WO2019139098A1 - Battery pack and electric ally drivenmotor device - Google Patents

Abstract

This battery pack (10) is provided with a plurality of unitsingle cells (1) and heat diffusion sheets (3) which are directly or indirectly in contact with at least two of the unitsingle cells (1). The heat diffusion sheets (3) have a thermal conductivity higher than the thermal conductivity of the contacted surfaces of the unitsingle cells (1).

Description

Battery pack and motorized device

The present invention relates to an assembled battery and an electrically powered device.
Priority is claimed on Japanese Patent Application No. 2018-002191, filed January 10, 2018, the content of which is incorporated herein by reference.

In recent years, while awareness of the environment has increased, as described in, for example, Patent Document 1, a secondary battery such as a lithium ion battery has attracted attention as a storage battery for storing electrical energy.

JP 2000-357494 A

In a storage battery for an electric vehicle or the like, a battery pack configured by connecting a plurality of single cells (lithium ion battery or the like) is used to increase the capacity. In a battery pack, since a plurality of single cells are gathered, it is easy to become high temperature by heat generation at the time of energization. Batteries, such as lithium ion batteries, may deteriorate at high temperatures.

The battery assembly may have a temperature distribution with a large temperature difference among the cells depending on the arrangement of the cells. If the temperature difference between the unit cells is large, the temperature of some of the unit cells becomes high, and the unit cells reach the end of their lifespan, resulting in a problem that the entire service life of the assembled battery is shortened.

An object of the present invention is to provide an assembled battery and a motor-driven device having a small temperature difference between single cells.

The assembled battery according to one aspect of the present invention includes a plurality of single cells and a heat diffusion sheet in direct or indirect contact with two or more of the plurality of single cells, and the heat diffusion sheet includes the single cells. The thermal conductivity is higher than the thermal conductivity at the contact surface of

The assembled battery further includes a battery case for covering the unit cell, and the battery case is interposed between the unit cell and the heat diffusion sheet to be in contact with the heat diffusion sheet, and the heat diffusion unit is provided. The sheet may have a thermal conductivity higher than the thermal conductivity of the contact surface of the battery case instead of the contact surface of the unit cell.
The heat diffusion sheet may be a graphite sheet made of graphite.

The battery assembly may have a stacked structure in which a plurality of layers formed of the two or more unit cells are stacked, and the heat diffusion sheet may be provided between the plurality of layers.

The battery pack includes at least a pair of facing package plates, and the package plates abut each other at a plurality of contact portions at intervals in the width direction, and are partitioned by the contact portions. The single battery may be accommodated in each of the plurality of cylindrical portions.

The battery pack may be provided with a protection plate for closing the opening of the tubular portion on one side and the other side of the tubular portion.

In the assembled battery, the unit cell includes a battery body and a container having an internal space for housing the battery body, and the container is formed of a laminate in which a metal layer and a resin layer are stacked, The resin layer may be on the side of the inner space.

An electric device according to an aspect of the present invention includes the battery assembly and a drive mechanism driven by the battery assembly.

According to one aspect of the present invention, by diffusing more heat from the unit cells having a relatively large calorific value by the heat diffusion sheet, the temperature difference between the unit cells constituting the assembled battery can be reduced.

It is a front view which shows the assembled battery of one embodiment of the present invention typically. FIG. 2 is a cross-sectional view taken along line II of FIG. It is a perspective view which shows the example of the cell used for the assembled battery of FIG. It is a front view which shows typically a part of 1st modification of the assembled battery of FIG. It is a front view which shows typically a part of 2nd modification of the assembled battery of FIG. It is a front view which shows typically a part of 3rd modification of the assembled battery of FIG. It is a perspective view which shows the assembled battery of other embodiment of this invention typically. It is a figure which shows typically the electrically-driven apparatus of one Embodiment of this invention. It is a graph which shows the change of the battery temperature in one Example of this invention. It is a graph which shows the change of the battery temperature in a comparative example. It is a graph which shows the temperature difference of the cell with the highest temperature, and the cell with the lowest temperature in an Example and a comparative example.

FIG. 1 is a front view schematically showing a battery pack 10 according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line II of FIG. FIG. 3 is a perspective view showing an example of the unit cell 1 used in the battery assembly 10. As shown in FIG.

As shown in FIG. 1, the battery assembly 10 includes a plurality of rectangular battery cells 1 arranged in parallel to one another, a battery outer package 2 arranged to wrap each single battery 1, and a battery outer package 2. And a pair of protective plates 4 sandwiching the battery outer package 2 from both sides, and a fixing tool 5 connecting the end portions of the protective plates 4 to each other.

The battery assembly 10 includes one or more battery outer casings 2. The assembled battery 10 of the embodiment shown in FIG. 1 includes three battery outer casings 2 arranged in three layers. The battery case 2 is referred to as a first battery case 2A, a second battery case 2B, and a third battery case 2C in order from the top in FIG. The first to third battery outer packages 2A to 2C have the same planar dimensions and thickness, and are stacked in parallel in the thickness direction (Z direction).

The battery exterior body 2 includes a pair of facing rectangular exterior plates 6 and 6, and a plurality of (three in this example) single cells 1 are parallel to each other between the pair of exterior plates 6 and 6. They are spaced apart.
The exterior plates 6, 6 constituting the first battery exterior body 2A are referred to as first and second exterior plates 6A, 6B in order from the top in FIG. The exterior plates 6, 6 constituting the second battery exterior body 2B are referred to as third and fourth exterior plates 6C, 6D in order from the top in FIG. The exterior plates 6, 6 constituting the third battery exterior body 2C are referred to as fifth and sixth exterior plates 6E, 6F in order from the top in FIG.

The exterior plate 6 is not limited in the present invention, but is made of, for example, metal, non-metal material (for example, resin), and the like.
The metal constituting the exterior plate 6 may be, for example, copper, nickel, iron, stainless steel, aluminum or the like, or an alloy containing one or more of them or a composite material thereof.

Non-metal materials constituting the exterior plate 6 are not limited in the present invention, but polyester resins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT); Polyolefin resins such as polypropylene; Nylon Polyamide resins such as (Ny); polyimide resins; fluorine resins; acrylic resins; polyurethane resins and the like.

The exterior plate 6 may have a single-layer structure or a multilayer structure in which the same or different materials are stacked. The exterior plate 6 may be a multilayer structure including a metal layer and a nonmetal layer. As shown in FIG. 2, the exterior plate 6 of this embodiment is formed in a rectangular shape, for example, a rectangular shape in a plan view.

In FIGS. 1 and 2, the X direction is the width direction of the exterior plate 6. The Y direction is an extending direction orthogonal to the X direction in a plane along the exterior plate 6 (for example, the substrate unit 11). The Z direction is a direction orthogonal to the X direction and the Y direction, and is a thickness direction of the exterior plate 6. Planar view refers to viewing from the Z direction.

The facing plates 6, 6 face each other at a plurality of contact portions 7 in the gap between the unit cells 1 adjacent in the X direction. The contact portion 7 may be joined, or the cover plates 6 and 6 may be separable only by contact. The contact portion 7 is formed in, for example, a band shape having a constant width along the Y direction. The plurality of contact portions 7 are formed at intervals in the X direction, and each contact portion 7 is located at the center of the gap between adjacent single cells 1.

The portion of the exterior plate 6 between the contact portions 7 adjacent to each other in the X direction is referred to as an intermediate portion 8 (non-contact portion). The intermediate portion 8 includes a parallel substrate portion 11 in surface contact with the upper surface and the lower surface of the unit cell 1, and a pair of side plate portions 12 which connect the substrate portion 11 and the contact portion 7 and are inclined relative to the substrate portion 11 And 12. The pair of side plates 12, 12 in the illustrated example have the same width, but may have different widths.

The substrate unit 11 is formed along the XY plane. The inner surface (lower surface in FIG. 1) of the substrate portion 11 of the first, third and fifth exterior plates 6A, 6C, 6E is one surface (upper surface in FIG. 1) of the unit cell 1 (1A, 1B, 1C) Face contact with The inner surfaces (upper surface in FIG. 1) of the second, fourth and sixth exterior plates 6B, 6D, 6F are in surface contact with the other surfaces (lower surface in FIG. 1) of the unit cells 1 (1A, 1B, 1C) respectively. ing.

The side plate portions 12 extend from the side edges of the substrate portion 11 toward the contact portions 7, respectively. The side plates 12, 12 extend obliquely from the side edges of the base plate 11 so as to gradually come close to the exterior plate 6 on the other side in the widthwise direction. The side plate portions 12, 12 in this example have a flat shape in which the XZ cross section is linear, and are inclined with respect to the substrate portion 11 at an angle θ1 (0 ° <θ1 <90 °). The intermediate portion 8 has a bent shape that is convex in the direction (outward) away from the exterior plate 6 on the opposite side with respect to the XY plane passing through the adjacent contact portions 7. The cross-sections of the side plate portions 12, 12 are not limited to the linear shape, and in some cases may have a slight degree of slack.

The middle portions 8 and 8 of the facing plates 6 and 6 form a hollow rectangular tubular portion 14. The internal space of the cylindrical portion 14 is a battery accommodating portion 15, and the single battery 1 is accommodated in each of the battery accommodating portions 15 one by one. The cylindrical portion 14 is divided by the contact portions 7 and 7. The facing plates 6 and 6 have two or more cylindrical portions 14 arranged in the width direction (X direction). The number of cylindrical portions formed by the pair of facing exterior plates is preferably 2 or more, and can be, for example, 2 to 200.

In the battery assembly 10 shown in FIG. 1, the exterior plates 6, 6 constituting the battery exterior body 2 are in contact with each other at four contact portions 7 at intervals in the X direction. Therefore, the battery case 2 has three cylindrical portions 14. The exterior plates 6 and 6 are each continuously formed in the width direction across the plurality of cylindrical portions 14.

Since the side plate portions 12 and 12 are inclined, the cylindrical portion 14 has a hexagonal cylindrical shape formed of a pair of substrate portions 11 and four side plate portions 12. One intermediate portion 8 has a substrate portion 11 and a pair of side plate portions 12 inclined so as to approach the sheet body on the other side in the widthwise direction, and the other intermediate portion 8 is a substrate portion 11; When it has a pair of side plate parts 12 inclined so that the sheet body on the other side may be approached to the width direction, the shape of the middle part constituted of these substrate parts and side plate parts becomes a hexagonal cylindrical shape.

The abutments 7, 7 can also be glued together with an adhesive. As an adhesive for bonding the contact portions 7, 7, for example, polyolefin adhesive, urethane adhesive, epoxy adhesive, acrylic adhesive, urethane adhesive, nylon adhesive, polyester adhesive Insulating materials, such as an agent, can be mentioned. When the contact parts 7 and 7 are metal, they may be joined not only by adhesion but also by welding, brazing, diffusion bonding or the like.

In the battery exterior body 2, since the plurality of cylindrical portions 14 are arranged at equal intervals in the width direction (X direction) of the exterior plate 6, a honeycomb shape in which the plurality of cylindrical portions 14 are regularly arranged It is a structure.

The number of the battery package 2 (a pair of package plates 6, 6) is preferably 2 or more, and may be, for example, 2 to 20.
The assembled battery 10 includes two or more battery exterior bodies 2, and each battery exterior body 2 includes two or more cylindrical portions 14. A plurality of battery groups consisting of a plurality of unit cells 1 arranged in parallel may be prepared and arranged in series. For example, in the assembled battery 10 shown in FIG. 1, the three single batteries 1A provided in the first battery outer package 2A can be connected in parallel to each other. The three single cells 1B provided in the second battery case 2B can be connected in parallel to each other. The three single cells 1C provided in the third battery case 2C can be connected in parallel with each other. A battery group consisting of a plurality of single cells 1A, a battery group consisting of a plurality of single cells 1B, and a battery group consisting of a plurality of single cells 1C can be connected in series.

As shown in FIG. 3, the unit cell 1 may be, for example, a lithium ion battery. The unit cell 1 of this embodiment includes a rectangular parallelepiped battery body 50 and a container 51 that encloses the battery body 50.
The container 51 has a tray-like container main body 52 having a square recess into which the battery main body 50 is inserted, and a flat cover 53 having the same planar dimensions as the container main 52. I'm closing the hollow. The housing body 51 has an internal space for housing the battery body 50. The container 51 is formed by overlapping the container body 52 and the lid 53 and heat-sealing the peripheral portions 54 of both.
The code | symbol 55 is a positive electrode lead connected to the electrode (positive electrode) of the battery main body 50. As shown in FIG. Reference numeral 56 denotes a negative electrode lead connected to the electrode (negative electrode) of the battery body 50. The positive electrode lead 55 and the negative electrode lead 56 in this example extend parallel to each other from one end of the housing 51.

The battery body 50 includes, for example, a positive electrode plate (not shown), a positive electrode active material layer (not shown) in contact with the positive electrode plate, a negative electrode plate (not shown), and a negative electrode active material layer (not shown) in contact with the negative electrode plate. And a separator (not shown) separating the positive electrode active material layer and the negative electrode active material layer, and an electrolyte (not shown). The positive electrode plate and the negative electrode plate are made of, for example, metal. The positive electrode active material layer contains, for example, a positive electrode active material such as a lithium-based material. The negative electrode active material layer contains, for example, a negative electrode active material such as a carbon-based material. The battery body 50 preferably has a flat shape and a constant thickness.

For example, as shown in FIG. 3, the container main body 52 and the lid 53 constituting the container 51 may be formed of a laminate including the metal layer 57 and the resin layer 58 laminated on the metal layer 57. Good. The metal layer 57 is made of metal such as aluminum or stainless steel. The resin layer 58 is made of a resin such as polyethylene or polypropylene. The container 51 is configured with the resin layer 58 on the inner space side.
Although not shown, the laminate includes a metal layer, a first resin layer laminated on a first surface of the metal layer, and a second surface of the metal layer (surface opposite to the first surface). It may be a structure provided with a second resin layer laminated on (i.e., a structure of resin layer / metal layer / resin layer). This structure is preferable from the viewpoint of processability and durability of the laminate.

The unit cell 1 has a flat shape, and is accommodated in the battery accommodating portion 15 (see FIG. 1) of the battery exterior body 2 with the thickness direction directed in the Z direction. The flat shape of the unit cell 1 means that the thickness dimension (dimension in the Z direction) of the unit cell 1 is smaller than the dimension in the width direction (X direction) and the dimension in the extension direction (Y direction) . Since the unit cell 1 has a flat shape, the assembled battery 10 can be thinned.

As shown in FIG. 1, the unit cells 1 are accommodated one by one in the battery accommodating portion 15 and packaged in the battery exterior body 2. It is preferable that the unit cell 1 be accommodated in the battery accommodating portion 15 so as to be freely put in and out. The unit cell 1 provided in the cylindrical portion 14 of the first battery case 2A is referred to as a first unit cell 1A. The unit cell 1 provided in the cylindrical portion 14 of the second battery exterior body 2B is referred to as a second unit cell 1B. The unit cell 1 provided in the cylindrical portion 14 of the third battery exterior body 2C is referred to as a third unit cell 1C.

A plurality of battery case bodies 2 (2A to 2C) having a plurality of cylindrical portions 14 are overlapped in the thickness direction (Z direction). Therefore, a plurality of unit cells 1 provided in the same battery outer package 2 constitute one layer, and the assembled battery 10 has a laminated structure in which a plurality of layers constituted by a plurality of unit cells 1 are stacked. In addition, the structure of the single battery in this invention is not limited only to the structure of FIG.

The thermal diffusion sheet 3 shown in FIGS. 1 and 2 preferably contains, for example, a carbon-based material such as graphite. The heat diffusion sheet 3 is more preferably a graphite sheet. The graphite sheet is a thin sheet of graphite and has a very high thermal conductivity in the planar direction. Although a graphite sheet containing no binder is preferable in order to enhance the thermal conductivity, a graphite sheet containing a binder such as a resin can also be used.
As graphite constituting the graphite sheet, either natural graphite or synthetic graphite can be used. The thickness of the graphite sheet is, for example, preferably 10 to 1000 μm, more preferably 20 to 500 μm, and still more preferably 40 to 300 μm. The heat diffusion sheet 3 may be made of the above-described thickness by laminating two or more layers of graphite sheets with an adhesive or the like. Natural graphite is inexpensive, and synthetic graphite has few impurities and is excellent in physical properties. Therefore, natural graphite can be selected in consideration of applications, performance, and the like. Both may be used in combination. A thin film of an insulating material such as a plastic or an inorganic material may be formed on the front surface and / or the back surface of the graphite sheet to enhance the insulating property.

The heat diffusion sheet 3 is provided along the XY plane between the battery exteriors 2 and 2 adjacent in the thickness direction (Z direction). The thermal diffusion sheet 3 provided between the first battery exterior body 2A and the second battery exterior body 2B is referred to as a first thermal diffusion sheet 3A. The thermal diffusion sheet 3 provided between the second battery exterior body 2B and the third battery exterior body 2C is referred to as a second thermal diffusion sheet 3B.

As shown in FIG. 2, the thermal diffusion sheet 3 is formed, for example, in a rectangular shape, for example, in a rectangular shape in a plan view. The side edges 3a, 3a of the heat diffusion sheet 3 reach the side edges 2a, 2a of the battery outer package 2 in a plan view. The edges 3 b and 3 b of the heat diffusion sheet 3 reach the edges 2 b and 2 b of the battery outer package 2 in plan view. It is preferable that at least a part of the peripheral edge of the thermal diffusion sheet 3 reaches the peripheral edge of the battery outer package 2 in a plan view.

The upper surface of the first heat diffusion sheet 3A is in surface contact with the outer surfaces (lower surface, contact surface) of all the substrate portions 11 of the second exterior plate 6B. Therefore, the first heat diffusion sheet 3A is indirectly in surface contact with the lower surfaces of all the first single cells 1A via the second exterior plate 6B. The lower surface of the first heat diffusion sheet 3A is in surface contact with the outer surfaces (upper surface, contact surface) of all the substrate portions 11 of the third exterior plate 6C. Therefore, the first heat diffusion sheet 3A is indirectly in surface contact with the upper surfaces of all the second cells 1B via the third exterior plate 6C.

The first thermal diffusion sheet 3A is in direct or indirect contact with at least one of the unit cells 1 (for example, the unit cells 1B1 and 1B3 in FIG. 1) located closest to the end, and the most end Preferably, at least one of the unit cells 1 (for example, the central unit cell 1B2 of FIG. 1) located inside the side is also in direct or indirect contact.

The upper surface of the second heat diffusion sheet 3B is in surface contact with the outer surfaces (lower surface, contact surface) of all the substrate portions 11 of the fourth exterior plate 6D. Therefore, the second heat diffusion sheet 3B is indirectly in surface contact with the lower surfaces of all the second cells 1B via the fourth exterior plate 6D. The lower surface of the second heat diffusion sheet 3B is in surface contact with the outer surfaces (upper surface, contact surface) of all the substrate portions 11 of the fifth exterior plate 6E. Therefore, the second heat diffusion sheet 3B is indirectly in surface contact with the upper surfaces of all the third cells 1C via the fifth exterior plate 6E.

The thermal diffusion sheet 3 is in direct or indirect contact with at least one of the unit cells 1 located on the most end side in the X direction, and the unit cell 1 of the unit cells 1 located on the innermost side than the end side. Preferably, at least one of them is in direct or indirect contact.

The characteristics of the graphite sheet include, for example, the thermal conductivity in the planar direction of 100 to 3000 W / (m · K) and the thermal conductivity in the thickness direction of 1 to 30 W / (m · K). Since the graphite sheet is crystalline having a layered structure as a whole and has a crystal axis (c axis) in which monoatomic layers are stacked in the thickness direction, its physical properties are large in the thickness direction and in the plane direction It shows anisotropy. Examples of the method of measuring the thermal conductivity include ASTM D5470, ASTM E1530, JIS R2616, ASTM D5930, JIS R1611. Examples of the thermal conductivity measurement apparatus include TIM Tester (Model 1300) manufactured by AG, DTC-300 manufactured by TA Instruments, and QTM-500 manufactured by Kyoto Electronics Industry.

The thermal diffusion sheet 3 has a thermal conductivity higher than the thermal conductivity of the contact surface of the exterior plate 6 (specifically, the substrate portion 11). Thus, the thermal diffusion sheet 3 can efficiently diffuse the heat generated in the unit cell 1 and passing through the substrate portion 11 in the thickness direction in the planar direction of the thermal diffusion sheet 3.

The protective plate 4 is provided on the outer surface side (upper surface side) of the first battery outer package 2A and on the outer surface side (lower surface side) of the third battery outer package 2C. The protective plate 4 is, for example, a metal plate made of a material having excellent corrosion resistance and strength, such as stainless steel. The protective plate 4 protects the battery case 2 and the cell 1 from external force.

The fixture 5 includes a bolt 5A and a nut 5B. The fixing tool 5 connects the pair of protective plates 4 and 4 by the bolt 5A and the nut 5B, and increases the contact pressure of each cell 1, the battery outer package 2, the thermal diffusion sheet 3 and the protective plate 4 Are closely attached to each other to enhance the heat dissipation.

The battery assembly 10 includes the thermal diffusion sheet 3 having a thermal conductivity higher than that of the exterior plate 6. Therefore, the heat generated by the unit cell 1 and passed through the exterior plate 6 in the thickness direction is It is possible to diffuse in the direction along the plane of the diffusion sheet 3 and to suppress the temperature rise of the unit cell 1 at the time of energization. Therefore, the temperature difference between the plurality of unit cells 1 can be reduced.

As shown in FIG. 1, the battery assembly 10 has a laminated structure in which a plurality of battery exterior bodies 2 (2A to 2C) each having a plurality of cylindrical portions 14 are stacked in the thickness direction, so It is difficult for the battery 1 to dissipate heat. For example, attention is focused on the second unit cell 1B (central unit cell 1B2) accommodated in the central cylindrical portion 14 among the three cylindrical portions 14 of the second battery exterior body 2B. There are other cells 1 (a first cell 1A and a third cell 1C) in both (upper and lower) in the thickness direction (Z direction) of the central cell 1B2. There are other cells 1 (cell 1B1 and 1B3) in both (left and right) in the width direction (X direction) of the central cell 1B2. Therefore, the central unit cell 1B2 is less likely to release heat and tends to have a higher temperature than the other unit cells 1.

In the battery assembly 10 shown in FIG. 1, since the thermal diffusion sheet 3 (the first thermal diffusion sheet 3A and the second thermal diffusion sheet 3B) is provided, for example, the heat of the central unit cell 1B2 can be widely diffused. Therefore, in the battery assembly 10, the temperature difference between the plurality of unit cells 1 can be reduced, and the uniformity of the temperature of the unit cells 1 can be maintained. Further, since the battery assembly 10 is a battery assembly including a plurality of battery outer casings 2 each having a plurality of cylindrical portions 14, the battery assembly 10 has high strength against physical impact and piercing.

FIG. 4 is a front view schematically showing a part of an assembled battery 10A which is a first modification of the assembled battery 10 shown in FIG. As shown in FIG. 4, the assembled battery 10A has the same configuration as the assembled battery 10 shown in FIG. The assembled battery 10A includes three battery outer casings 102. The battery case 102 is referred to as a first battery case 102A, a second battery case 102B, and a third battery case 102C in order from the top in FIG. The first to third battery outer covers 102A to 102C are stacked in the thickness direction (Z direction).

The battery case 102 includes a pair of facing plates 106, 106 facing each other. The exterior boards 106 and 106 which comprise the 1st battery exterior body 102A are called 1st and 2nd exterior boards 106A and 106B in an order from the top. The exterior boards 106 and 106 which comprise the 2nd battery exterior body 102B are called 3rd and 4th exterior board 106C, 106D sequentially from the top. The exterior plates 106 and 106 constituting the third battery exterior body 102C are referred to as fifth and 106th exterior plates 106E and 106F in order from the top.

Similar to the exterior plate 6 of the battery assembly 10, the exterior plate 106 is made of, for example, a metal, a nonmetal material (for example, a resin), or the like.

The first, third and fifth exterior plates 106A, 106C and 106E are in contact with the second, fourth and sixth exterior plates 106B, 106D and 106F at the plurality of abutment portions 107, respectively. The contact portion 107 is formed, for example, in a band shape having a constant width along the Y direction. The plurality of contact portions 107 are formed at intervals in the X direction.

The portion of the exterior plates 106A, 106C, 106E between the contact portions 107, 107 adjacent in the X direction is called an intermediate portion 108 (non-contact portion). The intermediate portion 108 includes a substrate portion 111 and a pair of side plate portions 112 and 112 inclined with respect to the substrate portion 111.

The substrate portion 111 is formed along the XY plane. The inner surface (lower surface in FIG. 4) of the substrate portion 111 of the first, third and fifth exterior plates 106A, 106C, 106E is one surface (upper surface in FIG. 4) of the unit cell 1 (1A, 1B, 1C) Make face contact with The second, fourth and sixth exterior plates 106B, 106D and 106F are formed flat. The inner surfaces (upper surface in FIG. 4) of the exterior plates 106B, 106D, 106F are in surface contact with the other surfaces (lower surface in FIG. 4) of the unit cells 1 (1A, 1B, 1C).

The side plate portions 112 and 112 of the exterior plates 106A, 106C and 106E extend from the side edges of the substrate portion 111 toward the contact portions 107 and 107, respectively. The side plate portions 112 and 112 extend from the both side edges of the base plate portion 111 so as to gradually approach the mating exterior plate 106 (exterior plates 106B, 106D, and 106F) in the direction of widening.

The intermediate portion 108 of the exterior plates 106A, 106C, and 106E and the exterior plates 106B, 106D, and 106F form a hollow rectangular tubular portion 114. An internal space of the cylindrical portion 114 is a battery housing portion 115. The cylindrical portion 114 is divided by the contact portions 107 and 107. The facing plates 106 and 106 have two or more cylindrical portions 114 arranged in the width direction (X direction). Since the side plate portions 112 and 112 are inclined, the cylindrical portion 114 has a trapezoidal cylindrical shape.

The upper surface of the first heat diffusion sheet 3A is in surface contact with the outer surface (lower surface, contact surface) of the second exterior plate 106B. Therefore, the first heat diffusion sheet 3A is indirectly in surface contact with the lower surfaces of all the first single cells 1A via the second exterior plate 106B. The lower surface of the first heat diffusion sheet 3A is in surface contact with the outer surfaces (upper surface, contact surface) of all the substrate portions 111 of the third exterior plate 106C. Therefore, the first heat diffusion sheet 3A is indirectly in surface contact with the upper surfaces of all the second cells 1B via the third exterior plate 106C.

The upper surface of the second heat diffusion sheet 3B is in surface contact with the outer surface (lower surface, contact surface) of the fourth exterior plate 106D. Therefore, the second heat diffusion sheet 3B is indirectly in surface contact with the lower surfaces of all the second cells 1B via the fourth exterior plate 106D. The lower surface of the second heat diffusion sheet 3B is in surface contact with the outer surface (upper surface, contact surface) of all the substrate portions 111 of the fifth exterior plate 106E. Therefore, the second heat diffusion sheet 3B is in surface contact indirectly with the upper surfaces of all the third cells 1C via the fifth exterior plate 106E.

The thermal diffusion sheet 3 has a thermal conductivity higher than the thermal conductivity of the contact surface of the exterior plate 106 (specifically, the substrate portion 111). Thus, the thermal diffusion sheet 3 can diffuse the heat generated in the unit cell 1 in the in-plane direction.

Since the battery pack 10A shown in FIG. 4 includes the thermal diffusion sheet 3 having a thermal conductivity higher than that of the exterior plate 106, the heat generated by the unit cell 1 is diffused by the thermal diffusion sheet 3 to obtain the plurality of unit cells 1 The temperature difference between the cells 1 can be reduced, and the temperature uniformity among the cells 1 can be maintained. Further, since the battery assembly 10A is a battery assembly including a plurality of battery outer casings 102 each having a plurality of cylindrical portions 114, the battery assembly 10A has high strength against physical impact and piercing.

FIG. 5 is a front view schematically showing a part of an assembled battery 10B which is a second modification of the assembled battery 10 shown in FIG. 1 and the like. As shown in FIG. 5, the assembled battery 10B has the same configuration as the assembled battery 10 shown in FIG. 1 etc. except that a battery outer package 202 (202A to 202C) consisting of flat outer plates 206 and 206 is used.

The thermal diffusion sheet 3 (3A, 3B) is indirectly in surface contact with the cell 1 (1A, 1B, 1C) via the exterior plate 206.

The heat diffusion sheet 3 has a thermal conductivity higher than the thermal conductivity of the contact surface of the exterior plate 206. Thus, the thermal diffusion sheet 3 can diffuse the heat generated in the unit cell 1 in the in-plane direction.

The battery pack 10B shown in FIG. 5 includes the thermal diffusion sheet 3 having a thermal conductivity higher than that of the exterior plate 206, so that the heat generated by the unit cell 1 is diffused by the thermal diffusion sheet 3 The temperature difference between the cells 1 can be reduced, and the temperature uniformity among the cells 1 can be maintained.

FIG. 6 is a front view schematically showing a part of an assembled battery 10C which is a third modification of the assembled battery 10 shown in FIG. 1 and the like. As shown in FIG. 6, the assembled battery 10C has the same structure as the assembled battery 10 shown in FIG. 1 etc. except that the battery outer package 2 is not used.

The thermal diffusion sheet 3 is in direct contact with the unit cells 1 (1A, 1B, 1C). That is, the thermal diffusion sheet 3 is in contact with the outer surface of the container 51 (see FIG. 3) of the unit cell 1.

The upper surface of the first heat diffusion sheet 3A is in surface contact with the lower surfaces (contact surfaces) of all the first cells 1A. The lower surface of the first heat diffusion sheet 3A is in surface contact with the upper surfaces (contact surfaces) of all the second cells 1B. The upper surface of the second heat diffusion sheet 3B is in surface contact with the lower surfaces (contact surfaces) of all the second cells 1B. The lower surface of the second heat diffusion sheet 3B is in surface contact with the upper surfaces (contact surfaces) of all the third single cells 1C.

The thermal diffusion sheet 3 has a thermal conductivity higher than the thermal conductivity of the contact surface of the unit cell 1. Thus, the thermal diffusion sheet 3 can diffuse the heat generated in the unit cell 1 in the in-plane direction.

Since the battery pack 10C shown in FIG. 6 includes the thermal diffusion sheet 3 whose thermal conductivity is higher than the contact surface of the unit cell 1, the heat generated by the unit cell 1 is diffused by the thermal diffusion sheet 3, The temperature difference between the cells 1 can be reduced, and the temperature uniformity among the cells 1 can be maintained.

FIG. 7 is a perspective view schematically showing a battery pack 10D of another embodiment. As shown in FIG. 7, the assembled battery 10D includes the unit cell 1, the battery case 2, the thermal diffusion sheet 3, the pair of protection plates 304, the pair of packings 305, and the holding portion 306.

The packing 305 is formed in a sheet shape along the XZ plane. The packing 305 abuts on both ends of the cylindrical portion 14 and closes the openings at both ends of the cylindrical portion 14. The protective plate 304 is formed in a plate shape along the XZ plane. The protective plate 304 is provided on the outer surface side of the packing 305. The protective plate 304 closes the openings at both ends of the cylindrical portion 14 via the packing 305. The holding portion 306 is formed in a cylindrical shape, and holds the battery exterior body 2 and the heat diffusion sheet 3 inside.

In the assembled battery 10D shown in FIG. 7, the opening of the cylindrical portion 14 can be closed by the protective plate 304 and the packing 305, so the sealing performance of the battery exterior body 2 can be enhanced. By enhancing the sealability of the battery outer package 2, the physical strength of the assembled battery 10D can be improved.

FIG. 8 is a view schematically showing an example of a motor-driven device using the battery pack 10. As shown in FIG. The electrically powered device 400 is a vehicle movable by the drive mechanism 401. The electrically powered device 400 includes a vehicle body 402 and four wheels 403. The drive mechanism 401 is a motor or the like that operates by power feeding from the assembled battery 10, and drives at least a part of the four wheels 403. The vehicle body 402 mounts the drive mechanism 401 and the battery assembly 10. The vehicle body 402 may further include a cooling device such as a cooling fan for sending air or the like to the assembled battery 10 for cooling, and may be driven by the assembled battery 10. As an electrically-driven apparatus, not only a vehicle but airplanes, such as an escalator, a washing machine, a refrigerator, a drone, a ship, a machine tool, etc. can be illustrated.

The present invention is not limited to the embodiments described above, and various modifications are possible without departing from the scope of the present invention.
In the battery set shown in FIGS. 1 and 6, one heat diffusion sheet 3 is in direct or indirect contact with six unit cells 1 respectively, but the heat diffusion sheets are directly connected to two or more unit cells. Or it should just be in contact indirectly.
The unit cell 1 is not limited to a lithium ion battery, and may be an electric double layer capacitor, a nickel hydrogen battery, a nickel cadmium battery, a polymer lithium ion battery, a sodium ion battery, other secondary batteries and the like.
The heat diffusion sheet 3 is not limited to a graphite sheet, but may be a multilayer structure in which a graphite sheet and another layer are laminated. The thermal diffusion sheet 3 may be a sheet made of a carbon-based material other than graphite (for example, carbon nanotubes).

In the battery exterior body 2 shown in FIG. 1 and the like, the exterior plates 6 and 6 are each continuously formed in the width direction across the plurality of cylindrical portions 14, but the exterior plates are any of the facing exterior plates Only one side may be continuously formed in the width direction across the plurality of cylindrical portions, and the other exterior plate may be configured to be independent for each cylindrical portion.

Example 1
A battery assembly in which the cylindrical portion 14 had a hexagonal cylindrical shape (see FIG. 1) was manufactured as follows. Seven sets of exterior plates 6, 6 constituting the battery exterior body 2 were manufactured. The battery exterior body 2 has three battery accommodating portions 15 arranged in the X direction. A structure in which three cylindrical portions 14 are arranged in the X direction and seven cylindrical portions 14 are arranged in the Z direction by alternately stacking the battery outer package 2 and the graphite sheet 3 (thickness 200 μm) (thermal diffusion sheet 3) The body was made. A total of 21 flat type single cells 1 were placed in each cylindrical portion 14 to make electrical connection.

The three unit cells 1 arranged in the X direction were connected with wires so as to conduct in parallel, and the plurality of battery groups arranged in the Z direction were connected with wires so as to conduct in series. The unit cell 1 is a lithium ion battery. The container of the unit cell 1 is a laminate of resin layer / metal layer / resin layer. The protective plate 4 was disposed at the end of the resulting structure consisting of the battery outer package 2 and the graphite sheet 3, and these protective plates 4 were fixed by bolts 5A and nuts 5B.

Thermocouples 21 were disposed in contact with the surface of each unit cell 1 in the cylindrical portion 14, and the temperature of each unit cell at the time of discharge was measured. The change in battery temperature was plotted over time. The graph which plotted simultaneously the temperature change of the cell with the highest temperature, the temperature change of the cell with the lowest temperature, and the temperature change of the cell of those intermediate temperature is shown in FIG.

FIG. 11 is a diagram in which the temperature difference between the hottest cell and the coldest cell is plotted. Among the unit cells after one hour, the highest temperature was the unit cell (central unit cell) at the center of the assembled battery, and the temperature was 48.3 ° C. Among the unit cells after one hour, the lowest temperature was the unit cell at the end (the four corners of both sides) of the assembled battery, and the temperature was 43.8 ° C. The difference between the high and low temperatures of the unit cell was 4.5.degree.

(Comparative example 1)
A battery assembly was manufactured in the same manner as in Example 1 except that the graphite sheet was removed. Thermocouples 21 were disposed in contact with the surface of each unit cell in the cylindrical portion of the assembled battery, and the temperature of each unit cell at the time of discharge was measured. The change in temperature of each unit cell during discharge was plotted with time. The graph which plotted simultaneously the temperature change of the cell with the highest temperature, the temperature change of the cell with the lowest temperature, and the temperature change of the cell of those intermediate temperature is shown in FIG.

The temperature difference between the hottest cell and the coldest cell is also shown in FIG. Among the unit cells after one hour, the highest temperature was the unit cell (central unit cell) at the center of the assembled battery, and the temperature was 49.3 ° C. Among the unit cells after one hour, the lowest temperature was the unit cell at the end (the four corners of both sides) of the assembled battery, and the temperature was 38.8 ° C. The difference between the high and low points of the cell temperature was 10.5 ° C.

By comparing Example 1 and Comparative Example 1, it can be seen that in Example 1 using a graphite sheet, the temperature difference between the battery with the highest temperature and the battery with the lowest temperature is reduced.

According to the present invention, since the temperature difference between the unit cells can be reduced in the assembled battery, industrial use is possible.

1, 1A, 1B, 1C ... cell, 2, 2A, 2B, 2C, 102A, 102B, 102C, 202A, 202B, 202C ... battery outer package, 3, 3A, 3B ... thermal diffusion sheet, 4, 304 ... protection Plates 6, 6A to 6F, 106A to 106F, 206: Outer plate, 7, 107: contact portion, 14, 114: cylindrical portion, 10, 10A, 10B, 10C, 10D: assembled battery, 50: battery body , 51: container, 57: metal layer, 58: resin layer, 400: electric device, 401: drive mechanism.

Claims (8)

With multiple cells,
A thermal diffusion sheet in direct or indirect contact with two or more of the plurality of unit cells,
The assembled battery, wherein the heat diffusion sheet has a thermal conductivity higher than that of the contact surface of the unit cell. The battery pack further includes a battery outer body that covers the unit cell.
The battery case is interposed between the unit cell and the heat diffusion sheet and is in contact with the heat diffusion sheet.
The assembled battery according to claim 1, wherein the heat diffusion sheet has a thermal conductivity higher than the thermal conductivity of the contact surface of the battery outer package instead of the contact surface of the unit cell. The assembled battery according to claim 1, wherein the heat diffusion sheet is made of graphite. Has a stacked structure in which a plurality of layers formed of the two or more unit cells are stacked,
The assembled battery according to any one of claims 1 to 3, wherein the heat diffusion sheet is provided between the plurality of layers. The battery case includes at least a pair of facing plates.
The exterior plates abut each other at a plurality of abutment portions at intervals in the width direction,
The assembled battery according to claim 2, wherein the unit cells are respectively accommodated in a plurality of cylindrical portions partitioned by the contact portion. The assembled battery according to claim 5, wherein a protection plate for closing the opening of the cylindrical portion is provided on one side and the other side of the cylindrical portion. The unit cell includes a battery body, and a container having an internal space for housing the battery body,
The assembled battery according to any one of claims 1 to 6, wherein the container is formed of a laminated body in which a metal layer and a resin layer are laminated, and the resin layer is on the side of the internal space. An assembled battery according to any one of claims 1 to 7;
And a drive mechanism driven by the assembled battery.

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