JP2015138646A - Battery module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a structure having highly efficient heating/heat radiation properties in a battery module including a battery pack formed by assembling multiple cells, having a heating function.SOLUTION: A battery module 100 includes: a battery pack 30 formed by assembling multiple cells; a heating part H1 formed by planarly distributing filamentous heating elements (heating wires 51) along an outer surface (for example, a bottom surface) of the battery pack 30, where solid heat conduction materials are interposed between mutual heating elements; and a heat exchange part H2 which is located at the outer side relative to the heating part H1 when viewed from the outer surface and coming into contact with a fluid thereby exchanging heat.

Description

  The present invention relates to a battery module including an assembled battery formed by assembling batteries and a heating function.

  As secondary batteries with excellent energy density, for example, lithium ion batteries, sodium sulfur batteries, and nickel metal hydride batteries are known, but in recent years, secondary batteries have a strong advantage of nonflammability in addition to high energy density. As such, molten salt batteries using a molten salt as an electrolyte have attracted attention (see Patent Document 1 and Non-Patent Document 1). Further, since the molten salt battery has a wide operating temperature range in addition to nonflammability, it is suitable for forming an assembled battery by concentrating a large number of batteries, and thus a compact assembled battery can be formed.

  Therefore, an assembled battery formed by assembling molten salt batteries is expected to be used for hybrid vehicles (HEV, PHEV) and electric vehicles (EV), in addition to power storage applications in medium-scale power networks and homes. The operating temperature range of the molten salt battery is, for example, 57 ° C. to 190 ° C. From the viewpoint of stability of electrical characteristics, battery cycle life, temperature durability of the electrode portion, and the like, a more preferable temperature is, for example, 90 It is considered to be around degrees. In order to obtain such a temperature, a heater is used.

JP 2009-67644 A

"SEI WORLD" March 2011 issue (VOL. 402), Sumitomo Electric Industries, Ltd.

However, providing power for heating from the outside or from the battery itself to the battery, which is a source for supplying power to the outside, lowers the overall power generation efficiency. Therefore, it is preferable that heating can be performed as efficiently as possible.
On the other hand, even if the heater is stopped or kept warm after being heated by the heater, if the self-heating of the molten salt battery due to charging / discharging is increased by a large current, the temperature may be much higher than about 90 degrees. Therefore, in addition to the heating function, a heat dissipation function is also required. Since such heating / heat radiation relates to the performance and life of the battery and the power consumption for heating, an efficient heating / heat radiation function is desired.

  In view of such a problem, an object of the present invention is to provide a battery module having a heating function in an assembled battery formed by assembling a plurality of batteries, and to have a structure that is efficient for both heating and heat dissipation.

  The battery module of the present invention is formed by assembling a plurality of batteries and a linear heating element distributed in a plane along the outer surface of the assembled battery. A heating unit in which a heat conductive material is interposed, and a heat exchange unit that is located outside the heating unit when viewed from the outer surface and exchanges heat by contacting with a fluid are provided.

  According to the present invention, it is possible to provide a battery module that is efficient for both heating and heat dissipation.

1 is a schematic diagram showing in principle the basic structure of a power generation element in a molten salt battery. It is a cross-sectional view which shows simply the laminated structure of a molten salt battery main body (main-body part as a battery). It is a perspective view which shows the outline of the external appearance of one cell when a molten salt battery main body is accommodated in a battery container. It is a perspective view of the battery module which concerns on 1st Embodiment. It is a perspective view which shows a heating and a heat exchange unit before attaching to an assembled battery container. It is a perspective view which shows only a heating and a heat exchange unit. It is the VII-VII sectional view taken on the line in FIG. It is the figure which expanded a part in FIG. It is sectional drawing which shows only the characteristic part of the battery module which concerns on 2nd Embodiment. It is sectional drawing which shows only the characteristic part of the battery module which concerns on 3rd Embodiment. It is sectional drawing which shows only the characteristic part of the battery module which concerns on 4th Embodiment.

[Summary of Embodiment]
The gist of the embodiment of the present invention includes at least the following.

  (1) This battery module is formed by assembling a plurality of batteries together with a linear heating element distributed along the outer surface of the assembled battery, and a solid state between the heating elements. And a heat exchanging unit that is located outside the heating unit as viewed from the outer surface and exchanges heat by contacting the fluid.

In the battery module configured as described in (1) above, the heating unit is positioned closer to the assembled battery than the heat exchange unit. Therefore, when heating by energizing the heating unit, the assembled battery can be quickly heated. In addition, if a high temperature fluid is supplied to a heat exchange part, it is also possible to heat up or hold a battery pack from a heat exchange part.
On the other hand, when energization of the heating unit is stopped and heat dissipation is promoted by the heat exchanging unit, the heat of the assembled battery can be efficiently conveyed to the heat exchanging unit by the heating element and the heat conducting material between them. Moreover, since the heat exchange part is outside the heating part as viewed from the outer surface of the assembled battery, it is suitable for dissipating heat without trapping heat.

(2) In the battery module of (1), the heating unit and the heat exchange unit are integrally formed as a heating / heat exchange unit, and the heating element is formed in a groove formed on an end surface closer to the outer surface. May be buried.
In this case, the non-grooved portion (the so-called bank portion) between the grooves serves as a heat conductive material, contributing to the uniform distribution of heat during heating and contributing to the promotion of heat carry-out during heat dissipation.

(3) Moreover, the battery module of (1) WHEREIN: The said heat generating body may be embed | buried under the groove | channel formed in the outer surface of the assembled battery container which accommodates the said assembled battery.
In this case, the non-groove portion on the outer surface of the assembled battery container between the grooves serves as a heat conductive material, contributing to uniform heat distribution during heating, and promoting heat carry-out during heat dissipation.

(4) Moreover, the battery module of (1) WHEREIN: The said heat exchange part may be formed of the several fin or protrusion.
In this case, due to the formation of the fins or protrusions, the total area of the tip surfaces thereof becomes smaller than when the entire surface is flat. Accordingly, it is possible to suppress the amount of heat that escapes to the outside through the heat exchange unit during heating.

(5) In the battery module of (4), the heating element may be mounted so as to enter between the plurality of fins or protrusions and press against the root.
In this case, the heating element can be held closer to the assembled battery by utilizing the space between the fins or the protrusions. Therefore, it is not necessary to process the groove as in the case where the heating element is embedded.

(6) Moreover, the battery module in any one of (1)-(3) WHEREIN: The said heat exchange part may have a channel | path which lets a liquid pass only to one direction inside.
In this case, it is possible to quickly dissipate heat by flowing the liquid. In addition, if the liquid is not flowed, its heat capacity contributes to heat retention compared to gas.

(7) Moreover, in the battery module according to any one of (1) to (6), the battery is, for example, a molten salt battery using a molten salt as an electrolyte.
In order to operate the molten salt battery, it is necessary to melt the electrolyte, and it is preferable to maintain the temperature at, for example, about 90 ° C. for stable operation. The battery module is suitable for maintaining such temperature.

[Details of the embodiment]
<Basic structure of molten salt battery>
FIG. 1 is a schematic diagram showing in principle the basic structure of a power generation element in a molten salt battery. In the figure, the power generation element includes a positive electrode 1, a negative electrode 2, and a separator 3 interposed therebetween. The positive electrode 1 is composed of a positive electrode current collector 1a and a positive electrode material 1b. The negative electrode 2 includes a negative electrode current collector 2a and a negative electrode material 2b.

The material of the positive electrode current collector 1a is, for example, an aluminum nonwoven fabric (wire diameter: 100 μm, porosity: 80%). The positive electrode material 1b is a mixture of, for example, NaCrO ₂ as a positive electrode active material, acetylene black, PVDF (polyvinylidene fluoride), and N-methyl-2-pyrrolidone at a mass ratio of 85: 10: 5: 100. It is a thing. And what was kneaded in this way is filled in the positive electrode collector 1a of an aluminum nonwoven fabric, and after drying, it presses at 100 Mpa, and it forms so that the thickness of the positive electrode 1 may be set to about 1 mm.
On the other hand, in the negative electrode 2, an Sn—Na alloy containing, for example, tin as a negative electrode active material is formed on the aluminum negative electrode current collector 2a by plating.

  The separator 3 interposed between the positive electrode 1 and the negative electrode 2 is obtained by impregnating a glass non-woven fabric (thickness 200 μm) or a polyolefin sheet (thickness 50 μm) with a molten salt as an electrolyte. This molten salt is, for example, a mixture of 56 mol% NaFSA and 44 mol% KFSA (potassium bisfluorosulfonylamide), and has a melting point of 57 ° C. At a temperature equal to or higher than the melting point, the molten salt melts and becomes an electrolytic solution in which high-concentration ions are dissolved, and touches the positive electrode 1 and the negative electrode 2. Moreover, this molten salt is nonflammable. The operating temperature range of this molten salt battery is 57 ° C to 190 ° C, and a particularly preferable temperature range is around 90 ° C.

In addition, although the material, component, and numerical value of each part mentioned above are suitable examples, it is not limited to these.
For example, in addition to the above, a mixture of NaFSA and LiFSA, KFSA, RbFSA or CsFSA is also suitable as the molten salt. In addition, other salts composed of organic cations and the like may be mixed. In general, (a) a mixture containing NaFSA, (b) a mixture containing NaTFSA, and (c) a mixture containing NaFTA are suitable as the molten salt. . It is also possible to mix two or more of (a) to (c). In these cases, since the molten salt of each mixture has a relatively low melting point, a state in which high-concentration ions are dissolved with a small amount of heating can be realized, and the molten salt battery can be operated.

  In the above example, the molten salt battery in which the electrolyte is solidified at a room temperature of about 20 ° C. has been described, but other than this, for example, NaFSA and Py13FSA (N-methyl-N-propylpyrrolidinium FSA) Can be applied as an electrolytic solution / electrolyte having a melting point lower than 57 ° C., for example, a molten state even at a room temperature of about 20 ° C. However, even in this case, it is necessary to raise the temperature to a particularly preferable temperature range.

<Specific structure of molten salt battery>
Next, a more specific configuration of the power generation element of the molten salt battery will be described. FIG. 2 is a cross-sectional view schematically showing a laminated structure of the molten salt battery main body (main body portion as a battery) 10.
In FIG. 2, a plurality (six are shown) of rectangular flat plate-like negative electrodes 2 and a plurality (five are shown) of rectangular flat plates each accommodated in a bag-like separator 3 are shown. The positive electrodes 1 face each other and are stacked in the vertical direction in FIG. 2, that is, in the stacking direction, forming a stacked structure.

  The separator 3 is interposed between the positive electrode 1 and the negative electrode 2 adjacent to each other. In other words, the positive electrode 1 and the negative electrode 2 are alternately stacked via the separator 3. For example, 20 positive electrodes 1 and 21 negative electrodes 2 and 20 separators 3 as “bags”, but 40 intervening between positive electrodes 1 and 2 are actually stacked. is there. The separator 3 is not limited to a bag shape, and may be 40 separated.

  In FIG. 2, the separator 3 and the negative electrode 2 are drawn so as to be separated from each other, but they are in close contact with each other when the molten salt battery is completed. Naturally, the positive electrode 1 is also in close contact with the separator 3. In addition, the vertical and horizontal dimensions of the positive electrode 1 are smaller than the vertical and horizontal dimensions of the negative electrode 2 in order to prevent the generation of dendrites, and the outer edge of the positive electrode 1 passes through the separator 3. Thus, it faces the peripheral edge of the negative electrode 2.

<One form of cell>
The molten salt battery main body 10 configured as described above constitutes one physical cell by being housed in a rectangular parallelepiped battery container made of, for example, an aluminum alloy.
FIG. 3 is a perspective view showing an outline of the appearance of one cell (molten salt battery) 20 when the molten salt battery main body 10 is accommodated in the battery container 11x. In addition, from each of the positive electrode 1 and the negative electrode 2 in FIG. 2, the terminals 1t and 2t are pulled out of the battery container 11x while maintaining electrical insulation from the battery container 11x. The terminals 1t and 2t are provided on a lid 11a that seals the battery case 11x. In addition to the terminals 1t and 2t, the lid 11a is provided with a safety valve for releasing pressure when the internal atmospheric pressure rises excessively, but the illustration is omitted here. An assembled battery can be formed by arranging a plurality of such cells 20.

<< Battery Module: First Embodiment >>
Next, a first embodiment of the battery module will be described.
FIG. 4 is a perspective view of the battery module 100. An assembled battery 30 in which a plurality of cells 20 (eight in this example) are assembled side by side is housed in an assembled battery container 40 that is a rectangular parallelepiped outer box. The illustrated assembled battery container 40 shows a state in which the lid of the top plate is removed. The material of the assembled battery container 40 is, for example, an aluminum alloy.

  In FIG. 4, three directions orthogonal to each other are assumed to be X, Y, and Z. That is, the rectangular short side direction of the assembled battery container 40 in plan view is the X direction, the long side direction is the Z direction, and the height direction is the Y direction. On the bottom surface of the assembled battery container 40, a heating / heat exchanging unit 50 in which a heating unit and a heat exchanging unit are combined is attached. In the heating / heat exchange unit 50, the upper part in the Y direction is the heating part H1, and the remaining lower part is the heat exchange part H2.

  FIG. 5 is a perspective view showing the heating / heat exchange unit 50 before being attached to the assembled battery container 40. The heating / heat exchange unit 50 is attached to the bottom surface 40b of the assembled battery container 40 by, for example, screwing.

  FIG. 6 is a perspective view showing only the heating / heat exchange unit 50. In FIG. 6, the heating part H1 occupying the upper end surface side of the heating / heat exchange unit 50 is configured by embedding a linear heating wire 51 serving as a heating element in a groove formed on the upper end surface. Yes. The heating wire 51 is embedded so as to be distributed in a planar shape (XZ plane) along the bottom surface 30b (FIG. 5) of the assembled battery 30 and the bottom surface 40b (FIG. 5) of the assembled battery container 40. Terminal portions 51t1 and 51t2 of the heating wire 51 are led out to the outside. By energizing between these terminal portions 51t1 and 51t2, the heating wire 51 becomes a heating element. Moreover, the heat exchange part H2 which is the remaining part except the heating part H1 among the heating / heat exchange units 50 is configured by a large number of radiating fins 50f parallel to the YZ plane of the drawing.

  That is, the heating part H1 and the heat exchanging part H2 are integrally formed as the heating / heat exchanging unit 50, and in the groove formed on the end surface (upper surface) closer to the outer surface (bottom surface 30b) of the assembled battery 30, the heating element As a result, the heating wire 51 is embedded.

  7 is a cross-sectional view taken along line VII-VII in FIG. FIG. 8 is an enlarged view of a part of FIG. As shown in FIG. 8, the heating wire 51 has a central conductor 51a such as nichrome and a covering portion 51b made of a heat-resistant insulating material (for example, a glass tube) around it. The heating wire 51 is embedded in the groove 50g, and is adhesively fixed to the groove 50g by a resin sealing material 52.

  Returning to FIG. 7, in the heating part H <b> 1, a non-groove part 50 d that is a solid (aluminum alloy) is interposed between the adjacent grooves 50 g as a heat conductive material. Further, when viewed from the bottom surface 30b of the assembled battery 30, the heat exchanging portion H2 is located outside the heating portion H1, and exerts an air cooling effect by forcibly passing air between the radiating fins 50f. Conversely, if a high-temperature fluid such as hot air is passed, it can also be used for heating or heat insulation. Such hot air may be prepared independently, but waste heat of other devices can also be used.

In the battery module 100 configured as described above, the heating unit H1 is positioned closer to the assembled battery 30 than the heat exchange unit H2. Therefore, the temperature of the assembled battery 30 can be quickly raised during heating by energizing the heating part H1. In addition, if a high temperature fluid is supplied to the heat exchange part H2, the assembled battery 30 can also be heated up or heat-retained from the heat exchange part H2.
On the other hand, when energization to the heating part H1 is stopped and heat dissipation is promoted by the heat exchanging part H2, the heating battery (heating wire 51) and the heat conduction material (non-grooved part 50d) between them heat the assembled battery 30. Heat can be efficiently transferred to the heat exchange part H2. Moreover, since the heat exchange part H2 is outside the heating part H1 when viewed from the outer surface of the assembled battery 30, it is suitable for dissipating heat without trapping heat.
Therefore, it is possible to provide a battery module that is efficient for both heating and heat dissipation.

Further, the non-groove portion 50d between the two adjacent grooves 50g serves as a heat conductive material, which contributes to uniform distribution of heat during heating and contributes to promotion of heat carry-out during heat dissipation.
That is, when the non-groove portion 50d is interposed, when the heating wire 51 is a heating element by energization, the heat distribution is less concentrated only on the heating element, and the bottom surface 40b ( Contributes to transferring heat to Fig. 5) as evenly as possible. Further, when energization is stopped, that is, during heat radiation, all of the heat of the assembled battery 30, the heat of the assembled battery container 40, and the heat remaining in the heating wire 51 are easily carried out to the radiation fins 50f.

Further, the formation of the radiation fins 50f reduces the total area of the front end surfaces (lower end surfaces) as compared to the case where there are no radiation fins and the entire surface is a solid plane. Therefore, it is possible to suppress the amount of heat that escapes to the outside (mounting base 60) via the heat exchange part H2 during heating.
In the above embodiment, the heat radiating fins 50f are illustrated, but the shape of the heat exchange part H2 is not limited to “fins”. For example, a large number of columnar protrusions may be formed instead of the fins.
In the first embodiment, the heating unit H1 is in direct contact with the bottom surface 40b (FIG. 5) of the assembled battery container 40, but between them, a TIM (Thermal Interface Material) such as grease or an electric heating sheet is used. May be sandwiched.

<< Battery Module: Second Embodiment >>
FIG. 9 is a cross-sectional view showing only the characteristic part of the battery module 100 according to the second embodiment. In this figure, in this case, the difference from the first embodiment is that the heating wire 51 is embedded in the bottom surface 40b of the assembled battery container 40, and that the heat exchange part H2 is separated from the heating part H1. It is a point that exists. That is, in this case, what constitutes the heating part H1 is the heating wire 51 embedded in the bottom surface 40b of the assembled battery container 40, and the non-groove part 40d between the grooves is a heat conducting material. . Even with such a configuration, the same effects as those of the first embodiment can be obtained.

<< Battery Module: Third Embodiment >>
FIG. 10 is a cross-sectional view showing only the characteristic part of the battery module 100 according to the third embodiment. In this figure, in this case, the difference from the first embodiment is that the heating wire 51 having the same distribution as in FIG. 6 is not embedded in the groove, but is inserted between the adjacent radiation fins 50f and pushed to the root. It is a point to wear so as to hit. The folded portion of the heating wire 51 may be folded into another groove by providing a notch in the heat radiating fin 50f where necessary. If the heating wire 51 is fixed between the heat radiation fins 50f with an adhesive, for example, it can be stably held. The heating part H1 in this case is configured by the heating wire 51 and the non-groove part 50d (a part of the base of the heat radiation fin 50f) between the adjacent heating wires.
In the case of this embodiment, there exists an advantage that the process which provides the groove | channel for embedding the heating wire 51 becomes unnecessary.

<< Battery Module: Fourth Embodiment >>
FIG. 11 is a cross-sectional view showing only the characteristic part of the battery module 100 according to the fourth embodiment. In this figure, in this case, the difference from the first embodiment is that the space where the heat dissipating fins 50f are present is closed on the cross-sectional view and is a passage through which liquid passes only in one direction (Z direction). .
In this case, it is possible to quickly dissipate heat by flowing the liquid. In addition, if the liquid is not flowed, its heat capacity contributes to heat retention compared to gas.

<Others>
In each of the above embodiments, the example in which the heating unit H1 is provided along the bottom surface of the assembled battery 30 (and the bottom surface of the assembled battery container 40) has been described, but it may be provided on the outer surface other than the bottom surface. For example, the heating unit H1 can be provided along the outer surface of the assembled battery 30 (the outer surface of the assembled battery container 40). However, the upper surface of the assembled battery container 40 is unsuitable in terms of heat conduction efficiency.

In addition, in each said embodiment, although the battery module 100 using a molten salt battery was demonstrated, a battery is not limited to a molten salt battery.
For example, since a sodium-sulfur battery is in a higher operating temperature range (300 ° C. to 350 ° C.), heating / heat radiation is necessary, and a similar battery module can be configured.
In addition, the lithium ion battery basically operates at normal temperature, but for example, heating may be required for stable use in a cold region where the temperature is below -20 ° C. Conversely, if it exceeds 80 ° C., heat dissipation is required. Therefore, the same battery module can be applied to the lithium ion battery.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Positive electrode 1a Positive electrode collector 1b Positive electrode material 1t Terminal 2 Negative electrode 2a Negative electrode collector 2b Negative electrode material 2t Terminal 3 Separator 10 Molten salt battery main body 11a Lid 11x Battery container 20 Cell (molten salt battery)
30 assembled battery 30b bottom surface 40 assembled battery container 40b bottom surface 40d non-grooved portion 50 heating / heat exchange unit 50d non-grooved portion 50f radiating fin 50g groove 51 heating wire 51a central conductor 51b covering portion 51t1, 51t2 termination portion 52 sealing material 60 mounting base 100 Battery module H1 Heating part H2 Heat exchange part V Space

Claims (7)

An assembled battery formed by assembling a plurality of batteries;
A heating unit in which linear heating elements are distributed in a planar shape along the outer surface of the assembled battery, and a solid heat conductive material is interposed between the heating elements,
A heat exchanging unit that is outside the heating unit as seen from the outer surface and exchanges heat by contacting a fluid;
Battery module equipped with.   2. The battery module according to claim 1, wherein the heating unit and the heat exchange unit are integrally formed as a heating / heat exchange unit, and the heating element is embedded in a groove formed on an end surface closer to the outer surface. .   The battery module according to claim 1, wherein the heating element is embedded in a groove formed on an outer surface of an assembled battery container that houses the assembled battery.   The battery module according to claim 1, wherein the heat exchange part is formed by a plurality of fins or protrusions.   The battery module according to claim 4, wherein the heating element is mounted so as to enter between the plurality of fins or protrusions and press against the root.   The said heat exchange part is a battery module of any one of Claims 1-3 which has the channel | path which lets a liquid pass only to one direction inside.   The battery module according to any one of claims 1 to 6, wherein the battery is a molten salt battery using a molten salt as an electrolyte.

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