JPH08321329A - Battery - Google Patents

Abstract

PURPOSE: To effectively prevent the drop of the battery performance of cells by bringing the cells and heat radiation plates into close adhesion to each other in a simple structure and in an ideal condition to produce heat radiation. CONSTITUTION: A battery is equipped with a plurality of cells 1 rectangular in external form, heat radiation plates 2 put between the single batteries 1, catching plates for catching the plural cells 1, and coupling parts for coupling the catching plates. The catching plates coupled with one another by the coupling parts catch the plural cells 1 stacked through the heat radiation plates 2 from both sides. The heat radiation plate 2 has an elastic transformed projection 2A projecting in the direction of stacking of the single batteries, and it forms a heat radiation path between the adjacent cells 1. The heat radiation plate 2 having the elastic transformed projection 2A is transformed, being caught between the cells 1 when the catching plates are fastened, and the heat radiation plate 2 is used also for the member to be pressed against the side face of the case 6 of the cell 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an assembled battery in which a plurality of rectangular cells are connected in a stacked state, and in particular,
The present invention relates to improvement of an assembled battery in which a heat dissipation plate is sandwiched between unit cells.

[0002]

2. Description of the Related Art An assembled battery in which a plurality of prismatic cells are stacked is
The internal cells cannot be dissipated effectively. The cells on both sides are
This is because the heat is dissipated from the side surface, but both side surfaces of the internal cell are in close contact with the adjacent cell. The temperature of a single battery that cannot effectively dissipate heat rises during charging and discharging, and the battery performance decreases. As shown in FIG. 2, FIG. 1 shows an increase in temperature of each battery when 10 prismatic nickel-hydrogen batteries are closely stacked and charged and discharged individually for each battery. 3 is a graph showing a decrease in battery capacity. In this figure, curve A shows the battery temperature at the end of charging, and curve B shows the ratio of the actually measured battery capacity to the nominal capacity of each cell. However, as for the battery capacity, the capacity of each unit cell is individually calculated after 100 charge / discharge cycles in which the unit cells 1 are connected in series, fully charged at 0.2C, and then discharged at 1 / 3C. It is the value measured in. As is clear from this figure, the unit cell 1 sandwiched in the middle has a high temperature and its capacity is significantly reduced. When multiple cells with different capacities are connected in series in this way, cells with smaller capacities are more susceptible to overcharge and over discharge than cells with large capacities, and cells with small capacities deteriorate faster. Will be invited. Even if a battery with a large capacity is normal, if a battery with a small capacity is deteriorated, there is a problem that the assembled battery connected in series cannot be used as a whole.

In order to prevent this adverse effect, an assembled battery in which prismatic unit cells are stacked and which effectively dissipates heat from the internal batteries is described in the following publication. Japanese Utility Model Publication No. 50-145427 (Fig. 3) Japanese Utility Model Publication No. 2-138858 (Fig. 4) Japanese Utility Model Publication No. 2-128368

The above publication describes an assembled battery in which a spacer is sandwiched between single cells to provide a heat radiation path. The publication describes an assembled battery in which a heat radiating plate having a heat radiating path is sandwiched between unit cells. The publication describes an assembled battery in which a high thermal conductive sheet is sandwiched between single cells.

[0005]

The battery pack described in the above publications can dissipate heat from the side surface of the case of the unit cell by means of a radiator plate sandwiched between the unit cells. Therefore, the heat generated inside the assembled battery can be radiated by the heat radiating plate, and the temperature rise of the internal cells can be reduced. However, in the battery packs described in these publications, it is extremely difficult to radiate heat from between the unit cells in an ideal state.

For example, the assembled battery described in FIG.
As shown in (1), since a gap is provided between the unit cells 1 to radiate heat, it is necessary to sufficiently ventilate the gap, and when the ventilation amount is small, the unit cells located in the middle cannot effectively dissipate heat. Furthermore, the assembled battery of this structure cannot effectively dissipate the radiant heat radiated from the unit cell 1 located in the middle. This is because the radiant heat emitted from the case of the unit cell 1 irradiates and heats the side surface of the adjacent unit cell.

In the assembled battery described in [1], as shown in FIG. 4, the heat radiating plate 2 is sandwiched between the unit cells 1. Heat sink 2
Has a heat radiation path for convection air between the two plates. Heat is conducted from the unit cell 1 to the plate.
The conducted heat is radiated to the air convection on the opposite surface.
In the assembled battery having this structure, the internal cells are cooled by the heat dissipation plate. However, in this battery pack, it is difficult to efficiently cool the unit cell with a heat sink. This is because the heat of the unit cell is transferred to the heat dissipation path via the plate and is cooled in the heat dissipation path. In order to effectively dissipate the heat of the cell from the plate to the heat dissipation path, it is important that the plate is in close contact with the surface of the cell over a wide area. This is because when the plate is in direct contact with the surface of the unit cell, the heat of the unit cell is effectively conducted to the plate directly without passing through the air layer between the plate and the battery case. However, it is actually very difficult to uniformly adhere the side surface of the prismatic unit cell to the heat sink over a wide area. This is because the surfaces of both the unit cell and the heat sink cannot be perfectly flat. If the unit cell and the heat sink have a slight unevenness, the unit cell and the heat sink cannot be adhered to each other over a wide area. Therefore, there is a drawback that heat cannot be efficiently conducted from the unit cell to the heat sink.

Further, the battery pack described in the publication is
Since the high thermal conductive sheet is sandwiched between the unit cells, it is difficult for this structure to adhere the thin high thermal conductive sheet to the surface of the unit cell in a large area. Therefore, there is a drawback that the heat conduction between the unit cell and the high thermal conductive sheet cannot be realized in a state close to ideal.

When manufacturing a battery, it is difficult to process the case surface into a perfect flat surface. Furthermore, if charging and discharging are repeatedly performed after manufacturing, it is extremely difficult to completely prevent the surface of the case from becoming non-planar due to the expansion force of the electrode plate. For this reason, it is difficult to bring the heat sink and the surface of the prismatic unit cell into close contact with each other in an ideal state to effectively conduct heat from the unit cell to the heat sink.

[0010] In order to more closely adhere adjacent cells to each other, an assembled battery in which a pressure spring is provided on a sandwiching plate sandwiching the cells on both sides has also been developed (JP-A-6-388).
No. 304 publication). The pressure spring presses the unit cells in the stacking direction to bring the unit cells into close contact. The unit cell can be pressed against the heat dissipation plate by utilizing the structure in which the pressure plate is provided with the pressure spring. However, even with this structure, it is difficult to widen the contact area between the unit cell and the heat sink. This is because the surfaces of the unit cell and the heat sink cannot be made completely flat. If the surfaces of the unit cell and the heat sink can be made to be completely flat, the unit cell can be pressed against the heat sink by the pressure spring of the sandwiching plate to bring them into close contact with each other. However, since both the unit cell and the heat sink cannot be made completely smooth, the contact area cannot be so large even if they are strongly pressed.

The present invention was developed for the purpose of closely adhering the unit cell and the heat sink in an ideal state. An important object of the present invention is to use the heat sink to generate heat from an internal unit cell. It is an object of the present invention to provide an assembled battery that can effectively dissipate heat and effectively prevent the deterioration of the battery performance of the internal battery.

[0012]

The assembled battery of the present invention comprises a plurality of unit cells 1 each having a rectangular outer shape, and a heat radiating plate 2 sandwiched between the unit cells 1 for radiating heat of the unit cells 1. , The sandwiching plates 3 for arranging the plurality of unit cells 1 and sandwiching both outer sides thereof and the sandwiching plates 3 on both sides are connected, and the plurality of unit cells 1 are stacked via the heat dissipation plate 2 and integrally connected. And a connecting part 4.

Further, in the assembled battery of the present invention, the heat radiating plate 2 having the elastically deforming convex portion 2A is sandwiched between the unit cells 1. The elastically deforming convex portion 2A forms the heat dissipation path 5 between the adjacent unit cells 1. Further, the elastically deforming convex portion 2A is provided in the unit cell 1
Has a flexibility of being deformed by being pressed by the sandwiched unit cells 1. The elastic deformation convex portion 2A is
When the sandwiching plate 3 is tightened by the connecting component 4, the sandwiching plate 3 is sandwiched and deformed by the unit cell 1. Elastically deforming convex portion 2A that deforms
Absorbs the deviation of the flatness of the surface of the cell 1 and the heat sink 2,
The heat sink 2 is brought into close contact with the side surface of the unit cell 1. The heat radiating plate 2 having the elastically deforming convex portion 2A is used together with a member that radiates heat from between the unit cells 1 and presses the heat radiating plate 2 against the side surface of the case 6 of the unit cell 1 in a large area.

[0014]

In the assembled battery of the present invention, the heat radiating plate 2 sandwiched between the unit cells 1 is provided with the elastically deforming convex portion 2A which is deformed by being sandwiched between the unit cells 1. The elastically deforming convex portion 2A is crushed by the unit cells 1 on both sides when the sandwiching plate 3 is tightened by the connecting component 4, and the heat sink 2 is brought into close contact with the surface of the unit cell 1.
In the elastically deforming convex portion 2A, the portion strongly pressed by the unit cell 1 is crushed thinner than the weakly pressed portion. The portion that strongly presses the elastic deformation convex portion 2A is the portion where the unit cell 1 and the heat dissipation plate 2 are in contact with each other. By crushing this portion thinly, the unit cell 1 and the heat dissipation plate 2 come into close contact with each other over a wider area. Therefore, the assembled battery of the present invention,
By tightening the connecting component 4, the unit cell 1 and the heat sink 2 can be brought into close contact with each other over a wide area, and the heat generated by the unit cell 1 is efficiently conducted to the heat sink 2. The heat dissipation plate 2 efficiently dissipates the heat conducted from the unit cell 1 from the heat dissipation path 5.

In the assembled battery of the present invention, the elastic deformation convex portion 2A is crushed and the heat sink 2 is brought into close contact with the surface of the unit cell 1, so that the case 6 of the unit cell 1 and the surface of the heat sink 2 are raised. It is not necessary to manufacture a flat surface with high precision. This means that
It is extremely convenient to use a thin metal plate or a plastic which is easily deformed for the case 6, so that the unit cells 1 can be mass-produced at low cost.

Further, the elastically deforming convex portion 2A is not only brought into close contact with the surface of the unit cell 1 to the heat dissipation plate 2 when manufacturing the assembled battery, but also when the assembled battery is repeatedly charged and discharged, The unit cell 1 is firmly attached to the heat sink 2. This is because even if the battery pack is repeatedly charged and discharged and the electrode plate of the unit cell 1 expands and the case 6 is deformed by this, the deformation of the case 6 is absorbed by the elastic deformation convex portion 2A. The prismatic unit cell 1 is deformed so that the central portion of the case 6 expands when the electrode plate expands. When the case 6 is deformed and a local portion on the surface of the case projects, the elastically deforming convex portion 2 located on the projecting portion
A is crushed. Thinly crushed elastically deformed protrusion 2A
Holds the surface of the case 6 in a pressed state and brings the heat dissipation plate 2 into close contact with the surface of the unit cell 1 while preventing the case 6 from expanding. In the assembled battery in this state, the expansion of the electrode plate is suppressed, and moreover, the surface of the unit cell 1 adheres to the heat dissipation plate 2 in a wide area. Therefore, no excessive internal stress acts on the electrode plate, and moreover, the heat dissipation plate 2 can be adhered to the surface of the unit cell 1 in a large area to efficiently dissipate heat.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. However, the examples described below exemplify the assembled battery for embodying the technical idea of the present invention, and the present invention does not specify the assembled battery to the following.

Further, in this specification, for easy understanding of the claims, the numbers corresponding to the members shown in the embodiments are referred to as "claims column", "action column", and "action column". It is added to the members shown in the section of "Means for Solving the Problems". However, the members shown in the claims are
It is by no means specific to the members of the examples.

The assembled battery shown in the perspective view of FIG. 5 and the exploded perspective view of FIG. 6 includes a plurality of cells 1 and a heat radiating plate 2 sandwiched between the cells 1 to radiate the heat of the cells 1. And a sandwiching plate 3 for arranging the plurality of cells 1 side by side and sandwiching both outer sides thereof, and the sandwiching plates 3 on both sides are connected to each other to dissipate the plurality of cells 1 from the heat dissipation plate 2.
And a connecting component 4 that is integrally laminated and is connected via the.

The unit cell 1 is a secondary battery such as a nickel-hydrogen battery, a nickel-hydrogen battery, or a lithium-ion battery. The unit cell 1 is obtained by inserting electrodes into a rectangular case 6 and sealing the case. The rectangular case 6 is made of plastic or metal. The case 6 of the unit cell 1 shown in the exploded view of FIG. 6 has a relatively thin rectangular shape for convenience of stacking.

The sandwiching plate 3 is a metal plate or a hard plastic plate, and has a rectangular shape wider than the unit cell 1, and the connecting component 4 is inserted into a portion protruding laterally from the unit cell 1 to be sandwiched. A through hole 3A is provided. In the assembled battery having this structure, which is sandwiched by four connecting parts 4, two through holes 3A through which the connecting parts 4 are inserted are provided on both sides.
Provide 4 in total. The sandwiching plate 3 is designed to have a strength and a thickness that do not deform even when the unit cells 1 are sandwiched by tightening the connecting components 4 inserted on both sides. As shown in FIG. 5, the sandwiching plate 3 may be coupled to the base plate 7 after the coupling component 4 is tightened to sandwich the unit cell 1.
To fix the sandwiching plate 3 to the base plate 7, for example, a slit that penetrates the base plate 7 is provided, and a set screw is inserted into this slit, and the tip of the set screw is provided on the lower surface of the sandwich plate 3. It can be fixed by inserting it into the screw hole. The slit extends in the direction of the connecting component 4, and is opened at a position where the set screw can be inserted even if the sandwiching plate 3 moves in the direction of the connecting component 4. The structure for connecting the sandwich plate 3 to the base plate 7 is, for example, the sandwich plate 3
It is also possible to adhere the lower end of the to the base plate 7 or to connect it via an L metal fitting (not shown).

The connecting part 4 is a shaft for connecting the sandwiching plates 3 on both sides, and male screws are provided at both ends thereof. Through hole 3 of sandwich plate 3 connected by connecting component 4
A is a stupid hole larger than the outer diameter of the connecting component 4. In the sandwiching plate 3 having this structure, the connecting component 4 is inserted into the through hole 3A, which is a stupid hole, and the nuts 10 are screwed into both ends of the shaft for connection. However, although not shown, if the connecting part is a screw rod and one of the through holes of the sandwiching plate is a screw hole into which the screw rod can be screwed, the tip of the screw rod is inserted into the screw hole and the connecting part is rotated to sandwich it. The attachment plates can also be connected. The connecting component of this structure can connect both sandwiching plates without using a nut. Further, as shown in FIG. 7, screw holes are provided at both ends of the intermediate rod 8 arranged between the sandwiching plates 3 without using the screw rod as the connecting part, and the sandwiching plate 3 is inserted into the screw holes of the intermediate rod 8. It is also possible to connect the sandwiching plate 3 by penetrating through and screwing the set screw 9. The connecting component of this structure has a feature that the sandwiching plates 3 on both sides can be connected at the same interval.

The heat dissipation plate 2 has an elastically deforming convex portion 2A. The elastically deforming convex portion 2A projects in the stacking direction of the unit cells 1 and forms the heat dissipation path 5 between the adjacent unit cells 1.
Further, the elastically deforming convex portion 2A has flexibility to be pressed and deformed by the sandwiched unit cell 1 when the sandwiching plate 3 is tightened by the connecting component 4. This is because the elastically deforming convex portion 2A that deforms absorbs the deviation of the flatness between the surfaces of the unit cell 1 and the heat dissipation plate 2, and causes the heat dissipation plate 2 to closely contact the side surface of the unit cell 1.

The heat radiating plate 2 shown in FIG. 6 has an elastically deforming convex portion 2A.
Is formed of a corrugated plate 2a, and a flat plate 2b is formed on one surface of the corrugated plate 2a.
Are stacked. The corrugated plate 2 a has the flexibility of being thinly crushed when sandwiched between the unit cells 1. The flat plate 2b is the corrugated plate 2
It has the flexibility of being deformed into a shape along the surface of the unit cell 1 when pressed by a. In the heat dissipation plate 2 shown in this figure, the corrugated plate 2a is attached to the unit cell 1 on one side, and the flat plate 2b is attached to the surface of the other unit cell 1 on the other side. Heat sink 2 in this figure
In the above, one flat plate 2b is arranged on one side of the corrugated plate 2a, but the flat plates 2b may be arranged on both sides of the corrugated plate 2a. The heat dissipation plate 2 in which the flat plate 2b is laminated on the corrugated plate 2a is the flat plate 2
b can be adhered to the surface of the cell 1 in a large area.

In the assembled battery of the present invention, the structure of the heat dissipation plate 2 is not limited to the combination of the flat plate 2b and the corrugated plate 2a. The heat radiating plate 2 shown in FIG. 8 is obtained by pressing a flat plate to obtain a large number of elastically deforming protrusions 2.
A is provided so as to project. As shown in FIG. 9, the elastically deforming convex portion 2A has a tip formed in a flat shape so as to come into contact with the surface of the unit cell 1 in a wide area. The elastically deforming convex portion 2A has the flexibility of being crushed when sandwiched between the unit cells 1.

The heat sink 2 is preferably aluminum,
Manufactured from metal plates such as copper and iron. The metal heat sink has good thermal conductivity and has the feature that it can effectively dissipate the heat of the single cell.
The elastically deforming convex portion 2A has the flexibility of being crushed and deformed when sandwiched between the unit cells 1. Metal heat sink 2
Can adjust the thickness of the elastic deformation convex portion 2A to adjust the strength of deformation. When the elastically deforming convex portion 2A is made thin, the elastic deforming convex portion 2A is deformed by a weak clamping force. The elastically deforming convex portion 2A has a shape that is easily deformed and a shape that is difficult to be deformed even if the same material and thickness are used. The elastically deforming convex portion 2A composed of the corrugated plate 2a is easily deformed, but the elastically deforming convex portion 2A composed of local protrusions is not easily deformed as shown in FIG. The elastically deformable convex portion that is easy to deform can be deformed even if it is thick, but the elastically deformable convex portion that is difficult to deform is made thin to facilitate deformation.

The elastically deformable convex portion 2A made of metal has a property of being restored to its original shape by cushion back when deformed. Therefore, the elastically deformable convex portion 2A made of metal has a feature that, in the crushed state, it is elastically pressed by the unit cell 1 to be held in a close contact state.

The assembled battery shown in FIG. 5 has a base plate on the bottom surface. However, the assembled battery of the present invention does not necessarily need to be provided with the base plate. In the assembled battery without the base plate, the flat plate of the heat dissipation plate is bent into an L shape as shown in FIGS. 6 and 8. The L-shaped bent portion is brought into contact with a device or a device to which the assembled battery is attached in a large area. This structure is a flat plate of a heat radiating plate and effectively radiates the heat of the assembled battery to the outside. Thereby, the heat dissipation effect can be further enhanced.

[0029]

The assembled battery of the present invention has an extremely simple structure and is characterized in that the heat inside the assembled battery can be effectively dissipated by the heat radiating plates sandwiched between the unit cells. That is, the assembled battery of the present invention is provided with an elastic deformation convex portion which is crushed and deformed when sandwiched between the unit cells in the heat dissipation plate. This is because the deformed convex portion is also used as a cushioning material and the heat dissipation plate is pressed against the surface of the unit cell to be brought into close contact therewith. The assembled battery of the present invention, which can efficiently dissipate heat from the internal cells, has a feature that it can effectively prevent the deterioration of the battery performance of the internal cells by charging and discharging with an excessive current.
This is because all the unit cells can efficiently dissipate heat. In particular, the assembled battery of the present invention has a feature that the heat sink can effectively radiate heat from the internal cells even when it is repeatedly charged and discharged many times, not to mention immediately after manufacturing, and can reduce the temperature rise. There is. The reason is that even if the cell case swells locally after repeated use, the deformation of the case is crushed and absorbed by the elastic deformation convex part, and the heat sink adheres to the surface of the cell in a large area. is there.

The assembled battery of the present invention which can effectively dissipate heat from the internal cells has the feature that the capacity of the internal cells can be prevented from decreasing. A curve C of FIG. 1 is a graph showing a temperature rise at the end of charging of each cell when the battery pack of the present invention shown in FIG. 5 is used, and a curve D is actually measured with respect to the nominal capacity of each cell. It is a graph which shows the ratio of a battery capacity. However, the unit cell is a nickel-hydrogen battery. The battery capacity indicated by the curve D is the same as the conventional assembled battery indicated by the curve B, in which a single battery is connected in series and fully charged at 0.2 C, and then discharged at 1/3 C for 100 charge / discharge cycles. It is a numerical value obtained by individually measuring the capacity of each unit cell after repeating the cycle. As shown in this graph, the assembled battery of the present invention has a feature that it can effectively prevent the capacity of the unit cell sandwiched in the center from decreasing as compared with the conventional assembled battery shown in FIG. . Further, FIG. 10 is a graph showing the cycle life of the battery pack of the present invention shown in FIG. 5 and the conventional battery pack. Also in this graph, the unit cell is a nickel-hydrogen battery. As shown in curve E of this graph,
The battery capacity of the conventional assembled battery gradually decreased after repeating charging and discharging about 300 times.
As shown by the curve F, the battery capacity does not decrease after 500 uses.

Further, the assembled battery of the present invention has a feature that even if the tightening force of the connecting parts is increased to some extent, an excessive pressing force does not act on the unit cell. This is because, in the assembled battery of the present invention, when the connecting parts are tightened and the heat radiating plate is sandwiched between the unit cells, the elastically deforming convex portions are crushed. As the connecting component is tightened more strongly, the elastic deformation convex portion of the heat dissipation plate is crushed more thinly and absorbed by the elastic deformation convex portion. Therefore, the assembled battery of the present invention is characterized in that even if the connecting parts are tightened to some extent, the unitary cell does not have an unreasonable clamping force, and the heat sink can be completely adhered to the unitary battery.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between temperature distribution and battery capacity of each stacked unit cell in an assembled battery.

FIG. 2 is a perspective view showing an example of a conventional assembled battery.

FIG. 3 is a perspective view showing an example of a conventional assembled battery.

FIG. 4 is a perspective view showing an example of a conventional assembled battery.

FIG. 5 is a perspective view of an assembled battery according to an embodiment of the present invention.

FIG. 6 is an exploded perspective view of an assembled battery according to an embodiment of the present invention.

FIG. 7 is a cross-sectional view showing another specific example of the connecting component according to the embodiment of the present invention.

FIG. 8 is a perspective view showing another specific example of the heat dissipation plate according to the embodiment of the invention.

9 is a cross-sectional view of the heat sink shown in FIG.

FIG. 10 is a graph showing the cycle life of the assembled battery.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Single cell 2 ... Heat dissipation plate 2A ... Elastic deformation convex part 2a ... Corrugated plate 2b ... Flat plate 3 ... Clamping plate 3A ... Through hole 4 ... Connection part 5 ... Heat dissipation path 6 ... Case 7 ... Base plate 8 ... Intermediate rod 9 ... Set screw

Claims (1)

[Claims] 1. A plurality of unit cells (1) having a rectangular outer shape,
A heat dissipation plate (2) sandwiched between the unit cells (1) to radiate the heat of the unit cells (1), and a sandwich plate (3) for arranging a plurality of the unit cells (1) and sandwiching both outer sides. And a connecting component (4) that connects the sandwiching plates (3) on both sides and stacks a plurality of cells (1) via the heat dissipation plate (2) and integrally connects them, The heat sink (2) protrudes in the stacking direction of the cells (1) to form a heat dissipation path (5) between the adjacent cells (1) and presses the sandwiched cells (1). Has an elastically deforming convex portion (2A) that is deformed by being deformed, and further, this elastically deforming convex portion (2A) is a unit cell (1) in a state where the sandwiching plate (3) is tightened by the connecting component (4). The elastically deforming convex part (2A) that is pinched and deformed by
An assembled battery characterized in that it is configured to be used together with a member that presses the heat dissipation plate (2) against the side surface of the case (6) of the unit cell (1).