WO2014068740A1

WO2014068740A1 - Cell unit

Info

Publication number: WO2014068740A1
Application number: PCT/JP2012/078277
Authority: WO
Inventors: 尚貴木村; 心 ▲高▼橋; 玲緒小林; 栄二關
Original assignee: 株式会社日立製作所
Priority date: 2012-11-01
Filing date: 2012-11-01
Publication date: 2014-05-08

Abstract

The present invention provides a cell unit that can be connected in series or parallel without using a bus bar and without welding or bonding using a fixing tool such as a bolt. The characteristic of the present invention is, e.g., as follows. A cell unit in which a plurality of single cells provided with a cell can housing a positive electrode, a negative electrode, and a separator, and a positive electrode terminal and a negative electrode terminal protruding from the cell can, are stacked and electrically connected to each other; the positive electrode terminal and the negative electrode terminal of single cells that are arranged adjacent to each other being in contact with each other at a surface perpendicular to the direction in which the single cells are stacked, forming a terminal contact part; an insulation block being provided between a plurality of terminal connection parts formed by stacking a plurality of the single cells; and the insulation block being in contact with the terminal connection parts. The present invention can thereby provide an inexpensive and lightweight cell unit.

Description

Battery unit

In recent years, each automobile manufacturer has developed an electric vehicle (EV) and a hybrid electric vehicle (HEV) in which a part of the drive is assisted by an electric motor due to the problem of global warming and depleted fuel. High performance secondary batteries are required as their power source, but high safety is essential for their widespread use in the market. In addition, large-sized secondary batteries are also attracting attention as household storage batteries, and development of a battery unit in which a large number of batteries (unit cells) are combined is also being pursued in line with the increase in voltage.

In general, battery units are connected in series to achieve high voltage. At that time, the positive electrode terminal (or negative electrode terminal) of the unit cell and the negative electrode terminal (or positive electrode terminal) of another unit cell are connected by a metal (aluminium, copper, nickel, alloy system, etc.) Is common (Patent Document 1).

JP, 2009-87720, Patent Document 1: Japanese Patent Application Publication No. 2008-186725

In Patent Document 1, the bus bar is a metal, which causes an increase in weight and cost.

Then, in patent document 2, the invention which bonds single cells together by bolting without using a bus bar is reported by changing the shape of a terminal itself. However, with the increase in size of HEVs and EVs, the number of single cells is large, and the time and labor for bolting single cells to each other is large.

The present invention provides battery units that can be connected in series or in parallel without using a bus bar and without using joining or welding with fasteners such as bolts.

The features of the present invention are, for example, as follows.

A battery unit in which a plurality of unit cells including a battery can accommodating a positive electrode, a negative electrode, and a separator, and a positive electrode terminal and a negative electrode terminal protruding from the battery case are stacked and electrically connected to each other The positive electrode terminal and the negative electrode terminal of the unit cells arranged are in contact with each other by a plane perpendicular to the stacking direction of the unit cells, forming a terminal contact portion, and the plurality of unit cells A battery unit in which an insulating block is provided between the plurality of terminal connection portions formed by stacking, and the insulating block is in contact with the terminal connection portion.

The present invention can provide a low cost and lightweight battery unit. Problems, configurations, and effects other than those described above will be apparent from the description of the embodiments below.

External perspective view of single cell Battery disassembled perspective view Perspective view of winding group Battery unit connected in series Array appearance perspective view of a battery unit having an insulating block Battery unit example using rows of insulating blocks on both sides Example of parallel connection of battery units connected in series

Hereinafter, embodiments of the present invention will be described using the drawings and the like. The following description shows specific examples of the content of the present invention, and the present invention is not limited to these descriptions, and various modifications by those skilled in the art can be made within the scope of the technical idea disclosed herein. Changes and modifications are possible. For example, although a prismatic lithium ion secondary battery is described as an example of a battery, other shapes such as a capacitor and a nickel hydrogen secondary battery, and other shapes such as a laminate cell can be applied, and the present invention is not limited thereto. Further, although the battery units are mainly described by taking serial connection as an example, they may be parallel.

FIG. 1 shows a perspective view of the appearance of the unit cell 25. As shown in FIG.

The unit cell 25 includes a battery can 6 and a battery lid 12. The winding group 3 is housed in the battery can 6, and the upper opening of the battery can is sealed by the battery lid 12. The battery lid 12 is welded to the battery can 6 by laser welding, and the battery can 6 and the battery lid 12 constitute a battery case. The battery cover 6 is provided with a positive electrode terminal 19 and a negative electrode terminal 20. The winding group 3 is charged via the positive electrode terminal 19 and the negative electrode terminal 20, and power is supplied to the external load.

A pressure release valve 17 is integrally provided on the battery lid 12, and when the pressure in the battery container rises, the pressure release valve 17 is opened to discharge gas from the inside, and the pressure in the battery container is reduced. Thereby, the safety of the unit cell 25 is secured.

From the appearance of the unit cell 25, the positive electrode terminal 19 and the negative electrode terminal 20 can be seen.

The positive electrode terminal 19 and the negative electrode terminal 20 have terminal structures directed in different directions in the thickness direction of the battery. In the case of connecting in series in the present invention, it is possible to configure a battery unit by alternately arranging two types of single cells using another single cell whose terminal direction is reversed in positive and negative directions.

The internal configuration of the battery will be described in more detail. FIG. 2 is an exploded perspective view of a prismatic secondary battery according to the present embodiment.

The cells 25 are respectively connected to the positive and negative

electrode current collectors

9 and 10 connected to the winding group 8 and penetrate the battery cover 12 in a state of being electrically insulated by the gasket 11 and the insulating ring 13 The positive electrode terminal 14 and the negative electrode terminal 15, which are electrically connected, the insulating sheet 7 and the battery can 6, which electrically insulate the inside of the battery can 6, and the injection port sealed after the electrolyte is injected into the battery It can be configured by the liquid stopper 16. After the electrolytic solution is injected into the battery container 25 from the liquid injection port 18 into the unit cell 25, the liquid injection port is sealed by the liquid injection valve.

The electrolyte used was an electrolyte of 1 M LiPF ₆ dissolved in a solvent of EC: EMC = 1: 3 vol%. Other electrolytes include, for example, ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, γ-butyrolactone, γ-valerolactone, methyl acetate, ethyl acetate, methyl propionate, tetrahydrofuran, 2 -Methyltetrahydrofuran, 1,2-dimethoxyethane, 1-ethoxy-2-methoxyethane, 3-methyltetrahydrofuran, 1,2-dioxane, 1,3-dioxane, 1,4-dioxane, 1,3-dioxolane, 2 Non-aqueous solvents selected from at least one or more selected from, for example, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiN (C ₂ F ₅ SO ₂₎ ₂₎ than ₂ or the like Without even it may be a known electrolyte used in the battery, such as one or more selected solid electrolyte or gel electrolyte or a molten salt having a conductivity of the lithium salt and the organic electrolyte or a lithium ion dissolved. The pressure release valve 17 is formed integrally with or separately from the battery can 6 or the battery lid 12 which forms the outer shell of the battery.

FIG. 3 is an exploded perspective view of the winding group 8. In the winding group 8, the strip-shaped positive electrode 3 and the strip-shaped negative electrode 5 are wound via the strip-shaped two separators 4. The positive electrode uncoated portion 2 and the negative electrode uncoated portion 1 are wound in an oval shape in cross section so as to be positioned on both end surfaces of the wound group.

In the wound group 8 obtained, the uncoated parts 1 and 2 are arranged on the opposite side to each other.

The positive electrode 3 constituting the winding group 8 has an aluminum foil as a positive electrode current collector foil. On both sides of the aluminum foil, Li Ni _1/3 Co _1/3 Mn _1/3 O ₂ of lithium-containing transition metal double oxide was used as a positive electrode active material. Besides, various lithium transition metal complex oxides can be used for the positive electrode active material of the lithium ion secondary battery. For example, it is possible to replace part of Ni, Co, Mn, and the like of the positive electrode active material such as lithium nickelate, lithium cobaltate, and lithium manganate with one or more transition metals.

As the positive electrode active material mixture, in addition to the positive electrode active material, a conductive material of a carbon material and a binder (binder) of polyvinylidene fluoride (hereinafter abbreviated as PVDF) were used.

At the time of coating of the positive electrode active material mixture on an aluminum foil, the viscosity is adjusted with a dispersion solvent such as N-methylpyrrolidone (hereinafter abbreviated as NMP).

At this time, the uncoated part 2 to which the positive electrode active material mixture is not applied is formed on the side edge on one side in the long side of the aluminum foil. That is, the aluminum foil is exposed in the positive electrode uncoated portion 2. The density of the positive electrode 3 is adjusted by a roll press after drying. On the other hand, the negative electrode 5 has copper foil as a negative electrode current collector foil. Amorphous carbon was used as the negative electrode active material on both sides of the copper foil. In addition, as the negative electrode active material, materials capable of reversibly absorbing and releasing lithium ions, such as carbon materials such as natural graphite and artificial graphite, can be used.

As the negative electrode active material mixture, other than the negative electrode active material, acetylene black or graphite was used as a conductive material, and a PVDF binder was further used. At the time of coating of the negative electrode active material mixture on copper foil, the viscosity is adjusted with a dispersion solvent such as NMP.

At this time, the uncoated part 1 to which the negative electrode active material mixture is not applied is formed on the side edge on one side in the length direction of the copper foil. That is, in the negative electrode uncoated portion 1, the copper foil is exposed. The density of the negative electrode 5 is adjusted by a roll press after drying. The length of the negative electrode 5 is set so that the positive electrode 3 does not protrude from the negative electrode 5 in the winding innermost and outermost peripheries when the positive electrode 3 and the negative electrode 5 are wound. Is set to be longer than

Further, the width (length in the direction of WH) of the coated portion of the negative electrode active material mixture is such that the coated portion of the positive electrode active material mixture protrudes from the coated portion of the negative electrode active material mixture in the longitudinal direction of the wound group In order to prevent this, the width is set to be longer than the width of the coated portion of the positive electrode active material mixture.

FIG. 4 is an external appearance perspective view of the battery unit. A battery unit can be configured by stacking a plurality of unit cells 25 each having a rectangular case.

The shape of the terminal for stacking the unit cells 25 is not particularly limited, but a shape such as a crank type (chair type) or an L shape can be used. By using a crank-type terminal having a larger number of bends as shown in FIGS. 1 and 4 rather than simply making it L-shaped, it is possible to withstand a change in size or a positional deviation due to a stress in the stacking direction. In particular, when the insulating block 21 described later is provided between the terminal connection portions 28, the position of the terminal connection portion 28 is forcibly fixed by the insulating block 21. Preferably, the shape of the terminal is a crank type. On the other hand, the L-shaped shape has the advantage of being easy to manufacture.

In the single cell 25, the contact surfaces of the positive electrode terminal 19 and the negative electrode terminal 20 are directed in the opposite direction to the stacking direction of the single cell 25. Furthermore, in order to connect a plurality of unit cells 25 in series, it is preferable to prepare and stack two types of unit cells 25 whose terminal directions are reversed as shown in FIG. 4. Two types of single cells 25 whose terminal directions are reversed are alternately arranged, and the positive electrode terminal 19 and the negative electrode terminal 20 of the single cells 25 facing each other are combined to constitute a battery unit.

Further, the terminals connected in series are in contact with each other perpendicularly to the stacking direction of the unit cells 25 and in parallel to the stacking surface. The contact surface of the terminal contact portion 28 formed by the contact between the positive electrode terminal 19 and the negative electrode terminal 20 is preferably a surface parallel to the lamination surface of the unit cell. This is because when the terminals connected in series have a plane perpendicular to the stacking direction of the unit cells and parallel to the stacking surface of the unit cells, the stress in the stacking direction caused by the stacking of the unit cells 25 This is because the terminal 19 and the negative electrode terminal 20 can be crimped together, which is structurally efficient in manufacturing. Moreover, it is because fixation of the insulating block 21 mentioned later becomes easy, and productivity improves.

FIG. 5 is an external appearance perspective view of the battery unit having the insulating block 21. FIG.

By arranging the cells 25 as shown in FIG. 4, a terminal contact portion 28 in which the positive electrode terminal 19 and the negative electrode terminal 20 are combined is formed between the cells 25. By providing the insulating block 21 between the terminal contact portions 28, the contact between the positive electrode terminal 19 and the negative electrode terminal 20 is assisted. Furthermore, the positive electrode terminal 19 and the negative electrode terminal 20 can be pressure-bonded by the external stress 24 in the thickness direction of the unit cell 25, and the contact between the positive electrode terminal 19 and the negative electrode terminal 20 can be made reliable. The external stress 24 can be generated, for example, by putting the battery unit of FIG. 5 in a case and tightening it from the outside, or by providing a fastener and tightening. The external stress 24 is preferably within a range that can be handled by securing the battery unit, and is preferably 1 kPa or more and 10 MPa or less. In particular, 0.1 MPa or more and 2 MPa or less is the most preferable. Moreover, although the site | part to be crimped | bonded is the terminals mutually connected at least in series or parallelly, single cells may also be crimped | bonded.

With this structure, it is possible to easily connect in series without fasteners such as bus bars and bolts, so a low-cost and lightweight battery unit can be realized.

Furthermore, in order to take out the electricity of the series battery unit, metal blocks 22 and 23 can be provided on the positive electrode terminal 19 and the negative electrode terminal 20 of the outermost cell 25 respectively. The insulating block 21, the metal blocks 22 and 23, and the positive and

negative electrode terminals

19 and 20 can be integrated and connected in series by the external stress 24.

The insulating block 21 is not particularly limited as long as it is an insulator, but a material excellent in heat dissipation, for example, a resin such as insulating epoxy or silicone, a metal oxide such as alumina or magnesium oxide, or these oxides or insulators It is preferable to use an insulating metal such as a metal coated with a conductive resin or the like, a Peltier element, or the like. By using a material excellent in heat dissipation for the insulating block 21, the heat generated inside the unit cell 25 and transferred to the terminal portion can be efficiently dissipated from the insulating block 21. Furthermore, by making the insulating block 21 hollow, it is possible to make the structure more excellent in the heat dissipation effect. In addition, a refrigerant can be disposed to further circulate the refrigerant.

As shown in FIG. 5, a space is formed by the insulating block near the pressure release valve 17 of the battery unit. In this space, the insulating block can be used as a gas discharge path. Furthermore, a voltage detection mechanism may be provided in the insulating block, and a voltage monitor of single cells connected in series may be installed.

FIG. 6 is an external appearance perspective view of an array of battery units in which a row of single cells 25 is provided on both sides of the insulating block 21. FIG. 6 shows a battery unit in which the battery unit of FIG. 5 is 90 degrees horizontal and the row of insulating blocks is used on both sides. By providing the row of single cells 25 on both sides of the insulating block 21, the structure is excellent in volumetric efficiency and is more efficient as a gas discharge path.

FIG. 7 shows an example in which series-connected battery units are connected in parallel by using a row of insulating blocks 21 on both sides. Similar to FIG. 6, the battery unit is excellent in volumetric efficiency and more effective as a gas discharge path.

As described above, according to the present invention, it is possible to connect in series or in parallel without using a bus bar between terminals and without using bonding or welding with a fixing tool, and a low cost and lightweight battery unit can be provided.

1: Negative electrode uncoated portion 2: Positive electrode uncoated portion 3: Positive electrode 4: Separator 5: Negative electrode 6: Battery can 7: Insulating sheet 8: Winding group 9: Positive electrode current collector plate 10: Negative electrode current collector plate 11: Gasket 12: Battery cover 13: Insulating ring 14: Positive electrode rivet 15: Negative electrode rivet 16: Liquid injection plug 17: Pressure release valve 18: Liquid injection port 19: Positive electrode terminal 20: Negative electrode terminal 21: Insulating block 22: Outermost single cell Positive electrode side metal block 23: outermost single cell negative electrode side metal block 24: external stress 25: single cell 26: battery unit A in which four single cells are connected in series
27: Battery unit B in which four single cells are connected in series
28: Terminal contact portion

Claims

A battery can containing the positive electrode, the negative electrode, and the separator;
A battery unit in which a plurality of unit cells including a positive electrode terminal and a negative electrode terminal protruding from the battery can are stacked and electrically connected to each other,
The positive electrode terminal and the negative electrode terminal of the unit cells arranged adjacent to each other are in contact by a plane perpendicular to the stacking direction of the unit cells, forming a terminal contact portion,
An insulating block is provided between the plurality of terminal connection portions formed by stacking the plurality of unit cells,
The battery unit in which the insulating block is in contact with the terminal connection portion.
In claim 1,
The positive electrode terminal and the negative electrode terminal of the unit cell face in different directions with respect to the stacking direction of the unit cell,
A battery unit in which the positive electrode terminal and the negative electrode terminal are bent in a crank shape or an L shape.
In claim 1 or claim 2,
A battery unit in which the positive electrode terminal and the negative electrode terminal of the unit cells disposed adjacent to each other are crimped by an external stress via the insulating block.
In any one of claims 1 to 3,
A battery unit in which a plurality of the unit cells are connected in series or in parallel.
In any one of claims 1 to 4,
The insulating block is a battery unit including one or more of an insulating epoxy, a silicone resin, an insulating metal, and a Peltier element.
In claim 5,
The battery unit, wherein the insulating metal is any one or more of alumina, magnesium oxide, and a metal coated with an insulating resin.
In any one of claims 1 to 6,
A battery unit in which the positive electrode terminal or the negative electrode terminal of the unit cell positioned at the outermost side of the stacked unit cells has a metal block.
In any one of claims 1 to 7,
The insulating block is a battery unit that is hollow.