JP2023173893A - Spacer for battery cell and battery pack using the same - Google Patents

Abstract

To prevent a rapid increase in weight in a spacer used for a battery pack when the spacer is wrapped to a certain level.SOLUTION: A spacer 51 for a battery arranged between two battery cells 11 (11A and 11B) which face each other comprises a plate-like base part 52 in surface contact with one battery cell 11A, and fixes a plate-like buffer part 53 in contact with the other battery cell 11B to the base part 52. The buffer part 53 includes: a top part 111 that is provided between a pair of fixing parts 101 fixed to the base part 52, and is in contact with the battery cell 11B on a first line L1 to apply a pressure; and a pair of regulation parts 131 that rise on the side of the pair of fixing parts 101. A pair of elastic deformation parts 151 are provided in a region between the regulation part 131 and the top part 111. Each elastic deformation part 151 is elastically deformed to an inward direction at the pressure of the top part 111, and comes into contact with the base part 52 on a second line parallel to the first line L1 and slides with respect to the base part 52.SELECTED DRAWING: Figure 5

Description

The present disclosure relates to a battery cell spacer and a battery assembly using the spacer.

Among electric vehicles (EVs) that run on fossil fuels and do not use internal combustion engines, hybrid vehicles (HVs), battery electric vehicles (BEVs), and plug-in hybrid vehicles (PHVs) use secondary batteries such as lithium-ion batteries as motors. It is used as a power source. Lithium ion batteries have a higher energy density than other secondary batteries, and are therefore suitable as a power source for driving the motor of an electric vehicle.

As shown in Patent Document 1, a secondary battery mounted on an electric vehicle generally takes the form of a so-called assembled battery in which battery cells forming one unit of the battery are stacked. In Patent Document 1, battery cells (cells 3) are stacked and held in a casing C (see paragraph [0035]).

The charging rate of lithium ion batteries can be increased by pressurizing individual stacked battery cells. Furthermore, since battery cells expand due to heat generation, clearance management between two battery cells is required. Therefore, as described in Patent Document 1, an elastically deformable spacer 5 is interposed between the stacked individual battery cells (cells 3), and the individual cells 3 are is held in the casing C (see paragraphs [0012][0035]-[0037][0040]).

The spacer 5 disclosed in Patent Document 1 is made of a flexible metal material bent in a zigzag shape, and is attached to the cell 3 via the pressure plate 6 (paragraphs [0036] [0038], FIG. 4 ( a)-(d), see FIG. 5(a)). Patent Document 1 states, ``The individual elastic forces generated when the spacer 5 is pressurized by the pressure plate 6 and elastically deforms are applied to the cells 3 individually, and these individual elastic forces are aggregated to deform the cell. 3 (see paragraph [0036]).

Patent Document 2 discloses another type of spacer 41. The spacer 41 is made of resin, which is an insulating material, and has a wavy cross-sectional shape (see paragraphs [0021] and [0023], and FIG. 2). The spacer 41 has protrusions (a first protrusion 51 and a third protrusion 53, a second protrusion 52 and a fourth protrusion 54) that protrude toward and contact the stacked battery cells 21A and 21B. There is.

Further, between the third protrusion 53 and the fourth protrusion 54, there are protrusions (fifth protrusion 55, sixth protrusion section 56) is provided (see paragraphs [0028]-[0038], FIG. 3). These fifth protrusions 55 and sixth protrusions 56 are formed in the battery cells 21A and 21B, respectively, when the spacer 41 deforms following the narrowing of the interval between the battery cells 21A and 21B when the battery cells 21 expand. contact (see paragraph [0047], FIG. 4).

Lithium ion batteries such as those described in Patent Documents 1 and 2 have an electrolytic solution filled between positive and negative electrodes. In response, progress is being made in developing all-solid-state batteries (bulk type) that use solid electrolytes instead of electrolytes. All-solid-state batteries are easier to handle than lithium-ion batteries whose electrolyte is a liquid, and they also have superior battery performance. When used in electric vehicles, the cruising distance can be extended and the charging time can be shortened.

A battery pack using an all-solid-state battery is described in Patent Document 3, for example.

The assembled battery described in Patent Document 3 has a plurality of battery cells (battery units 10) stacked together with spacers (heat radiating members 20) interposed therebetween, and a laminate consisting of these battery units 10 and heat radiating members 20 is placed in a case 40. (See paragraph [0025]). The spacer (heat dissipation member 20) has a base layer 21 sandwiched between a pair of elastic layers 22 whose base material is an elastic material such as rubber or elastomer (see paragraphs [0030] and [0033]). As an example of the base layer 21, a structure in which a corrugated thin metal plate 21a2 is provided between a pair of flat metal thin plates 21a1 is shown (see paragraph [0048], FIG. 5).

Japanese Patent Application Publication No. 2008-124033 Japanese Patent Application Publication No. 2017-183071 JP2015-053261A

Spacers used in assembled batteries with lithium-ion batteries and all-solid-state batteries as battery cells include:
(1) Function to apply surface pressure above a certain level to battery cells (2) Function to appropriately adjust gaps between battery cells (3) Function to reduce external vibrations (4) Durability required . These items (1) to (4) are the basic performances required of this type of spacer.

In the invention described in Patent Document 1, a phenomenon occurs in which the load increases rapidly when the spacer (spacer 5) is bent to a certain extent.

Referring to FIG. 4(b) of Patent Document 1, it appears that the spacer 5 can be further bent from this state. However, if the spacer 5 is bent until the bent portions come into contact with each other, then the load should increase rapidly. In this case, an excessive force will be applied to the cell 3, so that the spacer 5 cannot actually be used with such a degree of bending.

For this reason, the spacer 5 of Patent Document 1 has a small stroke, making it difficult to satisfy the above (2). Regarding (3) above, if the spacer 5 is bent more than the state shown in FIG. 4(b), the spring force is expected to decrease, and a good vibration damping effect cannot be expected. Improvement is required.

Even in the invention described in Patent Document 2, a phenomenon occurs in which the load increases rapidly when the spacer (spacer 41) is bent to a certain extent.

As shown in FIG. 4 of Patent Document 2, when the battery cell 21 expands, the spacer 41 deforms following the narrowing of the distance between the battery cells 21A and 21B. The fifth protrusion 55 and the sixth protrusion 56 also contact the battery cells 21A and 21B. However, when the distance between the battery cells 21A and 21B further narrows from this state, the spacer 41 suddenly increases its load and exerts an excessive force on the battery cells 21A and 21B. Therefore, in reality, the spacer 41 cannot be used with such a degree of bending.

Therefore, the spacer 41 of Patent Document 2 also has a small stroke, making it difficult to satisfy the above (2). Regarding (3) above, if the spacer 41 is bent more than the state shown in FIG. 4, the spring force is expected to decrease, and a good vibration damping effect cannot be expected. Improvement is required.

The spacer (heat dissipation member 20) disclosed in Patent Document 3 has a small stroke for the above (2) (see paragraph [0049] of Patent Document 3), and has elasticity for the above (1), (3), and (4). It depends on the body layer 22. Improvement is required.

An object of the present disclosure is to prevent a sudden increase in load when the spacer is bent to a certain extent in a spacer used in an assembled battery.

One embodiment of a battery spacer disposed between two battery cells facing each other includes a plate-shaped base that makes surface contact with one of the battery cells, and a plate-shaped base that is fixed to the base and contacts the other battery cell. a plate-shaped buffer part in contact with the other battery cell, the buffer part being provided between a pair of fixing parts fixed to the base and the pair of fixing parts; a top part that comes into contact with and is pressurized on the line, a pair of restriction parts that stand up on the side of the pair of fixed parts, and a region between each of the pair of restriction parts and the top part, and the a pair of elastically deformable parts that elastically deform inward when pressure is applied to the top part, abut against the base part on a second line parallel to the first line, and slide with respect to the base part; Provided as a buffer element.

In a spacer used in an assembled battery, it is possible to prevent a sudden increase in load when the spacer is bent to a certain extent.

FIG. 1 is a schematic plan view of a schematic configuration of an all-solid-state battery according to the present embodiment. FIG. 2 is an exploded perspective view showing the assembly process of an all-solid-state battery. FIG. 3 is a perspective view showing a part of a spacer repeating the same pattern; FIG. 3 is an enlarged front view of a part of the spacer. FIG. 3 is an enlarged front view showing a part of a spacer installed between two battery cells. FIG. 7 is a front view showing a deformed state of the buffer section when the spacer is pressurized. FIG. 6 is a schematic diagram showing an enlarged view of the region circled by a dashed-dotted line in FIG. 5; A graph showing the relationship between the amount of displacement of the buffer section and the load.

Embodiments will be described based on the drawings. This embodiment is an example of application to a battery pack that employs battery cells made of all-solid-state batteries. The explanation will be based on the following items.
1. Configuration (1) Overall overview (2) Spacer 2. Functions and effects (1) Basic functions (2) Surface pressure application function (3) Gap adjustment function (4) Vibration damping function (5) Durability (6) Others 3. Variations

1. Configuration (1) Overall Overview As shown in FIGS. 1 and 2, the assembled battery 1 stores a plurality of 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 housed in the holder 31 in the stacked state. At this time, since the spacer 51 is elastically deformable in its thickness direction, the stacked battery cells 11 are in a state of being pressurized in the stacking direction within the holder 31.

The battery cell 11 is an all-solid-state battery in which a battery body (all 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 storage container 12. . An electric wire 13 connected to the positive electrode layer and the negative electrode layer is drawn out from the storage container 12 .

(2) Spacer FIG. 3 shows a part of the spacer 51 (see FIG. 2) that repeats the same pattern. For convenience of explanation, the surface viewed from the direction of arrow D1 in FIG. Therefore, FIGS. 4 to 6 are front views of the spacer 51 viewed from the front side. However, FIGS. 4 to 6 do not show the entire spacer 51, but only the minimum unit buffer element ME, which will be described later.

As shown in FIGS. 3 to 5, the spacer 51 includes a base portion 52 that contacts one of the two battery cells 11 facing each other, and a buffer portion 53 that contacts the other one. For convenience of explanation, one battery cell 11 that the base 52 contacts is indicated by the reference numeral 11A, and another one of the battery cells 11 that the buffer section 53 contacts is indicated by the reference numeral 11B.

The base 52 is a rectangular plate-like member that makes surface contact with the battery cell 11A. The base 52 has a flat plate shape in order to make surface contact with the battery cell 11A. However, the base 52 does not need to be a completely flat plate, and may have a portion that protrudes from the same plane as long as it can play the role of the spacer 51.

The buffer portion 53 is a plate-shaped member that is fixed to the base portion 52 and comes into contact with the battery cell 11B. However, the plate-like shape of the buffer portion 53 is different from the base portion 52 and has a wavy shape.

The base portion 52 and the buffer portion 53, which are the two elements constituting the spacer 51, are made of metal, for example. For example, the base portion 52 and the buffer portion 53 can be manufactured from iron, stainless steel, aluminum, copper, alloys containing these, and the like.

What is important in the buffer section 53 is the concept of the above-mentioned minimum unit buffer element ME. Referring to FIG. 3, it can be seen that the buffer portion 53 has four elongated chevron-shaped portions connected to one base portion 52. The fact that more chevron-shaped portions are provided can be easily understood by referring to FIG. 2. Each of these chevron shapes constitutes a minimum unit of buffer element ME. The minimum unit buffer element ME means the minimum component with which the buffer section 53 can perform a buffering effect.

A pair of fixed portions 101, a top portion 111, a pair of restriction portions 131, and a pair of elastic deformation portions 151 constitute the minimum unit buffer element ME.

The pair of fixing parts 101 are parts that are fixed to the base part 52 provided in a region corresponding to both ends of the minimum unit buffer element ME. The fixing part 101 can be fixed to the base part 52 by any method such as welding or bonding with an adhesive.

The top portion 111 is the highest portion provided between the pair of fixed portions 101. As shown in FIG. 5, the top portion 111 contacts the battery cell 11B. At this time, the top portion 111 contacts the battery cell 11B on the first line L1 and is pressurized. The first line L1 is an imaginary line that extends in a direction connecting the front and back surfaces of the spacer 51, and where the top portion 111 comes into contact with the battery cell 11B. When viewed in the direction along the first line L1, that is, from the front side or the back side, the top portion 111 has an arc shape.

The pair of regulating parts 131 rises perpendicularly from the base 52 on the side of the pair of fixing parts 101 and is bent at a right angle. These regulating parts 131 play a role of regulating the deformation of the buffer part 53 so that it does not fall toward the fixed part 101 when the top part 111 is pressurized. The regulating portion 131 is set to a height lower than half of the total height of the top portion 111, and has enough rigidity to prevent the top portion 111 from falling down when pressurized.

The pair of elastic deformation parts 151 are provided in the regions between each of the pair of restriction parts 131 and the top part 111, and are elastically deformed inward when the top part 111 is pressurized. Inward direction here means the direction of the space S surrounded by the base portion 52 and the buffer portion 53. In this specification, the direction of the space S when viewed from the buffer section 53 is called inward, and the direction opposite to the space S is called outward.

As shown in FIG. 6, the elastic deformation part 151 elastically deforms inward when the top part 111 is pressurized and hits the base part 52 on the second line L2 parallel to the first line L1, and and slide. The second line L2 is an imaginary line that extends in a direction parallel to the first line L1, and on which the elastically deformable portion 151 abuts and slides against the base portion 52. The elastic deformation part 151 has a support area 152, an action area 153, and a contact area 154 as a structure for realizing the operation of sliding against the base 52.

As shown in FIGS. 4 to 6 , the support region 152 is a region that extends parallel to the base 52 along the base 52 and communicates with the regulating portion 131 .

The action area 153 is an area that extends diagonally and communicates with the top portion 111 .

The contact region 154 is an inwardly bent shape that connects the support region 152 and the action region 153, and is a region that abuts against the base 52 by elastically deforming the bent portion when the top portion 111 is pressurized.

As shown in FIGS. 2 and 3, the buffer portion 53 joined to the base portion 52 has a plurality of minimum unit buffer elements ME arranged. At this time, the buffer section 53 arranges the minimum unit buffer elements ME so that the first line (see FIG. 5) and the second line (see FIG. 6) of each minimum unit buffer element ME are parallel. ing.

In addition, the minimum unit buffer element ME has the apex 111 located at the center when viewed in the direction along the first line (see FIG. 5) and the second line (see FIG. 6), that is, when viewed from the front side or the back side. It has a bilaterally symmetrical shape.

As described above, the elastically deformable portion 151 is elastically deformed when the top portion 111 is pressurized, abuts against the base portion 52, and slides on the base portion 52. Therefore, the base portion 52 is provided with a low friction region LF in the region on which the contact region 154 of the elastically deformable portion 151 slides. The low friction area LF is an area having a lower coefficient of friction than the surface of the base 52 including its peripheral area.

The low friction region LF is provided, for example, by fixing to the base 52 a low friction member 54 made of a material with a smaller coefficient of friction than the surface of the base 52. If metal is used as the low friction member 54, for example, carbon (coefficient of friction 0.15), antimony (coefficient of friction 0.26), tin (coefficient of friction 0.29), silver (coefficient of friction 0.32) , indium (friction coefficient 0.32), magnesium (friction coefficient 0.34), tellurium (friction coefficient 0.35), etc. can be used. Non-metallic materials such as various PTFE and polyethylene have even lower coefficients of friction, allowing a wider range of materials to be selected.

The low friction region LF can also be achieved by lowering the surface roughness value, as another example. For example, the low friction region LF can be obtained by polishing the region of the base portion 52 on which the contact region 154 of the elastically deformable portion 151 slides.

2. Functions and Effects (1) Basic Functions As shown in FIG. 5, the spacer 51 is interposed between the two battery cells 11 (11A, 11B). As shown in FIG. 6, when the battery cell 11 deforms from this state so as to narrow the gap C between two adjacent battery cells 11, the top 111 of the buffer section 53 is pressurized (arrow a in FIG. ), the buffer portion 53 is deformed so as to be crushed. When the pressure applied to the top 111 increases, the pair of contact areas 154 comes into contact with the base 52, and when the pressure applied to the top 111 further increases, the contact areas 154 slide on the base 52, and the pair of contact areas 154 come into contact with the base 52. The distance between the points that contact the base 52 increases (see arrow b in FIG. 6).

FIG. 7 is a schematic diagram showing an enlarged view of the circled portion in FIG. When the contact area 154 of the buffer part 53 slides on the base 52, since the base 52 has a low friction area LF in its sliding area, the static frictional force and the dynamic frictional force of the contact area 154 with respect to the base 52 are reduced. Both are reduced. This makes it easier for the contact area 154 of the buffer section 53 to move in a direction that increases the distance between the contact points with respect to the base 52 (see arrow b in FIG. 6), and the buffer section 53 is smoothly crushed.

FIG. 8 is a graph showing the load on the spacer 51 with respect to the amount of displacement of the buffer portion 53. As shown in FIG. In the graph of FIG. 8, P is the amount of displacement of the buffer portion 53 when the pair of contact regions 154 come into contact with the base portion 52. At this time, if the contact position of the contact region 154 with respect to the base 52 does not move as in the inventions described in Patent Documents 1 and 2, for example, as shown by the dotted line in FIG. The load increases rapidly. In contrast, in the present embodiment, after the displacement amount of the buffer portion 53 reaches P, the contact area 154 slides with respect to the base 52 (see arrow b in FIG. 6), and the low friction area LF This promotes smooth sliding. As a result, the load on the spacer 51 increases gradually, as shown by the solid line in FIG.

Therefore, according to the present embodiment, in the spacer 51 used in the assembled battery 1, it is possible to prevent a sudden increase in the load when the spacer 51 is bent to a certain extent.
(2) Surface pressure imparting function As can be seen by comparing FIGS. 4 and 5, in the initial state, the spacer 51 connects the two battery cells 11 (11A, 11B) with the buffer part 53 slightly crushed. ) is interposed between. Such a spacer 51 has elasticity in the direction in which the buffer portion 53 approaches or moves away from the base portion 52, and exhibits restoring force. As a result, the battery cells 11 are pressurized in the stacking direction, and surface pressure is applied to the battery cells 11.

Therefore, according to the present embodiment, it is possible to increase the charging rate of the battery cell 11 and improve its efficiency.

(3) Gap Adjustment Function The battery cells 11 expand by generating heat and deform so as to narrow the gap C between two adjacent battery cells 11.

Then, as shown in FIG. 6, the top portion 111 of the buffer portion 53 is pressurized (see arrow a in FIG. 6), and the elastically deformable portion 151 is elastically deformed. At this time, as described above, when the elastic deformation part 151 is largely deformed, its contact area 154 comes into contact with the base 52, and when the pressure applied to the top part 111 increases, the contact area 154 slides on the base 52, The distance between the contact points on the base 52 by the pair of contact areas 154 increases (see arrow b in FIG. 6).

Therefore, according to this embodiment, a good gap adjustment function can be realized.

(4) Vibration damping function The assembled battery 1 is mounted on, for example, an electric vehicle (EV) and serves as a power source for a motor (not shown). Therefore, the assembled battery 1 is placed in an environment where it is constantly exposed to vibrations as the vehicle travels.

In the assembled battery 1 of this embodiment, even if the amount of displacement of the buffer section 53 increases, the elasticity of the spacer 51 is ensured and a sufficient vibration damping effect can be obtained (see FIG. 8). Vibration can be suppressed. As a result, it is possible to prevent damage to various parts caused by continued application of vibrations from the outside, and to suppress inconveniences such as generation of noise.

(5) Durability The spacer 51 of the present embodiment not only has improved durability due to the vibration damping effect of the buffer section 53, but also is configured by the metal base section 52 and the buffer section 53. Therefore, it has inherently high durability.

Therefore, the spacer 51 of this embodiment and the assembled battery 1 using the same have the effect of increasing durability.

(6) Others The buffer element ME, which is the smallest unit, has a symmetrical shape with the top portion 111 in the center. Therefore, the left and right sides are deflected in a well-balanced manner, and it is possible to perform a stable surface pressure application function, gap adjustment function, and vibration damping function.

The top portion 111 of the buffer portion 53 has an arc shape. Therefore, when pressurized, the contact area 154 of the elastically deformable portion 151 can be easily bent inward.

The height of the regulating portion 131 is lower than half of the total height of the top portion 111. Therefore, the rigidity of the regulating portion 131 can be increased, and when the top portion 111 is pressurized, it becomes possible to concentrate the elastic restoring force on the elastically deformable portion 151.

The elastically deformable portion 151 has a shape in which a support region 152 extending parallel to the base 52 and an action region 153 extending diagonally are connected by an inwardly bent contact region 154. Therefore, when the top portion 111 is pressurized, the contact area 154 can be easily bent inward.

3. Modifications Various changes and modifications can be made in implementation.

For example, the shape, size, aspect ratio, etc. of the base portion 52 and the base body 53 constituting the spacer 51 are merely examples, and various modifications and changes can be made in implementation. The shape and size, height-to-width ratio, curvature, etc. of the top portion 111 and the elastically deformable portion 151 of the buffer portion 53 are also the same.

In this embodiment, metal is used as an example of the material for the spacer 51, but the spacer 51 is not limited to metal, and may be made of resin or rubber, for example. At this time, the base 52 and the buffer section 53 that constitute the spacer 51 do not necessarily need to be manufactured from the same material. Various combinations of materials are possible, such as a combination of the buffer part 53 made of.

Although this embodiment shows an example of application to an all-solid-state battery as a battery cell in which a battery cell spacer 51 is interposed, there is no need to limit the implementation to this, and it is applicable to a lithium-ion battery in which an electrolyte is sealed. It may also be applied.

All other variations and changes are permitted in implementation.

1 Battery pack 11, 11A, 11B Battery cell 12 Storage container 13 Electric wire 31 Holder 51 Spacer 52 Base 53 Buffer part 54 Low friction member 101 Fixed part 111 Top part 131 Regulation part 151 Elastic deformation part 152 Support area 153 Action area 154 Contact area C Gap S Space L1 First line L2 Second line LF Low friction area ME Minimum unit buffer element

Claims (9)

A battery spacer disposed between two battery cells facing each other,
a plate-shaped base that makes surface contact with one of the battery cells;
a plate-shaped buffer portion fixed to the base and in contact with another one of the battery cells;
Equipped with
The buffer section is
a pair of fixing parts fixed to the base;
a top portion provided between the pair of fixing portions and pressurized by contacting the other battery cell on a first line;
a pair of regulating parts that stand up on the side of the pair of fixed parts;
Each of the restricting portions is provided in a region between each of the pair of regulating portions and the top portion, and is elastically deformed inwardly when the top portion is pressurized, and is attached to the base portion on a second line parallel to the first line. a pair of elastic deformable parts that abut and slide against the base;
is provided as the minimum unit buffer element,
Spacer for battery cells. The buffer section includes a plurality of the minimum unit buffer elements such that each of the first and second lines is arranged in parallel.
The battery cell spacer according to claim 1. The minimum unit buffer element has a symmetrical shape when viewed from a direction along the first and second lines,
The battery cell spacer according to claim 1. The base includes a low-friction area in which the elastic deformation part slides, the coefficient of friction being lower than that of the surrounding area.
The battery cell spacer according to claim 1. The low friction region is provided with a material having a smaller coefficient of friction than the base.
The battery cell spacer according to claim 4. The low friction area is provided by having a lower surface roughness value than the surrounding area,
The battery cell spacer according to claim 4. The top portion has an arc shape when viewed from a direction along the first and second lines,
The battery cell spacer according to claim 1. The height of the restriction part is lower than half of the total height of the top part.
The battery cell spacer according to claim 7. The elastic deformation portion is
a support region extending along the base and communicating with the restriction portion;
an action area extending diagonally and communicating with the top;
a contact area that connects the support area and the action area in an inwardly bent shape and abuts against the base by elastically deforming the bent part when pressurizing the top;
The battery cell spacer according to claim 8, comprising:

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