阅读说明：本技术 电源装置和使用该电源装置的电动车辆以及蓄电装置、电源装置用紧固构件、电源装置的制造方法、电源装置用紧固构件的制造方法 (Power supply device, electrically powered vehicle using same, power storage device, fastening member for power supply device, method for manufacturing power supply device, and method for manufacturing) 是由 山城豪 于 2019-12-24 设计创作，主要内容包括：为了提供一种提高层叠多片二次电池单体而成的电池层叠体的紧固的强度并且也确保该紧固的拉伸性的电源装置等,电源装置具有：多个二次电池单体,该多个二次电池单体的外装罐设为方形；一对端板,该一对端板将层叠多个二次电池单体而成的电池层叠体的两侧端面覆盖；以及金属制的多个紧固构件(15),该多个紧固构件是沿着多个二次电池单体的层叠方向延长的板状并且分别配置于电池层叠体的相对的侧面从而对端板彼此进行紧固,其中,构成为,多个紧固构件(15)分别具有在长度方向上的两端分别与端板固定的紧固部分(15c)以及将紧固部分(15c)彼此之间连结的中间部分(15a),紧固部分(15c)的强度比中间部分(15a)的强度高,中间部分(15a)的拉伸性比紧固部分(15c)的拉伸性高。(In order to provide a power supply device or the like that increases the strength of fastening a battery laminate formed by laminating a plurality of secondary battery cells and also ensures the stretchability of the fastening, the power supply device includes: a plurality of secondary battery cells, the outer cans of which are formed in a square shape; a pair of end plates that cover both end surfaces of a battery stack formed by stacking a plurality of secondary battery cells; and a plurality of metal fastening members (15) that are plate-shaped and extend in the stacking direction of the plurality of secondary battery cells, and that are respectively disposed on opposite side surfaces of the battery stack to fasten the end plates to each other, wherein the plurality of fastening members (15) each have a fastening portion (15c) that is fixed to the end plate at each end in the longitudinal direction, and an intermediate portion (15a) that connects the fastening portions (15c) to each other, the fastening portion (15c) has a higher strength than the intermediate portion (15a), and the intermediate portion (15a) has a higher tensile strength than the fastening portion (15 c).)

1. A power supply device includes: a plurality of secondary battery cells, the outer cans of which are formed in a square shape; a pair of end plates that cover both end surfaces of a battery stack formed by stacking the plurality of secondary battery cells; and a plurality of metal fastening members that are plate-shaped and extend in the stacking direction of the plurality of secondary battery cells, and that are respectively disposed on opposite side surfaces of the battery stack to fasten the end plates to each other, wherein the plurality of metal fastening members are configured,

the plurality of fastening members each have:

fastening portions, both ends of which in a length direction are fixed to the end plates, respectively; and

an intermediate portion that joins the fastening portions to each other,

the strength of the fastening portion is higher than the strength of the intermediate portion,

the intermediate portion has a higher stretchability than the fastening portion.

2. The power supply device according to claim 1,

the thickness of the fastening portion is formed to be thicker than the thickness of the intermediate portion.

3. The power supply device according to claim 2,

the fastening member further has a locking piece fixed to the fastening portion,

the end plate is formed with a step portion for locking the locking piece in a state of being fastened by the fastening member,

the fastening portion and the locking piece are fixed by welding.

4. The power supply device according to any one of claims 1 to 3, wherein the power supply device is configured to,

the fastening portion is constructed of a first metal,

the intermediate portion is composed of a second metal different from the first metal,

the first metal has a higher strength than the second metal,

the second metal has a higher stretchability than the first metal.

5. The power supply device according to any one of claims 1 to 4,

the surfaces of the plurality of fastening members that cover the side surfaces of the battery stack are formed in the same plane at the joints of the fastening portions and the intermediate portions.

6. The power supply device according to any one of claims 1 to 5,

the fastening member is composed of a differential thickness material.

7. The power supply device according to any one of claims 1 to 6,

the joining interface of the fastening portion and the intermediate portion of the fastening member is joined by welding.

8. An electric vehicle having the power supply device according to any one of claims 1 to 7,

the electric vehicle includes:

the power supply device;

a motor for traveling, to which electric power is supplied from the power supply device;

a vehicle body on which the power supply device and the motor are mounted; and

and wheels that are driven by the electric motor to run the vehicle body.

9. An electric storage device having the power supply device according to any one of claims 1 to 7,

the power storage device includes:

the power supply device; and

a power supply controller for controlling charging and discharging of the power supply device,

the secondary battery cell can be charged with electric power from the outside by the power supply controller, and is controlled by the power supply controller so as to be charged.

10. A fastening member for a power supply device for fastening a pair of end plates to each other, the pair of end plates covering both end surfaces of a battery stack formed by stacking a plurality of secondary battery cells each having a rectangular outer can, wherein the fastening member is configured to,

the fastening member for a power supply device includes:

fastening portions, both ends of which in a length direction are fixed to the end plates, respectively; and

an intermediate portion that joins the fastening portions to each other,

the strength of the fastening portion is higher than the strength of the intermediate portion,

the intermediate portion has a higher stretchability than the fastening portion.

11. A method for manufacturing a fastening member for a power supply device for fastening a pair of end plates that cover both side end surfaces of a battery stack formed by stacking a plurality of secondary battery cells each having a rectangular outer can to each other,

the method for manufacturing the fastening member for the power supply device comprises the following steps:

preparing a fastening portion having both ends in a longitudinal direction fixed to the end plates, respectively, and an intermediate portion connecting the fastening portions to each other; and

and a step of joining the fastening portion and the intermediate portion by welding.

12. A method for manufacturing a power supply device, the power supply device comprising: a plurality of secondary battery cells, the outer cans of which are formed in a square shape; a pair of end plates that cover both end surfaces of a battery stack formed by stacking the plurality of secondary battery cells; and a plurality of metal fastening members that are plate-shaped and extend in the stacking direction of the plurality of secondary battery cells, and that are respectively disposed on opposite side surfaces of the battery stack to fasten the end plates to each other,

the method for manufacturing the power supply device comprises the following steps:

a step of joining, by welding, fastening portions each having both ends in a longitudinal direction fixed to the end plate and an intermediate portion connecting the fastening portions to each other; and

and covering both end surfaces of the battery stack with the pair of end plates and fastening the end plates to each other with a power supply device fastening member.

Technical Field

The present invention relates to a power supply device, an electrically powered vehicle and a power storage device using the power supply device, a fastening member for a power supply device, a method for manufacturing a power supply device, and a method for manufacturing a fastening member for a power supply device.

Background

The power supply device is used for a power supply device for driving an electric vehicle, a power supply device for storing electricity, and the like. In such a power supply device, a plurality of rechargeable and dischargeable secondary battery cells are stacked. In general, as shown in the perspective view of fig. 8, in the power supply device 900, end plates 903 are disposed on both side end surfaces of a battery laminate in which rectangular outer-can secondary battery cells 901 are laminated, and the end plates 903 are fastened to each other by a metal tightening strip 904.

The exterior can expands and contracts when the secondary battery cell is repeatedly charged and discharged. In particular, with the recent demand for higher capacity, the capacity of the single secondary battery cell has been increased, and as a result, the amount of swelling also tends to increase. In a battery laminate in which a plurality of such secondary battery cells are stacked and fastened, a strong load is applied when the battery laminate swells. As a result, it is considered that a strong shear stress acts on the joint portion between the tightening strip and the end plate, and the joint portion is broken. Therefore, it is required to improve the strength of the fastening strip.

However, generally, the stretchability of a metal material is reduced when the strength thereof is increased. When the secondary battery cell expands, a load is applied in the direction in which the tightening strip extends, but if the stretchability decreases, there is a problem that the resistance to expansion decreases.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 9-120808

Disclosure of Invention

Problems to be solved by the invention

An object of the present invention is to provide a power supply device capable of improving the fastening strength of a battery laminate formed by laminating a plurality of secondary battery cells and also capable of ensuring the stretchability of the fastening, an electric vehicle and an electric storage device using the power supply device, a fastening member for the power supply device, a method for manufacturing the power supply device, and a method for manufacturing the fastening member for the power supply device.

Means for solving the problems

A power supply device according to one aspect of the present invention includes: a plurality of secondary battery cells, the outer cans of which are formed in a square shape; a pair of end plates that cover both end surfaces of a battery stack formed by stacking the plurality of secondary battery cells; and a plurality of metal fastening members that are plate-shaped and extend in a stacking direction of the plurality of secondary battery cells, and that are respectively disposed on opposite side surfaces of the battery stack to fasten the end plates to each other, wherein each of the plurality of fastening members has a fastening portion that is fixed to each of the end plates at both ends in a longitudinal direction, and an intermediate portion that connects the fastening portions to each other, and the fastening portion has a higher strength than the intermediate portion, and the intermediate portion has a higher stretchability than the fastening portion.

An electrically powered vehicle according to an aspect of the present invention includes the power supply device, a traveling motor to which electric power is supplied from the power supply device, a vehicle body on which the power supply device and the motor are mounted, and wheels that are driven by the motor and run the vehicle body.

An electrical storage device according to an aspect of the present invention includes the power supply device described above, and a power supply controller that controls charging and discharging of the power supply device, and is capable of charging the secondary battery cell with electric power from outside by the power supply controller, and controlling so as to charge the secondary battery cell with the power supply controller.

In a power supply device fastening member according to one aspect of the present invention, which is used for fastening a pair of end plates that cover both end surfaces of a battery stack body formed by stacking a plurality of secondary battery cells each having a rectangular outer can, the power supply device fastening member has fastening portions that are fixed to the end plates at both ends in a longitudinal direction, respectively, and an intermediate portion made of a second metal that connects the fastening portions to each other, and is configured such that the strength of the fastening portions is higher than the strength of the intermediate portion, and the stretchability of the intermediate portion is higher than the stretchability of the fastening portions.

A method for manufacturing a fastening member for a power supply device according to an aspect of the present invention is a method for manufacturing a fastening member for a power supply device for fastening a pair of end plates that cover both side end surfaces of a battery stack body formed by stacking a plurality of secondary battery cells each having a rectangular outer can, the method including: preparing a fastening portion having both ends in a longitudinal direction fixed to the end plates, respectively, and an intermediate portion connecting the fastening portions to each other; and a step of joining the fastening portion and the intermediate portion by welding.

In a method for manufacturing a power supply device according to an aspect of the present invention, the power supply device includes: a plurality of secondary battery cells, the outer cans of which are formed in a square shape; a pair of end plates that cover both end surfaces of a battery stack formed by stacking the plurality of secondary battery cells; and a plurality of metal fastening members that are plate-shaped and extend in the stacking direction of the plurality of secondary battery cells, and that are respectively disposed on opposite side surfaces of the battery stack to fasten the end plates to each other, wherein the method for manufacturing the power supply device includes: a step of joining, by welding, fastening portions each having both ends in a longitudinal direction fixed to the end plate and an intermediate portion connecting the fastening portions to each other; and covering both end surfaces of the battery stack with a pair of end plates and fastening the end plates to each other with a power supply device fastening member.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the above power supply device, resistance to expansion of the secondary battery cell can be improved by increasing the strength of the fastening portion of the fastening member that fastens the battery laminate, and the opposite characteristics of strength and stretchability can be achieved by increasing the stretchability of the intermediate portion.

Drawings

Fig. 1 is a perspective view showing a power supply device according to embodiment 1.

Fig. 2 is an exploded perspective view of the power supply device of fig. 1.

Fig. 3 is a horizontal sectional view of the power supply device of fig. 1 taken along line III-III.

Fig. 4 is a perspective view showing the fastening member of fig. 2.

Fig. 5 is a perspective view of the fastening member of fig. 4 as viewed from the back.

Fig. 6 is an exploded perspective view of the fastening member of fig. 5.

Fig. 7A to 7C are schematic views showing a procedure for forming the fastening member by using the difference in thickness material.

Fig. 8 is an exploded perspective view showing a conventional power supply device.

Fig. 9 is an exploded perspective view showing a power supply device which has been developed by the applicant.

Fig. 10 is an enlarged cross-sectional view showing a bent portion of a fastening member of a conventional power supply device.

Fig. 11 is a horizontally enlarged sectional view taken along line XI-XI of fig. 4.

Fig. 12 is a horizontally enlarged sectional view of the fastening member of embodiment 2.

Fig. 13 is a block diagram showing an example of a power supply device mounted on a hybrid vehicle that travels using an engine and a motor.

Fig. 14 is a block diagram showing an example of a power supply device mounted on an electric vehicle that travels only by a motor.

Fig. 15 is a block diagram showing an example of a power supply device applied to power storage.

Detailed Description

The power supply device according to one embodiment of the present invention may be configured as follows, in addition to the above configuration.

In the power supply device according to the embodiment of the present invention, the thickness of the fastening portion is formed to be thicker than the thickness of the intermediate portion. According to the above configuration, the strength and the stretchability can be adjusted by varying the thickness of the metal fastening member.

In the power supply device according to another embodiment of the present invention, the fastening member further includes a locking block fixed to the fastening portion, the end plate has a stepped portion formed thereon for locking the locking block in a state of being fastened by the fastening member, and the fastening portion and the locking block are fixed by welding. According to the above configuration, sufficient welding strength can be exhibited by welding at the fastening portion having a large thickness, and stretchability can be ensured at the intermediate portion having a small thickness, so that deformation with respect to expansion of the secondary battery cell can be coped with, and strength and stretchability can be compatible.

In the power supply device according to another embodiment of the present invention, the fastening portion may be made of a first metal, the intermediate portion may be made of a second metal different from the first metal, the first metal may have a higher strength than the second metal, and the second metal may have a higher elongation than the first metal. According to the above configuration, the regions having respectively improved strength and stretchability can be formed by combining different kinds of metals.

In the power supply device according to the other embodiment of the present invention, the surfaces of the plurality of fastening members covering the side surfaces of the battery stack are formed in the same plane at the joint between the fastening portion and the intermediate portion.

In the power supply device according to another embodiment of the present invention, the fastening member is made of a different material. According to the above structure, the fastening portion and the intermediate portion can be constituted by different members.

Further, in the power supply device of another embodiment of the present invention, a joining interface of the fastening portion and the intermediate portion of the fastening member is joined by welding. According to the above configuration, metals can be joined to each other with higher reliability than spot welding or the like.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiments described below are examples for embodying the technical idea of the present invention, and the present invention is not limited to the embodiments described below. In addition, the present specification by no means limits the components shown in the claims to those of the embodiments. In particular, the dimensions, materials, shapes, relative arrangements, and the like of the constituent members described in the embodiments are not intended to limit the scope of the present invention to these values unless otherwise specified, but are merely illustrative examples. In addition, the sizes, positional relationships, and the like of the members shown in the drawings may be exaggerated for the sake of clarity. In the following description, the same names and reference numerals denote the same or substantially the same members, and detailed description thereof will be omitted as appropriate. Each element constituting the present invention may be configured such that a plurality of elements are constituted by the same member and one member is used as a plurality of elements, or conversely, a function of one member may be realized by being divided into a plurality of members. In addition, some of the contents described in some examples and embodiments may be used in other examples and embodiments.

The power supply device according to the embodiment is used in various applications such as a power supply that is mounted on an electric vehicle such as a hybrid vehicle or an electric vehicle and supplies electric power to a traveling motor, a power supply that accumulates generated power of natural energy such as solar power generation or wind power generation, or a power supply that accumulates midnight electric power, and can be used as a power supply suitable for an application of high electric power or large current in particular. In the following examples, embodiments applied to a power supply device for driving an electric vehicle will be described.

[ embodiment 1]

Fig. 1 shows a perspective view of a power supply device 100 according to embodiment 1 of the present invention, fig. 2 shows an exploded perspective view thereof, fig. 3 shows a horizontal cross-sectional view taken along line III-III of the power supply device 100 of fig. 1, fig. 4 shows a perspective view showing the fastening member 15 of fig. 2, fig. 5 shows a perspective view of the fastening member 15 of fig. 4 as viewed from the back, and fig. 6 shows an exploded perspective view of the fastening member 15 of fig. 5. The power supply device 100 shown in these figures includes a battery laminate 10 in which a plurality of secondary battery cells 1 are laminated, a pair of end plates 20 covering both end surfaces of the battery laminate 10, and a plurality of fastening members 15 fastening the end plates 20 to each other.

The battery laminate 10 includes: a plurality of secondary battery cells 1 having positive and negative electrode terminals 2; and a bus bar (not shown) connected to the electrode terminals 2 of the plurality of secondary battery cells 1 to connect the plurality of secondary battery cells 1 in parallel and in series. The plurality of secondary battery cells 1 are connected in parallel and in series via these bus bars. The secondary battery cell 1 is a secondary battery that can be charged and discharged. In the power supply device 100, a plurality of secondary battery cells 1 are connected in parallel to form a parallel battery pack, and a plurality of parallel battery packs are connected in series to connect a plurality of secondary battery cells 1 in parallel and in series. In the power supply device 100 shown in fig. 1 to 3, a plurality of secondary battery cells 1 are stacked to form a battery stack 10. A pair of end plates 20 are disposed on both end surfaces of the cell stack 10. The end portions of the fastening members 15 are fixed to the end plates 20, thereby fixing the secondary battery cells 1 in the stacked state in a pressurized state.

(Secondary Battery cell 1)

The secondary battery cell 1 is a rectangular battery having a rectangular main surface with a wide width, and has a thickness smaller than the width. The secondary battery cell 1 is a chargeable and dischargeable secondary battery, and is a lithium ion secondary battery. However, the secondary battery cell is not limited to the rectangular battery nor the lithium ion secondary battery in the present invention. As the secondary battery cell, any chargeable battery can be used, for example, a nonaqueous electrolyte secondary battery other than a lithium ion secondary battery, a nickel hydride secondary battery cell, and the like.

As shown in fig. 2, in the secondary battery cell 1, an electrode assembly formed by stacking positive and negative electrode plates is housed in an outer can 1a, filled with an electrolyte solution, and hermetically sealed. The outer can 1a is formed in a square tubular shape with a closed bottom, and an upper opening thereof is hermetically closed by a sealing plate 1b which is a metal plate. The outer can 1a is produced by deep drawing a metal plate of aluminum, aluminum alloy, or the like. The sealing plate 1b is made of a metal plate such as aluminum or aluminum alloy, as in the outer can 1 a. The sealing plate 1b is inserted into the opening of the outer can 1a, and laser beams are irradiated to the boundary between the outer periphery of the sealing plate 1b and the inner periphery of the outer can 1a to laser-weld the sealing plate 1b to the outer can 1a for airtight fixation.

(electrode terminal 2)

In the secondary battery cell 1, a sealing plate 1b serving as a top surface is a terminal surface 1X, and positive and negative electrode terminals 2 are fixed to both end portions of the terminal surface 1X. The protruding portion of the electrode terminal 2 is formed in a cylindrical shape. However, the protruding portion does not necessarily have to be cylindrical, and may be polygonal column-shaped or elliptical column-shaped.

The positive and negative electrode terminals 2 fixed to the sealing plate 1b of the secondary battery cell 1 are positioned such that the positive electrode and the negative electrode are bilaterally symmetrical. Thus, the adjacent secondary battery cells 1 can be connected in series by stacking the secondary battery cells 1 in a left-right reverse direction and connecting the adjacent positive and negative electrode terminals 2 with the bus bars.

(Battery laminate 10)

The battery stack 10 is configured by stacking a plurality of secondary battery cells 1 such that the thickness direction of each secondary battery cell 1 is the stacking direction. In the battery laminate 10, a plurality of secondary battery cells 1 are laminated such that terminal surfaces 1X provided with positive and negative electrode terminals 2, that is, sealing plates 1b in fig. 2, are flush with each other.

In the battery stack 10, the insulating separator 16 may be interposed between the secondary battery cells 1 stacked adjacent to each other. The insulating separator 16 is made of an insulating material such as resin and is formed in a thin plate shape or a sheet shape. The insulating separator 16 is formed in a plate shape having a size substantially equal to the opposing surface of the secondary battery cell 1. The insulating separator 16 is stacked between the adjacent secondary battery cells 1, thereby insulating the adjacent secondary battery cells 1 from each other. As the separator disposed between the adjacent secondary battery cells 1, a separator having a shape in which a flow path for the cooling gas is formed between the secondary battery cell 1 and the separator may be used. In addition, the surface of the secondary battery cell 1 may be covered with an insulating material. For example, the parts of the surface of the outer can of the secondary battery cell other than the electrode parts may be heat-welded by a shrink tube made of PET resin or the like. In this case, the insulating spacer may be omitted. In the power supply device in which a plurality of secondary battery cells are connected in parallel and a plurality of secondary battery cells are connected in series, the secondary battery cells connected in series are insulated from each other with an insulating separator interposed therebetween, and the adjacent exterior cans do not generate a voltage difference with respect to the secondary battery cells connected in parallel, so that the insulating separator between the secondary battery cells can be omitted.

In the power supply device 100 shown in fig. 2, end plates 20 are disposed on both end surfaces of the battery stack 10. The end separator 17 may be interposed between the end plate 20 and the cell stack 10 to insulate them. The end-face separator 17 may be made of an insulating material such as resin and may be formed in a thin plate shape or a sheet shape.

In the battery stack 10, a metal bus bar is connected to the positive and negative electrode terminals 2 of the adjacent secondary battery cells 1, and the plurality of secondary battery cells 1 are connected in parallel and in series via the bus bar. In the battery stack 10, the plurality of secondary battery cells 1 connected in parallel with each other to form a parallel battery assembly are stacked such that the positive and negative electrode terminals 2 provided at both end portions of the terminal surface 1X are oriented in the same direction in the left-right direction, and the plurality of secondary battery cells 1 connected in series with each other to form a parallel battery assembly are stacked such that the positive and negative electrode terminals 2 provided at both end portions of the terminal surface 1X are oriented in the opposite direction in the left-right direction. However, the present invention is not limited to the number of secondary battery cells constituting the battery stack and the connection state thereof. The number of secondary battery cells constituting the battery stack and the connection state thereof may be variously changed including other embodiments described later.

In the power supply device 100 of the embodiment, in the battery stack 10 in which the plurality of secondary battery cells 1 are stacked on each other, the electrode terminals 2 of the plurality of secondary battery cells 1 adjacent to each other are connected to each other by the bus bar, and the plurality of secondary battery cells 1 are connected in parallel and in series. Further, a bus bar holder may be disposed between the battery stack 10 and the bus bar. By using the bus bar holder, the plurality of bus bars can be insulated from each other and the terminal surfaces of the secondary battery cells can be insulated from the bus bars, and the plurality of bus bars can be arranged at fixed positions on the upper surface of the battery stack.

(bus bar)

The bus bar is manufactured into a predetermined shape by cutting and processing a metal plate. As the metal plate constituting the bus bar, a metal having a small electric resistance and a light weight, for example, an aluminum plate, a copper plate, or an alloy thereof can be used. However, other metals having a small electric resistance and a light weight, and alloys thereof can be used for the metal plate of the bus bar.

(end plate 20)

As shown in fig. 1 to 3, the end plates 20 are disposed at both ends of the cell stack 10 and are fastened by a pair of left and right fastening members 15 disposed along both side surfaces of the cell stack 10. The end plates 20 are disposed at both ends of the battery stack 10 in the stacking direction of the secondary battery cells 1 and outside the end face separators 17, sandwiching the battery stack 10 from both ends.

(step part 20b)

The end plate 20 has a stepped portion 20b, and the stepped portion 20b is used to lock the locking piece 15b provided in the fastener 15 in a state where the end plate 20 is fastened to the fastener 15. The stepped portion 20b is formed in a size and shape capable of locking a locking piece 15b of the fastener member 15 described later. In the example of fig. 2, a flange-like stepped portion 20b is formed so that the end plate 20 becomes a letter T shape in a horizontal cross-sectional view. In addition, an end plate screw hole 20c is opened in the vicinity of the stepped portion 20 b.

(fastening member 15)

Both ends of the fastening member 15 are fixed to end plates 20 disposed on both end surfaces of the cell stack 10. The end plates 20 are fixed by a plurality of fastening members 15, thereby fastening the cell stack 10 in the stacking direction. As shown in fig. 4, 5, 6, and the like, each fastening member 15 is a metal plate having a predetermined width and a predetermined thickness along the side surface of the cell laminate 10, and is disposed so as to face both side surfaces of the cell laminate 10.

The fastening member 15 is composed of fastening portions 15c fixed to the end plates 20 at both ends in the longitudinal direction, respectively, and an intermediate portion 15a connecting the fastening portions 15c to each other. Here, the strength of the fastening portion 15c is made higher than the strength of the intermediate portion 15a, and the stretchability of the intermediate portion 15a is made higher than the stretchability of the fastening portion 15 c. As a result, the fastening portion 15c is increased in strength to exert the fastening force of the battery laminate, and the intermediate portion 15a is increased in stretchability to be easily deformed when the secondary battery cell 1 expands, so that the opposite characteristics of strength and stretchability can be satisfied.

(differential thickness Material)

Preferably, in the fastening member 15, the fastening portion 15c and the intermediate portion 15a are constituted by a differential thickness material. The difference thickness material is a material formed in a shape having a locally different thickness. Specifically, the material is obtained by joining a plurality of steel plates (blanks) having different plate thicknesses. As a joining method, various methods such as welding such as laser welding and MIG welding, friction pressure welding, electromagnetic pressure welding, pressure welding by ultrasonic joining, laser brazing, and brazing such as MIG brazing can be used. The difference-thickness material may be formed by partially rolling a single steel plate (blank) or by continuously forging the steel plate (Japanese: successive article of footwear). Thus, the fastening portion 15c and the intermediate portion 15a can be formed of different members, and a member having high strength can be assigned to the fastening portion 15c and a member having high stretchability can be assigned to the intermediate portion 15a, respectively, so that a fastening member 15 having both strength and stretchability, which has been difficult to achieve in the past, can be obtained. Hereinafter, a structure in which a plurality of steel plates (blanks) having different plate thicknesses are laser-welded to form the fastening member 15 will be described as an example.

The joint interface of the fastening portion 15c and the intermediate portion 15a is welded by laser welding. As shown in fig. 7A, the fastening member 15 is obtained by welding a metal plate (blank) having a constant material thickness, that is, a fastening portion 15C and an intermediate portion 15a in a state of being developed as shown in fig. 7B, in a state of being joined as shown in fig. 7C. Among these welding, as shown in fig. 7B in particular, it is preferable to perform welding in a continuous linear shape. The structure in which welding is performed in a continuous line shape has a feature that the connection strength of the plurality of metal plates can be improved. Specifically, the welding is performed along the joint interface of the fastening portion 15c and the intermediate portion 15 a. As a result, as shown in the perspective view of fig. 4, a weld 15g is formed between the fastening portion 15c and the intermediate portion 15 a. Such welding enables metals to be joined to each other with higher reliability than spot welding or the like.

The fastening member 15 can be made of a metal plate such as iron, and preferably can be made of a steel plate, iron, an iron alloy, SUS, aluminum, an aluminum alloy, or the like.

As shown in fig. 5, the surface of the fastening member 15 covering the side surface of the cell laminate 10 is preferably formed in the same plane in the joining of the fastening portion 15c and the intermediate portion 15 a. Thus, even if the fastening member 15 is constituted by a plurality of members, the side surface of the battery laminate 10 can be covered with a flat surface.

As shown in fig. 7B, the fastening member 15 is formed into a predetermined shape by press forming after welding in a step of joining the fastening portion 15c and the intermediate portion 15 a. In the fastening member 15 shown in fig. 7C, the upper and lower end edges are bent to form bent pieces 15 d. The upper and lower bent pieces 15d are shaped to cover the upper and lower surfaces of the battery laminate 10 from the corner portions on both the left and right side surfaces of the battery laminate 10.

(locking block 15b)

Fig. 6 shows an exploded perspective view of the fastening member 15. The fastening member 15 shown in the figure has an intermediate portion 15a, a fastening portion 15c, and a block-shaped locking piece 15 b. The intermediate portion 15a is a plate-like member, and fastening portions 15c are joined to both ends in the longitudinal direction thereof. The locking piece 15b is fixed to an inner surface of an end edge portion of the fastening portion 15 c. The locking block 15b is a plate having a predetermined thickness, and is fixed in a posture projecting inward of the fastening portion 15c, and in a state where the fastening member 15 is coupled to the end plate 20, the locking block 15b is locked to the step portion 20b provided in the end plate 20, and the fastening member 15 is arranged at a fixed position on both sides of the cell stack 10. The locking piece 15b is fixed to the fastening portion 15c by welding such as spot welding, laser welding, or the like.

The locking piece 15b shown in the figure is opened with a fastening-side through hole 15bc so that the fastening-side through hole 15bc coincides with the end plate screw hole 20c in a state where the end plate 20 is fastened. In addition, the fastening portion 15c has a fastening main surface side through hole 15ac opened at a position corresponding to the fastening side through hole 15 bc. The fastening-side through hole 15bc and the fastening-main-surface-side through hole 15ac are designed to coincide in a state where the locking piece 15b is fixed to the fastening portion 15 c.

A plurality of fastening-side through holes 15bc provided in the locking block 15b are opened along the extending direction of the locking block 15 b. Similarly, the fastening main surface side through holes 15ac are also opened in plural along the end edge of the fastening portion 15c or the extending direction of the locking piece 15 b. Accordingly, a plurality of end plate screw holes 20c are also formed along the side surface of the end plate 20.

The locking piece 15b is fixed to the outer peripheral surface of the end plate 20 by a plurality of bolts 15 f. The fastening of the fastening member 15, the locking piece 15b, and the end plate 20 is not necessarily limited to the screw connection using a bolt, and a pin, a rivet, or the like may be used.

As described above, iron alloy, SUS, aluminum alloy, or the like can be used for the intermediate portion 15a, the fastening portion 15c, and the locking piece 15b constituting the fastening member 15. The width of the locking piece 15b in the lateral direction in the cell stacking direction can be set to 10mm or more. The end plate 20 may be made of metal. Preferably, the locking piece 15b and the fastening portion 15c are made of the same metal. Thereby, the welding of the locking piece 15b and the fastening portion 15c can be easily performed.

As described above, the fastening member 15 is not bent at the left and right end portions in the longitudinal direction, that is, both end portions in the laminated layer direction of the battery stack 10 and screwed from the main surface side of the end plate 20, but as shown in fig. 1 to 3, the fastening member 15 is formed into a flat plate shape in the laminated layer direction of the battery stack 10 without providing a bent portion, and the battery stack 10 is fastened by the engagement structure and the screwing by the step portion 20b of the end plate 20 and the engagement piece 15b, whereby the strength can be improved, and the risk of breakage or the like due to expansion of the secondary battery cell 1 can be alleviated.

In a power supply device in which a plurality of secondary battery cells 1 are stacked, the plurality of secondary battery cells 1 are restrained by connecting end plates 20 disposed at both ends of a battery stack 10 composed of the plurality of secondary battery cells 1 with fastening members 15. By restraining the plurality of secondary battery cells 1 by the end plates 20 and the fastening members 15 having high strength, it is possible to suppress failures and the like caused by expansion, deformation, relative movement, and vibration of the secondary battery cells 1 accompanying charge and discharge and degradation.

On the other hand, in a conventional power supply device in which both ends of a battery stack are fixed by end plates, an L-shaped portion of a binding bar constituting a fastening member, which is bent inward at an end portion thereof, is fixed to an outer side surface of the end plate. For example, in a power supply device 900 shown in an exploded perspective view in fig. 8, a plurality of rectangular secondary battery cells 901 are stacked with separators 902 interposed therebetween, and end plates 903 are disposed on end faces and fastened by tie bars 904. The spacer 902 is made of hard resin or the like. As shown in the figure, the structure is as follows: both end edges of the binding bar 904 are bent to form a letter L shape, and the letter L-shaped portion 904b is fixed to the main surface side of the end plate 903 by a bolt 906.

In such a structure, the end portion of the tightening strip 904 of the metal plate is bent in the shape of the letter L to form a letter L-shaped portion, and the letter L-shaped portion is fixed to the outer surface of the end plate 903, so that the letter L-shaped portion is a metal plate having the same thickness as the tightening strip 904. As the tightening strip 904, a metal plate having a tensile strength capable of withstanding the tensile force generated by the expansion force of the secondary battery cell 901 is used. The tensile strength of the metal plate is considerably higher than the bending strength, and for example, a metal plate of about 1mm to 2mm is used as the tightening strip 904. The L-letter shaped portion fixed to the outer surface of the end plate 903 is subjected to bending stress by tensile force of the tightening strip 904, but the bending stress of the metal plate used for the end plate 903 is considerably weaker than the tensile stress, and the bent portion of the L-letter shaped portion is deformed and broken beyond the yield strength and breaking strength by the bending stress applied to the L-letter shaped portion. If there is no gap between the bent portion of the L-letter portion and the end plate 903, the inner side surface of the bent portion comes into contact with the corner of the end plate 903, and assembly becomes impossible.

Thus, an increase in the tensile force applied to the fastening strips leads to the following: strong stress is further locally concentrated on the inner side of the bent portion of the tightening strip and the corner portion of the end plate, and the tightening strip and the end plate are deformed or damaged. Accordingly, the applicant developed a power supply apparatus 800 shown in fig. 9. The power supply apparatus 800 includes a battery stack 810 in which a plurality of secondary battery cells 801 are stacked, a pair of end plates 820 disposed at both ends of the battery stack 810 in the stacking direction, and a fastening member 815 having both ends connected to the pair of end plates 820. The fastening member 815 has a fastening main surface 815a extending in the stacking direction of the cell stack 810, and a locking block 815b provided on the fastening main surface 815a and protruding toward an opposing surface opposing the outer peripheral surface of the end plate 820. The locking block 815b is fixed to the inner circumferential surface of the fixing hole 815g in a state of being inserted into the fixing hole 815g provided in the fastening main surface 815 a. The end plate 820 has a fitting portion 820c on the outer peripheral surface thereof for guiding the locking block 815b, and a protruding stepped portion is provided on the cell stack 810 side of the fitting portion 820c as a stopper portion 820b to be engaged with the locking block 815 b. In the power supply apparatus 800, the locking block 815b is guided to the fitting portion 820c, and the locking block 815b is fixed to the outer peripheral surface of the end plate 820.

In the power supply device having this structure, since the locking block is guided to the fitting portion and the positional deviation is prevented by the stopper portion, and the locking block is fixed to the end plate, the fastening member can be fixed to the end plate without being deformed by bending stress unlike the L-shaped portion of the conventional fastening member, and without being deformed by the locking block and the stopper portion. In particular, since the stopper portion guides the locking block to the fitting portion of the end plate and the positional shift is blocked by the stopper portion, the fastening member and the end plate can be prevented from being deformed by a strong tensile force acting on the fastening member, and the movement of the end plate can be suppressed.

The fastening member is applied with a strong tensile force as a reaction to the expansion force of the secondary battery cell, but in the conventional power supply device 900, the tensile force of the tightening strip 904 constituting the fastening member is applied as a bending stress at the bending portion and is deformed. In fig. 10, when the tightening strip 904 is deformed by the bending stress, the inner surface of the L-letter shaped portion 904b as the bent portion comes into close contact with the corner 903a of the end plate 903, and the tightening strip 904 is substantially stretched. In this state, the material may be broken beyond the yield strength or strength.

In contrast, in the power supply device having the structure of fig. 9, the locking block 815b provided in the fastening member 815 is guided to the fitting portion 820c of the end plate 820, and the stopper portion 820b prevents the locking block 815b guided thereto from being displaced. In the fastening member 815 fixed to the end plate 820 in this structure, even if there is a gap between the locking piece 815b and the end plate 820, the shear stress of the fastening member 815 is supported by a structure in which the locking piece 815b is guided to the fitting portion 820c and the locking piece 815b is arranged at a fixed position by the stopper portion 820b, without supporting the bending stress of the L-letter portion as in the conventional art. The fastening member 815 has a strength against shear stress that is considerably higher than that against tensile stress, and is not deformed by a strong tensile force acting on the fastening member 815, and can suppress movement of the end plate 820.

On the other hand, in the fastening member composed of the fastening main surface and the locking piece, it is necessary to fix the fastening main surface and the locking piece. Generally, the fastening main surface and the locking piece made of a metal member are often welded and fixed by spot welding with a laser. In this case, a certain thickness is required for spot welding of the metal member. Here, if the metal plate of the fastening main surface is made thick, the strength is increased, and as a result, the stretchability is reduced. The fastening member is required to be able to follow deformation of the secondary battery cell when it expands, but the metal plate is generally low in elasticity, and is higher in strength as the thickness thereof increases, and is more difficult to deform. However, if the fastening main surface is formed to be thin, the strength of spot welding with the locking piece is reduced, and the reliability of the fastening strength is reduced. In this way, since the requirements of strength and stretchability required for the fastening member are contradictory, it is difficult to achieve a compromise.

Therefore, in the present embodiment, the fastening member 15 is constituted by a member which is locally different, and the strength and the stretchability are successfully achieved at the same time. Specifically, as described above, the fastening member 15 is divided into the fastening portion 15c and the intermediate portion 15 a. Also, the fastening portion 15c is formed to a thickness t2 thicker than the thickness t1 of the intermediate portion 15 a. As a result, a sufficient thickness necessary for spot welding can be secured in the fastening portion 15c, and the joining strength with the locking piece 15b can be exhibited. On the other hand, the thickness t1 of the intermediate portion 15a is made thin, and the intermediate portion 15a is deformed when the secondary battery cell 1 expands, thereby ensuring the following property.

As shown in the horizontal sectional view of fig. 11, the thickness t2 of the fastening portion 15c is made larger toward the outside of the fastening member 15 than the thickness t1 of the intermediate portion 15a with respect to the thickness of the fastening member 15. In addition, the interface between the fastening portion 15c and the intermediate portion 15a is made to be the same plane on the inner side of the fastening member 15, i.e., the side facing the cell stack 10. On the other hand, in the portion of the fastening member 15 to which the thickness t3 of the locking piece 15b is fixed, the locking piece 15b is made to protrude inward with the outer side of the fastening member 15 being flush with the inner side. This allows the locking piece 15b to be locked to the stepped portion 20b of the end plate 20, thereby improving resistance to shear stress, and also preventing the fastening portion 15c from being thick and affecting the cell stack 10.

A position where the locking piece 15b is spot-welded to the fastening member 15, that is, a fixing region 15h where the locking piece 15b is fixed to the fastening member 15 is provided between the fastening-side through holes 15 bc. The fixing region 15h may be offset inward in the stacking direction of the secondary battery cells 1, that is, toward the middle portion 15 a. By arranging the fixing region 15h in a direction farther from the end plate 20 than the fastening-side through hole 15bc in this way, the distance between the fastening-side through hole 15bc, which opens to the locking piece 15b, and the fixing region 15h can be increased, and the concentration of stress can be alleviated. Further, by positioning the fixing region 15h not on the first straight line L1 connecting the centers of the fastening main surface side through holes 15ac as screw holes but on the second straight line L2 shifted from the first straight line L1, the area for spot welding can be secured large. Since the fastening main surface side through hole 15ac is circular, it is easy to secure a large area by shifting the fixing region 15h, and the area of spot welding can be increased, and as a result, the bonding strength of welding can be improved.

Preferably, the direction in which the fixing region 15h is offset from the first straight line L1 is a direction away from both end edges of the fastening member 15 and a direction toward the stepped portion 20b provided in the end plate 20. In the example of the exploded perspective view shown in fig. 6, the plurality of fixing regions 15h are offset toward the center of the cell stack 10. This allows the fixing regions 15h to receive the stress generated when the secondary battery cell 1 expands, thereby contributing to the dispersion of the applied stress and enhancing the strength of the fastening member 15.

As described above, according to the power supply device 100 of the present embodiment, the stress that is generated by the expansion of the secondary battery cell 1 and is intended to spread in the battery stacking direction is applied to the members, which are engaged by the step portion 20b and the locking piece 15b, welded by the fastening portion 15c and the locking piece 15b, and screwed by the bolt 15f, in addition to the fastening portion 15c itself. Therefore, by increasing the strength of each member and appropriately dispersing the stress, the overall strength can be increased, and the power supply device 100 can cope with the expansion and contraction of the secondary battery cell 1.

[ embodiment 2]

In the above example, the example in which the locking piece is joined by spot welding has been described, but the present invention is not limited to this configuration, and the fastening member having the locking piece may be formed by using a different-thickness material. Such an example is shown as embodiment 2 in a horizontal sectional view in fig. 12. In the fastening member 15 'shown in the figure, one end face of the intermediate portion 15a and one end face of the fastening portion 15 c' are joined, and a locking piece 15b 'is further joined to the other end face of the fastening portion 15 c'. The locking piece 15 b' is formed in advance to have a thickness t 3. In addition, the fastening portion 15c 'is formed narrower by the width of the locking piece 15 b' than the example of fig. 11. In this method, the intermediate portion 15a, the fastening portion 15c ', and the locking piece 15 b' can be joined together by welding, and therefore, there is an advantage that the manufacturing process can be simplified.

The above power supply device can be used as a power supply for a vehicle that supplies electric power to a motor that runs an electric vehicle. As an electric vehicle equipped with a power supply device, an electric vehicle such as a hybrid vehicle that runs using both an engine and a motor, a plug-in hybrid vehicle, or an electric vehicle that runs using only a motor can be used, and the above power supply device can be used as a power supply for the vehicle. An example in which a power supply device 100 having a large capacity and a high output is constructed in which a large number of the above-described power supply devices are connected in series or in parallel to obtain electric power for driving an electric vehicle and a necessary control circuit is further added will be described.

(Power supply device for hybrid vehicle)

Fig. 13 shows an example of a hybrid vehicle-mounted power supply device that travels using both an engine and a motor. The vehicle HV having the power supply device mounted thereon shown in the figure includes a vehicle main body 91, an engine 96 and a traveling motor 93 for causing the vehicle main body 91 to travel, wheels 97 driven by the engine 96 and the traveling motor 93, a power supply device 100 for supplying electric power to the motor 93, and a generator 94 for charging a battery of the power supply device 100. The power supply device 100 is connected to the motor 93 and the generator 94 via a DC/AC inverter 95. In the vehicle HV, the battery of the power supply device 100 is charged and discharged and travels by both the motor 93 and the engine 96. The motor 93 is driven to run the vehicle in a region where the engine efficiency is low, for example, at the time of acceleration or at the time of low-speed running. Electric power is supplied from the power supply device 100 to the motor 93 to drive the motor 93. The generator 94 is driven by the engine 96 or by regenerative braking when braking is applied to the vehicle, thereby charging the battery of the power supply device 100. As shown in fig. 13, the vehicle HV may also have a charging plug 98 for charging the power supply device 100. The power supply device 100 can be charged by connecting the charging plug 98 to an external power supply.

(Power supply device for electric vehicle)

Fig. 14 shows an example of a power supply device mounted on an electric vehicle that travels only by a motor. The vehicle EV shown in the figure, which is equipped with a power supply device, includes a vehicle main body 91, a traveling motor 93 for traveling the vehicle main body 91, wheels 97 driven by the motor 93, a power supply device 100 for supplying electric power to the motor 93, and a generator 94 for charging a battery of the power supply device 100. The power supply device 100 is connected to the motor 93 and the generator 94 via a DC/AC inverter 95. Electric power is supplied from the power supply device 100 to the motor 93 to drive the motor 93. The generator 94 is driven by energy generated when the vehicle EV is regeneratively braked, and charges the battery of the power supply device 100. Vehicle EV has a charging plug 98, and power supply device 100 can be charged by connecting charging plug 98 to an external power supply.

(Power supply device for electric storage device)

The present invention does not limit the use of the power supply device to the power supply of the motor for running the vehicle. The power supply device according to the embodiment can also be used as a power supply for a power storage device that charges and stores a battery with electric power generated by solar power generation, wind power generation, or the like. Fig. 15 shows an electricity storage device in which a battery of the power supply device 100 is charged by a solar battery 82 and stored.

The power storage device shown in fig. 15 charges the battery of the power supply device 100 with electric power generated by the solar battery 82 disposed on the roof, the roof platform, or the like of a building 81 such as a house or a factory. In this power storage device, after the battery of the power supply device 100 is charged by the charging circuit 83 using the solar battery 82 as a charging power supply, electric power is supplied to the load 86 through the DC/AC inverter 85. Therefore, the electrical storage device has a charge mode and a discharge mode. In the power storage device shown in the figure, a DC/AC inverter 85 and a charging circuit 83 are connected to a power supply device 100 via a discharging switch 87 and a charging switch 84, respectively. The on/off of the discharge switch 87 and the charge switch 84 is switched by a power supply controller 88 of the electrical storage device. In the charging mode, the power controller 88 switches the charging switch 84 on and the discharging switch 87 off, and allows the power supply device 100 to be charged from the charging circuit 83. When the charging is completed and the battery is in a full-charge state, or when the capacity is charged to a predetermined value or more, the power controller 88 turns off the charging switch 84 and turns on the discharging switch 87 to switch to the discharging mode, thereby allowing the discharging from the power supply device 100 to the load 86. Further, if necessary, the power supply to the load 86 and the charging to the power supply device 100 may be performed simultaneously with the charging switch 84 being turned on and the discharging switch 87 being turned on.

Further, although not shown, the power supply device may be used as a power supply for an electric storage device that charges and stores a battery with midnight electric power at night. The power supply device charged by the midnight power can be charged by the midnight power which is the surplus power of the power station, and output power during daytime when the power load is large, and limit peak power during daytime to be small. Further, the power supply device can also be used as a power supply for charging using both the output of the solar battery and the midnight power. The power supply device can effectively utilize both the electric power generated by the solar cell and the midnight electric power, and can efficiently store electricity while taking weather and power consumption into consideration.

The power storage device as described above can be suitably used for applications such as a backup power supply device that can be mounted on a rack of a computer server, a backup power supply device for a wireless base station such as a mobile phone, a power supply for power storage for home use or factory use, a power supply for street lamps, and the like, a power storage device combined with a solar cell, a signal device, a backup power supply for a traffic display for a road, and the like.

Industrial applicability

The power supply device of the present invention, and an electrically powered vehicle and an electric storage device using the power supply device, a fastening member for a power supply device, a method for manufacturing a power supply device, and a method for manufacturing a fastening member for a power supply device can be suitably used as a power supply for large current used for a power supply of a motor or the like for driving an electrically powered vehicle such as a hybrid vehicle, a fuel cell vehicle, an electric vehicle, and an electric motorcycle. Examples of the power supply device include a plug-in hybrid electric vehicle, a hybrid electric vehicle, and an electric vehicle that can switch between an EV running mode and an HEV running mode. Further, the present invention can be suitably used for applications such as a backup power supply device that can be mounted on a rack of a computer server, a backup power supply device for a wireless base station such as a mobile phone, a power supply for power storage for home use and factory use, a power supply for street lamps, a power storage device combined with a solar cell, a backup power supply for signal equipment, and the like.

Description of the reference numerals

100. A power supply device; 1. a secondary battery cell; 1X, terminal surface; 1a, an outer can; 1b, a sealing plate; 2. an electrode terminal; 10. a battery laminate; 15. 15', a fastening member; 15a, a middle portion; 15b, 15 b', a locking block; 15c, 15 c', a fastening portion; 15ac, fastening main surface side through hole; 15bc, a fastening-side through hole; 15d, bending sheets; 15f, bolts; 15g, welding seams; 15h, fixing the area; 16. an insulating spacer; 17. an end face spacer; 20. an end plate; 20b, a step portion; 20c, end plate threaded holes; 81. a building; 82. a solar cell; 83. a charging circuit; 84. a charging switch; 85. a DC/AC inverter; 86. a load; 87. a discharge switch; 88. a power supply controller; 91. a vehicle main body; 93. an electric motor; 94. a generator; 95. a DC/AC inverter; 96. an engine; 97. a wheel; 98. a charging plug; 800. a power supply device; 801. a secondary battery cell; 810. a battery laminate; 815. a fastening member; 815a, a fastening main surface; 815b, a locking block; 815g, fixing holes; 820. an end plate; 820b, a stopper; 820c, a fitting portion; 900. a power supply device; 901. a secondary battery cell; 902. a partition plate; 903. an end plate; 903a, a corner; 904. tightening the strip; 904b, letter L-shaped portion; 906. a bolt; l1, first straight line; l2, second straight line; HV, EV, vehicle.