JP2001256941A - Battery module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a superior flat-type battery module using nonaqueous secondary battery that is prevented from lowering energy density and has a high security possible to obviate such accident as ignition or explosion in emergency. SOLUTION: The battery module loads a plurality of unit cell sheets 10 by disposing the parallel inside an armored container 11 and the these plural unit cells 10 are electrically connected. The armored container 11 has a plurality of striated guides 12 that can guide at least a peripheral part of the said unit cell on facing walls inside of the said armored container 11 so that the plural unit cells 10 can be disposed in parallel at a necessary interval. The striated guides 12 are constituted so that the unit cells 10 can break away from the guides 12 when the unit cells 10 swell to mutually push themselves in their thickness direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a high-capacity battery module in which a plurality of 30 Wh-class lithium ion secondary batteries are connected.

[0002]

2. Description of the Related Art In recent years, from the viewpoint of global environmental problems and effective use of energy for resource saving, a home-use decentralized power storage system for late-night power storage and solar power generation, or a power storage system for electric vehicles, etc. Is attracting attention.
Further, JP-A-6-86463 proposes a total system combining electricity supplied from a power plant, gas cogeneration, a fuel cell, a storage battery, and the like, as a system capable of supplying energy to energy consumers under optimal conditions. I have. Unlike secondary batteries for portable devices having an energy capacity of 10 Wh or less, large secondary batteries with large capacities are required for these storage batteries. Also, in these systems, a plurality of secondary batteries are stacked in series and used as an assembled battery having a voltage of, for example, 50 to 400 V. In most cases, a lead battery is used.

On the other hand, in the field of small rechargeable batteries for portable equipment, nickel-metal hydride batteries and lithium rechargeable batteries have been developed as new types of batteries in order to meet the needs of small size and high capacity.
Batteries having a volume energy density of 0 Wh / l or more are commercially available. Lithium-ion batteries in particular have the potential for a volume energy density exceeding 350 Wh / l, and their reliability, such as safety and cycle characteristics, is superior to lithium secondary batteries using lithium metal as the negative electrode. It is dramatically extending.

[0004] In response to this, in the field of large batteries for power storage systems, lithium ion batteries are targeted as candidates for high energy density batteries, and development is being actively promoted by the Lithium Battery Power Storage Technology Research Association (LIBES) and others. Have been.

[0005] These large lithium ion batteries have an energy capacity of about 100 Wh to 400 Wh. In addition, the volume energy density is 200 to 300 Wh / l, which is at the level of small rechargeable batteries for portable devices. Its shape is 50-70mm in diameter, length 25
A typical example is a flat prism having a cylindrical shape of 0 mm to 450 mm, a square shape having a thickness of 35 mm to 50 mm, or an oblong shape.

When the above-described large batteries are used in a power storage system, generally, 4 to 10 large batteries (unit cells) are connected in series to form a 15 V to 50 V battery module, and these battery modules are connected in series and in parallel. It is often used as a power storage system that is connected and has a predetermined voltage and capacity.

On the other hand, as for a thin lithium secondary battery, for example, a film battery in which a thin film having a thickness of 1 mm or less in which metal and plastic are laminated is accommodated in a thin outer package (Japanese Patent Application Laid-Open Nos. Japanese Patent Application Laid-Open No. 8-19588), a small rectangular battery having a thickness of about 2 mm to 15 mm
No. 204, JP-A-8-138727, JP-A-9-213286, etc.) are known. In any case, the purpose is to reduce the size and thickness of portable devices. For example, a thin battery having a thickness of several mm and an area of about JIS A4 size that can be stored in the bottom surface of a portable personal computer has been disclosed. JP 5-
283105), the energy capacity is 10 Wh or less, which is too small for a secondary battery for a power storage system. Furthermore, when these thin batteries are connected in series or in parallel to form a battery module, the capacity is small, and no special measures are taken, such as simply stacking them without considering heat dissipation.

[0008]

In general, in a lithium ion battery, if the battery is malfunctioned due to a malfunction of the device or is overused or short-circuited externally due to misuse by a user, the inside of the battery is heated and the electrolyte is decomposed. For example, gas is generated inside. A safety valve is provided to prevent an accident caused by an increase in the internal pressure. This kind of safety valve is
The battery container opens due to the deformation of the battery container due to the expansion of the battery container due to the increase of the internal pressure. The unit cell having such a safety valve operates normally even in the module unless there is an obstacle in the opening direction of the safety valve.

However, in some flat type batteries, the safety valve is provided on a wide plane in the thickness direction due to its thin structure. In this case, the above-mentioned battery is liable to expand, and the degree of expansion is hindered. There is a problem that the operation of the safety valve is delayed.

On the other hand, when the above-mentioned battery is used in a power storage system, generally, 4 to 10 large batteries (unit cells) are connected in series to form a 15 V to 50 V battery module, and these battery modules are connected in series. However, it is often used as a power storage system having a predetermined voltage and capacity. or,
In general, in order to improve the volume energy density in the module, the cells are arranged with the interval between the cells as narrow as possible.

Therefore, each of the cells arranged in parallel in the thickness direction in the module is in an environment where expansion is easily hindered. This can be avoided if the battery module is provided with a sufficient space between the cells, but the volume energy density is reduced.

[0012] An object of the present invention is to solve the above problems by suppressing a decrease in energy density in a module.
A battery module using a flat non-aqueous secondary battery with excellent safety that can prevent accidents such as ignition or explosion in the event of an abnormality by operating a safety valve under the same conditions as a single cell. It is in.

[0013]

SUMMARY OF THE INVENTION The object of the present invention is to provide a flat battery container having a non-aqueous electrolyte containing a positive electrode, a negative electrode and a lithium salt, having a thickness of less than 12 mm, and having an energy capacity of at least 30 Wh and a volume of at least 30 Wh. Energy density is 18
A battery module for mounting a plurality of cells having a capacity of 0 Wh / l or more in parallel in an outer container and electrically connecting the plurality of cells, wherein the outer container includes the plurality of cells. A plurality of rows of groove-shaped guide portions that can guide at least a part of a peripheral portion of the unit cell on the inner wall surface of the outer container so that the plurality of unit cells can be arranged in parallel at required intervals; The guide portion is characterized in that when the cells are expanded and the cells are pressed against each other in the thickness direction, the cells can be detached from the channel-shaped guide portion. Achieved by battery module.

It is preferable that the groove-shaped guide portion is formed on a bottom wall surface of the outer container.

It is preferable that the groove-shaped guide portion is formed on a side wall surface of the outer container.

The groove-shaped guide portion is formed by a concave groove;
It is preferable that the groove width is formed so that the groove width gradually decreases toward the bottom of the groove.

[0017] The groove-shaped guide may be formed by convex walls arranged opposite to each other, and may have a weak point which can be easily bent at a base end of the convex wall.

It is preferable that the battery container has a flange on a peripheral portion, and the flange is fitted in the groove-shaped guide portion.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described.
This will be described with reference to the accompanying drawings. FIG. 1 shows an outer structure of a battery module as an example of an embodiment of the present invention, FIG. 2 shows how to arrange cells arranged in an assembled battery, and FIG. 3 shows a flat battery having a thickness of less than 12 mm, which is a cell. Are respectively shown.

More specifically, as shown in FIG.
The battery cell 10 with the battery is inserted from above into a groove-shaped guide portion 12 provided in an outer container 11 of the battery, arranged in parallel as shown in FIG. 2, and then another connection plate B for connecting the connection plates A to each other. Use screws to connect them in series.

The single cell is provided with a battery case C comprising an upper lid 1 and a bottom container 2 in FIG. 3, and the battery case 3 contains an electrode laminate in which a positive electrode and a negative electrode face each other with a separator interposed therebetween. . The positive electrode current collector and the negative electrode current collector are electrically connected to the positive terminal 3 and the negative terminal 4, respectively.
The positive terminal 3 and the negative terminal 4 are mounted in a state insulated from the battery case. A connection plate A is attached to the positive electrode terminal 3 and the negative electrode terminal 4, and the connection plate A can be connected in series with another unit cell by using another connection plate B.

The top lid 1 and the bottom container 2 are welded all around at the location of the flange 13. Top lid 1 or bottom container 2
Has a safety valve 5 that is released when the internal pressure inside the battery rises.
Is provided. In the illustrated example, the safety valve 5 is formed by four linear thin portions on one wide plane of the flat cell 10 so as to cross a diagonal line.
Although not shown, the safety valve may be formed on the upper surface of the flat battery container.

The dimensions of the unit cell are, for example, 300 mm long × 210 mm wide × 6 mm thick, and LiMn ₂ O ₄ ,
In the case of a lithium secondary battery using a carbon material for the negative electrode, home energy storage systems (nighttime power storage, cogeneration,
It can be used for a power storage system of an electric vehicle or the like, and can have a large capacity and a high energy density. In this case, the energy capacity is preferably at least 30 Wh, more preferably at least 50 Wh, and the energy density is preferably at least 180 Wh / l.
More preferably, it is 200 Wh / l or more. When the energy capacity is less than 30 Wh or when the volume energy density is less than 180 Wh / l, the capacity is small for use in a power storage system, and it is necessary to increase the number of series-parallel batteries in order to obtain a sufficient system capacity. In addition, it is not preferable for a power storage system because a compact design is difficult. In such a secondary battery,
As the electrolyte, for example, a non-aqueous electrolyte containing a lithium salt can be used.

The thickness t of the unit cell of the present embodiment is preferably less than 12 mm, more preferably less than 10 mm, and even more preferably less than 8 mm. The lower limit of the thickness is practically 2 mm or more in consideration of the filling rate of the electrode and the battery size (the smaller the thickness, the larger the area for obtaining the same capacity). When the thickness of the battery is 12 mm or more, it becomes difficult to sufficiently dissipate the heat generated inside the battery to the outside, or the temperature difference between the inside of the battery and the vicinity of the battery surface increases, resulting in a difference in internal resistance. The amount of charge and the variation in the voltage at the time become large. Although the specific thickness is appropriately determined according to the battery capacity and the energy density, it is preferable to design the thickness so as to obtain the expected heat radiation characteristics. In FIG. 2, eight cells are arranged.
In the battery module of the present invention, two or more single cells can be used. The desired number of cells is determined by the voltage, capacity, size,
It is appropriately determined according to the shape, voltage, capacity, shape, weight, and the like of the unit cell.

The shape of the non-aqueous secondary battery of the present embodiment is, for example, that the flat front and back surfaces are square, circular,
Various shapes such as an oval shape can be used. In the case of a square shape, the shape is generally a rectangle, but it can also be a polygon such as a triangle or a hexagon. Further, it may be a cylindrical shape such as a thin-walled cylinder. In the case of a cylindrical shape, the thickness of the cylinder is the thickness referred to here. Further, from the viewpoint of ease of manufacture, the flat front and back surfaces of the battery are preferably rectangular, and a notebook-type shape as shown in FIG. 3 is preferable.

The material used for the top cover 1 and the bottom container 2 serving as a battery case is appropriately selected depending on the use and shape of the battery, and is not particularly limited.
Aluminum and the like are common and practical. Also,
The thickness of the battery case is also appropriately determined depending on the use and shape of the battery or the material of the battery case, and is not particularly limited. Preferably, the thickness of the portion of 80% or more of the battery surface area (the thickness of the portion having the largest area constituting the battery case) is 0.2 mm or more. When the thickness is less than 0.2 mm, the strength required for battery production cannot be obtained, which is not desirable.
m or more. Further, it is desirable that the thickness of the portion is 1 mm or less. When the thickness exceeds 1 mm, the force for pressing down the electrode surface increases, but it is not desirable because the internal volume of the battery is reduced and a sufficient capacity cannot be obtained, or the weight increases, which is not desirable. Preferably it is 0.7 mm or less.

As described above, the thickness of the secondary battery is 12 mm
By designing the battery to be less than, for example, 30 Wh
When the battery has the above-mentioned large capacity and a high energy density of 180 Wh / l, the battery temperature rise is small even at the time of high-rate charge and discharge, and excellent heat radiation characteristics can be obtained. Therefore, heat storage of the battery due to internal heat generation is reduced, and as a result, thermal runaway of the battery can be suppressed, and a unit cell excellent in reliability and safety can be provided.

The outer package of the module will be described.
The outer container 11 is desirably an outer container into which the cells 10 can be inserted from above at a predetermined interval from the upper portion. Therefore, a groove shape for guiding at least a part of the peripheral portion of the cells 10 to the inner surface of the side wall of the outer container 11 is preferable. The guide unit 12 has a plurality of rows.

In the case of the flat battery shown in the drawing, a flange 13 having a thickness of 1 mm is present on the entire peripheral portion with a width of several millimeters. it can. For example, in the case of a simple flat box-shaped unit cell without such a flange (not shown)
Is fitted around the groove-shaped guide portion 12.

The groove-shaped guide portion 12 formed at the upper portion (entrance) of the outer container 11 is connected to the unit cells 10 arranged in parallel by the connection plate B with screws or the like. It is preferable that the parallel spacing is accurate. Therefore, it is preferable that the flange 13 be shaped so that the flange 13 does not shake when the flange 13 is fitted in the groove-shaped guide portion 12. For this reason, it is preferable that the cross-sectional shape of the groove-shaped guide portion 12 is rectangular and has a shape that fits exactly to the flange 13.
When 0 expands, it may hinder the expansion of the cell 10 and cause undesired deformation of the cell 10 (which can lead to an explosion). Therefore, the groove-shaped guide portion 12 on the upper part of the outer container 11 illustrated in FIG. 1 is formed to have a short width (length) of 10 mm from the upper end of the outer container 11, and the groove depth is about 0.5 mm. Is set. Although these dimensions are not particularly limited, the groove length of the groove-shaped guide portion 12 on the upper part of the outer container 11 is 2 to 15 for the purpose described above.
mm and the groove depth are preferably 2 mm or less. By setting the dimensions of the groove-shaped guide portion 12 in this way, even if the unit cell 10 expands, it can follow the expansion with only a slight deformation of the flange 13.

If the upper portion of the unit cell 10 is connected to the unit cell 10 by a connecting plate B (FIG. 4) for modularization, even if the unit cell 10 expands, the upper part of the unit cell 10 (the outer container 11 The side-by-side spacing at the insertion port end) cannot change significantly. However, as shown in FIG. 5, when the cell 10 located at the end of the outer container 11 expands around the center thereof and the lower part of the expanded cell 10 moves greatly, the upper part of the cell 10 As shown in the figure, the inclination is slight, but the inclination of the upper flange 13 of the unit cell 10 is reduced while the inclination of the flange 13 is reduced.
It is desirable to be able to move inside the groove-shaped guide portion 12 according to the inclination of the cell 10. Therefore, when the cells are expanded and pressed against each other, as shown in FIG. 5, the groove-shaped guides 12 cause the upper part of the cells 10 to be inclined in the groove-shaped guides 12 by the action of the expansion force. For example, the cross-sectional shape of the groove-shaped guide portion 12 can be a semicircle, an ellipse, an inverted trapezoid, or the like. The spacing between the unit cells 10 arranged in parallel does not come into contact with the terminals 3 and 4 (FIG. 3) and the connection plate A (FIG. 3) provided in the battery container of the unit cell 10 and takes into consideration the heat radiation space of the unit cells 10. There is no particular limitation as long as the predetermined interval can be maintained.

As described above, the unit cells 10 arranged in parallel
Are connected by a connection plate B, the cell 1
Even when 0 expands, the parallel spacing at the top does not change significantly, but the parallel spacing at the bottom is not connected, so that the bottom (lower) of the cell can move freely within the outer container 11. Since it is unstable, the groove-shaped guide portion is also formed at the lower part of the outer container 11. Therefore, it is formed on the bottom wall surface and / or the side wall surface inside the outer container 11 and below the substantially intermediate height. The groove-shaped guide portions formed on the bottom wall surface and the side wall surface of the outer container 11 have higher mobility when the cells 10 are expanded than the upper portion (the upper portion is connected by the connection plate B). ), The structure is such that the cell 10 is easily detached from its groove-shaped guide portion when expanded.

The groove-shaped guide portion 12 formed on the bottom wall surface of the outer container 11 is illustrated in FIGS.

The groove-shaped guide portion 12 on the bottom wall surface of the outer container 11 shown in FIG. 5 moves and separates from the groove-shaped guide portion 12 when a force is applied in the thickness direction of the cell 10. In order to make it possible, the groove is formed as a concave groove having a circular cross section so that the groove width becomes gradually narrower toward the groove bottom. This groove-shaped guide portion 12 has a maximum depth of 0.5 m in the illustrated example.
m, and the radius of curvature is 0.5 mm. Channel guide 12
The maximum depth is preferably 2 mm or less, and the radius of curvature in the case of an arc-shaped cross section is preferably 1.0 Xmm or more when the maximum depth is X mm. The reason is that if the maximum depth is larger than 2 mm, the cell 10 is hardly caught and it is difficult for the cell 10 to come off from the groove-shaped guide portion. This is because sliding in the groove-shaped guide portion 12 becomes worse.

The groove-shaped guide portion 12 on the bottom wall surface of the outer container 11 shown in FIG. 7 is formed in a groove shape by arranging a rail-shaped convex wall 20 opposite thereto, and a weak point portion 21 which is easily bent at the base end of the convex wall 20.
Are formed. In the illustrated example, the weak point portion 21 is formed by a thin portion. However, the weak point portion 21 may be formed by a perforated one in which pores are continuously arranged linearly. Such a convex wall 20 is used for the cell 10
However, as shown in FIG. 5 and FIG. 6, when the force is applied to the lower part of the unit cell 10 and the weak point part 21 is bent, the unit 21 is allowed to expand and the safety valve operates properly.

The groove-shaped guide portion 12 on the bottom wall surface of the outer container 11 shown in FIG. 8 is formed as a concave groove having a substantially inverted trapezoidal cross section, and the width of the groove is gradually narrowed toward the groove bottom. ing. Also in this case, it is preferable that the groove depth of the groove-shaped guide portion 12 be 2 mm or less as in the case of the above-described circular arc shape. And the width of the groove bottom is the width of the cell 10,
That is, in the illustrated example, it is preferable that the width is substantially equal to the width of the flange 13 in order to accurately guide the cell 10. Also,
The maximum width of the groove opening corresponding to the long side of the inverted trapezoidal shape is
From the viewpoint of improving the slippage of the flange 13 at 0, it is preferable that the width is about 1.5 to 3 times the groove bottom width.

According to the battery module having the above configuration, even if the unit cell expands as shown in FIGS. 5 and 6 due to the above-described factors, the unit cell 10 expands due to the expansion.
Are separated from the groove-shaped guide portion 12 by pressing each other, and the safety valve can be reliably operated.

[0038]

As is apparent from the above description, according to the battery module of the present invention, the outer container is formed so that the plurality of unit cells can be arranged in parallel at required intervals. The wall has a plurality of rows of groove-shaped guides capable of guiding at least a part of the peripheral portion of the cell, and the groove-shaped guide is such that the cells expand and the cells in the thickness direction. Since the cells are configured to be detachable from the groove-shaped guide portion when pressed together, the cells can be easily arranged in parallel at required intervals, and the safety valve has a flat shape. It can be operated properly when it is located on a wide flat surface of the vehicle.

Further, if the groove-shaped guide portion is formed on the bottom wall surface of the outer container, guiding of the cells at the bottom of the outer container is ensured, and the unit cells arranged in parallel are connected at the upper portion. Even in such a case, it is possible to secure appropriate expansion of the unit cell, which allows the unit cell to be detached from the groove-shaped guide portion without hindering movement of the unit cell larger than the upper part when the unit cell expands.

Further, if the groove-shaped guide portion is formed on the side wall surface of the outer container, the work of inserting the unit cell into the outer container becomes easy, and the groove-shaped guide portion is formed on the side wall surface of the outer container. In this case, it is easy to electrically connect the unit cells at the upper portion while keeping the interval between the unit cells arranged in parallel constant.

If the groove-shaped guide portion on the bottom wall surface of the outer container is formed by a groove, and the width of the groove is gradually reduced toward the bottom of the groove, the unit cell is manufactured. Since it can move along the gradually narrowing inclined surface when it expands, it can be easily separated.

Still further, if the battery container of the unit cell has a flange on a peripheral portion and the flange is fitted in the groove-shaped guide portion, the cell can be inserted into the groove-shaped guide portion. And the flange is deformed at the time of expansion to prevent deformation of the cell body.
Effects such as enabling appropriate expansion of the cell can be obtained.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an embodiment of a battery module according to the present invention.

FIG. 2 is a sectional view showing the internal structure of the battery module of FIG.

3 shows a unit cell of the battery module of FIG. 1, and (a)
Is a plan view, (b) is a front view, and (c) is a left side view.

FIG. 4 is a plan view showing a state in which the battery modules of FIG. 1 are electrically connected.

FIG. 5 is a cross-sectional view corresponding to FIG. 2 and showing a state where a unit cell is expanded.

FIG. 6 is a cross-sectional view corresponding to FIG. 2 and showing a state where a unit cell is expanded.

FIG. 7 is a partial cross-sectional view of a battery module showing another embodiment of the groove-shaped guide portion, which is a component of the present invention, in an enlarged manner.

FIG. 8 is a partial cross-sectional view of a battery module showing a further enlarged form of a groove-shaped guide portion as a component of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Top cover 2 Bottom container 3 Positive electrode terminal 4 Negative terminal 5 Safety valve 10 Single cell 11 Outer container 12 Groove-shaped guide part 13 Flange 20 Projecting wall 21 Weak point A Connection plate B Connection plate C Battery case

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shiro Kato 4-1-2 Hiranocho, Chuo-ku, Osaka-shi, Osaka Inside the Kansai New Technology Research Institute Co., Ltd. (72) Inventor Hajime Kinoshita 4 Hiranocho, Chuo-ku, Osaka-shi, Osaka 1-2, Kansai New Technology Research Institute Co., Ltd. (72) Shizukuni Yada 4-1-2, Hiranocho, Chuo-ku, Osaka-shi, Osaka F-term (reference) 5H011 AA01 AA06 AA13 BB03 BB05 CC06 5H029 AJ12 AK03 AL06 BJ02 BJ12 BJ27 DJ02 DJ12 EJ01 HJ04 HJ12 HJ19 5H040 AA07 AA12 AA37 AS01 AS07 AT02 AT06 AY05 AY10 AY12 CC13 CC33 CC35 CC38 NN01 NN03 NN05

Claims (6)

[Claims] 1. A unit cell comprising a positive electrode, a negative electrode and a non-aqueous electrolyte containing a lithium salt, sealed in a flat battery container having a thickness of less than 12 mm and having an energy capacity of 30 Wh or more and a volume energy density of 180 Wh / l or more. A plurality of the cells are arranged in parallel in the outer container and loaded, and a battery module for electrically connecting the plurality of unit cells, wherein the outer container includes the plurality of unit cells at required intervals. In order to be able to arrange in parallel, on the inner wall surface of the outer container, there are provided a plurality of rows of groove-shaped guide portions capable of guiding at least a part of the peripheral portion of the cell, and the groove-shaped guide portion includes A battery module, characterized in that the cells are detachable from the groove-shaped guide portion when the cells are expanded and pressed against each other in the thickness direction. 2. The battery module according to claim 1, wherein the groove-shaped guide portion is formed on a bottom wall surface of the outer container. 3. The battery module according to claim 1, wherein the groove-shaped guide portion is formed on a side wall surface of the outer container. 4. The groove-shaped guide portion is formed by a concave groove, and the groove width of the concave groove is formed so as to become gradually narrower toward the bottom of the concave groove. Item 4. The battery module according to any one of Items 1 to 3. 5. The groove-shaped guide section is formed by convex walls arranged to face each other, and has a weak point which is easily bent at a base end of the convex wall. The battery module according to any one of the above. 6. The battery module according to claim 1, wherein the battery container has a flange at a peripheral edge, and the flange is fitted to the groove-shaped guide portion.