JP2022148080A - battery module - Google Patents

Abstract

To provide a battery module capable of suppressing deterioration of a battery performance.SOLUTION: A battery module 10 comprises: a plurality of battery cells 1 laminated in a lamination direction; a spacer 20 that is provided between the two battery cells 1 adjacent to each other in the lamination direction. Each battery cell 1 viewed from the lamination direction includes a rectangular shape. A dimension in a long side direction of each battery cell 1 in a surface vertical to the lamination direction is 1.5 times or more the dimension in a short side direction of each battery cell 1. A thickness of the spacer 20 is gradually reduced toward a central part 27 from an upper end part 26, and is gradually increased toward a lower end part 28 from the central part 27. The thickness in the upper end part 26 of the spacer 20 is 1.3 times of or more the thickness of the central part 27, and the thickness in the lower end part 28 is 1.3 times or more the thickness in the central part 27.SELECTED DRAWING: Figure 3

Description

The present disclosure relates to battery modules.

International Publication No. 2011/158341 (Patent Document 1) discloses an assembled battery in which a plurality of unit cells and a plurality of contact members are alternately stacked. When the contact member is viewed from above, it is curved so as to be concave at the center.

WO2011/158341

In a wide-shaped large-sized battery, the amount of swelling at the central portion of the battery tends to increase as charging and discharging are repeated. Depending on the thickness of spacers provided between a plurality of battery cells, there is a possibility that deterioration of battery performance may be caused.

The present disclosure proposes a battery module capable of suppressing deterioration of battery performance.

A battery module according to the present disclosure includes a plurality of battery cells stacked in the stacking direction, and a spacer provided between two battery cells adjacent in the stacking direction. A battery cell viewed in the stacking direction has a rectangular shape. The dimension in the long side direction of the battery cell in the plane perpendicular to the stacking direction is 1.5 times or more the dimension in the short side direction of the battery cell. The thickness of the spacer gradually decreases from the first edge in the short side direction of the battery cell toward the central portion in the short side direction of the battery cell, and from the central portion of the battery cell to the second edge in the short side direction of the battery cell. gradually increase toward The thickness of the spacer at the first edge is at least 1.3 times the thickness at the center, and the thickness at the second edge is at least 1.3 times the thickness at the center.

Even in the case of a wide-shaped battery with a large amount of expansion, the uniformity of the load distribution can be improved by adjusting the thickness of the spacer, so deterioration of the battery performance can be suppressed.

According to the battery module according to the present disclosure, deterioration of battery performance can be suppressed.

It is a perspective view which shows schematic structure of a battery cell. 4 is a graph showing the relationship between battery cell shape and swelling. 1 is a cross-sectional view showing a schematic configuration of a battery module; FIG. FIG. 3 is a schematic diagram showing an enlarged spacer between battery cells. FIG. 4 is a schematic diagram showing an enlarged spacer at the end of the battery module. 4 is a graph showing a range of aspect ratios of battery cells to which the concept of the embodiment can be applied;

Embodiments will be described below with reference to the drawings. In the following description, the same reference numerals are given to the same parts. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

FIG. 1 is a perspective view showing a schematic configuration of a battery cell 1. FIG. The battery cell 1 includes a substantially rectangular parallelepiped battery case 2 having an opening on the upper surface, and a lid 3 that closes the opening of the battery case 2 . The lid 3 is provided with external terminal portions 4 , 4 . One of the external terminal portions 4 is a positive electrode external terminal, and the other of the external terminal portions 4 is a negative electrode external terminal. The entire circumference of the lid 3 is welded to the opening of the battery case 2 . As a result, the inside of the battery case 2 is sealed.

An electrode assembly (not shown) is accommodated in the battery case 2 . The electrode body has a sheet-like positive electrode, a sheet-like negative electrode, and a sheet-like separator interposed between the positive electrode and the negative electrode. The battery case 2 also contains an electrolyte (not shown).

The X direction shown in FIG. 1 is the thickness direction of the battery cells 1 and indicates the stacking direction of the battery cells 1 in the battery module 10 described later. The battery cell 1 seen in the stacking direction has a rectangular shape. The Y direction indicates the long side direction of the battery cells 1 viewed in the stacking direction. The Y direction is also referred to as the width direction of the battery cell 1 . The Z direction indicates the short side direction of the battery cell 1 viewed in the stacking direction. The Z direction is also referred to as the height direction of the battery cell 1 . The X, Y and Z directions are orthogonal to each other.

A dimension A shown in FIG. 1 is a dimension in the height direction of the battery cell 1 . A dimension B is a dimension in the width direction of the battery cell 1 . A dimension B is a dimension in the long side direction of the battery cell 1 in a plane perpendicular to the stacking direction. The dimension A is the dimension in the short side direction of the battery cell 1 in a plane perpendicular to the stacking direction. The ratio of the dimension in the width direction to the dimension in the height direction of the battery cell 1, that is, B/A is referred to as an aspect ratio in this specification.

A battery central portion 5 virtually shown in FIG. 1 indicates the central portion of the battery cell 1 viewed in the stacking direction.

FIG. 2 is a graph showing the relationship between the shape of the battery cell 1 and swelling. The horizontal axis of the graph shown in FIG. 2 indicates the aspect ratio of the battery cell 1 in the plane perpendicular to the stacking direction of the battery cell 1 . The vertical axis of the graph shown in FIG. 2 indicates the amount of swelling in the stacking direction of the battery cell 1 at the position of the battery central portion 5 after 500 cycles of repeating charging and discharging of the battery cell 1. .

In the battery cell 1, by repeating charging and discharging, the charge density of the electrode mixture is lowered and the surface of the active material is coated with a film. As a result, swelling of the battery cell 1 occurs in the thickness direction (X direction) of the battery cell 1 . As shown in FIG. 2, the swelling of the battery cell 1 tends to increase as the aspect ratio increases. This is because the large aspect ratio reduces the moment force in the cross-sectional direction at the position of the battery central portion 5 , so that the electrodes tend to swell.

When the amount of swelling of the battery central portion 5 is large, the load acting on the battery central portion 5 increases, and the electrolytic solution is discharged to the outside of the battery case 2 . may decrease. An increase in battery resistance in the battery cell 1 leads to local battery deterioration.

The battery module 10 according to the embodiment is for solving this phenomenon. FIG. 3 is a cross-sectional view showing a schematic configuration of the battery module 10. As shown in FIG. As shown in FIG. 3 , the battery module 10 includes multiple battery cells 1 and multiple spacers 20 . In the example shown in FIG. 3, five battery cells 1 arranged in the stacking direction (X direction) are illustrated, but it goes without saying that the number of battery cells 1 included in the battery module 10 is arbitrary. be.

The plurality of spacers 20 include inter-battery spacers 22 provided between two adjacent battery cells in the stacking direction and end spacers 24 provided at both ends of the stack of battery cells 1 .

A stack of battery cells 1 and spacers 20 shown in FIG. 3 is arranged between a pair of end plates (not shown). A pair of end plates are integrally connected by a restraining band (not shown). The restraint band prevents the distance between the pair of end plates from increasing. Therefore, the stack of the battery cells 1 and the spacers 20 is restrained from increasing in length in the stacking direction by the pair of end plates and the restraining band.

Each spacer 20 has a rectangular shape that is substantially the same as the shape of the battery cell 1 when viewed in the stacking direction. Each spacer 20 has an upper edge 26 that is one edge in the height direction (Z direction) of the battery cell 1 and a lower edge that is the other edge in the height direction (Z direction) of the battery cell 1. It has a portion 28 and a central portion 27 forming a central portion in the height direction (Z direction) of the battery cell 1 . The upper edge 26 corresponds to the first edge of the embodiment. The lower edge 28 corresponds to the second edge of the embodiment.

FIG. 4 is a schematic diagram showing an enlarged inter-battery spacer 22 that is the spacer 20 between the battery cells 1. As shown in FIG. The dimension of the spacer 20 in the X direction, which is the stacking direction of the battery cells 1, is also referred to as the thickness of the spacer 20. As shown in FIG. Inter-battery spacer 22 has thickness T1 at upper edge 26 , thickness T2 at central portion 27 , and thickness T3 at lower edge 28 .

The thickness T1 of the upper edge portion 26 is greater than the thickness T2 of the central portion 27 over the entire width direction of the battery cell 1 (the Y direction shown in FIG. 1; in FIG. 4, the direction perpendicular to the paper surface). The thickness T2 of 27 is smaller than the thickness T3 of the lower edge 28 . The thickness of the inter-battery spacer 22 gradually decreases from the upper edge portion 26 toward the central portion 27 and gradually increases from the central portion 27 toward the lower edge portion 28 . The thickness T1 of the upper edge portion 26 and the thickness T3 of the lower edge portion 28 may be equal. In the inter-battery spacer 22, the thickness T1 at the upper edge portion 26 is 1.3 times or more the thickness T2 at the central portion 27, and the thickness T3 at the lower edge portion 28 is 1.3 times or more the thickness T2 at the central portion 27. It is formed as it is.

The inter-battery spacer 22 shown in FIG. 4 has a thickness that continuously decreases from the upper edge portion 26 toward the central portion 27 and continuously decreases from the lower edge portion 28 toward the central portion 27. formed. Inter-battery spacer 22 may have one or more steps on its surface, and may be formed such that the steps become smaller intermittently from upper edge 26 and lower edge 28 toward central portion 27 .

The thickness T1 of the upper edge portion 26 and the thickness T3 of the lower edge portion 28 of the inter-battery spacer 22 may be 30 times or less the thickness T2 of the central portion 27 . If the thickness ratio between the upper edge portion 26 and the lower edge portion 28 and the central portion 27 exceeds 30, the processing of the inter-battery spacer 22 becomes difficult, and the effect of suppressing deterioration of battery performance becomes small.

FIG. 5 is a schematic diagram showing an enlarged end spacer 24 that is the spacer 20 at the end of the battery module 10 . The end spacers 24 have a thickness T4 at the upper edge 26, a thickness T5 at the central portion 27, and a thickness T6 at the lower edge 28. FIG.

The thickness T4 of the upper edge portion 26 is greater than the thickness T5 of the central portion 27 over the entire width direction of the battery cell 1 (the Y direction shown in FIG. 1; in FIG. 5, the direction perpendicular to the paper surface). The thickness T5 of the central portion 27 is smaller than the thickness T6 of the lower edge portion 28 . The thickness of the end spacers 24 tapers from the top edge 26 to the central portion 27 and tapers from the central portion 27 to the bottom edge 28 . The thickness T4 of the upper edge portion 26 and the thickness T6 of the lower edge portion 28 may be equal. In the end spacer 24, the thickness T4 at the upper edge 26 is 1.3 times or more the thickness T5 at the central portion 27, and the thickness T6 at the lower edge 28 is 1.3 times or more the thickness T5 at the central portion 27. It is formed as it is.

The end spacers 24 shown in FIG. 5 have a thickness that continuously decreases from the upper edge 26 toward the central portion 27 and continuously decreases from the lower edge 28 toward the central portion 27 . formed. End spacer 24 may be formed to have one or more steps on its surface, with the steps decreasing intermittently from upper edge 26 and lower edge 28 toward central portion 27 .

The thickness T4 of the upper edge portion 26 and the thickness T6 of the lower edge portion 28 of the end spacers 24 may be 30 times or less the thickness T5 of the central portion 27 . If the thickness ratio between the upper edge portion 26 and the lower edge portion 28 and the central portion 27 exceeds 30, the processing of the end spacers 24 becomes difficult, and the effect of suppressing deterioration of battery performance becomes small.

In addition to defining the thickness of spacer 20 in the height direction of battery cell 1 as described above, the thickness of spacer 20 in the width direction of battery cell 1 may be adjusted. The thickness of both edge portions in the width direction of the spacer 20 may be larger than the thickness of the central portion of the spacer 20 in the width direction. The spacer 20 may have a shape in which the central portion is recessed with respect to the four edges.

The thickness of the spacer 20 may gradually decrease from one edge toward the center in the width direction and gradually increase from the center toward the other edge. The thickness of the spacer 20 at one edge in the width direction may be 1.3 times or more the thickness at the central portion. The thickness of the spacer 20 at the other edge in the width direction may be 1.3 times or more the thickness at the central portion. The thickness of both edge portions in the width direction of the spacer 20 may be equal to each other.

FIG. 6 is a graph showing a range of aspect ratios of battery cells 1 to which the concept of the embodiment can be applied. The horizontal axis of the graph shown in FIG. 6 indicates the aspect ratio of the battery cell 1 in the plane perpendicular to the stacking direction of the battery cell 1, as in FIG. The vertical axis of the graph shown in FIG. 6 indicates the ratio between the thickness of the edge portions (upper edge portion 26 and lower edge portion 28) of the spacer 20 and the thickness of the central portion 27. As shown in FIG.

The concept of the embodiment is based on the premise that it is applied to the battery module 10 in which the aspect ratio of the battery cells 1 is 1.5 or more. If the aspect ratio of the battery cell 1 is less than 1.5, the swelling of the battery cell 1 is less likely to increase, so that the effect of suppressing deterioration in battery performance cannot be sufficiently obtained. Further, since it is difficult to process the spacers 20 corresponding to the battery cells 1 having an aspect ratio exceeding 10, the aspect ratio of the battery cells 1 to which the concept of the embodiment is applied is set to 10 or less.

The curve shown in the graph of FIG. 6 indicates the lower limit of the spacer 20 thickness ratio. Since the ratio of the aspect ratio of the battery cell 1 to the thickness of the spacer 20 does not correspond to 1:1, the curve shown in the graph of FIG. It should be noted that it does not show a function of .

Even if the thickness of the edge portion of the spacer 20 is greater than the thickness of the central portion 27, if the difference between the thickness of the edge portion of the spacer 20 and the thickness of the central portion 27 is small, that is, the thickness of the edge portion of the spacer 20 is thicker than the thickness of the central portion. If the thickness is slightly larger than the thickness of the portion 27, the effect of the embodiment cannot be sufficiently obtained. As already described, by setting the thickness of the edge portion of the spacer 20 to be 1.3 times or more the thickness of the central portion 27, it is possible to obtain the effect of suppressing deterioration in battery performance.

In the battery module 10 having the configuration described above, the dimension in the long side direction (Y direction) of the battery cells 1 in the plane perpendicular to the stacking direction (X direction) is equal to the short side direction (Z direction) of the battery cells. ), and the battery cell 1 has a wide shape. The thickness of the inter-battery spacers 22 provided between the wide-shaped battery cells 1 gradually decreases from the upper edge portion 26 toward the central portion 27 and gradually increases from the central portion 27 toward the lower edge portion 28. . In the inter-battery spacer 22, the thickness of the upper edge portion 26 is 1.3 times or more the thickness of the central portion 27, and the thickness of the lower edge portion 28 is 1.3 times or more the thickness of the central portion 27. formed.

In a wide-shaped large-sized battery having a large aspect ratio and high energy density, the amount of swelling during a long-term cycle tends to increase locally in the battery central portion 5 (FIG. 1) of the battery cell 1 . By adjusting the thickness of the inter-battery spacers 22 in the height direction of the battery cells 1, the uniformity of the load distribution acting on the battery cells 1 in the height direction of the battery cells 1 can be improved. As a result, a decrease in the amount of electrolyte in the battery case 2 can be suppressed, and an increase in battery resistance in the battery cell 1 can be suppressed, thereby suppressing deterioration in battery performance.

In the above-described embodiment, an example in which the thickness of the spacer 20 is adjusted to equalize the load distribution acting on the battery cell 1 has been described. The spacer 20 may be formed so that the region corresponding to the battery central portion 5 with a large swelling amount has a smaller spring constant than other regions. By configuring the center portion of the spacer 20 to be easily deformable as the battery center portion 5 expands, the load acting on the battery cell 1 from the edge portion of the spacer 20 and the load acting on the battery cell 1 from the center portion of the spacer 20 are reduced. The effect of being able to improve the uniformity of the load acting on is also obtained.

In the embodiment, a prismatic battery having a substantially rectangular parallelepiped battery case 2 has been described as an example. The battery cell 1 is not limited to a rectangular battery, and may be a pouch-type battery provided with a flat exterior material made of an aluminum laminate packaging material in place of the battery case 2 .

The embodiments disclosed this time are illustrative in all respects and should be considered not restrictive. The scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all modifications within the meaning and range of equivalents of the scope of the claims.

Reference Signs List 1 battery cell 2 battery case 3 lid 4 external terminal 5 battery center 10 battery module 20 spacer 22 inter-battery spacer 24 end spacer 26 upper edge 27 center 28 bottom edge.

Claims (1)

a plurality of battery cells stacked in a stacking direction;
a spacer provided between the two battery cells adjacent in the stacking direction;
The battery cells viewed in the stacking direction have a rectangular shape,
The dimension in the long side direction of the battery cell in the plane perpendicular to the stacking direction is 1.5 times or more the dimension in the short side direction of the battery cell,
The thickness of the spacer gradually decreases from the first edge portion in the short side direction toward the center portion in the short side direction, gradually increases from the center portion toward the second edge portion in the short side direction, and reaches the second edge portion in the short side direction. The battery module, wherein the thickness at one edge is 1.3 times or more the thickness at the central portion, and the thickness at the second edge is 1.3 times or more the thickness at the central portion.

Images