WO2020174804A1

WO2020174804A1 - Battery module

Info

Publication number: WO2020174804A1
Application number: PCT/JP2019/048021
Authority: WO
Inventors: 謙一今井; 貴大百田
Original assignee: 三洋電機株式会社
Priority date: 2019-02-27
Filing date: 2019-12-09
Publication date: 2020-09-03
Also published as: JP2022062288A

Abstract

In order to suppress a chain reaction of overheating while reducing variations in temperature distribution among a plurality of batteries, a battery module (1) is provided with: a plurality of batteries (14) that are stacked; a separator (16) that is disposed between two adjacent batteries (14), and provides electrical isolation between these two batteries (14), the separator (16) comprising a heat conduction suppression part (72) and a heat conduction acceleration part (74); and a cooling part (6) that is thermally connected to the plurality of batteries (14). The heat conduction suppression part (72) has lower heat conductivity than the heat conduction acceleration part (74), and suppresses heat conduction between the two adjacent batteries (14). The heat acceleration part (74) is in contact with the cooling part (6), accelerates heat conduction between the two adjacent batteries (14), and conducts the heat of the batteries (14) to the cooling part (6).

Description

Battery module

The present invention relates to a battery module.

For example, a battery module in which a plurality of batteries are electrically connected is known as a power source for vehicles, which requires a high output voltage. Regarding such a battery module, Patent Document 1 discloses a battery stack in which a plurality of batteries are stacked, a separator arranged between adjacent batteries, and metal ends arranged at both ends of the battery stack. Disclosed is a battery module including a plate, end separators disposed between the end plates and batteries located at both ends of the battery stack, and a cooling plate connected to each battery in a heat transfer state. ..

In this battery module, the contact area between the end plate and the end separator was reduced by providing a gap in the joint surface between the end plate and the end separator. As a result, the batteries located on both end surfaces of the battery stack are prevented from being cooled by the end plates having excellent heat conductivity more than other batteries, and the variation in the temperature distribution of the plurality of batteries is reduced.

Japanese Unexamined Patent Publication No. 2015-111493

In a battery module, the temperature of a certain battery may rise excessively, the heat may be transmitted to the adjacent battery, and the temperature of this adjacent battery may also rise excessively. In particular, in recent years, there has been a demand for higher capacity of battery modules, and in order to meet this demand, higher capacity of batteries has been advanced. As the capacity of the battery increases, the temperature rise of the battery tends to increase, and thus the chain of overheating is more likely to occur.

As a method of suppressing the chain of overheating, for example, sandwiching a heat insulating material between each battery and suppressing the transfer of heat between adjacent batteries can be considered. However, if the heat transfer between adjacent batteries is suppressed, the temperature distribution tends to vary between the batteries. From the viewpoint of aligning the lives of a plurality of batteries and extending the life of the entire battery module, it is desirable to avoid variations in temperature distribution among the batteries.

The present invention has been made in view of such a situation, and an object thereof is to provide a technique of suppressing a chain of overheating while reducing variations in temperature distribution among a plurality of batteries.

One aspect of the present invention is a battery module. This battery module is a separator that is disposed between a plurality of stacked batteries and two adjacent batteries and electrically insulates the two batteries, and has a heat conduction suppressing portion and a heat conduction promoting portion. A separator and a cooling unit that is thermally connected to the plurality of batteries are provided. The heat conduction suppressing unit has lower heat conductivity than the heat conduction promoting unit and suppresses heat conduction between the two adjacent batteries, and the heat conduction promoting unit abuts the cooling unit and between the two adjacent batteries. It promotes heat conduction and conducts heat from the battery to the cooling unit.

It should be noted that any combination of the above constituent elements and one obtained by converting the expression of the present invention among methods, devices, systems, etc. are also effective as an aspect of the present invention.

According to the present invention, it is possible to suppress a chain of overheating while reducing variations in temperature distribution among a plurality of batteries.

FIG. 3 is a perspective view of the battery module according to the first embodiment. It is an exploded perspective view of a battery module. It is a perspective view which shows a part of battery module typically. It is sectional drawing which shows a part of battery module typically. It is a top view which shows a part of battery module typically. It is sectional drawing which shows a part of battery module typically. FIG. 7 is a cross-sectional view schematically showing a part of the battery module according to the second embodiment. FIG. 9 is a perspective view schematically showing a part of the battery module according to the third embodiment. FIG. 8 is a plan view schematically showing a part of the battery module according to Modification 1.

Hereinafter, the present invention will be described based on preferred embodiments with reference to the drawings. The embodiments do not limit the invention and are exemplifications, and all the features and combinations thereof described in the embodiments are not necessarily essential to the invention. The same or equivalent constituent elements, members, and processes shown in each drawing will be denoted by the same reference numerals, and duplicated description will be appropriately omitted. Further, the scales and shapes of the respective parts shown in the drawings are set for the sake of convenience of description, and should not be construed as limiting unless otherwise specified. In addition, when terms such as “first” and “second” are used in the present specification or claims, the terms do not indicate any order or importance, and have a certain configuration unless otherwise specified. And to distinguish it from other configurations. In addition, in each drawing, some of the members that are not important for explaining the embodiment are omitted.

(Embodiment 1)
FIG. 1 is a perspective view of the battery module according to the first embodiment. FIG. 2 is an exploded perspective view of the battery module. The battery module 1 includes a battery stack 2, a pair of end plates 4, a cooling unit 6, a heat conduction layer 10, and a restraining member 12.

The battery stack 2 has a plurality of batteries 14 and a separator 16. Each battery 14 is a rechargeable secondary battery such as a lithium-ion battery, a nickel-hydrogen battery, a nickel-cadmium battery, or the like. Each battery 14 is a so-called prismatic battery, and has a flat rectangular parallelepiped outer can 18. A not-shown substantially rectangular opening is provided on one surface of the outer can 18, and an electrode body, an electrolytic solution and the like are accommodated in the outer can 18 through this opening. The opening of the outer can 18 is provided with a sealing plate 20 that closes the opening.

The sealing plate 20 has a positive output terminal 22 arranged near one end in the longitudinal direction and a negative output terminal 22 arranged near the other end. Each of the pair of output terminals 22 is electrically connected to a positive electrode plate and a negative electrode plate that form an electrode body. Hereinafter, the positive output terminal 22 is referred to as a positive terminal 22a, and the negative output terminal 22 is referred to as a negative terminal 22b. Further, when it is not necessary to distinguish the polarities of the output terminal 22, the positive electrode terminal 22a and the negative electrode terminal 22b are collectively referred to as the output terminal 22.

The outer can 18, the sealing plate 20, and the output terminal 22 are conductors, and are made of metal, for example. The sealing plate 20 and the opening of the outer can 18 are joined by, for example, laser welding. Each output terminal 22 is inserted into a through hole (not shown) formed in the sealing plate 20. An insulating seal member (not shown) is interposed between each output terminal 22 and each through hole.

In the description of the present embodiment, for convenience, the sealing plate 20 will be referred to as the upper surface of the battery 14, and the bottom surface of the outer can 18 facing the sealing plate 20 will be referred to as the lower surface of the battery 14. Battery 14 also has two main surfaces that connect the upper surface and the lower surface. The main surface has the largest area among the six surfaces of the battery 14. The main surface is a long side surface connected to the long sides of the upper surface and the lower surface. The remaining two surfaces excluding the upper surface, the lower surface and the two main surfaces are the side surfaces of the battery 14. The side surfaces are a pair of short side surfaces connected to the short sides of the upper surface and the lower surface.

Further, for convenience, in the battery stack 2, the surface on the upper surface side of the battery 14 is the upper surface of the battery stack 2, the surface on the lower surface side of the battery 14 is the lower surface of the battery stack 2, and the surface on the side surface side of the battery 14 is the battery. The side surface of the laminated body 2 is used. These directions and positions are defined for convenience. Therefore, for example, in the present invention, the portion defined as the upper surface does not necessarily mean that it is located above the portion defined as the lower surface.

The sealing plate 20 is provided with a valve portion 24 between a pair of output terminals 22. The valve unit 24 is also called a safety valve, and is a mechanism for releasing gas inside the battery 14. The valve portion 24 is configured to open when the internal pressure of the outer can 18 rises above a predetermined value to release the gas inside. The valve portion 24 is composed of, for example, a thin portion provided in a part of the sealing plate 20 and having a smaller thickness than other portions, and a linear groove formed on the surface of the thin portion. In this configuration, when the internal pressure of the outer can 18 rises, the thin portion tears from the groove to open the valve. The valve portion 24 of each battery 14 is connected to an exhaust duct 38 described later, and the gas inside the battery is discharged from the valve portion 24 to the exhaust duct 38.

Each battery 14 also has an insulating film 26. The insulating film 26 is, for example, a cylindrical shrink tube, and is heated after the outer can 18 is passed inside. As a result, the insulating film 26 contracts and covers the two main surfaces, the two side surfaces, and the bottom surface of the outer can 18. The insulating film 26 can suppress a short circuit between the adjacent batteries 14 or between the batteries 14 and the end plate 4 or the restraining member 12.

The plurality of batteries 14 are stacked at a predetermined interval so that the main surfaces of the adjacent batteries 14 face each other. Note that “stacking” means arranging a plurality of members in any one direction. Therefore, stacking the batteries 14 also includes horizontally arranging the plurality of batteries 14. In this embodiment, the batteries 14 are horizontally stacked. Therefore, the stacking direction X of the battery 14 is a direction that extends horizontally. In the following, a direction that is horizontal and perpendicular to the stacking direction X is referred to as a horizontal direction Y, and a direction perpendicular to the stacking direction X and the horizontal direction Y is referred to as a vertical direction Z.

Also, the batteries 14 are arranged so that the output terminals 22 face the same direction. Each of the batteries 14 of the present embodiment is arranged such that the output terminal 22 faces upward in the vertical direction. In this state, the pair of output terminals 22 of each battery 14 are arranged in the horizontal direction Y. Typically, when the adjacent batteries 14 are connected in series, the positive electrode terminal 22a of one battery 14 and the negative electrode terminal 22b of the other battery 14 are laminated so as to be adjacent to each other. When the adjacent batteries 14 are connected in parallel, the positive electrode terminal 22a of one battery 14 and the positive electrode terminal 22a of the other battery 14 are laminated so as to be adjacent to each other.

The separator 16 is also called an insulating spacer and is made of, for example, an insulating sheet. The separator 16 is arranged between two adjacent batteries 14 and electrically insulates the two batteries 14 from each other. The structure of the separator 16 will be described in detail later.

The battery stack 2 is sandwiched between a pair of end plates 4. The pair of end plates 4 are arranged at both ends of the battery stack 2 in the stacking direction X. The pair of end plates 4 are adjacent to the batteries 14 located at both ends in the stacking direction X with the outer end separator 5 interposed therebetween. The outer edge separator 5 is an insulating resin sheet made of a thermoplastic resin such as polypropylene (PP), polybutylene terephthalate (PBT), polycarbonate (PC), Noryl (registered trademark) resin (modified PPE). .. Each end plate 4 is a metal plate made of metal such as iron, stainless steel, and aluminum. The outer end separator 5 is interposed between the end plate 4 and the battery 14 to insulate the both.

Each end plate 4 has a fastening hole 4a on two surfaces facing the horizontal direction Y. In the present embodiment, the three fastening holes 4a are arranged in the vertical direction Z at a predetermined interval. The surface provided with the fastening hole 4a faces a flat surface portion 54 of the restraint member 12 which will be described later.

A bus bar plate 28 is placed on the upper surface of the battery stack 2. The bus bar plate 28 is a plate-shaped member that covers the upper surfaces of the plurality of batteries 14. The bus bar plate 28 has a plurality of openings 32 that expose the valve portions 24 at positions corresponding to the valve portions 24 of each battery 14. Further, the bus bar plate 28 has a duct top plate 34 that covers the upper side of the opening 32 and a side wall 36 that surrounds the side of the opening 32. An exhaust duct 38 is formed in the bus bar plate 28 by fixing the duct top plate 34 to the upper end of the side wall 36. Each valve portion 24 communicates with the exhaust duct 38 via the opening 32.

Further, the bus bar plate 28 has an opening 40 at a position corresponding to the output terminal 22 of each battery 14 to expose the output terminal 22. A bus bar 42 is placed in each opening 40. The plurality of bus bars 42 are supported by the bus bar plate 28. The bus bar 42 placed in each opening 40 electrically connects the positive electrode terminal 22a and the negative electrode terminal 22b of the adjacent batteries 14 to each other.

The bus bar 42 is a substantially strip-shaped member made of metal such as copper or aluminum. The bus bar 42 has one end connected to the positive electrode terminal 22a of the one battery 14 and the other end connected to the negative terminal 22b of the other battery 14. In the bus bar 42, the output terminals 22 of the same polarity in the adjacent batteries 14 may be connected in parallel to form a battery block, and the battery blocks may be connected in series.

The bus bar 42 connected to the output terminals 22 of the batteries 14 located at both ends in the stacking direction X has external connection terminals 44. The external connection terminal 44 is connected to an external load (not shown). Further, the voltage detection line 46 is mounted on the bus bar plate 28. The voltage detection line 46 is electrically connected to the plurality of batteries 14 and detects the voltage of each battery 14. The voltage detection line 46 has a plurality of conducting wires (not shown). One end of each conductive wire is connected to each bus bar 42, and the other end is connected to the connector 48. The connector 48 is connected to an external battery ECU (not shown) or the like. The battery ECU controls detection of the voltage of each battery 14, charging and discharging of each battery 14, and the like.

The cooling unit 6 is a mechanism that is thermally connected to the plurality of batteries 14, that is, is connected to each battery 14 in a heat exchangeable manner and cools each battery 14. Cooling unit 6 of the present embodiment has a structure in which cooling plate 6a and intervening layer 6b are stacked. The cooling plate 6a and the intervening layer 6b are flat plates extending in the stacking direction X and the horizontal direction Y, and are stacked in the vertical direction Z. For example, the cooling plate 6a is made of a metal material having high thermal conductivity such as aluminum. Further, for example, the intervening layer 6b is formed of a known resin sheet having good thermal conductivity and insulating properties such as an acrylic rubber sheet or a silicone rubber sheet. The intervening layer 6b may be made of a known adhesive or grease having good thermal conductivity and insulating properties.

The intervening layer 6b may not have insulating properties. For example, when the outer can 18 is sufficiently insulated by the insulating film 26 or the like, a sheet having no insulating property, an adhesive, grease or the like can be used as the intervening layer 6b. When the outer can 18 is insulated with the insulating film 26 or the like and a sheet or the like having good thermal conductivity and insulating properties is used as the intervening layer 6b, more reliable insulation can be realized.

The cooling unit 6 is arranged on the lower surface side of the battery stack 2, and the battery stack 2 is placed on the main surface of the cooling unit 6. Therefore, the battery stack 2 and the cooling unit 6 are arranged in the vertical direction Z. The intervening layer 6b is interposed between the battery stack 2 and the cooling plate 6a. That is, the cooling plate 6a is thermally connected to the battery stack 2 via the intervening layer 6b. By arranging intervening layer 6b between battery stack 2 and cooling plate 6a, thermal connection between each battery 14 and cooling plate 6a can be obtained more reliably. Therefore, the cooling efficiency of each battery 14 can be improved, and each battery 14 can be cooled more uniformly. Further, since the intervening layer 6b has an insulating property, it is possible to prevent the battery stack 2 and the cooling plate 6a from being electrically connected. When the intervening layer 6b is made of an adhesive or a resin sheet, the intervening layer 6b can also be expected to have an effect of suppressing the displacement between the battery stack 2 and the cooling plate 6a in the extending direction of the XY plane.

The cooling plate 6a is thermally connected to a heat absorbing section 76 (see FIG. 3) described later. For example, the heat absorbing section 76 has a flow path (not shown) inside which a coolant such as water or ethylene glycol flows. This flow path is thermally connected to the outside of the battery module 1. The heat absorbing section 76 absorbs heat from the cooling plate 6a and moves it to the outside of the battery module 1 via the refrigerant. As a result, the cooling efficiency of each battery 14 can be further increased.

The heat conduction layer 10 is disposed between the restraint member 12 and the battery stack 2, and conducts the heat of each battery 14 to the restraint member 12. Further, the heat conduction layer 10 has an insulating property and also functions as a side separator that insulates the restraint member 12 and the battery stack 2. Each of the plurality of batteries 14 has a first surface 14a facing the cooling unit 6 and a second surface 14b different from the first surface 14a. The heat conduction layer 10 is arranged between the restraint member 12 and the second surface 14b of each battery 14. In the present embodiment, the cooling unit 6 faces the lower surface of each battery 14, and the restraint member 12 faces the side surface of each battery 14. Therefore, the first surface 14 a is the lower surface of the battery 14 and the second surface 14 b is the side surface of the battery 14. Therefore, the second surface 14b is a surface continuous with the first surface 14a.

In the present embodiment, a pair of heat conduction layers 10 are arranged in the horizontal direction Y. Each heat conduction layer 10 has a flat plate shape that is long in the stacking direction X of the batteries 14. The battery stack 2 is arranged between the pair of heat conductive layers 10. The heat conducting layer 10 can be made of a resin sheet, an adhesive, grease or the like, like the intervening layer 6b.

The restraint member 12 is also called a bind bar, and is a long member extending in the stacking direction X of the batteries 14. The restraint member 12 is arranged so as to face the second surface 14b (side surface) of each battery 14. In the present embodiment, a pair of restraint members 12 are arranged in the horizontal direction Y. Each restraint member 12 is made of metal. Examples of the metal forming the restraint member 12 include iron and stainless steel. The battery stack 2, the pair of end plates 4, the cooling unit 6, and the pair of heat conduction layers 10 are arranged between the pair of restraining members 12.

The restraint member 12 of the present embodiment has a flat surface portion 54 and a pair of arm portions 56. The plane portion 54 has a rectangular shape and extends in the stacking direction X along the side surface of the battery stack 2. The pair of arm portions 56 protrude toward the battery stack 2 from the end regions on both sides of the flat surface portion 54 in the vertical direction Z. That is, the one arm portion 56 projects from the upper side of the flat surface portion 54 toward the battery stack 2 side, and the other arm portion 56 projects from the lower side of the flat surface portion 54 toward the battery stack body 2 side. Therefore, the pair of arms 56 oppose each other in the arrangement direction of the battery stack 2 and the cooling unit 6. The battery stack 2, the cooling unit 6, and the heat conduction layer 10 are arranged between the pair of arms 56.

A contact plate 68 is fixed by welding or the like to a region of the flat surface portion 54 that faces each end plate 4. The contact plate 68 is a member long in the vertical direction Z. The contact plate 68 is provided with a through hole 70 penetrating the contact plate 68 in the horizontal direction Y at a position corresponding to the fastening hole 4a of the end plate 4. Further, the plane portion 54 has a through hole 58 penetrating the plane portion 54 in the horizontal direction Y at a position corresponding to the through hole 70 of the contact plate 68.

The plurality of batteries 14 are sandwiched in the stacking direction X by the pair of end plates 4 engaging with the flat surface portion 54 of each restraint member 12. Specifically, the plurality of batteries 14 and the plurality of separators 16 are alternately arranged to form the battery laminated body 2, and the battery laminated body 2 is laminated with the pair of end plates 4 via the outer end separator 5 in the laminating direction X. Sandwiched between. Further, the cooling unit 6 is arranged on the lower surface of the battery stack 2. In this state, the battery stack 2 is sandwiched between the pair of heat conduction layers 10 in the horizontal direction Y. Further, the pair of restraint members 12 sandwich the whole in the horizontal direction Y from the outside of the pair of heat conduction layers 10.

The pair of end plates 4 and the pair of restraint members 12 are aligned with each other such that the fastening holes 4a, the through holes 70, and the through holes 58 overlap each other. Then, a fastening member 59 such as a screw is inserted into the through hole 58 and the through hole 70 and screwed into the fastening hole 4a. As a result, the pair of end plates 4 and the pair of restraint members 12 are fixed. By engaging the pair of end plates 4 and the pair of restraint members 12, the plurality of batteries 14 are tightened and restrained in the stacking direction X. As a result, each battery 14 is positioned in the stacking direction X.

Further, the restraint member 12 sandwiches the plurality of batteries 14 in the stacking direction X and also sandwiches the battery stack 2 and the cooling unit 6 in the arrangement direction thereof. Specifically, the restraint member 12 sandwiches the plurality of batteries 14 in the stacking direction X by engaging both ends of the flat portion 54 in the stacking direction X of the batteries 14 with the pair of end plates 4. Further, the restraint member 12 sandwiches the battery stack 2 and the cooling unit 6 in the vertical direction Z by the pair of arms 56. That is, the restraint member 12 has both the function of fastening the plurality of batteries 14 and the function of fastening the battery stack 2 and the cooling unit 6. Therefore, unlike the conventional structure, the battery stack 2 and the cooling unit 6 are not fastened with screws.

In a state where the battery stack 2 and the cooling unit 6 are sandwiched in the vertical direction Z by the pair of arms 56, the intervening layer 6b is pressed by the battery stack 2 and the cooling plate 6a to elastically or plastically deform. Thereby, the thermal connection between the battery stack 2 and the cooling plate 6a can be obtained more reliably. Further, uniform cooling of the entire battery stack 2 can be achieved. Further, the deviation of the battery stack 2 and the cooling plate 6a in the XY plane direction can be further suppressed.

As an example, the bus bar plate 28 is placed on the battery stack 2 after the assembly is completed. Then, the bus bar 42 is attached to the output terminal 22 of each battery 14, and the output terminals 22 of the plurality of batteries 14 are electrically connected to each other. For example, the bus bar 42 is fixed to the output terminal 22 by welding.

A top cover 60 is laminated on the upper surface of the bus bar plate 28. The top cover 60 suppresses contact of dew condensation water, dust, or the like with the output terminal 22, the valve portion 24, the bus bar 42, etc. of the battery 14. The top cover 60 is made of, for example, an insulating resin. The top cover 60 has an insulating cover portion 62 at a position overlapping the external connection terminal 44 in the vertical direction Z. The top cover 60 is fixed to the bus bar plate 28 by, for example, snap fitting. The external connection terminals 44 are covered with the insulating cover portion 62 while the top cover 60 is placed on the bus bar plate 28.

FIG. 3 is a perspective view schematically showing a part of the battery module 1. FIG. 4 is a sectional view schematically showing a part of the battery module 1. In FIG. 4, illustration of the internal structure of the battery 14 is omitted.

The separator 16 has a heat conduction suppressing portion 72 and a heat conduction promoting portion 74. The heat conduction suppressing portion 72 and the heat conduction promoting portion 74 both have an insulating property and are interposed between two adjacent batteries 14. Both the heat conduction suppressing portion 72 and the heat conduction promoting portion 74 are in contact with the main surfaces of two adjacent batteries 14.

The heat conduction suppressing unit 72 has lower heat conductivity than the heat conduction promoting unit 74, and suppresses heat conduction between two adjacent batteries 14. On the other hand, the heat conduction promoting unit 74 has higher heat conductivity than the heat conduction suppressing unit 72, and promotes heat conduction between two adjacent batteries 14. That is, the amount of heat transfer between the two batteries 14 via the heat conduction suppressing unit 72 (the amount of heat passing per unit time or unit area) is smaller than the amount of heat transfer via the heat conduction promoting unit 74. Further, the heat conduction promoting unit 74 contacts the cooling unit 6 and conducts the heat of the battery 14 to the cooling unit 6.

The heat conduction suppressing portion 72 is in the form of a sheet, and is composed of a heat insulating material and a laminated film as an example. The heat insulating material is in the form of a sheet and has a structure in which a porous material such as silica xerogel is carried between the fibers of a fiber sheet made of a non-woven fabric or the like. Silica xerogel has a nano-sized void structure that regulates the movement of air molecules, and has low thermal conductivity. The thermal conductivity of the heat insulating material is about 0.018 to 0.024 W/m·K, which is lower than the thermal conductivity of air. Therefore, by providing the heat conduction suppressing portion 72, it is possible to further suppress the heat conduction between the batteries 14 as compared with the case where the air layer is provided as the heat insulating layer between the two adjacent batteries 14. The heat insulating material is particularly useful as a heat insulating material used in a narrow space.

Also, silica xerogel can stably maintain its structure against external pressure. Therefore, even if the restraint member 12 tightens in the stacking direction X, the heat insulating performance of the heat insulating material can be stably maintained. Therefore, the battery module 1 can suppress the heat conduction between the batteries 14 more stably by including the heat conduction suppressing portion 72 than in the case where the air layer is provided between the batteries 14 as the heat insulating layer. Furthermore, since the heat insulating material has a lower thermal conductivity than that of air, it is possible to obtain the same heat insulating effect with a thinner layer thickness than that of the air layer. Therefore, upsizing of the battery module 1 can be suppressed.

Laminate film is a member that wraps and protects the entire heat insulating material. The laminated film can prevent the porous material in the heat insulating material from falling off from the fiber sheet. The laminate film is made of, for example, polyethylene terephthalate (PET).

Also, the heat conduction suppressing portion 72 has high heat resistance. More specifically, the heat resistance of the heat insulating material is high. More specifically, the fiber sheet contains fibers having a high melting point, the porous material is made of a material having a high melting point, or both. For example, the heat insulating material has a melting point of 300° C. or higher. Specifically, the melting point of the fiber sheet and/or the porous material forming the heat insulating material is 300° C. or higher. In particular, it is preferable to set the melting point of the fibers constituting the fiber sheet to 300° C. or higher. Thereby, even when the heat insulating material is exposed to a high temperature, the fiber sheet can maintain the state of carrying the porous material.

By increasing the heat resistance of the heat conduction suppressing portion 72, the heat conduction suppressing portion 72 can remain even if the battery 14 generates heat. Therefore, the heat conduction suppressing portion 72 can maintain the insulation between the batteries 14. Moreover, the state in which the heat conduction between the adjacent batteries 14 is suppressed can be maintained for a longer period of time.

The heat conduction promoting unit 74 is in the form of a sheet, and is made of, for example, a resin sheet such as polypropylene (PP), polystyrene (PS), polyethylene (PE), and silicone rubber. The heat conductivity of the heat conduction promoting unit 74 is higher than that of the heat conduction suppressing unit 72 and air. Further, preferably, the thickness of the heat conduction promoting portion 74 is equal to or larger than the thickness of the heat conduction suppressing portion 72. As a result, the heat conduction promoting portion 74 can be brought into more reliable contact with the battery 14. Therefore, heat can be transferred more reliably between the adjacent batteries 14. The heat conduction suppressing portion 72 and the heat conduction promoting portion 74 are fixed to each other by adhesion, insert molding, or the like.

In the separator 16 of the present embodiment, the upper area in the vertical direction Z is formed by the heat conduction suppressing portion 72, and the lower area is formed by the heat conduction promoting portion 74. That is, the heat conduction suppressing portion 72 and the heat conduction promoting portion 74 are arranged in the vertical direction Z. Therefore, in the region above each of the batteries 14 in contact with the heat conduction suppressing portion 72, heat transfer to the adjacent batteries 14 is suppressed. On the other hand, in the lower region of each battery 14 which is in contact with the heat conduction promoting portion 74, the transfer of heat to the adjacent battery 14 is promoted.

The first surface 14a of each battery 14, that is, the lower surface, is in direct contact with the intervening layer 6b of the cooling unit 6. Therefore, most of the heat of each battery 14 moves to the intervening layer 6b from each first surface 14a. In addition, a part of the heat of each battery 14 moves to the adjacent battery 14 via the heat conduction promoting unit 74, and moves from the first surface 14a of the moved battery 14 to the intervening layer 6b. Further, the heat conduction promoting portion 74 is in direct contact with the intervening layer 6b. Therefore, a part of the heat of each battery 14 not only moves to the adjacent battery 14 via the heat conduction promoting unit 74, but also moves from the heat conduction promoting unit 74 to the intervening layer 6b. The heat transferred to the intervening layer 6b moves to the cooling plate 6a and is dissipated from the cooling plate 6a to the heat absorbing section 76.

For example, as shown in FIG. 4, it is assumed that the first battery 14P sandwiched between the second battery 14Q and the third battery 14R undergoes thermal runaway. In this case, transfer of heat from the first battery 14P to the second battery 14Q is hindered by the heat conduction suppressing portion 72 arranged between the second battery 14Q and the first battery 14P. Similarly, transfer of heat from the first battery 14P to the third battery 14R is hindered by the heat conduction suppressing unit 72 arranged between the third battery 14R and the first battery 14P.

On the other hand, the heat conduction promoting unit 74 arranged between the second battery 14Q and the first battery 14P promotes the transfer of heat from the first battery 14P to the second battery 14Q. Similarly, transfer of heat from the first battery 14P to the third battery 14R is promoted by the heat conduction promoting unit 74 arranged between the third battery 14R and the first battery 14P. As a result, the heat of the first battery 14P moves from the first surface 14a of the first battery 14P to the cooling unit 6 and also to the second battery 14Q and the third battery 14R on both sides via the heat conduction promoting unit 74. To do. Then, the second battery 14Q and the third battery 14R move from the first surface 14a to the cooling unit 6.

Further, part of the heat transferred to the second battery 14Q moves to the fourth battery 14S adjacent to the second battery 14Q via the heat conduction promoting unit 74, and is also cooled from the first surface 14a of the fourth battery 14S. Move to Part 6. Similarly, part of the heat transferred to the third battery 14R moves to the fifth battery 14T adjacent to the third battery 14R via the heat conduction promoting unit 74, and also from the first surface 14a of the fifth battery 14T. Move to the cooling unit 6. Further, a part of the heat moves from the heat conduction promoting unit 74 to the cooling unit 6 in the process of moving between the adjacent batteries 14.

In this way, by disposing the heat conduction promoting unit 74 in the region of each battery 14 on the cooling unit 6 side and promoting the transfer of heat to the adjacent batteries 14, the temperature difference between the batteries 14 can be reduced. it can. In addition, the heat of each battery 14 is transferred not only from the first surface 14 a of itself but also from the first surface 14 a of the other stacked batteries 14 and the heat conduction promoting unit 74 between the batteries 14 to the cooling unit 6. be able to. Therefore, the cooling efficiency of each battery 14 can be improved. Further, the heat conduction suppressing portion 72 is arranged between two adjacent batteries 14 to limit the area where the heat transfer between the batteries 14 is allowed. Thereby, the temperature of the other battery 14 excessively rises due to the thermal runaway of one of the batteries 14, that is, the chain of overheating can be suppressed.

The size ratio, shape and arrangement of the heat conduction suppressing portion 72 and the heat conduction promoting portion 74 in each separator 16 are appropriately set based on the results of experiments and simulations in consideration of the amount of heat transfer between the adjacent batteries 14. can do. In other words, the size ratio of the heat conduction suppressing part 72 and the heat conduction promoting part 74 is the ratio of the areas of the heat conduction suppressing part 72 and the heat conduction promoting part 74 when the separator 16 is viewed from the stacking direction X. In addition, preferably, the entire separator 16 including the heat conduction suppressing portion 72 and the heat conduction promoting portion 74 has a substantially uniform thickness.

In addition, in the present embodiment, the heat of each battery 14 is transferred to the restraining member 12 by the heat conduction layer 10 arranged between the restraining member 12 and the second surface 14b of each battery 14, that is, the side surface. FIG. 5 is a plan view schematically showing a part of the battery module 1. FIG. 6 is a sectional view schematically showing a part of the battery module 1. In FIG. 6, illustration of the internal structure of the battery 14 is omitted.

As shown in FIG. 5, the heat of each battery 14 moves to the restraint member 12 through the heat conduction layer 10 and is radiated from the restraint member 12 to the outside of the battery module 1. Thereby, the cooling efficiency of the battery 14 can be improved. At this time, a part of the heat of each battery 14 moves to another battery 14 via the restraining member 12. Further, a part of the heat of each battery 14 can move to another battery 14 through the heat conductive layer 10. As a result, the temperature difference between the batteries 14 can be reduced. Further, as shown in FIG. 6, the heat transferred to the restraint member 12 moves inside the restraint member 12 in the direction in which the heat conduction suppressing portion 72 and the heat conduction promoting portion 74 are arranged, that is, in the vertical direction Z. Thereby, the temperature difference in the vertical direction Z in each battery 14 can be reduced.

Further, the restraint member 12 is thermally connected to the cooling unit 6. In the present embodiment, the flat surface portion 54 of the restraint member 12 contacts the side surface of the cooling portion 6, and the lower arm portion 56 contacts the lower main surface of the cooling plate 6a. As a result, the heat of each battery 14 can be transferred to the cooling unit 6 via the restraining member 12. As a result, the cooling efficiency of each battery 14 can be further improved. An insulating sheet (not shown) is interposed between the restraint member 12 and the cooling plate 6a to electrically insulate them.

Also, a part of the heat of each battery 14 can move in the vertical direction Z in the heat conductive layer 10. Therefore, the temperature difference in the vertical direction Z in each battery 14 can be further reduced. Further, the heat conduction layer 10 is thermally connected to the cooling unit 6. In the present embodiment, the lower end of heat conduction layer 10 abuts on intervening layer 6b. Thereby, the heat of each battery 14 can be transferred to the cooling unit 6 via the heat conduction layer 10. As a result, the cooling efficiency of each battery 14 can be further improved.

In the present embodiment, the amount of heat transfer from each second surface 14b of the battery 14 to the restraining member 12 is smaller than the amount of heat transfer from the first surface 14a of the battery 14 to the cooling unit 6. More preferably, the total heat transfer amount from the two second surfaces 14b to the restraining member 12 is smaller than the heat transfer amount from the first surface 14a to the cooling unit 6. For example, the thermal conductivity and dimensions of the heat conductive layer 10 are set so that the amount of heat transfer from the second surface 14b to the restraining member 12 is smaller than the amount of heat transfer from the first surface 14a to the cooling unit 6. As an example, the heat conduction layer 10 is made of a material having lower heat conductivity than the intervening layer 6b. A heat absorbing portion 76 is directly connected to the cooling portion 6. Therefore, the cooling unit 6 has higher heat dissipation efficiency than the restraining member 12. Therefore, by conducting more heat of the battery 14 to the cooling unit 6 than to the restraining member 12, it is possible to more reliably suppress the chain of overheating.

As described above, the battery module 1 according to the present embodiment is arranged between a plurality of stacked batteries 14 and two adjacent batteries 14, and is a separator that electrically insulates the two batteries 14. 16. The separator 16 includes the heat conduction suppressing portion 72 and the heat conduction promoting portion 74, and the cooling portion 6 that is thermally connected to the plurality of batteries 14. The heat conduction suppressing portion 72 has lower heat conductivity than the heat conduction promoting portion 74, and suppresses heat conduction between two adjacent batteries 14. The heat conduction promoting unit 74 contacts the cooling unit 6, promotes heat conduction between two adjacent batteries 14, and conducts heat of the batteries 14 to the cooling unit 6.

In this way, by combining the heat conduction suppressing portion 72 and the heat conduction promoting portion 74 to control the movement of heat between the adjacent batteries 14, while reducing the variation in the temperature distribution among the plurality of batteries 14, It is possible to suppress the contradictory chain of overheating. Further, since the heat conduction promoting portion 74 is in contact with the cooling portion 6, the cooling efficiency of each battery 14 can be improved. Thereby, the chain of overheating can be further suppressed.

Further, for example, when a partition wall is provided on the main surface of the intervening layer 6b so as to match the space between the batteries 14, and this partition wall is used as the heat conduction promoting portion 74, the heat conduction promoting portion 74 is adapted to the expansion and contraction of each battery 14. It is difficult to track the position of. On the other hand, by providing the heat conduction promoting portion 74 in each separator 16, the position of the heat conduction promoting portion 74 can be favorably followed with respect to the expansion and contraction of each battery 14.

Each of the plurality of batteries 14 has a first surface 14a facing the cooling unit 6 and a second surface 14b different from the first surface 14a. The battery module 1 is a restraint member 12 that extends in the stacking direction X of the batteries 14, and is placed so as to face the second surface 14b of each battery 14 and sandwiches the plurality of batteries 14 in the stacking direction X. And a heat conduction layer that is disposed between the restraint member 12 and the second surface 14b of each battery 14 and that conducts the heat of each battery 14 to the restraint member 12. Thereby, the variation in the temperature distribution of the plurality of batteries 14 can be further reduced. In addition, the cooling efficiency of each battery 14 can be increased to further suppress the chain of overheating.

Further, in the battery module 1 of the present embodiment, the amount of heat transfer from the second surface 14b of the battery 14 to the restraining member 12 is smaller than the amount of heat transfer from the first surface 14a of the battery 14 to the cooling unit 6. Thereby, the amount of heat transferred between the adjacent batteries 14 via the restraint member 12 can be suppressed. As a result, the chain of overheating can be further suppressed. Further, the restraint member 12 is thermally connected to the cooling unit 6. Thereby, the cooling efficiency of each battery 14 can be further improved and the chain of overheating can be further suppressed.

(Embodiment 2)
The battery module according to the second embodiment has the same configuration as that of the first embodiment except for the shape of the heat conduction promoting portion 74. Hereinafter, the battery module 1 according to the present embodiment will be described focusing on the configuration different from that of the first embodiment, and common configurations will be briefly described or description thereof will be omitted. FIG. 7 is a sectional view schematically showing a part of the battery module according to the second embodiment. In FIG. 7, illustration of the internal structure of the battery 14 is omitted.

The battery module 1 is arranged between a plurality of stacked batteries 14 and two adjacent batteries 14, and a separator 16 that electrically insulates between the two batteries 14 and is thermally connected to the plurality of batteries 14. The cooling unit 6 is provided. The separator 16 has a heat conduction suppressing portion 72 and a heat conduction promoting portion 74.

The heat conduction promoting unit 74 of the present embodiment has a first portion 78 and a second portion 80. The first portion 78 extends between two adjacent batteries 14. The second portion 80 continuously extends from the first portion 78 between one of the two batteries 14 and the cooling unit 6. Therefore, the separator 16 and the heat conduction promoting portion 74 of this embodiment are L-shaped when viewed in the horizontal direction Y.

More specifically, the first portion 78 extends parallel to the YZ plane and abuts on the main surfaces of two adjacent batteries 14. Further, the upper end of the first portion 78 is connected to the lower end of the heat conduction suppressing portion 72. The second portion 80 extends parallel to the XY plane, and one end portion in the stacking direction X is connected to the lower end of the first portion 78. The upper main surface of the second portion 80 contacts the first surface 14a, and the lower main surface of the second portion 80 contacts the intervening layer 6b. The first surface 14 a of the battery 14 is substantially entirely covered with the second portion 80. The other end of the second portion 80 in the stacking direction X abuts the second portion 80 of the adjacently disposed separator 16.

According to the present embodiment, it is possible to more reliably obtain the state where the heat conduction promoting unit 74 and the cooling unit 6 are in contact with each other. Further, the contact area between the heat conduction promoting portion 74 and the cooling portion 6 can be increased. As a result, the cooling efficiency of each battery 14 can be further improved.

(Embodiment 3)
The battery module according to the third embodiment has the same configuration as that of the first embodiment except for the shape of the heat conduction promoting portion 74. Hereinafter, the battery module 1 according to the present embodiment will be described focusing on the configuration different from that of the first embodiment, and common configurations will be briefly described or description thereof will be omitted. FIG. 8 is a perspective view schematically showing a part of the battery module according to the third embodiment.

The heat conduction promoting unit 74 of the present embodiment has a protrusion 82 that fits into the heat conduction suppressing unit 72. When the separator 16 is viewed from the stacking direction X, the protruding portion 82 is fitted in the heat conduction suppressing portion 72. The projecting portion 82 projects into the heat conduction suppressing portion 72 from the boundary line between the heat conduction suppressing portion 72 and the heat conduction promoting portion 74. Accordingly, the temperature difference in the direction in which the heat conduction suppressing portion 72 and the heat conduction promoting portion 74 in each battery 14 are arranged can be reduced. Further, the protrusion 82 of the present embodiment abuts on the main surfaces of two adjacent batteries 14.

The embodiments of the present invention have been described above in detail. The above-described embodiments are merely specific examples for implementing the present invention. The contents of the embodiments do not limit the technical scope of the present invention, and many design changes such as changes, additions and deletions of components are made without departing from the spirit of the invention defined in the claims. Is possible. The new embodiment in which the design change is added has the effect of each of the combined embodiment and the modification. In the above-mentioned embodiment, the contents such as “design change” are emphasized with the notation “of this embodiment”, “in this embodiment”, etc. Design changes are allowed even if there is no content. Any combination of the constituent elements included in each embodiment is also effective as an aspect of the present invention. The hatching attached to the cross section of the drawing does not limit the material to which the hatching is attached.

(Modification 1)
FIG. 9 is a plan view schematically showing a part of the battery module according to Modification 1. The heat conductive layer 10 has a plurality of first members 84 and a second member 86. Each of the plurality of first members 84 has a strip shape that is long in the vertical direction Z, and is arranged in the stacking direction X at a predetermined interval. Each first member 84 contacts the second surface 14b of each battery 14. The second member 86 has a flat plate shape and is interposed between the restraining member 12 and each of the first members 84.

At least one of the first member 84 and the second member 86 has an insulating property. Preferably, both the first member 84 and the second member 86 have insulating properties. Further, preferably, each first member 84 has higher thermal conductivity than the second member 86. As a result, the amount of heat transferred in the stacking direction X in the heat conductive layer 10 can be reduced while promoting heat transfer from each battery 14 to the restraining member 12. Thereby, the chain of overheating can be further suppressed.

(Other)
The number of batteries 14 included in the battery module 1 is not particularly limited. The fixing structure of the end plate 4 and the restraint member 12 is not particularly limited, and a well-known structure can be adopted. Typically, fixing structures other than the structures disclosed in the embodiments include fixing using bolts and rivets, welding, and mechanical clinch. The battery 14 may be cylindrical or the like. When sufficient heat conduction and frictional force between the battery stack 2 and the cooling plate 6a can be ensured, the intervening layer 6b is omitted, and an insulating sheet made of PET or PC is used as the battery stack 2 and the cooling plate 6a. It may be interposed between and.

1 battery module, 6 cooling section, 10 heat conduction layer, 12 restraint member, 14 battery, 14a first side, 14b second side, 16 separator, 72 heat conduction suppressing section, 74 heat conduction promoting section, 78 heat conduction promoting section, 78 first section, 80 second part, 82 protruding part.

Claims

A plurality of stacked batteries,
A separator that is arranged between two adjacent batteries and electrically insulates the two batteries from each other, the separator having a heat conduction suppressing portion and a heat conduction promoting portion,
A cooling unit thermally connected to the plurality of batteries,
The heat conduction suppressing portion has lower heat conductivity than the heat conduction promoting portion, and suppresses heat conduction between two adjacent batteries,
The battery module, wherein the heat conduction promoting unit is in contact with the cooling unit, promotes heat conduction between two adjacent batteries, and conducts heat of the battery to the cooling unit.
The heat conduction promoting unit extends between a first portion extending between two adjacent batteries, and between one battery of the two batteries and the cooling unit continuously from the first portion. The battery module according to claim 1, further comprising:
The battery module according to claim 1 or 2, wherein the heat conduction promoting portion has a protrusion that fits into the heat conduction suppressing portion.
Each of the plurality of batteries has a first surface facing the cooling unit and a second surface different from the first surface,
The battery module is a restraint member extending in the stacking direction of the batteries, the restraint member being arranged so as to face the second surface of each battery and sandwiching the plurality of batteries in the stacking direction.
The heat conductive layer which is arrange|positioned between the said restraint member and the said 2nd surface of each battery, and which conducts the heat|fever of each battery to the said restraint member is provided. Battery module.
The battery module according to claim 4, wherein a heat transfer amount from the second surface of the battery to the restraining member is smaller than a heat transfer amount from the first surface of the battery to the cooling unit.
The battery module according to claim 4 or 5, wherein the restraint member is thermally connected to the cooling unit.