JP2022119679A - Partition member and battery pack - Google Patents

Abstract

To provide a partition member and a battery pack that normally exhibit good elasticity and pressure resistance, efficiently transfer the heat generated from an adjacent unit cell to the adjacent unit cell, and can prevent a chain of damage between cells when the adjacent unit cell is damaged and there is a risk that the damage may spread to the entire battery pack in a chain reaction.SOLUTION: A partition member that has a thickness direction and a plane direction orthogonal to the thickness direction, and partitions between unit cells or between a unit cell and a member other than the unit cell in the thickness direction, and includes a heat transfer control layer, a compressible control layer, and an outer body housing them.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present invention relates to a partition member and an assembled battery.

In recent years, the use of secondary batteries as a power source for vehicles has increased rapidly. For the purpose of increasing energy consumption, etc., studies are underway to increase the energy density of secondary batteries. On the other hand, the safety of secondary batteries tends to conflict with their energy density, and the higher the energy density of a secondary battery, the lower the safety. For example, in a secondary battery installed in an electric vehicle with a cruising range of several hundred kilometers, if the secondary battery is damaged due to overcharging, internal short circuit, etc., the battery surface temperature exceeds several hundred degrees Celsius, reaching 1000 degrees Celsius. It may be more than that.

Secondary batteries used as power sources for vehicles and the like are generally used as an assembled battery consisting of a plurality of single cells. Adjacent single cells may be damaged by the heat generation, and the damage may spread to the entire assembled battery in a chain reaction. In order to prevent such a chain of damage between the cells, various techniques have been proposed in which a partition member is provided between the cells and the damaged cells are cooled.

For example, there is a module in which a partition member having a configuration in which a cooling agent such as water is put in a sheet-like bag is installed between unit cells (for example, Patent Document 1). According to this module, in addition to efficiently transferring the heat generated from the adjacent cells to the adjacent cells, if the adjacent cells are damaged and the surface temperature of the battery reaches a high temperature, the battery inside the bag will be released from the unsealed portion. Water is released and can cool the damaged battery. In addition, there is a partition member having a structure in which a sheet-like bag is filled with a porous body impregnated with a cooling agent such as water (for example, Patent Document 2).

JP 2014-157747 A JP 2011-108617 A

As a result of a detailed study of these conventional techniques, the inventors of the present invention have found the following problems. That is, the unit cells in the assembled battery are subjected to a confining pressure when the assembled battery is manufactured. In addition, when a cell is charged, the electrodes in the cell expand, so the casing also expands and presses adjacent members. In addition, pressure is also applied to the single cell due to expansion due to generation of gas from the electrolytic solution in the single cell due to repeated use. For these reasons, the partition member installed between the cells is required to have pressure resistance. However, the partition members disclosed in Patent Literatures 1 and 2 have not been sufficiently studied with respect to pressure resistance.

On the other hand, the present inventor proposed a partition member including a heat insulating material holding liquid and an exterior body for accommodating them. This partition member has a characteristic that the thermal resistance switches between before and after the temperature (opening temperature) at which the vapor pressure of the liquid exceeds the bursting strength of the outer package. When the temperature is lower than the opening temperature, the liquid retained inside the exterior material exhibits a low thermal resistance. Due to this characteristic, the partition member that is in contact with the unit cell that has abnormally increased temperature due to overcharging, internal short circuit, or the like opens, and its high thermal resistance makes it possible to suppress heat conduction to the adjacent unit cell. On the other hand, the partition member between the cells other than the abnormal cell has a low thermal resistance, and it is possible to suppress the temperature rise of each battery due to the heat transfer from the abnormal cell. .

Under the above circumstances, the partition member is required to exhibit good elasticity and good pressure resistance in order to absorb the expansion of the cells and maintain the performance of the cells. On the other hand, in addition to efficiently transferring the heat generated from adjacent cells to neighboring cells, there is also the risk that the temperature of adjacent cells will rise abnormally, causing a chain reaction of abnormal temperature rises spreading to the entire assembled battery. In the event of such an abnormality, it is required to prevent a chain of temperature rises between cells.
That is, it is an object of the present invention to provide a partition member capable of satisfying both the performance required for normal operation and the performance required for abnormal operation at a high level, and to provide an assembled battery using the partition member.

As a result of intensive studies aimed at solving the above problems, the inventors of the present invention solved the above problems by incorporating a layer for controlling heat transfer and a layer for controlling compressibility into a partition member for an assembled battery. After discovering that it is possible, the following invention was completed. That is, the present invention is as follows.

[1] A partition member having a thickness direction and a surface direction orthogonal to the thickness direction, and partitioning between the cells or between the cells and members other than the cells in the thickness direction, the heat transfer control layer, A partition member including a compressible control layer and an outer body housing them.
[2] The compressibility control layer is a tray-shaped member having a plurality of recesses, and the heat transfer control layer is composed of a paste containing at least one selected from the group consisting of heat-resistant particles and heat-resistant fibers and a liquid. The partition member according to [1] above.
[3] The partitioning member according to [2] above, wherein the concave portion of the tray-like member is filled with the paste.
[4] The partition member according to the above [2] or [3], wherein the liquid is water.
[5] The partition member according to [1] above, wherein the compressibility control layer is a tray-shaped member having a plurality of recesses, and the heat transfer control layer is made of heat-resistant particles.
[6] The partition member according to any one of [2] to [5] above, wherein the tray-shaped member is made of a thermoplastic resin.
[7] The partition member according to the above [6], wherein the thermoplastic resin is an olefin resin.
[8] The partition member according to the above [7], wherein the olefinic resin is polypropylene.
[9] The partition member according to any one of [2] to [8] above, wherein the heat-resistant particles are at least one selected from the group consisting of calcium silicate and zeolite.
[10] An assembled battery including the partition member according to any one of [1] to [9] above and a plurality of cells.

According to the present invention, in normal times, it exhibits good elasticity and pressure resistance, can efficiently transfer heat generated from adjacent cells to adjacent cells, and can damage adjacent cells, It is possible to propose a partition member and an assembled battery that can prevent a chain of damages between cells in an abnormal situation where damage may spread to the entire assembled battery in a chain reaction.

1 is a photograph showing one aspect of a compressible control layer in the present invention. FIG. 3 is a conceptual diagram showing an example of the partition member of the present invention; FIG. 4 is a conceptual diagram showing another example of the partition member of the present invention; 1 is a conceptual diagram showing an assembled battery of the present invention; FIG. FIG. 2 is a plan view showing an example of a cell; FIG. 6 is a front view of the cell of FIG. 5; FIG. 6 is a side view of the cell of FIG. 5; It is a conceptual diagram of a thermal insulation evaluation apparatus.

An example of an embodiment of the present invention will be described in detail below. However, the present invention is not limited to the embodiments described below, and can be arbitrarily modified without departing from the gist of the present invention.
In this specification, when "X to Y" (where X and Y are arbitrary numbers), unless otherwise specified, it means "X or more and Y or less" and "preferably larger than X" or "preferably is smaller than Y'. In addition, when described as "X or more" (X is any number), unless otherwise specified, it includes the meaning of "preferably greater than X", and when described as "Y or less" (Y is any number) , also includes the meaning of "preferably smaller than Y" unless otherwise specified.

[Partition member]
The partition member of the present invention is a member that has a thickness direction and a plane direction perpendicular to the thickness direction, and partitions between the cells or between the cells and members other than the cells in the thickness direction. Here, the “members other than the unit cells” is, for example, a housing that has a bottom surface and four side surfaces and accommodates the unit cells and partition members that constitute the assembled battery.
The partition member of the present invention includes a heat transfer control layer, a compressible control layer, and an exterior housing them. There may be multiple layers of each of the heat transfer control layer and the compressibility control layer in one partition member.

<Heat transfer control layer>
The partition member of the present invention is characterized by having a heat transfer control layer. The heat transfer control layer can efficiently transfer the heat generated from the adjacent cells to the neighboring cells under normal conditions, and at the time of abnormality, it exhibits heat insulating properties to prevent heat transfer to the adjacent cells. This is the controlling layer. Specifically, a heat-resistant particle or a heat-resistant particle-liquid paste (hereinafter sometimes referred to as "heat-resistant particle paste") is preferably used.
In the present invention, it is particularly preferable to use a heat-resistant particle paste. The liquid contained in the heat-resistant particle paste evaporates when one of the cells heats up abnormally. can also dissipate heat.
On the other hand, heat-resistant particles may be used and no liquid may be used, and by forming a partition member in combination with the compressibility control layer and the exterior body, the powder absorbs the expansion of the unit cell. be able to. Moreover, the pressure resistance is high, and the partition member does not rupture or the like when the cell expands.

(Heat-resistant particles and heat-resistant fibers)
The heat-resistant particles are not particularly limited as long as the effect of the present invention is exhibited, but inorganic particles are preferable. , cement, perlite, fumed silica and aerogels. Among these, silica particles, alumina particles, calcium silicate, zeolite and vermiculite are preferable, and calcium silicate and zeolite are particularly preferable from the viewpoint of allowing more liquid to be contained in particles and between particles.
Among the types of calcium silicate, xonotlite, tobermorite, wollastonite and gyrolite are preferred, and gyrolite is particularly preferred. Gyrolite, which has a petal-like structure, maintains its porous structure even when it is compressed and deformed, so it has excellent water retention. Clay minerals are mainly magnesium silicate (including talc and sepiolite), montmorillonite and kaolinite. The particle diameter of the heat-resistant particles is preferably 1/5 or less of the thickness of the heat transfer control layer. These heat-resistant particles can be used singly or in a mixed state.
Moreover, the heat-resistant fiber is not particularly limited as long as the effect of the present invention is exhibited, and examples thereof include glass fiber, alumina fiber, rock wool, and the like. The fiber diameter of the heat-resistant fiber is preferably 1/5 or less of the thickness of the heat transfer control layer. These heat-resistant fibers can be used either singly or in a mixed state.
When the heat-resistant fibers are pasted together with the liquid, the fiber diameter and fiber length are not particularly limited as long as the fiber diameter and fiber length can be pasted. In general, a fiber diameter that is somewhat small and a fiber length that is relatively short is advantageous for pasting.
Heat-resistant particles and heat-resistant fibers can also be used in combination.

(liquid)
As the liquid for making the particles into a paste, any liquid may be used as long as it has thermal conductivity and can efficiently transfer the heat generated from the cell to adjacent cells. The liquid preferably has a boiling point of 80° C. or higher and 250° C. or lower at normal pressure (1 atm), more preferably a liquid whose boiling point is 100° C. or higher and 150° C. or lower at normal pressure.
The liquid preferably contains, for example, at least one selected from the group consisting of water, alcohols, esters, ethers, ketones, hydrocarbons, fluorine compounds and silicone oils. These may be used alone or as a mixture of two or more. As the liquid, water is particularly preferable because it has a large heat of vaporization and is widely available.

Alcohols that can be used as liquids include alcohols containing 3 to 8 carbon atoms such as propanol, isopropanol, butanol, benzyl alcohol and phenylethyl alcohol, alkylene glycols such as ethylene glycol and propylene glycol, and glycerin. Dihydric or higher alcohols and the like are included. These may be used alone or as a mixture of two or more.

Esters that can be used in the liquid include alkyl aliphatic carboxylic acid esters, alkyl carbonic acid diesters, alkyl oxalic acid diesters, and fatty acid esters of ethylene glycol. These may be used alone or as a mixture of two or more.

Ethers that can be used for the liquid include n-butyl ether, n-propyl ether, isoamyl ether and the like. These may be used alone or as a mixture of two or more.

Examples of ketones that can be used for the liquid include methyl ethyl ketone and diethyl ketone. These may be used alone or as a mixture of two or more.

Hydrocarbons that can be used for the liquid include heptane, octane, nonane, decane, toluene, and xylene. These may be used alone or as a mixture of two or more.

Fluorinated compounds that can be used in the liquid include refrigerant 1,1,2,2,3,3,4-heptafluorocyclopentane (HFC-c447ef), 1,1,1,2,2,3, 3,4,4,5,5,6,6-tridecafluorooctane (HFC-76-13sf) and the like. These may be used alone or as a mixture of two or more.

Examples of silicone-based oils that can be used as liquids include methylpolysiloxane, methylphenylpolysiloxane, cyclic methylsiloxane, and modified silicone oils such as silicone polyether copolymers. These may be used alone or as a mixture of two or more.

In addition, the liquid may contain additives such as antifreeze agents, preservatives, pH adjusters and surfactants. It should be noted that the surfactant can adjust the compatibility when the heat-resistant particle paste or heat-resistant fiber paste is filled into the tray-shaped member. Also, the liquid may contain a gelling agent and be gelled. The above additives may be used alone or as a mixture of two or more. What is included in the liquid is not limited to this, and can be added as necessary.

The above-described heat transfer control layer is contained in an exterior body, which will be described later. When heat-resistant particle paste or powdery heat-resistant particles are used, it is preferable to have a member for holding them. The member is preferably a tray-shaped member having a function as a compressibility control layer, which will be described later.

<Compressibility control layer>
The compressibility control layer in the present invention is a layer that has a function of absorbing expansion due to normal charging of the unit cell, expansion due to deterioration of the unit cell, expansion during use of the battery at high temperatures, and the like. Specifically, a tray-shaped member having a plurality of concave portions (hereinafter sometimes referred to as “tray-shaped member”) as shown in FIG. 1 can be used. It is preferable that the heat-resistant particles or the heat-resistant particle paste can be retained by having such recesses. Moreover, by using the compressibility control layer, it is possible to control the compressibility as a partition member while using heat-resistant particles, heat-resistant fibers, heat-resistant particle paste, and heat-resistant fiber paste, which is preferable.
That is, the tray-shaped member has the function of filling the recesses of the tray-shaped member with heat-resistant particles or heat-resistant particle paste suitable for the heat transfer control layer and holding the same, and also has the function of the compressibility control layer.
In the present invention, even if the tray-shaped member is filled with a heat-resistant particle paste or the like, the tray-shaped member is defined as a compressibility control layer, and the heat-resistant particle paste or the like filled in the recesses thereof controls heat transfer. Defined as a layer. The heat-resistant particles (powder) or heat-resistant particle paste may be filled so that the concave portion of the tray-shaped member is filled (see FIG. 2), or may be filled up to a part of the depth of the concave portion. good too. Moreover, it is not necessary to fill all the concave portions with heat-resistant particles or heat-resistant particle paste. Furthermore, as long as the tray-like member and the heat-resistant particles and the like are loaded in the exterior body, the heat-resistant particles and the like may overflow from the concave portion of the tray-like member (see FIG. 3).

The size of the concave portion of the tray-shaped member is not particularly limited as long as the effect of the present invention is exhibited. A range is preferred, a range of 10 to 95% is more preferred, and a range of 20 to 90% is even more preferred. When the area of the recesses is equal to or greater than the above lower limit, a sufficient amount of the heat-resistant particle paste or the like can be retained in the recesses, so that the control of heat transfer and the heat insulation effect can be maintained. On the other hand, if it is equal to or less than the above upper limit, sufficient strength of the tray-like member is ensured, and good elasticity is obtained. Further, when the pressure is equal to or less than the above upper limit, when the partition member is pressurized, the internal pressure of the partition member is less likely to increase, and the pressure resistance of the partition member is improved.
The depth of the concave portion is also not particularly limited, but is preferably in the range of 0.1 to 20 mm, more preferably in the range of 0.5 to 10 mm, and more preferably in the range of 0.8 to 7 mm. is more preferred. When it is at least the above lower limit, a sufficient amount of the heat-resistant particle paste or the like can be retained in the recess, so that heat transfer control and heat insulating effect are maintained. On the other hand, when it is equal to or less than the above upper limit, sufficient strength of the tray-shaped member is ensured, good elasticity is obtained, and the assembled battery can be made compact. Further, when the thickness is equal to or less than the above upper limit, more expansion of the cells can be absorbed.

The shape of the concave portion is also not particularly limited, and may be square as shown in FIG. may be Also, the shapes of the recesses may not all be the same shape, but may be a combination of different shapes.
Also, the number of recesses is not particularly limited, and is not particularly limited as long as it has the above-mentioned area ratio, and it is usually about 0.1 to 5 per unit area (1 cm ² ). It is preferably in the range of 0.25 to 2.
The thickness (sheet thickness) of the tray-shaped member is preferably in the range of 50 to 1000 μm, more preferably in the range of 100 to 500 μm. When the thickness of the tray-shaped member is equal to or greater than the above lower limit value, sufficient elasticity can be obtained. Efficiency can be improved. Moreover, it also leads to compactization of the assembled battery.
Further, the recess may have a through hole in the thickness direction of the member. The ratio of the area occupied by the through holes to the area of the recesses is preferably about 10 to 100%, more preferably 50 to 90%. Due to the presence of the through-holes, a larger amount of heat-resistant particle paste or the like can be held, and heat transfer control and heat insulation effects can be enhanced. When the ratio of the area occupied by the through-holes to the area of the recesses is at least the above lower limit, a higher heat transfer control and heat insulating effect can be obtained. etc. is improved.

The material of the tray-shaped member is preferably a thermoplastic resin because it has good elasticity and excellent workability. Examples include olefin resins such as polyethylene and polypropylene, polyethylene terephthalate (PET), and polyethylene. Examples include polyester resins such as naphthalate (PEN), polystyrene (PS), and the like. Silicon rubber and its foam can also be used. Among these, olefin resins are preferred, and polypropylene is particularly preferred, from the viewpoint of versatility, cost, and the like. These resins may also contain heat-resistant fillers such as alumina particles and glass fibers.

The method for producing the tray-shaped member is not particularly limited. Injection molding or the like in which molten resin is poured is preferably used.

<Exterior body>
The outer body has a peripheral portion to be sealed, and accommodates the heat transfer control layer and the compressible control layer in an internal space formed by sealing. The exterior body is flexible and deformable in accordance with the expansion of the cell. In addition, the exterior body can be restored to its original state when the cells are shrunk. Specifically, when the battery is charged and expands, it is compressed to absorb the expansion, and when the battery is discharged and contracted, it returns to its original state.
As the exterior body, a resin sheet, a resin film, or the like can be applied. The heat transfer control layer and the compressibility control layer are sealed by heat-sealing or bonding the peripheral edge of the exterior body with which the contact is made.

As the exterior body, for example, one made of resin or metal can be used. A laminate of a metal foil and a resin is preferred because of its high heat resistance and strength. As the laminate of metal and resin, a laminate of three or more layers including a resin layer, a metal layer, and a resin sealant layer is preferable.

The metal forming the metal foil is preferably at least one of aluminum, copper, tin, nickel, stainless steel, lead, tin-lead alloy, bronze, silver, iridium, and phosphor bronze. Specific examples include aluminum foil, copper foil, tin foil, nickel foil, stainless steel foil, lead foil, tin-lead alloy foil, bronze foil, silver foil, iridium foil and phosphor bronze foil. In particular, aluminum foil, copper foil and nickel foil are preferable, and aluminum foil is more preferable.

At least one of a thermosetting resin and a thermoplastic resin can be used as the resin, and a thermoplastic resin is particularly preferable. Examples of resins include polyethylene, polypropylene, polystyrene, nylon, acrylic, epoxy resin, polyurethane, polyetheretherketone, polyethylene terephthalate, polyphenylsulfide, polycarbonate, and aramid. In particular, at least one selected from polypropylene, nylon, and polyethylene terephthalate is preferred.

Although the thickness of the outer package is not particularly limited, it is, for example, 5 μm to 200 μm. In the case of the laminate (laminate), the metal foil can be 3 μm to 50 μm, and the resin layer can be 2 μm to 150 μm. Thereby, the heat resistance and low water vapor permeability of the metal foil can be exhibited, and the sealing performance can be improved by the resin.

In addition, the heat transfer control layer and the compressibility control layer are hermetically sealed (sealed) in the exterior body by joining the peripheral edge portions of the two exterior bodies in an annular shape by heat-sealing, bonding, or the like. Alternatively, one exterior body may be folded and its peripheral edge portion may be joined by heat fusion, adhesion, or the like, and the heat transfer control layer and the compressibility control layer may be hermetically sealed (sealed). The exterior body preferably has flexibility (elasticity), but may not have flexibility.

It is preferable that the internal air pressure of the exterior body is lower than the external air pressure from the viewpoint of sufficiently increasing the opening temperature. For this reason, it is particularly preferable to vacuum-seal when sealing the exterior body.

[Assembled battery]
An assembled battery of the present invention includes the partition member of the present invention and a plurality of cells. More specifically, as shown in FIG. 4, a plurality of unit cells 200 and a partition member 1 for partitioning the unit cells 200 are stacked and housed in a housing 300, for example. The partition member 1 is provided at least between the unit cells 200 constituting the assembled battery 100 to prevent the unit cells 200 from coming into contact with each other. The partition member can also be used as a partition member (1A) for partitioning the unit cells 200 and other members (the bottom of the housing in FIG. 4) other than between the unit cells 200. FIG.

As described above, the partition member 1 is composed of a heat transfer control layer, a compressibility control layer, and an exterior body that accommodates these layers. The compression elastic modulus of the partition member in the thickness direction is preferably in the range of 0.1 to 20 MPa. By setting the compressive elastic modulus to 0.1 MPa or more, it is possible to apply an appropriate stress to the unit cells and to fix the unit cells reliably. From the above viewpoints, the compressive elastic modulus is preferably 0.2 MPa or more, more preferably 0.5 MPa or more. On the other hand, the upper limit is preferably 20 MPa or less from the viewpoint that it is possible to extend the life of the cell because it can absorb the stress caused by swelling during charging and discharging and further expansion during deterioration over time. , is more preferably 15 MPa or less, and even more preferably 10 MPa or less.
The compressive modulus (23° C.) is generally measured according to JIS K7181, but in the present invention, it is simply assumed that the thickness of the partition member is about 95% to 50% when no pressure is applied. It is a value obtained by measuring the pressure and the thickness of the partition member when a pressure is applied such that the thickness is not applied, and calculating and evaluating the ratio to the thickness when no pressure is applied.
The partition member can be used as it is to separate cells or separate cells from other members. A tape may be applied to the surface, or a piece of resin or the like may be attached to the surface.

[Cell]
The cell is preferably a lithium ion secondary battery including, for example, a positive electrode and a negative electrode capable of intercalating and deintercalating lithium ions, and an electrolyte. In addition to lithium ion secondary batteries, secondary batteries such as lithium ion all-solid batteries, nickel-hydrogen batteries, nickel-cadmium batteries, and lead-acid batteries can be applied.
Moreover, as for the form of the cell, it can be applied regardless of the form of the battery, such as a rectangular cell, a pouch-shaped cell, a cylindrical cell, or the like.
5 is a plan view showing an example of the cell 200 that constitutes the assembled battery, FIG. 6 is a front view of the cell 200 shown in FIG. 5, and FIG. 7 is a right side view of the cell 200. . The cell 200 is formed in a rectangular parallelepiped shape having a height direction (H), a width direction (W), and a thickness direction (D), and terminals 210 and 220 are provided on the upper surface thereof.

The assembled battery according to the present embodiment as described above is used in, for example, an electric vehicle (EV), a hybrid electric vehicle (HEV), and a plug-in hybrid electric vehicle (PHEV). , electric heavy machinery, electric motorcycles, electric assist bicycles, ships, aircraft, trains, uninterruptible power supply (UPS, Uninterruptible Power Supply), household power storage systems, and renewable energy sources such as wind power, solar power, tidal power, and geothermal heat. It is applied to battery packs installed in power system stabilization storage battery systems, etc. However, the assembled battery can also be used as a power source that supplies power to devices other than the above-described EV.

(Evaluation method)
Evaluation method 1 (thermal insulation)
The insulating properties of the partition members produced in Examples and Comparative Examples were evaluated using a test apparatus as shown in FIG. Specifically, the partition member 1 was placed on a brass metal plate 403 with a thickness of 1 mm, and a brass metal block 402 with a thickness of 5 mm was set on the partition member 1 . Metal plate 403 , partition member 1 , and metal block 402 were covered with heat insulating material 401 except for the lower portion of metal plate 403 . Nitrogen gas at 300° C. heated by two tube heaters 404 was blown from below onto the metal plate 403 , and the temperature of the metal block positioned above the partition member 1 was measured.

Evaluation method 2 (compressive modulus)
The thickness of the partition member produced in each of Examples and Comparative Examples was actually evaluated when a pressure of 1.4 MPa was applied in Examples 1 to 4 and a pressure of 1.5 MPa was applied in Comparative Example 1. The compression modulus was evaluated by calculating from the ratio to the thickness when no pressure was applied.

Example 1
Using a polypropylene sheet having a thickness of 0.3 mm, a tray-like member as shown in FIG. 1 was produced by vacuum forming. The shape of the lowest part of the recess was a square of 7.79 mm×7.79 mm, and the depth was 2 mm. The area ratio of the concave portion when viewed from above was 61% of the total area. The tray-shaped member was 60 mm long and 120 mm wide.
Next, as shown in FIG. 2, the concave portion of the tray-shaped member 2 is filled with a calcium silicate paste (heat-resistant particle paste 3), and an aluminum laminate film (polyethylene terephthalate with a thickness of 0.012 mm as a resin layer (outer side ), 0.015 mm thick nylon (inner side), and 0.06 mm thick polypropylene (innermost side)), and sealed (sealed) using a vacuum degassing sealer to obtain a partition member. The thickness of the entire partition member was 2.5 mm.
The prepared partition member was evaluated by the evaluation method described above. Table 1 shows the evaluation results. The calcium silicate paste was prepared as follows.
(calcium silicate paste)
0.87 g of calcium silicate was added to 9.13 g of water and kneaded with a stirring bar at room temperature for 5 minutes to obtain a calcium silicate paste.

Example 2
A partition member was obtained in the same manner as in Example 1, except that a zeolite paste prepared by using 4.2 g of zeolite 13X and 5.3 g of water was used instead of calcium silicate. Table 1 shows the results of evaluation in the same manner as in Example 1.

Example 3
A partition member was obtained in the same manner as in Example 1, except that a zeolite paste prepared by using 5.0 g of zeolite 4A and 5.3 g of water was used instead of calcium silicate. Table 1 shows the results of evaluation in the same manner as in Example 1.

Example 4
A partition member was obtained in the same manner as in Example 1, except that calcium silicate powder was used in place of the calcium silicate paste. Table 1 shows the results of evaluation in the same manner as in Example 1.

Comparative example 1
A porous sheet (calcium silicate paper, length 118 mm, width 61 mm, thickness 1.8 mm) as a heat insulating material, aluminum laminate film (polyethylene terephthalate (outside) with a thickness of 0.012 mm as a resin layer, thickness 0 015 mm nylon (inner), including 0.06 mm thick polypropylene (innermost). After 5.0 g of water was added to the heat insulating material placed in the exterior body, the interior was sealed (sealed) using a vacuum degassing sealer to obtain a partition member. The thickness of the entire partition member was 2.0 mm. Table 1 shows the results of evaluation in the same manner as in Example 1.

As can be seen from Table 1, in comparison with Comparative Example 1, Examples 1 to 3 exhibited a slower temperature rise and a higher compression modulus. Further, from the results of Example 4, it can be seen that even in the case of using only the powder without using the liquid, the same elastic modulus as in Comparative Example 1 using water is exhibited. Thus, it was confirmed that the partition member of the present invention exhibited an effect equivalent to that of the conventional partition member (Comparative Example 1) without using liquid.

The partition member of the present invention normally exhibits good elasticity and pressure resistance, and can efficiently transfer heat generated from adjacent unit cells to adjacent unit cells. In addition, in the event of an abnormality in which adjacent unit cells are damaged and the damage may spread to the entire assembled battery in a chain reaction, it is possible to prevent a chain of damage between the unit cells.
Therefore, the assembled battery using the partition member of the present invention is promising as a secondary battery with high safety, for example, as a power source for vehicles even though it has a high energy density.

1 partition member 2 tray-shaped member (compressibility control layer)
3 Heat-resistant particle paste (heat transfer control layer)
4 Exterior body 100 Battery pack 200 Single cell 210 Terminal 220 Terminal 300 Case 400 Thermal insulation evaluation tester 401 Heat insulating material 402 Metal block 403 Metal plate 404 Tube heater t Depth of concave portion of tray-shaped member D Thickness direction P Surface direction H Height direction W Width direction TC1, TC2, TC3 Thermocouple

Claims (10)

A partition member having a thickness direction and a surface direction orthogonal to the thickness direction, and partitioning between the cells or between the cells and members other than the cells in the thickness direction, the partition member comprising a heat transfer control layer and a compressibility control layer. A partition member that includes layers and an outer body that accommodates them. 2. The compressibility control layer is a tray-shaped member having a plurality of recesses, and the heat transfer control layer is composed of a paste containing at least one selected from the group consisting of heat-resistant particles and heat-resistant fibers and a liquid. The partition member according to . 3. The partitioning member according to claim 2, wherein the concave portion of the tray-shaped member is filled with the paste. 4. The partition member according to claim 2, wherein said liquid is water. 2. The partition member according to claim 1, wherein said compressibility control layer is a tray-shaped member having a plurality of recesses, and said heat transfer control layer is composed of at least one selected from the group consisting of heat-resistant particles and heat-resistant fibers. The partition member according to any one of claims 2 to 5, wherein the tray-shaped member is made of thermoplastic resin. 7. The partition member according to claim 6, wherein said thermoplastic resin is an olefin resin. 8. The partition member according to claim 7, wherein said olefinic resin is polypropylene. The partition member according to any one of claims 2 to 8, wherein the heat-resistant particles are at least one selected from the group consisting of calcium silicate and zeolite. An assembled battery comprising the partition member according to any one of claims 1 to 9 and a plurality of cells.

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