid electrolyte. All-solid-state batteries are easier to handle and have superior performance compared to lithium-ion batteries, which use a liquid electrolyte. When used in electric vehicles, they can extend the driving range and shorten the charging time.

[0009] A battery pack using all-solid-state batteries is described, for example, in Patent Document 3.

[0010] The battery pack described in Patent Document 3 stacks multiple battery cells (battery units 10) via spacers (heat dissipation members 20), and houses the stack consisting of these battery units 10 and heat dissipation members 20 in a case 40 (see paragraph

[0025] ). The spacers (heat dissipation members 20) sandwich a base layer 21 between a pair of elastic layers 22 made of an elastic material such as rubber or elastomer (see paragraphs

[0030] and

[0033] ). As an example of the base layer 21, a structure is shown in which a corrugated metal sheet 21a2 is provided between a pair of flat metal sheets 21a1 (see paragraph

[0048] , Figure 5). [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Japanese Patent Publication No. 2008-124033 [Patent Document 2] Japanese Patent Publication No. 2017-183071 [Patent Document 3] Japanese Patent Publication No. 2015-053261 [Overview of the project] [Problems that the invention aims to solve]

[0012] Spacers used in battery packs that use lithium-ion batteries or all-solid-state batteries as battery cells include: (1) A function to appropriately adjust the gap between battery cells. (2) Function to apply a constant surface pressure to the battery cell This is what is required. In other words, it is a function that can absorb changes in the gap between battery cells while ensuring a constant surface pressure on the battery cells. In order to satisfy these requirements (1) and (2), it is necessary that even if the spacer bends to a certain extent, the surface pressure on the battery cells does not increase rapidly.

[0013] In the invention described in Patent Document 1, when the spacer (spacer 5) is bent to a certain extent, a phenomenon occurs in which the surface pressure on the battery cell increases rapidly.

[0014] Referring to Figure 4(b) of Patent Document 1, it appears that the spacer 5 could bend further from this state. However, if the spacer 5 were to bend until the bent portions came into contact, the surface pressure would increase rapidly thereafter. This would place an excessive force on the cell 3, so in reality, the spacer 5 cannot be bent to that extent for use.

[0015] Therefore, the spacer 5 in Patent Document 1 has a small stroke and does not adequately satisfy the requirements of (1) and (2) above. Improvement is needed.

[0016] The spacer (heat dissipation member 20) disclosed in Patent Document 3 also has difficulty satisfying requirement (1) above due to its small stroke (see paragraph

[0049] of Patent Document 3), and since it relies solely on the elastic layer 22 for surface pressure application, it also has difficulty satisfying requirement (2) above. Improvement is needed.

[0017] In this regard, in the invention described in Patent Document 2, initially only a group of protrusions (first protrusion 51 and third protrusion 53, second protrusion 52 and fourth protrusion 54) are in contact with the battery cell (see paragraphs

[0029] -

[0038] of Patent Document 2 and Figure 2-3). When the battery cells 21A and 21B expand from this state, the first inclined portion 61 connected to the first protrusion 51 and the second inclined portion 62 connected to the second protrusion 52 buckle, and the protrusions (fifth protrusion 55 and sixth protrusion 56) that normally remained in a non-contact state come into contact with the battery cells 21A and 21B (see paragraphs

[0047] -

[0055] of Patent Document 2 and Figure 4-5).

[0018] Regarding the adoption of the above configuration, Patent Document 2 claims that "...a certain load is applied from the spacer to the battery cell, and even when the battery cell expands, appropriate battery performance is obtained, and the cooling efficiency of the battery cell is maintained at a high level..." (see paragraph

[0012] , etc., of Patent Document 2).

[0019] On the other hand, according to the invention described in Patent Document 2, a plurality of protrusions (the first protrusion 51 and the third protrusion 53, the second protrusion 52 and the fourth protrusion 54, the fifth protrusion 55 and the sixth protrusion 56) are provided, and these protrusions are each given a different role. Therefore, specific characteristics such as unique rigidity must be given to each individual protrusion and the inclined portions connected thereto (see, for example, paragraph

[0053] of Patent Document 2). Further, it cannot stand alone as a spacer, and additional components such as the first rigid body portion 71 and the second rigid body portion 72 are also required (see paragraphs

[0042] -

[0046] of Patent Document 2).

[0020] Therefore, the invention described in Patent Document 2 is accompanied by problems such as complexity of structure, difficulty in design, and complexity of manufacturing and assembly, and improvement is required.

[0021] An object of the present disclosure is to prevent a sudden increase in the surface pressure applied to a battery cell when a spacer used in a laminated battery is bent to a certain extent.

Means for Solving the Problems

[0022] One aspect of a battery spacer disposed between two battery cells facing each other has a cross-sectional shape of a continuous waveform of mountains and valleys, with the surface facing one of the two battery cells being the mountain side surface and the surface facing the other being the valley side surface, a base body, pressure receiving surfaces located at the tops of the waveform shapes of the base body that appear on each of the mountain side surface and the valley side surface and being in surface contact with the two battery cells respectively, and buffer portions that connect the pressure receiving surfaces located on the mountain side surface and the valley side surface alternately to form the waveform shape. The buffer portions alternately give the waveform shape a barrel shape in which the width expands from both ends of the pressure receiving surface to a maximum width with a buckling portion that can buckle and then contracts in width, and provide an arrangement interval that secures an arrangement space for the buckled buckling portions between adjacent buckling portions on the same surface side.

[0023] One aspect of a laminated battery includes a plurality of battery cells housed in a housing-shaped holder in a stacked state and the above-described battery spacer.

Advantages of the Invention

[0024] In a spacer used for a battery pack, it is possible to prevent a sharp increase in the surface pressure applied to a battery cell when the spacer is bent to a certain extent.

Brief Description of the Drawings

[0025] [Figure 1] A schematic diagram showing a plan view of the schematic configuration of the all-solid-state battery according to the present embodiment. [Figure 2] An exploded perspective view showing the assembly process of the all-solid-state battery. [Figure 3] A perspective view of the spacer. [Figure 4] A front view showing an enlarged part of the spacer. [Figure 5] A front view showing an enlarged part of the spacer incorporated between two battery cells. [Figure 6] A front view showing the deformed state of the buffer part when the spacer is pressurized. [Figure 7] A graph showing the relationship between the displacement amount of the buffer part and the surface pressure applied by the spacer to the battery cell.

Embodiments for Carrying Out the Invention

[0026] Embodiments will be described based on the drawings. This embodiment is an application example to a battery pack employing battery cells using all-solid-state batteries. It will be described along the following items.

[0027] 1. Configuration (1) Overall Overview (2) Spacer 2. Operational Effects 3. Modified Examples

[0028] 1. Configuration (1) Overall Overview As shown in Figures 1 and 2, the battery pack 1 houses multiple battery cells 11 in a housing-shaped holder 31. The battery cells 11 are stacked with spacers 51 (battery spacers) interposed in the gap C between two adjacent battery cells 11, and are housed in the holder 31 in this stacked state. At this time, since the spacers 51 are elastically deformable in the thickness direction, the stacked battery cells 11 are pressed in the stacking direction within the holder 31.

[0029] The battery cell 11 is an all-solid-state battery in which a battery body (all components not shown) having a structure in which a solid electrolyte layer is sandwiched between a positive electrode layer and a negative electrode layer is housed in a flat rectangular container 12. Wires 13 connected to the positive electrode layer and the negative electrode layer are drawn out from the container 12.

[0030] (2) Spacer Figure 3 is a perspective view of a spacer 51 (see Figure 2) with a repeating pattern. For the sake of explanation, the view from the direction of arrow D1 in Figure 3 is considered the front of the spacer 51, and the view from the direction of arrow D2 is considered the side of the spacer 51. Therefore, Figures 4 to 6 are front views of the spacer 51 as seen from the front. Figures 4 to 6 do not show the entire spacer 51, but rather enlarged views of a part of it. Of these, Figures 5 and 6 show the spacer 51 interposed between two battery cells 11 (11A, 11B) facing each other.

[0031] As shown in Figures 3 to 6, the spacer 51 is mainly composed of a base body 52 having a corrugated cross-sectional shape with continuous peaks and valleys when viewed from the front. The base body 52 is made of, for example, rubber and has a rectangular shape that is the same size and shape as the battery cells 11 (11A, 11B). One side of the base body 52 is the peak side 51M facing the battery cell 11A, and the opposite side is the valley side 51V facing the battery cell 11B.

[0032] However, the designations of the mountain side 51M and the valley side 51V are merely convenient terms used to distinguish and refer to both sides of the spacer 51. The mountain side 51M and the valley side 51V do not necessarily have to possess attributes that are inherent in the meaning of the words mountain and valley.

[0033] The base body 52, which has a corrugated cross-sectional shape, exhibits an overall corrugated shape 53 when viewed from the front. In this embodiment, for the sake of explanation, the concept of a corrugated shape is denoted by reference numeral 53. The corrugated shape 53 does not refer to a specific structure or its elements, but rather to the conceptual shape of the base body 52 itself.

[0034] When viewed from the mountain side 51M, the waveform shape 53 has a peak that forms the position of maximum amplitude, and this portion is the pressure-receiving surface 54 on the mountain side. When viewed from the valley side 51V, the waveform shape 53 has a peak that forms the position of maximum amplitude, and this portion is the pressure-receiving surface 54 on the valley side. For the sake of explanation, the pressure-receiving surface 54 on the mountain side is called the pressure-receiving surface 54M, and the pressure-receiving surface 54 on the valley side is called the pressure-receiving surface 54V.

[0035] The two pressure-receiving surfaces 54M and 54V are flat surfaces with a certain area, and are positioned to make surface contact with the two battery cells 11A and 11B.

[0036] The base body 52 is equipped with a buffer section 55 that connects two types of pressure-receiving surfaces 54M and 54V, one for the peak side and the other for the valley side, thereby creating a buffering effect on the base body 52. ​​The buffer section 55 connects the two types of pressure-receiving surfaces 54M and 54V, one for the peak side and the other for the valley side, in an alternating manner, forming a wave shape 53.

[0037] More specifically, the buffer portion 55 widens from both ends of the pressure-receiving surface 54 and bends in a tapering direction with the bent portion 56 being the widest point, giving the corrugated shape 53 a barrel shape. The barrel shape is applied alternately to the peak side 51M and the valley side 51V.

[0038] An important aspect of this embodiment is that the bent portion 56 can buckle when the gap C between two adjacent battery cells 11A and 11B narrows and the spacer 51 is compressed. The bent portion 56 buckles when the pressure received by the pressure-receiving surface 54 on the peak side and the pressure-receiving surface 54V on the valley side exceeds a certain range, deforming the barrel shape of the buffer portion 55 into a flatter shape. This buckling of the bent portion 56 is achieved by the shape of the bent portion 56 and the barrel shape of the buffer portion 55.

[0039] When the bent portion 56 buckles, the buffer portion 55 expands to its maximum width. Therefore, if there is no space between adjacent buffer portions 55 and the bent portions 56, the bent portions 56 cannot be buckled. Thus, the buffer portion 55 provides an arrangement interval I (see Figure 4) between adjacent bent portions 56 on the same side to ensure space for the buckled bent portions 56.

[0040] Figure 4 shows the dimensions and angles of each part of the uncompressed spacer 51. The dashed line represents the virtual surface VS of the battery cells 11A and 11B, which are in surface contact with the pressure-receiving surfaces 54M and 54V on both sides of the spacer 51, respectively.

[0041] Figure 4 shows the angle θ, length L, width W, and spacing I. The angle θ is the angle of the buffer portion 55 that slopes in a direction that increases the width from both sides of the pressure-receiving surface 54, that is, the angle with respect to a line perpendicular to the virtual plane VS. The length L is the length from the end of the pressure-receiving surface 54 to the bent portion 56. The width W is the width of the pressure-receiving surface 54 when the spacer 51 is viewed from the front. The spacing I is, as mentioned above, the distance between adjacent bent portions 56 on the same side.

[0042] The angle θ is 15 to 25 degrees, for example, 20 degrees. This angle is set so that buckling occurs at the appropriate timing when the spacer 51 is compressed by two battery cells 11A and 11B that are spaced close together. If the angle θ is too large, the bent portion 56 will buckle relatively early when the spacer 51 is compressed, and the surface pressure that the spacer 51 applies to the battery cells 11A and 11B via the pressure-receiving surface 54 will be insufficient. Conversely, if the angle θ is too small, the bent portion 56 will not be able to buckle, and only normal compressive deformation will occur in the buffer portion 55. From this perspective, the angle θ is set to 15 to 25 degrees, for example, 20 degrees.

[0043] The ratio of the width W of the pressure-receiving surface 54 to the length L from the end of the pressure-receiving surface 54 to the bent portion 56 is set in the range of 1:0.9 to 1:1.1, for example, 1:1. To simply increase the surface pressure applied to the battery cells 11A and 11B, one could narrow the width W of the pressure-receiving surface 54. However, if the width W of the pressure-receiving surface 54 is narrowed, the spacing I between adjacent bent portions 56 will narrow, causing the bent portions 56 to come into contact with each other prematurely and hindering the buckling action. From this perspective, the ratio of width W to length L is set in the range of 1:0.9 to 1:1.1, for example, 1:1.

[0044] The ratio of the spacing I between adjacent bent portions 56 to the length L from the end of the pressure-receiving surface 54 to the bent portion 56 is set to a range of 1:1.5 to 1:2.5, for example, 1:2.

[0045] 2. Effects As shown in Figure 5, the spacer 51 is interposed between the two battery cells 11 (11A, 11B), absorbing changes in the gap C between the battery cells 11A and 11B while applying a constant surface pressure to the battery cells 11A and 11B. Therefore, according to this embodiment, a gap adjustment function can be realized, and the charge level of the battery cells 11 can be increased, thereby improving their efficiency.

[0046] Figure 7 is a graph showing the relationship between displacement and surface pressure, with the displacement of the buffer portion 55 on the horizontal axis and the surface pressure exerted by the spacer 51 on the battery cells 11A and 11B on the vertical axis. This graph shows the values ​​of two types of samples that fall within the range of the spacer 51 in this embodiment. In both samples, it can be seen that in the first stage section A1, from a state where the displacement of the buffer portion 55 is zero until it reaches X1, the surface pressure exerted by the spacer 51 on the battery cells 11A and 11B gradually increases.

[0047] As shown in Figure 6, when the battery cell 11 expands due to heat generation or other reasons, the gap C between two adjacent battery cells 11A and 11B narrows. As a result, the pressure-receiving surfaces 54M and 54V located on the peak side 51M and valley side 51V of the spacer 51 are pressurized, causing the buffer portion 55 to deform as if being crushed, and its barrel shape to become flatter.

[0048] At this time, when the pressure applied to the pressure-receiving surfaces 54M and 54V exceeds a certain value, the bending portion 56 of the buffer portion 55 buckles. In the graph of Figure 7, the displacement of the buffer portion 55 at this time is represented by X1. As shown in the graph of Figure 7, when the displacement of the buffer portion 55 exceeds X1 and the bending portion 56 buckles, the increase in surface pressure that the spacer 51 applies to the battery cells 11A and 11B becomes gradual. This is because the force that the buffer portion 55 applies to the outside weakens due to the buckling of the bending portion 56.

[0049] Section A2, the second stage in which the increase in surface pressure becomes gradual, continues until the displacement of the buffer section 55 reaches X2. In this section A2, the buffer section 55 is crushed while the bent section 56 is buckled, deforming the barrel shape into a flatter shape.

[0050] Figure 6 shows the state just before adjacent bent portions 56 come into contact with each other. If the buffer portion 55 is further compressed from this state, adjacent bent portions 56 will come into contact with each other, resisting the force that tries to crush the buffer portion 55. The displacement amount X2 in the graph of Figure 7 shows the displacement amount of the buffer portion 55 at the point when adjacent bent portions 56 come into contact with each other. When the displacement amount exceeds X2, the third stage section A3 is entered, and in this section A3, the surface pressure that the spacer 51 exerts on the battery cells 11A and 11B increases sharply.

[0051] According to this embodiment, in the spacer 51 used in the battery pack 1, the surface pressure applied to the battery cells 11A and 11B can be gradually increased in section A1 and slowly increased in section A2. Therefore, when the spacer 51 is bent to a certain extent, a sudden increase in the surface pressure applied to the battery cells 11A and 11B can be prevented.

[0052] 3. Variant Various modifications and changes are possible during implementation.

[0053] For example, the shape, size, and aspect ratio of the base 52 constituting the spacer 51 are merely examples, and various modifications and changes are possible during implementation. The same applies to the shape and size, height-to-width ratio, and curvature of the pressure-receiving surface 54 and the buffer portion 55, as well as the angle θ, length L, width W, and spacing I shown in Figure 4.

[0054] In this embodiment, rubber is used as an example material for the spacer 51, but in practice, the material is not limited to rubber. For example, metals such as iron, stainless steel, aluminum, copper, and alloys containing these may be used, or resin may be used.

[0055] In this embodiment, an example is shown where the peak side 51M faces the battery cell 11A and the valley side 51V faces the battery cell 11B. However, the opposite configuration is also possible, where the valley side 51V faces the battery cell 11A and the peak side 51M faces the battery cell 11B.

[0056] This embodiment demonstrates an application example to an all-solid-state battery as a battery cell interposed with a spacer 51 for the battery cell, but the implementation is not limited to this, and it may also be applied to a lithium-ion battery that contains an electrolyte.

[0057] Any modifications or changes are permitted during implementation. [Explanation of Symbols]

[0058] 1 battery pack 11, 11A, 11B battery cells 12 Storage containers 13 Electric wire 31 Holder 51 Spacer (Battery Spacer) 51M mountain side 51V valley side 52 Base 53 Waveform shape 54, 54M, 54V pressure receiving surface 55 Buffer section 56. Flexed section C Gap A1 First stage section A2 Second stage section A3 Third stage section VS Virtual Face

Claims

1. A battery spacer that is placed between two battery cells facing each other, A base having a corrugated cross-sectional shape with continuous peaks and valleys, with the surface facing one of the two battery cells being the peak side and the surface facing the other being the valley side, A pressure-receiving surface located at the peak of the wave-shaped form of the base body appearing on the mountain side and the valley side, respectively, and making surface contact with the two battery cells, A buffer section that forms the wave shape by connecting the pressure-receiving surfaces located on the mountain side and the valley side in an alternating manner, Equipped with, The aforementioned buffer portion is From both ends of the pressure-receiving surface, barrel-shaped sections are given alternately to the corrugated shape, with the width increasing and the width decreasing to the maximum width of the buckling-capable bendable section. To provide spacing between adjacent bent portions on the same side, ensuring space for the buckled bent portions to be placed. Battery spacer.

2. The angle at which the buffer portion is inclined from both ends of the pressure-receiving surface in a direction that increases its width is 15 to 25 degrees. Battery spacer according to claim 1.

3. The angle at which the buffer portion is inclined from both ends of the pressure-receiving surface in a direction that increases its width is 20 degrees. Battery spacer according to claim 1.

4. The angle at which the buffer portion is inclined from both ends of the pressure-receiving surface in a direction that increases its width is set to the angle at which the bent portion buckles when the distance between the two battery cells narrows. Battery spacer according to claim 1.

5. The ratio of the width of the pressure-receiving surface to the length from the pressure-receiving surface to the bent portion is set to a range of 1:0.9 to 1:1.

1. A battery spacer according to any one of claims 1 to 4.

6. The ratio of the width of the pressure-receiving surface to the length from the pressure-receiving surface to the bent portion is set to 1:

1. A battery spacer according to any one of claims 1 to 4.

7. The ratio of the spacing between adjacent bent portions on the same side to the length from the pressure-receiving surface to the bent portion is set to a range of 1:1.5 to 1:2.

5. A battery spacer according to any one of claims 1 to 4.

8. The ratio of the spacing between adjacent bent portions on the same side to the length from the pressure-receiving surface to the bent portion is set to 1:

2. A battery spacer according to any one of claims 1 to 4.

9. Multiple battery cells are stored in a stacked state within a housing-shaped holder, A battery spacer is placed between two battery cells facing each other, Equipped with, The aforementioned battery spacer is A base having a corrugated cross-sectional shape with continuous peaks and valleys, with the surface facing one of the two battery cells being the peak side and the surface facing the other being the valley side, A pressure-receiving surface located at the peak of the wave-shaped form of the base body appearing on the mountain side and the valley side, respectively, and making surface contact with the two battery cells, A buffer section that forms the wave shape by connecting the pressure-receiving surfaces located on the mountain side and the valley side in an alternating manner, Equipped with, The aforementioned buffer portion is From both ends of the pressure-receiving surface, barrel-shaped sections are given alternately to the corrugated shape, with the width increasing and the width decreasing to the maximum width of the buckling-capable bendable section. To provide spacing between adjacent bent portions on the same side, ensuring space for the buckled bent portions to be placed. Battery pack.

10. The aforementioned battery cell is an all-solid-state battery. The battery pack according to claim 9.

Images