JP2013178909A - Secondary battery, battery pack using the same, and sheet-like thermal storage member for secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery in which thermorunaway is prevented by suppressing rapid battery temperature rise upon occurrence of abnormal heating in the battery due to overcharge or overdischarge, and fire can be extinguished or prevented from spreading even if thermorunaway causes fire.SOLUTION: The secondary battery includes a battery body constituted by housing a positive electrode and a negative electrode in a battery container, and a latent heat storage material attached to the battery body and consisting of inorganic acetate or inorganic hydrogen carbonate generating COgas by thermolysis, e.g., a heat storage member containing sodium acetate. Rapid battery temperature rise of the battery body is suppressed by latent heat storage, and even if it causes fire, fire is extinguished and prevented from spreading by generation of COgas incident to decomposition of the latent heat storage material, and endothermic reaction of decomposition.

Description

  The present invention, as a secondary battery represented by a lithium ion battery used in an electric vehicle or the like, a secondary battery to which a function for preventing danger when abnormal heat is generated due to overcharge or overdischarge, and The present invention relates to an assembled battery in which a large number of the batteries are incorporated, and a sheet-like heat storage member used therefor.

  As is well known, in a secondary battery such as a lithium ion battery, when the battery is overcharged or overdischarged, the battery deteriorates and abnormal heat may be generated at the same time. On the other hand, in applications that consume large amounts of power, such as electric vehicles, so-called assembled batteries in which a large number of secondary batteries are connected in parallel or in series are often used. In such an assembled battery, if some of the batteries are overcharged or overdischarged, and the batteries generate abnormal heat, in extreme cases, the batteries will ignite and spread to surrounding batteries, automobile bodies, etc. There is a danger of end. Therefore, various battery control systems that detect abnormalities such as overcharge and overdischarge by voltage measurement have been developed in the past as disclosed in Patent Document 1, for example. In this case, the battery whose abnormality is detected by the battery control system is immediately removed and replaced with a normal battery.

  However, in actual battery usage sites, the battery control system as described above is not operating normally, or even if it has a battery control system, it is often not activated. In such a case, overcharge or overdischarge cannot be detected, which may cause the battery to run out of heat, which may cause explosion or fire, resulting in a serious danger such as a fire.

By the way, as for the secondary battery, for example, in Patent Document 2, a heat storage sheet containing a latent heat storage material made of an organic compound such as polyethylene glycol, paraffinic hydrocarbon, or olefinic hydrocarbon is attached to the outer surface of the battery. In addition, a technique has been proposed in which initial heat at the time of abnormal battery heat generation is absorbed by a heat storage material to prevent rapid temperature rise of the battery and prevent thermal runaway.
Thus, if the sheet | seat containing a thermal storage material is attached to a battery, it is possible to avoid the raise of initial temperature to some extent. However, if the heat generation is extremely rapid or the amount of heat generation is extremely large, the heat storage sheet attached to the battery cannot sufficiently suppress the temperature rise, and in the worst case, it will completely lead to a fire. Cannot be prevented. In particular, when using a latent heat storage material made of an organic compound such as paraffin as shown in Patent Document 2, once it ignites, the heat storage material itself decomposes and burns with an exothermic reaction, rather expanding the fire. There is a risk of encouragement.

  On the other hand, in order to prevent the spread of fire resulting from the thermal runaway of the battery as described above, it has been conventionally performed to arrange various extinguishing agents in the vicinity of the battery. However, this is only a countermeasure at the stage where the fire has spread due to thermal runaway, and thermal runaway itself cannot be avoided.

Japanese Patent No. 4814366 JP 2009-140786 A

  The present invention has been made against the background of the above circumstances, and when abnormal heat generation occurs in the battery due to overcharge, overdischarge, etc., the battery temperature is prevented from rising suddenly due to the heat generation. An object of the present invention is to provide a secondary battery that can prevent a runaway and at the same time, can be extinguished or prevented from spreading even if it is ignited by a thermal runaway and leads to a fire. Moreover, in this invention, while providing the assembled battery comprised with such a secondary battery, the sheet-like member used for said secondary battery is provided.

As a result of intensive experiments and studies to solve the above-mentioned problems, the present inventors, as a latent heat storage material for suppressing a rapid temperature rise of the battery, are inorganic acetates or inorganic salts represented by sodium acetate. By using bicarbonate, not only can a rapid temperature rise due to abnormal heat generation of the battery be suppressed, but even if it ignites due to thermal runaway and leads to a fire, it decomposes at a high temperature accompanying the fire and releases CO ₂ gas. As a result, it was found that fire extinguishing or fire spread prevention can be effectively achieved, and the present invention has been made.

Specifically, the secondary battery of the basic aspect (first aspect) of the present invention includes a battery main body in which a positive electrode and a negative electrode are accommodated in a battery container, and is attached to the battery main body and is thermally decomposed. And a heat storage member including a latent heat storage material made of inorganic acetate or inorganic hydrogen carbonate that generates CO ₂ gas.

In such a secondary battery of the basic aspect of the present invention, if abnormal heat generation occurs in the battery body due to overcharge or overdischarge at the time of use, heat from the battery container is added to the heat storage member, and heat storage As a result of the heat absorbed by the latent heat storage material contained in the member being melted, a rapid temperature increase of the battery body can be suppressed.
In addition, if a battery ignites due to thermal runaway and a fire occurs, the heat of combustion of the fire decomposes the latent heat storage material composed of inorganic acetate or inorganic bicarbonate to generate CO ₂ gas and burn it. Obstruct the supply of oxygen necessary for Furthermore, since the decomposition reaction by heating inorganic acetate or inorganic hydrogen carbonate is an endothermic reaction, the decomposition of the heat storage material has the effect of lowering the temperature of the fire site. Together, these actions can prevent fire extinguishing or preventing fire spread.

The secondary battery of the second aspect of the present invention is characterized in that, in the secondary battery of the first aspect, sodium acetate is used as the heat storage material.
Here, sodium acetate includes its hydrate.

Sodium acetate (or a hydrate thereof) used as a latent heat storage material in the secondary battery of the second aspect has a large heat of fusion and a melting point that is abnormally high due to overcharge or overdischarge of the battery. Because it is near the initial temperature, it can absorb the heat effectively in the early stage of abnormal heat generation, and its melting point is considerably higher than room temperature, so there is little risk of melting at ambient room temperature . Furthermore, since the decomposition temperature of sodium acetate or its hydrate is close to the temperature of the combustion part at the time of a general fire, the fire extinguishment or the spread of fire is effectively prevented by the generation of CO ₂ gas and the endothermic reaction accompanying the decomposition. Can do.

  Furthermore, the secondary battery according to the third aspect of the present invention is the secondary battery according to any one of the first and second aspects, wherein the heat storage member is filled with the latent heat storage material in a sheet-like sealed container. The sheet-like heat storage member is attached in close contact with the outer surface of the battery container.

  In such a secondary battery of the third aspect, since the sheet-like heat storage member is attached to the outer surface of the battery container, there is no need to change the structure itself inside the battery body, and therefore, the change or design of the battery production line The present invention can be easily applied to existing batteries without incurring a cost increase due to changes or the like.

  The assembled battery according to the fourth aspect of the present invention is characterized in that a plurality of the secondary batteries according to any one of the first to third aspects are accommodated in a frame.

  In the assembled battery of the fifth aspect, since the heat storage member as described above is attached to the battery container of each battery in the frame, if any battery in the frame abnormally generates heat, It is possible to prevent the temperature of the battery and the surrounding battery from suddenly rising and leading to thermal runaway, and even if any battery ignites in the assembled battery and a fire occurs, immediately extinguish the fire, It is possible to prevent the spread of fire.

Furthermore, the sheet-like heat storage member for a secondary battery according to the fifth aspect of the present invention is filled with a latent heat storage material made of inorganic acetate or inorganic hydrogen carbonate that generates CO ₂ gas by thermal decomposition in a sheet-like sealed container. Thus, it is characterized in that the sheet is formed as a whole.

  According to the present invention, when abnormal heat generation occurs in the battery due to overcharge, overdischarge, etc., the battery temperature is prevented from suddenly rising due to the heat generation, thereby preventing thermal runaway and at the same time temporarily Even if a fire occurs due to a runaway, a fire can be extinguished or fire spread can be prevented.

1 is a schematic perspective view showing a secondary battery according to a first embodiment of the present invention. It is sectional drawing of an example of the sheet-like heat storage member used for the secondary battery of this invention. FIG. 5 is a schematic perspective view showing a secondary battery according to a second embodiment of the present invention. FIG. 4 is a schematic perspective view showing an assembled battery in which a number of secondary batteries shown in FIG. 3 are incorporated as a third embodiment of the present invention. FIG. 6 is a schematic cross-sectional view of a secondary battery according to a fourth embodiment of the present invention.

Embodiments of the present invention will be described below in detail with reference to the drawings.
FIG. 1 shows a secondary battery according to a first embodiment of the present invention.
In this embodiment, the battery main body 1 includes, for example, one or two or more positive electrodes (not shown) and one or two or more positive electrodes as one or two or more battery cell components in a battery container 3 having a flat and thin box shape. A negative electrode and an electrolyte are accommodated. From one surface 3A of the battery case 3 (which corresponds to the upper surface in the example shown in the figure, this surface is hereinafter referred to as the upper surface 3A), a pair of electrode terminals (which are respectively connected to the positive electrode and the negative electrode in the battery container 3) (Positive terminal and negative terminal) 5A and 5B protrude. The configuration so far may be the same as that of a conventional secondary battery such as a lithium ion battery, and the details thereof are omitted.

The sheet-like heat storage member 7 that is characteristic of the present invention is adhered to one wide side surface 3B of the outer surfaces of the battery container 3 in a close contact state. As shown in FIG. 2, the sheet-like heat storage member 7 is made of inorganic acetate or inorganic hydrogen carbonate that generates CO ₂ gas by thermal decomposition in the inner space of a flat and hollow sheet-like sealed container 9 as a whole. The latent heat storage material 11 is filled and sealed.
Here, in the example of FIG. 2, the sheet-like sealed container 9 is formed by, for example, bonding or fusing the peripheral portions of two thin films 9A and 9B made of, for example, polyvinyl chloride, polyethylene, polypropylene, and aluminum laminate film. Joined to form a flat bag as a whole. And the outer surface of one thin film 9B of the two thin films 9A and 9B is adhered to the side surface of the battery container 3 with an appropriate adhesive.

The material of the sheet-like airtight container 9 in the sheet-like heat storage member 7 is a temperature range (60 to 120) that is lower than the decomposition temperature due to the heating of the latent heat storage material and is optimal for storing heat during abnormal heat generation due to overdischarge or overcharge. Those having a melting point higher than about 0 ° C. are desirable. Further, the material of the sheet-like sealed container 9 is preferably a soft resin having flexibility so that it can be attached in a state of being in close contact with the outer surface of the battery container 3, but in some cases, a relatively hard one is allowed. . Specifically, as the resin having flexibility, in addition to the above-mentioned polyvinyl chloride, polyvinylidene chloride, polypropylene, polyethylene, etc., and relatively hard ones such as epoxy resin, nylon, polyethylene terephthalate, acrylic resin, An aluminum laminated film in which the surface of a polyethylene or polypropylene sheet is laminated with an aluminum foil can be used.
Here, in the example of FIG. 2, the structure of the sheet-like airtight container 9 is such that two thin films 9A and 9B are overlapped and the peripheral edge is joined, but the both ends of the tube are closed and processed into a flat shape. It may also be formed into a flat box shape.

The latent heat storage material 11 filled in the internal space of the sheet-like airtight container 9 may be made of an inorganic acetate or an inorganic hydrogen carbonate that generates CO ₂ gas by thermal decomposition, and particularly has a temperature of about 60 ° C. It is appropriate to start melting when heated to a temperature and exhibit a function of storing heat by latent heat. Therefore, it is desirable to use a material having a melting point of about 55 ° C. or more as the latent heat storage material 11.
Here, when the melting temperature of the latent heat storage material is less than 50 ° C., particularly less than 40 ° C., even if the battery main body does not generate abnormal heat due to overcharge or overdischarge, the latent heat storage material depends on the ambient temperature such as the battery compartment temperature of the automobile. May melt. In this case, since the heat stored in the latent heat storage material is released during cooling, there is a disadvantage that the battery is held at a high temperature for a long time.
On the other hand, if the melting point of the latent heat storage material is a high temperature exceeding about 120 ° C., particularly about 150 ° C., even if abnormal heat generation occurs due to overcharge or overdischarge, the latent heat storage material melts at the initial stage of abnormal heat generation. Therefore, it is difficult to suppress an initial temperature rise due to abnormal heat generation.
Therefore, it is desirable to select a latent heat storage material having a melting point or endothermic temperature in the range of 40 to 150 ° C. Also within that range, those having a melting point or endothermic temperature in the range of 50 to 120 ° C. are preferred.
On the other hand, in order to fully demonstrate the fire extinguishing and fire spread prevention functions when a thermal runaway occurs. It is desirable to select a latent heat storage material having a decomposition temperature in the range of about 200 to 400 ° C. That is, if the decomposition temperature is less than about 200 ° C, it may decompose at a stage where a fire has not yet occurred, and there is a risk that fire extinguishing against fire and prevention of fire spread may not be expected, while if the decomposition temperature exceeds about 400 ° C, There is a risk that the latent heat storage material will not be decomposed in the early stage of the fire, and the fire extinguishing and fire spread prevention functions cannot be fully exhibited.

  As a substance that satisfies these preferable conditions and has a sufficiently large latent heat storage amount (heat of fusion), there is sodium acetate or its hydrate, which is an inorganic carbonate. It is desirable to use hydrates.

Sodium acetate is represented by the chemical formula CH ₃ COONa, and its hydrate is typically trihydrate, that is, CH ₃ COONa · 3H ₂ O.
Here, the melting point of sodium acetate trihydrate is 58 ° C., the heat of fusion is 264 kJ / kg, and the heat of fusion of the paraffin-based latent heat storage material described in Patent Document 2 (157 kJ). / Kg). Further, when heated, this sodium acetate trihydrate becomes anhydrous at about 120 to 250 ° C., and further decomposes as an endothermic reaction at 324 ° C. to generate CO ₂ gas. The decomposition reaction is as shown in the following formula (1).
CH ₃ COONa · 3H ₂ O → NaCH ₃ + CO ₂ ↑ + 3H ₂ O (1)
The anhydrous sodium acetate has a melting point of 324 ° C. and is unsuitable as it is, but the melting point is lowered by dissolving in 3 mol or more of water, and it is used in the same manner as sodium acetate trihydrate. It is possible. That is, the melting point of an aqueous solution in which sodium acetate anhydride is dissolved in water can be adjusted to 40 ° C to 58 ° C. In this case, the decomposition reaction follows the formula (1), and CO ₂ gas is generated in accordance with the decomposition as described above.
Accordingly, sodium acetate (anhydride) and sodium acetate trihydrate are both suitable as the latent heat storage material in the present invention.

Examples of latent heat storage materials other than sodium acetate or hydrates thereof include inorganic hydrogen carbonates such as sodium hydrogen carbonate (NaHCO ₃ ), calcium hydrogen carbonate (Ca (HCO ₃ ) ₂ ), and potassium hydrogen carbonate (KHCO ₃ ). Can be used.
Here, sodium hydrogen carbonate has a melting point of 270 ° C., but the aqueous solution gradually undergoes endothermic decomposition at 50 ° C. or higher to generate CO ₂ gas. The powder (solid) is decomposed as an endothermic reaction at 270 ° C. according to the following equation (2) to generate CO ₂ gas.
2NaHCO ₃ → Na ₂ CO ₃ + CO ₂ ↑ + H ₂ O (2)
Therefore, sodium bicarbonate can be used as a mixed slurry of the aqueous solution and powder.
In addition, calcium bicarbonate does not exist as a solid but exists as an aqueous solution, so in practice calcium carbonate is dissolved in water and used. The melting point of calcium carbonate is 825 ° C., but the aqueous solution is decomposed as an endothermic reaction by the following formula (3) at 100 to 200 ° C. to generate CO ₂ gas.
Ca (HCO ₃ ) → CaCO ₃ + CO ₂ ↑ + H ₂ O (3)
Furthermore, potassium bicarbonate has a melting point of 100 ° C. to 200 ° C., and decomposes as an endothermic reaction by the following formula (4) at 100 ° C. or higher to generate CO ₂ gas.
2KHCO ₃ → K ₂ CO ₃ + CO ₂ ↑ + H ₂ O (4)
Therefore, any of these can be used as a latent heat storage material in the present invention as a slurry in which a solid is dispersed in an aqueous solution or water.
On the other hand, as the inorganic acetate, potassium acetate hemihydrate (melting point 42 ° C.), magnesium acetate (melting point 80 ° C.), lithium acetate (melting point 70 ° C.), etc. can be used in addition to the sodium acetate. It is.

  The form of the latent heat storage material 11 filled in the sheet-like sealed container 9 is not particularly limited, and is dissolved in an appropriate solvent such as powder or water depending on the type and physical properties of the latent heat storage material. It is possible to apply a solution or slurry, or a bulk shape obtained by compression molding a powder.

While the secondary battery of the first embodiment as described above is actually used, if abnormal heat generation occurs in the battery body 1 due to overcharge or overdischarge, the heat from the battery container 3 is changed to the side surface. 3B is added to the sheet-like airtight container 9, and the inner heat storage material 11, for example, sodium acetate trihydrate, is heated. And if the temperature becomes more than melting | fusing point of the Banetsu heat storage material 11, the Banetsu heat storage material 11 will fuse | melt, the heat | fever of abnormal heat_generation | fever can be absorbed with the melting latent heat, and a rapid temperature rise can be suppressed.
Furthermore, even if the thermal runaway had ignited occurs, the presumptuous heat storage material 11 at high temperature by combustion heat is decomposed and generates CO ₂ gas, the supply of oxygen to the CO ₂ gas combustion point At the same time, the endothermic reaction at the time of decomposition suppresses the increase in the ambient temperature and exhibits the effect of extinguishing fire or preventing the spread of fire.

  FIG. 3 shows a secondary battery according to the second embodiment of the present invention. In the second embodiment, the difference from the first embodiment is only the attachment position of the sheet-like heat storage member 7 in the battery container 3, and therefore, explanations other than the matters related thereto are omitted.

In FIG. 3, the sheet-like heat storage member 7 is adhered to the upper surface 3A of the battery container 3, that is, the surface provided with the electrode terminals (positive electrode terminal and negative electrode terminal) 5A, 5B in a close contact state.
Here, heat at the time of abnormal heat generation due to overcharge or overdischarge is mainly transmitted from the positive electrode and the negative electrode (not shown) in the battery container 3 to the electrode terminals 5A and 5B. It is usual that the upper surface 3A provided with is heated most rapidly to a high temperature. Therefore, as shown in FIG. 3, by sticking the sheet-like heat storage member 7 to the upper surface 3A, the heat of abnormal heat generation due to overcharge or overdischarge is immediately absorbed, and the battery body 1 is rapidly heated. The suppression effect is increased.

FIG. 4 shows an assembled battery 15 incorporating a large number of the secondary batteries (battery body 1) shown in FIG. 3 as a third embodiment of the present invention.
In FIG. 4, a large number of battery main bodies 1 are accommodated in a frame 13 that is rectangular as a whole, and an assembled battery 15 is configured as a whole. One side of the frame 13 (upper surface in the illustrated example) is open. The arrangement state of each battery body 1 is determined so that the surface (upper surface 3A) provided with the electrode terminals 5A and 5B in each battery body 1 faces upward (the open side of the frame 13). And in each battery main body 1, the sheet-like heat storage member 7 is affixed on the upper surface 3A provided with the electrode terminals 5A and 5B in the battery container 3, respectively, as shown in FIG. In an actual assembled battery, the electrode terminals of each battery body 1 are connected in parallel or in series by a conductive wire, but the conductive wire is omitted in FIG.
Thus, even in the assembled battery 15 comprising a large number of batteries, each battery is provided with the sheet-like heat storage member 7, thereby suppressing a rapid temperature rise during abnormal heat generation due to overcharge or overdischarge as described above. Thus, the occurrence of thermal runaway can be prevented, and even if the thermal runaway occurs and the fire is ignited, fire extinguishing or fire prevention can be prevented.

FIG. 5 shows a secondary battery according to a fourth embodiment of the present invention.
In this embodiment, the sheet-like heat storage member 7 filled with the latent heat storage material 11 is arranged inside the battery container 3 in the battery body 1. That is, the battery main body 1 shown in FIG. 5 has a plurality of positive plates 17, a plurality of separators 19, and a plurality of negative plates 21 inside the battery container 3 in which the electrolyte is accommodated, as in a normal secondary battery. Are stacked alternately to form one battery cell 23 by the adjacent positive electrode plate 17, separator 19, and negative electrode plate 21, and a stacked battery including a plurality of battery cells 23 is formed as a whole. A sheet-like heat storage member 7 in which a latent heat storage material 11 made of inorganic acetate or inorganic hydrogen carbonate that generates CO ₂ gas by thermal decomposition is filled in a sheet-like airtight container 9 similar to the above is close It is provided in a state of being sandwiched between two separators 17. Thus, even when the sheet-like heat storage member 7 is arranged inside the battery body 1, the latent heat storage material 11 of the sheet-like heat storage member 7 can exhibit the functions already described.
In the example of FIG. 5, the sheet-like heat storage member 7 is sandwiched between the separators 17. However, in addition, for example, the sheet-like heat storage member 7 may be arranged along the inner surface of the battery container 3. Is possible to change,

  Examples of the present invention will be described below.

[Example 1]
Example 1 is an example in which sodium acetate trihydrate powder was applied as a latent heat storage material.
That is, the powder of sodium acetate trihydrate was sealed in a sheet-like airtight container (wall thickness is 0.1 mm) made of a polyethylene sheet as shown in FIG. This was affixed to the side of a battery body (lithium ion battery) as shown in FIG. 1 using a heat-resistant double-sided tape as an adhesive. And when it overcharged actually and the overheating state of the temperature of 60 degreeC or more was produced, it was confirmed that the rapid temperature rise is suppressed. In addition, when the battery body was overcharged until the battery body was out of control, and the battery body was ignited, the sheet-like sealed container partially melted, and at the same time, the CO ₂ gas generated by decomposition of sodium acetate spouted out, It was confirmed that it was weakened.

[Example 2]
Example 2 is an example in which an aqueous solution of sodium acetate is applied as a latent heat storage material.
That is, a 60% by weight aqueous solution of sodium acetate was sealed in a sheet-like airtight container (wall thickness is 0.1 mm) made of a polyethylene sheet as shown in FIG. This was stuck to the side of a lithium ion battery as shown in FIG. 1 using a heat-resistant double-sided tape as an adhesive. And when it overcharged actually and the overheating state of the temperature of 60 degreeC or more was produced, it was confirmed that the rapid temperature rise is suppressed. In addition, when the battery body was overcharged until the battery body was out of control, and the battery body was ignited, the sheet-like sealed container partially melted, and at the same time, the CO ₂ gas generated by decomposition of sodium acetate spouted out, It was confirmed that it was weakened.

Example 3
Example 3 is an example in which potassium acetate 1.5 hydrate powder was applied as a latent heat storage material.
That is, the powder of potassium acetate 1.5 hydrate was enclosed in a sheet-like airtight container (wall thickness is 0.1 mm) made of a polyethylene sheet as shown in FIG. This was stuck to the side of a lithium ion battery as shown in FIG. 1 using a heat-resistant double-sided tape as an adhesive. And when it overcharged actually and the overheating state of the temperature of 60 degreeC or more was produced, it was confirmed that the rapid temperature rise is suppressed. Further, when the battery main body was overcharged until the thermal runaway occurred, and the battery main body was ignited, the sheet-like sealed container partially melted, and at the same time, the CO ₂ generated by decomposition of potassium acetate · 1.5 hydrate. It was confirmed that gas was ejected and the fire was weakened.

Example 4
Example 4 is an example in which a slurry obtained by mixing an aqueous solution of sodium hydrogen carbonate (NaHCO ₃ ) and powder as a latent heat storage material is applied.
That is, a 40% by weight aqueous solution slurry of sodium bicarbonate (NaHCO ₃ ) was sealed in a sheet-like airtight container (wall thickness is 0.1 mm) made of a polyethylene sheet as shown in FIG. 2 to obtain a sheet-like heat storage member. . This was stuck to the side of a lithium ion battery as shown in FIG. 1 using a heat-resistant double-sided tape as an adhesive. And when it overcharged actually and the overheating state of the temperature of 60 degreeC or more was produced, it was confirmed that the rapid temperature rise is suppressed. Moreover, when the battery body was overcharged until thermal runaway occurred, and the battery body was ignited, the sheet-like sealed container partially melted, and at the same time, CO ₂ gas generated by decomposition of sodium hydrogen carbonate was blown out, and the fire Was confirmed to be weakened.

  The preferred embodiments and examples of the present invention have been described above. However, these embodiments and examples are merely examples within the scope of the present invention, and do not depart from the spirit of the present invention. Thus, addition, omission, replacement, and other changes of the configuration are possible. That is, the present invention is not limited by the above description, is limited only by the scope of the appended claims, and can be appropriately changed within the scope.

DESCRIPTION OF SYMBOLS 1 Battery main body 3 Battery container 5A, 5B Electrode terminal 7 Sheet-like heat storage member 9 Sheet-like airtight container 11 Latent heat storage material 13 Frame 15 Assembly battery

Claims (5)

A battery body in which a positive electrode and a negative electrode are housed in a battery container;
A heat storage member including a latent heat storage material made of inorganic acetate or inorganic hydrogen carbonate attached to the battery body and generating CO ₂ gas by thermal decomposition;
A secondary battery comprising:   The secondary battery according to claim 1, wherein sodium acetate is used as the latent heat storage material.   The heat storage member has a structure in which the latent heat storage material is filled in a sheet-like airtight container, and is formed so as to form a sheet shape as a whole, and the sheet-like heat storage member is in close contact with the outer surface of the battery container. The secondary battery according to claim 1, wherein the secondary battery is attached.   An assembled battery comprising a plurality of secondary batteries according to any one of claims 1 to 3 housed in a frame. The sheet-like airtight container is filled with a latent heat storage material made of inorganic acetate or inorganic hydrogen carbonate that generates CO ₂ gas by thermal decomposition, and is made to form a sheet as a whole. A sheet-like heat storage member for a secondary battery.

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