Spacer for battery cell, method for manufacturing same, and battery module including spacer for battery cell

Abstract

A spacer 10 for battery cell according to the present embodiment is used for a battery module 20 including a plurality of lithium secondary battery cells 11 and the spacers 10 for battery cell, each of the spacers 10 being interposed between adjacent ones of the lithium secondary battery cells 11. The spacer for battery cell includes a GW layer including binder resin and glass wool. A difference between a compression rate C1 (%) at a load at a surface pressure of 0.5 MPa and a compression rate C2 (%) at the time of unloading at a surface pressure of 0.5 MPa is 20% or less in a compression ratio-surface pressure displacement curve of the GW layer.

Description

Battery cell spacer, manufacturing method thereof, and battery module using battery cell spacer

[0001] The present invention relates to a battery cell spacer, a manufacturing method thereof, and a battery module using the battery cell spacer.

[0002] Conventionally, battery cell spacers have been required to have various properties, such as shock-absorbing properties, flame retardancy, and thermal insulation, and efforts are underway to develop battery cell spacers that meet the desired properties. For example, it is known that battery cells repeatedly expand and contract with charging and discharging, gradually increasing the distance between electrodes within the battery cell and resulting in a decline in battery performance. Patent Document 1 therefore discloses a silicone rubber member for secondary batteries that contains a specific organopolysiloxane, a hollow filler, a flame retardant, and a curing agent in order to simultaneously achieve shock-absorbing properties, flame retardancy, and thermal insulation.

[0003] On the other hand, in order to obtain flame retardancy, Patent Document 2 discloses a lithium-ion battery in which a member made by impregnating short-fiber glass wool with phenolic resin and shaping the member is sandwiched between multiple lithium-ion battery cells. It also discloses that by using a member made by impregnating short-fiber glass wool with phenolic resin and shaping the member, lithium-ion batteries can be manufactured more cheaply than when mica is used as a heat insulating material.

[0004] Glass wool is also known as a flame-retardant material (Non-Patent Document 1).

[0005] JP 2023-171019 A JP 2022-107984 A

[0006] Ministry of Land, Infrastructure, Transport and Tourism "Definition of Non-combustible Materials" (No. 1178, September 29, 2004)

[0007] However, the battery cell spacers disclosed in Patent Documents 1 and 2 still have room for improvement in terms of improving shock-absorbing performance.

[0008] Therefore, an object of the first invention is to improve the cushioning performance of the battery cell spacer.

[0009] Furthermore, the present inventors have conducted extensive research into battery cell spacers that are made by impregnating glass wool with resin and shaping it, rather than using silicone rubber as described in Patent Document 1, in order to improve the compressive modulus while maintaining flame retardancy. As a result, they found that the technology described in Patent Document 2 had room for improvement in terms of obtaining an excellent compressive modulus.

[0010] Therefore, the second invention aims to provide a battery cell spacer made by impregnating glass wool with resin and shaping it, which has excellent compressive elastic modulus while maintaining flame retardancy.

[0011] The inventors of the present invention have conducted extensive research to improve the cushioning performance to a higher level, and have devised a new index by focusing on the compressibility at a surface pressure of 0.5 MPa in the compressibility-surface pressure displacement curve obtained when a GW layer is loaded up to a surface pressure of 1.5 MPa and then the load is removed. That is, they have found that controlling the difference between the compressibility C1 (%) under load and the compressibility C2 (%) when the surface pressure is removed from 0.5 MPa as an index is effective in solving the problems, and have completed the first invention.

[0012] That is, according to a first invention, there is provided a battery cell spacer used in a battery module including a plurality of lithium secondary battery cells and a battery cell spacer interposed between adjacent lithium secondary battery cells, wherein the battery cell spacer has a GW layer containing a binder resin and glass wool, and in a compression rate-contact pressure displacement curve of the GW layer, the difference between the compression rate C1 (%) when loaded at a contact pressure of 0.5 MPa and the compression rate C2 (%) when unloaded at a contact pressure of 0.5 MPa is 20% or less.

[0013] Furthermore, the inventor discovered that in a battery cell spacer made by impregnating glass wool with resin and shaping it, controlling the volume fraction and fiber diameter of the glass wool while controlling the proportion of the glass wool is effective in solving the problem, and thus completed the second invention.

[0014] That is, according to a second invention, there is provided a battery cell spacer used in a battery module including a plurality of lithium secondary battery cells and a battery cell spacer interposed between adjacent lithium secondary battery cells, wherein the battery cell spacer has a GW layer containing a binder resin and glass wool, the GW layer has a volume fraction of the glass wool of 1 to 30% and a thickness of 1 to 20 mm, the average fiber diameter of the glass wool is 3 to 20 μm, and the mass ratio of the binder resin to the glass wool is 3 to 40 mass%.

[0015] According to the present invention, the following battery cell spacer and related technology are provided.

[0016] [1] A battery cell spacer used in a battery module including a plurality of lithium secondary battery cells and a battery cell spacer interposed between adjacent lithium secondary battery cells, the battery cell spacer having a GW layer containing a binder resin and glass wool, wherein in a compressibility-contact pressure displacement curve of the GW layer, the difference between the compressibility C1 (%) when loaded at a contact pressure of 0.5 MPa and the compressibility C2 (%) when unloaded at a contact pressure of 0.5 MPa is 20% or less. [2] The battery cell spacer according to [1], wherein the GW layer has a glass wool volume fraction of 1 to 30% and a thickness of 1 to 20 mm. [3] The battery cell spacer according to [1] or [2], wherein the glass wool has an average fiber diameter of 3 to 20 μm. [4] The battery cell spacer according to any one of [1] to [3], wherein the mass ratio of the binder resin to the glass wool is 20 mass% or less. [5] The battery cell spacer is used in a battery module including a plurality of lithium secondary battery cells and a battery cell spacer interposed between adjacent lithium secondary battery cells, wherein the battery cell spacer has a GW layer containing a binder resin and glass wool, wherein the GW layer has a glass wool volume fraction of 1 to 30% and a thickness of 1 to 20 mm, wherein the glass wool has an average fiber diameter of 3 to 20 μm, and wherein the mass ratio of the binder resin to the glass wool is 3 to 40 mass%. [6] The battery cell spacer according to [5], wherein the glass wool volume fraction of the GW layer is 8 to 30%. [7] The battery cell spacer according to any one of [1] to [6], wherein the thermal conductivity of the GW layer in the stacking direction at 25°C is 0.025 to 0.050 W / m·K.[8] The battery cell spacer according to any one of [1] to [7], wherein the compressive elastic modulus of the GW layer at a surface pressure of 1 MPa, calculated from the slope of the GW layer's compressibility-surface pressure displacement curve at a surface pressure of 1 MPa under load, is 2 to 30 MPa. [9] The battery cell spacer according to any one of [1] to [8], wherein the GW layer satisfies the following condition a: (Condition a) In the GW layer's compressibility-surface pressure displacement curve, when the surface pressure at a compression rate of 10% is P10 (MPa) and the surface pressure at a compression rate of 25% is P25 (MPa), P25 / P10 is 1 or more and 50 or less.

[10] The battery cell spacer according to any one of [1] to [9], wherein the binder resin comprises one or more selected from the group consisting of phenolic resin, urea resin, acrylic resin, sugar-based binder, polyvinyl alcohol-based resin, and polyethylene glycol-based resin.

[11] The battery cell spacer according to any one of [1] to

[10] , wherein at least a portion of the GW layer is coated with one or more selected from the group consisting of woven fabric, nonwoven fabric, paper, resin film, and metal foil.

[12] A battery module comprising the battery cell spacer according to any one of [1] to

[11] .

[13] A method for manufacturing a battery cell spacer used in a battery module including a plurality of lithium secondary battery cells and a battery cell spacer interposed between adjacent lithium secondary battery cells, the method comprising the step of performing a first press involving heating on glass wool to which a binder resin has been adhered, to form a GW layer containing the binder resin and the glass wool.

[14] A method for manufacturing a battery cell spacer according to

[13] , wherein the first press is performed at 150 to 350°C and 0.005 to 1.5 MPa.

[15] A method for manufacturing a battery cell spacer according to

[13] or

[14] , further comprising the step of adhering a binder resin to the glass wool before the step of forming the GW layer.

[16] A method for manufacturing a battery cell spacer according to any one of

[13] to

[15] , wherein the binder resin comprises one or more resins selected from the group consisting of phenol resin, urea resin, acrylic resin, sugar-based binder, polyvinyl alcohol-based resin, and polyethylene glycol-based resin.

[17] A method for manufacturing a battery cell spacer according to any one of

[13] to

[16] , wherein the glass wool to which the binder resin is adhered has a basis weight of 500 to 5000 g / m. ２

[18] A method for manufacturing a battery cell spacer according to any one of

[13] to

[17] , wherein the mass ratio of the binder resin to the glass wool is 20 mass% or less.

[19] A method for manufacturing a battery cell spacer according to any one of

[13] to

[18] , wherein a second pressing is further performed after the first pressing to form the GW layer.

[20] A method for manufacturing a battery cell spacer according to

[19] , wherein the second pressing is performed at 100°C or less.

[21] A method for manufacturing a battery cell spacer according to

[19] or

[20] , wherein the pressing pressure of the second pressing is higher than the pressing pressure of the first pressing.

[22] The method for manufacturing a battery cell spacer according to any one of

[19] to

[21] , wherein the pressing pressure of the second press is 0.1 to 50 MPa.

[0017] According to the present invention, it is possible to provide a battery cell spacer with improved cushioning performance, a battery cell spacer that can exhibit an excellent compressive elastic modulus while maintaining flame retardancy, and a battery module that uses these spacers.

[0018] FIG. 1 is a perspective view schematically showing an example of a battery module including a battery cell spacer according to the present embodiment; FIG. 2 is a perspective view schematically showing another example of a battery module including a battery cell spacer according to the present embodiment; FIG. 3 is a diagram showing a compressibility-surface pressure displacement curve obtained in a compression test of Example 1B; FIG. 4 is a diagram showing a compressibility-surface pressure displacement curve obtained in a compression test of Example 2B; FIG. 5 is a diagram showing a compressibility-surface pressure displacement curve obtained in a compression test of Example 3B; and FIG. 6 is a diagram showing a compressibility-surface pressure displacement curve obtained in a compression test of Example 4B.

[0019] In this specification, the expression "X to Y" in the description of a range of values ​​means not less than X and not more than Y, unless otherwise specified.

[0020] Below, we will explain a battery cell spacer according to an embodiment of the present disclosure and a battery module using the spacer. However, the embodiments of the present disclosure should not be interpreted as being limited to the following embodiments and examples. Furthermore, the combinations of the respective components are not limited.

[0021] <Battery Cell Spacer> Fig. 1 is a perspective view that schematically shows an example of a battery module 20 that includes a battery cell spacer 10 according to the present embodiment. As shown in Fig. 1, the battery module 20 according to the present embodiment includes a plurality of lithium secondary battery cells 11 and battery cell spacers 10 that are interposed between adjacent lithium secondary battery cells 11. The battery cell spacer 10 is used in this battery module 20.

[0022] More specifically, as a first example, the battery cell spacer 10 has a GW layer containing a binder resin and glass wool, and in the compressibility-surface pressure displacement curve of the GW layer, the difference between the compressibility C1 (%) under load at a surface pressure of 0.5 MPa and the compressibility C2 (%) under unload at a surface pressure of 0.5 MPa is 20% or less. This improves cushioning performance. In other words, the compressibility-surface pressure displacement curve of the GW layer of the battery cell spacer 10 in this embodiment assumes expansion and contraction associated with charging and discharging of the lithium secondary battery cells 11. It is believed that by simultaneously controlling the compressibility under load and unloading, cushioning performance can be improved with greater precision.

[0023] In the compressibility-surface pressure displacement curve of the GW layer of the battery cell spacer 10, the difference between the compressibility C1 (%) when loaded at a surface pressure of 0.5 MPa and the compressibility C2 (%) when unloaded at a surface pressure of 0.5 MPa is 20% or less, preferably 18% or less, more preferably 16% or less, and even more preferably 14% or less, 12% or less, 10% or less, 8% or less, 6% or less, 5% or less, and 4% or less in this order. The difference between C1 and C2 may be within a range between any two of the following values: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20% (including any value between these values ​​in increments of 0.1%).

[0024] The compressibility C1 (%) under a load of 0.5 MPa is preferably 2% or more, more preferably 4% or more, and even more preferably 6% or more. By setting the compressibility C1 to the above-mentioned lower limit or higher, it is possible to control the cushioning performance at a higher level. The compressibility C1 (%) under a load of 0.5 MPa is preferably 60% or less, more preferably 40% or less, and even more preferably 30% or less. Setting the compressibility C1 to the above-mentioned upper limit or lower makes it easier to improve the cushioning performance. C1 may be within a range between any two of the following values: 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30, 35, 40, 45, 50, 55, or 60% (including any value between these values ​​in increments of 0.1%).

[0025] The compressibility C2 (%) when unloaded at a surface pressure of 0.5 MPa is preferably 4% or more, more preferably 6% or more, and even more preferably 8% or more. By setting the compressibility C2 to the above-mentioned lower limit or more, it is possible to control the cushioning performance at a higher level. The compressibility C2 (%) when unloaded at a surface pressure of 0.5 MPa is preferably 80% or less, more preferably 60% or less, and even more preferably 40% or less. Setting the compressibility C2 to the above-mentioned upper limit or less makes it easier to improve the cushioning performance. C1 may be within a range between any two of the following values: 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, or 80% (including any value between these values ​​in increments of 0.1%).

[0026] The difference between the compression rates C1 and C2 in the battery cell spacer 10 can be achieved by selecting the materials constituting the battery cell spacer 10 and adjusting the manufacturing method accordingly, for example, by adjusting the volume fraction, thickness, and average fiber diameter of the glass wool in the GW layer, adjusting the amount of resin, adjusting the temperature and pressure of the first press in the process of forming the GW layer, performing the press in two stages, etc.

[0027] In the compression rate-surface pressure displacement curve of the battery cell spacer 10, the compressive elastic modulus at a surface pressure of 1 MPa is preferably 2 MPa or more, more preferably 3 MPa or more, and even more preferably 5 MPa or more. This allows the compressive elastic modulus to be improved while maintaining good cushioning properties. Meanwhile, in the compression rate-surface pressure displacement curve of the battery cell spacer 10, the compressive elastic modulus at a surface pressure of 1 MPa is preferably 30 MPa or less, more preferably 25 MPa or less. This allows the cushioning properties to be improved while maintaining a good compressive elastic modulus.

[0028] As a second example, the battery cell spacer 10 has a GW layer containing a binder resin and glass wool, where the GW layer has a glass wool volume fraction of 1 to 30%, a thickness of 5 to 20 mm, an average fiber diameter of the glass wool of 3 to 20 μm, and a mass ratio of the binder resin to the glass wool of 3 to 40 mass%. In other words, by having a predetermined GW layer, the battery cell spacer 10 achieves high flame retardancy and an excellent compressive modulus. Furthermore, by controlling the volume fraction (porosity) of the glass wool, a good balance between compressive modulus and thermal insulation can be achieved.

[0029] Below, each component of the battery cell spacer 10 of this embodiment will be described in detail.

[0030] [GW Layer] The battery cell spacer 10 includes a GW layer. The GW layer contains a binder resin and glass wool. The binder resin is added to maintain the glass wool in a predetermined shape and adheres to the glass wool so as to connect the intersections and contact points of the glass wool. Specifically, for example, the GW layer can be formed by heating and pressurizing an uncured glass wool fiber web that has been collected by adhering a binder resin to glass wool.

[0031] The GW layer may contain additives other than the binder resin and glass wool as needed, for example, a binder resin composition containing a binder resin and any additives may be attached to glass wool. In addition, the GW layer is preferably made of only the binder resin and glass wool in order to obtain high flame retardancy.

[0032] (Volume Fraction of Glass Wool) The volume fraction of glass wool in the GW layer is preferably 30% or less, more preferably 25% or less, and even more preferably 20% or less. This allows for improved heat insulation while obtaining flame retardancy, good compressive modulus, and cushioning properties. From the perspective of improving heat insulation, the volume fraction of glass wool may be 17% or less, 15% or less, or 10% or less. On the other hand, the volume fraction of glass wool in the GW layer is preferably 1% or more, more preferably 3% or more, even more preferably 5% or more, and particularly preferably 6% or more. This allows for improved compressive modulus while maintaining heat insulation. From the perspective of improving the compressive modulus, the volume fraction of glass wool may be 10% or more, 15% or more, or 17% or more. The volume fraction of glass wool in the GW layer may be within a range between any two of the following values: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30% (including any value in increments of 0.1% between these values).

[0033] The volume fraction of glass wool can be calculated as follows. First, the density of the glass used in the glass wool is measured. The density of the glass used in the glass wool can be measured by either pumping out a portion of the glass raw material during the production of the glass wool and measuring the cooled glass fragments, or by remelting the glass wool to produce glass fragments. When remelting the glass wool to produce glass fragments, for example, the procedure is as follows. The binder resin is removed from the glass wool by heating or other operations, and the glass wool is melted at 1000°C or higher to obtain a glass melt, which is then suitably shaped and slowly cooled to prepare a measurement sample. The glass density (kg / m) of the sample produced by these methods is measured using a known density measurement method such as the Archimedes method or the gas displacement method. ３ Separately, the weight of the GW layer is measured, and then the binder resin is removed from the GW layer by heating or other operations to determine the weight of the binder resin that was attached to the glass wool. The weight of the GW layer excluding the binder resin (weight of the glass wool) and the glass density of the glass wool (kg / m ３On the other hand, the volume of the GW layer is determined by measuring the dimensions of the GW layer, and the volume of the glass wool relative to the volume of the GW layer is expressed as a percentage, thereby determining the volume ratio (%) of the glass wool.

[0034] (Thickness) The GW layer preferably has a thickness of 1 mm or more, more preferably 1.5 mm or more, more preferably 2 mm or more, and even more preferably 3 mm or more. This not only ensures sufficient thermal insulation and minimizes the impact on adjacent battery cells in the event of an abnormality, but is also expected to serve as a good buffer against expansion and contraction of the battery cells. Meanwhile, the GW layer preferably has a thickness of 20 mm or less, preferably 15 mm or less, more preferably 13 mm or less, and even more preferably 10 mm or less. The thickness may also be 5 mm or less, 3 mm or less, or 2 mm or less. This allows battery cells to be efficiently arranged even in a narrow space while maintaining buffering properties. The thickness of the GW layer may be within a range between any two of the following values: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 mm (including any value in 0.1 mm increments between these values).

[0035] (Thermal Conductivity) The thermal conductivity at 25°C in the stacking direction of the GW layer is preferably 0.025 W / m·K or more, more preferably 0.030 W / m·K or more. This allows for a good compressive modulus while maintaining sufficient thermal insulation. On the other hand, the thermal conductivity at 25°C in the stacking direction of the GW layer is preferably 0.050 W / m·K or less. This allows for good thermal insulation. The thermal conductivity may be within a range between any two of the following values: 0.025, 0.030, 0.035, 0.040, 0.045, and 0.050 W / m·K (including any value between these values ​​in increments of 0.001 W / m·K).

[0036] (Thermal Conductivity) The thermal conductivity of the GW layer in the stacking direction at 300°C is preferably 0.15 W / m·K or less, and more preferably 0.1 W / m·K or more. This allows sufficient thermal insulation to be maintained even in high-temperature environments. On the other hand, the thermal conductivity of the GW layer in the stacking direction at 300°C is preferably 0.05 W / m·K or less. The thermal conductivity may be within a range between any two of the following values: 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, and 0.15 W / m·K (including any value between these values ​​in increments of 0.01 W / m·K).

[0037] Furthermore, the ratio of the thermal conductivity at 300°C divided by the thermal conductivity at 80°C is preferably 2.5 times or less, more preferably 2.2 times or less, and particularly preferably 2.0 times or less. This prevents an increase in thermal conductivity in high-temperature environments. The ratio may be within a range between any two of the following values: 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, and 2.5 times.

[0038] (Compressive modulus) The compressive modulus of the GW layer at a surface pressure of 1 MPa is preferably 2 MPa or more, more preferably 3 MPa or more, and even more preferably 5 MPa or more. This allows the compressive modulus to be improved while maintaining thermal insulation. Furthermore, from the viewpoint of increasing the compressive modulus, it is more preferable in this order to be 10 MPa or more, 15 MPa or more, and 20 MPa or more. On the other hand, the compressive modulus of the GW layer at a surface pressure of 1 MPa is preferably 30 MPa or less, more preferably 25 MPa or less. This allows the thermal insulation to be improved while obtaining flame retardancy and a good compressive modulus. Furthermore, from the viewpoint of increasing thermal insulation, it is more preferable in this order to be 20 MPa or less, 15 MPa or less, and 10 MPa or less. The compressive modulus of the GW layer at a surface pressure of 1 MPa may be within a range between any two of the following values: 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 MPa (including any value in increments of 0.1 MPa between these values).

[0039] Furthermore, it is preferable that the GW layer of this embodiment satisfies the following condition a: (Condition a) In the compression ratio-surface pressure displacement curve of the GW layer, when the surface pressure at a compression ratio of 10% is P10 (MPa) and the surface pressure at a compression ratio of 25% is P25 (MPa), P25 / P10 is 1 or more and 50 or less.

[0040] Under condition a, P25 / P10 is preferably 2 or more, and from the viewpoint of obtaining a high compressive elastic modulus, more preferably 4 or more, and even more preferably 5 or more. On the other hand, under condition a, P25 / P10 is preferably 50 or less, and from the viewpoint of improving heat insulating properties, more preferably 40 or less, even more preferably 20 or less, particularly preferably 10 or less, and even more preferably 8 or less. P25 / P10 may be within a range between any two of the following numbers: 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50 (including any value in increments of 0.1 between these values).

[0041] Furthermore, in the compression ratio-surface pressure displacement curve of the GW layer, the compression ratio at a surface pressure of 0.5 MPa is preferably 10% or more and 60% or less. This allows for a good balance between the compressive modulus of elasticity and heat insulation. From the viewpoint of improving heat insulation, the compression ratio at a surface pressure of 0.5 MPa is preferably 20% or more, more preferably 30% or more. On the other hand, from the viewpoint of improving the compressive modulus of elasticity, the compression ratio at a surface pressure of 0.5 MPa is preferably 70% or less, more preferably 60% or less.

[0042] A GW layer satisfying the above-mentioned glass wool volume ratio, thermal conductivity, and compressive modulus can be realized by adjusting the heating and pressurizing conditions in the manufacturing method of the GW layer described below, or by adjusting the basis weight of the glass wool, the amount of binder resin, etc.

[0043] The GW layer may be a single layer or a multilayer in which multiple GW layers are stacked, but even if the GW layer is multilayered, the same physical properties and effects as those described above can be obtained.

[0044] Furthermore, the GW layer of this embodiment maintains the above-described physical properties and effects even when repeatedly compressed. In other words, even when the battery module 20 using the GW layer of this embodiment is repeatedly used, the GW layer maintains a stable compressive elastic modulus, improving the reliability and durability of the battery module 20. For example, when a repeated compression test is performed, it is preferable that the compression rate at the same surface pressure for the fifth compression test be 50% or more of the compression rate for the first compression test.

[0045] (Glass wool) Glass wool is a short glass fiber, and is distinguished from glass fiber, which is a typical long fiber.

[0046] The average fiber diameter of the glass wool is preferably 3 μm or more, more preferably 3.5 μm or more, and even more preferably 4 μm or more. This improves cushioning properties and enables efficient production. On the other hand, the average fiber diameter of the glass wool is preferably 20 μm or less, more preferably 15 μm or less, even more preferably 10 μm or less, and even more preferably 8 μm or less. This allows for cushioning properties to be obtained while suppressing air convection, thereby achieving desired thermal insulation. The average fiber diameter of the glass wool may be within a range between any two of the following values: 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20 μm (including any value in 0.1 μm increments between these values).

[0047] The average fiber diameter of glass wool is defined as the average value obtained by sampling approximately 20 g of glass wool from three random locations within the article, sampling 20 fibers from each sampling location, and dividing the sum of the outer diameter values ​​by the number of measurements.

[0048] The average fiber length of glass wool is defined as the average value obtained by measuring the lengths of the fibers extracted when measuring the average fiber diameter and dividing the sum of the values ​​by the number of measurements, i.e., by sampling approximately 20 g of fibers from any three locations in the article, sampling 20 more fibers from each sampling point, and dividing the sum of the respective length values ​​by the number of measurements.

[0049] The average fiber length of the glass wool is preferably 1 mm or more, more preferably 3 mm or more, and may be 5 mm or more, or 10 mm or more. This makes it easier to form into a desired shape. On the other hand, the average fiber length of the glass wool is preferably 500 mm or less, more preferably 300 mm or less, and even more preferably 200 mm or less, and may be 100 mm or less, or 80 mm or less. This can improve the heat insulation.

[0050] (Binder Resin) The binder resin adheres to the intersections and contact points of the glass wool, thereby enabling the glass wool to be shaped into a predetermined shape.

[0051] The binder resin can be any thermosetting resin that hardens due to the heat generated during the first pressing step, but suitable resins include one or more selected from phenolic resins, urea resins, acrylic resins, sugar-based binders, polyvinyl alcohol-based resins, and polyethylene glycol-based resins. The sugar-based binders are known binders containing sugars as their main component, which are capable of obtaining mechanical properties such as strength and elastic modulus upon heating. Examples of sugars include disaccharides such as trehalose, isotrehalose, sucrose, and isosucrose, and trisaccharides such as raffinose.

[0052] Among these, it is preferable to contain a phenolic resin. This allows the phenolic resin to adhere well to the glass wool, and allows a superior compressive modulus to be obtained while maintaining flame retardancy. The phenolic resin is preferably a water-soluble phenolic resin in terms of its ability to be impregnated into the glass wool, and examples of such phenolic resins include resol-type phenolic resins and urea-modified resol-type phenolic resins.

[0053] The mass ratio of the binder resin to the glass wool is preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 3% by mass or more, particularly preferably 5% by mass or more, even more preferably 7% by mass or more, and even more preferably 10% by mass or more. This allows the glass wool to be molded into an appropriate shape and maintain that shape, thereby improving cushioning properties. On the other hand, the mass ratio of the binder resin to the glass wool is preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, particularly preferably 18% by mass or less, and even more preferably 15% by mass or less. This allows the amount of binder resin used to be reduced, preventing increases in weight and cost while still providing cushioning properties. The mass ratio of the binder resin to the glass wool may be within a range between any two of the following values: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40% by mass (including any value in increments of 0.1% by mass between these values).

[0054] At least a portion of the outer surface of the GW layer may be coated with one or more materials selected from woven fabric, nonwoven fabric, paper, resin film, and metal foil. This prevents the glass wool from fluffing and provides a good appearance and feel. The coating method for the GW layer can be a known method. The coating is not limited to a continuous coating, and may include discontinuous portions.

[0055] The woven fabrics and nonwoven fabrics may be formed using one or more materials selected from natural fibers, inorganic fibers, and synthetic fibers. Examples of natural fibers include cellulose (paper) and keratin. Examples of inorganic fibers include glass fibers and alumina fibers. Examples of synthetic fibers include polyester, polyamide, polyolefin, and polyurethane. The manufacturing method for paper, woven fabric, or nonwoven fabric is not particularly limited. For example, for nonwoven fabrics, known manufacturing methods such as flash spinning, meltblowing, spunbonding, and spunlace can be used. The weaving method for woven fabrics is not particularly limited, and known weaving methods can be used. Examples of the resin films include films made using one or more materials selected from polyethylene, ethylene copolymers, polypropylene, polyvinyl chloride, polystyrene, (meth)acrylic resins, polyester resins, and polyamide resins. Examples of the metal foils include thinly rolled foils of metals such as aluminum, stainless steel, copper, and alloys of these materials with other metals added. These may be used alone or in combination.

[0056] The battery cell spacer 10 of this embodiment may have multiple protrusions on its surface. The protrusions can be used to adjust the cushioning performance of the battery cell spacer 10. There are no particular limitations on the shape, size, number, and position of the protrusions, but for example, the protrusions can be cylindrical, truncated conical, prismatic, truncated pyramidal, or hemispherical in shape, with a diameter of 1 to 20 mm and a height of 1 to 20 mm, and the total area of ​​the multiple protrusions can be 1 to 50% of the surface of the spacer on which the protrusions are located.

[0057] The unevenness can be formed by a known method, for example, by using a mold having unevenness during heating and pressurization as described below.

[0058] <Method for manufacturing battery cell spacer 10> An example of a method for manufacturing a battery cell spacer 10 used in a battery module 20 including a plurality of lithium secondary battery cells 11 and a battery cell spacer 10 interposed between adjacent lithium secondary battery cells 11 will be described.

[0059] The manufacturing method of the battery cell spacer 10 of this embodiment includes a step of performing a first press with heating on the glass wool to which the binder resin has been attached, to form a GW layer made of the binder resin and the glass wool. The manufacturing method may further include a step of attaching the binder resin to the glass wool before the step of forming the GW layer.

[0060] Each step will be described below.

[0061] (Step 1) Step 1 is a step of producing glass wool with a binder resin attached. Glass wool can be produced by known methods such as the centrifugal method, the flame method, and the blowing method. For example, in the centrifugal method, molten glass adjusted to a predetermined viscosity is poured into a round container with multiple holes on the side, and the container is rotated at high speed. The centrifugal force causes the molten glass to flow out of the side holes of the container and further stretch it, thereby producing fiberized glass wool. If fiberization is difficult using only the heat carried over from the molten glass, fiberization may be assisted by a burner or the like. The glass wool produced by these production methods may have, for example, an average fiber diameter of 3 to 20 μm and an average fiber length of 1 mm or more and 500 mm or less.

[0062] Next, a binder resin is adhered to the glass wool. The method for adhering the binder resin is not particularly limited, but for example, a method of adhering the binder resin to the glass wool using a spray nozzle or the like can be mentioned. When any additive is used as the GW layer, a binder resin composition obtained by mixing the binder resin and the additive may be adhered to the glass wool. The basis weight of the obtained glass wool to which the binder resin is adhered is preferably 500 to 5000 g / m ２ and more preferably 600 to 4000 g / m ２and more preferably 700 to 3000 g / m ２ By setting the basis weight to the above lower limit or more, good flame retardancy and compressive modulus can be obtained, and by setting the basis weight to the above upper limit or less, it is easy to improve heat insulating properties. The basis weight of the glass wool is 500, 600, 700, 800, 900, 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500, and 5000 g / m ２ (1 g / m between these values ２ The value may be within a range between any two of the values ​​(including any value per unit area).

[0063] Although the production of the glass wool and the attachment of the binder resin may be carried out in separate steps, it is preferable to spray the binder resin onto the glass wool immediately after production, as this allows the binder resin to be attached uniformly to the glass wool. For example, when the glass wool is produced by the centrifugal method, it is preferable to spray the binder resin onto the area where the glass wool produced by the centrifugal method has been blown away.

[0064] In this embodiment, after step 1, the glass wool to which the binder resin has been attached may be collected by a fiber collector and collected by suction.

[0065] The glass composition used for the glass wool can be any known glass composition such as soda-lime glass, E glass, C glass, S glass, D glass, NE glass, ECR glass, ECT glass, quartz glass, or glass with an alkali-resistant composition, and these compositions may also be added with soda ash, borax, or the like to adjust the viscosity. Furthermore, the glass raw material may not only be a mineral raw material, but also bottle glass or plate glass collected from the market, or waste glass generated during factory production, etc.

[0066] An example of the glass composition of E-glass is SiO ２ 53% by weight, Al ２ O ３ 15% by weight, CaO 21% by weight, MgO 2% by weight, B ２ O ３ 8% by weight, Na ２ O and K ２An example of the glass composition of C-glass is one containing SiO ２ 65% by weight, Al ２ O ３ 4% by weight, CaO 14% by weight, MgO 3% by weight, B ２ O ３ 6% by weight, Na ２ O and K ２ An example of the glass composition of S-glass is a glass containing SiO ２ 64% by weight, Al ２ O ３ 25% by weight, MgO 10% by weight, Na ２ O and K ２ An example of the glass composition of D-glass is one containing SiO ２ 72% by weight, Al ２ O ３ 1% by weight, CaO 1% by weight, B ２ O ３ 23% by weight, Na ２ O and K ２ An example of the glass composition of NE glass is one containing SiO ２ 54% by weight, Al ２ O ３ 14% by weight, CaO 7% by weight, MgO 2% by weight, B ２ O ３ An example of the glass composition of ECR ​​glass is one containing 22% by weight of SiO ２ 54 to 62% by weight, Al ２ O ３ 9 to 15 wt%, CaO 17 to 25 wt%, MgO 0 to 5 wt%, Na ２ O and K ２ The total content of O is 0 to 2% by weight. An example of the glass composition of ECT glass is SiO ２ 59 to 62% by weight, Al ２ O ３ 11 to 15% by weight, CaO 20 to 25% by weight, MgO 0 to 4% by weight, Na ２ O and K ２ The total O content is 0 to 1% by weight.

[0067] (Step 2) Step 2 is a step of performing a first press accompanied by heating on the glass wool to which the binder resin has been attached, to form a GW layer consisting of the binder resin and the glass wool. Heating promotes curing of the binder resin, making it possible to produce a glass wool molded product of a desired shape. The conditions for the first press accompanied by heating can be appropriately selected depending on the glass composition and the properties of the binder resin, but the following conditions may be used, for example:

[0068] The heating temperature of the first press is preferably 150 to 350°C, and more preferably 200 to 300°C. However, if the temperature exceeds 250°C, there is a risk that the phenolic resin will partially decompose. Therefore, when a phenolic resin is used as the binder resin, the heating temperature is preferably 250°C or less or 230°C or less. The heating temperature of the first press may be within a range between any two of the following values: 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, and 350°C (including any value between these values ​​in 1°C increments). The pressing pressure of the first press is preferably 0.005 to 1.5 MPa, more preferably 0.02 to 1.25 MPa, even more preferably 0.05 to 1 MPa, and particularly preferably 0.07 to 0.8 MPa. From the viewpoint of improving cushioning properties, the pressing pressure can also be 0.1 MPa or more, 0.2 MPa or more, 0.3 MPa or more, 0.4 MPa or more, or 0.5 MPa or more. The pressing pressure of the first press may be within a range between any two of the following values: 0.005, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, and 1.5 MPa (including any value therebetween in increments of 0.01 MPa). For example, the above heating temperature and pressing pressure can also be applied when a phenolic resin is used as the binder resin and the first press is performed without using a spacer.

[0069] The first pressing time may be 10 to 3600 seconds, preferably 20 to 1200 seconds, and more preferably 30 to 800 seconds.

[0070] Furthermore, during the first pressing, one or more materials selected from woven fabric, nonwoven fabric, paper, resin film, and metal foil may be laminated on the glass wool to which the binder resin has been attached, thereby obtaining a GW layer coated with one or more materials selected from woven fabric, nonwoven fabric, paper, resin film, and metal foil.

[0071] In this process of forming the GW layer, a second press may be performed after the first press accompanied by heating to form the GW layer. By performing the second press, the difference between the compressibility C1 (%) under a load of 0.5 MPa and the compressibility C2 (%) under unloading at a load of 0.5 MPa can be reduced in the compressibility-pressure displacement curve of the GW layer.

[0072] The pressing pressure of the second press is preferably higher than the pressing pressure of the first press, and specifically may be 0.1 to 50 MPa, 0.5 to 30 MPa, or 1.0 to 20 MPa. Unlike the first press, the second press does not necessarily require heating, but may be performed with heating or cooling as needed. The second press is preferably performed at a temperature of 100°C or less, more preferably 50°C or less, and even more preferably at room temperature (10°C to 35°C). This allows pressing to be performed at short intervals without the need for heating or heat transfer. The pressing pressure of the second press may be within a range between any two of the following numbers: 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50 MPa (including any value in increments of 0.1 MPa between these values).

[0073] After heating in the first press, the second press may be performed immediately without cooling, or the second press may be performed after natural cooling. The natural cooling may be performed by waiting until the material is cooled to room temperature, or the second press may be performed without waiting until the material is cooled to room temperature. Furthermore, the second press may be performed by heating the material to a temperature lower than that of the first press. Furthermore, similar to the first press, the second press may be performed to bond one or more materials selected from nonwoven fabric, paper, resin film, and metal foil.

[0074] The time for the second pressing may be 0.01 to 360 seconds, preferably 0.1 to 100 seconds, and more preferably 0.2 to 10 seconds.

[0075] When a thermosetting resin such as a phenolic resin is used as the binder resin, the binder resin can be thermally cured by the heat generated during the first press. Furthermore, because the GW layer is obtained by pressing the glass wool and binder resin together, the manufacturing method for the battery cell spacer 10 can be simplified compared to conventional battery cell spacers that use silicone rubber.

[0076] The first press and the second press may be performed using a predetermined mold. The mold is not particularly limited, but if it is desired to impart an uneven shape to the surface of the GW layer, a mold having an uneven shape corresponding to this may be used. Furthermore, when performing the first press and the second press, a metal spacer or the like may be used to make the glass wool molded product have a predetermined thickness, or the thickness of the glass wool molded product may be adjusted by adjusting the pressing pressure without using a spacer.

[0077] In step 2, the surface of the glass wool to which the binder resin is attached may be covered with one or more materials selected from woven fabric, nonwoven fabric, paper, resin film, and metal foil, and then the first and second presses may be performed. Alternatively, a woven fabric, nonwoven fabric, or paper may be pre-impregnated with a portion of the uncured binder resin. This reduces the fluffing of the glass wool on the surface of the resulting GW layer, improving the appearance and ease of handling.

[0078] The battery cell spacer 10 can be manufactured through the above steps.

[0079] <Battery module 20> The battery module 20 obtains a desired voltage and energy capacity by connecting multiple battery cells in series or parallel. The battery module 20 of this embodiment uses the battery cell spacer 10 described above, which provides good flame retardancy and compressive elastic modulus, thereby improving the safety and reliability of the battery module 20 (see FIGS. 1 and 2 ).

[0080] 1 shows an example of a battery module 20 in which four approximately rectangular parallelepiped lithium secondary battery cells 11 are arranged in the thickness direction with battery cell spacers 10 interposed between them. However, the shape, arrangement, number, etc. of the lithium secondary battery cells 11 are not limited to this. Furthermore, the position of the battery cell spacers 10 is not limited to this.

[0081] 2 also shows an example of a battery module 21 in which a plurality of cylindrical lithium secondary battery cells 12 are arranged in parallel in the axial direction, with battery cell spacers 10 interposed between the rows. Specifically, the battery module 21 shows three rows in which five lithium secondary battery cells 12 are arranged in parallel in the axial direction, with battery cell spacers 10 interposed between the rows. Note that while FIG. 2 shows an example in which the lithium secondary battery cells 12 are arranged in a lattice pattern when viewed from above, adjacent rows may also be arranged in an offset (staggered) manner. The position of the battery cell spacers 10 is also not limited to this.

[0082] (Lithium secondary battery cell 11) The lithium secondary battery cell 11 of this embodiment is the smallest unit that functions as a battery by itself, i.e., a battery cell, and known lithium secondary battery cells can be used. The arrangement of the lithium secondary battery cells 11 can be changed as appropriate depending on the number of lithium secondary battery cells 11, etc., but from the standpoint of versatility and efficiency, it is preferable that the lithium secondary battery cells 11 are arranged in the thickness direction (stacked). The shape of the lithium secondary battery cells 11 is not particularly limited, and examples include prismatic cells, cylindrical cells, and laminated cells. However, prismatic cells are preferred from the standpoint of arranging the lithium secondary battery cells 11 at a high density, and cylindrical cells may also be used from the standpoint of versatility, durability, etc.

[0083] [Applications] The battery module 20 of the present embodiment is suitable for applications requiring high safety and reliability, etc. Examples include power tools, electric vehicles, electric two-wheeled vehicles such as electric bicycles and electric scooters, and various electric carts.

[0084] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations can also be adopted.

[0085] Hereinafter, embodiments of the present disclosure will be described in detail with reference to examples, but the embodiments of the present disclosure are not limited to these examples.

[0086] <First Experiment (First Invention)> (1) Preparation of Spacer for Battery Cell <Example 1A> A phenolic resin-coated glass wool (average fiber diameter: 7 μm, basis weight: 800 g / m) manufactured by Central Glass Fiber Co., Ltd. was used. ２ The glass wool raw material (a phenolic resin ratio: 14 wt%) was cut into 160 mm square pieces. The cut glass wool raw material was pressed at 0.31 MPa for 90 seconds using a manual hydraulic press manufactured by Imoto Machinery Works, with the upper and lower flat press plates set at a temperature of 250°C, to obtain a glass wool press-molded product (a spacer for a battery cell).

[0087] Examples 2A to 29A Glass wool press-molded products (battery cell spacers) were obtained in the same manner as in Example 1A above, except that glass wool raw cotton with phenolic resin manufactured by Central Glass Fiber Co., Ltd. was used, glass wool raw cotton having the average fiber diameter, phenolic resin ratio, and basis weight shown in Table 1 was appropriately selected, and the first pressing conditions were appropriately changed to the conditions shown in Table 1.

[0088] Examples 30A to 37A: Glass wool press-molded products (battery cell spacers) were obtained by two-stage pressing. Specifically, using a manual hydraulic press manufactured by Imoto Machinery Works, the temperatures of the upper and lower flat press plates were set to the first pressing condition shown in Table 2, pressing was performed for a predetermined time, and then the temperature of the upper and lower flat press plates was set to 25°C to achieve the second pressing condition, and pressing was performed for a predetermined time, yielding glass wool press-molded products (battery cell spacers).

[0089] (2) Measurement of Battery Cell Spacer The following measurements were carried out using the obtained glass wool press-molded product.

[0090] (Characteristics: Compression Rate Difference) A cylindrical SUS jig with a diameter of 28 mm and a height of 25 mm was attached to an Orientec Co., Ltd. universal testing machine, Tensilon RTC-2410, to perform a compression test on a glass wool press-molded product. After applying a load up to a surface pressure of 1.5 MPa, the load displacement (surface pressure / compression rate) of the glass wool press-molded product when the load was removed was measured. From the obtained load displacement, the compression rate C1 (%) when loaded at a surface pressure of 0.5 MPa, the compression rate C2 (%) when unloaded at a surface pressure of 0.5 MPa, and the difference between them were calculated. The results are shown in Tables 1 and 2.

[0091] (Compressive modulus (MPa)) A cylindrical SUS jig with a diameter of 28 mm and a height of 25 mm was attached to a universal material testing machine, Tensilon RTC-2410, manufactured by Orientec Co., Ltd., and a compression test was performed on the glass wool press-molded product to obtain a compression rate-contact pressure displacement curve. The compressive modulus (MPa) was calculated from the slope of the obtained compression rate-contact pressure displacement curve at a contact pressure of 1 MPa. The results are shown in Tables 1 and 2.

[0092] (Volume ratio of glass wool (%)) When glass wool was manufactured, the glass material was pumped out of the kiln and cooled to prepare a measurement sample. The density of the cooled measurement sample was measured using the Archimedes method. The glass density was found to be 2545 kg / m ３ Separately, the glass wool press-molded product was heated to remove the binder resin, and the weight of the glass wool press-molded product minus the binder resin was calculated using the glass density of the glass wool: 2545 kg / m ３ The volume of the glass wool was calculated from the above. The volume of the glass wool relative to the volume of the glass wool press-molded product was calculated as a percentage, which was taken as the volume ratio (%) of the glass wool. The results are shown in Tables 1 and 2. In this example, the porosity was determined by measuring the shape (length, width, thickness) of the glass wool press-molded product, and subtracting the volume ratio (%) of the glass wool from the 100 volume % determined from the shape.

[0093] (3) Evaluation of Battery Cell Spacers A cylindrical SUS jig with a diameter of 28 mm and a height of 25 mm was attached to a universal material testing machine, Tensilon "RTC-2410," manufactured by Orientec Co., Ltd., and the flat surface of the jig (the bottom surface of the cylinder, the indenter) was pressed against a glass wool press-molded product to perform a compression test. After that, the glass wool press-molded product was visually observed for traces of the indenter from the testing machine, and evaluated according to the following evaluation criteria. (Evaluation criteria) D: After the compression test, the indenter trace was clearly observed. (The depth of the indenter trace was 1.0 mm or more.) C: After the compression test, the indenter trace was observed. (The depth of the indenter trace was 0.5 mm or more and less than 1.0 mm.) B: After the compression test, the indenter trace was only slightly observed. (The depth of the indenter trace was less than 0.5 mm.) A: After the compression test, no indenter trace was observed at all.

[0094]

[0095]

[0096] <Second Experiment (Second Invention)> (1) Preparation of Cell Spacer for Battery <Example 1B> A glass wool raw cotton with phenolic resin (average fiber diameter: 7 μm, basis weight: 800 g / m) made by Central Glass Fiber was used. ２(phenolic resin ratio: 14 wt%) was cut into 140 mm square pieces. Then, the upper and lower flat press plates of an Imoto Machinery Co., Ltd. manual hydraulic press were both set to 250°C, and three sheets of the cut glass wool raw cotton were stacked and pressed at 0.077 MPa for 90 seconds to obtain a glass wool press-molded product (GW layer) having a thickness of 3.1 to 3.8 mm (average 3.4 mm).

[0097] Examples 2B to 3B Glass wool press-molded products (GW layers) were obtained using the same materials and under the same conditions as in Example 1B, except that the pressing pressure was changed from 0.077 MPa to the pressure shown in Table 3 and the thickness was set to the thickness shown in Table 3.

[0098] Example 4B Three sheets of the glass wool press-molded product obtained in Example 1B were stacked to obtain a GW layer having a thickness of 10.3 mm. Although the thermal conductivity of the GW layer of Example 4B was not measured as described below, it is considered to be close to that of Example 1B.

[0099] (2) Measurement and Evaluation of Battery Cell Spacer The following measurements and evaluations were carried out using the obtained glass wool press-molded product.

[0100] (Characteristics; Condition a) A cylindrical SUS jig measuring 28 mm in diameter and 25 mm in height was attached to a Tensilon RTC-2410 universal testing machine manufactured by Orientec Co., Ltd., and the load-displacement (contact pressure / compression rate) curve of the glass wool press-molded product was measured. The load-displacement curves of Examples 1B to 4B are shown in Figures 3 to 6, respectively. From the obtained load-displacement curves, P25 / P10 was calculated, where P10 (MPa) is the contact pressure at a compression rate of 10% and P25 (MPa) is the contact pressure at a compression rate of 25%. The compression rate (%) at a contact pressure of 0.5 MPa was also calculated. The results are shown in Table 3.

[0101] (Thermal conductivity (W / m·K)) The obtained glass wool press-molded article was added to prepare a 200 mm square sample. The thermal conductivity (W / m·K) at 25°C was measured in the surface direction of the 200 mm square sample using a thermal conductivity measuring device HC-074 / 200 manufactured by Eiko Seiki Co., Ltd. The results are shown in Table 3. A slight pressure was applied so that the hot plate and the test piece were in close contact, but essentially no pressure was applied.

[0102] (Compressive modulus (MPa)) A cylindrical SUS jig with a diameter of 28 mm and a height of 25 mm was attached to a universal testing machine Tensilon RTC-2410 manufactured by Orientec Co., Ltd., and a compression test was performed on the glass wool press-molded product to obtain a compression ratio-contact pressure displacement curve. From the obtained compression ratio-contact pressure displacement curve, the compressive modulus (MPa) was calculated from the slope at a contact pressure of 1 MPa. The results are shown in Table 3. Furthermore, for the glass wool molded product of Example 2B, a repeat test was also performed in which the above compression test was repeated five times.

[0103] (Volume ratio of glass wool (%)) When a measurement sample was taken out of the kiln during glass wool production and cooled, the density was measured using the Archimedes method. The glass density was 2545 kg / m ３ Separately, the glass wool molded product was heated to remove the binder resin, and the weight of the glass wool molded product minus the binder resin was calculated using the glass density of the glass wool: 2545 kg / m ３ The volume of the glass wool was calculated from the above. The volume of the glass wool relative to the volume of the glass wool molded product was calculated as a percentage, which was taken as the volume ratio (%) of the glass wool. The results are shown in Table 3.

[0104]

[0105] Furthermore, when the glass wool molded product of Example 2B was repeatedly subjected to a compression test five times, the same load-displacement curve was obtained from the first to fifth tests. The compression rate at a surface pressure of 0.5 MPa in the fifth test was 50% or more of the compression rate at a surface pressure of 0.5 MPa in the first test.

[0106] <Third Experiment> (1) Fabrication of Spacer for Battery Cell <Example 1C> A phenolic resin-coated glass wool (average fiber diameter: 7 μm, basis weight: 800 g / m) manufactured by Central Glass Fiber Co., Ltd. was used. ２ phenolic resin ratio: 14 wt%) was mixed with phenolic resin-coated glass wool (average fiber diameter: 7 μm, basis weight: 2400 g / m) manufactured by Central Glass Fiber Co., Ltd. ２A glass wool press-molded product (battery cell spacer) was obtained in the same manner as in Example 13A, except that the phenol resin ratio was 14 wt % and the thickness of the battery cell spacer was 4.6 mm.

[0107] Example 2C A glass wool press-molded product (battery cell spacer) was obtained in the same manner as in Example 30A.

[0108] Example 3C A glass wool press-molded product (battery cell spacer) was obtained in the same manner as in Example 27A, except that the press pressure in Example 27A was changed from 0.059 MPa to 0.016 MPa and the press time was changed from 90 seconds to 180 seconds.

[0109] (2) Measurement of Battery Cell Spacer The following measurements were carried out using the obtained battery cell spacer.

[0110] (Thermal Conductivity) The thermal conductivity of the battery cell spacer at high temperatures was measured in accordance with JIS A 1412-2:1999 Appendix A. Specifically, using a manual hydraulic pressure press manufactured by Imoto Machinery Works, an aluminum plate, a thermocouple, a reference plate (float plate glass; thickness 19 mm, thermal conductivity 0.9 W / (m·K)), a thermocouple, a battery cell spacer, a thermocouple, and an aluminum plate were stacked in this order on the lower plate of the press, and then sandwiched between the upper plate and the aluminum plate. A pressure of 20 kPa was applied to measure the temperature (to ensure reliable contact between the press surface and the glass wool; given the resilience of the glass wool, it is believed that the thermal conductivity remains almost unchanged compared to when no pressure was applied), and the average temperature of the upper and lower plates was used as the measurement temperature. That is, a measurement temperature of 80°C means 110°C for the upper plate and 50°C for the lower plate, 200°C means 230°C for the upper plate and 170°C for the lower plate, and 300°C means 330°C for the upper plate and 270°C for the lower plate. The surface temperatures of the battery cell spacer and reference plate were then monitored until a steady state was reached, and the steady state was defined as the point at which the temperature change of each thermocouple over 10 minutes was within 0.1°C. When the steady state was reached, the temperature of each thermocouple, the thermal conductivity of the reference plate, the thickness of the reference plate, and the thickness of the battery cell spacer were measured, and the thermal conductivity of the battery cell spacer was calculated using the following equation.

[0111] λ １ = λ ２× (d １ / d ２ ) × (ΔT ２ ×ΔT １ ) λ １ λ: Thermal conductivity of battery cell spacer (W / (m·K)) ２ : Thermal conductivity of the reference plate (W / (m K)) d １ d: Thickness of battery cell spacer (m) ２ : Thickness of reference plate (m) ΔT １ : Temperature difference between both sides of the battery cell spacer (K) ΔT ２ : Temperature difference between both sides of the reference plate (K)

[0112] Furthermore, because glass wool is made up of a large amount of air, its heat transfer pattern is greatly affected by the air present between the glass fibers. The thermal conductivity of the air in glass wool increases as the temperature rises, but as the volume fraction of glass wool increases, air convection is suppressed, preventing an increase in thermal conductivity even at high temperatures.

[0113]

[0114] This application claims priority based on Japanese Patent Application No. 2024-130671 filed on August 7, 2024, and Japanese Patent Application No. 2025-009185 filed on January 22, 2025, the disclosures of which are incorporated herein in their entireties.

[0115] REFERENCE SIGNS LIST 10 Battery cell spacer 11 Lithium secondary battery cell 12 Lithium secondary battery cell 20 Battery module 21 Battery module

Claims

1. A battery cell spacer used in a battery module comprising a plurality of lithium secondary battery cells and a battery cell spacer interposed between adjacent lithium secondary battery cells, wherein the battery cell spacer has a GW layer containing a binder resin and glass wool, and in the compression rate-contact pressure displacement curve of the GW layer, the difference between the compression rate C1 (%) when loaded at a contact pressure of 0.5 MPa and the compression rate C2 (%) when unloaded at a contact pressure of 0.5 MPa is 20% or less.

2. A battery cell spacer according to claim 1, wherein the volume fraction of the glass wool in the GW layer is 1 to 30% and the thickness is 1 to 20 mm.

3. A battery cell spacer according to claim 1 or 2, wherein the average fiber diameter of the glass wool is 3 to 20 μm.

4. A battery cell spacer according to claim 1 or 2, wherein the mass ratio of the binder resin to the glass wool is 20 mass % or less.

5. A battery cell spacer used in a battery module comprising a plurality of lithium secondary battery cells and a battery cell spacer interposed between adjacent lithium secondary battery cells, wherein the battery cell spacer has a GW layer containing a binder resin and glass wool, the GW layer has a volume fraction of the glass wool of 1 to 30% and a thickness of 1 to 20 mm, the average fiber diameter of the glass wool is 3 to 20 μm, and the mass ratio of the binder resin to the glass wool is 3 to 40% by mass.

6. A battery cell spacer according to claim 5, wherein the volume ratio of the glass wool in the GW layer is 8 to 30%.

7. A battery cell spacer according to claim 1 or 5, wherein the thermal conductivity of the GW layer in the stacking direction at 25°C is 0.025 to 0.050 W / m·K.

8. A battery cell spacer according to claim 1 or 5, wherein the compressive elastic modulus of the GW layer at a surface pressure of 1 MPa under load, calculated from the slope of the GW layer's compressibility-surface pressure displacement curve at 1 MPa, is 2 to 30 MPa.

9. A battery cell spacer according to claim 1 or 5, wherein the GW layer satisfies the following condition a: (Condition a) In the compression rate vs. surface pressure displacement curve of the GW layer, when the surface pressure at a compression rate of 10% is P10 (MPa) and the surface pressure at a compression rate of 25% is P25 (MPa), P25 / P10 is 1 or more and 50 or less.

10. A battery cell spacer according to claim 1 or 5, wherein the binder resin comprises one or more selected from the group consisting of phenolic resin, urea resin, acrylic resin, sugar-based binder, polyvinyl alcohol-based resin, and polyethylene glycol-based resin.

11. A battery cell spacer according to claim 1 or 5, wherein at least a portion of the GW layer is covered with one or more materials selected from woven fabric, nonwoven fabric, paper, resin film, and metal foil.

12. A battery module comprising the battery cell spacer according to claim 1 or 5.

13. A method for manufacturing a battery cell spacer used in a battery module comprising a plurality of lithium secondary battery cells and a battery cell spacer interposed between adjacent lithium secondary battery cells, the method comprising the step of performing a first press accompanied by heating on glass wool to which a binder resin has been attached, to form a GW layer containing the binder resin and the glass wool.

14. A method for manufacturing a battery cell spacer according to claim 13, wherein the first pressing is carried out at 150 to 350°C and 0.005 to 1.5 MPa.

15. A method for manufacturing a battery cell spacer according to claim 13 or 14, further comprising the step of adhering a binder resin to glass wool before the step of forming the GW layer.

16. A method for manufacturing a battery cell spacer as set forth in claim 13 or 14, wherein the binder resin contains one or more types selected from the group consisting of phenol resin, urea resin, acrylic resin, sugar-based binder, polyvinyl alcohol-based resin, and polyethylene glycol-based resin.

17. The method for manufacturing a battery cell spacer according to claim 13 or 14, wherein the glass wool to which the binder resin is attached has a basis weight of 500 to 5,000 g / m ２ This is a method for manufacturing a spacer for a battery cell.

18. A method for manufacturing a battery cell spacer according to claim 13 or 14, wherein the mass ratio of the binder resin to the glass wool is 20 mass % or less.

19. A method for manufacturing a battery cell spacer according to claim 13 or 14, wherein a second press is further performed after the first press to form the GW layer.

20. A method for manufacturing a battery cell spacer according to claim 19, wherein the second pressing is carried out at 100°C or less.

21. A method for manufacturing a battery cell spacer according to claim 19, wherein the pressing pressure of the second press is higher than the pressing pressure of the first press.

22. A method for manufacturing a battery cell spacer according to claim 19, wherein the pressing pressure of the second press is 0.1 to 50 MPa.

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