Power storage device including cooling member with bulging portion caused by evaporation of coolant

A power storage module includes: a plurality of power storage elements; a plurality of cooling members each of which 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 at an extension portion extending in a region not overlapping the power storage element; and a heat transfer member that has a spacer portion disposed between the adjacent extension portions of the plurality of cooling members and configured to abut with the bulging portion.

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 is 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 plurality of power storage elements; a plurality of cooling members each of which has a coolant and a sealing body hermetically sealing the coolant, is stacked on the power storage elements, and is configured to form a bulging portion by deformation of the sealing body caused by evaporation of the coolant at an extension portion extending in a region not overlapping the power storage element; and a heat transfer member that has a spacer portion disposed between the adjacent extension portions of the plurality of cooling members and configured to abut with the bulging portion.

According to the foregoing configuration, it is possible to dissipate heat from the power storage elements via the cooling members in which the coolant is sealed in the sealing body and the heat transfer member. Accordingly, as compared to the configuration in which the coolant is charged in a case where the power storage elements are 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. When the bulging portion formed by the bulging and deformation of the sealing body in the cooling member is disposed in a space with low heat conductivity (air), there is caused a problem of poor heat dissipation property of the bulging portion.

According to the present configuration, the spacer portion disposed between the adjacent extension portions of the plurality of cooling members abuts with the bulging portion, and thus the heat of the power storage elements is transmitted from the cooling members to the heat transfer member to allow heat dissipation to the outside via the heat transfer member, thereby achieving improvement in heat dissipation property.

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

The heat transfer member may have a plurality of the spacer portions aligned, and the bulging portion may be disposed between the adjacent spacer portions.

Accordingly, the bulging portion easily adheres to the spacer portions, thereby to improve heat conductivity between the cooling member and the heat transfer member.

Out of the plurality of spacer portions, the spacer portions at ends in an alignment direction may have overhanging portions hanging over outward on outer surfaces thereof.

This allows heat dissipation via the overhanging portions of the heat transfer member, thereby to improve heat dissipation property.

The heat transfer member may include a coupling portion that couples the plurality of spacer portions, and a surface of the coupling portion may contact a surface of an external heat dissipation member.

Accordingly, it is possible to improve heat conductivity from the heat transfer member to the heat dissipation member, thereby to improve heat dissipation property.

The power storage module may further include a heat equalization plate that is stacked on the power storage element with the cooling member therebetween. The heat equalization plate may include a heat equalization extension portion that is extended to the heat transfer member side in the region not overlapping the power storage element.

Accordingly, the heat conductivity to the heat transfer member can be improved by the heat equalization extension portion of the heat equalization plate.

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 9. 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 Z direction is an upward direction.

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; a plurality of (six in the present embodiment) heat equalization plates30that are stacked between the cooling members20and the power storage elements11to receive heat of the cooling members20and the power storage elements11; and a heat transfer member40that is disposed between the cooling members20and an external heat dissipation member50to relay the heat of the cooling members20to the external heat dissipation member50.

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 together 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. 6. 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 equalization plate30. The cooling member20has an extension portion20A extended to a region not overlapping the power storage element11. The first sheet portion26A in the extension portion20A is set as a bulging portion28that is configured to bulge and deform by evaporation of the coolant21in the sealing body25as illustrated inFIG. 5. The bulging portion28is formed by bulging and deformation of the sealing body25with a rise in the inner pressure caused by evaporation of the coolant21at the extension portion20A of the cooling member20. 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 of the sealing body25is sandwiched between the power storage element11and the heat equalization plate30and is restricted in bulging.

Each of the heat equalization plates30is rectangular in shape and stacked on the power storage element11with the cooling member20therebetween and is formed from a member with high heat conductivity such as aluminum, aluminum alloy, copper, or copper alloy. Each of the heat equalization plates30has a contact portion31that contacts the power storage element11and the second sheet portion26B to receive heat of the power storage element11and a heat equalization extension portion32that extends in a region not overlapping the power storage element11on the right side of the contact portion31. In the present embodiment, there is formed a gap between a right end of the heat equalization extension portion32and a spacer portion41described later of the heat transfer member40on the right side. However, the present embodiment is not limited to this configuration, and the end of the heat equalization extension portion32and the heat transfer member40may be in contact with each other.

The heat transfer member40is formed from a metal with high heat conductivity such as aluminum, aluminum alloy, copper, or copper alloy and is formed to be longer than the length of the cooling member20in a front-back direction. As illustrated inFIGS. 8 and 9, the heat transfer member40includes a plurality of (six in the present embodiment) spacer portions41aligned in one line, a plurality of (five in the present embodiment) coupling portions42that couple the adjacent spacer portions41, and a pair of overhanging portions43that hangs over from outer surfaces of the spacer portions41at ends in an alignment direction. Each of the spacer portions41has a substantially U shape, has a length to be in abutment with the entire cooling member20in the front-back direction, and includes a pair of side wall portions41A and41B in parallel, and a front end wall41C that connects between the pair of side wall portions41A and41B. As illustrated inFIGS. 5 and 6, the heat transfer member40has the spacer portions41disposed between the plurality of adjacent extension portions20A of the plurality of cooling members20. The one side wall portion41A of the spacer portion41is in abutment with the second sheet portion26B. When the first sheet portion26A bulges and deforms by evaporation of the coolant21to form the bulging portion28, the bulging portion28deforms and adheres closely to the side wall portion41B and the coupling portion42.

The heat dissipation member50is disposed on a lateral side of the power storage module10to dissipate heat having been transferred to the heat equalization plates30to the outside. The heat dissipation member50is 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 member50may 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, and may be a liquid such as oil. Alternatively, the cooling liquid may be an antifreeze liquid. In addition, the cooling material is not limited to a liquid, and may be a gas.

The present embodiment produces the following operations and advantageous effects.

The power storage module10includes: the plurality of power storage elements11; the plurality of cooling members20each of which 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 coolant21at the extension portion20A extending in the region not overlapping the power storage element11; and the heat transfer member40that has the spacer portion41disposed between the adjacent extension portions20A of the plurality of cooling members20and configured to abut with the bulging portion28.

According to the present embodiment, it is possible to dissipate heat from the power storage elements11via the cooling members20in which the coolant21is sealed in the sealing body25and the heat transfer member40. Accordingly, as compared to the configuration in which the coolant21is charged in a case where the power storage elements11are 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. When the bulging portion28formed by the bulging and deformation of the sealing body25in the cooling member20is disposed in a space with low heat conductivity (air), there is caused a problem of poor heat dissipation property of the bulging portion28.

In addition, according to the present embodiment, the spacer portion41disposed between the adjacent extension portions20A of the plurality of cooling members20abuts with the bulging portion28, and thus the heat of the power storage elements11is transmitted from the cooling members20to the heat transfer member40to allow heat dissipation to the outside via the heat transfer member40, thereby achieving improvement in heat dissipation property.

The heat transfer member40has the plurality of spacer portions41aligned, and the bulging portion28is disposed between the adjacent spacer portions41.

Accordingly, the bulging portion28easily adheres to the spacer portions41, thereby to improve heat conductivity between the cooling member20and the heat transfer member40.

Out of the plurality of spacer portions41, the spacer portions41at ends in the alignment direction have the overhanging portions43hanging over outward on outer surfaces thereof.

This allows heat dissipation via the overhanging portions43of the heat transfer member40, thereby to improve heat dissipation property.

The heat transfer member40includes the coupling portion42that couples the plurality of spacer portions41, and surface of the coupling portion42contacts a surface of the external heat dissipation member50.

Accordingly, it is possible to improve heat conductivity from the heat transfer member40to the heat dissipation member, thereby to improve heat dissipation property.

The power storage module10further includes the heat equalization plate30that is stacked on the power storage element11with the cooling member20therebetween. The heat equalization plate30includes the heat equalization extension portion32that is extended to the heat transfer member40side in the region not overlapping the power storage element11but overlapping the cooling member20.

Accordingly, the heat conductivity to the heat transfer member40can be improved by the heat equalization extension portion32of the heat equalization plate30.

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 heat transfer member40includes the overhanging portions43. However, the heat transfer member40may not include the overhanging portions43.

(2) The bulging portion28is configured to contact (closely adheres to) substantially the entire side wall portion41A and the left surface of the main body21. However, the bulging portion28is not limited to this. At least part of the bulging portion28may be configured to abut with at least one of the side wall portion41A and the main body21.

(3) The bulging portion28is formed at the first sheet portion26A. Alternatively, the bulging portion28may be formed at both the first sheet portion26A and the second sheet portion26B. In this case, the bulging portions28may be in abutment with both the side wall portions41A and41B of the spacer portion41.

(4) The numbers of the power storage elements11, the cooling members20, and the heat equalization plates30are not limited to the numbers in the foregoing embodiments, and can be changed as appropriate. The numbers of the spacer portions41and the coupling portions42of the heat transfer member40can also be changed as appropriate according to the number of the cooling members20or the like.

(5) The power storage module10may not include the heat dissipation member50. 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 member50. In addition, the case may be a part of the heat dissipation member50, or the case may cover the entire power storage module10including the heat dissipation member50, 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.

EXPLANATION OF SYMBOLS