JP6987720B2 - Rechargeable battery pack - Google Patents

Description

The present invention relates to a secondary battery pack.

Currently, there is a high demand for in-vehicle secondary battery packs for the realization of a low-carbon society. A typical secondary battery is a lithium ion battery. Lithium-ion batteries are promising because they can be made smaller and have higher energy density than lead-acid batteries and nickel-metal hydride batteries. Here, the lithium ion battery generates heat during charging and discharging, and the internal temperature rises. Excessive temperature rise deteriorates the characteristics of the lithium-ion battery, so appropriate temperature control is required. In Patent Document 1 (Japanese Unexamined Patent Publication No. 2014-110218), in order to reduce the temperature difference between the secondary batteries, "a plurality of secondary batteries arranged side by side, a heat radiating portion facing the radiator, and a plurality of two batteries are provided. A battery module comprising a plurality of heat transfer plates having an inter-battery portion provided between the secondary batteries and a plurality of connecting members for connecting the terminals of the secondary batteries, wherein the batteries of the plurality of heat transfer plates are provided. The inter-battery absorbs the heat of the secondary battery, and the lengths of the plurality of secondary batteries in the juxtaposed direction are the same. A battery module including heat transfer plates having different heat dissipation efficiencies in the heat radiation unit is disclosed as a plurality of heat transfer plates.

In recent years, with the miniaturization of vehicles, secondary battery packs for automobiles are required to be further miniaturized, and at the same time, reduction of temperature variation in the secondary battery pack is also required. There is.

Japanese Unexamined Patent Publication No. 2014-11218

An object of the present invention is to reduce the temperature variation of the secondary battery while suppressing the increase in size of the apparatus.

The secondary battery pack of the present invention has a secondary battery laminate in which a plurality of secondary batteries are laminated, a plate portion arranged on the side of the secondary battery laminate, and a heat transfer member facing the secondary battery laminate. The plate portion is composed of a heat transfer region and a heat insulating region having a lower heat conductivity than the heat transfer region, and the heat transfer region is divided into a plurality of regions by the heat transfer region to dissipate heat. The member is in contact with the first heat transfer region including the central portion of the plate portion.

According to the present invention, it is possible to reduce the variation in the temperature of the secondary battery while suppressing the increase in size of the apparatus.

Perspective view showing the proposed structure of the secondary battery pack in Example 1 of the present invention. Schematic diagram showing the proposed structure of the secondary battery pack according to the first embodiment of the present invention. Schematic cross-sectional view showing the proposed structure of the plate portion in Example 1 of the present invention. Schematic cross-sectional view showing the conventional structure of the plate portion in Example 1 of the present invention. Schematic cross-sectional view showing the proposed structure of the plate portion in Example 2 of the present invention. Schematic diagram showing the proposed structure of the secondary battery pack according to the third embodiment of the present invention. Schematic cross-sectional view showing the proposed structure of the first plate portion and the second plate portion in Example 3 of the present invention. Perspective sectional view showing the proposed structure of the secondary battery pack in the implementation house 4 of the present invention. Schematic diagram showing the proposed structure of the secondary battery pack according to the fourth embodiment of the present invention. Schematic cross-sectional view showing the proposed structure of the secondary battery pack according to the fourth embodiment of the present invention. Results of steady-state heat transfer analysis of the proposed structure and conventional structure of the secondary battery pack in Example 4 of the present invention.

Detailed problems related to the principle of the secondary battery pack according to the present embodiment will be described. In recent years, there has been a demand for higher output of secondary battery packs, and it is necessary to mount many secondary batteries in the secondary battery pack. In order to meet the demand for miniaturization, a plurality of secondary batteries in the secondary battery pack are densely stacked, and as a result, the temperature varies depending on the stacked positions between the secondary batteries. It is known that if the temperature varies between the secondary batteries, the deterioration progresses quickly in the secondary battery with a high temperature, and in order to realize a secondary battery pack with a long life and high reliability, it is known. The challenge is to reduce the temperature variation between the secondary batteries.

An embodiment of the secondary battery pack according to the first embodiment of the present invention will be described. It should be noted that the following embodiment is an embodiment of the present invention and does not limit the present invention to the scope thereof.

FIG. 1 is a perspective view showing a proposed structure of a secondary battery pack according to the first embodiment of the present invention. FIG. 2 is a schematic diagram showing a proposed structure of the secondary battery pack according to the first embodiment of the present invention. FIG. 3 is a schematic cross-sectional view showing the proposed structure of the plate portion according to the first embodiment of the present invention.

The secondary battery assembly 101 is composed of a secondary battery laminate 102 and a plate portion 105. The secondary battery laminate 102 is configured by stacking a plurality of secondary batteries 1 so as to face the wide surface (xz surface). The plate portion 105 contacts the narrow surface (xy surface) of the secondary battery 1 constituting the secondary battery laminate 102 to form a heat transfer path. Further, the plate portion 105 is composed of a heat transfer region 2, a heat transfer region 3, a heat transfer region 4, a heat insulating region 5 that thermally separates them, and a heat insulating region 6. The heat transfer member 7 is in contact with the heat transfer region 3 at the center of the plate portion 105. Further, the heat transfer member 7 is cooled (not shown).

FIG. 4 is a schematic cross-sectional view showing the conventional structure of the plate portion according to the first embodiment of the present invention. In contrast to the proposed structure shown in FIG. 3, the conventional structure of FIG. 4 does not have a heat insulating region, the plate portion 105 is composed of only the heat transfer region 2, and the cooling effect acting on the heat transfer member 7 is the plate portion. The temperature of the whole 105 is lowered. At this time, since the plate portion 105 is made of a material having high thermal conductivity, it comes into contact with the secondary battery laminate 102 in a state where the internal temperature is close to uniform. However, in the secondary battery laminate 102, the heat conductivity in the stacking direction (y direction) becomes small due to the influence of the winding group inside the secondary battery 1, so that the temperature inside the heat transfer region 2 is uniform. However, a temperature difference occurs in the secondary battery laminate 102 in the stacking direction (y direction) of the secondary battery 1.

On the other hand, by adopting the proposed structure shown in FIG. 3, the cooling effect exerted on the heat transfer member 7 is close to the central region where the heat of the secondary battery laminate 102 is concentrated and the temperature tends to rise. It shows the function of intensively removing heat from the heat transfer region 3. As a result, the temperature of the heat transfer region 3 at the center of the plate portion 105 is lower than the temperatures of the heat transfer regions 2 and the heat transfer regions 4 at the ends, and the stacking direction (y direction) of the secondary battery laminate 102 is formed. ) Excessive temperature rise in the secondary battery 1 in the central portion is suppressed, and the temperature variation between the secondary batteries 1 is reduced. At this time, since it is possible to implement the proposed embodiment by converting a part of the plate portion 105 in the conventional structure into a heat insulating region, the size of the secondary battery assembly 101 does not increase, and the size of the secondary battery assembly 101 does not increase. It is not necessary to prepare different parts for each next battery 1. According to the above embodiment, it is possible to provide a secondary battery pack in which the temperature variation between secondary batteries is reduced without causing an increase in dimensions and an increase in the number of parts and types.

It is desirable that the heat transfer region 2, the heat transfer region 3, and the heat transfer region 4 are made of a material having high thermal conductivity from the viewpoint of cooling. Further, from the viewpoint of lashing the secondary battery laminate 102, it is desirable that the secondary battery laminate 102 is made of a material having a high Young's modulus. Further, from the viewpoint of weight, it is desirable that the material is composed of a material having a low density. For example, it is desirable that it is composed of a material such as aluminum or an aluminum alloy. The heat transfer region may be two or more, and is not limited to the embodiment of the present embodiment.

The heat insulating region 5 and the heat insulating region 6 provide a temperature difference between the heat transfer regions that are separated by increasing the thermal resistance of the region. For this purpose, there is a means for mainly forming a material having a thermal conductivity smaller than that of the heat transfer region in the region. For example, it is conceivable to use a resin material, a rubber material, an air layer, an airgel material, a porous material, or the like. In addition, there is a means for forming the region with a cross-sectional area smaller than that of the heat transfer region. For example, it is conceivable to provide an opening or a throttle.

It is desirable that the heat transfer path between the secondary battery laminate 102 and the plate portion 105 has a small thermal resistance. For that purpose, for example, a method of applying a heat conductive grease, a heat conductive adhesive, or the like to a contact portion between the secondary battery laminate 102 and the plate portion 105, or providing a heat conductive sheet to utilize the heat conductive material. Alternatively, a method of pressing and fixing the secondary battery laminate 102 and the plate portion 105 can be considered.

Similar to the heat transfer region, the heat transfer member 7 is preferably made of a material having high thermal conductivity from the viewpoint of cooling. Further, from the viewpoint of weight, it is desirable that the material is composed of a material having a low density. For example, it is desirable that it is composed of a material such as aluminum or an aluminum alloy.

It is desirable that the heat transfer path between the plate portion 105 and the heat transfer member 7 has a small thermal resistance. For that purpose, for example, a heat conductive material such as a heat conductive grease or a heat transfer adhesive may be applied to the contact portion between the plate portion 105 and the heat transfer member 7, or a heat transfer sheet may be provided to utilize the heat transfer material. A method of pressing the plate portion 105 and the heat transfer member 7 to fix the heat transfer member 7 can be considered. Further, by applying cooling means such as air cooling, liquid cooling, and electronic cooling to the heat transfer member 7, it is possible to suppress the temperature rise of the secondary battery.

A form of the secondary battery pack according to the second embodiment of the present invention will be described. It should be noted that the following embodiment is an embodiment of the present invention and does not limit the present invention to the scope thereof.

FIG. 5 is a schematic cross-sectional view showing the proposed structure of the plate portion in the second embodiment of the present invention. The direction of the heat insulating region is not limited to the xz plane direction. For example, as shown in the heat insulating region 5 in the figure, the plate portion 105 can be separated into the heat transfer region 2 and the heat transfer region 3 by a structure in which the xz plane direction and the yz plane direction are combined.

For example, the secondary battery laminate 102 has a structure in which the surface on the small side in the x direction is cooled from the surface on the small side in the x direction, and the surface on the small side in the x direction is low temperature and the surface on the large side in the x direction is high temperature in the secondary battery 1. Consider the case where the temperature varies so as to become. At this time, the heat of the secondary battery laminate 102 tends to concentrate in the center of the y direction and the temperature tends to rise, and the heat tends to concentrate on the larger side in the x direction and the temperature tends to rise. Therefore, by thermally connecting the heat transfer region 3 and the heat transfer member 7, the temperature variation in the stacking direction (y direction) of the secondary battery 1 can be reduced, and the position is located at the center of the secondary battery stack 102. Inside the secondary battery 1, the effect of reducing the temperature variation in the depth direction (x direction) can be expected.

An embodiment of the secondary battery pack according to the third embodiment of the present invention will be described. It should be noted that the following embodiment is an embodiment of the present invention and does not limit the present invention to the scope thereof.

FIG. 6 is a schematic diagram showing a proposed structure of the secondary battery pack according to the third embodiment of the present invention. The secondary battery assembly shown in the figure has a secondary battery laminate 103 and a secondary battery laminate 104, a first plate portion 106 between them, and a secondary battery laminate 103 together with the first plate portion 106. It has a second plate portion 107 and a first plate portion 106 that sandwich the secondary battery laminate 103, and a third plate portion 108 that sandwiches the secondary battery laminate 103.

FIG. 7 is a schematic cross-sectional view showing the proposed structure of the first plate portion and the second plate portion in the third embodiment of the present invention. The first plate portion 106 is separated into three heat transfer regions by two heat insulating regions, and is close to a region where the heat of the secondary battery laminate 103 and the secondary battery laminate 104 is concentrated and the temperature tends to rise. The heat transfer region 8 in the central portion is formed with the heat transfer member 7 and the heat transfer path. The second plate portion 107 is separated into three heat transfer regions by two heat insulating regions, and the heat transfer region in the central portion close to the region where the heat of the secondary battery laminate 103 tends to concentrate and the temperature rises. 9 forms a heat transfer path with the heat transfer member 7. Similarly, the third plate portion 108 is separated into three heat transfer regions by two heat insulating regions, and is located in the central portion close to the region where the heat of the secondary battery laminate 104 is concentrated and the temperature tends to rise. The heat transfer region 10 forms a heat transfer path with the heat transfer member 7 (not shown).

When the two secondary battery laminates are adjacent to each other via the plate portion as described above, in the secondary battery laminate 103 and the secondary battery laminate 104, the secondary battery in the center of the stacking direction (y direction) As the temperature of 1 becomes higher than that of the other secondary batteries 1, a high temperature region appears in a region close to the first plate portion 106 in one secondary battery 1.

Therefore, in this embodiment, the contact area between the heat transfer region 8 of the first plate portion 106 and the secondary battery laminate 103, where heat is concentrated and the temperature is likely to rise, and the second, where heat is concentrated and the temperature is likely to rise. The contact area between the heat transfer region 8 of the one plate portion 106 and the secondary battery laminate 104 is the contact area between the heat transfer region 9 of the second plate portion 107 and the secondary battery laminate 103, and the contact area of the third plate portion 108. The structure is larger than the contact area between the heat transfer region 10 and the secondary battery laminate 104. As a result, the amount of heat transfer from the heat transfer region 8 to the heat transfer member 7 is larger than the amount of heat transfer from the heat transfer region 9 to the heat transfer member 7 and the amount of heat transfer from the heat transfer region 10 to the heat transfer member 7. Become. Therefore, it is possible to reduce the variation in the temperature of the secondary battery 1 in the stacking direction (y direction), and inside the secondary battery 1 located at the center of each of the secondary battery laminate 103 and the secondary battery laminate 104. The effect of reducing the variation in temperature in the horizontal direction (z direction) can be expected.

Here, in this embodiment, the amount of heat resistance of the heat transfer path is increased by making a difference in the contact area between the heat transfer region close to the region where heat is concentrated and the temperature tends to rise and the secondary battery laminate. Although it has been changed, the same effect can be expected by using other heat conductive materials with different thermal conductivity and thickness, or by taking measures such as providing openings and throttles to change the cross-sectional area. can.

Further, by fastening the heat transfer member 7, the first plate portion 106, the second plate portion 107, and the third plate portion 108, the secondary battery laminate is subjected to a compressive force in the horizontal direction (z direction). The effect of reducing the applied load can be obtained. Therefore, it is desirable that the heat transfer member 7 is made of a material having a large Young's modulus. Further, from the viewpoint of cooling, it is desirable that the material is made of a material having high thermal conductivity. Further, from the viewpoint of weight, it is desirable that the material is composed of a material having a low density. For example, it is desirable that it is composed of a material such as aluminum or an aluminum alloy.

An embodiment of the secondary battery pack according to the fourth embodiment of the present invention will be described. It should be noted that the following embodiment is an embodiment of the present invention and does not limit the present invention to the scope thereof.

FIG. 8 is a perspective sectional view showing a proposed structure of a secondary battery pack in the implementation hall 4 of the present invention. FIG. 9 is a schematic diagram showing the proposed structure of the secondary battery pack according to the fourth embodiment of the present invention. Further, FIG. 10 is a schematic cross-sectional view showing the proposed structure of the secondary battery pack according to the fourth embodiment of the present invention. In this embodiment, the main configurations of the secondary battery laminate 103, the secondary battery laminate 104, the first plate portion 106, the second plate portion 107, and the third plate portion 108 are the same as those in the third embodiment. The secondary battery assembly 101 has an end plate 11 for fixing the secondary battery laminate 103, the secondary battery laminate 104, the first plate portion 106, the second plate portion 107, and the third plate portion 108. The secondary battery pack 109 has a housing 12 that houses the secondary battery assembly 101, the heat transfer member 7, and the control unit 13.

The secondary battery laminate 103 and the secondary battery laminate 104 are each composed of 12 secondary batteries 1. The first plate portion 106 is located between the third secondary battery 1 and the fourth secondary battery 1 from the bottom and the position between the second secondary battery 1 and the third secondary battery 1 from the top. Separated by an insulating area. The second plate portion 107 and the third plate portion 108 are located between the fourth secondary battery 1 and the fifth secondary battery 1 from the bottom, and the second secondary battery 1 and the third secondary battery 1 from the top. It is separated by a heat insulating region at a position between the batteries 1.

The heat transfer member 7 is connected to a heat transfer region 8, a heat transfer region 9, and a heat transfer region 10 in the central portions of the first plate portion 106, the second plate portion 107, and the third plate portion 108, respectively. Further, the heat transfer member 7 projects outward from the left and right sides of the housing 12, and the projecting portion is water-cooled.

The end plate 11 firmly binds the secondary battery laminate 103, the secondary battery laminate 104, the first plate portion 106, the second plate portion 107, and the third plate portion 108 from above and below.

The secondary battery assembly 101 is in contact with the housing 12 on the bottom surface side of the can of the secondary battery 1 via a heat conductive material.

The outside of the housing 12 is an air environment, and the heat generated by the secondary battery assembly 101 is mainly the conduction heat transfer from the heat transfer member 7 that is water-cooled from the outside and the housing 12 that hits the bottom side of the can of the secondary battery 1. Cooled by natural convection heat transfer from the back of the.

In order to verify the effect of reducing the temperature variation of the embodiment of this embodiment, a three-dimensional steady thermo-fluid analysis was performed on the embodiment of this embodiment and the conventional structure, and the temperature distribution of the secondary battery 1 was compared. Here, in this embodiment, there is no heat insulating region in the first plate portion 106, the second plate portion 107, and the third plate portion 108, and each of them is one as shown in FIG. 4 in a schematic cross-sectional view thereof. The form composed of the heat transfer region is positioned as the conventional structure. Other analysis conditions were the same for both the proposed structure and the conventional structure.

FIG. 11 shows the results of steady heat transfer analysis of the proposed structure and the conventional structure of the secondary battery pack in Example 4 of the present invention. The curve of FIG. 11 shows the temperature distribution on the vertical line passing through the highest temperature point in the secondary battery assembly of FIG. The vertical axis of FIG. 11 is the temperature, and the horizontal axis is the distance from the lower surface of the lowermost secondary battery 1 to the upper surface of the uppermost secondary battery 1. The solid black line and the broken gray line show the results of heat transfer analysis of the conventional structure and the proposed structure, respectively.

In the analysis result of the temperature distribution shown in FIG. 11, when the difference between the maximum temperature and the minimum temperature was obtained, it was 5.2 degrees and 4.4 degrees for the conventional structure and the proposed structure, respectively. From this, it was found that the effect of reducing the temperature variation between the secondary batteries 1 by about 15% can be obtained by changing from the conventional structure to the proposed structure. At this time, the maximum temperatures were 51.2 degrees and 51.3 degrees, respectively, in the conventional structure and the proposed structure. From this, it was found that the maximum temperature of the secondary battery 1 does not rise significantly even with the proposed structure from the conventional structure.

As described above, the above-mentioned form reduces the temperature variation between the secondary batteries without causing an increase in dimensions, an increase in the number of parts and types, and without significantly increasing the maximum temperature of the secondary battery. It will be possible to provide the next battery pack.

1 ... Secondary battery 2 ... Heat transfer area 3 ... Heat transfer area 4 ... Heat transfer area 5 ... Insulation area 6 ... Insulation area 7 ... Heat transfer member 8 ... Heat transfer region 9 ... Heat transfer region 10 ... Heat transfer region 11 ... End plate 12 ... Housing 13 ... Control unit 101 ... Secondary battery assembly 102 ... Secondary Battery laminate 103 ... Secondary battery laminate 104 ... Secondary battery laminate 105 ... Plate portion 106 ... First plate portion 107 ... Second plate portion 108 ... Third plate Part 109 ・ ・ ・ Secondary battery pack

Claims (7)

A secondary battery laminate in which multiple secondary batteries are stacked, and
A plate portion you contact with the side of the secondary battery stack,
And a heat transfer member that faces the secondary battery stack,
The plate portion is composed of a heat transfer region and a heat insulating region having a lower thermal conductivity than the heat transfer region.
The heat transfer region is divided into a plurality of regions by the heat insulating region.
The heat transfer member, said plate portion first heat exchanger area in contact with the secondary battery pack is the heat transfer area of the center of. The secondary battery pack according to claim 1.
The heat insulating region is composed of a first heat insulating region and a second heat insulating region in contact with the first heat transfer region.
The plate portion has a second heat transfer region facing the first heat transfer region across the first heat insulation region and a third heat transfer region facing the first heat transfer region across the second heat transfer region. Area, and has a secondary battery pack. The secondary battery pack according to claim 1.
The heat insulating area is
The first insulation area and
A second heat insulating region facing the first heat insulating region across the center of the plate portion,
Ri connected to the person said first insulation region and the second insulation region, together with the first insulation region and the second insulation region, so separating the plate portion and the first heat exchanger area and a second heat exchanger region A secondary battery pack that has a third insulation area, which is placed in. The secondary battery pack according to any one of claims 1 to 3.
The plate portion is
The first plate portion arranged on one side of the secondary battery laminate and
A secondary battery pack composed of a second plate portion arranged on the other side opposite to the first plate portion with the secondary battery laminate interposed therebetween. The secondary battery pack according to claim 4.
The first of the secondary battery stack comprises a second of the secondary battery stack disposed on opposite sides of the said first plate portion,
The plate portion is
And the second of the said first plate portion across the secondary battery stack constituted by a third plate portion disposed on the opposite side,
If said first plate portion and the first of the secondary battery laminate viewed from the direction of stacking,
The first plate portion is a secondary battery pack in which the area of the first heat transfer region is larger than the area of the first heat transfer region in the other plate portion. The secondary battery pack according to any one of claims 1 to 5.
Includes an end plate for lashing and said secondary battery stack and the plate portion so as to sandwich the laminating direction of the secondary battery stack,
The end plate is a secondary battery pack that is in contact with a heat transfer region of the plate portion other than the first heat transfer region. The secondary battery pack according to any one of claims 1 to 6.
A housing for accommodating the secondary battery laminate, the plate portion, and the heat transfer member is provided.
The housing is a secondary battery pack for connecting the plate portion on a surface facing the surface where the plate portion contacts the heat transfer member .

Images