JP7453162B2 - Heat transfer suppression sheet for assembled batteries and assembled batteries - Google Patents

Description

The present invention relates to a heat transfer suppressing sheet for an assembled battery, which is suitably used in an assembled battery that serves as a power source for an electric motor that drives an electric vehicle or a hybrid vehicle, and an assembled battery using the heat transfer suppressing sheet for an assembled battery, for example. .

In recent years, from the viewpoint of environmental protection, development of electric vehicles or hybrid vehicles driven by electric motors has been actively promoted. This electric vehicle, hybrid vehicle, or the like is equipped with an assembled battery in which a plurality of battery cells are connected in series or in parallel to serve as a power source for a driving electric motor.

These battery cells mainly use lithium-ion secondary batteries, which have higher capacity and higher output than lead-acid batteries or nickel-metal hydride batteries, but internal short circuits and overcharging of the batteries can cause When thermal runaway occurs in one battery cell (that is, in the case of "abnormality"), heat propagates to other adjacent battery cells, which may cause thermal runaway in other battery cells.

For example, Patent Document 1 discloses a power storage device that can realize effective heat insulation between a plurality of power storage elements such as a lithium ion secondary battery. In the power storage device described in Patent Document 1, a first plate material and a second plate material are arranged between a first power storage element and a second power storage element that are adjacent to each other. Further, a low thermal conductivity layer, which is a layer of a substance having a lower thermal conductivity than the first plate material and the second plate material, is formed between the first plate material and the second plate material.

In the power storage device according to Patent Document 1 configured as described above, radiant heat directed from the first power storage element to the second power storage element or radiant heat directed from the second power storage element to the first power storage element is transmitted to the first plate material and the second power storage element. Interrupted by plate material. Further, the transfer of heat from one of these two plate materials to the other is suppressed by the low thermal conductivity layer.

However, since the above power storage device only has a heat insulating layer between the first power storage element and the second power storage element, it is not possible to effectively cool the battery cells that generate heat during charge/discharge cycles. Ta.

Therefore, Patent Document 2 proposes a heat absorbing sheet for assembled batteries that can cool each battery cell during normal use while suppressing the propagation of heat between each battery cell during abnormal conditions. The heat absorbing sheet described in Patent Document 2 contains two or more kinds of substances having different dehydration temperatures. At least one of the two or more substances is configured to be dehydrated during normal use of the battery cell, and the other at least one is configured to be dehydrated when the battery cell is abnormal. There is.

JP 2015-211013 Publication Japanese Patent Application Publication No. 2019-175806

By the way, when performing a charge/discharge cycle on assembled battery cells (in other words, during "normal use"), in order to fully demonstrate the charge/discharge performance of the battery cells, the temperature of the battery cell surface must be maintained at a predetermined level. It is necessary to maintain the temperature below this value (for example, below 150°C).
Further, when an abnormal situation occurs in which the battery cell reaches a temperature of 200° C. or higher, for example, it is necessary to effectively cool the battery cell.
As described above, there has been a recent demand for further improvements in heat transfer suppressing means that can maintain the temperature of the battery cell surface during normal use and effectively cool the battery cell surface during abnormal high-temperature situations.

The present invention has been made in view of the above-mentioned problems, and is used in an assembled battery in which a plurality of battery cells are connected in series or in parallel, and is used to suppress the propagation of heat between each battery cell in the event of an abnormality. An object of the present invention is to provide a heat transfer suppressing sheet for an assembled battery and an assembled battery that can cool each battery cell during use.

The above object of the present invention is achieved by the following configuration [1] related to a heat transfer suppressing sheet for an assembled battery.

[1] A heat transfer suppression sheet for an assembled battery, which is used in an assembled battery in which a plurality of battery cells are connected in series or parallel, and is interposed between the battery cells,
A heat insulating material containing at least one of inorganic particles and inorganic fibers;
a covering material that covers at least a portion of the heat insulating material;
having a concave portion and a convex portion on at least one of the surface of the heat insulating material facing the covering material and the surface of the covering material facing the heat insulating material;
A heat transfer suppressing sheet for an assembled battery, wherein a gap is formed between the heat insulating material and the covering material.

Further, preferred embodiments of the present invention relating to the heat transfer suppressing sheet for assembled batteries relate to the following [2] to [12].

[2] The heat insulating material has a concave portion and a convex portion on the surface facing the coating material,
The heat transfer suppression sheet for an assembled battery according to [1], wherein the gap is formed between the recess and the covering material.

[3] The heat transfer suppression sheet for an assembled battery according to [2], wherein the convex portion of the heat insulating material and the covering material are bonded to each other.

[4] The covering material has a concave portion and a convex portion on the surface facing the heat insulating material,
The heat transfer suppression sheet for an assembled battery according to [1], wherein the gap is formed between the recess and the heat insulating material.

[5] The heat transfer suppression sheet for an assembled battery according to [4], wherein the convex portion of the covering material and the heat insulating material are bonded to each other.

[6] The heat insulating material has a concave portion and a convex portion on the surface facing the coating material,
The covering material has a concave part and a convex part on a surface facing the heat insulating material,
The heat transfer suppression sheet for an assembled battery according to [1], wherein the gap is formed between the recess of the heat insulating material and the recess of the coating material.

[7] The heat transfer suppression sheet for an assembled battery according to [6], wherein the convex portion of the heat insulating material and the convex portion of the coating material are bonded to each other.

[8] The heat transfer suppressing sheet for an assembled battery according to any one of [1] and [4] to [6], wherein the covering material is composed of an embossed polymer film or metal plate.

[9] The heat transfer suppressing sheet for an assembled battery according to any one of [1] to [8], wherein the void portion communicates with the outside of the heat insulating material and the covering material.

[10] The void portion is sealed at a temperature of less than 60°C,
The coating material according to any one of [1] to [8], wherein the coating material is configured to form a communication port that communicates the void portion with the outside of the coating material at a temperature of 60° C. or higher. Heat transfer suppression sheet for assembled batteries.

[11] The heat insulating material and the coating material, or the coating materials are bonded together using an adhesive that melts at a temperature of 60° C. or higher, and the adhesive melts in stages in multiple areas as the temperature increases. The heat transfer suppressing sheet for an assembled battery according to [10], wherein a plurality of adhesives having mutually different melting temperatures are used in the plurality of regions so that the adhesives melt at a temperature of about 100%.

[12] The heat insulating material and the coating material, or the coating materials are bonded together using an adhesive that melts at a temperature of 60°C or higher, and the adhesive melts in stages in multiple areas as the temperature increases. The heat transfer suppressing sheet for an assembled battery according to [10], which is applied to the plurality of regions in mutually different application amounts so as to melt.

Further, the above object of the present invention is achieved by the following configuration [13] related to the assembled battery.

[13] An assembled battery in which a plurality of battery cells are connected in series or in parallel, wherein the assembled battery heat transfer suppression sheet according to any one of [1] to [12] is interposed between the battery cells. assembled battery.

The heat transfer suppressing sheet for an assembled battery of the present invention is a heat transfer suppressing sheet used for an assembled battery in which a plurality of battery cells are connected in series or in parallel. Since a portion is formed, a void is formed between the heat insulating material and the covering material, and air exists within this void. Therefore, the air existing inside the gap provides a heat insulating effect, and since the air whose temperature has increased moves within the gap, an excessive rise in temperature can be prevented.
Further, in an abnormal situation where the temperature of the battery cell becomes high, the moisture contained in the heat insulating material evaporates, so that the heat of evaporation can cool the heat insulating material.
Furthermore, in the event of an abnormality in the assembled battery, heated steam is likely to be released to the outside because the recesses and protrusions are formed on the surface of at least one of the heat insulating material and the covering material. Therefore, the propagation of heat between each battery cell can be suppressed.

In the assembled battery of the present invention, since the heat transfer suppressing sheet is interposed between a plurality of battery cells, each battery cell can be cooled during normal use, and in the event of an abnormality, the heat transfer suppressing sheet can be cooled between the battery cells. The propagation of heat can be suppressed, and the chain of thermal runaway can be prevented.

FIG. 1 is a cross-sectional view schematically showing a heat transfer suppressing sheet for an assembled battery according to a first embodiment of the present invention. FIG. 2 is a plan view schematically showing a heat insulating material used in the heat transfer suppressing sheet for an assembled battery according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view schematically showing an assembled battery to which the assembled battery heat transfer suppressing sheet according to the first embodiment of the present invention is applied. FIG. 4 is a cross-sectional view schematically showing a heat transfer suppressing sheet for an assembled battery according to the second embodiment. FIG. 5 is a cross-sectional view schematically showing a heat transfer suppressing sheet for an assembled battery according to the third embodiment. FIG. 6 is a plan view schematically showing another example of the heat insulating material used in the heat transfer suppressing sheet for assembled batteries according to the first to third embodiments. FIG. 7 is a plan view schematically showing still another example of the heat insulating material used in the heat transfer suppressing sheet for assembled batteries according to the first to third embodiments. FIG. 8 is a cross-sectional view schematically showing a heat transfer suppressing sheet for an assembled battery according to the fourth embodiment. FIG. 9 is a plan view schematically showing a heat insulating material used in a heat transfer suppressing sheet for an assembled battery according to the fourth embodiment. FIG. 10 is a cross-sectional view schematically showing the state of the assembled battery heat transfer suppressing sheet according to the fourth embodiment when an abnormality occurs. FIG. 11 is a cross-sectional view schematically showing a heat transfer suppressing sheet for an assembled battery according to the fifth embodiment. FIG. 12 is a cross-sectional view schematically showing a heat transfer suppressing sheet for an assembled battery according to the sixth embodiment. FIG. 13 is a cross-sectional view schematically showing a heat transfer suppressing sheet for an assembled battery according to a seventh embodiment. FIG. 14 is a plan view schematically showing another example of the heat insulating material used in the heat transfer suppressing sheet for assembled batteries according to the fourth to seventh embodiments. FIG. 15 is a plan view schematically showing still another example of the heat insulating material used in the heat transfer suppressing sheet for assembled batteries according to the fourth to seventh embodiments. FIG. 16 is a plan view schematically showing a heat transfer suppressing sheet for an assembled battery using two types of adhesives having different melting temperatures. FIG. 17 is a plan view schematically showing another example of a heat transfer suppressing sheet for an assembled battery using two types of adhesives having mutually different melting temperatures. FIG. 18 is a plan view schematically showing still another example of a heat transfer suppressing sheet for an assembled battery using two types of adhesives having different melting temperatures.

The present inventors have found that it is possible to suppress the propagation of heat between battery cells during abnormal times when high-temperature heat is generated, and to cool each battery cell during normal use when relatively low-temperature heat is generated. We conducted extensive research in order to provide a heat transfer suppression sheet for assembled batteries.

As a result, the present inventors found that when recesses and protrusions are formed on the surface of at least one of the heat insulating material and the covering material, a void is formed between the heat insulating material and the covering material, and within this void. It has been found that the above problem can be solved by the presence of air.

In other words, during normal use when the temperature of the battery cell is relatively low, such as 60°C or less, the air existing inside the void provides a heat insulating effect, and the air with increased temperature moves within the void. Therefore, excessive temperature rise can be prevented.
Further, in an abnormal situation where the temperature of the battery cell becomes high, the moisture contained in the heat insulating material evaporates, so that the heat of evaporation can cool the heat insulating material.

In particular, when the voids communicate with the outside of the heat insulating material and the covering material, air whose temperature has increased during normal use is discharged to the outside, so that the battery cells can be effectively cooled.
Further, in an abnormal situation where the temperature of the battery cells becomes high, heated steam is released to the outside through the gaps, so that it is possible to suppress the propagation of heat between the battery cells.

On the other hand, even if the above-mentioned void does not communicate with the outside of the heat insulating material and the covering material, the void is sealed during normal use, and in the event of an abnormality, there is a connection between the void and the outside of the covering material. If the opening is formed, during normal use, moisture evaporated from the heat insulating material can be retained in the gap, and a heat insulating effect can be obtained.
In addition, in abnormal situations where the temperature of the battery cell becomes high, a communication port is formed that communicates the cavity and the outside of the covering material, and heated steam is released to the outside through the communication port. Propagation of heat between battery cells can be suppressed.

Embodiments of the present invention will be described in detail below with reference to the drawings. Note that the present invention is not limited to the embodiments described below, and can be implemented with arbitrary changes within the scope of the gist of the present invention.
Note that in the following, "~" means greater than or equal to the lower limit value and less than or equal to the upper limit value.

[1. Heat transfer suppression sheet for assembled batteries]
First, heat transfer suppressing sheets for assembled batteries according to the first to seventh embodiments and heat insulating materials applicable to these heat transfer suppressing sheets will be described. Thereafter, the heat insulating material, covering material, etc. that constitute the heat transfer suppressing sheet for assembled batteries will be explained in detail. Furthermore, a method for manufacturing a heat transfer suppressing sheet for an assembled battery according to the present embodiment will be described.
Note that the first to third embodiments described below are examples in which the void portion communicates with the outside of the heat insulating material and the covering material.

<First embodiment>
FIG. 1 is a cross-sectional view schematically showing a heat transfer suppressing sheet for an assembled battery according to a first embodiment. Further, FIG. 2 is a plan view schematically showing a heat insulating material used in the heat transfer suppressing sheet for an assembled battery according to the first embodiment. Note that FIG. 1 is a cross-sectional view taken along the line AA when the heat transfer suppressing sheet 10 is produced using the heat insulating material 11 shown in FIG. Hereinafter, the heat transfer suppressing sheet 10 for an assembled battery may be simply referred to as the heat transfer suppressing sheet 10.
The heat transfer suppression sheet 10 for an assembled battery according to the present embodiment includes a heat insulating material 11 and a covering material 12 that covers the front surface 11a and the back surface 11b, which are the main surfaces of the heat insulating material 11. In this embodiment, the covering material 12 does not cover the end surface 11c of the heat insulating material 11. Note that the front surface 11a and the back surface 11b of the heat insulating material 11 refer to the surface facing the battery cell when the heat transfer suppressing sheet 10 and the battery cell are laminated, and the end surface 11c refers to the surface facing the battery cell when the heat transfer suppressing sheet 10 and the battery cell are laminated, as will be described later. Refers to four surfaces parallel to the thickness direction of the transmission suppression sheet 10.

The heat insulating material 11 contains, for example, inorganic particles and inorganic fibers containing crystal water or adsorbed water, and the crystal water or adsorbed water has a property of releasing moisture when heated. As shown in FIGS. 1 and 2, a plurality of groove-shaped recesses 13a are formed on the surface 11a of the heat insulating material 11 so as to intersect at equal intervals in two directions parallel to the two pairs of sides of the heat insulating material. ing. Moreover, the area where the recess 13a is not formed substantially constitutes the protrusion 13b.

The covering material 12 is, for example, a film, and the convex portion 13b of the heat insulating material 11 and the covering material 12 are bonded with an adhesive (not shown). Note that since the region where the recess 13a is formed does not contact the covering material 12, a gap 14 is formed between the heat insulating material 11 and the covering material 12 as a result. Note that since the recesses 13a are formed to reach the end surfaces 11c of the heat insulating material 11 in four directions, the voids 14 are formed outside the heat insulating material 11 and the covering material 12, that is, the outside of the heat transfer suppressing sheet 10. is connected to.

FIG. 3 is a cross-sectional view schematically showing an assembled battery to which the assembled battery heat transfer suppressing sheet according to the first embodiment is applied. The assembled battery 100 includes a battery case 30, a plurality of battery cells 20 stored inside the battery case 30, and a heat transfer suppression sheet 10 interposed between these battery cells 20. The plurality of battery cells 20 are connected in series or in parallel by bus bars (not shown) or the like.
Note that, for example, a lithium ion secondary battery is preferably used as the battery cell 20, but the present invention is not particularly limited thereto, and may be applied to other secondary batteries.

In the heat transfer suppressing sheet 10 configured in this way, when the temperature rises in a relatively low temperature range from normal temperature (about 20 degrees Celsius) to about 60 degrees Celsius, which is the temperature range of the battery cells 20 during normal use, the heat transfer suppressing sheet 10 becomes insulated. Heat also propagates to the material 11. In this embodiment, the heat insulating material 11 has a cavity 14, and since air exists in the cavity 14, the propagation of heat emitted from the battery cell 20 can be suppressed.
Further, as the temperature rises, the temperature of the air inside the void 14 also rises, but since the void 14 is in communication with the outside of the heat transfer suppressing sheet 10, the warmed air is transferred to the heat transfer suppressing sheet 10. is discharged to the outside. As a result, new air is constantly introduced into the cavity 14, so that it is possible to suppress the rise in temperature of the heat transfer suppressing sheet 10 itself, and also to suppress the rise in the temperature of the battery cells 20. can.

Moreover, when the temperature of the battery cell 20 rises abnormally, even higher heat propagates to the heat insulating material 11 as well. In this embodiment, the heat insulating material 11 contains inorganic particles containing crystal water or adsorbed water, and since the crystal water or adsorbed water is a material that releases water when heated, the heat insulating material 11 is heated. , water evaporates from the inorganic particles. At this time, since the heat insulating material 11 is cooled by removing heat of vaporization, the heat transfer suppressing sheet 10 can cool the battery cells 20.
Note that the high-temperature steam does not stay in the void 14 and is released from the end surface 11c of the heat insulating material 11 to the outside of the heat transfer suppressing sheet 10, so that the heat transfer suppressing sheet 10 can more effectively protect the battery. Cell 20 can be cooled.

Note that when the use (i.e., charging and discharging) of the assembled battery 100 is stopped after the battery cells 20 have been effectively cooled, the water vapor remaining in the cavity 14 is cooled and becomes water droplets, and the It is absorbed into the heat insulating material 11 as time passes. Then, when used next time, the moisture in the heat insulating material 11 evaporates again, and the heat of vaporization is taken away from the heat insulating material 11, allowing the battery cell 20 to be cooled.

<Second embodiment>
FIG. 4 is a cross-sectional view schematically showing a heat transfer suppressing sheet for an assembled battery according to the second embodiment.
In addition, in FIGS. 4 and 5 showing the second and third embodiments below, the same or equivalent parts as in the first embodiment are given the same reference numerals in the drawings, and the description thereof will be omitted or simplified. do. Further, the second and third embodiments shown below can be used in place of the heat transfer suppressing sheet 10 described in the assembled battery 100 shown in FIG. The effects and the like will be explained assuming that the heat transfer suppressing sheet is applied to the assembled battery 100.

The heat transfer suppression sheet 50 for a battery pack according to the second embodiment includes a heat insulating material 51 and a covering material 52 that covers the front surface 51a and the back surface 51b of the heat insulating material 51. Note that, similarly to the first embodiment, the covering material 52 does not cover the end surface 51c of the heat insulating material 51.
In the second embodiment, the front surface 51a and the back surface 51b of the heat insulating material 51 are flat, and no recesses or projections are formed. On the other hand, the covering material 52 is made of a film, and is embossed on the entire surface, and has a recess 53a recessed in the shape of a groove in a direction away from the heat insulating material 51 on the surface facing the heat insulating material 51, and a recessed part 53a facing the heat insulating material 51. A convex portion 53b having a protruding shape is formed. The convex portion 53b of the covering material 52 and the heat insulating material 51 are bonded together with an adhesive (not shown), and a gap 14 is formed between the concave portion 53a and the heat insulating material 51.

Also in the heat transfer suppressing sheet 50 configured in this way, since the voids 14 communicate with the outside of the heat transfer suppressing sheet 50, the same effects as in the first embodiment can be achieved during normal use and in abnormal situations. can be obtained. Note that when constructing the heat transfer suppressing sheet 50 using the covering material 52 shown in the second embodiment, since the covering material 52 made of film is easy to process, it is possible to form the concave portions 53a and convex portions in desired shapes. The portion 53b can be easily created.

<Third embodiment>
FIG. 5 is a cross-sectional view schematically showing a heat transfer suppressing sheet for an assembled battery according to the third embodiment.
A heat transfer suppression sheet 60 for an assembled battery according to the third embodiment includes a heat insulating material 11 and a covering material 52 that covers the front surface 11a and the back surface 11b of the heat insulating material 11. Note that, similarly to the first and second embodiments, the covering material 52 does not cover the end surface 11c of the heat insulating material 11.
In this embodiment, similarly to the first embodiment, the heat insulating material 11 is formed with a recess 13a and a projection 13b. Further, similarly to the second embodiment, the covering material 52 is made of a film whose entire surface is embossed, and grooves are formed on the surface facing the heat insulating material 11 in the direction away from the heat insulating material 11. A concave portion 53a and a convex portion 53b protruding toward the heat insulating material 11 are formed.

In addition, in this embodiment, when the heat insulating material 11 and the covering material 52 are bonded, the position of the groove-shaped recess 53a of the covering material 52 and the position of the groove-like recess 13a of the heat insulating material 11 match, The shape of the covering material 52 is designed so that the position of the convex part 53b of the covering material 52 and the position of the convex part 13b of the heat insulating material 11 match.
The convex portion 53b of the covering material 52 and the convex portion 13b of the heat insulating material 11 are bonded with an adhesive (not shown), and between the concave portion 53a of the sheathing material 52 and the concave portion 13a of the heat insulating material 11, A cavity 14 is formed.

Even in the heat transfer suppressing sheet 60 configured in this way, the same effects as in the first and second embodiments can be obtained during normal use and during abnormal conditions. Furthermore, since the cavity 14 is formed by the recess 13a and the recess 53a, the volume of the cavity 14 is increased compared to the heat transfer suppressing sheets according to the first and second embodiments. Therefore, the temperature of the air in the cavity 14 becomes difficult to rise, and the heat insulation effect of the heat transfer suppressing sheet 60 becomes high. Moreover, since the heated air and high-temperature steam move easily, the effect of cooling the battery cells 20 can be further improved.

Note that in the second and third embodiments, the shapes of the groove-shaped recesses 53a and the convex portions 53b in the covering material 52 are similar to the shape of the surface of the heat insulating material 11 shown in FIG. 5, for example. The present invention is not limited to this. For example, a corrugated covering material having grooves extending only in the direction of a pair of sides of the heat insulating material, or a corrugated covering material having grooves extending in the diagonal direction of the heat insulating material can also be used.

Furthermore, in the first to third embodiments described above, the covering material was placed only on the front and back surfaces of the heat insulating material, but the covering material may cover a part of the cross section or the entire cross section in addition to the front and back surfaces of the heat insulating material. It's okay. However, at least a part of the gap formed between the sheathing material and the heat insulating material may be shaped so that it communicates with the outside of the heat transfer suppressing sheet, or by opening a part of the sheathing material. It is necessary to form a section.

The heat transfer suppressing sheets for assembled batteries according to the first to third embodiments have been described in order above. In addition, in the first to third embodiments described above, an example was given in which the heat insulating material 11 shown in FIG. 2 was used, but the shape of the heat insulating material is not particularly limited. A heat insulating material having the following properties can be used.
Next, other examples of the heat insulating material used in the heat transfer suppressing sheet for assembled batteries according to the first to third embodiments will be shown.

<Other examples of insulation materials>
FIG. 6 is a plan view schematically showing another example of the heat insulating material used in the heat transfer suppressing sheet for assembled batteries according to the first to third embodiments.
As shown in FIG. 6, on the surface 21a of the heat insulating material 21, a plurality of groove-shaped recesses 13a extending in a direction parallel to one side of the heat insulating material 21 are formed at equal intervals. The area where there is no portion substantially constitutes a convex portion 13b. Note that, since the recess 13a is formed to reach the end surface 21c of the heat insulating material 21, when the covering material is adhered to the surface 21a of the heat insulating material 21, the void is formed to the outside of the heat transfer suppressing sheet. communicate.

The heat insulating material 21 configured in this manner can also be applied to the heat transfer suppressing sheets for assembled batteries according to the first to third embodiments, and has the same effects as the first to third embodiments. can be obtained.

<Other examples of insulation materials>
In the insulation material 11 shown in FIG. 2 and the insulation material 21 shown in FIG. 6, all the recesses 13a reach the ends of the insulation material, and all the gaps formed between the insulation material and the covering material Although the portion has a structure that communicates with the outside, the present invention is not limited to this.
FIG. 7 is a plan view schematically showing still another example of the heat insulating material used in the heat transfer suppressing sheet for assembled batteries according to the first to third embodiments.

As shown in FIG. 7, a plurality of groove-shaped recesses 13a extending in one direction are regularly formed on the surface 31a of the heat insulating material 31, and the recesses 13a are formed on a pair of opposing end surfaces 31c of the heat insulating material 31. It has been reached. Moreover, a groove-shaped recess 13c and a groove-shaped recess 13d extending in the same direction as the recess 13a are formed between adjacent recesses 13a. Note that both ends of the recess 13c do not reach the end surface 31c of the heat insulating material 31, and are formed between the recess 13c and the covering material when the covering material is adhered to the surface 31a of the heat insulating material 31. The void portion does not communicate with the outside of the heat transfer suppressing sheet.
Further, in the recessed portion 13d, one end reaches the end face 31c of the heat insulating material 31, and the other end does not reach the end face 31c of the heat insulating material 31. Therefore, when the covering material is adhered to the surface 31a of the heat insulating material 31, the gap formed between the recess 13d and the covering material communicates with the outside of the heat transfer suppressing sheet.

In the heat transfer suppressing sheet using the heat insulating material 31 configured in this way, the voids formed between the recesses 13a and 13d and the covering material communicate with the outside of the heat transfer suppressing sheet. The same effects as in the first to third embodiments described above can be obtained.
Note that the gap formed between the recess 13c and the covering material does not communicate with the outside, so warm air and high-temperature steam are not discharged to the outside and remain in the gap. . However, when charging and discharging of the assembled battery 100 is stopped and the battery cells 20 are cooled, the steam that had accumulated in the voids is also cooled and becomes water droplets, which are absorbed into the heat insulating material 31 over time. Ru. Therefore, the moisture in the heat insulating material 31 can be evaporated again the next time it is used, so that the cooling effect due to the heat of vaporization can be maintained.

Although the first to third embodiments described above are examples in which the void portion communicates with the outside of the heat insulating material and the covering material, the present invention is not limited to such a configuration. For example, if the cavity is sealed during normal use and a communication port is formed that communicates the cavity with the outside of the covering material during abnormal conditions, the The battery cells can be effectively cooled, and heat propagation between each battery cell can be suppressed.

The fourth to seventh embodiments will be described below.
Note that the fourth to seventh embodiments shown below can also be used in place of the heat transfer suppressing sheet 10 described in the assembled battery 100 shown in FIG. The effects and the like will be explained assuming that such a heat transfer suppressing sheet is applied to the assembled battery 100.

<Fourth embodiment>
FIG. 8 is a cross-sectional view schematically showing a heat transfer suppressing sheet for an assembled battery according to the fourth embodiment. Further, FIG. 9 is a plan view schematically showing a heat insulating material used in a heat transfer suppressing sheet for an assembled battery according to the fourth embodiment. The fourth embodiment shown in FIGS. 8 and 9 differs from the first embodiment shown in FIGS. 1 and 2 only in the shape of the recess 13a and the presence or absence of communication with the outside. Therefore, in FIGS. 8 and 9, the same or equivalent parts as in the first embodiment will be denoted by the same reference numerals in the drawings, and the description thereof will be omitted or simplified.

As shown in FIGS. 8 and 9, a plurality of recesses 13a are regularly formed on the surface 71a of the heat insulating material 71 constituting the heat transfer suppressing sheet 70, and areas where no recesses 13a are formed are This substantially constitutes a convex portion 13b.
The recesses 13a are, for example, rectangular in plan view, and as shown in FIG. are arranged alternately.

Further, the covering material 12 is, for example, a polymer film that melts at a temperature of 60° C. or higher, and the convex portion 13b of the heat insulating material 71 and the covering material 12 are bonded with an adhesive (not shown). In this embodiment, an adhesive made of an organic substance or an inorganic substance is used, and this adhesive has a property of melting at 60° C. or higher.
Note that since the region where the recess 13a is formed does not contact the covering material 12, a gap 14 is formed between the heat insulating material 71 and the covering material 12 as a result. Since the convex portion 13b located around the cavity 14 and the covering material 12 are bonded together, the cavity 14 is always in a sealed state at a temperature below 60°C.

In the heat transfer suppressing sheet 70 configured in this way, when the temperature rises in a relatively low temperature range from normal temperature (about 20 degrees Celsius) to about 150 degrees Celsius, which is the temperature range of the battery cells 20 during normal use, the heat transfer suppressing sheet 70 becomes insulated. Heat also propagates to the material 71. In this embodiment, the heat insulating material 71 contains inorganic particles containing crystal water or adsorbed water, and since the crystal water or adsorbed water is a material that releases moisture when heated, the insulating material 71 is not heated. As a result, water evaporates from the inorganic particles. A part of the evaporated water stays in the cavity 14, and the other part is released from the end surface 71c side of the heat insulating material 71. At this time, since the heat insulating material 71 is cooled by removing the heat of vaporization, the heat transfer suppressing sheet 70 can effectively cool the battery cells 20.

Note that when the use (i.e., charging and discharging) of the assembled battery 100 is stopped after the battery cells 20 have been effectively cooled, the water vapor that has accumulated in the voids 14 is cooled and becomes water droplets, and the water vapor accumulates over time. It is absorbed into the heat insulating material 71 as time passes. Then, when used next time, the moisture in the heat insulating material 71 evaporates again, and the heat insulating material 71 is deprived of the heat of vaporization, thereby repeating the cycle of cooling the battery cells 20.

FIG. 10 is a cross-sectional view schematically showing the state of the assembled battery heat transfer suppressing sheet according to the fourth embodiment when an abnormality occurs. Note that the front surface 71a of the heat insulating material 71 shows a state in which a part of the covering material 12 is melted, and the back surface 71b shows a state in which the adhesive bonding the covering material 12 and the heat insulating material 71 has melted due to a rise in temperature. represents.
As shown in FIG. 10, when an abnormality occurs, for example, when the temperature of the battery cell 20 rises to, for example, 200° C. or higher, the covering material 12 melts and a communication port 15 is formed that communicates the cavity 14 with the outside. . Furthermore, even when the coating material 12 that does not melt even at high temperatures is used, when the adhesive melts, a communication port 15 is formed that communicates the gap 14 with the outside of the heat transfer suppressing sheet 70.

When the communication ports 15 are formed in this way, the steam that evaporates from the inorganic particles and stays in the voids 14 and reaches a high temperature is released to the outside of the heat transfer suppressing sheet 70 through the communication ports 15. . Therefore, even if the battery cells 20 cause thermal runaway, the propagation of heat between the battery cells 20 can be effectively suppressed.

The polymer film and adhesive used in this embodiment both have the property of melting at any temperature of 60° C. or higher. That is, in a temperature range of less than 60° C., the void portion 14 is always in a sealed state. Since polymer films and adhesives have various melting temperatures depending on their type, a polymer film or adhesive having a desired melting temperature in the range of 60° C. or higher can be selected as necessary.
Note that the temperature at which the communication port that communicates the void portion 14 with the outside of the covering material 12 is formed is preferably 80° C. or higher, and more preferably 100° C. or higher.
On the other hand, the upper limit of the temperature at which the communication port connecting the void 14 and the outside of the covering material 12 is formed, that is, the upper limit of the temperature at which the polymer film or adhesive melts, is not particularly specified, but is 500°C or less. The temperature is preferably 350°C or lower, more preferably 300°C or lower, and particularly preferably 250°C or lower.

<Fifth embodiment>
FIG. 11 is a cross-sectional view schematically showing a heat transfer suppressing sheet for an assembled battery according to the fifth embodiment.
In FIG. 11 showing the fifth embodiment below, the same or equivalent parts as in the fourth embodiment are given the same reference numerals in the drawings, and the explanation thereof will be omitted or simplified.

A heat transfer suppressing sheet 80 for an assembled battery according to the fifth embodiment includes a heat insulating material 71 and a covering material 12 that covers a front surface 71a, a back surface 71b, and an end surface 71c, which are the main surfaces of the heat insulating material 71. In this embodiment, the end face 71c of the heat insulating material 71 is also formed with a recess 13a and a protrusion 13b. That is, the covering material 12 formed into a bag shape using an adhesive (not shown) or the like covers the entire surface of the heat insulating material 71, and the heat insulating material 71 is completely sealed by the covering material 12.

Also in the heat transfer suppressing sheet 80 configured in this way, the same effects as in the fourth embodiment can be obtained during normal use. In the fifth embodiment, since the insulation material 71 is completely covered with the coating material 12, when the insulation material 71 is heated during normal use and water evaporates from the inorganic particles, all of the evaporated water is removed. Moisture remains in the voids 14 and is not released from the heat transfer suppressing sheet 80 to the outside. However, since the moisture evaporates, the heat insulating material 71 is cooled by being deprived of the heat of vaporization, and the heat transfer suppressing sheet 80 can effectively cool the battery cells 20.

Furthermore, in the fifth embodiment, since the evaporated water is not released to the outside, most of the evaporated water is absorbed into the heat insulating material 71 again when the assembled battery is stopped from being used. Therefore, according to the assembled battery heat transfer suppression sheet 80 according to the fifth embodiment, the effect of cooling the battery cells 20 can be maintained for a long period of time.

Furthermore, in an abnormal situation, the adhesive bonding the covering materials 12 to each other may melt, or the covering material 12 may melt, resulting in a gap between the gap 14 and the outside, as in the case shown in FIG. Since the communication port is formed, the same effects as in the fourth embodiment can be obtained.

<Sixth embodiment>
FIG. 12 is a cross-sectional view schematically showing a heat transfer suppressing sheet for an assembled battery according to the sixth embodiment. Note that in FIG. 12 showing the sixth embodiment below, the same or equivalent parts as in the second embodiment shown in FIG.

In the battery pack heat transfer suppression sheet 90 according to the sixth embodiment, the surface of the heat insulating material 51 is flat, and no concave portions or convex portions are formed. On the other hand, the covering material 52 is made of a film, has an embossed surface, and has a concave portion 53a recessed in a direction away from the heat insulating material 51 on the surface facing the heat insulating material 51, and a concave portion 53a protruding from the heat insulating material 51. A convex portion 53b is formed. The convex portion 53b of the covering material 52 and the heat insulating material 51 are bonded with an adhesive (not shown), and a sealed gap 14 is formed between the concave portion 53a and the heat insulating material 51. .

Even in the heat transfer suppressing sheet 90 configured in this way, the same effects as in the fourth embodiment can be obtained during normal use and during abnormal conditions. Note that by configuring the heat transfer suppressing sheet to cover the entire surface of the heat insulating material 51 using the covering material 52 shown in the sixth embodiment, the battery cell 20 can be protected as in the fifth embodiment. The cooling effect can be maintained for a long period of time.

<Seventh embodiment>
FIG. 13 is a cross-sectional view schematically showing a heat transfer suppressing sheet for an assembled battery according to a seventh embodiment. In FIG. 13 showing the seventh embodiment below, the same or equivalent parts as in the third embodiment shown in FIG.
A heat transfer suppression sheet 95 for an assembled battery according to the seventh embodiment includes a heat insulating material 71 and a covering material 52 that covers the entire surface of the heat insulating material 71. In this embodiment, the heat insulating material 71 has a concave portion 13a and a convex portion 13b formed therein. The covering material also has a recess 53a recessed in a direction away from the heat insulating material 71 and a convex portion 53b projecting toward the insulating material 71 on the surface facing the heat insulating material 71. The convex portion 53b of the covering material 52 and the convex portion 13b of the heat insulating material 71 are bonded with an adhesive (not shown), and between the concave portion 53a of the sheathing material 52 and the concave portion 13a of the heat insulating material 71, A sealed cavity 14 is formed.

In the heat transfer suppressing sheet 95 configured in this way, the same effects as in the fourth embodiment can be obtained during normal use and during abnormal conditions. Furthermore, since the cavity 14 is formed by the recess 13a and the recess 53a, the volume of the cavity 14 is increased compared to the heat transfer suppressing sheets for assembled batteries according to the fourth to sixth embodiments. Therefore, moisture easily evaporates from the heat insulating material 71, and the effect of cooling the battery cells 20 during normal use can be further improved.

In the seventh embodiment, the covering material 52 is configured to cover the end face 71c of the heat insulating material 71, but the end face 71c of the heat insulating material 71 may be left open, as in the fourth embodiment. By opening the end face 71c, some of the evaporated water is released to the outside during normal use, so the water in the heat insulating material 71 evaporates more easily, and the cooling effect due to the heat of vaporization can be enhanced. .
In addition, even if the coating material 52 that does not melt at high temperatures is used in an abnormal situation, when the adhesive melts, the communication port 15 that communicates the gap 14 with the outside of the heat transfer suppressing sheet 95 is formed. Therefore, the effect of cooling the battery cells 20 can be obtained.

The heat transfer suppressing sheets for assembled batteries according to the fourth to seventh embodiments have been described above in order. Next, other examples of the heat insulating material used in the heat transfer suppressing sheets for assembled batteries according to the fourth to seventh embodiments will be shown.

<Other examples of insulation materials>
FIG. 14 is a plan view schematically showing another example of the heat insulating material used in the heat transfer suppressing sheet for assembled batteries according to the fourth to seventh embodiments. In addition, in the said 4th, 5th, and 7th embodiment, although the example which used the heat insulating material 71 shown in FIG. 9 was given, the shape of a heat insulating material is not specifically limited.
As shown in FIG. 14, a plurality of recesses 13a are regularly formed on the surface 41a of the heat insulating material 41, and areas where no recesses 13a are formed substantially constitute protrusions 13b. .
In this embodiment, the recesses 13a are, for example, rectangular in plan view, and all the recesses 13a are arranged so that the longitudinal direction thereof is parallel to one side of the heat insulating material 41.
The heat insulating material 41 configured in this manner can also be applied to the heat transfer suppressing sheets for assembled batteries according to the fourth to seventh embodiments, and has the same effects as the fourth to seventh embodiments. can be obtained.

<Other examples of insulation materials>
FIG. 15 is a plan view schematically showing still another example of the heat insulating material used in the heat transfer suppressing sheet for assembled batteries according to the fourth to seventh embodiments.
Although the heat insulating material 71 shown in FIG. 9 and the heat insulating material 41 shown in FIG. 14 have a structure in which all the recesses 13a are sealed with a covering material, the present invention is not limited to this.
As shown in FIG. 15, a plurality of recesses 13a are regularly formed on the surface 61a of the heat insulating material 61, and areas where no recesses 13a are formed substantially constitute protrusions 13b. . However, the recess 13c formed near the end surface 61c of the heat insulating material 61 reaches the end surface 61c of the heat insulating material 61.

For example, when the heat insulating material 71 in the fourth embodiment is replaced with the above heat insulating material 61, the recess 13c formed near the end surface 61c of the heat insulating material 61 does not constitute a sealed void. However, since a sealed gap is formed between some of the recesses 13a and the covering material 12, the same effects as in the fourth to seventh embodiments can be obtained.

Next, the heat insulating material, coating material, adhesive, and thickness of the heat transfer suppressing sheet that constitute the heat transfer suppressing sheet for an assembled battery according to the present embodiment will be described in detail.

<Insulation material>
The heat insulating material used in the heat transfer suppressing sheet for assembled batteries according to this embodiment contains at least one of inorganic particles and inorganic fibers.
The inorganic particles are preferably inorganic hydrates or water-containing porous bodies. The inorganic hydrate receives heat from the battery cell 20, and when the temperature reaches or exceeds the thermal decomposition start temperature, it thermally decomposes and cools the battery cell 20 by releasing its crystal water. Furthermore, after releasing the crystal water, it becomes a porous body, and the countless air holes provide an effective heat insulating effect.
Further, as the inorganic particles, a single inorganic particle may be used, or two or more types of inorganic hydrate particles may be used in combination. Since the thermal decomposition start temperature of inorganic hydrates differs depending on the type, the battery cell 20 can be cooled in multiple stages by using two or more types of inorganic hydrate particles together.

Specific examples of inorganic hydrates include aluminum hydroxide (Al(OH) ₃ ), magnesium hydroxide (Mg(OH) ₂ ), calcium hydroxide (Ca(OH) ₂ ), and zinc hydroxide (Zn(OH) 2 ). ) ₂ ), iron hydroxide (Fe(OH) ₂ ), manganese hydroxide (Mn(OH) ₂ ), zirconium hydroxide (Zr(OH) ₂ ), gallium hydroxide (Ga(OH) ₃ ), etc. It will be done.
Furthermore, examples of the fibrous inorganic hydrate include fibrous calcium silicate hydrate.

Specific examples of the water-containing porous material include zeolite, kaolinite, montmorillonite, acid clay, diatomaceous earth, sepiolite, wet silica, dry silica, aerogel, mica, and vermiculite.

Furthermore, examples of inorganic fibers include alumina fibers, silica fibers, alumina silicate fibers, rock wool, magnesium silicate fibers, alkali earth silicate fibers, glass fibers, zirconia fibers, and potassium titanate fibers. Among these inorganic fibers, magnesium silicate fibers can be suitably used as a material that releases moisture upon heating.
In addition, regarding the inorganic fibers, a single inorganic fiber may be used, or two or more types of inorganic fibers may be used in combination.

In addition to the above-mentioned inorganic particles and inorganic fibers, the heat insulating material may contain organic fibers, organic binders, and the like, if necessary. All of these are useful for reinforcing heat insulating materials and improving formability.

Note that the inorganic particles and inorganic fibers contained in the heat insulating material do not necessarily need to contain a material that releases moisture upon heating. When the insulation material is manufactured, it inevitably contains a small amount of moisture, so when the temperature of the battery cell 20 rises during normal use or during abnormal conditions, the moisture contained in the insulation material evaporates, causing the battery cell to deteriorate. It is possible to obtain the effect of cooling 20.

In this embodiment, the heat insulating material may contain at least one of inorganic particles and inorganic fibers, but the content of inorganic particles is 20% by mass or more and 80% by mass or less with respect to the total mass of the heat transfer suppressing sheet. The content of inorganic fibers is preferably 5% by mass or more and 70% by mass or less. With such a content, the inorganic fibers can improve shape retention, resistance to pressing force, and resistance to wind pressure, and can ensure the ability to retain inorganic particles.

The heat transfer suppressing sheet according to this embodiment may contain organic fibers, an organic binder, and the like, if necessary. All of these are useful for reinforcing the heat transfer suppressing sheet and improving formability.

<Coating material>
As the covering material, a polymer film or a metal film (metal plate) can be used.
Polymer films include polyimide, polycarbonate, PET, p-phenylene sulfide, polyetherimide, crosslinked polyethylene, flame-retardant chloroprene rubber, polyvinyldenfluoride, hard vinyl chloride, polybutylene terephthalate, PTFE, PFA, FEP, ETFE, Examples include rigid PCV, flame-retardant PET, polystyrene, polyethersulfone, polyamideimide, polyacrylonitrile, polyethylene, polypropylene, polyamide, and the like.

The melting point of the polymer film is 60°C to 600°C. It is preferable that the polymer film melts at a temperature of 60°C or higher because the coating material (polymer film) can seal the void at a temperature of less than 60°C. Further, it is preferable that the polymer film is melted at an arbitrary temperature of 60° C. or higher because a communication port is formed that communicates the void with the outside of the coating material.
In this embodiment, when a polymer film is used as the coating material, the melting temperature of the polymer film is preferably 60°C or higher, more preferably 80°C or higher, and 100°C or higher. It is even more preferable.
On the other hand, the melting temperature of the polymer film is preferably 500°C or lower, more preferably 350°C or lower, even more preferably 300°C or lower, and particularly preferably 250°C or lower.

Further, examples of the metal film include aluminum foil, stainless steel foil, copper foil, and the like.

<Adhesive>
In this embodiment, as a method of sealing the gap formed between the heat insulating material and the covering material, it is possible to apply a method of bonding the heat insulating material and the covering material or a method of bonding the covering materials to each other. can.
Examples of the adhesive for bonding the heat insulating material and the covering material include those made from urethane, polyethylene, polypropylene, polystyrene, nylon, polyester, vinyl chloride, vinylon, acrylic resin, silicone, and the like.
In addition, the said adhesive can also be applied as an adhesive which adhere|attaches covering materials.

It is preferable that the adhesive melts at a temperature of 60°C or higher, since the coating material can seal the void at a temperature of less than 60°C. Further, it is preferable that the adhesive is melted at an arbitrary temperature of 60° C. or higher because a communication port is formed that communicates the gap with the outside of the covering material.
In this embodiment, when an adhesive is used, the melting temperature of the adhesive is preferably 60°C or higher, more preferably 80°C or higher, and even more preferably 100°C or higher.
On the other hand, the melting temperature of the adhesive is preferably 500°C or lower, more preferably 350°C or lower, even more preferably 300°C or lower, and particularly preferably 250°C or lower.

Further, as a method of sealing the gap formed between the heat insulating material and the covering material, a method of covering the entire heat insulating material with the covering material can also be applied.
Examples of methods for covering the entire heat insulating material with a covering material include lamination (dry laminate, thermal laminate), pouch laminate, vacuum pack, vacuum lamination, shrink packaging, caramel packaging, and the like.

It should be noted that multiple adhesives with different melting temperatures may be used to bond the insulation material and the covering material, or between the covering materials, so that they melt in stages in multiple areas as the temperature increases. good. An example of using multiple adhesives will be described below with reference to the drawings. Note that the examples shown in FIGS. 16 to 18 below are modified examples of the heat transfer suppression sheet 70 for an assembled battery according to the fourth embodiment shown in FIGS. 8 and 9.

FIG. 16 is a plan view schematically showing a heat transfer suppressing sheet for an assembled battery using two types of adhesives having different melting temperatures.
As shown in FIG. 16, in the heat transfer suppressing sheet 110 for assembled batteries, adhesive 16b is used on the peripheral edge near the end face of the area of the convex part 13b of the heat insulating material 71, and the area inside this area is Adhesive 16a is used. The adhesive 16a and the adhesive 16b have different melting temperatures, and specifically, the adhesive 16b is designed to have a higher melting temperature than the adhesive 16a. Further, the melting temperature of the covering material is designed to be higher than the melting temperature of the adhesive 16b.

In the heat transfer suppressing sheet 110 configured in this manner, as a first step, the gaps between each recess 13a and the covering material are sealed at a temperature lower than the melting temperature of the adhesive 16a. Therefore, when the heat insulating material 71 is heated and water evaporates from the inorganic particles, all of the evaporated water stays in the voids and is not released from the heat transfer suppression sheet 110 to the outside. The material 71 is cooled by removing heat of vaporization.

After that, in the second stage, when the temperature of the battery cell further increases and becomes higher than the melting temperature of the adhesive 16a and lower than the melting temperature of the adhesive 16b, the area bonded by the adhesive 16a is separated, and the gap is Since the volume increases, moisture easily evaporates from the heat insulating material 71. In addition, the heated steam does not stay in a fixed position and can move over a wider area than in the first stage, so the heat transfer suppressing sheet 110 can effectively cool the battery cells.

Furthermore, as a third step, when the temperature of the battery cell becomes equal to or higher than the melting temperature of the adhesive 16b, the area bonded by the adhesive 16b is separated, and the gap is communicated with the outside of the heat transfer suppressing sheet 110. A communication port is formed. As a result, the high-temperature steam that has been staying inside the area of the adhesive 16b is released at once. Therefore, even when a battery cell causes thermal runaway, the propagation of heat between battery cells can be effectively suppressed.

FIG. 17 is a plan view schematically showing another example of a heat transfer suppressing sheet for an assembled battery using two types of adhesives having mutually different melting temperatures.
As shown in FIG. 17, in the heat transfer suppression sheet 120, similar to the heat transfer suppression sheet 110 shown in FIG. Agent 16b is used. However, the adhesive 16a, which is the same as the inner region and has a lower melting temperature, is used only in a portion of the peripheral edge.

In the heat transfer suppressing sheet 120 configured in this way, as a first step, the gaps between the recesses 13a and the covering material are sealed at a temperature lower than the melting temperature of the adhesive 16a. Therefore, similarly to the heat transfer suppressing sheet 110 shown in FIG. 16, moisture evaporates from the heat insulating material 71 toward the void, and the heat insulating material 71 is cooled by being deprived of the heat of vaporization.

After that, in the second stage, when the temperature of the battery cell further rises and exceeds the melting temperature of the adhesive 16a, the area bonded by the adhesive 16a is separated, and moisture easily evaporates from the heat insulating material 71. Become. Further, since the adhesive 16a having a low melting temperature is used only in a portion of the peripheral edge, this region serves as a communication port that communicates the gap with the outside of the heat transfer suppressing sheet 110. Therefore, as shown by arrows in FIG. 17, high-temperature steam is released from the communication ports, so that the propagation of heat between battery cells can be effectively suppressed.

As shown in FIG. 17, if the adhesive 16a, which has the same lower melting temperature as the inner area, is used only in a portion of the periphery, it will be easier to locate the location where high-temperature steam (moisture) is released. can be controlled. Therefore, it is possible to suppress water exposure to predetermined components within the assembled battery.

FIG. 18 is a plan view schematically showing still another example of a heat transfer suppressing sheet for an assembled battery using two types of adhesives having different melting temperatures.
As shown in FIG. 18, in the heat transfer suppression sheet 130, similar to the heat transfer suppression sheet 120 shown in FIG. 16b is used. However, the adhesive 16a having a low melting temperature is used only in a portion of the peripheral edge, and this area becomes a communication port when the temperature is high. Further, an adhesive 16c having the same melting temperature as the adhesive 16b is used in an area spaced apart from the peripheral edge at a predetermined distance inside the area where the adhesive 16b is used. Note that also in the area where the adhesive 16c is used, the adhesive 16a having a partially low melting temperature is used on the opposite side of the area serving as the communication port.

In the heat transfer suppressing sheet 130 configured in this way, the first stage is the moisture evaporating from the heat insulating material 71 toward the void, and the heat insulating material 71 is vaporized, similar to the heat transfer suppressing sheet 120 shown in FIG. Heat is removed and the body is cooled.
Thereafter, in the second step, when the adhesive 16a is melted, a moisture release path is formed as shown by the arrow in FIG. As a result, the high-temperature steam moves along the release path and is released to the outside through the communication port, thereby making it possible to further improve the cooling effect.
Note that the adhesive 16a, the adhesive 16b, and the adhesive 16c may all have different melting temperatures, and the area in which each adhesive is used can also be arbitrarily determined depending on the purpose.

As described above, the heat transfer suppressing sheets 110, 120, and 130 shown in FIGS. 16 to 18 are designed so that the adhesive gradually melts in multiple regions as the temperature of the battery cell increases.
Therefore, it is possible to adjust the timing at which the steam accumulated in the gap is released, to provide a steam release port at an arbitrary position, and to provide an arbitrary release path.

In order to obtain the above effect, it is sufficient to design the adhesive so that it melts in stages in multiple areas as the temperature rises. Alternatively, a method such as applying adhesive in different amounts to multiple areas can be used.
In addition, in FIGS. 16 to 18, in a heat transfer suppression sheet in which a covering material is adhered to the front and back sides of the heat insulating material 71, the adhesive bonding the heat insulating material 71 and the covering material melts in stages. Although the case has been described, the present invention is not limited to such a case. For example, even in a configuration in which the heat insulating material 71 is completely covered with a covering material, a method of adjusting the melting temperature or application amount of the adhesive depending on the region can be applied. Specifically, when the covering materials are bonded to each other near the end face of the heat insulating material 71, the melting temperature of the adhesive that bonds the covering materials to each other is set high, and the heat insulating material 71 and the covering material are bonded together. By setting the melting temperature of the adhesive to be low, the same effect as that of the heat transfer suppressing sheet 110 can be obtained.

<Thickness of heat transfer suppression sheet>
In this embodiment, the thickness of the heat transfer suppressing sheet is not particularly limited, but is preferably in the range of 0.05 to 6 mm. If the thickness of the heat transfer suppressing sheet is less than 0.05 mm, sufficient mechanical strength cannot be imparted to the heat transfer suppressing sheet. On the other hand, if the thickness of the heat transfer suppressing sheet exceeds 6 mm, it may be difficult to form the heat transfer suppressing sheet itself.

Next, a method for manufacturing a heat transfer suppressing sheet for an assembled battery according to the present embodiment will be described.

<Method for manufacturing heat transfer suppression sheet>
The heat insulating material used in the heat transfer suppressing sheet according to the present embodiment can be manufactured by, for example, molding a material containing at least one of inorganic particles and inorganic fibers using a dry molding method or a wet molding method. As for the dry molding method, for example, a press molding method (dry press molding method) and an extrusion molding method (dry extrusion molding method) can be used.

(Method for producing heat insulating material using dry press molding method)
In the dry press molding method, inorganic particles and inorganic fibers, and if necessary, organic fibers, organic binder, etc. are charged into a mixer such as a V-type mixer at a predetermined ratio. Then, after thoroughly mixing the materials put into the mixer, the mixture is put into a predetermined mold and press-molded to obtain a heat insulating material. During press molding, heating may be performed if necessary.
The heat insulating material having concave portions and convex portions can be formed, for example, by a method of pressing using a mold having concave and convex portions during press molding.

Note that the press pressure during press molding is preferably in the range of 0.98 MPa or more and 9.80 MPa or less. If the press pressure is less than 0.98 MPa, the resulting heat insulating material may not have sufficient strength and may collapse. On the other hand, if the press pressure exceeds 9.80 MPa, there is a risk that workability may be reduced due to excessive compression, or that solid heat transfer may increase due to increased bulk density, resulting in a reduction in heat insulation properties.

Furthermore, when using the dry press molding method, it is preferable to use ethylene-vinylacetate copolymer (EVA) as the organic binder; Any organic binder can be used without particular limitation.

(Method for producing heat insulating material using dry extrusion method)
In the dry extrusion molding method, a paste is prepared by adding water to inorganic particles, inorganic fibers, and, if necessary, organic fibers and an organic binder as binders, and kneading them with a kneader. Thereafter, a heat insulating material can be obtained by extruding the obtained paste through a slit-shaped nozzle using an extrusion molding machine and drying it. When using the dry extrusion method, it is preferable to use methyl cellulose, water-soluble cellulose ether, etc. as the organic binder, but if it is an organic binder commonly used when using the dry extrusion method, there are no particular limitations. It can be used without.
Note that, for example, as a method for producing the heat insulating material 21 having concave portions and convex portions as shown in FIG. Here are some ways to push it out.
Further, for example, the recesses 13a in the heat insulating material shown in FIGS. 2, 7, 9, and 14 are formed by extruding the paste, which is the raw material, from a slit-shaped nozzle, and forming the sheet obtained by this before drying. It can be formed by a method such as cutting the surface to form a desired recess.

(Method for producing heat insulating material using wet molding method)
In the wet molding method, a mixed liquid is prepared by mixing inorganic particles, inorganic fibers, and, if necessary, an organic binder as a binding material in water and stirring with a stirrer. Thereafter, the obtained liquid mixture is poured into a molding machine having a mesh for filtration formed on the bottom surface, and the liquid mixture is dehydrated through the mesh, thereby producing a wet sheet. Thereafter, a heat insulating material can be obtained by heating and pressurizing the obtained wet sheet.
Note that before the heating and pressurizing process, an aeration drying process may be performed in which hot air is aerated through the wet sheet to dry the sheet, but this aeration drying process is not performed and the sheet is heated and Pressure may be applied.
Further, when using a wet molding method, an acrylic emulsion using polyvinyl alcohol (PVA) can be selected as the organic binder.
An example of a method for manufacturing a heat insulating material having concave and convex portions by a wet molding method is a method in which a wet sheet is press-molded using a mold having concavities and convexities before heating and pressurizing. can.

(Method for manufacturing coating material)
As the covering material, the above-mentioned general-purpose polymer film manufactured to a desired thickness or a metal film can be used, and the unevenness can be formed on the film by press-molding using a mold with unevenness. can be formed.

(Method for manufacturing heat transfer suppressing sheet)
The heat transfer suppressing sheet according to the present embodiment can be manufactured, for example, by applying an adhesive to the heat insulating material or covering material obtained as described above and bonding the heat insulating material and the covering material. .
In addition, as a method of covering the entire insulation material with a covering material, for example, the insulation material is sandwiched between two pieces of covering material that are cut larger than the surface of the insulation material, and the covering materials are wrapped around each other around the insulation material. Examples include methods of bonding by thermocompression bonding or adhesive.

[2. Assembled battery]
The assembled battery according to this embodiment is an assembled battery in which a plurality of battery cells are connected in series or in parallel, and the assembled battery heat transfer suppression sheet according to this embodiment is interposed between the battery cells. be. Specifically, as shown in FIG. 3, for example, the assembled battery 100 includes a plurality of battery cells 20 arranged in parallel, connected in series or parallel, and housed in a battery case 30. A heat transfer suppressing sheet 10 is interposed between them.

In such an assembled battery 100, since the heat transfer suppressing sheet 10 is interposed between each battery cell 20, each battery cell 20 can be cooled during normal use.
Further, even if one battery cell among the plurality of battery cells 20 experiences thermal runaway and reaches a high temperature, expands or ignites, the presence of the heat transfer suppressing sheet 10 according to the present embodiment prevents the battery Propagation of heat between cells 20 can be suppressed. Therefore, a chain of thermal runaway can be prevented, and the adverse effects on the battery cells 20 can be minimized.

10, 50, 60, 70, 80, 90, 95, 110, 120, 130 Heat transfer suppression sheet for assembled battery 11, 21, 31, 41, 51, 61, 71 Heat insulating material 12, 52 Covering material 13a, 13c, 53a Concave portions 13b, 53b Convex portion 14 Gap portion 15 Communication port 20 Battery cell 30 Battery case 100 Assembled battery

Claims (11)

A heat transfer suppression sheet for an assembled battery, which is used for an assembled battery in which a plurality of battery cells are connected in series or parallel, and is interposed between the battery cells,
A heat insulating material containing at least one of inorganic particles and inorganic fibers;
a covering material that covers at least a portion of the heat insulating material;
The heat insulating material has a concave portion and a convex portion on a surface facing the coating material,
A gap is formed between the recess and the covering material ,
A heat transfer suppressing sheet for an assembled battery, wherein the convex portion of the heat insulating material and the covering material are bonded to each other . A heat transfer suppression sheet for an assembled battery, which is used for an assembled battery in which a plurality of battery cells are connected in series or parallel, and is interposed between the battery cells,
A heat insulating material containing at least one of inorganic particles and inorganic fibers;
a covering material that covers at least a portion of the heat insulating material;
The covering material has a concave part and a convex part on a surface facing the heat insulating material,
A heat transfer suppressing sheet for an assembled battery, wherein a gap is formed between the recess and the heat insulating material . The heat transfer suppression sheet for an assembled battery according to claim 2 , wherein the convex portion of the covering material and the heat insulating material are bonded to each other. A heat transfer suppression sheet for an assembled battery, which is used for an assembled battery in which a plurality of battery cells are connected in series or parallel, and is interposed between the battery cells,
A heat insulating material containing at least one of inorganic particles and inorganic fibers;
a covering material that covers at least a portion of the heat insulating material;
The heat insulating material has a concave portion and a convex portion on a surface facing the coating material,
The covering material has a concave part and a convex part on a surface facing the heat insulating material,
A heat transfer suppressing sheet for an assembled battery, wherein a gap is formed between the recess of the heat insulating material and the recess of the coating material . The heat transfer suppression sheet for an assembled battery according to claim 4 , wherein the convex portion of the heat insulating material and the convex portion of the coating material are bonded to each other. The heat transfer suppressing sheet for an assembled battery according to any one of claims 2 to 4 , wherein the covering material is composed of an embossed polymer film or a metal plate. The heat transfer suppressing sheet for an assembled battery according to any one of claims 1 to 6 , wherein the void portion communicates with the outside of the heat insulating material and the covering material. A heat transfer suppression sheet for an assembled battery, which is used for an assembled battery in which a plurality of battery cells are connected in series or parallel, and is interposed between the battery cells,
A heat insulating material containing at least one of inorganic particles and inorganic fibers;
a covering material that covers at least a portion of the heat insulating material;
having a concave portion and a convex portion on at least one of the surface of the heat insulating material facing the covering material and the surface of the covering material facing the heat insulating material;
A void is formed between the heat insulating material and the covering material ,
The void is sealed at a temperature of less than 60°C,
A heat transfer suppressing sheet for an assembled battery, wherein the covering material is configured to form a communication port that communicates the void portion with the outside of the covering material at a temperature of 60° C. or higher . The heat insulating material and the coating material, or the coating materials are bonded together with an adhesive that melts at a temperature of 60° C. or higher, and the adhesive melts in stages in multiple regions as the temperature rises. The heat transfer suppressing sheet for an assembled battery according to claim 8 , wherein a plurality of adhesives having mutually different melting temperatures are used in the plurality of regions. The heat insulating material and the covering material, or the covering materials are bonded together with an adhesive that melts at a temperature of 60° C. or higher, and the adhesive melts in stages in multiple regions as the temperature rises. The heat transfer suppressing sheet for an assembled battery according to claim 8 , wherein the heat transfer suppressing sheet for an assembled battery is applied to the plurality of regions in different amounts. An assembled battery in which a plurality of battery cells are connected in series or in parallel, wherein the assembled battery heat transfer suppressing sheet according to any one of claims 1 to 10 is interposed between the battery cells. .

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