JP5159425B2 - Battery module - Google Patents

Description

  The present invention relates to an assembled battery module incorporating a flat unit cell.

  Conventionally, in order to deal with a variety of load voltages and load capacities by using batteries, the assembled batteries are often configured by connecting the batteries in series, parallel, or a combination thereof. As a battery assembly method, a plurality of batteries are generally fixed with a tape, fixed with a heat shrinkable tube, or stored in a hard case. However, simply fixing it with tape, fixing it with a heat-shrinkable tube, or storing it in a hard case does not dissipate the heat generated by the heat generated by the battery itself and accumulates it, resulting in a short battery life. End up.

  In particular, in recent years, applications used for rapid charging and high-rate discharge have increased, and the battery temperature tends to be high, which is a cause of further shortening the life. In particular, when an assembled battery is configured so that the long side surfaces of flat cells are in contact with each other, there is almost no heat dissipation path other than tab leads, and the temperature of the battery located in the center is very high, compared to other batteries The lifetime is reached early, and as a result, the lifetime of the assembled battery is shortened.

For this reason, an air cooling method (Patent Document 1) is proposed in which a gap is formed between the single cells, and cooling is performed by flowing cooling air therethrough. Further, a water cooling system (Patent Document 2) in which a coolant is circulated between single cells has been proposed.
JP 2005-108750 A JP 2003-346924 A

However, these methods require a gap for circulating cooling air or coolant between the single cells, and the size of the assembled battery module increases accordingly.
In addition, when these types of assembled battery modules are used in moving bodies that are constantly subject to large impacts such as electric vehicles and aircraft, there is a gap between the single cells, which complicates the vibration resistance design and provides sufficient vibration resistance. It is difficult to get a structure.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an assembled battery module that is superior in heat dissipation and vibration resistance as compared with the prior art.

An assembled battery module according to the present invention includes a plurality of stacked flat unit cells, a carbon sheet disposed between the flat unit cells, and an outer package surrounding the assembled cell including the flat unit cells and the carbon sheet. The carbon sheet is bent at 90 ° at both ends in the width direction, and the outer case includes two upper and lower metal outer plates and two metal side plates. The two side plates are fixed to the exterior plate, the two side plates have fins formed on the outer surface and have a heat sink function, and the bent portions of the carbon sheets are in close contact with the metal side plates, The carbon sheet is characterized by high thermal conductivity in the width direction and low thermal conductivity in the thickness direction .

  ADVANTAGE OF THE INVENTION According to this invention, the assembled battery module excellent in heat dissipation and vibration resistance compared with the past can be provided.

Hereinafter, the assembled battery module of the present invention will be described in more detail.
As described above, in the assembled battery module of the present invention, the carbon sheet is disposed between the flat unit cell and the flat unit cell, and the carbon sheet is in contact with the outer case serving also as a heat sink.

  In the present invention, the carbon sheet is not particularly limited, but is preferably a carbon sheet having a high thermal conductivity in the width direction and a low thermal conductivity in the thickness direction. Generally, metal plates such as aluminum (thermal conductivity 100 to 250 W / mK) and copper (thermal conductivity 400 W / mK) have the same thermal conductivity in all directions, and therefore heat adjacent cells. . However, this carbon sheet has a different thermal conductivity depending on the crystal arrangement direction, and by laminating crystals in the thickness direction, the thermal conductivity in the width direction is very high, 200 to 1000 W / mK, and the thermal conductivity in the thickness direction The rate can be very low compared to the thermal conductivity in the width direction, ie 10 W / mK or less. Therefore, by using the carbon sheet, heat can be efficiently transferred to the exterior case without transferring much heat to the adjacent unit cells.

In the present invention, the carbon sheet is preferably sandwiched between double-sided adhesive low-hardness heat conductive sheets. By using the low-hardness heat conductive sheet, the thermal resistance due to slight unevenness of the flat unit cell can be reduced, heat dissipation can be improved, adhesion can be improved, and earthquake resistance can be improved.
In the present invention, it is preferable that a gap between the flat battery and the carbon sheet is filled with a heat conductive adhesive. By filling the heat conductive adhesive in this manner, the thermal resistance due to slight unevenness of the flat unit cell is reduced, the heat dissipation can be improved, the adhesion is improved, and the earthquake resistance is improved.
Further, since the carbon sheet is mainly made of carbon having a specific gravity smaller than that of metal, the carbon sheet can be reduced in weight as compared with the case where a metal plate is used.

  In this invention, it is preferable that the said carbon sheet is a carbon sheet which bonded metal foil to the surface. In general, carbon sheets have the disadvantage of being brittle to vibrations and shocks, but without damaging the good properties of the carbon sheet by laminating a metal foil with high thermal conductivity such as aluminum foil or copper foil on the surface. Thus, mechanical durability that can be sufficiently withstood in actual use can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2. Here, FIG. 1 is an example of the assembled battery module according to the present invention, and FIG. 2 is a development view of the assembled battery module. In addition, this invention is not limited only to the following embodiment.

  Reference numeral 1 in the figure denotes a flat unit cell (hereinafter simply referred to as a unit cell) laminated on both sides via a low-hardness heat conductive sheet 2 and 2 that is adhesive. Here, as the heat conductive sheets 2 and 2, low hardness silicone rubber having a hardness of 30 or less (measured by stacking two 6 mm thick sheets) was used. In addition, as a unit cell, a laminated pack type lithium ion storage battery having a rated capacity of 10 Ah having a length of 140 mm, a width of 80 mm, and a thickness of 10 mm was used, and seven of the storage batteries were connected in series to form a 24V-10Ah battery module. . Each unit cell 1 is provided with a positive electrode terminal 3 and a negative electrode terminal 4. Between the heat conductive sheets 2 and 2, the carbon sheet 5 bent at substantially right angles at both ends is disposed so as to be in close contact with the heat conductive sheets 2 and 2. In addition, the one heat conductive sheet 2 is arrange | positioned also between the uppermost single cell 1 and the metal exterior board 6a, and the lowermost single cell 1 and the metal exterior board 6b.

  The laminate in which the unit cell 1, the heat conductive sheet 2 and the carbon sheet 5 are laminated is surrounded by an upper exterior plate 6a, a lower exterior plate 6b, and two metal side plates 7a and 7b. The L-shaped portions bent at approximately 90 ° at both ends of the carbon sheet 5 are arranged so as to be in close contact with the side plates 7a and 7b having the fins 7 '. Three long holes (fixed holes) 8 are formed above and below the side plate 7, and the side plate 7 is fixed to the exterior plates 6 a and 6 b through the fixed holes 8 by fixing screws 9. The outer case 10 is assembled by inserting and fixing the outer plates 6a and 6b and the side plates 7a and 7b having a heat sink function into the fixing holes 8 provided in the side plates 7a and 7b.

Specific examples will be described below. However, the same reference numerals as those in FIGS. 1 and 2 are used as the reference numerals in the description.
Example 1
A carbon sheet 5 having a thickness of 1 mm is disposed between each unit cell 1, and each carbon sheet 5 is in contact with the side plates 7a and 7b of the exterior case 10 which also serves as a heat sink, and is sandwiched between the upper and lower exterior plates 6a and 6b. A single cell was fixed. The used carbon sheet 5 is a carbon sheet having a higher thermal conductivity in the width direction than in the thickness direction.

(Example 2)
The same carbon sheet 5 as in Example 1 having a thickness of 1 mm is disposed between each unit cell 1, and a double-sided adhesive low hardness thermal conductive sheet 2 is disposed between the unit cell 1 and the carbon sheet 5. The carbon sheet 5 is sandwiched so that the carbon sheets 5 are in close contact with each other. Fixed. In addition, a thermally conductive silicone rubber sheet was used as the double-sided adhesive low-hardness thermally conductive sheet 2.

(Example 3)
Between each unit cell 1, a carbon sheet 5 having a thickness of 1 mm and the same carbon sheet 5 as that of Example 1 bonded to both surfaces is arranged, and the unit cell 1 and the aluminum sheet are bonded to each other. An outer case 10 in which a double-sided adhesive low-hardness heat conductive sheet 2 is disposed between the carbon sheets 5 via an aluminum foil so that the carbon sheets 5 are in close contact with each other, and each carbon sheet 5 also serves as a heat sink. The unit cell 1 was fixed by being in contact with the side plates 7a and 7b and sandwiched between the upper and lower exterior plates 6a and 6b. Further, as the double-sided adhesive low-hardness heat conductive sheet 1, a heat conductive silicone rubber sheet was used.

(Comparative Example 1)
In Comparative Example 1, the same reference numerals are used for the same members in FIGS. 1 and 2 as the reference numerals of the respective members, but the carbon sheet is not used.
An aluminum plate having a thickness of 1 mm is disposed between each unit cell 1, and a double-sided adhesive low-hardness heat conductive sheet 2 is disposed between the unit cell 1 and the aluminum plate so that they are in close contact with each other. The aluminum plate was brought into contact with the side plates 7a and 7b of the outer case 10 also serving as a heat sink, and was sandwiched between the upper and lower outer plates 6a and 6b to fix the unit cell. In addition, a thermally conductive silicone rubber sheet was used as a double-sided adhesive low-hardness thermally conductive sheet.

(Comparative Example 2)
In Comparative Example 2, the same reference numerals are used for the same members in FIG. 1 and FIG. 2 for the members, but the carbon sheet and the aluminum plate are not used. That is, the assembled battery module of Comparative Example 2 does not include a carbon sheet or an aluminum plate between the single cells 1, and is sandwiched between the exterior plates 6 a and 6 b and the side plates 7 a and 7 b as the exterior case 10. Fixed.

(Test 1)
When the unit cells according to Examples 1, 2, and 3 and the unit cells according to Comparative Examples 1 and 2 were repeatedly charged and discharged under the following charging conditions and discharging conditions, the temperatures of the unit cells were measured. The result shown in 1 was obtained. However, the temperature of each unit cell was measured by attaching a thermocouple to the center of each unit cell.

Charging conditions: CC-CV 0.5CA, 29.4V, 0.05CA Cut-off
Discharge condition: CC 9.0CA, 21.0V Cut-off
From the following Table 1, the assembled battery module according to the present invention was able to keep the temperature of the cell at the center part low.

Further, in the single cells according to Examples 1, 2, and 3 and the single cells according to Comparative Examples 1 and 2, the capacity test was performed before and after the vibration test, and the change in capacity was measured. The results shown in Table 2 below were obtained. It was.
The vibration test and the capacity test were performed under the following conditions. Further, the capacity retention rate is a ratio of the capacity after vibration when the capacity before vibration is 100% for each assembled battery.

(Vibration conditions)
Standard: MIL-STD-810 FIGURE C-8
・ Power spectral density: 0.077 g ² / Hz
・ Direction: X direction, Y direction, Z direction
・ Time: 3 hours in each direction
(Capacity test conditions)
-Charging conditions: CC-CV 0.5CA, 29.4V, 0.05CA Cut-off
-Discharge condition: CC 0.5CA, 21.0V Cut-off
From Table 2 below, it was found that the assembled battery module of the present invention has a sufficient capacity and vibration-proof structure with little decrease in capacity.

  As described above, since the carbon sheet 5 is disposed between the flat unit cell 1 and the flat unit cell 1 and the carbon sheet 5 is in contact with the exterior case that also serves as a heat sink, heat dissipation is improved and weight reduction is achieved. Each carbon sheet is made possible by arranging a double-sided low-hardness heat conductive sheet 2 or a heat conductive adhesive between the flat unit cell 1 and the carbon sheet 5 so that they are in close contact with each other. By fixing 5 so as to be in contact with the outer case that also serves as a heat sink, heat dissipation and earthquake resistance were improved. In addition, the carbon sheet 5 is weak and brittle, so it is easily damaged by vibration. However, the carbon sheet 5 is completely or almost completely damaged by vibration by being sandwiched between the low-hardness heat conductive sheets 2 or by sticking an aluminum foil on the surface. It can be lost.

Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.
Furthermore, in Example 2 above, instead of the double-sided adhesive low-hardness heat conductive sheet, a carbon sheet may be sandwiched using a heat conductive adhesive, and the unit cell and the carbon sheet may be bonded to each other. The effect of can be obtained.
Hereinafter, the invention described in the scope of claims of the present application will be appended.
[1] An assembled battery module, wherein a carbon sheet is disposed between a flat unit cell and the flat unit cell, and the carbon sheet is in contact with an outer case serving also as a heat sink.
[2] The assembled battery module according to [1], wherein the carbon sheet is sandwiched between two-sided adhesive low-hardness heat conductive sheets.
[3] The assembled battery module according to [1] or [2], wherein a gap between the flat battery and the carbon sheet is filled with a heat conductive adhesive.
[4] The assembled battery module according to any one of [1] to [3], wherein the carbon sheet is a carbon sheet having a metal foil bonded to a surface thereof.
[5] The assembled battery module according to any one of [1] to [4], wherein the carbon sheet is a carbon sheet having a high thermal conductivity in the width direction and a low thermal conductivity in the thickness direction.

FIG. 1 is a schematic perspective view of an assembled battery module according to the first embodiment of the present invention. FIG. 2 is a development view of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Single cell, 2 ... Low-hardness heat conductive sheet, 3 ... Positive electrode terminal, 4 ... Negative electrode terminal, 5 ... Carbon sheet, 6a, 6b ... Exterior board, 7a, 7b ... Side plate, 8 ... Fixing hole, 9 ... Fixing Screw, 10 ... exterior case.

Claims (2)

A plurality of stacked flat cells,
A carbon sheet disposed between the flat cells,
An assembled battery module comprising an outer case surrounding the assembled battery including the flat cell and the carbon sheet;
The carbon sheet is bent at 90 ° at both ends in the width direction,
The outer case includes two upper and lower metal outer plates and two metal side plates, the two side plates are fixed to the outer plate, and the two side plates have fins formed on the outer surface to provide a heat sink function. Have
The bent portions of the carbon sheet are in close contact with the metal side plates,
The assembled battery module , wherein the carbon sheet has a high thermal conductivity in the width direction and a low thermal conductivity in the thickness direction . The assembled battery module according to claim 1 , wherein the carbon sheet is a carbon sheet having a metal foil bonded to a surface thereof.

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