Spacer and battery pack

Abstract

This spacer has a thickness direction and a surface direction orthogonal to the thickness direction, and includes an exterior material and an encapsulating material for partitioning, in the thickness direction, single cells or a single cell and a member other than the single cell. The encapsulating material is provided with an electric insulation part including a first inorganic layer, a first intermediate layer, and a second inorganic layer stacked in the thickness direction. The first intermediate layer is a resin layer. The first intermediate layer is in contact with the first inorganic layer and the second inorganic layer. The encapsulating material further includes a liquid.

Description

Spacers and battery packs

[0001] This invention relates to a battery pack and a spacer that is housed inside the battery pack and separates the battery components.

[0002] In recent years, secondary batteries, which are increasingly used as power sources for vehicles and other devices, are being studied for their high energy density in order to improve flexibility when installing them in the limited space of vehicles and to extend the driving range on a single charge. On the other hand, the safety of secondary batteries tends to be inversely related to energy density, and the higher the energy density of a secondary battery, the lower its safety tends to be. For example, in secondary batteries installed in electric vehicles with a driving range of several hundred kilometers, if the secondary battery is damaged due to overcharging or an internal short circuit, the surface temperature of the battery can exceed several hundred degrees Celsius and may even reach nearly 1000 degrees Celsius.

[0003] Secondary batteries used as power sources for vehicles and other devices are generally used as battery packs consisting of multiple individual cells. If one of the individual cells in a battery pack is damaged and reaches the temperature range described above, the heat generated can damage adjacent cells, potentially causing a chain reaction of damage to the entire battery pack. To prevent such a chain reaction of damage between individual cells, various techniques have been proposed, such as placing spacers between cells to cool the damaged cell, or using porous materials as spacers between cells.

[0004] For example, a spacer has been proposed that uses a metal layer with high barrier properties as an outer material to hold the contained liquid (see Patent Document 1).

[0005] International Publication No. 2020 / 203646

[0006] Patent Document 1 discloses a spacer that can suppress the reduction of liquid contained in the spacer even after long-term use, and can prevent a decrease in heat transfer performance under normal conditions. In the event of an abnormality such as a runaway battery, the spacer's thermal conductivity decreases as the liquid is discharged to the outside, and the spacer acts as an insulator, suppressing the temperature rise of adjacent cells. This mechanism can extend the heat transfer time to the entire battery. However, there was room for improvement in the heat transfer time with existing spacers. The present invention provides a highly safe spacer and a battery pack incorporating the same that further extends the heat transfer time and can suppress a rapid temperature rise in the event of an abnormality. In other words, the object of the present invention is to provide a highly safe spacer and a battery pack incorporating the same.

[0007] As a result of diligent research to solve the aforementioned problems, the inventors of the present invention have found that the above problems can be solved by having a spacer composed of an exterior material and an internal material, wherein the internal material is composed of two inorganic layers and an intermediate layer, and have completed the present invention.

[0008] In other words, the present invention includes the following embodiments: [A1] A spacer having a thickness direction and a surface direction perpendicular thereto, which partitions between single cells or between a single cell and a member other than the single cell in the thickness direction, wherein the spacer includes an insulating portion comprising a first inorganic layer, a first intermediate layer, and a second inorganic layer laminated in the thickness direction, the first intermediate layer being a resin layer, the first intermediate layer being in contact with the first inorganic layer and the second inorganic layer, the spacer further containing a liquid, the spacer including a sealing portion, the spacer and the first inorganic layer overlapping, and the sealing portion being excluded A spacer having the area S1 of a first region, the area S2 of a second region in which the exterior material and the first inorganic layer do not overlap and the sealing portion is excluded, the area S3 of a third region in which the exterior material and the first intermediate layer overlap, the area S4 of the spacer, the area S5 of the sealing portion, the area S11 of a first region in which the exterior material and the insulating portion overlap and the sealing portion is excluded, the area S12 of a second region in which the exterior material and the insulating portion do not overlap and the sealing portion is excluded, the thickness D2 of the insulating portion, the volume V1 of the liquid, and the volume V2 of the inorganic layer. [A2] The spacer according to [A1], wherein the spacer includes a sealing portion, and in a plan view from the thickness direction of the spacer, the exterior material and the insulating portion overlap, and the area S11 of the first region excluding the sealing portion, the area S12 of the second region excluding the sealing portion where the exterior material and the insulating portion do not overlap, the thickness D2 of the insulating portion, and the volume V1 of the liquid satisfy the following formula 1. Formula 1: 0.05 ≤ V1 / ((S11 + S12) × D2) [A3] The spacer according to [A1] or [A2], wherein the burst pressure P of the spacer is 9.0 to 30.0 MPa. [A4] The spacer according to any one of [A1] to [A3], wherein the burst pressure P of the spacer is 11.0 to 30.0 MPa. [A5] The ratio of the burst pressure P of the spacer to the area S12 of the second region, P / S12, is 0.60 to 2.0 MPa / mm². ２ The spacer described in any one of [A1] to [A4]. [A6] The ratio of the burst pressure P of the spacer to the area S12 of the second region P / S12 is 0.70 to 2.0 MPa / mm ２The spacer according to any one of [A1] to [A5] above. [A7] The spacer according to any one of [A1] to [A6] above, wherein the area S11 of the first region, the thickness D2 of the insulating portion, and the volume V2 of the inorganic layer satisfy the following formula 2. Formula 2: 0.01 ≤ 1 - {V2 / (S11 × D2)} ≤ 0.9 [A8] The spacer according to any one of [A1] to [A7] above, wherein the spacer includes a sealing portion, the exterior material and the first inorganic layer overlap, the area S1 of the first region excluding the sealing portion, the area S2 of the second region excluding the sealing portion where the exterior material and the first inorganic layer do not overlap, and the area S3 of the third region where the exterior material and the first intermediate layer overlap satisfy the following formula 3. Equation 3: S1 + S2 ≥ S3 [A9] A spacer according to any one of [A1] to [A8] above, wherein the area S1 of the first region and the area S2 of the second region satisfy the following Equation 4: Equation 4: 0.60 ≤ S1 / (S1 + S2) ≤ 1.0 [A10] A spacer according to any one of [A1] to [A9] above, wherein the area S1 of the first region and the area S2 of the second region satisfy 0.84 ≤ S1 / (S1 + S2) ≤ 0.95. [A11] A spacer according to any one of [A1] to [A10] above, wherein in a plan view from the thickness direction of the spacer, the ratio S1 / S4 of the area S1 of the first region to the area S4 of the spacer satisfies 0.60 to 1.0. [A12] A spacer according to any one of [A1] to [A11], wherein, in a plan view from the thickness direction of the spacer, the ratio S1 / S4 of the area S1 of the first region to the area S4 of the spacer is 0.65 to 0.95. [A13] A spacer according to any one of [A1] to [A12], wherein the first intermediate layer does not come into contact with the exterior material. [A14] The exterior material includes a sealing portion, and the ratio P / S5 of the bursting pressure P of the spacer to the area S5 of the sealing portion in a plan view from the thickness direction is 0.30 to 2.0 MPa / mm². ２ The spacer described in any one of the above [A1] to [A13]. [A15] The exterior material includes a sealing portion, and the ratio of the burst pressure P of the spacer to the area S5 of the sealing portion in a plan view from the thickness direction, P / S5, is 0.50 to 2.0 MPa / mm ２A spacer according to any one of [A1] to [A14] above. [A16] A spacer according to any one of [A1] to [A15] above, wherein when the average surface temperature of the spacer is 80°C or higher, the liquid is discharged to the outside of the spacer. [A17] A spacer according to any one of [A1] to [A16] above, wherein a mixed layer of an inorganic layer and a resin layer is included between the first inorganic layer and the first intermediate layer. [A18] A spacer according to any one of [A1] to [A17] above, wherein the exterior material includes a sealant resin layer and a metal layer, and the difference between the melting point of the resin included in the first intermediate layer and the melting point of the resin included in the sealant resin layer of the exterior material is within 60°C. [A19] A spacer according to any one of [A1] to [A18] above, wherein the exterior material includes a sealant resin layer and a metal layer, and the difference between the melting point of the resin included in the first intermediate layer and the melting point of the resin included in the sealant resin layer of the exterior material is within 20°C. [A20] A spacer according to any one of [A1] to [A19] above, wherein the thickness of the first intermediate layer is 0.01 to 0.1 mm. [A21] A spacer according to any one of [A1] to [A20] above, wherein the thickness of the first intermediate layer is 0.1 to 3 mm. [A22] A battery pack comprising the spacer according to any one of [A1] to [A21] above and a single cell.

[0009] [B1] A spacer comprising an outer material and an inner material, wherein the outer material includes a sealing portion, the inner material includes an insulating portion comprising a first inorganic layer and a liquid, and in a plan view from the thickness direction of the spacer, the area S1 of a first region where the outer material and the first inorganic layer overlap and excluding the sealing portion, the area S2 of a second region where the outer material and the first inorganic layer do not overlap and excluding the sealing portion, the area S11 of a first region where the outer material and the insulating portion overlap and excluding the sealing portion, the area S12 of a second region where the outer material and the insulating portion do not overlap and excluding the sealing portion, the thickness D2 of the insulating portion, and the volume V1 of the liquid satisfy the following formula 1, and the burst pressure P of the spacer is 11.0 MPa or more. Formula 1: 0.05 ≤ V1 / ((S11 + S12) × D2) [B2] A spacer comprising an outer material and an inner material, wherein the outer material includes a sealing portion, and the inner material includes an insulating portion comprising a first inorganic layer and a liquid, and in a plan view from the thickness direction of the spacer, the area S1 of a first region where the outer material and the first inorganic layer overlap and excluding the sealing portion, the area S2 of a second region where the outer material and the first inorganic layer do not overlap and excluding the sealing portion, the area S11 of a first region where the outer material and the insulating portion overlap and excluding the sealing portion, the area S12 of a second region where the outer material and the insulating portion do not overlap and excluding the sealing portion, the thickness D2 of the insulating portion, the volume V1 of the liquid, and the volume V2 of the inorganic layer satisfy the following formulas 1 and 2. Equation 1: 0.05 ≤ V1 / ((S11 + S12) × D2) Equation 2: 0.01 ≤ 1 - {V2 / (S11 × D2)} ≤ 0.9 [B3] A spacer comprising an outer material and an inner material, wherein the outer material includes a sealing portion, and the inner material includes an insulating portion comprising a first inorganic layer, a first intermediate layer, and a liquid, and in a plan view from the thickness direction of the spacer, the area S1 of a first region where the outer material and the first inorganic layer overlap and excluding the sealing portion, the area S2 of a second region where the outer material and the first inorganic layer do not overlap and excluding the sealing portion, and the area S3 of a third region where the outer material and the first intermediate layer overlap satisfy the following Equation 3.Equation 3: S1 + S2 ≥ S3 [B4] A spacer comprising an outer material and an inner material, wherein the inner material comprises a first inorganic layer, a first intermediate layer, and a second inorganic layer laminated in the thickness direction, and the first inorganic layer and the second inorganic layer contain a liquid. [B5] The spacer according to [4] above, wherein the outer material includes a sealing portion, and in a plan view from the thickness direction of the spacer, the outer material and the first inorganic layer and the second inorganic layer overlap, and there is an area S1' of a fourth region excluding the sealing portion, the outer material and the first inorganic layer and the second inorganic layer do not overlap, and there is an area S2' of a fifth region excluding the sealing portion, and the outer material and the first intermediate layer overlap, and the areas of the third to fifth regions satisfy S1' + S2' ≥ S3. [B6] The spacer according to [5], wherein the relationship between the area S1' of the fourth region and the area S3 of the third region satisfies 0.9S1' ≤ S3 ≤ 1.1S1'. [B7] The spacer according to any one of [1] to [3], wherein the insulating portion further includes a first intermediate layer. [B8] The spacer according to any one of [1] to [3] or [7], wherein S1 and S2 satisfy the following formula 4: Formula 4: 0.60 ≤ S1 / (S1 + S2) [B9] The spacer according to any one of [1] to [8], wherein the liquid is discharged to the outside of the spacer when the average surface temperature of the spacer is 80°C or higher. [B10] The spacer according to any one of [4] to [9], wherein the first intermediate layer includes at least one selected from a metal layer, a resin layer, and a glass layer. [B11] The spacer according to any one of [4] to

[10] above, wherein the first intermediate layer is a resin layer, and a mixed layer of the inorganic layer and the resin layer is included between the first inorganic layer and the first intermediate layer. [B12] The spacer according to any one of [4] to

[11] above, wherein the first intermediate layer is a resin layer, the exterior material includes a sealant resin layer and a metal layer, and the difference between the melting point of the resin included in the first intermediate layer and the melting point of the resin included in the sealant resin layer of the exterior material is 20°C or less. [B13] The spacer according to any one of [4] to

[12] above, wherein the first intermediate layer includes a resin with a melting point of 300°C or less. [B14] The spacer according to any one of [4] to

[13] above, wherein the thickness of the first intermediate layer is 0.1 to 3 mm.[B15] The spacer according to [7], wherein the encapsulating material further comprises a second inorganic layer. [B16] The spacer according to any one of [4] to

[15] , wherein at least one of the first inorganic layer and the second inorganic layer is bonded to the first intermediate layer. [B17] The spacer according to any one of [4] to

[16] , wherein the encapsulating material further comprises a second intermediate layer and a third inorganic layer laminated in the thickness direction. [B18] A battery pack comprising the spacer and single cell according to any one of [1] to

[17] .

[0010] According to the present invention, it is possible to provide a highly safe spacer that can suppress a rapid temperature rise in the event of an abnormality such as a runaway battery, and a battery pack incorporating the same.

[0011] Figure 1 is a front view of an example of the configuration of a spacer according to one embodiment of the present invention. Figure 2 is a cross-sectional view of the spacer shown in Figure 1 when cut along line A-A. Figure 3 shows an example of a single cell. Figure 4 is a front view of the single cell shown in Figure 3. Figure 5 is a side view of the single cell shown in Figure 3. Figure 6 is a top view showing an example of a battery pack. Figure 7 is a schematic side view of the battery pack shown in Figure 6 with the front side plate removed. Figure 8 is a schematic diagram showing an example of a test apparatus for evaluating the thermal insulation performance of the spacer of the present invention.

[0012] The present invention will now be described. The description of the embodiments shown in the drawings below is illustrative, and the present invention is not limited to the configurations shown in the drawings. In this specification, when "X to Y" or "X to Y" (where X and Y are any numbers) is used, unless otherwise specified, it includes the meaning of "X or more and Y or less," as well as "preferably greater than X" and "preferably less than Y." Furthermore, when "X or more" (where X is any number) is used, unless otherwise specified, it includes the meaning of "preferably greater than X," and when "Y or less" (where Y is any number) is used, unless otherwise specified, it includes the meaning of "preferably less than Y." Even when the lower limit X and upper limit Y are described independently for the same parameter, this discloses any combination of lower limit X and upper limit Y. Also, when disclosing independent embodiments of the present invention, these embodiments can be combined in any way.

[0013] <Spacer> Figures 1 and 2 show examples of the configuration of the spacer of the present invention. Figure 1 shows a front view (plan view from the thickness direction) of the spacer 1. Figure 2 shows a cross-section of the right side when the spacer 1 shown in Figure 1 is cut along the line A-A.

[0014] In the examples shown in Figures 1 and 2, the spacer 1 has an overall shape that is flat or sheet-like, with a height direction (H), a width direction (W), and a thickness direction (D). The spacer 1 has a thickness direction (D) and a surface direction (P) perpendicular to the thickness direction (D). The surface direction (P) includes the height direction (H) and width direction (W) described above, as well as a plurality of oblique directions between the height direction (H) and width direction (W).

[0015] The spacer 1 includes an internal material 110, and preferably the internal material 110 is sealed inside the outer material 120 to form a plate or sheet. The thickness of the spacer 1 is preferably 0.80 to 20 mm, and more preferably 1.0 to 10 mm.

[0016] The inner material 110 of the spacer 1 may or may not be sealed by the outer material 120. The spacer 1 may also have a laminated structure in which the outer material is positioned on the outside relative to the inner material. In the example shown in Figure 1, the outer material 120 is provided with a sealing portion 120a that seals its peripheral edge, and the inner material 110 is housed in an internal space 111 formed in the outer material 120 by the sealing portion 120a. The internal space 111 is a space sealed by the outer material and indicates a region in which liquid can move. In the example shown in Figure 1, a gap 120b is provided between the sealing portion 120a and the inner material 110 in the internal space 111. However, the gap 120b is not necessarily required. The gap 120b may be such that the inner surfaces of the outer material 120 are in contact with each other when there is no fluid (gas and liquid) present. In this invention, the volume of the internal space 111 is defined as the product of the area of ​​the internal space 111 in a plan view from the thickness direction of the spacer 1 and the thickness of the internal material 110. Furthermore, the placement of the internal material 110 does not necessarily have to be in the center of the internal space, nor does it necessarily have to be parallel to the exterior material 120.

[0017] The spacer 1 comprises an insulating portion in which the encapsulating material includes a first inorganic layer and a first intermediate layer stacked in the thickness direction, and the encapsulating material further contains a liquid.

[0018] Preferably, in a plan view from the thickness direction, the spacer 1 satisfies the following equation 1: 0.05 ≤ V1 / ((S11 + S12) × D2)

[0019] The lower limit of V1 / ((S11+S12)×D2) in the above formula 1 is 0.05, but is preferably 0.10, more preferably 0.15, even more preferably 0.20, and even more preferably 0.25. The upper limit is preferably 1.0, more preferably 0.8, even more preferably 0.6, and even more preferably 0.4.

[0020] Preferably, in a plan view from the thickness direction, the spacer 1 satisfies the following equation 2: 0.01 ≤ 1 - {V2 / (S11 × D2)} ≤ 0.9

[0021] The lower limit of 1 - {V2 / (S11×D2)} in formula 2 above is 0.01, but is preferably 0.1, more preferably 0.2, and even more preferably 0.3. The upper limit is 0.9, but is preferably 0.8.

[0022] Preferably, in a plan view from the thickness direction, the spacer 1 satisfies the following equation 3: the area S1 of a first region where the exterior material 120 and the first inorganic layer overlap, excluding the sealing portion 120a; the area S2 of a second region where the exterior material 120 and the first inorganic layer do not overlap, excluding the sealing portion 120a; and the area S3 of a third region where the exterior material 120 and the first intermediate layer overlap. Equation 3: S1 + S2 ≥ S3

[0023] In a plan view from the thickness direction, it is preferable that the area S1 of the first region where the exterior material 120 and the first inorganic layer overlap, excluding the sealing portion 120a, and the area S2 of the second region where the exterior material 120 and the first inorganic layer do not overlap, excluding the sealing portion 120a, satisfy the following formula 4. Formula 4: 0.60 ≤ S1 / (S1 + S2)

[0024] The lower limit of S1 / (S1+S2) in the above formula 4 is 0.60, but is preferably 0.70, more preferably 0.80, even more preferably 0.82, and most preferably 0.84. The upper limit is preferably 1.00, more preferably 0.95, and even more preferably 0.90.

[0025] In a plan view of the spacer from the thickness direction, the lower limit of the ratio S1 / S4 of the area of ​​the first region to the area S4 of the spacer is preferably 0.60, more preferably 0.65, more preferably 0.70, and more preferably 0.75, from the viewpoint of improving thermal insulation in abnormal situations. The upper limit is preferably 1.0, more preferably 0.95, and more preferably 0.90.

[0026] One embodiment of the spacer 1 is a spacer including an outer material and an inner material, wherein the outer material includes a sealing portion, and the inner material includes an insulating portion containing a first inorganic layer and a liquid, and in a plan view from the thickness direction of the spacer, the area S11 of the first region where the outer material and the insulating portion overlap and excluding the sealing portion, the area S12 of the second region where the outer material and the insulating portion do not overlap and excluding the sealing portion, the thickness D2 of the insulating portion, and the volume V1 of the liquid satisfy the following formula 1, and the burst pressure P of the spacer is 11.0 MPa or more. Formula 1: 0.05 ≤ V1 / ((S11 + S12) × D2)

[0027] The lower limit of the burst pressure P of the above-mentioned spacer is preferably 9.0 MPa, more preferably 10.0 MPa, more preferably 11.0 MPa, more preferably 11.5 MPa, more preferably 12.0 MPa, more preferably 12.5 MPa, more preferably 13.0 MPa, more preferably 13.5 MPa, more preferably 14.0 MPa, more preferably 14.5 MPa, more preferably 15.0 MPa, more preferably 15.5 MPa, and more preferably 16.0 MPa. The upper limit is preferably 30.0 MPa, more preferably 25.0 MPa, and even more preferably 20.0 MPa. The burst pressure P of the spacer can be calculated by placing a metal plate on the spacer, applying a load using a high-pressure jack, and dividing the load at the time the spacer bursts by the area of ​​the internal space within the spacer.

[0028] The lower limit of the ratio P / S12 of the burst pressure P of the spacer to the area S12 of the second region is preferably 0.60, preferably 0.65, more preferably 0.70, and more preferably 0.75, from the viewpoint of extending the plateau time. The upper limit is preferably 2.0, more preferably 1.9, and more preferably 1.80.

[0029] The lower limit of the ratio P / S5 of the burst pressure of the spacer to the area S5 of the sealing portion in a plan view from the thickness direction is preferably 0.30, more preferably 0.40, from the viewpoint of extending the plateau time. The upper limit is preferably 2.0, more preferably 1.8.

[0030] Another embodiment of spacer 1 is a spacer including an outer material and an inner material, wherein the outer material includes a sealing portion, and the inner material includes an insulating portion containing a first inorganic layer and a liquid, and in a plan view from the thickness direction of the spacer, the area S11 of a first region where the outer material and the insulating portion overlap and excluding the sealing portion, the area S12 of a second region where the outer material and the insulating portion do not overlap and excluding the sealing portion, the thickness D2 of the insulating portion, the volume V1 of the liquid, and the volume V2 of the inorganic layer satisfy the following equations 1 and 2. Equation 1: 0.05 ≤ V1 / ((S11 + S12) × D2) Equation 2: 0.01 ≤ 1 - {V2 / (S11 × D2)} ≤ 0.9

[0031] Another embodiment of spacer 1 is a spacer including an outer material and an inner material, wherein the outer material includes a sealing portion, and the inner material includes an insulating portion including a first inorganic layer, a first intermediate layer, and a liquid, and in a plan view from the thickness direction of the spacer, the area S1 of a first region where the outer material and the first inorganic layer overlap and excluding the sealing portion, the area S2 of a second region where the outer material and the first inorganic layer do not overlap and excluding the sealing portion, and the area S3 of a third region where the outer material and the first intermediate layer overlap satisfy the following equation 3. Equation 3: S1 + S2 ≥ S3

[0032] In yet another embodiment of the spacer 1, the spacer includes an outer material and an inner material, wherein the inner material includes a first inorganic layer, a first intermediate layer, and a second inorganic layer laminated in the thickness direction, and the first and second inorganic layers contain a liquid. Preferably, the outer material includes a sealing portion, and in a plan view from the thickness direction (D) of the spacer, the outer material and the first and second inorganic layers overlap, forming a fourth region S1' excluding the sealing portion, a fifth region S2' where the outer material and the first and second inorganic layers do not overlap, forming a fifth region S2' excluding the sealing portion, and the outer material and the first intermediate layer overlap, forming a third region S3 (not shown), where the areas of the third to fifth regions satisfy S1' + S2' ≥ S3. It is also preferable that 0.9S1' ≤ S3 ≤ 1.1S1'. By satisfying the above relationship in the areas of the third to fifth regions, the plateau time described later can be lengthened.

[0033] The spacer 1 preferably has an encapsulating material containing a second inorganic layer. Further, when the encapsulating material contains both the first inorganic layer and the second inorganic layer, it is preferable that the area of the first inorganic layer and the area of the second inorganic layer are equal in a plan view from the thickness direction. In this case, the area S1 and the area S1' are equal, and the area S2 and the area S2' are equal.

[0034] The spacer 1 is used to partition between single cells constituting a battery pack or between a single cell and a member other than a single cell in its thickness direction (D), contacts a single cell in the thickness direction (D) shown in FIG. 2, has a heat transfer property during normal use, and has a function of exhibiting heat insulation property during an abnormal situation such as a battery runaway. As the temperature of the spacer 1 contacting the single cell where an abnormality has occurred rises, the liquid is discharged to the outside of the spacer. The above function can occur when the substance dominant for the thermal conductivity of the spacer 1 changes from a liquid to a material constituting an inorganic layer.

[0035] Specifically, when the surface average temperature of the spacer is 80° C. or higher, it is preferable that the liquid is discharged to the outside of the spacer. Further, while the liquid is discharged to the outside of the spacer, since external heat is used for the phase change of the liquid or the like, the temperature rise of adjacent single cells can be suppressed.

[0036] Here, the time from when the surface average temperature of the spacer reaches the boiling point of the liquid until it starts to rise again is referred to as the plateau time. A spacer with a long plateau time can be said to be a highly safe spacer that can suppress rapid temperature rise. Furthermore, a spacer with high heat insulation after the phase change can enhance safety more because the temperature rise after the plateau time becomes gentle. The plateau time corresponds to the total of the time until the outer packaging material is opened and the time when the liquid is discharged outside the spacer. Therefore, from the perspective of increasing the time until the outer packaging material is opened, the sealing strength of the spacer can be increased, the liquid content can be decreased, the contrast space of the liquid can be provided in the plane direction or the thickness direction, etc. to increase the rupture pressure. Also, from the perspective of increasing the time when the liquid is discharged outside the spacer, a liquid with a low vapor pressure can be used for the inner packaging material of the spacer, or an intermediate layer can be inserted to inhibit the discharge of the liquid. Furthermore, to increase the heat insulation of the spacer after the phase change, an inorganic layer with a low thermal conductivity can be used, or the area ratio of the inorganic layer in the plane view in the thickness direction occupying the entire spacer can be increased.

[0037] Note that the "liquid" in this specification is not particularly limited as long as it is a material that exhibits the function of the above spacer, and means a substance that is in a flowing state at 100°C and 1 atm, and preferably this flowing state is a liquid state. As the liquid, for example, substances such as gels that are not in a flowing state at 25°C but are in a flowing state at 100°C and 1 atm can also be included, and any liquid can be used. However, from the perspective of safety, the liquid preferably contains water.

[0038] The inorganic layer preferably includes a porous body, and as the porous body, it is more preferable to include fibrous inorganic substances or powdery inorganic substances. The inorganic layer may be layers of different materials or layers of the same material. In the present invention, the "fibrous inorganic substance" means an inorganic substance having a shape whose major axis is 100 times or more the minor axis, and the "powdery inorganic substance" means an inorganic substance having a shape whose major axis is less than 100 times the minor axis. In particular, in the case of being fibrous, the "major axis" means the fiber length, and the "minor axis" means the diameter of the cross-section perpendicular to the major axis direction.

[0039] The fibrous inorganic material is preferably at least one selected from the group consisting of, for example, paper, cotton sheets, polyimide fibers, aramid fibers, polytetrafluoroethylene (PTFE) fibers, glass fibers, rock wool, ceramic fibers, and biosoluble inorganic fibers, and among these, it is more preferably at least one selected from glass fibers, rock wool, ceramic fibers, and biosoluble inorganic fibers. The ceramic fiber is mainly composed of silica and alumina (silica:alumina = 40:60 to 0:100), and specifically, silica-alumina fibers, mullite fibers, and alumina fibers can be used.

[0040] The powdered inorganic material is preferably at least one selected from the group consisting of silica particles, alumina particles, calcium silicate, clay minerals, vermiculite, mica, cement, perlite, fumed silica, and aerogel, and more preferably at least one selected from silica particles, alumina particles, calcium silicate, and vermiculite. Among the types of calcium silicate, xonotlite, tobermorite, wollastonite, and gyrolite are preferred, with gyrolite being particularly preferred. Gyrolite, which has a petal-like structure, maintains its porous structure even when compressed and deformed, and therefore has excellent liquid retention properties. The clay minerals are mainly magnesium silicate (including talc and sepiolite), montmorillonite, and kaolinite.

[0041] As a porous body containing fibrous inorganic material and powdered inorganic material, one that satisfies a predetermined density can be selected and used from known types. For example, one can be selected and used from those described in Japanese Patent Application Publication No. 2003-202099.

[0042] Furthermore, the thermal conductivity of the porous material described above is preferably less than 0.20 [W / (m·K)] for the purpose of blocking heat transfer in the event of an abnormality between cells. It is also preferably less than 0.15 [W / (m·K)], and more preferably less than 0.10 [W / (m·K)].

[0043] The first intermediate layer in the encapsulating material is preferably in contact with at least one of the first inorganic layer and the second inorganic layer, which are laminated in the thickness direction, and more preferably bonded to them. Furthermore, the first intermediate layer in the encapsulating material is preferably in contact with both the first inorganic layer and the second inorganic layer, which are laminated in the thickness direction, and more preferably bonded to them. Bonding the inorganic layer and the intermediate layer reduces the number of steps required in the manufacturing of the encapsulating material, and also allows for efficient matching of the area of ​​the inorganic layer and the intermediate layer in the thickness direction when used as an encapsulating material.

[0044] The encapsulating material preferably includes a second intermediate layer and a third inorganic layer laminated in the thickness direction, in which case the second intermediate layer is laminated between the third inorganic layer and the first or second inorganic layer. Furthermore, the second intermediate layer is preferably bonded to at least one of the third inorganic layer or the first or second inorganic layer, and more preferably bonded to both the third inorganic layer and the first or second inorganic layer. By bonding the second intermediate layer to the inorganic layer, the time it takes for the liquid contained in the inorganic layer to be discharged to the outside of the spacer can be delayed, and the temperature rise in abnormal situations can be further suppressed.

[0045] The first intermediate layer preferably includes at least one selected from a metal layer, a resin layer, and a glass layer, and more preferably includes a resin layer. If a second intermediate layer is included, the second intermediate layer preferably includes at least one of a metal layer or a resin layer, and more preferably includes a resin layer.

[0046] The resins used in the above resin layer are preferably polyethylene, polypropylene, polystyrene, nylon, acrylic, epoxy resin, polyurethane, polyetherketone, polyetherimide, polyethylene terephthalate, polyphenyl sulfide, polycarbonate, and aramid.

[0047] Preferred metals for the above-mentioned metal layer include aluminum or aluminum alloys, copper or copper alloys, tin or tin alloys, nickel or nickel alloys, stainless steel, lead or lead alloys, bronze, iridium, phosphor bronze, silver or silver alloys, and titanium or titanium alloys.

[0048] In the present invention, when the first intermediate layer is a resin layer, it is preferable to include a mixed layer of the inorganic layer and the resin layer between the first inorganic layer and the first intermediate layer, and it is even more preferable to include a mixed layer of the inorganic layer and the resin layer between the second inorganic layer and the first intermediate layer. When the first intermediate layer is a resin layer, a portion of the resin of the first intermediate layer can melt during lamination and impregnate the inorganic layer, and a mixed layer containing the inorganic layer and the resin layer can be formed on the surface of the inorganic layer. By including this mixed layer in the encapsulating material, the time it takes for the liquid contained in the inorganic layer to be discharged to the outside of the spacer can be delayed, and the temperature rise in abnormal situations can be further suppressed.

[0049] The first intermediate layer preferably contains a resin with a melting point of 300°C or lower, more preferably a resin with a melting point of 200°C or lower, and even more preferably a resin with a melting point of 180°C or lower. Specifically, it preferably contains polyethylene, polypropylene, polystyrene, nylon, acrylic, and polyethylene terephthalate as described above.

[0050] The thickness of the first intermediate layer is preferably 0.01 to 0.1 mm from the viewpoint of forming a buffer in the planar direction. The thickness of the first intermediate layer is preferably 0.1 to 3 mm, and more preferably 0.2 to 2 mm, from the viewpoint of forming a buffer in the thickness direction. If the thickness of the first intermediate layer is within the above range, the handling properties and heat insulation properties will be better.

[0051] The first intermediate layer may or may not be in contact with the exterior material, but from the viewpoint of simplifying the manufacturing process, it is preferable that the first intermediate layer does not come into contact with the exterior material.

[0052] The outer layer of the spacer of the present invention may include multiple layers, but preferably it includes at least a metal layer, and the first layer located outside the metal layer relative to the inner material is a resin layer containing at least one of inorganic particles and a flame retardant. Furthermore, the outer layer may further include a second layer located inside the metal layer, and it is more preferable that the second layer is a sealant resin layer. A reinforcing layer may also be included between the metal layer and the second layer.

[0053] When the first intermediate layer in the aforementioned encapsulating material is a resin layer, the outer material includes a sealant resin layer and a metal layer, and it is preferable that the difference between the melting point of the resin in the first intermediate layer and the melting point of the resin in the sealant resin layer of the outer material is within 60°C, and more preferably within 20°C. If the difference in melting points is within the above range, the time it takes for the liquid contained in the inorganic layer to be discharged to the outside of the spacer can be controlled with precision, and it is easier to suppress temperature rise in abnormal situations. The first layer in the outer material may be a resin layer containing at least one of inorganic particles and a flame retardant, or it may be the same resin as the first intermediate layer or the outer material.

[0054] The thickness of the exterior material is not particularly limited, but considering the thickness of each of the above layers, from the viewpoint of mechanical strength, its thickness is preferably 20 μm or more, more preferably 30 μm or more, and even more preferably 40 μm or more. Furthermore, in order to ensure flexibility, the thickness of the exterior material is preferably 220 μm or less, more preferably 150 μm or less, and even more preferably 110 μm or less. The resin layer (first layer), metal layer, sealant resin layer (second layer), and reinforcing layer will be described below.

[0055] (Resin layer (first layer)) One embodiment of the resin layer includes at least one of inorganic particles or a flame retardant. There are no particular limitations on the resin layer, and examples include polyolefin resins such as homopolymers or copolymers of ethylene, propylene, butene, etc.; amorphous polyolefin resins such as cyclic polyolefins; polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN); polyamide resins such as nylon 6, nylon 66, nylon 12, copolymer nylon; ethylene-vinyl acetate copolymer partial hydrolysate (EVOH), polyimide resins, polyetherimide resins, polysulfone resins, polyethersulfone resins, polyetheretherketone resins, polycarbonate resins, polyvinyl butyral resins, polyarylate resins, fluororesins, acrylic resins, biodegradable resins, etc. Among these, polyamide resins such as nylon 6 and polyester resins such as polyethylene terephthalate are preferred from the viewpoint of providing heat resistance and mechanical strength as an exterior material. The resin layer may consist of a single layer or two or more layers. If there are two or more layers, different resins may be used, or the same resin may be used. If the resin layer is multilayered, all layers of the multilayer structure are included in the definition of the resin layer.

[0056] There are no particular restrictions on the thickness of the resin layer, but from the viewpoint of flexibility, the thickness of the first layer is preferably 10 to 125 μm, and more preferably 10 to 40 μm.

[0057] Inorganic particles may be included in the resin layer (first layer) from the viewpoint of improving insulation properties. Examples of inorganic particles include silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, kaolin, aluminum oxide, titanium oxide, and carbon black. Of these inorganic particles, silica, aluminum oxide, titanium oxide, and carbon black are preferred from the viewpoint of improving insulation properties, and among these, silica, titanium oxide, and carbon black are particularly preferred. One type of inorganic particle may be used alone, or two or more types may be used in combination. Therefore, a combination of suitable particles such as silica, titanium oxide, and carbon black can also be used.

[0058] In addition to the inorganic particles mentioned above, conventionally used particles may be added to the polyester film to improve its slipperiness and prevent scratches during each process, thereby improving its handling properties. These particles are not particularly limited as long as they can impart slipperiness, and specific examples include, in addition to the inorganic particles mentioned above, cross-linked polymers such as cross-linked silicone resin particles, cross-linked acrylic resin particles, cross-linked styrene-acrylic resin particles, and cross-linked polyester particles, as well as organic particles such as calcium oxalate and ion exchange resins. Furthermore, precipitated particles obtained by precipitating and finely dispersing a portion of metal compounds such as catalysts during the polyester manufacturing process can also be used.

[0059] The shape of the particles used in the resin layer (first layer) is not particularly limited; spherical, lumpy, rod-shaped, flattened, etc., may be used. There are also no particular restrictions on their hardness, specific gravity, color, etc. Two or more types of these particles may be used in combination as needed. Here, "particles" include both inorganic particles for improving the insulating properties of the resin layer (first layer) and particles for improving the slipperiness of the resin layer (first layer).

[0060] Furthermore, the average particle size of the particles used in the resin layer (first layer) is preferably 0.05 to 5.0 μm, more preferably 0.10 to 4.5 μm, more preferably 0.20 to 4.5 μm, and among these, 0.40 to 4.5 μm is particularly preferred. By using the above range, the desired insulating properties of the resin layer (first layer) can be ensured. In the case of powder particles, the average particle size can be determined by using a centrifugal sedimentation particle size distribution analyzer (for example, Shimadzu Corporation's "SA-CP3" model) to measure the particle size at 50% of the cumulative volume fraction in the equivalent spherical distribution (d50). The average particle size of the particles in the layer or resin can be determined by observing 10 or more particles with a scanning electron microscope (SEM), measuring the diameter of the particles, and taking the average value. In the case of non-spherical particles, the average of the longest and shortest diameters can be measured as the diameter of each particle.

[0061] When incorporating particles into the resin layer (first layer), it is preferable to provide a surface layer and an intermediate layer, with the particles being incorporated into the surface layer. Furthermore, in the case of a three-layer structure with different designs on the front and back, it is also possible to incorporate particles into at least one of the surface layers.

[0062] The method for adding particles to the resin layer (first layer) is not particularly limited, and conventionally known methods can be employed. For example, the particles can be added at any stage in the production of polyester, but it is preferable to add them after the esterification or transesterification reaction is completed.

[0063] The resin layer (first layer) may include resins other than polyester, as long as the effects of the present invention are not impaired. Other resins include polystyrene resins, polyvinyl chloride resins, polyvinylidene chloride resins, chlorinated polyethylene resins, polycarbonate resins, polyamide resins, polyacetal resins, acrylic resins, ethylene vinyl acetate copolymers, polymethylpentene resins, polyvinyl alcohol resins, cyclic olefin resins, polylactic acid resins, polybutylene succinate resins, polyacrylonitrile resins, polyethylene oxide resins, cellulose resins, polyimide resins, polyurethane resins, polyphenylene sulfide resins, polyphenylene ether resins, polyvinyl acetal resins, polybutadiene resins, polybutene resins, polyamide-imide resins, polyamide-bismaleimide resins, polyetherimide resins, polyetherether ketone resins, polyethersulfone resins, polyketone resins, polysulfone resins, aramid resins, and fluorine resins.

[0064] (Metal layer) Examples of metal layers include aluminum foil, copper foil, tin foil, nickel foil, stainless steel foil, lead foil, tin-lead alloy foil, bronze foil, iridium foil, and phosphor bronze foil. In particular, aluminum foil, copper foil, and nickel foil are preferred in terms of processability and material availability, and aluminum foil is more preferred from the viewpoint of low density and ease of handling.

[0065] While there are no particular restrictions on the thickness of the metal layer as long as it is 5 μm or more, it is preferable that it be 8 μm or more, and more preferably 12 μm or more, from the viewpoint of suppressing the occurrence of pinholes. Furthermore, from the viewpoint of ensuring flexibility, it is preferable that it be 50 μm or less, more preferably 35 μm or less, and even more preferably 20 μm or less.

[0066] (Sealant resin layer (second layer)) Examples of sealant resins include polyolefin resins such as homopolymers or copolymers of ethylene, propylene, butene, etc.; amorphous polyolefin resins such as cyclic polyolefins; polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN); polyvinyl butyral resins; acrylic resins; biodegradable resins, etc. Among these, it is preferable to use at least one selected from polyolefin resins such as high-pressure low-density polyethylene (LDPE), linear low-density polyethylene (LLPDE), and polypropylene resin, in order to obtain the function of releasing the liquid inside the outer casing to the outside of the spacer in the event of abnormal heat generation. Furthermore, it is even more preferable to use unstretched polypropylene resin in order to obtain long-term storage properties within the temperature range normally used as a spacer for a battery pack and in terms of versatility.

[0067] There are no particular restrictions on the thickness of the sealant resin layer, but from the viewpoint of ensuring sealing performance, its thickness is preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more. Furthermore, in order to ensure flexibility, the thickness of the sealant resin layer is preferably 120 μm or less, more preferably 100 μm or less, and even more preferably 80 μm or less.

[0068] (Reinforcement layer) The exterior material may further include a reinforcement layer between the metal layer and the second layer. The reinforcement layer is not particularly limited and can include, for example, polyolefin resins such as homopolymers or copolymers of ethylene, propylene, butene, etc.; amorphous polyolefin resins such as cyclic polyolefins; polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN); polyamide resins such as nylon 6, nylon 66, nylon 12, copolymer nylon; ethylene-vinyl acetate copolymer partial hydrolysate (EVOH), polyimide resins, polyetherimide resins, polysulfone resins, polyethersulfone resins, polyetheretherketone resins, polycarbonate resins, polyvinyl butyral resins, polyarylate resins, fluororesins, acrylic resins, biodegradable resins, etc. Among these, polyamide resins such as nylon 6 and polyester resins such as polyethylene terephthalate are preferred from the viewpoint of providing heat resistance and mechanical strength as an exterior material, and polyamide resins such as nylon 6 are more preferred from the viewpoint of improving the pinhole resistance of the metal layer. The reinforcing layer may be a single layer or two or more layers may be laminated. In the case of two or more layers, different resin layers may be selected, or the same resin layers may be selected.

[0069] There are no particular restrictions on the thickness of the reinforcing layer, but from the viewpoint of providing mechanical strength, it is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 15 μm or more. To ensure flexibility, it is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 30 μm or less.

[0070] <Battery Pack> The battery pack in one embodiment of the present invention comprises the spacer and single cell of the present invention. The battery pack of the present invention is applicable to battery packs mounted in, for example, electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), electric heavy machinery, electric motorcycles, electric assist bicycles, ships, aircraft, trains, uninterruptible power supplies (UPS), home energy storage systems, and battery storage systems for stabilizing power grids using renewable energy such as wind, solar, tidal, and geothermal power. However, the battery pack can also be used as a power source to supply power to devices other than the EVs mentioned above.

[0071] [Single Cell] Figure 3 is a plan view showing an example of a single cell constituting a battery pack, Figure 4 is a front view of the single cell shown in Figure 3, and Figure 5 is a right side view of the single cell. The single cell 200 is formed in the shape of a rectangular parallelepiped having a height direction (H), a width direction (W), and a thickness direction (D), and terminals 210 and 220 are provided on its upper surface. The single cell 200 is, for example, a lithium-ion secondary battery comprising a positive electrode and a negative electrode capable of intercalating and releasing lithium ions, as well as an electrolyte. In addition to lithium-ion secondary batteries, secondary batteries such as lithium-ion solid-state batteries, nickel-metal hydride batteries, nickel-cadmium batteries, and lead-acid batteries can also be used.

[0072] Figure 6 shows a top view of a battery pack 100 formed using multiple single cells 200, and Figure 7 is a schematic side view showing the battery pack 100 shown in Figure 6 with the side plate 300d removed. In Figures 6 and 7, the battery pack 100 includes a housing 300 and multiple single cells 200 housed within the housing 300. The housing 300 has a bottom plate 300e and side plates 300a, 300b, 300c, and 300d erected along the outer circumference of the bottom plate 300e. In Figures 6 and 7, five single cells 200 are shown as an example, but the number of single cells can be selected as appropriate.

[0073] In the housing 300, a plurality of single cells 200 are arranged in the thickness direction (D), and the above-described spacer 1 is disposed between the single cells 200. The positive electrode terminals (e.g., terminal 210) and the negative electrode terminals (e.g., terminal 220) of the adjacent (opposing) single cells 200 are electrically connected in series by the bus bar 301 through the spacer 1, whereby the assembled battery 100 outputs a predetermined power. As shown in FIG. 7, a spacer 1A is disposed between the upper surface of the bottom plate 300e of the housing 300 and each single cell 200. The spacer 1A has the same configuration as the spacer 1.

[0074] When a part or all of the chemical substances constituting the electrodes, electrolytic solution, etc. of the single cell 200 cause a decomposition reaction while generating heat inside the single cell 200, the temperature of the single cell 200 rises, and a part or all of the single cell 200 may reach 200°C or higher. In the present invention, this state is referred to as an "abnormal heat generation state".

[0075] Generally, regarding the safety of the positive electrode material among the materials constituting the single cell 200, it is known that the stability of the crystal structure after delithiation by charging has a great influence. LiCoO generally used as the positive electrode material ２ , Li(Ni １／３ Mn <- １／３ Co １／３ )O ２ , Li(Ni ０．８ Co ０．１５ Al ０．０５ )O ２These materials undergo crystalline breakdown accompanied by oxygen release at high temperatures when charged. The oxygen released from the positive electrode causes oxidation of the electrolyte, leading to a rapid exothermic reaction. Structural analysis using synchrotron radiation has reported that a crystalline phase transition occurs at around 200°C in the above-mentioned positive electrode materials. Therefore, if part or all of the cell 200 reaches a temperature of 200°C or higher, it means that crystal collapse of the positive electrode is progressing, that is, the cell 200 is in a thermal runaway state (Reference 1: High-Safety Technology and Materials for Lithium-Ion Batteries, CMC Publishing, p. 44 / Reference 2: J. Dahn et al., Electrochemistry Communication, 9, 2534-2540 (2007) / Reference 3: Hironori Kobayashi, "Evaluation and Analysis Techniques for Positive Electrode Materials for Lithium-Ion Secondary Batteries Using Synchrotron Radiation," Spring-8 Utilization Promotion Council Glass and Ceramics Research Group (Second Meeting) (2011)).

[0076] Furthermore, regarding the safety of the negative electrode material among the materials constituting the single cell 200, it is known that the charging negative electrode (lithium-inserted carbon negative electrode) basically exhibits strong reducing properties similar to those of lithium metal, and a protective film is formed on the negative electrode surface through reaction with the electrolyte, thereby suppressing further reactions. Therefore, the chemical composition, structure, and thermal stability of this protective film have a significant impact on the thermal stability of the charging negative electrode when the temperature rises. Typically, the reaction between the charging negative electrode and the electrolyte is explained by the formation of a protective film and the subsequent explosive reductive decomposition reaction due to film breakdown. Generally, it has been reported that the protective film formation reaction on the negative electrode proceeds from around 130°C, followed by the film decomposition reaction at around 200°C, and finally leads to an explosive reductive decomposition reaction. Therefore, if part or all of the single cell 200 reaches a temperature of 200°C or higher, it means that the coating on the negative electrode surface is degrading, that is, the single cell 200 is in a thermal runaway state (Reference 4: Battery Handbook 1st Edition, Ohmsha, p. 591 / Reference 5: The Cutting Edge of High-Safety Technology and Evaluation Technology for Lithium-ion Batteries, CMC Publishing, p. 90).

[0077] Furthermore, in this invention, the state in which the chemical substances constituting the electrodes, electrolyte, etc., that make up the single cell 200 do not undergo a decomposition reaction with a heat generation rate above a certain level inside the single cell 200 is referred to as the "normal state." Here, the heat generation state of the single cell 200 can be evaluated using ARC (Accelerating rate calorimetry), which is a means of quantitatively measuring the thermal behavior when reactive chemical substances undergo self-heating decomposition under adiabatic conditions. For example, Dahn et al. define that a self-heating reaction is progressing inside the cell when the heat generation rate observed in ARC exceeds 0.04°C / min, and this can be followed (Reference 6: J. Dahn et al., Electrochimica Acta, 49, 4599-4604 (2004)). Furthermore, in this invention, a single cell 200 in a normal state is referred to as a "single cell maintaining a normal state," and a single cell 200 that has deviated from a normal state and has not reached an abnormal heat generation state is referred to as a "single cell deviating from a normal state." Heat generated inside a single cell 200 is transmitted to other single cells 200 via various transmission paths. For example, heat generated inside a single cell 200 can be transmitted to other single cells 200 via the spacer 1.

[0078] For example, let's assume that the upper limit of the average surface temperature is 180°C when a single cell 200 in contact with or near spacer 1 deviates from its normal state and does not reach an abnormal heat generation state. Here, it is known that when the general-purpose separator material is made of polyethylene or polypropylene, its meltdown temperature is 160 to 200°C. Therefore, if the average surface temperature of the single cell 200 exceeds 180°C, a portion of the general-purpose separator material constituting the single cell 200 may melt down, potentially leading to an abnormal heat generation state.

[0079] Within a range where the average temperature of one of the two thickness-direction surfaces of the spacer 1 that separate the individual cells 200 constituting the battery pack 100 does not exceed 100°C, the spacer 1 can transfer heat from an individual cell 200 (e.g., cell 200a) in the battery pack 100 in its thickness direction, and transfer it to other individual cells 200 (cell 200b) or other components (e.g., the bottom plate 300e) that are facing cell 200a via the spacer 1. On the other hand, if the average temperature exceeds 100°C, the spacer 1 opens due to the heat, and the enclosed liquid flows out of the spacer in a gaseous or liquid phase state. This outflow allows air (which has an insulating effect) to enter the enclosed material 110 inside the spacer 1, increasing the insulating properties (thermal resistance) in the thickness direction. This prevents other individual cells 200 from deviating from their normal state when one individual cell 200 deviates from its normal state.

[0080] The configuration of the spacer and battery pack described above is merely an example, and can be modified as appropriate based on design requirements, etc., without departing from the spirit of the present invention.

[0081] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist of the invention.

[0082] (Example 1) As the exterior material, an aluminum laminate film cut into a rectangle of 100 mm in length and 160 mm in width (with a 15 μm thick biaxially oriented polyethylene terephthalate film (outer layer) as the protective resin layer, and a 12 μm thick metal layer with a moisture permeability of 5 × 10 －５ g / m ２ The aluminum layer and sealant resin layer of the / day material have a thickness of 30 μm and a moisture permeability of 15 g / m². ２Two sheets of linear low-density polyethylene (LLDPE) film (with a total thickness of 67 μm, including a 5 μm thick polyurethane adhesive layer between each layer) were stacked together, and the three sides were sealed by heat fusion (temperature 120°C, 3 seconds) with a sealing width of 1 cm to obtain an outer packaging bag. Next, an inner packaging material for the above was prepared. An inorganic layer (vermiculite sheet; thickness 1 mm) cut into a rectangle of 7 cm vertically and 13 cm horizontally, and an intermediate layer (unoriented polypropylene film) with a thickness of 50 μm cut into a rectangle of 7 cm vertically and 13 cm horizontally were alternately laminated in the order of inorganic layer, intermediate layer, inorganic layer, intermediate layer, inorganic layer (3 inorganic layers and 2 intermediate layers) so as not to protrude when viewed from above, to obtain a laminated inner packaging material. This laminated inner packaging material was placed inside the outer packaging bag with the three sides sealed as described above. In the spacer of this embodiment, the relationship between the areas of the third to fifth regions was S1' + S2' > S3 and S1' = S3. After injecting 15 g of water as a liquid into the unfused portion of the outer packaging material bag sealed on three sides, the unfused portion was sealed by heating and fusing with a sealing width of 1 cm, and the excess outer circumference was cut off to produce a spacer (referred to as spacer (1)) with a length of 90 mm, a width of 150 mm, and a thickness of 3.2 mm. In this spacer (1), the thickness of the resin layer joined at the periphery of the outer packaging material was 0.05 mm, and the width of the sealing portion at the periphery was 5 mm.

[0083] (Examples 2-4, Comparative Example 1) Spacers (2) to (5) were manufactured in the same manner as spacer (1) manufactured in Example 1, except for the material and thickness of the intermediate layer, the number of inorganic layers, and the number of intermediate layers shown in Table 1.

[0084] <Sealant resin layer - material> High-ret CPP: Unoriented polyethylene (melting point 150°C) <Intermediate layer - material> CPP: Unoriented polypropylene film (melting point 140°C) LDPE: Low-density polyethylene (melting point 110°C) PET: Polyethylene terephthalate (melting point 270°C)

[0085] <Method for Evaluating the Melting Point of Resin> Using a differential scanning calorimeter (model number "Diamond DSC") manufactured by PerkinElmer, a 5 mg sample of the resin to be measured was scraped off and placed in an aluminum pan to prepare a sample for measurement, in accordance with the method described in JIS K 7121:2012. The prepared sample was heated from 25°C to 200°C at a heating rate of 10°C / min, and the peak temperature in the endothermic region of the obtained DSC curve was defined as the melting point.

[0086] <Method for Evaluating Plateau Time> The thermal insulation properties of the spacers manufactured in each embodiment were evaluated using a test apparatus as shown in Figure 8. Specifically, in Example 1, a spacer 1 was placed on a 1 mm thick brass metal plate 403, and a 5 mm thick brass metal block 402 was set on top of the spacer 1. The metal plate 403, spacer 1, and metal block 402 were covered with thermal insulation material 401, except for the lower part of the metal plate 403. Nitrogen gas heated to 300°C by two tube heaters 404 was blown onto the metal plate 403 from below, and the temperature of the metal block 402 located on top of the spacer 1 was measured. The time during which the temperature of the metal block 402 measured in this heating test was maintained within the range of 100°C ± 5°C was measured as the plateau time. The results are shown in Table 1.

[0087] (Example 5) As the outer packaging material, two sheets of aluminum laminate film (containing nylon (outer) and polypropylene (inner) as resin layers, 0.12 mm thick), cut into rectangles of 14 cm in length and 18 cm in width, were stacked together and the three sides were heat-fused together with a sealing width of 1 cm (temperature 200°C, 3 seconds). Next, an inner packaging material for sealing the above was prepared. An inorganic layer (vermiculite sheet; 1 mm thick), cut into a rectangle of 7.6 cm in length and 13 cm in width, and an intermediate layer (polypropylene mesh) with a thickness of 1 mm, cut into a rectangle of 7.6 cm in length and 13 cm in width, were alternately laminated in the order of inorganic layer, intermediate layer, inorganic layer, so as not to protrude when viewed from above, to obtain a laminated inner packaging material 110. This laminated inner packaging material was placed inside the bag of the outer packaging material with the three sides sealed as described above. A spacer (referred to as spacer (6)) measuring 9.5 cm in length and 14.75 cm in width was fabricated by injecting 9 g of water as a liquid into the unfused portion of the exterior material, which had three sides sealed, and then sealing the unfused portion by heating and fusing it to a width of 1 cm, and then cutting off the excess outer circumference. The thickness of the resin layer joined at the periphery of the exterior material in spacer (6) was 50 μm, and the width of the sealed portion at the periphery was 5 mm. The V1 / ((S11 + S12) × D2) of the fabricated spacer was 0.25, 1-{V2 / (S11 × D2)} was 0.33, S1 / (S1 + S2) was 0.84, and P / S12 was 0.76 MPa / mm². ２ P / S2 is 0.76 MPa / mm ２ P / S5 is 0.60 MPa / mm ２ The ratio S1 / S4 was 0.70. Furthermore, the spacer satisfied the relationship S1 + S2 ≥ S3, and S1 = S3. The burst pressure of the spacer was 14.0 MPa and the plateau time was 925 seconds.

[0088] (Example 6) Spacer (7) was manufactured in the same manner as spacer (6) manufactured in Example 5, except that the amount of liquid was changed. The V1 / ((S11+S12)×D2) of the manufactured spacer was 0.21, 1-{V2 / (S11×D2)} was 0.33, S1 / (S1+S2) was 0.84, and P / S12 was 0.87 MPa / mm ２ P / S2 is 0.87 MPa / mm ２ P / S5 is 0.69 MPa / mm ２The ratio S1 / S4 was 0.70. Furthermore, the spacer satisfied the relationship S1 + S2 ≥ S3, and S1 = S3. The burst pressure of the spacer was 16.0 MPa and the plateau time was 775 seconds.

[0089] <Method for evaluating burst pressure> A metal plate (15 cm long, 10 cm wide, 1 cm thick; made of SUS430; Misumi Corporation) was placed on top of the spacer fabricated in each example, and a load was applied using a high-pressure jack (model number J-15; AS ONE Corporation). The burst pressure of the spacer was calculated by dividing the load at which the spacer burst by the area of ​​the internal space within the spacer.

[0090] 1 Spacer 100 Battery pack 110 Encapsulating material 111 Internal space 120 Outer material 120a Peripheral part, sealing part 120b Gap 200 Single cell 200a Single cell 200b Single cell 210 Terminal 220 Terminal 300 Housing 300a Side plate 300b Side plate 300c Side plate 300d Side plate 300e Bottom plate 301 Bus bar 401 Insulation material 402 Brass metal block 403 Brass metal plate 404 Tube heater S1 First area S2 Second area

Claims

1. A spacer having a thickness direction and a planar direction perpendicular thereto, and partitioning between single cells or between a single cell and a component other than the single cell in the thickness direction, wherein the spacer comprises an insulating portion including a first inorganic layer, a first intermediate layer, and a second inorganic layer laminated in the thickness direction, the first intermediate layer being a resin layer, the first intermediate layer in contact with the first inorganic layer and the second inorganic layer, and the spacer further containing a liquid.

2. The spacer according to claim 1, wherein the spacer includes a sealing portion, and in a plan view from the thickness direction of the spacer, the area S11 of a first region excluding the sealing portion where the exterior material and the insulating portion overlap, the area S12 of a second region excluding the sealing portion where the exterior material and the insulating portion do not overlap, the thickness D2 of the insulating portion, and the volume V1 of the liquid satisfy the following formula 1. Formula 1: 0.05 ≤ V1 / ((S11 + S12) × D2) 3. The spacer according to claim 2, wherein the burst pressure P of the spacer is 9.0 to 30.0 MPa.

4. The spacer according to claim 2, wherein the burst pressure P of the spacer is 11.0 to 30.0 MPa.

5. The ratio of the burst pressure P of the spacer to the area S12 of the second region, P / S12, is 0.60 to 2.0 MPa / mm². ２ The spacer according to claim 2.

6. The ratio of the burst pressure P of the spacer to the area S12 of the second region, P / S12, is 0.70 to 2.0 MPa / mm². ２ The spacer according to claim 2.

7. The spacer according to claim 2, wherein the area S11 of the first region, the thickness D2 of the insulating portion, and the volume V2 of the inorganic layer satisfy the following formula 2: Formula 2: 0.01 ≤ 1 - {V2 / (S11 × D2)} ≤ 0.9 8. The spacer according to claim 1, wherein the spacer includes a sealing portion, the area S1 of a first region excluding the sealing portion where the exterior material and the first inorganic layer overlap, the area S2 of a second region excluding the sealing portion where the exterior material and the first inorganic layer do not overlap, and the area S3 of a third region where the exterior material and the first intermediate layer overlap, satisfy the following formula 3. Formula 3: S1 + S2 ≥ S3 9. The spacer according to claim 8, wherein the area S1 of the first region and the area S2 of the second region satisfy the following formula 4: Formula 4: 0.60 ≤ S1 / (S1 + S2) ≤ 1.0 10. The spacer according to claim 8, wherein the area S1 of the first region and the area S2 of the second region satisfy 0.84 ≤ S1 / (S1 + S2) ≤ 0.

95.

11. The spacer according to claim 8, wherein, in a plan view from the thickness direction of the spacer, the ratio S1 / S4 of the area of ​​the first region to the area S4 of the spacer is 0.60 to 1.

0.

12. The spacer according to claim 8, wherein, in a plan view from the thickness direction of the spacer, the ratio S1 / S4 of the area of ​​the first region to the area S4 of the spacer is 0.65 to 0.

95.

13. The spacer according to claim 8, wherein the first intermediate layer does not come into contact with the exterior material.

14. The exterior material includes a sealing portion, and the ratio of the bursting pressure P of the spacer to the area S5 of the sealing portion in a plan view from the thickness direction, P / S5, is 0.30 to 2.0 MPa / mm². ２ The spacer according to claim 1.

15. The exterior material includes a sealing portion, and the ratio P / S5 of the bursting pressure P of the spacer to the area S5 of the sealing portion in a plan view from the thickness direction is 0.50 to 2.0 MPa / mm². ２ The spacer according to claim 1.

16. The spacer according to claim 1, wherein when the average surface temperature of the spacer is 80°C or higher, the liquid is discharged to the outside of the spacer.

17. The spacer according to claim 1, further comprising a mixed layer of an inorganic layer and a resin layer between the first inorganic layer and the first intermediate layer.

18. The spacer according to claim 1, wherein the exterior material includes a sealant resin layer and a metal layer, and the difference between the melting point of the resin contained in the first intermediate layer and the melting point of the resin contained in the sealant resin layer of the exterior material is 60°C or less.

19. The spacer according to claim 1, wherein the exterior material comprises a sealant resin layer and a metal layer, and the difference between the melting point of the resin contained in the first intermediate layer and the melting point of the resin contained in the sealant resin layer of the exterior material is 20°C or less.

20. The spacer according to claim 1, wherein the thickness of the first intermediate layer is 0.01 to 0.1 mm.

21. The spacer according to claim 1, wherein the thickness of the first intermediate layer is 0.1 to 3 mm.

22. A battery pack comprising the spacer and single cell described in claim 1.

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