Cooling structure between battery cells, battery module, and battery pack

Abstract

A cooling structure between battery cells is provided that can more efficiently suppress the temperature rise of adjacent battery cells even when a battery cell that has overheated is generated. The cooling structure between battery cells is arranged side by side with two sides facing each other, and a plate-shaped metal member having a thermal conductivity of 100 W / m·K or more and a thickness of 0.3 mm or more and contacting each of the opposing sides of the adjacent battery cells, and an insulating layer disposed between the plate-shaped metal members having a thermal conductivity of 1.0 W / m·K or less and a thickness of 0.5 mm or more, thereby forming a multilayer structure of cell / metal member / insulating layer / metal member / cell, and also having a cooling member present in the vicinity of the plurality of battery cells, wherein one end of each of the plate-shaped metal members is in contact with the cooling member.

Description

Technology Field

[0001] The present invention relates to a cooling structure between battery cells, a battery module, and a battery pack. Background Technology

[0002] Electric vehicles utilize multiple battery cells (e.g., lithium-ion secondary batteries) to achieve large storage capacity and high output. While battery cells come in cylindrical, prismatic, and laminated types, prismatic cells are widely adopted for electric vehicles due to their high mechanical strength and good balance of energy density and size. In electric vehicles using prismatic battery cells (hereinafter also simply referred to as "battery cells"), multiple battery modules are used, each consisting of multiple battery cells arranged closely in parallel or series within a limited space. These battery modules are connected to form a battery pack, which is then mounted on the vehicle. Since battery cells generate significant heat during repeated charging and discharging cycles, which accelerates degradation, structures or mechanisms are provided within the battery modules to cool the battery cells using air cooling or water cooling.

[0003] However, even if such cooling structures or cooling mechanisms are provided, there are cases where some battery cells overheat abnormally due to deterioration during repeated charging and discharging, or due to external heat or shock. In this case, a large amount of heat is transferred from the battery cells that overheated abnormally to adjacent battery cells, and as this heat propagates, the entire battery module is damaged. As a countermeasure, for example, Patent Document 1 discloses a technology that suppresses damage to the battery module by providing a battery-to-cell separator between adjacent battery cells. An example of the battery-to-cell separator in the said document describes a stacked structure of an insulating member / a heat-conducting member / an insulating member. By doing so, the transfer of heat between adjacent cells can be suppressed by the insulating member, and furthermore, by bringing the end of the heat-conducting member or the bottom of the battery cell into contact with a cooling plate, the heat generated by the abnormal overheating is transferred and dispersed to other parts, thereby suppressing the propagation of the abnormal overheating. Prior art literature

[0004] International Publication No. 2019 / 167689, International Publication No. 2019 / 167612, Chinese Published Patent Application No. 105489965 The problem to be solved

[0005] However, in recent years, battery cells for electric vehicles have become more energy-dense, and when abnormal heat is generated, the temperature rise of the heat-generating cell becomes higher, making it easier for heat to propagate between adjacent cells. For this reason, heat control technology (cooling technology) to suppress damage to battery modules during abnormal heat generation has been desired more than ever before.

[0006] Meanwhile, in order to reduce the cost of battery modules, there has been a trend in some areas to change the casing material of battery cells from aluminum-based materials, such as aluminum alloys, to iron-based materials, such as steel. Iron-based materials have a thermal conductivity that is about 1 / 5 to 1 / 10 lower than that of aluminum-based materials. Therefore, when iron-based materials are used for the casing, even when using a battery module with increased cooling capacity by contacting the battery case with a cooling mechanism such as a cooling plate, it becomes difficult to transfer and disperse the heat from the battery cells that have generated abnormal heat to other parts through the cooling plate.

[0007] In addition, iron-based materials have a higher melting point than aluminum-based materials. Due to the increased energy in battery cells for electric vehicles in recent years, the maximum temperature during abnormal heat generation can reach 700 to 800°C or higher, exceeding the melting point of aluminum-based materials (approx. 660°C), which creates a very dangerous situation where the casing itself melts and falls off. However, since such melting of the casing does not occur in iron-based materials with a melting point of about 1500°C, iron-based materials can be said to be safer than aluminum-based materials.

[0008] Therefore, the present invention has been made in consideration of the above problem, and the objective of the present invention is to provide a cooling structure between battery cells, a battery module having said cooling structure between battery cells, and a battery pack, which can more efficiently suppress the temperature rise of adjacent battery cells compared to the prior art even when a battery cell that has generated abnormal heat occurs, and even when the casing material of the battery cell at that time is an iron-based material such as steel.

[0009] In addition, the narrower the gap between battery cells, the more compactly the battery pack or battery module can be designed, which is desirable in terms of size reduction. On the other hand, a certain amount of spacing is required when considering factors such as preventing overheating and facilitating the installation of cooling structures. Therefore, the spacing between battery cells needs to be designed with a balance of these factors in mind, and different spacing designs are used for different types of batteries.

[0010] Accordingly, the main objective of the present invention is to provide a cooling structure between battery cells, a battery module having said cooling structure between battery cells, and a battery pack, which, in the above-described problem, particularly under conditions where the spacing between battery cells is the same, is capable of more efficiently suppressing the temperature rise of adjacent battery cells compared to the prior art.

[0011] Furthermore, since it is important to prevent abnormal heat generation in battery cells, it is common practice to use aluminum-based materials with excellent thermal conductivity for the casing, and thus the aforementioned problem could not occur. The aforementioned problem can only arise when an iron-based material is intended to be used for the casing. means of solving the problem

[0012] The inventors, as a result of conducting careful investigations to solve the above problem, devised a multilayer structure (hereinafter referred to as “Structure A”) between adjacent battery cells, comprising “a layer of a metal member with high thermal conductivity that is in thermal contact with the side of one battery cell / an insulating layer disposed between them / a layer of a metal member with high thermal conductivity that is in thermal contact with the side of the other battery cell,” a predetermined thickness for each layer, and a connection of one end of the metal member with high thermal conductivity to a cooling mechanism. By doing so, it was discovered that even when a battery cell with abnormal heat generation occurs, the temperature rise of an adjacent battery cell can be lowered more efficiently than in the prior art.

[0013] In addition, under the above conditions, a case was also examined in which the structure was modified to A and a multilayer structure (hereinafter abbreviated as “Structure B”) was provided between adjacent battery cells, comprising “a layer of insulating material thermally in contact with the side of one battery cell / a layer of a material with high thermal conductivity disposed between them / a layer of insulating material thermally in contact with the side of the other battery cell.” Then, both Structure A and Structure B were compared.

[0014] As a result, it was found that at the beginning of abnormal heat generation, there was almost no difference in cooling capacity between structure A and structure B, but as time passed, a difference occurred, and the case using structure A had a higher cooling capacity than the case using structure B. In addition, it was found that in structure A, the cooling capacity was improved by making the thickness of each component greater than a predetermined value, compared to the case where a single layer of a component with high thermal conductivity was simply provided between battery cells.

[0015] Furthermore, focusing on the thermal resistance at the contact interface between the battery cell and the metal member, it was found that controlling the ratio of the thermal resistance value at the contact interface to the thermal resistance value of the metal member to a value below a predetermined value is desirable because it further improves cooling capacity.

[0016] Furthermore, although the above-mentioned Patent Document 2 discloses a structure similar to the above-mentioned A structure, the invention in this Patent Document 2 is intended for the reflection of electromagnetic waves, and does not disclose the aspect of conducting heat as is the focus of the present invention. In addition, in the above-mentioned Patent Document 2, the thickness of the insulating material is 0.1 to 3 mm, which is thinner than the present invention described in detail below. From this perspective, it can be seen that the focus of the above-mentioned Patent Document 2 is the reflection of electromagnetic waves, and it is not intended for the conduction of heat. Furthermore, the above-mentioned Patent Document 2 does not consider the control of thermal resistance of the contact interface at all.

[0017] In addition, the above-mentioned patent document 3 discloses an invention intended for heat conduction, similar to the present invention. In the above-mentioned patent document 3, sheets or foils such as graphite sheets are used as thermal conductive materials, and their thickness is very thin, at 0.02 mm in the examples, which is different from the present invention. Furthermore, in the above-mentioned patent document 3, the control of thermal resistance of the contact interface is not considered at all.

[0018] The gist of the present invention, completed based on the above findings, is as follows: (1) A cooling structure between adjacent battery cells in a plurality of prismatic battery cells arranged side by side with two sides facing each other, wherein the plate-shaped metal member has a thermal conductivity of 100 W / m·K or more and a thickness of 0.3 mm or more and is in thermal contact with each opposing side of the adjacent battery cells, and an insulating layer having at least one of an insulating member or a gas layer disposed between the plate-shaped metal members that are in thermal contact with each opposing side of the adjacent battery cells, having a thermal conductivity of 1.0 W / m·K or less and a thickness of 0.5 mm or more, thereby forming a multilayer structure of battery cell / plate-shaped metal member / insulating layer / plate-shaped metal member / battery cell between the adjacent battery cells, and further comprising a cooling member that is in thermal contact with each of the plurality of prismatic battery cells or is present in the vicinity of each of the plurality of prismatic battery cells, and the plate-shaped A cooling structure between battery cells, wherein each of the metal members has at least one end thereof in thermal contact with the cooling member, and the two plate-shaped metal members constituting the laminated structure have the same thermal conductivity and thickness, and the ratio of the thickness of the plate-shaped metal member / insulating layer / plate-shaped metal member is 1.0:0.2 to 4.0:1.0. (2) A cooling structure between battery cells described in (1), wherein the side of the battery cell is made of a steel material, and when the thermal resistance at the contact interface between the battery cell and the plate-shaped metal member is Rs and the thermal resistance of the plate-shaped metal member is Rm, Rs / Rm ≤ 3.0.

[0019] (3) The plate-shaped metal member is formed such that the lower portions of the plate-shaped metal member are connected to each other so as to be in thermal contact with each side of the adjacent insulating member, and the plate-shaped metal member with the approximately concave shape is inserted between the adjacent insulating members, and the battery cell is disposed in the approximately concave portion of the insulating member, forming a cooling structure between battery cells as described in (1) or (2).

[0020] delete

[0021] delete

[0022] (4) The above plate-shaped metal member is processed so that its cross-sectional shape is concave and is inserted between adjacent battery cells, forming a cooling structure between battery cells as described in any one of (1) to (3).

[0023] (5) A cooling structure between battery cells described in any one of (1) to (4), wherein the thickness of the plate-shaped metal member is 0.5 mm or more and the thickness of the insulation layer is 1.0 mm or more.

[0024] (6) In each of the plurality of prismatic battery cells, a second plate-shaped metal member having a thermal conductivity of 100 w / m·K or more and a thickness of 0.3 mm or more is present on a side parallel to the direction in which the plurality of prismatic battery cells are arranged side by side, and the second plate-shaped metal member is in thermal contact with the side of the battery cell and at least one end is in thermal contact with the cooling member, a cooling structure between battery cells described in any one of (1) to (5).

[0025] (7) A cooling structure between battery cells described in any one of (1) to (6), wherein the spacing between adjacent battery cells is 1.5 to 5.0 mm.

[0026] (8) A cooling structure between battery cells described in any one of (1) to (7), wherein the plate-shaped metal member and the cooling member are in thermal contact through an adhesive or grease having a thermal conductivity of 1.0 W / m·K or higher.

[0027] (9) The above-mentioned adhesive or grease having a thermal conductivity of 1.0 W / m·K or higher is an adhesive or grease that cures at room temperature, and is a cooling structure between battery cells described in any one of (1) to (8).

[0028] (10) A cooling structure between battery cells described in any one of (1) to (9), wherein the cooling member has a groove and the plate-shaped metal member is fitted into the groove.

[0029] (11) The above-mentioned rectangular battery cell is a cooling structure between battery cells described in any one of (1) to (10), which is formed by stacking laminated battery cells.

[0030] (12) A cooling structure between battery cells described in any one of (1) to (11), wherein the material of the plate-shaped metal member is at least one of aluminum, aluminum alloy, copper, or copper alloy.

[0031] (13) A battery module having a cooling structure between battery cells described in any one of (1) to (12).

[0032] (14) A battery pack having a cooling structure between battery cells described in any one of (1) to (12). Effects of the invention

[0033] As explained above, according to the present invention, even when a battery cell that has undergone abnormal heat generation occurs, and even when the casing material of the battery cell at that time is an iron-based material such as steel, under conditions where the spacing between battery cells is the same, it is possible to suppress the temperature rise of adjacent battery cells more efficiently compared to the prior art. Brief explanation of the drawing

[0034] FIG. 1 is an explanatory diagram schematically illustrating a battery cell cooling structure according to an embodiment of the present invention (cross-sectional view in the longitudinal direction of a battery module). (Example) FIG. 2 is an explanatory diagram schematically illustrating a battery module according to an embodiment of the present invention. FIG. 3a is an explanatory diagram schematically illustrating another example of a battery cell cooling structure according to an embodiment of the present invention (cross-sectional view in the longitudinal direction of a battery module). (Example) FIG. 3b is an explanatory diagram schematically illustrating another example of a battery cell cooling structure according to an embodiment of the present invention (cross-sectional view in the longitudinal direction of a battery module). (Example) FIG. 4 is an explanatory diagram schematically illustrating another example of a battery cell cooling structure according to an embodiment of the present invention (cross-sectional view in the longitudinal direction of a battery module). (Example) FIG. 5 is an explanatory diagram schematically illustrating an example of the thermal tactile sensation of a metal member and a cooling member in a battery cell cooling structure according to an embodiment of the present invention. FIG. 6 is a schematic diagram (cross-sectional view in the long direction of the battery module) for explaining a conventional battery cell cooling structure (comparative example). FIG. 7 is a schematic diagram (cross-sectional view in the longitudinal direction of the battery module) for explaining a battery cell cooling structure (comparative example) in which only a metal member or an insulating member is installed between adjacent battery cells. FIG. 8 is a schematic diagram (cross-sectional view in the longitudinal direction of the battery module) for explaining a battery cell cooling structure (comparative example) in which a gap (air layer) is provided between adjacent battery cells. FIG. 9 is a temperature history diagram comparing the cooling characteristics of each battery cell cooling structure illustrated in FIG. 1, FIG. 6 to FIG. 8, etc. FIG. 10 is an explanatory diagram for explaining a method for measuring the thermal conductivity of a metal member. FIG. 11 is an explanatory diagram for explaining a method for measuring the thermal conductivity of a metal member. FIG. 12 is an explanatory diagram for describing a method for measuring the thermal conductivity of adhesives and grease. FIG. 13 is a diagram showing the results of the cooling characteristics of the example of the present invention and the comparative example in an example (cell spacing 5 mm). FIG. 14 is a diagram showing the results of the cooling characteristics of the present invention example and comparative example in an example (cell spacing 3 mm). FIG. 15 is a diagram showing the results of the cooling characteristics of the present invention example and comparative example in an example (cell spacing 2 mm). FIG. 16 is a diagram showing the results of the cooling characteristics of the example of the present invention and the comparative example in an example (cell spacing 5 mm, metal member U-shaped). FIG. 17 is a diagram showing the results of the cooling characteristics of the present invention example and comparative example in an example (cell spacing 5 mm, metal member on the side of the cell short side as well). FIG. 18 is a diagram showing the results of the cooling characteristics of the present invention example and comparative example in an example (using duralumin or cast iron for the metal member). FIG. 19 is a diagram showing the results of the cooling characteristics of the present invention example and comparative example in an example (using a glass plate in the insulation layer). Specific details for implementing the invention

[0035] Suitable embodiments of the present invention will be described in detail below with reference to the attached drawings. Furthermore, in this specification and drawings, components having substantially the same functional configuration are given the same number to avoid redundant descriptions.

[0036] <Overall structure of the cooling structure between battery cells>

[0037] FIG. 1 is a schematic diagram (cross-sectional view in the longitudinal direction of a battery module) illustrating one embodiment of a cooling structure according to the present invention. With this cooling structure, the temperature rise in a battery cell adjacent to a battery cell that has overheated can be suppressed to a lower level compared to a conventional cooling structure.

[0038] In the structure of FIG. 1, a plurality of prismatic battery cells (hereinafter, the "prismatic battery cells" are simply abbreviated as "battery cells") (10), the casing of which is made of steel or aluminum, are arranged side by side with the two sides (sides with the largest area) of each battery cell (10) facing each other (only some cells are shown in the drawing). The battery cells may be composed of laminated battery cells stacked together.

[0039] On each side of an adjacent battery cell (10), a plate-shaped metal member (20) (hereinafter simply referred to as "metal member (20)") having a thermal conductivity of 100 W / m·K or more (at room temperature 25°C range) and a thickness of 0.3 mm or more is in thermal contact. Therefore, the two plate-shaped metal members (20) are adjacent to each other, just like the adjacent battery cell (10). Between these two adjacent plate-shaped metal members (20), there exists an insulating layer (30) having at least one of an insulating member or a gas layer having a thermal conductivity of 1.0 W / m·K or less (at room temperature 25°C range) and a thickness of 0.5 mm or more.

[0040] Here, in an embodiment of the present invention, "thermally in contact" is not limited to direct contact between two members, but also includes a state in which another member is inserted between two members so that both members are "connected in a manner that allows for heat conduction." Details will be described later.

[0041] The spacing between adjacent battery cells (10) is required to be as small as possible for the compactness or high density of a battery module or battery pack composed of multiple battery cells, and is usually 10 mm or less. In this embodiment, the spacing between adjacent battery cells (10) is 1.5 mm or more, so that the difference in cooling effect compared to the prior art becomes wider.

[0042] Additionally, the lower end of the plate-shaped metal member (20) is in thermal contact with the upper surface of the cooling member (40) located below the battery cell (10). In this embodiment, the cooling member (40) is composed of a cooling plate (41) that is water-cooled and a thin thermal sheet (42) that is bonded thereto for electrical insulation. The cooling member (40) that is in thermal contact with the plate-shaped metal member (20) may be located near the battery cell (10), and may be located above or to the side in addition to below. That is, the cooling member (40) may be located in a position where the end of the metal member (20) and the cooling member (40) can easily come into contact by being located near the battery cell (10). Furthermore, the cooling member (40) may be in thermal contact with the battery cell (10) to directly cool the battery cell (10). For improved cooling performance, it is preferable that the cooling member (40) be present in multiple positions among the lower, upper, and side. For example, in the example illustrated in FIG. 2, in addition to the plate-shaped metal member (20), a second plate-shaped metal member (60) located above the battery cell (10) and a third plate-shaped metal member (70) located to the side of the battery cell (10) are provided. Furthermore, to simplify the structure, it is preferable that the plate-shaped metal member (20) be present only below the battery cell (10).

[0043] Additionally, preferably as shown in FIG. 1, the battery cell (10) is loaded onto a cooling member (40) located below it, and the lower surface of the battery cell (10) and the upper surface of the cooling member (40) are in thermal contact.

[0044] In addition, for each battery cell (10), in addition to the two sides with the largest area (two sides on the long side), the remaining two sides (two sides on the short side) that are parallel to the direction in which a plurality of rectangular battery cells (10) are arranged side by side (sides extending in the same direction) are thermally contacted by a plate-shaped metal member (20) having a thermal conductivity of 100 w / m·K or more and a thickness of 0.3 mm or more, and also thermally contact the upper surface of a cooling member (40) located below it (not shown).

[0045] In addition, the metal member (20) may also be provided with an insulating member having a thermal conductivity of 1.0 W / m·K or less and a thickness of 1.0 mm or more (not shown). In this case, a plate-shaped metal member (20) may be installed on each of the two short-side surfaces of each battery cell (10), but as shown in FIG. 2, a plate-shaped metal member (20) may be installed on each of the two short-side surfaces of the battery cell (10) across all the battery cells (10) constituting the battery module.

[0046] By having such a structure, when some of the multiple battery cells (10) begin to generate excessive heat, the heat can be transferred through the metal member (20) to a nearby cooling member (40). Additionally, the thermal insulation member can suppress the transfer of heat to neighboring battery cells (10) and efficiently suppress the temperature rise of neighboring battery cells (10).

[0047] In particular, the present cooling structure can efficiently suppress the temperature rise of adjacent battery cells (10) even when steel is used in the casing of the battery cell (10) for cost reduction, and each side of the adjacent battery cell (10) is composed of steel material with a thermal conductivity one order of magnitude lower than that of aluminum material. Therefore, when the present cooling structure is applied to a battery cell in which steel is used on the side of the cell, the difference in effect from the conventional technology becomes more pronounced, which is desirable.

[0048] <Regarding plate-shaped metal members>

[0049] Since the plate-shaped metal member (20) efficiently transfers the heat from the battery cell (10) that has started to generate heat to the cooling member (40) located nearby, it is necessary for the plate-shaped metal member (20) to have a thermal conductivity of 100 W / m·K or higher and a thickness of 0.3 mm or higher. In addition to the relative superiority of cooling capacity compared to conventional technology, the thickness of the plate-shaped metal member (20) is preferably 0.5 mm or higher, and more preferably 1.0 mm or higher, in terms of lowering the value of the reached temperature itself. Meanwhile, the thickness of the plate-shaped metal member (20) is determined by considering the spacing between adjacent battery cells (10) and the thickness of the insulation layer (30), but practically, the upper limit is about 5.0 mm. The thickness of the plate-shaped metal member (20) is preferably 5.0 mm or less, and more preferably 2.0 mm or less. In addition, the thermal conductivity is preferably 150 W / m·K or higher. Meanwhile, the thermal conductivity of the plate-shaped metal member (20) is substantially limited to about 420 W / m·K. More preferably, the plate-shaped metal member (20) has a thickness of 1.0 mm or more and a thermal conductivity of 150 W / m·K or more.

[0050] The thickness of the plate-shaped metal member (20) does not necessarily have to be a constant thickness, and the shape of the metal member may be tapered, have steps, or have irregularities. In the case of these shapes, an average value can be used as the value of the plate thickness described above. This average value of the plate thickness can be calculated as (volume of the plate-shaped metal member (20)) ÷ (projected area of ​​the plate-shaped metal member (20) from the plate thickness direction).

[0051] There are no particular restrictions on the material of the metal member. However, aluminum, aluminum alloys, copper, and copper alloys (including brass) are preferred as the material of the metal member due to the balance of high thermal conductivity and low cost.

[0052] The range of the metal member (20) that is in thermal contact with the side (the side with the largest area) of the battery cell (10) may be partial, but it is preferable to make it at least 70% of the area of ​​the side of the battery cell (10), and more preferable to make it at least 90%. In addition, since the temperature rise of the battery cell (10) during abnormal heat generation is generally considered to be higher the further it is from the cooling member (40), it is preferable that the metal member (20) be in thermal contact with the part far from the cooling member (40). In the cooling structure of FIG. 1, since the cooling member (40) is installed downward, it is preferable that the metal member (20) be installed to make thermal contact from the upper side of the battery cell (10) as in FIG. 1. More specifically, it is more preferable that the metal member (20) be installed to make thermal contact with the side of the battery cell (10) for at least 90% of the vertical length of the side of the battery cell (10).

[0053] Additionally, as shown in FIG. 3a, the lower portions of plate-shaped metal members (20) that are in thermal contact with each side of adjacent insulating members (30) are connected to form a concave shape (in other words, after the cross-sectional shape of the plate-shaped metal members (20) is made to form a concave shape), and then such metal members (20) are inserted between adjacent insulating members (30), and a battery cell (10) may be installed in the concave portion of the plate-shaped metal members (20). By doing so, the desired insulating state can be achieved simply by inserting the metal member (20) with the battery cell (10) installed between adjacent insulating members (30), and thus productivity is further improved.

[0054] At this time, the corner portion of the concave metal member (20) may be at a right angle as shown in FIG. 3a, or may be in a curved state as shown in FIG. 3b.

[0055] <About the insulation layer>

[0056] In order to suppress the transfer of heat to neighboring battery cells (10) when some battery cells (10) overheat, the insulation layer (30) needs to have a thermal conductivity of 1.0 W / m·K or less and a thickness of 0.5 mm or more. As the insulation capacity of the insulation layer (30) increases, the initial temperature rise in battery cells adjacent to the overheated battery cells can be suppressed. Therefore, from the perspective of suppressing the initial temperature rise, the thermal conductivity of the insulation layer (30) is preferably 0.1 W / m·K or less, and more preferably 0.06 W / m·K or less. Additionally, the lower limit of the thermal conductivity of the insulation layer (30) is substantially about 0.02 W / m·K. Likewise, from the perspective of suppressing the initial temperature rise, the thickness of the insulation layer (30) is preferably 1.0 mm or more, and more preferably 1.5 mm or more. Meanwhile, the thickness of the insulation layer (30) is determined by taking into account the spacing between adjacent battery cells (10) and the thickness of the plate-shaped metal member (20), but practically, the upper limit is about 10.0 mm. The thickness of the insulation layer (30) is preferably 5.0 mm or less, and more preferably 2.0 mm or less.

[0057] The material of the insulation layer (30) is not particularly limited, but may use an insulating material such as glass wool, rock wool, urethane foam, foamed rubber, nonwoven fabric, polystyrene, polypropylene, or resin such as polybutylene terephthalate. Additionally, the insulation layer (30) may be a gas layer in which a gas such as air exists in the space. Furthermore, the insulation layer (30) may be formed by using a member capable of holding and supporting a gas layer, such as a porous member, between adjacent metal members (20), so that a gas such as air exists inside the hole.

[0058] The insulating layer (30) may exist between two adjacent plate-shaped metal members (20).

[0059] When an insulating member is used as the insulating layer (30), the insulating layer (insulating member) (30) may be in contact with the metal member (20) or may be spaced apart with a gap. Additionally, one side of the insulating layer (insulating member) (30) may be in contact with the metal member (20), and the other side may be spaced apart with a gap from the metal member (20). When the insulating member (30) and the metal member (20) are in contact, both can be fixed using an adhesive.

[0060] Additionally, it is sufficient to simply insert an insulating layer (insulating member) (30) between two adjacent plate-shaped metal members (20). In this case, it is preferable to insert an insulating layer (insulating member) (30) with relatively high rebound elasticity between two adjacent plate-shaped metal members (20) and use it to press the metal members (20). As a result, the metal members (20) are pressed against the side of the battery cell (10), thereby reducing the contact resistance (thermal resistance) and further improving the cooling effect.

[0061] In addition, even if the insulation layer (30) consists only of a gas layer (air gap) such as air, if the gas layer is not actively convected, the influence of radiant heat in the temperature range of about 100°C is extremely minimal, so the gas layer is insulated between the plate-shaped metal members (20) with a low thermal conductivity. For example, if the insulation layer (30) is an air layer, there is no significant difference in insulation effect compared to the case of glass wool. However, if the insulation layer (30) consists only of a gas layer, natural convection of gas occurs because a temperature gradient occurs around the battery cell (10), and depending on the surrounding structure, an increase in the heat transfer rate between the plate-shaped metal members (20) due to convective heat conduction may also occur. Therefore, it is more preferable to use an insulating material for the insulation layer (30).

[0062] In the case where there is a gap between the insulation layer (insulation member) (30) and the metal member (20), the air layer present in this gap serves to provide an insulation effect between two adjacent plate-shaped metal members (20) together with the insulation member (30). In this case, the insulation layer (insulation member) (30) can be fixed to the lower cooling structure (40) with an adhesive or the like. Additionally, it is sufficient to simply stack the insulation member (30) between two adjacent plate-shaped metal members (20).

[0063] It is preferable that the installation location and area of ​​the insulation layer (insulating member) (30) be such that it covers at least the entire surface of the metal member (20). This is because, in the event of abnormal heat generation of the battery cell (10), heat dissipation from the side of the metal member (20) can be suppressed, thereby allowing the heat of the battery cell (10) to be efficiently transferred from the metal member (20) to the cooling member (40). Furthermore, it is more preferable to position it so as to face the entire side of the battery cell (10), in that this suppresses the transfer of heat to neighboring battery cells (10).

[0064] In addition, as shown in FIG. 4, the lower portions of plate-shaped metal members (20) that are in thermal contact with each side of adjacent battery cells (10) may be connected to form a concave shape (in other words, the cross-sectional shape of the plate-shaped metal members (20) may be made concave), and such metal members (20) may be inserted between the battery cells (10). Furthermore, an insulating layer (insulating member) (30) may be installed in the concave portion of the plate-shaped metal members (20). By doing so, the desired insulating state can be achieved simply by inserting the metal members (20) between adjacent battery cells (10), thereby further improving productivity. In addition, the insulating layer (insulating member) (30) can be installed stably. It is preferable that the height of the connection portion of the lower portion of the metal member (20) be 1 / 4 or less of the total height of the metal member (20) to sufficiently maintain the insulating effect of the insulating member (30).

[0065] <About the duplex structure>

[0066] In this embodiment, as illustrated in FIG. 2, a multilayer structure of battery cell (10) / plate-shaped metal member (20) / insulating layer (30) / plate-shaped metal member (20) / battery cell (10) is formed between adjacent battery cells. In this multilayer structure, the characteristics of each of the plate-shaped metal member (20), insulating layer (30), and plate-shaped metal member (20) are as described above. There is no limitation on the entire multilayer structure as long as it is within the range described above. For example, the two plate-shaped metal members (20) existing between adjacent cells may have different thermal conductivity and thickness. However, if the characteristics of both are identical, the balance of the cooling structure as a whole is excellent, and it is also desirable in terms of suppressing temperature non-uniformity and ease of manufacturing.

[0067] When the thermal conductivity and thickness of two adjacent plate-shaped metal members (20) are the same, regarding the ratio of the thickness of the plate-shaped metal member (20) / insulating layer (30) / plate-shaped metal member (20), when the thickness of the plate-shaped metal member (20) is 1.0, it is preferable that the thickness of the insulating layer (30) be 0.2 to 4.0, and more preferable that it be 0.5 to 3.0. That is, the ratio of the thickness of the plate-shaped metal member (20) / insulating layer (30) / plate-shaped metal member (20) is preferably 1.0:0.2 to 4.0:1.0, and more preferable that it be 1.0:0.5 to 3.0:1.0.

[0068] Regarding thermal contact

[0069] (Thermal contact between the side of the battery cell and the plate-shaped metal member)

[0070] In the present embodiment, the situation in which the side of the battery cell (10) and the plate-shaped metal member (20) are in thermal contact includes, in addition to the case where the two are in direct contact, a case in which the two are connected (in contact) in a manner that allows for heat conduction through a contact member such as an adhesive, grease, or a thin sheet (not shown).

[0071] Even when the two are in direct contact, there is contact resistance at the contact interface caused by slight differences in surface roughness or curvature between the two. Therefore, the thermal resistance from the surface of the battery cell (10) to the surface of the insulating material side of the plate-shaped metal member (20) is greater than the thermal resistance of the plate-shaped metal member (20) alone. The thermal resistance Rs at the contact interface is preferably Rs / Rm ≤ 3.0 compared to the thermal resistance Rm of the plate-shaped metal member (20) alone, more preferably Rs / Rm ≤ 1.5, and even more preferably Rs / Rm ≤ 1.0. Additionally, the thermal resistance Rs at the contact interface is expressed as L / λ or 1 / h [m²·K / W]. Here, in the case where a contact member is used, L represents the thickness of the contact member present at the contact interface, λ represents the thermal conductivity of the contact member, and h represents the heat transfer rate at the contact interface.

[0072] In order to reduce the thermal resistance Rs at the contact interface, in the case of direct contact, the surface roughness (irregularity) of the side of the battery cell (10) and the plate-shaped metal member (20) can be reduced by polishing, etc., or the pressure of the plate-shaped metal member (20) on the side of the battery cell (10) can be increased.

[0073] Additionally, the side of the battery cell (10) and the plate-shaped metal member (20) may be thermally brought into contact through an adhesive or grease. This is desirable because using an adhesive or grease allows the surface irregularities of both to be filled, thereby easily increasing the actual contact area. When using an adhesive or grease, it is preferable to use one with high thermal conductivity having a thermal conductivity of 1.0 W / m·K or higher. The thermal conductivity of the adhesive or grease is more preferably 2.0 W / m·K or higher, and even more preferably 4.0 W / m·K or higher. Meanwhile, the thermal conductivity of the adhesive or grease is substantially capped at approximately 10.0 W / m·K. It is preferable to apply the adhesive or grease thinly enough to fill the irregularities of both, as this reduces thermal resistance. Depending on the degree of irregularity, it is preferable to apply the adhesive or grease with a thickness of, for example, about 0.01 to 0.2 mm.

[0074] Additionally, the side of the battery cell (10) and the plate-shaped metal member (20) may be thermally contacted through a thin sheet such as a heating sheet. A heating sheet made of a flexible material such as silicone rubber is preferred because, just like adhesives or grease, it can easily increase the actual contact area by embedding the surface irregularities of both. Furthermore, if a heating sheet having electrical insulation properties is used, electrical insulation between cells can also be secured. Since heating sheets often have a thicker thickness than adhesives or grease, a higher thermal conductivity is preferable. For example, a thermal conductivity of 2 W / m·K or higher is preferable, and 10 W / m·K or higher is more preferable. Meanwhile, the thermal conductivity of the heating sheet is practically limited to about 50 W / m·K.

[0075] In addition, ceramic fillers, etc., may be mixed into adhesives, greases, or heating sheets to improve thermal properties or provide electrical insulation properties before use.

[0076] It is known that lithium-ion secondary batteries, which are one of the representative battery cells, undergo expansion and contraction due to charging and discharging. At this time, grease, which behaves similarly to a liquid, may be extruded from the gap due to repeated expansion and contraction, potentially causing a "pump-out phenomenon." To prevent this pump-out phenomenon, it is more desirable to use an adhesive that becomes solid after curing (more specifically, an adhesive that solidifies at room temperature) or a solid thermal sheet. In particular, since the adhesive cures to conform to the shape and gap, it is possible to conduct heat from the battery cell (10) without being affected by thickness, shape, deformation, or surface irregularities. Among these, a flexible and elastic adhesive is particularly desirable because it easily deforms to conform to the expansion and contraction, and does not crack or break even with repeated expansion and contraction.

[0077] Regarding the thickness of such adhesives, grease, and heating sheets, a thinner thickness is preferable from the perspective of thermal conductivity, while a thicker thickness is preferable from the perspective of accommodating expansion and contraction. Considering this trade-off relationship, the thickness of the adhesives, grease, and heating sheets is preferably 1 μm or more, and more preferably 5 μm or more. Additionally, the thickness of the adhesives, grease, and heating sheets is preferably 2 mm or less, and more preferably 500 μm or less.

[0078] In the case where the side of the battery cell (10) and the plate-shaped metal member (20) are thermally contacted through a contact member such as an adhesive, grease, or a heating sheet, just as in the case of direct contact, the thermal resistance Rs of the adhesive, grease, or heating sheet is preferably Rs / Rm ≤ 1.5 when compared to the thermal resistance Rm of the plate-shaped metal member (20) alone, more preferably Rs / Rm ≤ 0.8, and even more preferably Rs / Rm ≤ 0.5. In this case, the adjustment of Rs / Rm can be achieved by selecting a material (thermal conductivity) and setting the thickness.

[0079] (Thermal contact between the end of a plate-shaped metal member and a cooling member)

[0080] In the present embodiment, the situation in which one end of a plate-shaped metal member (20) (in FIG. 1, the end located on the cooling member side among the four ends due to the rectangular plate shape) and the cooling member (40) are in thermal contact includes, in addition to the case where the two are in direct contact, similar to the thermal contact between the side of the battery cell and the plate-shaped metal member, the case where the two are connected (in contact) in a way that allows for heat conduction through an adhesive, grease, or a thin-thickness heating sheet. FIG. 1 illustrates an example using a thin-thickness sheet (heating sheet (41)).

[0081] In FIG. 1, one end of a plate-shaped metal member (20) is loaded directly onto a heat transfer sheet (41) constituting the upper surface of a cooling member (40) and is in thermal contact. Here, as shown in FIG. 5, the plate-shaped metal member (20) may be placed inside the cooling member (40). A structure as shown in FIG. 5 can be realized, for example, by providing a groove in the cooling member (40) and inserting the end of the plate-shaped metal member (20) into the groove to make thermal contact. By making such a structure, it becomes possible to increase the contact area between the plate-shaped metal member (20) and the cooling member (40), or to reduce the actual thermal resistance between the plate-shaped metal member (20) and the cooling member (40), and it becomes possible to cool the battery cell (10) that has overheated more effectively. In FIG. 5, a heat transfer sheet (50) installed between the plate-shaped metal member (20) and the side of the battery cell (10) is extended together with the plate-shaped metal member (20) and embedded in the groove of the cooling member (40) together with the plate-shaped metal member (20), thereby securing thermal contact between the cooling member (40) and the plate-shaped metal member (20).

[0082] <Regarding Cooling Characteristics>

[0083] By adopting the structure of the present embodiment, the cooling capacity can be improved compared to the prior art. Here, the cooling characteristics of the structure of the present embodiment shown in FIG. 1 are specified by comparing them with the prior art shown in FIG. 6 to 8.

[0084] The cooling structure illustrated in FIG. 6 is the cooling structure of FIG. 1 in which the positions of the metal and the insulating material are swapped (the thickness of the metal member is the same as the total thickness of the two metal members in FIG. 1, and the total thickness of the two insulating members is the same as the thickness of the insulating layer in FIG. 1). The rest of the structure is the same as FIG. 1. That is, it has a multilayer structure of “cell / insulating member / metal member / insulating member / cell” and has a cooling structure in which one end of the metal member is in thermal contact with the cooling member below. The cooling structures illustrated in FIG. 7 and FIG. 8 respectively illustrate a cooling structure in which only a metal member (20) is installed between the battery cells and a cooling structure in which only an insulating member (30) is installed (the thickness of the metal member and the insulating member is the same as the thickness of the multilayer structure in FIG. 1). The rest of the structure is the same as FIG. 1 (in FIG. 7, the metal member is in thermal contact with the cooling member below).

[0085] FIG. 9 is a temperature history diagram schematically illustrating the difference in cooling characteristics when using the cooling structures of FIG. 1 and FIG. 6 to FIG. 8, and shows the change over time in the temperature of a battery cell adjacent to a battery cell where abnormal heat generation occurred (at the part thought to be the hottest).

[0086] It can be seen that the cooling structure of the present embodiment of Fig. 1 ultimately has the lowest temperature and the best cooling capacity. The cooling structure of Fig. 5 exhibits a temperature change similar to that of the cooling structure of Fig. 1 up to a certain point, but around 1000 seconds, it begins to diverge in the direction of higher temperature, and the temperature ends up being higher than that of the cooling structure of Fig. 1. In the cooling structure of Fig. 7, which is equipped with only a metal member, the temperature rises the fastest initially, but the temperature rise is mitigated midway, resulting in the next lowest temperature after Figs. 1 and 6. In the cooling structure of Fig. 8, which is equipped with only an insulating member, the temperature rise is slower than that of the cooling structure of Fig. 7 equipped with only a metal member initially, but this reverses around 1000 seconds, resulting in the highest temperature at the end. Furthermore, it was found that in the cooling structure of Fig. 8, when the insulating member is made of only an air layer, the result of the temperature trend is approximately the same as in the case where only an insulating member is used.

[0087] As described above, it was found that the cooling capacity of the cooling structure of FIG. 1 is a result that cannot be easily predicted from the cooling capacity of the cooling structures of FIG. 6 to FIG. 8.

[0088] The superior cooling capacity of the cooling structure according to the present invention is achieved when a plate-shaped metal member with a thermal conductivity of 100 W / m·K or higher and a thickness of 0.3 mm or higher is used, and an insulating layer with a thermal conductivity of 1.0 W / m·K or lower and a thickness of 0.5 mm or higher is used. Outside of this range, no superiority occurs, and in some cases, it was observed that a phenomenon such as the structure of FIG. 7, in which only a metal member exists, results in a lower maximum temperature.

[0089] Regarding the manufacturing method of the cooling structure

[0090] The manufacturing method of the present embodiment is not particularly limited. Thermal contact of the plate-shaped metal member (20) with the side of an adjacent battery cell (10), thermal contact of at least one end of the plate-shaped metal member (20) with a cooling member (40), and installation of an insulating layer (30) between adjacent plate-shaped metal members (20) may be appropriately performed.

[0091] Regarding the evaluation method of thermal conductivity

[0092] (Method for evaluating the thermal conductivity of plate-shaped metal members)

[0093] The thermal conductivity of the plate-shaped metal member (20) can be determined as a physical property value inherent to the material if the material of the plate-shaped metal member (20) is known.

[0094] If the material of the plate-shaped metal member (20) is unknown, or if the material is known but the physical property value of the thermal conductivity is not known, it is measured by the Straight Fin Temperature Fitting (SFTF) method. With reference to FIGS. 10 and 11, the method for measuring the thermal conductivity of the plate-shaped metal member (20) will be briefly explained.

[0095] Here, if the plate-shaped metal member (20) is already placed on the surface of the battery cell (10), the thermal conductivity is measured after removing the plate-shaped metal member (20) from the surface of the battery cell (10). Additionally, if the plate-shaped metal member (20) is placed on the surface of the battery cell (10) through a heating sheet, the thermal conductivity is measured after separating the plate-shaped metal member (20) from the heating sheet.

[0096] Specifically, if the plate-shaped metal member (20) is in contact with the battery cell (10) via grease, the plate-shaped metal member (20) can be detached in the vertical direction of the battery cell (10) and the grease can be wiped off to provide for measurement. Additionally, if the plate-shaped metal member (20) is bonded to the battery cell (10) by an adhesive, the plate-shaped metal member (20) is detached from the battery cell (10) using a tool such as a scraper, and the surface of the plate-shaped metal member (20) is polished to expose the surface of the plate-shaped metal member (20) and smooth the surface. If the plate-shaped metal member (20) is in contact with the electric heating sheet, the plate-shaped metal member (20) is similarly peeled off to provide for measurement.

[0097] After that, the surface closest to the surface of the battery cell (10) in the plate-shaped metal member (20) is set as the measurement surface, and all parts except this measurement surface and the part where heat flow is input are covered with an insulating material. By doing so, a test specimen of the plate-shaped metal member (20) provided for the SFTF method can be obtained.

[0098] FIG. 10 is an explanatory diagram for explaining the principle of the SFTF method. For a flat plate test specimen with length Lt [m], cross-sectional area A [m²] = H × t, and perimeter length P [m] = 2 × (Lt + H + t), as shown at the top of FIG. 10, when one end is heated and the other end is cooled, the boundary temperature T0 = T at the heat flow input site is x0 and, temperature rise distribution T from the surrounding air of the test specimen i Measure (i=1 to n: temperature measurement points).

[0099] Meanwhile, the analytical solution T regarding the temperature distribution of the straight pin xiThe temperature distribution analysis equation for a straight pin that is given is given in the following equation (101) by using the boundary conditions of the test specimen's single-stage temperature fixation and single-section insulation. Thus, the obtained measured value Txi is compared with the temperature rise analysis solution Tx of the straight pin given in equation (101) to calculate the standard deviation σ specified in the following equation (103), and the parameter m in the analysis equation is determined so that this standard deviation is minimized.

[0100] In addition, the in-plane thermal conductivity of the sample of interest (thermal conductivity in the length Lt direction in FIG. 10) is k p If expressed as such, the parameter m in the analytical equation represented by Equation (101) is the average heat transfer rate h from the surface of the test specimen to the surrounding air. m Using this, it is expressed as in the following equation (105).

[0101] In addition, the average heat transfer rate h m It is expressed as the following equations (107) to (111) using the theoretical formulas for the natural convection heat transfer rate and the radiative heat transfer rate of a vertical plate. Here, in the following equations (107) to (111), h nm ε is the natural convection heat transfer rate for a vertical plate of height H, and h rm ε is the radiative heat transfer rate from a surface with emissivity ε. Also, k a , v a , β, and Pr are the thermal conductivity, kinematic viscosity, expansion rate, and Plantl number of air, respectively. Also, g is the acceleration due to gravity, and σ' is the Stefan-Boltzmann constant (= 5.67 × 10⁻⁶). -8 W / ㎡·K 4 ) is. T m , T a ε₀ and ε₀ are the average temperature of the test specimen and the ambient temperature, respectively, expressed in absolute temperature. ΔTm is the average temperature rise of the test specimen and can be calculated by ΔT0·φ using the fin efficiency φ (0.8) and the temperature rise ΔT0 at x=0.

[0102]

[0103] When measuring the thermal conductivity of an actual metal member, the metal member to be measured is cut to a size of 20 mm in width × 200 mm in length, and a laminated structure as shown in FIG. 11 is formed, a heater is installed on one end, and the heater output is set to 1.6 W at 10 V. Then, the temperature distribution within the surface of the metal member is captured with a thermocamera, and the obtained thermal image is converted into a temperature distribution to verify the relationship between the test length and the surface temperature. By analyzing the obtained relationship between the test length and the surface temperature using the straight pin temperature distribution fitting method described above, the thermal conductivity of the metal member of interest can be obtained. In addition, if the size of the metal member is small and it cannot be cut to a size of 20 mm in width × 200 mm in length, the test specimen can be made smaller, such as 20 mm in width × 100 mm in length, and the measurement can be performed.

[0104] In addition, in a structure in which a heat transfer sheet exists between a battery cell and a plate-shaped metal member, the method for measuring the thermal conductivity of the heat transfer sheet can be performed in the same way as the method for measuring the thermal conductivity of the plate-shaped metal member described above.

[0105] (Method for evaluating the thermal conductivity of adhesives and grease)

[0106] The thermal conductivity of adhesives and grease can be measured by the thermal resistance measurement method in accordance with ASTM 5470 as follows.

[0107] As illustrated in the left side of FIG. 12, a sample of interest is placed between the upper meter bar and the lower meter bar, and power is applied to the heater on the upper meter bar side. Meanwhile, the test head on the lower meter bar side is maintained at a constant temperature by means such as water cooling. Then, the thermal resistance of the sample is calculated from the relationship between the position and temperature of the upper meter bar and the lower meter bar. Specifically, thermocouples are mounted at the positions indicated by T1 to T4 in the drawing, and the surface temperature on the upper meter bar side of the sample is calculated based on the temperature gradient calculated from the temperatures obtained at T1 to T2, and the surface temperature on the lower meter bar side of the sample is calculated based on the temperature gradient calculated from the temperatures obtained at T3 to T4. By doing so, the temperature difference ΔT inside the sample is calculated. Additionally, the thermal resistance of the sample can be calculated by using the amount of heat Q[W] from the heater.

[0108] While varying the thickness of the sample, the thermal resistance of the sample is calculated as described above, and the obtained results are plotted on a coordinate plane defined by the sample thickness and thermal resistance as shown at the bottom of Fig. 12. Then, the distribution of the obtained plot is approximated as a straight line by the least squares method, and the slope of the straight line is calculated. The reciprocal of the obtained slope becomes the thermal conductivity of the sample of interest.

[0109] Unlike the transistor method or the model heater method, the above method for measuring thermal conductivity allows for changing the applied pressure on the upper meter bar side, making it possible to evaluate the thermal resistance with respect to the applied pressure with good reproducibility. In actual measurements, thin films with thicknesses of 0.5 mm, 1.0 mm, and 1.5 mm are fabricated and cut into squares with sides of 20 mm. Then, the cut samples are inserted into the meter bar for measurement. At this time, the material of the meter bar is set to SUS304 (square with sides of 20 mm), and the load during measurement is set to 3 kg / ㎠. Then, the slope is calculated from the relationship between thermal resistance and thickness, and the thermal conductivity is calculated from the reciprocal of the slope.

[0110] In addition, if only a small amount of the adhesive or grease of interest is obtained, the adhesive or grease of interest is dissolved in a suitable organic solvent, and the undissolved filler particles are extracted. The type of filler particles is identified by subjecting the extracted filler particles to component analysis by fluorescent X-rays and crystal structure analysis by X-ray diffraction. In addition, regarding the composition of the matrix resin, the type of matrix resin is identified by observing the obtained resin solution by infrared spectroscopy. Furthermore, the thermal conductivity can be calculated from the amount of extracted filler and the amount of matrix using the following equation (121).

[0111] Here, in the following equation (121), λ matrix is the thermal conductivity of the matrix resin, and λ filler is the thermal conductivity of the filler particles, and λ composite is the thermal conductivity of the composite. Also, φ is the filler content (volume fraction), and x is the shape factor of the filler (when it is spherical, it becomes minimum at x=2).

[0112]

[0113] Regarding the evaluation method of thermal resistance

[0114] The thermal resistance (Rm) of a plate-shaped metal member can be calculated from the thermal conductivity (λm) of the plate-shaped metal member obtained by the evaluation method described above and the thickness (Lm) of the plate-shaped metal member using the formula Rm = Lm / λm.

[0115] In addition, the thermal resistance (Rs) of the adhesive, grease, and heating sheet can be calculated from the thermal conductivity (λs) of the adhesive, grease, and heating sheet obtained by the evaluation method described above and the thickness (Ls) of the adhesive, grease, and heating sheet, using the formula Rs = Ls / λs.

[0116] By using this evaluation method to determine Rm and Rs, the above-described Rs / Rm can be calculated.

[0117] <About Battery Modules and Battery Packs>

[0118] Any battery module and battery pack having a cooling structure between battery cells in the embodiments of the present invention described above may be used. The battery pack may be configured such that a plurality of battery packs are arranged in parallel in a horizontal or vertical direction, or it may be a single battery module.

[0119] Examples

[0120] Hereinafter, while presenting examples and comparative examples, the cooling structure between battery cells according to the present invention, and the battery cell module and battery pack having said cooling structure, will be described with specific examples. Furthermore, the examples presented below are merely examples of the present invention, and the present invention is not limited to the following examples.

[0121] [Battery Cells and Battery Modules]

[0122] For the battery cells, prismatic cells (length 27 mm × width 170 mm × height 115 mm) with a steel casing were used, and eight of these cells were arranged in a straight line facing each other to manufacture a battery module. Four types of battery modules were prepared with cell gaps of 0.5 mm, 2 mm, 3 mm, and 5 mm.

[0123] [Charge / Discharge Test Device]

[0124] For the charge and discharge test of the fabricated module, an EVT60V120A manufactured by Nittetsu Tex Engine Co., Ltd. was used.

[0125] [Cooling device]

[0126] For the cooling device functioning as a heat cooling mechanism, a custom-made water cooling device (length 190 mm × width 400 mm × height 40 mm) was used, a battery module was placed on top of it, and the battery was charged and discharged. The battery cell cooling mechanism realized in this way has a structure roughly as illustrated in the cross-sectional view of FIG. 1 (longitudinal cross-section of the battery module).

[0127] [Metal component and insulation layer]

[0128] As a plate-shaped metal member, an aluminum plate with a thermal conductivity of 235 W / m·K at room temperature was used. In the present invention example, silicone grease manufactured by Shin-Etsu Chemical Co., Ltd. (G-777, thermal conductivity at room temperature 3.3 W / (m·K)), adhesive manufactured by Semedine Co., Ltd. (SX1008, thermal conductivity at room temperature 1.7 W / (m·K), abbreviated as "Adhesive 1" in Table 1 below), or adhesive manufactured by Semedine Co., Ltd. (RH96L, thermal conductivity at room temperature 2.1 W / (m·K), abbreviated as "Adhesive 2" in Table 1 below) was applied thinly (about 0.02 mm thick) to the aluminum plate and attached to the cell. At this time, for a rectangular cell, an aluminum plate was attached to approximately the entire surface of the cell side of the attached surface (excluding a few mm at the top and a few mm at the left and right ends; area ratio of 95% or more). In addition, the attached aluminum plate was connected to a water cooling device installed under the battery module using silicone grease manufactured by Shin-Etsu Chemical Co., Ltd. (G-777, thermal conductivity at room temperature 3.3 W / (m·K)) (applied at approximately 0.1 mm). The ratio of the thermal resistance of the metal member to the thermal resistance Rs of the grease or adhesive (Rs / Rm) is shown in Table 1 below.

[0129] As an insulating material in the insulating layer, glass wool with a thermal conductivity of 0.05 W / m·K at room temperature, or Nichias refractory cloth (TOMBO No. 8300, thermal conductivity of 0.10 W / m·K at room temperature) adjusted to the desired thickness was used.

[0130] [About duplex structures]

[0131] As for the structure between adjacent cells, in the example of the present invention, a multilayer structure of cell / aluminum plate / glass wool / aluminum plate / cell was used. In the comparative example (prior art), a multilayer structure of cell / glass wool / aluminum plate / glass wool / cell, a structure with only an aluminum plate, and a structure with only glass wool were used. The thickness of each member in each structure is shown in Table 1 below.

[0132] In addition, cooling capacity was measured for a cooling structure roughly exemplified in the cross-sectional view of FIG. 4 and for a cooling structure in which the cell's short side surface is in contact with an aluminum plate as shown in FIG. 2. These conditions are also shown in Table 1 below. Furthermore, for the example where the gap between cells was 0.5 mm, it was not necessary to measure the cooling capacity, as it was evident that it would result in a poor evaluation, so no evaluation was performed below.

[0133] ◇ Cooling Performance Evaluation (Temperature evaluation when abnormal heat generation occurs in cells)

[0134] A thermocouple was attached to an arbitrary location on the cell surface using Kapton tape, and the temperature rise accompanying charging and discharging was measured. An evaluation was performed on the combination of the example of the present invention and the comparative example (prior art) shown in Table 1. Using a module in which the above eight cells are connected, when the two central cells generate heat at a constant heat output of 500 kW / h under an environment of 25°C (simulating abnormal heat generation), the temperature of the adjacent cell at 2000 seconds after the start of heating was defined as the temperature of the hottest part among the three points measured at equal intervals in the height direction of the cell (at positions 20 mm, 50 mm, and 80 mm from the top). As a result, the case in which the temperature was lower than any case of the comparative example after 2000 seconds was designated as the example of the present invention. In addition, a case in which the temperature was higher than the comparative example was a multilayer structure of cell / aluminum plate / glass wool / aluminum plate / cell but the thickness of the aluminum plate was thin, was designated as a reference example.

[0135] In addition, as a result of the inventors' review, it was found that a change in characteristics begins to occur around 1,000 to 2,000 seconds after the start of measurement, and that behavior within this range is important for performance evaluation. It was also found that if 2,000 seconds after the start of measurement are exceeded, the characteristics become saturated and the performance of the battery cell is determined. Furthermore, assuming that the battery cell is installed in an electric vehicle, an early judgment is required because there is a need to secure time for occupants to evacuate when the battery cell is in a dangerous state. Based on these points, it was decided to make a judgment at 2,000 seconds after the start of measurement as described above.

[0136] In addition, the cooling performance of the present invention example, reference example, and comparative example was compared with the cell spacing for each cell spacing, based on Comparative Example 1 for a cell spacing of 5 mm, Comparative Example 4 for a cell spacing of 3 mm, and Comparative Example 6 for a cell spacing of 2 mm. For the comparison, the maximum cell temperature after 2000 seconds was compared and expressed as a battery temperature reduction rate according to the formula shown below.

[0137] Battery cell temperature reduction rate (%) (in the case of the present invention example)

[0138] = [(Maximum cell temperature of the reference comparative example - Maximum cell temperature of the present invention example) / Maximum cell temperature of the reference comparative example] × 100

[0139] Battery cell temperature reduction rate (%) (for reference examples)

[0140] =[(Maximum cell temperature of the standard comparison example - Maximum cell temperature of the reference example) / Maximum cell temperature of the standard comparison example] × 100

[0141] Battery cell temperature reduction rate (%) (in the case of the comparative example)

[0142] =[(Maximum cell temperature of reference comparison example - Maximum cell temperature of comparison example) / Maximum cell temperature of reference comparison example] × 100

[0143] In addition, the above temperature reduction rate was evaluated as follows: a score of "A" for 10% or more, a score of "B" for 5% or more but less than 10%, a score of "C" for 0% or more but less than 5%, and a score of "D" for 0% or less. Furthermore, a result showing superior performance compared to the case of a multilayer structure of cell / glass wool / aluminum plate / glass wool / cell (i.e., the above B structure) was rated as "Pass."

[0144]

[0145] [Comparison of Cooling Performance Results]

[0146] FIG. 13 shows the results when the distance between cells is 5.0 mm. Compared to Comparative Example 1 [insulating member 1.0 mm / Al 3.0 mm / insulating member 1.0 mm] and Comparative Example 2 [Al 5.0 mm only], the examples of the present invention, namely Example 1 [Al 1.5 mm / insulating member 2.0 mm / Al 1.5 mm], Example 2 [Al 2.25 mm / insulating member 0.5 mm / Al 2.25 mm], Example 3 [Al 2.0 mm / insulating member 1.0 mm / Al 2.0 mm], and Example 4 [Al 1.0 mm / insulating member 3.0 mm / Al 1.0 mm], all have a lower temperature of adjacent cells after 2000 seconds than the Comparative Examples. It can be seen that the examples of the present invention have higher cooling performance than the prior art. In addition, Reference Example 1 [Al 0.25 mm / insulation member 4.5 mm / Al 0.25 mm], in which the thickness of the aluminum plate is thin, showed a higher temperature of adjacent cells after 2000 seconds than Comparative Example 1, and the cooling performance was lower than that of the conventional technology. Also, although not shown in FIG. 13, in Invention Example 12 and Invention Example 13, in which the cell and the metal member were bonded with an adhesive using grease, and in Invention Example 14, in which the insulation member was changed to glass wool to form a refractory cloth, the cooling performance was higher than that of the conventional technology.

[0147] Figure 14 shows the results when the distance between cells is 3 mm. Compared to Comparative Example 3 [insulating member 1.0 mm / Al 1.0 mm / insulating member 1.0 mm], Comparative Example 4 [insulating member 0.5 mm / Al 2.0 mm / insulating member 0.5 mm], and Comparative Example 5 [Al 3.0 mm only], it can be seen that in the present invention examples 5 [Al 0.5 mm / insulating member 2.0 mm / Al 0.5 mm] and 6 [Al 1.0 mm / insulating member 1.0 mm / Al 1.0 mm], the temperature of adjacent cells after 2000 seconds is lower than in any of the comparative examples, and the cooling performance is higher than that of the prior art.

[0148] Figure 15 shows the results when the distance between cells is 2 mm. Compared to Comparative Example 6 [insulating member 0.5 mm / Al 1.0 mm / insulating member 0.5 mm] and Comparative Example 7 [Al 2.0 mm only], it can be seen that in the present invention example 7 [Al 0.5 mm / insulating member 1.0 mm / Al 0.5 mm], the temperature of adjacent cells after 2000 seconds is lower than in any of the comparative examples, and the cooling performance is higher than that of the prior art.

[0149] FIG. 16 shows the results of Example 8 of the present invention (in which the lower portions of two aluminum plates are connected in the height direction at 25% and formed as a single unit in [Al 1.5mm / insulating member 2.0mm / Al 1.5mm], in the case where the lower portions of the metal members are connected (U-shaped metal members) at a cell spacing of 5mm (structure of FIG. 4), compared with Example 1 and Comparative Example 1. In Example 8 of the present invention, the temperature of adjacent cells after 2000 seconds is slightly higher than in Example 1, but lower than in Comparative Example 1, and it can be seen that the cooling performance is higher than that of the prior art.

[0150] FIG. 17 shows a comparison between Example 9 of the present invention ([Al 1.5mm / insulating member 2.0mm / Al 1.5mm]+Al provided on the side of the short side) and Example 1 of the present invention, in which an aluminum plate (3mm thick) is attached to the side of all short sides of 8 battery cells using grease and the entire side of the battery module is covered with an aluminum plate (structure of FIG. 2). It can be seen that in Example 9 of the present invention, the temperature of adjacent cells after 2000 seconds is lower than in Example 1 of the present invention, and the cooling performance is also higher.

[0151] As is clear from Table 1 and Figures 13 to 17 above, all of the examples corresponding to the present invention are rated "A" or "B", and it can be seen that they have superior cooling capabilities compared to the prior art.

[0152] [Regarding the influence of the type of plate-shaped metal member (thermal conductivity)]

[0153] Figure 18 shows the results when the metal member is changed to duralumin (thermal conductivity: 110 W / m·K at room temperature) and cast iron (thermal conductivity: 50 W / m·K at room temperature).

[0154] Example 10 of the present invention was carried out under the same conditions as Example 1, except that the metal member was made of duralumin, and Comparative Example 8 was carried out under the same conditions as Comparative Example 1, except that the metal member was made of duralumin. When comparing the two, it can be seen that Example 10 of the present invention, compared to Comparative Example 8, has a lower temperature of adjacent cells after 2000 seconds and has higher cooling performance than the prior art. However, compared to Example 1 of the present invention, the temperature of Example 10 of the present invention has risen overall, and it can be seen that the thermal conductivity of the metal member is preferably 150 W / m·K or higher.

[0155] In addition, Reference Example 2 was conducted under the same conditions as Example 1, except that the metal member was made of cast iron, and Comparative Example 9 was conducted under the same conditions as Comparative Example 1, except that the metal member was made of cast iron. When comparing the two, Reference Example 2 shows a lower temperature of adjacent cells after 2000 seconds compared to Comparative Example 9, but the maximum temperature of adjacent cells exceeds 200°C. Therefore, it cannot be said that the temperature rise of adjacent battery cells can be effectively suppressed, and thus it is considered a reference example.

[0156] [On the influence of the type of insulating material (thermal conductivity) in the insulation layer]

[0157] Figure 19 shows the results when the insulating member of the insulating layer is changed to a glass plate (thermal conductivity: 0.9 W / m·K at room temperature).

[0158] Example 11 of the present invention was carried out under the same conditions as Example 1, except that the insulating member was made of a glass plate, and Comparative Example 10 was carried out under the same conditions as Comparative Example 1, except that the insulating member was made of a glass plate. When comparing the two, it can be seen that Example 11 of the present invention, compared to Comparative Example 10, has a lower temperature of adjacent cells after 2000 seconds and has higher cooling performance than the prior art. However, compared to Example 1 of the present invention, the temperature of Example 10 of the present invention rises overall, and it can be seen that the thermal conductivity of the insulating member is preferably 0.1 W / m·K or less.

[0159] Although suitable embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to these examples. It is obvious to those skilled in the art that various modifications or alterations can be made within the scope of the technical concept described in the claims, and these are also naturally understood to fall within the technical scope of the present invention. Explanation of the symbols

[0160] 1: Battery cell cooling structure 2: Duplex structure 10: Battery cell 20: Plate-shaped metal member 30: Insulation layer (insulating member or gas layer) 40: Cooling element 41: Cooling plate 42: Heated Sheet 50: Heated Sheet 60: Second plate-shaped metal member 70: Third plate-shaped metal member 100: Battery module

Claims

Claim 1 A cooling structure between adjacent battery cells in a plurality of prismatic battery cells arranged side by side with two sides facing each other, wherein the adjacent battery cells form a multilayer structure of battery cell / plate-shaped metal member / insulating layer / plate-shaped metal member / battery cell by means of: a plate-shaped metal member having a thermal conductivity of 100 W / m·K or more and a thickness of 0.3 mm or more and thermally contacting each opposing side of the adjacent battery cells; and an insulating layer having at least one of an insulating member or a gas layer disposed between the plate-shaped metal members thermally contacting each opposing side of the adjacent battery cells, having a thermal conductivity of 1.0 W / m·K or less and a thickness of 0.5 mm or more; and further comprising a cooling member thermally contacting each of the plurality of prismatic battery cells or existing in the vicinity of each of the plurality of prismatic battery cells, wherein each of the plate-shaped metal members has at least one end that is thermally contacted by the cooling member A cooling structure between battery cells, wherein two plate-shaped metal members constituting the above-described multilayer structure are in contact, and the two plate-shaped metal members have the same thermal conductivity and thickness, and the ratio of the thickness of the plate-shaped metal member / insulating layer / plate-shaped metal member is 1.0:0.2 to 4.0:1.0, and the plate-shaped metal members are formed into a concave shape by connecting the lower portions of the plate-shaped metal members that are in thermal contact with each side of the adjacent insulating member, and the concave-shaped plate-shaped metal members are inserted between the adjacent insulating members, and the battery cell is disposed in the concave portion of the concave shape. Claim 2 A cooling structure between adjacent battery cells in a plurality of prismatic battery cells arranged side by side with two sides facing each other, wherein the adjacent battery cells form a multilayer structure of battery cell / plate-shaped metal member / insulating layer / plate-shaped metal member / battery cell by means of: a plate-shaped metal member having a thermal conductivity of 100 W / m·K or more and a thickness of 0.3 mm or more and thermally contacting each opposing side of the adjacent battery cells; and an insulating layer having at least one of an insulating member or a gas layer disposed between the plate-shaped metal members thermally contacting each opposing side of the adjacent battery cells, having a thermal conductivity of 1.0 W / m·K or less and a thickness of 0.5 mm or more; and further comprising a cooling member thermally contacting each of the plurality of prismatic battery cells or existing in the vicinity of each of the plurality of prismatic battery cells, wherein each of the plate-shaped metal members has at least one end that is thermally contacted by the cooling member A cooling structure between battery cells, wherein two plate-shaped metal members constituting the multilayer structure are in contact, and the two plate-shaped metal members have the same thermal conductivity and thickness, and the ratio of the thickness of the plate-shaped metal member / insulating layer / plate-shaped metal member is 1.0:0.2 to 4.0:1.0, and the plate-shaped metal member is processed to have a concave cross-sectional shape and is inserted between adjacent battery cells, and the insulating layer is disposed in the concave portion of the concave shape. Claim 3 A cooling structure between battery cells according to claim 1 or 2, wherein the side of the battery cell is composed of a steel material, and when the thermal resistance at the contact interface between the battery cell and the plate-shaped metal member is Rs and the thermal resistance of the plate-shaped metal member is Rm, Rs / Rm ≤ 3.

0. Claim 4 A cooling structure between battery cells according to claim 1 or 2, wherein the thickness of the plate-shaped metal member is 0.5 mm or more and the thickness of the insulation layer is 1.0 mm or more. Claim 5 A cooling structure between battery cells according to claim 1 or 2, wherein in each of the plurality of prismatic battery cells, on a side parallel to the direction in which the plurality of prismatic battery cells are arranged side by side, a second plate-shaped metal member having a thermal conductivity of 100 w / m·K or more and a thickness of 0.3 mm or more is also present, and the second plate-shaped metal member is in thermal contact with the side of the battery cell and at least one end is in thermal contact with the cooling member. Claim 6 A cooling structure between battery cells according to claim 1 or 2, wherein the spacing between adjacent battery cells is 1.5 to 5.0 mm. Claim 7 A cooling structure between battery cells according to claim 1 or 2, wherein the plate-shaped metal member and the cooling member are in thermal contact through an adhesive or grease having a thermal conductivity of 1.0 W / m·K or higher. Claim 8 In claim 7, the cooling structure between battery cells, wherein the adhesive or grease having a thermal conductivity of 1.0 W / m·K or higher is an adhesive or grease that cures at room temperature. Claim 9 A cooling structure between battery cells according to claim 1 or 2, wherein the cooling member is provided with a groove, and the plate-shaped metal member is fitted into the groove. Claim 10 In claim 1 or 2, the prismatic battery cell is a cooling structure between battery cells formed by stacking laminated battery cells. Claim 11 A cooling structure between battery cells according to claim 1 or 2, wherein the material of the plate-shaped metal member is at least any of aluminum, aluminum alloy, copper, or copper alloy. Claim 12 A battery module having a cooling structure between battery cells as described in paragraph 1 or 2. Claim 13 A battery pack having a cooling structure between battery cells as described in paragraph 1 or 2. Claim 14 delete

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