Power storage module

A power storage module includes: a power storage element; a cooling member that has a coolant and a sealing body hermetically sealing the coolant, is stacked on the power storage element, and is configured to form a bulging portion by deformation of the sealing body caused by evaporation of the coolant in a region not overlapping the power storage element; a heat transfer plate that is stacked on the power storage element with the cooling member sandwiched therebetween; and an elastic member that abuts with the heat transfer plate and the bulging portion and is elastically deformable.

TECHNICAL FIELD

The present description discloses a technique for dissipating heat from a power storage element.

BACKGROUND ART

There has been conventionally known a technique for dissipating heat from a power storage element. Patent Document 1 describes that a battery module is stored in a pack case and positive terminals and negative terminals of a plurality of cells are electrically connected together via bus bars. When a coolant charged in the lower portion of the pack case becomes evaporated and condensed in the upper portion of the pack case, heat of the battery is dissipated to the outside.

RELATED ART DOCUMENT

Patent Document

DISCLOSURE OF THE PRESENT INVENTION

Problem to be Solved by the Invention

According to the technique described in Patent Document 1, the coolant needs to be evaporated and condensed in the pack case, and thus the entire pack case needs to be sealed. This causes a problem that it is not easy to simplify the configuration of the power storage module.

The technique disclosed herein is completed under the foregoing circumstances, and an object of the technique is to simplify the configuration of the power storage module.

Means for Solving the Problem

A power storage module described herein includes: a power storage element; a cooling member that has a coolant and a sealing body hermetically sealing the coolant, is stacked on the power storage element, and is configured to form a bulging portion by deformation of the sealing body caused by evaporation of the coolant in a region not overlapping the power storage element; a heat transfer plate that is stacked on the power storage element with the cooling member therebetween; and an elastic member that abuts with the heat transfer plate and the bulging portion and is elastically deformable.

According to the foregoing configuration, it is possible to dissipate heat from the power storage element via the cooling member in which the coolant is sealed in the sealing body and the heat transfer plate. Accordingly, as compared to the configuration in which the coolant is charged in a case where the power storage element is stored, for example, the case does not necessarily need to be sealed. This makes it possible to simplify the configuration of the power storage module. In the case of using the cooling member and the heat transfer plate for dissipating heat from the power storage element, when the bulging portion formed by the bulging and deformation of the sealing body is not in contact with the heat transfer plate, the heat of the bulging portion is dissipated via a space with low heat conductivity (air). This causes a problem of poor heat dissipation property of the bulging portion. According to the present configuration, when the elastic member abuts with the heat transfer plate and the bulging portion, the heat of the bulging portion is transferred to the heat transfer plate via the elastic member to allow heat dissipation to the outside via the heat transfer plate, thereby to improve heat dissipation property. In addition, the elastic member is elastically deformed according to the bulging of the bulging portion, so that it is possible to lengthen the time during which the elastic member is in contact with the bulging portion to improve thermal conductivity.

Embodiments of the technique described herein are preferably as described below.

The elastic member may be a sponge, and an outer surface of the sponge may contact a surface of the heat transfer plate.

The elastic member may be a spring, and an end portion of the spring may be fixed to at least one of the heat transfer plate and the bulging portion.

The heat transfer plate may have a partition wall that extends in a direction different from a surface on which the power storage element is stacked and separates the elastic member such that the partition wall and the elastic member abut with each other.

This makes it possible to transfer the heat of the bulging portion to the partition wall via the elastic member to improve heat dissipation property.

The power storage module may include a plurality of the cooling members, a plurality of the power storage elements, and a plurality of the heat transfer plates. The elastic member may be sandwiched between the heat transfer plates and the bulging portions.

Accordingly, it is possible to improve heat conductivity among the bulging portions, the heat transfer plates, and the elastic members.

The cooling member may include an absorption member that is disposed in the sealing body to absorb the coolant.

This makes the coolant easy to move by the absorption member, which makes it possible to improve the cooling performance of the cooling member.

Advantageous Effect of the Invention

According to the technique described herein, it is possible to simplify the configuration of the power storage module.

MODES FOR CARRYING OUT THE INVENTION

First Embodiment

A first embodiment will be described with reference toFIGS. 1 to 7. A power storage module10in the present embodiment is mounted in a vehicle such as an electric car or a hybrid car, for example, to supply electric power to a load such as a motor. Although the power storage module10can be disposed in any orientation, the following descriptions are based on the assumption that an X direction is a leftward direction, a Y direction is a forward direction, and a direction is an upward direction.

Power Storage Module10

As illustrated inFIG. 4, the power storage module10includes: a plurality of (six in the present embodiment) power storage elements11; a plurality of (six in the present embodiment) cooling members20that are stacked on the power storage elements11to cool the power storage elements11; plurality of (six in the present embodiment) heat transfer plates30that are stacked between the cooling members20and the power storage elements11to transmit heat from the cooling members20and the power storage elements11; and elastic members39(six in the present embodiment) that contact the heat transfer plates30and the cooling members20and are elastically deformable.

Power Storage Elements11

Each of the power storage elements11is formed by sandwiching a power storage factor not illustrated between a pair of battery laminate sheets and bonding side edges of the battery laminate sheets in a liquid-tight manner by a publicly known method such as heat welding. A positive electrode terminal12A and a negative electrode terminal12B in metallic foil form protrude from the front end edge of each of the power storage elements11, from inside to outside of the battery laminate sheets in a liquid-tight state with the inner surface of the battery laminate sheet as illustrated inFIG. 1. The electrode terminal12A and the electrode terminal12B of each of the power storage elements11are disposed with a space therebetween and are electrically connected to the internal power storage factor.

The plurality of power storage elements11are vertically aligned and the adjacent power storage elements11are disposed such that one electrode terminal12A is positioned next to the other electrode terminal12B. The adjacent electrode terminal12A and electrode terminal12B are electrically connected together via a plurality of (five in the present embodiment) U-shaped connection members13. The electrode terminals12A,12B and the connection members13are connected together by a publicly known method such as laser welding, ultrasonic welding, or brazing, for example. The adjacent electrode terminals12A and12B are connected by the connection members13, so that the plurality of power storage elements11are connected in series.

In the present embodiment, examples of the power storage elements11include secondary batteries such as lithium-ion secondary batteries or nickel-metal-hydride secondary batteries, capacitors such as electric double-layer capacitors or lithium ion capacitors, and any type can be selected as necessary.

Each of the cooling members20includes a coolant21that varies between liquid and gaseous states, an absorption member22that absorbs the coolant21, and a sealing body25that hermetically seals the coolant21and the absorption member22, as illustrated inFIG. 4. The coolant21can be one or more selected from a group consisting of perfluorocarbon, hydrofluoroether, hydrofluoroketone, fluorine inert liquid, water, and alcohols such as methanol and ethanol, for example. The coolant21may have insulating properties or conductive properties. The amount of the coolant21sealed in the sealing body25can be selected as necessary.

The absorption member22has a substantially rectangular sheet shape. The absorption member22is formed from a material that can absorb the coolant21. The absorption member22may be formed by processing a material configured to absorb the coolant21in fiber form and weaving into a fabric or may be formed from a non-woven fabric. The form of the non-woven fabric may be fiber sheet, web (thin film sheet made of fiber only), or bat (blanket-like fiber). The material for the absorption member22may be natural fiber, synthetic fiber formed from synthetic resin, or a combination of natural fiber and synthetic fiber.

The absorption member22is disposed in a wide region as compared to the region overlapping the power storage element11, and thus the absorption member22in the sealing body25includes an absorption extension portion23that is extended from the region overlapping the power storage element11to a region not overlapping the power storage element11.

The sealing body25can be formed by bonding together two substantially rectangular sheet members in a liquid-tight manner by a publicly known method such as adhesion, welding, or deposition, for example. Each of the sheet members is formed by laminating a synthetic resin film to the both sides of a metallic sheet. The metal constituting the metallic sheet can be any metal selected from among aluminum, aluminum alloy, copper, and copper alloy as necessary. The synthetic resin constituting a synthetic resin film can be any synthetic resin selected from among polyolefins such as polyethylene and polypropylene, polyesters such as polybutylene terephthalate and polyethylene terephthalate, polyamides such as nylon 6 and nylon 6, 6 as necessary. The sealing body25according to the present embodiment is formed by stacking and thermally fusing the surfaces of two sheet members with synthetic resin films.

The sealing body25has a first sheet portion26A to cover the upper side of the absorption member22and a second sheet portion26B to cover the lower side of the absorption member22as illustrated inFIG. 6. The upper surface of the first sheet portion26A is in contact with the lower surface of the power storage element11and the lower surface of the second sheet portion26B is in contact with the upper surface of the heat transfer plate30. A portion of the first sheet portion26A extended to a region not overlapping the power storage element11and covering the absorption extension portion23of the absorption member22is set as a bulging portion28that is deformable by evaporation of the coolant21in the sealing body25.

The bulging portion28is formed when the sealing body25becomes deformed and bulged with a rise in the inner pressure of the sealing body25caused by evaporation of the coolant21in the sealing body25. The portion of the sealing body25other than the bulging portion28does not bulge or deform even with a rise in the inner pressure caused by evaporation of the coolant21in the sealing body25because the portion is in contact with the power storage element11and the heat transfer plate30and is restricted in bulging.

Heat Transfer Plates30

Each of the heat transfer plates30has a rectangular shape and stacked on the power storage element11with the cooling member20therebetween and is formed from a member with high thermal conductivity such as aluminum, aluminum alloy, copper, or copper alloy. Each of the heat transfer plates30includes: a flat plate-shaped contact portion31that is in contact with the power storage element11and the second sheet portion26B; a heat transfer extension portion36that extends flush with the contact portion31on the right side of the contact portion31; a partition wall37that extends from an end edge of the heat transfer extension portion36in a direction orthogonal to the plate surface of the heat transfer extension portion36. The contact portion31has a rectangular shape and is stacked on a region of the power storage element11to receive heat from the power storage element11. The partition wall37has a size (height) to contact the entire right side surfaces of the elastic member39and the bulging portion28, and the outer surface of the partition wall37is in surface contact with the left side surface of a heat dissipation member40.

Each of the elastic members39is an elastically deformable sponge, for example, that is made of a porous synthetic resin, has a rectangular cross section, and extends in a belt shape in a front-back direction. As illustrated inFIG. 6, an upper surface39A of the elastic member39is in surface contact with a lower surface of the heat transfer extension portion36of the heat transfer plate30on the upper-stage side (adjacent), a right side surface29B of the elastic member39is in surface contact with a left surface of the partition wall37of the heat transfer plate30, and a lower surface39C of the elastic member39is in surface contact with an upper surface of the sealing body25(bulging portion28). The elastic member39is fixed to the lower surface of the heat transfer extension portion36and the upper surface of the sealing body25by an adhesive or the like, for example, but the elastic member39may not be fixed by an adhesive or the like. When the coolant21evaporates and the sealing body25bulges and deforms to form the bulging portion28, as illustrated inFIG. 5, the elastic member39elastically contracts and the coolant21becomes condensed and the bulging portion28contracts and returns to the original form, and then the elastic member39elastically bulges. Accordingly, the heat of the power storage elements11transfers to the heat transfer plates30vertically adjacent to each other with the cooling members20and the elastic members39therebetween and the heat dissipation member40, and then is dissipated from the heat dissipation member40to the outside.

The heat dissipation member40is disposed on a lateral side of the power storage module10to dissipate heat having been transferred to the heat transfer plates30to the outside. The left side surface (power storage module10side surface) of the heat dissipation member40closely adheres to the outer surfaces of the partition walls37of the heat transfer plates30. The heat dissipation member10is formed from a metal such as aluminum or aluminum alloy and has an inlet opening and an outlet opening for a cooling material not illustrated. A cooling liquid as a cooling material is introduced into the lower inlet opening and discharged from the upper outlet opening. The cooling liquid circulates through a heat dissipation path not illustrated to dissipate heat having been transferred to the cooling liquid to the outside. The heat dissipation member40may have a pipe (not illustrated) for passage of the cooling liquid entirely extending inside with a plurality of folds. In the present embodiment, the cooling liquid is water. However, the cooling liquid is not limited to this but may be a liquid such as oil. Alternatively, the cooling liquid may be an antifreeze liquid. In addition, the cooling liquid is not limited to a liquid but may be a gas.

The present embodiment produces the following operations and advantageous effects.

The power storage module10includes: the power storage element11; the cooling member20that has the coolant21and the sealing body25hermetically sealing the coolant21, is stacked on the power storage element11, and is configured to form the bulging portion28by deformation of the sealing body25caused by evaporation of the coolant21in a region not overlapping the power storage element11; the heat transfer plate30that is stacked on the power storage element11with the cooling member20sandwiched therebetween; and the elastic member39that abuts with the heat transfer plate30and the bulging portion28and is elastically deformable.

According to the present embodiment, it is possible to dissipate heat from the power storage element11via the cooling member20in which the coolant21is sealed in the sealing body25and the heat transfer plate30. Accordingly, as compared to the configuration in which the coolant21is charged in the case where the power storage element11is stored, for example, the case does not necessarily need to be sealed. This makes it possible to simplify the configuration of the power storage module10. In the case of using the cooling member20and the heat transfer plate30for dissipating heat from the power storage element11, when the bulging portion28formed by the bulging and deformation of the sealing body25is not in contact with the heat transfer plate30, the heat of the bulging portion28is dissipated via a space with low heat conductivity (air), which causes a problem of poor dissipation of heat from the bulging portion28. According to the present embodiment, when the elastic member39abuts with the heat transfer plate30and the bulging portion28, the heat of the bulging portion28is transferred to the heat transfer plate30via the elastic member39to allow heat dissipation to the outside via the heat transfer plate30, thereby to improve heat dissipation property. In addition, the elastic member39is elastically deformed according to the bulging of the bulging portion28, so that it is possible to lengthen the time during which the elastic member39is in contact with the bulging portion28to improve heat conductivity.

The elastic member39is a sponge, and an upper surface39A (outer surface) and a side surface39B (outer surface) of the sponge contact surfaces of the heat transfer plate30to enhance heat conductivity between the elastic member39and the heat transfer plate30.

The heat transfer plate30has the partition wall37that extends in a direction different from a surface on which the power storage element11is stacked and separates the elastic member39such that the partition wall37and the elastic member39abut with each other.

This makes it possible to transfer the heat of the bulging portion28to the partition wall37via the elastic member39to improve heat dissipation property.

The power storage module10includes the plurality of cooling members20, the plurality of power storage elements11, and the plurality of heat transfer plates30, and the elastic member39is sandwiched between the heat transfer plates30and the bulging portions28.

Accordingly, it is possible to improve heat conductivity among the bulging portions28, the heat transfer plates30, and the elastic members39.

The cooling member includes the absorption member22that is disposed in the sealing body25to absorb the coolant21.

Accordingly, the coolant21can be easily moved by the absorption member22, which makes it possible to improve the cooling performance of the cooling members20.

Second Embodiment

Next, a second embodiment will be described with reference toFIGS. 8 to 13. A power storage module50in the second embodiment has elastic members51as springs between heat transfer plates30and bulging portions28. Hereinafter, the identical components to those in the first embodiment will be given the identical reference signs to those in the first embodiment and descriptions thereof will be omitted.

As illustrated inFIG. 8, a plurality of (three for each cooling member in the present embodiment) elastic members51are fixed to each of the cooling members20with a space above the upper surface of the bulging portion28. Each of the elastic members39is a coil spring as illustrated inFIG. 13. This spring is made of a synthetic resin or a metal, for example. An end portion of the elastic member51is fixed to at least one of the heat transfer plate30and the bulging portion28. In the present embodiment, the end portion of the elastic member51is fixed to the bulging portion28by soldering or an adhesive, for example. Alternatively, the end portion of e elastic member51may be fixed to the heat transfer plate30or fixed to both the heat transfer plate30and the bulging portion28, for example.

According to the second embodiment, the bulging portion28and the heat transfer plate30on a stage different from the stage of the bulging portion28with the power storage element11sandwiched therebetween are coupled to each other by the elastic member39(FIG. 12). When the bulging portions28of the cooling members20bulge and deform (FIG. 11), the elastic members51elastically contract between the bulging portions28and the heat transfer extension portions36of the heat transfer plates30. When the bulging portions28no longer bulge or deform, the elastic members51extend to the original strength (FIG. 12).

Other Embodiments

The technique described herein is not limited to the embodiments described above and illustrated in the drawings. For example, the following embodiments are included in the scope of the technique described herein:

(1) The elastic members39,51are not limited to the sponges or springs in the foregoing embodiments. The elastic members are not limited to coil springs but may be plate springs or rubber other than springs, for example, as far as they are higher in thermal conductivity than air.

(2) The numbers of the power storage elements11, the cooling members20, the heat transfer plates30, and the elastic members39,51are not limited to the numbers in the foregoing embodiments but can be changed as appropriate.

(3) The heat dissipation member40may not be included. For example, the power storage module10may be covered with a metallic or synthetic resin case not illustrated, so that the heat of the power storage module10is dissipated via the case to the outside without the intervention of the heat dissipation member40. In addition, the case may be a part of the heat dissipation member40or the case may cover the entire power storage module10including the heat dissipation member40, for example. In this case, for example, the case may sandwich the power storage module10from the upper and lower sides to hold the power storage module10. The upper end of the elastic member39,51on the topmost stage is not fixed in the foregoing embodiment, but the upper end of the elastic member39,51on the topmost stage may be fixed. For example, the upper end of the elastic member39,51may be fixed by a case or the like not illustrated, so that the elastic members39,51can elastically deform.

EXPLANATION OF SYMBOLS