Battery pack

Abstract

This battery pack is formed by stacking a plurality of cells and a partitioning member for partitioning the cells from each other. The partitioning member has a heat insulation part. The heat insulation part has a compressive elastic modulus of 0.5-10 MPa in the stacking direction. The heat insulation part has a non-contact region at which none of the cells are in contact with the insulation part.　It is possible to provide a battery pack which can maintain the safety of cells by preventing the cells adjacent to each other from coming into contact with each other due to expansion of the cells.

Description

Technical Field

[0001] The present invention relates to a battery pack.

Background Art

[0002] Conventionally, regarding a battery module including a secondary battery (hereinafter also referred to as a single battery) mounted on a moving body such as a vehicle or a ship, various members may be arranged between the single batteries for various purposes.

[0003] For example, in Patent Document 1, a secondary battery module in which a buffer plate is arranged between single batteries is disclosed in order to allow the expansion of the single battery and appropriately maintain the surface pressure applied to each single battery. Further, in Patent Document 2, a battery pack in which a heat conduction member having a high flexural modulus of elasticity as a base material is arranged between single battery cells is disclosed in order to suppress heat transfer to adjacent single battery cells and efficiently radiate heat to a heat dissipation space.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] In both Patent Document 1 and Patent Document 2, in order to exhibit the respective functions of the buffer plate and the heat conduction member, they are arranged in contact with each single battery.

[0006] Incidentally, since the multiple individual cells that make up a battery pack are arranged in the thickness direction and placed in the housing under pressure in the thickness direction, pressure is also applied to the components sandwiched between the individual cells. Furthermore, it is known that individual cells expand when charged or when they become hot. In this case, further pressure is applied to the components sandwiched between the individual cells. That is, as in Patent Documents 1 and 2, if the components are provided in contact with each individual cell, there is a concern that the components may deform or break due to the expansion pressure of the individual cells caused by charging and high temperatures during the use of the battery pack. And if an individual cell generates heat in such a state, the heat is more easily transferred to the surrounding cells, and there is a high possibility that the safety of the battery pack cannot be maintained.

[0007] Furthermore, Patent Document 3 discloses a technique for stacking multiple battery cells by combining a support portion with an expansion portion having a larger coefficient of thermal expansion than the support portion. In this technique, when an abnormality occurs and the expansion portion expands, the pressure between the stacked individual cells increases. Therefore, in order to constrain and maintain the shape of the entire battery stack, the battery module housing needs to be made stronger, which has the drawback of increasing the weight of the battery stack.

[0008] The present invention has been made in view of the above-mentioned problems, and aims to provide a battery pack that can maintain the safety of the battery by preventing adjacent cells from coming into contact due to the expansion of individual cells. [Means for solving the problem]

[0009] The inventors of the present invention have diligently studied to solve the above problems and have found that the above problems can be solved by providing a partition member with an insulating portion between each stacked cell, wherein the partition member has an insulating portion having a specific compressive modulus in the stacking direction, and further by providing a non-contact area where the partition member and the cell opposite it do not come into contact with each other. Based on this, the present invention has been completed as follows. That is, the present invention is as follows.

[0010] [1] A battery pack comprising a plurality of single cells stacked together, wherein at least one of the single cells has a partition member, the partition member has a heat insulating portion, the compressive modulus of the heat insulating portion in the single cell stacking direction is 0.5 to 10 MPa, and the partition member has a non-contact region that does not come into contact with the single cell. [2] The battery pack according to [1] above, wherein the partition member is located between each cell. [3] The battery pack according to [1] or [2] above, wherein the partition member is provided with a support portion on the outside of the heat insulating portion in a planar direction perpendicular to the stacking direction of the single cells, and the support portion is in contact with the single cell. [4] The battery pack according to [3] above, wherein the compressive modulus of the support portion in the single-cell stacking direction is 0.5 to 100 MPa. [5] A battery pack according to any one of [1] to [4] above, wherein the distance between the non-contact area and the single cell on the non-contact area is 0.1 to 2.5 mm. [6] Area of ​​the heat insulating part when viewed from above (S I ) with respect to the area of ​​the non-contact region (S N ) proportion (S N / S I A battery pack as described in any of the above [1] to [5], wherein the ratio is 0.3 to 1. [7] Area of ​​the partition member when viewed from above (S P ) with respect to the area of ​​the support portion (S S ) proportion (S S / S P A battery pack as described in any of the above [3] to [6], wherein the ratio is 0.02 to 0.2. [8] The battery pack according to any one of [1] to [7] above, wherein the partition member when viewed from above is rectangular, and the support portion on the partition member is linear and forms at least one pair of opposite sides. [9] A battery pack according to any of [1] to [8] above, wherein the heat insulating portion holds a liquid.

[10] The battery pack according to [9] above, wherein the heat insulating portion is a porous heat insulating material and the liquid is held in the porous heat insulating material.

[11] The battery pack according to any one of [1] to

[10] above, wherein the heat insulating part is housed in an outer casing.

[12] The battery pack according to

[11] above, wherein the outer casing is a laminate comprising a metal foil and a thermoplastic resin layer.

[13] The battery pack according to

[12] above, wherein the metal constituting the metal foil is at least one of aluminum, copper, tin, nickel, stainless steel, lead, tin-lead alloy, bronze, silver, iridium, and phosphor bronze.

[14] A method for manufacturing a battery pack comprising a plurality of single cells stacked together, wherein a partition member is placed between at least one of the single cells, the partition member has a heat insulating portion, the compressive modulus of the heat insulating portion in the single cell stacking direction is 0.5 to 10 MPa, the partition member is fixed in a state where pressure is applied in the thickness direction of the heat insulating portion, and a non-contact area is provided in which the partition member does not come into contact with the single cells. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a battery pack that can maintain the safety of the battery by preventing adjacent cells from coming into contact due to the expansion of individual cells. [Brief explanation of the drawing]

[0012] [Figure 1] This is a cross-sectional view showing an example of a battery pack according to the first embodiment. [Figure 2] This is a cross-sectional view showing an example of a battery pack according to the second embodiment. [Figure 3] This figure shows an example of a partition member; (A) is a plan view, and (B) is a cross-sectional view when cut along XX shown in (A). [Figure 4] A cross-sectional view showing an example of a battery pack according to another embodiment. [Figure 5] This is a plan view showing an example of a partition member. [Figure 6] This figure shows another example of a partition member, where (A) is a plan view and (B) is a cross-sectional view taken when cut along XX shown in (A). [Figure 7] This figure shows another example of a partition member, where (A) is a plan view and (B) is a cross-sectional view taken when cut along XX shown in (A). [Figure 8] This figure shows another example of a partition member, where (A) is a plan view and (B) is a cross-sectional view taken when cut along XX shown in (A). [Figure 9] This is a plan view showing an example of a single cell. [Figure 10] Figure 9 is a front view of a single cell. [Figure 11] Figure 9 is a side view of a single cell. [Figure 12] This figure plots the relationship between press pressure (restraining pressure) and thickness retention rate in the heat-insulating section of a partition member. [Figure 13] This figure shows an example of a battery pack when a single cell expands (an example without support parts). [Figure 14] This figure shows an example of a battery pack when a single cell expands (an example using a support). [Modes for carrying out the invention]

[0013] The present invention will be described below based on embodiments. However, the present invention is not limited to the embodiments described below. In this specification, when "X~Y" (where X and Y are any numbers) is written, unless otherwise specified, it includes the meaning of "greater than or equal to X and less than or equal to Y," as well as "preferably greater than X" or "preferably less than Y." Similarly, when "greater than or equal to X" (where X is any number) is written, unless otherwise specified, it includes the meaning of "preferably greater than X," and when "less than or equal to Y" (where Y is any number) is written, unless otherwise specified, it also includes the meaning of "preferably less than Y."

[0014] [First Embodiment] As shown in Figure 1, the battery pack 10A according to the first embodiment is made up of a plurality of individual cells 12 and partition members 14A that separate each of the individual cells 12, stacked on top of each other. The partition members 14A are provided at least between each individual cell 12 that make up the battery pack 10A, and are members that prevent each individual cell 12 from coming into contact with each other. The partition members 14A can also be used to separate individual cells 12 from other components, in addition to separating each individual cell 12 from each other. In the example shown in Figure 1, partition members 14A are stacked between each cell 12, but it is not necessary for partition members 14A to be present between all cells; it is sufficient for at least one of the cell spaces to have a partition member.

[0015] The partition member 14A has a heat insulating portion 16, and the compressive modulus of the heat insulating portion 16 in the stacking direction (Y direction) is 0.5 to 10 MPa. The partition member 14A also has a support portion 18 on the outside of the heat insulating portion 16 in the plane direction perpendicular to the stacking direction (X direction), and has a non-contact area 20 that does not come into contact with the cell 12. In the example shown in Figure 1, the non-contact area 20 is formed by the support portion 18 contacting and supporting each cell 12, but the non-contact area 20 may be formed by means other than the support portion 18. Furthermore, in this invention, it is sufficient that the non-contact area 20 is formed, and the support portion 18 or a member to replace it may not be necessary. For example, as shown in Figure 13, when assembling the cell and partition member, the heat insulating portion 16 is slightly compressed by the assembly pressure, and the end of the partition member warps upward, resulting in a non-contact area that occurs on the heat insulating portion and the partition member. Furthermore, while the insulating layer is compressed when the single cell expands, sufficient thickness is maintained to demonstrate insulating performance. Furthermore, as shown in Figure 14, even in the embodiment with a partition member, the heat insulating portion may be slightly compressed by the assembly pressure, and the end of the partition member may bend upward due to the compression of the heat insulating portion. This embodiment is preferable because the presence of a support portion makes it easy to adjust the non-contact portion, and a non-contact portion is easily generated on the heat insulating portion. Figures 13 and 14 are conceptual diagrams showing the insulated section assembled in a slightly compressed state, while the diagrams to the right of the arrows are conceptual diagrams showing the single cell expanding and the insulated section further compressed. Both are conceptual representations of the relationship between the single cell and the insulated section, and are somewhat exaggerated.

[0016] It is known that the individual cells that make up a battery pack expand with use. The inventors have found that the initial expansion pressure when a single cell expands is about 0.1 MPa, but it eventually rises to several MPa. Therefore, in this invention, the compressive modulus of the heat insulating portion 16 of the partition member 14A is set to 0.5 to 10 MPa to make it flexible and to include the above-mentioned range of expansion pressure. On the other hand, if the expansion of a single cell occurs locally (for example, in the center), localized pressure is also applied to the heat insulating portion 16 of the partition member 14A. At the point where localized pressure is applied, the flexible heat insulating portion 16 is compressed further, and sufficient heat insulation is not achieved, causing heat to be conducted to the surrounding single cells.

[0017] Therefore, in this invention, by providing a non-contact area in the battery pack where the partition member does not come into contact with the individual cells, the initial expansion of the individual cells is not restricted by the partition member and is allowed to expand somewhat freely, thus maintaining good safety in the battery pack. Furthermore, when the individual cells expand, the expansion pressure is absorbed by the flexible heat-insulating part, allowing the heat-insulating effect of the heat-insulating part 16 to be fully utilized, making it difficult for heat to be transferred to the surrounding individual cells, thus maintaining good safety in the battery pack. Another benefit of having a non-contact area in the battery pack where the partition member does not come into contact with the individual cells is that the shear force during assembly of the battery pack is distributed in the non-contact area, preventing plastic deformation of the heat insulating portion. Preferably, the battery pack has a non-contact area where the heat insulating portion of the partition member does not come into contact with the individual cells.

[0018] Here, the term "insulating portion" refers to the part that provides insulation, and is composed of an insulating material as described later. In a partition member in which the insulating portion is housed in the outer casing, in the portion where the insulating material is not covered by the outer casing, a non-contact area between the partition member and the single cell may be formed on the insulating material. Furthermore, in a partition member in which the insulating portion is housed in the outer casing, in the portion where the insulating material is covered by the outer casing, a non-contact area between the partition member and the single cell may be formed on the outer casing directly above the insulating material.

[0019] [Second Embodiment] As shown in Figure 2, the battery pack 10B according to the second embodiment consists of a plurality of individual cells 12 and partition members 14B that separate each of the individual cells 12, stacked together. The partition member 14B has an insulating portion 16 housed in an outer casing 22. As shown in Figure 3, the partition member 14B has a support portion 18 on the outer casing 22, on the outside of the insulating portion 16 in a plane direction (X direction) perpendicular to the stacking direction, and has a non-contact area 20 that does not come into contact with the individual cells 12. The non-contact area 20 is formed by the support portion 18 contacting and supporting each individual cell 12, similar to the first embodiment. The second embodiment is the same as the first embodiment except that the insulating portion 16 is housed in the outer casing 22. Because the insulating portion 16 is housed in the outer casing 22 as in the second embodiment, when the individual cells 12 become hot, the heat transfer is diffused in the direction of the outer casing surface, so that the heat locally applied to the contact area can be diffused, and the heat insulation performance can be further improved.

[0020] In both the first and second embodiments, the non-contact areas 20 of the partition members 14A and 14B are located on one side in the stacking direction, but the non-contact areas 20 may be located on both sides. For example, in Figure 2, the non-contact area 20 of the partition member 14B is located on one side in the stacking direction, but as shown in Figure 4, it may be located on both sides. In this case, each side of the outer casing 22 is provided with a support portion 18 on the outside of the heat insulating portion 16 in the plane direction (X direction) perpendicular to the stacking direction.

[0021] In this invention, as described above, the compressive modulus of the heat insulating section is set to 0.5 to 10 MPa, taking into consideration the expansion pressure of the single cell. By setting the compressive modulus of the heat insulating section to 0.5 MPa or higher, it is possible to absorb the stress caused by swelling during charging and discharging of the single cell, as well as the stress caused by expansion during deterioration over time, thereby extending the lifespan of the cell. From this viewpoint, the compressive modulus of the heat insulating section is preferably 0.8 MPa or higher, and more preferably 1 MPa or higher. Furthermore, the compressive modulus of the heat insulating section is preferably 8 MPa or lower, and more preferably 6 MPa or lower. By setting it within the above range, it is possible to prevent the heat insulating section from becoming locally thinned during swelling during charging and discharging of the single cell, as well as during expansion during deterioration over time, thereby maintaining the necessary heat insulating effect in case of abnormalities over a long period of time. Note that the elastic modulus and density of the heat insulating material are closely related; for example, if you want to lower the elastic modulus, you can reduce the density, and if you want to increase the elastic modulus, you can increase the density. The compressive modulus can be measured using the method described in the test example.

[0022] Furthermore, when the heat insulating section 16 is housed in the outer casing 22, it is preferable that the outer casing 22 does not affect the compressive modulus of the heat insulating section 16. Therefore, it is preferable that the compressive modulus, including the outer casing 22 and the heat insulating section 16, be 0.5 to 10 MPa, and the preferred range is the same as that of the compressive modulus of the heat insulating material.

[0023] Furthermore, it is preferable that a three-dimensional space is formed from the non-contact area to the single cell directly above it, and that an air layer is formed in this space. The presence of the air layer allows the initial expansion of the single cell to proceed to a certain extent throughout the entire structure. In addition, by including the non-contact area, the shear force during assembly of the battery pack is distributed in the non-contact area, preventing plastic deformation of the heat-insulating part. Although a thicker air layer is advantageous in terms of heat insulation, there are also disadvantages such as an increase in the size of foreign objects that may be caught during the assembly of the stacked battery and an increase in cost due to taking up more space. Therefore, the thickness of the air layer is preferably designed to be 0.1 to 2.5 mm, more preferably 0.2 to 1.5 mm, and even more preferably in the range of 0.2 to 1 mm, for example, as the average distance from the non-contact region to the single battery directly above it.

[0024] From the perspective of the balance of heat insulation properties between the air layer and the heat insulation part, the ratio (T A ) of the thickness (T I ) of the air layer to the thickness (T A / T I ) of the heat insulation part is preferably 0.05 to 1.0, and more preferably 0.07 to 0.8. In addition, the thickness of the heat insulation part (when covered by the exterior body, the total thickness of the heat insulation part and the exterior body) is preferably 0.5 to 3.0 mm, more preferably 0.6 to 2 mm, and particularly preferably 0.6 to 1.5 mm. By setting it within the above range, even when a plurality of single battery cells are stacked at a high density, sufficient heat insulation can be obtained during the charging and discharging expansion of the single battery cells and even during the expansion during aging deterioration, so that the heat insulation effect required during abnormal times can be maintained over a long period.

[0025] In FIG. 1, the non-contact region 20 is on the entire surface of one side of the heat insulation part 16, but the present invention is not limited to this and can be appropriately set within the range where the initial expansion can proceed substantially over the entire surface. Preferably, the non-contact region of the partition member does not include the central part of the heat insulation part.

[0026] The ratio (S I ) of the area (S N ) of the non-contact region to the area (S N / S IThe ratio is preferably 0.3 to 1. A ratio of 0.3 to 1 allows for more reliable absorption of the expansion of the single cell. From this viewpoint, the ratio is more preferably 0.5 to 1, even more preferably 0.7 to 1, and particularly preferably 0.9 to 0.95. The area of ​​the insulated section when viewed from above is 25-200 cm². 2 It is preferable that this be the case.

[0027] Area of ​​the partition member when viewed from above (S P Area of ​​the support part relative to (S S ) proportion (S S / S P ) is preferably 0.02 to 0.2. This range makes it easier to maintain a stable non-contact area. From this perspective, S S / S P It is more preferable that the value be between 0.04 and 0.15. Note that the area (S) when there are multiple support parts S ) is the sum of those.

[0028] Considering productivity and ease of handling, the shape of the partition members is preferably rectangular when viewed from above, as shown in Figures 3 and 5, with an area of ​​60 to 300 cm². 2 It is preferable that this be the case.

[0029] From the viewpoint of fully utilizing the heat insulating effect of the heat insulating section and efficiently obtaining a non-contact area, it is preferable that the heat insulating section be provided so as to cover the pressure concentration point of the single cell in contact with the partition member. Generally, it is preferable that the pressure concentration point be provided so as to cover the center when the stacked surface of the batteries is viewed in plan, that is, the center of gravity when the contact surface is viewed in plan. For example, if the stacked surface of the batteries is rectangular, it is the intersection of the diagonals, and if it is circular, it is the center. Furthermore, when using a support portion, in order to fully utilize the heat insulating effect of the heat insulating portion and efficiently obtain a non-contact area, it is preferable to avoid the central part of the heat insulating portion that covers the pressure concentration point of the single cell in contact with the partition member, and to have it located at the periphery.

[0030] Furthermore, the support portion 18 provided on the outside of the heat-insulating portion is preferably installed in a linear manner, forming opposite sides. Specifically, as shown in Figure 3, it is preferable that the support portion on the partition member is provided parallel to the vertical direction, forming a pair of opposite sides. In addition, as another configuration that forms at least a pair of opposite sides, the support portion 18 may be a rectangular shape, as shown in Figure 5. Furthermore, the support portion 18 may be covered by the outer casing 22, as shown in Figures 6 to 8. Preferably, the support portion 18 is arranged parallel to each other in the vertical direction, forming a pair of opposite sides, as shown in Figure 6. Also, as shown in Figure 7, the support portion 18 may extend to the end in the forming direction. Furthermore, as shown in Figure 8, the end of the support portion 18 in the width direction may be exposed.

[0031] The following describes the various components of the battery pack according to the present invention. [Insulation section] The thermal conductivity of the insulating material constituting the insulation section is preferably 0.3 W / (m·K) or less, and more preferably 0.1 W / (m·K) or less. The thermal conductivity of the insulating material can be determined by referring to several methods, such as the protective hot plate method described in JIS A1412-1, the heat flow meter method described in JIS A1412-2, the pulse heating method described in JIS R1611, the hot wire method described in JIS R2616, and the periodic heating method, but this does not limit the measurement method. Specifically, regarding the periodic heating method, temperature-controllable heaters are installed on the upper and lower surfaces of the test specimen (insulating material), and the upper heater applies periodic temperature fluctuations in the thickness direction, while the lower heater controls the lower surface to a constant temperature. At this time, when the temperature fluctuation propagates from the upper surface to the middle surface of the test specimen, a phase difference (time difference) occurs. The thermal diffusivity is determined from this phase difference, and the thermal conductivity is calculated from the product of the specific heat and density.

[0032] The insulating material that makes up the insulation section has a density of 0.23 to 1.1 g / cm³. 3It is preferable to use a material with the following properties. If the density of the insulating material is below the above upper limit, there will be many air layers in the internal voids, resulting in good thermal insulation, which is preferable. On the other hand, if the density of the insulating material is above the above lower limit, the amount of deformation during compression will be small, which is preferable. Therefore, from these viewpoints, the density of the insulating material is more preferably 0.25 g / cm³. 3 The above is preferable, and more preferably 0.28 g / cm³ 3 The above applies, while more preferably 1.0 g / cm³. 3 The following, and more preferably 0.90 g / cm³ 3 The following describes how to control the density of insulation materials. By reducing the amount of fibrous material through porous construction, as described later, the density can be lowered. Conversely, by increasing the amount of fibrous material, the density can be increased.

[0033] Furthermore, it is preferable for the insulating section to contain liquid in order to enhance the safety of the battery pack. Secondary batteries used as power sources for vehicles and the like are generally used as battery packs consisting of multiple individual cells (hereinafter also referred to as "cells"). However, if one of the constituent cells is damaged due to overcharging or an internal short circuit, the surface temperature of the cell may exceed several hundred degrees, and this can spread to surrounding cells, causing damage to the entire battery pack in a chain reaction. When one of the constituent cells overheats abnormally, the liquid evaporates, absorbing heat of vaporization from the surroundings and suppressing the rise in temperature. Heat can also be released as the evaporated gas escapes. When the insulating section contains liquid, it is necessary to retain the liquid inside the insulating section, so suppressing the expansion of individual cells is a particularly important issue, and the presence of an air layer is effective in mitigating the load pressure on the insulating section due to the expansion of individual cells. Furthermore, in order to retain the liquid, it is preferable that the insulating material constituting the insulating section be a porous insulating material. In other words, it is preferable that the insulating section is such that the liquid is retained within its porous insulating material.

[0034] Porous insulation materials preferably contain fibers and particles. The fibrous 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, at least one selected from glass fibers, rock wool, ceramic fibers, and biosoluble inorganic fibers is particularly preferred. 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.

[0035] Furthermore, the particles are preferably powdered inorganic materials, and are 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, with at least one selected from silica particles, alumina particles, calcium silicate, and vermiculite being particularly preferred. 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 a porous structure even when compressed and deformed, and therefore has excellent water retention properties. The clay minerals are mainly magnesium silicate (including talc and sepiolite), montmorillonite, and kaolinite.

[0036] Furthermore, the entire insulating section may be formed from the porous insulating material described above. By forming the entire insulating section from a porous material, the amount of liquid that can be held within its cavities can be increased.

[0037] The above liquid is preferably one with a boiling point of 80°C to 250°C at atmospheric pressure, and more preferably one with a boiling point of 100°C to 150°C at atmospheric pressure. In addition to water, the liquid preferably contains at least one selected from the group consisting of, for example, alcohols, esters, ethers, ketones, hydrocarbons, fluorinated compounds, and silicone oils. These can be used individually or as a mixture of two or more. The liquid may also contain additives such as antifreeze, preservatives, and pH adjusters. By providing antifreeze, damage to the outer casing due to expansion caused by freezing can be avoided. Furthermore, by adding a pH adjuster, the pH of the liquid can be changed by components leached from the powdered inorganic material, reducing the possibility of deterioration of the powdered inorganic material, the outer casing, and the liquid (water) itself. The liquid is not limited to these and can be added as needed.

[0038] [Exterior] The outer casing primarily houses the heat-insulating section in a sealed state. For example, a film or sheet made of resin and / or metal can be used as the outer casing, and a laminate of metal and resin can also be used. Using such a laminate of metal and resin to house the heat-insulating section is particularly preferable for obtaining high heat resistance and strength. As the laminate having the above-mentioned metal-resin laminated structure, it is preferable to use a laminate containing a metal foil and a thermoplastic resin layer, and a laminate of three or more layers containing a resin layer, metal foil, and a resin sealant layer.

[0039] The metal constituting the metal foil is preferably at least one of aluminum, copper, tin, nickel, stainless steel, lead, tin-lead alloy, bronze, silver, iridium, and phosphor bronze. Specifically, these include aluminum foil, copper foil, tin foil, nickel foil, stainless steel foil, lead foil, tin-lead alloy foil, bronze foil, silver foil, iridium foil, and phosphor bronze foil. In particular, aluminum foil, copper foil, and nickel foil are preferred, and aluminum foil is even more preferred. It is preferable that at least one of the metals listed above is selected.

[0040] Furthermore, at least one of thermosetting resins and thermoplastic resins can be used as the resin, but the use of thermoplastic resins is preferred. Examples of resins include polyethylene, polypropylene and other olefin resins, polystyrene, nylon, acrylic resins, epoxy resins, polyurethane, polyether ether ketone, polyethylene terephthalate, polyphenylene sulfide, polycarbonate, and aramid. At least one selected from polypropylene, nylon, and polyethylene terephthalate is particularly preferred.

[0041] The thickness of the outer casing is not particularly limited, but is preferably, for example, 5 μm to 200 μm. If the outer casing is a laminate, it is preferable within the above range that the metal foil is 3 μm to 50 μm thick and the resin layer is 2 μm to 150 μm thick. This allows the metal foil to exhibit heat resistance and low water vapor permeability, while the resin improves the sealing performance.

[0042] Furthermore, to house the heat insulating portion within the outer casing, for example, the peripheral edges of two outer casing sheets can be joined in a ring shape by heat fusion or adhesive, and then the heat insulating portion can be sealed inside the outer casing; or, one outer casing can be folded and its peripheral edges joined by heat fusion or adhesive, and the heat insulating portion can be sealed. The outer casing preferably has flexibility (elasticity).

[0043] [Support part] The support portion is a component that can be preferably used to maintain a non-contact area 20 in the assembled battery pack where the individual cells and the heat insulating portion of the partition member do not come into contact. If the support portion is not used, a non-contact area can be obtained, for example, by providing a holding component to hold the partition member in the battery pack housing, or by adjusting the thickness of the heat insulating portion. Methods for using the support portion as a partition member include, for example, adhering it to any position on the heat insulating portion, adhering it together with the heat insulating portion on the individual cells constituting the battery pack, providing it on packaging material that houses the heat insulating portion in an outer casing, or housing the heat insulating portion in an outer casing with the support portion positioned around its periphery.

[0044] The compressive modulus of the support portion in the lamination direction is preferably 0.5 to 100 MPa, more preferably 1 to 50 MPa, even more preferably 2 to 50 MPa, and particularly preferably 3 to 25 MPa, as this allows for control of the thickness relative to the restraining force during assembly.

[0045] Thickness of the support part (T S The thickness of the insulation section (T) is preferably 0.8 to 3.5 mm, and more preferably 1.0 to 3.2 mm. I ) Thickness of the support part (T S ) ratio (T S / T I From the viewpoint of maintaining a good air layer, the value is preferably 1.0 to 2.2, and more preferably 1.1 to 2.0.

[0046] The density of the partitioning material is set at 0.3-2 g / cm³, considering the need to maintain thermal insulation between individual cell cells while avoiding an excessive increase in the overall weight of the battery pack. 3 Preferably, it is 0.4 to 1.5 g / cm³. 3 It is preferable that it be so.

[0047] [Single cell] The single cell is preferably a lithium-ion secondary battery comprising, for example, 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. Figure 9 is a plan view showing an example of a single cell 12 that makes up a battery pack, Figure 10 is a front view of the single cell 12 shown in Figure 9, and Figure 11 is a right side view of the single cell 12. The single cell 12 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.

[0048] The area ratio of the partition member to the single cell to which the partition member is applied (partition member area / single cell area) is preferably 0.8 or more. When this area ratio is 0.8 or more, short circuits due to contact between single cells become less likely. In addition, the pressure applied to the surface of the single cells does not become uneven, and the distortion of the electrodes inside the single cells does not become large, which is less likely to cause performance degradation over time. From the above viewpoint, the area ratio is more preferably 0.9 or more, and even more preferably 0.95 or more. Furthermore, from the viewpoint that the battery module housing will become larger and the overall battery energy density of the module will decrease, it is preferably 1.2 or less, more preferably 1.1 or less, and even more preferably 1.05 or less.

[0049] [Battery pack] The present invention provides a partition member between at least one single cell constituting a battery pack. It can also be used to partition a single cell constituting the battery pack from other components. Preferably, the partition member of the present invention is provided between all single cells constituting the battery pack. A known method can be used to assemble the battery pack. For example, a method can be used in which multiple single cells are arranged in a row, and the partition member of the present invention is placed between at least one of each single cell, or between a single cell and a component other than the single cell, and the partition member is fixed in place while applying pressure of, for example, 1 to 5 kN in the thickness direction of the heat insulating portion of the partition member. Furthermore, it is also possible to attach any other component such as a tray. The above is just one example, and the method of applying the partition member of the present invention to a battery pack is not limited to this example.

[0050] The battery pack according to this embodiment, as described above, is applicable to battery packs installed 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 (UPSs), 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 aforementioned EVs. [Examples]

[0051] (Evaluation method) Evaluation Method 1 (Test Result 1) We assume that multiple individual cells constituting a battery pack are arranged in the thickness direction, with partition members equipped with insulating sections between each cell, and that the battery pack is housed in a casing under pressure in the thickness direction. In this case, the restraining pressure applied in the thickness direction to maintain the structure of multiple individual cells including the partition members is defined as the design pressure, and this pressure is set to 2 MPa. Next, we assume that each individual cell will swell during charging and high temperatures when the battery pack is in use. We calculate the pressure on the partition members based on the amount of swelling (mm) of each individual cell. When the pressure on the partition members exceeds the design pressure, the structure of multiple individual cells cannot be maintained, or pressure load is placed on the individual cells, causing deformation or destruction of the cells, resulting in a dangerous situation. Therefore, we evaluated the amount of swelling (mm) of the individual cells when the pressure on the partition members exceeds the design pressure based on the following criteria. Evaluation Criteria ○: Single cell swelling of 0.5 mm or more △: Cellular cell swelling of 0.4mm or more, but less than 0.5mm. ×: Single cell swelling is less than 0.4 mm The results are shown in Table 1 below.

[0052] Evaluation Method 2 (Test Result 2) The thermal insulation performance during single-cell expansion was evaluated based on the following criteria. Evaluation Criteria ○: When a pressure of 2 MPa was applied to the insulation section, more than 50% of the initial thickness of the insulation material was retained. △: When a pressure of 2 MPa was applied to the insulation, the insulation material retained more than 30% but less than 50% of its initial thickness. ×: When a pressure of 2 MPa was applied to the insulation, the thickness was less than 30% of the initial thickness of the insulation material.

[0053] (Compression modulus) The compressive modulus (23°C) of the heat-insulating portion of the partition member was measured in accordance with JIS K7181. Specifically, the partition member was placed in a hydraulic press and the press pressure and displacement during compression were recorded. From these results, the compressive stress and compressive strain were determined, and the compressive modulus was calculated by dividing the difference in compressive stress by the difference in compressive strain. Figure 12 shows the relationship between the press pressure (restraining pressure) and the thickness retention rate in the heat-insulating portion of the partition member. The compressive modulus was determined in the region where the press pressure (restraining pressure) and the thickness retention rate have a linear relationship after the start of compression.

[0054] (Test Example 1) A porous sheet (vermiculite sheet, 120mm long, 60mm wide, 0.9mm thick, compression modulus 1.3MPa) is used as insulation, and an aluminum laminate film (polyethylene terephthalate as the resin layer (outside of the partition member), polyethylene (inside of the partition member)) is used as the exterior body. The packaging material was placed inside a 0.11mm thick container and sealed by sealing the edges of all four sides of the outer casing using a vacuum degassing sealer (Fuji Impulse Co., Ltd., model number: FCB-200). The resulting packaging material was 150mm long and 90mm wide, with the sealed portion of each side being 5mm wide from the end. Subsequently, a plate-shaped polybutylene terephthalate resin, 70 mm in length and 5 mm in width (area S of the support part), was used as the support part. S 700mm 2A partition member was obtained by attaching a 1.0 mm thick piece of material to two locations at both ends of the outer casing using 0.1 mm thick double-sided adhesive tape, in parallel positions so that a pair of opposite sides are formed 1 mm from the periphery of the short side of the outer casing. When the resulting partition member is used between two different batteries in a battery pack, the thickness of the air layer over the non-contact area is 0.2 mm. Also, the area of ​​the heat insulating part when viewed from above (S I Area of ​​the non-contact region (S) N ) proportion (S N / S I ) becomes 0.92. The fabricated partition members were evaluated using evaluation methods 1 and 2 described above. The results are shown in Table 1 below.

[0055] (Test Example 2) A partition member was obtained in the same manner as in Test Example 1, except that the insulating material was changed to a porous sheet with a different compressive modulus (vermiculite sheet, compressive modulus 7.8 MPa). The results of evaluating the fabricated partition members using evaluation methods 1 and 2 described above are shown in Table 1 below.

[0056] (Test Example 3) As insulation material, porous sheets with different compressive moduli (vermiculite sheets, compressive moduli 5.2 MPa) were used, with a support thickness of 0.92 mm and an air layer thickness (T A The partition members were obtained in the same manner as in Test Example 2, except that the diameter was changed to 0.12 mm. The results of evaluating the fabricated partition members using the evaluation methods 1 and 2 described above are shown in Table 1 below.

[0057] (Test example 4) The thickness of the support section is 2.3 mm, and the thickness of the air layer is (T A The partition members were obtained in the same manner as in Test Example 3, except that the diameter was changed to 1.5 mm. The results of evaluating the fabricated partition members using the evaluation methods 1 and 2 described above are shown in Table 1 below.

[0058] (Test Example 5) The thickness of the support part is 0.85 mm, and the thickness of the air layer (TA The partition members were obtained in the same manner as in Test Example 3, except that the thickness was changed to 0.05 mm. The results of evaluating the fabricated partition members using the evaluation methods 1 and 2 described above are shown in Table 1 below.

[0059] (Test Example 6) The thickness of the support section is 3.3 mm, and the thickness of the air layer is (T A The partition members were obtained in the same manner as in Test Example 3, except that the diameter was changed to 2.5 mm. The results of evaluating the fabricated partition members using the evaluation methods 1 and 2 described above are shown in Table 1 below.

[0060] (Test Example 7) The thickness of the support part is 1.0 mm, and the thickness of the air layer is (T A ) 0.2 mm, area of ​​the insulating part when viewed from above (S I Area of ​​the non-contact region (S) N ) proportion (S N / S I A partition member was obtained in the same manner as in Test Example 3, except that the value of ) was changed to 0.72. The results of evaluating the fabricated partition member using the evaluation methods 1 and 2 described above are shown in Table 1 below.

[0061] (Test Example 8) Area of ​​the insulating part when viewed from above (S I Area of ​​the non-contact region (S) N ) proportion (S N / S I A partition member was obtained in the same manner as in Test Example 7, except that the value of ) was changed to 1.0. The results of evaluating the fabricated partition member using the above evaluation methods 1 and 2 are shown in Table 1 below.

[0062] (Test Example 9) Area of ​​the insulating part when viewed from above (S I Area of ​​the non-contact region (S) N ) proportion (S N / S I A partition member was obtained in the same manner as in Test Example 7, except that the value of ) was changed to 0.39. The results of evaluating the fabricated partition member using the above evaluation methods 1 and 2 are shown in Table 1 below.

[0063] (Test Example 10) Area of ​​the insulating part when viewed from above (S I Area of ​​the non-contact region (S) N ) proportion (S N / S I ) is 0.92, and the area S of the support part S 350mm 2 The partition members were obtained in the same manner as in Test Example 7, except for the change made to [specific part]. The results of evaluating the fabricated partition members using the evaluation methods 1 and 2 described above are shown in Table 1 below.

[0064] (Test Example 11) Area S of the support part S 2340mm 2 The partition members were obtained in the same manner as in Test Example 10, except for the change made to [specific part]. The results of evaluating the fabricated partition members using the evaluation methods 1 and 2 described above are shown in Table 1 below.

[0065] (Test Example 12) Area S of the support part S 250mm 2 The partition members were obtained in the same manner as in Test Example 10, except for the change made to [specific part]. The results of evaluating the fabricated partition members using the evaluation methods 1 and 2 described above are shown in Table 1 below.

[0066] (Test Example 13) Area S of the support part S 3200mm 2 The partition members were obtained in the same manner as in Test Example 10, except for the change made to [specific part]. The results of evaluating the fabricated partition members using the evaluation methods 1 and 2 described above are shown in Table 1 below.

[0067] (Test Example 14) A partition member was obtained in the same manner as in Test Example 3, except that 5 ml of water was added after the insulation material was placed inside the exterior. The results of evaluating the fabricated partition member using the evaluation methods 1 and 2 described above are shown in Table 1 below.

[0068] (Comparative Test Example 1) Except for changing the insulating material to a porous sheet with a different compressive modulus (vermiculite sheet, compressive modulus 0.3 MPa), the partition members were obtained in the same manner as in Test Example 1. The results of evaluating the fabricated partition members using the evaluation methods 1 and 2 described above are shown in Table 1 below.

[0069] (Comparative Test Example 2) Except for changing the insulating material to a porous sheet with a different compressive modulus (vermiculite sheet, compressive modulus 15 MPa), a partition member was obtained in the same manner as in Test Example 1. The results of evaluating the fabricated partition member using the evaluation methods 1 and 2 described above are shown in Table 1 below.

[0070] (Comparative Test Example 3) Thickness of the air layer (T A The partition members were obtained in the same manner as in Test Example 3, except that the value was changed to 0 mm. The results of evaluating the fabricated partition members using the evaluation methods 1 and 2 described above are shown in Table 1 below.

[0071] [Table 1] [Explanation of Symbols]

[0072] 10A, 10B assembled battery 12 single batteries 14, 14A, 14B Partition members 16. Insulation section 18 Support part 20 Non-contact area 22 Exterior 210 terminals 220 terminals

Claims

1. A battery pack comprising multiple single cells stacked together, wherein at least one of the single cells has a partition member, The partition member has a heat insulating portion, and the compressive modulus of the heat insulating portion in the single cell stacking direction is 0.5 to 10 MPa. The partition member is provided with a support portion on the outside of the heat insulating portion in a planar direction perpendicular to the single cell stacking direction, and the support portion is in contact with the single cell. A battery pack in which the partition member has a non-contact area that does not come into contact with the individual cells.

2. The battery pack according to claim 1, wherein the partition member is provided between each individual cell.

3. The battery pack according to claim 1 or 2, wherein the compressive modulus of the support portion in the single-cell stacking direction is 0.5 to 100 MPa.

4. The battery pack according to any one of claims 1 to 3, wherein the distance between the non-contact area and the single cell on the non-contact area is 0.1 to 2.5 mm.

5. Area of ​​the heat insulating part when viewed from above (S Ｉ ) with respect to the area of ​​the non-contact region (S Ｎ The proportion of (S Ｎ / S Ｉ A battery pack according to any one of claims 1 to 4, wherein the ratio is 0.3 to 1.

6. The area of ​​the partition member when viewed from above (S Ｐ The area of ​​the support portion (S) relative to the area of ​​the support portion Ｓ The proportion of (S Ｓ / S Ｐ A battery pack according to any one of claims 1 to 5, wherein the ratio is 0.02 to 0.

2.

7. The battery pack according to any one of claims 1 to 6, wherein the partition member, when viewed from above, is rectangular, and the support portion on the partition member is linear and forms at least one pair of opposite sides.

8. The battery pack according to any one of claims 1 to 7, wherein the heat insulating portion holds a liquid.

9. The battery pack according to claim 8, wherein the heat insulating portion is a porous heat insulating material, and the liquid is held in the porous heat insulating material.

10. The battery pack according to any one of claims 1 to 9, wherein the heat insulating part is housed in the outer casing.

11. The battery pack according to claim 10, wherein the outer casing is a laminate comprising a metal foil and a thermoplastic resin layer.

12. The battery pack according to claim 11, wherein the metal constituting the metal foil is at least one of aluminum, copper, tin, nickel, stainless steel, lead, tin-lead alloy, bronze, silver, iridium, and phosphor bronze.

13. A method for manufacturing a battery pack consisting of multiple single cells stacked together, A partition member is placed between at least one of the aforementioned single cells, The partition member has a heat insulating portion, and the compressive modulus of the heat insulating portion in the single cell stacking direction is 0.5 to 10 MPa. The partition member is provided with a support portion on the outside of the heat insulating portion in a plane direction perpendicular to the single cell stacking direction, the support portion is in contact with the single cell, and the partition member is fixed in a state where pressure is applied in the thickness direction of the heat insulating portion. A method for manufacturing a battery pack, characterized in that the partition member provides a non-contact area in which it does not come into contact with the single cell.

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