Secondary battery module

Abstract

To provide a secondary battery module that can suppress a decrease in cooling efficiency even when vibration or impact is applied by an external force.SOLUTION: A secondary battery module includes an assembled battery including battery cells each having a negative electrode current collector, a negative electrode composition layer, a separator, a positive electrode composition layer, and a positive electrode current collector, in that order, and an exterior body that houses a plurality of battery cells, and a cooler formed of a resin member, and both the assembled battery and the cooler are elastic and the cooler has a different elastic modulus from that of the assembled battery, and the assembled battery and the cooler are stacked in layers.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a secondary battery module. [Background technology]

[0002] BACKGROUND ART Secondary batteries such as lithium ion secondary batteries that can be repeatedly charged and discharged are widely used in various technical fields such as mobile phones, personal computers, electric vehicles, hybrid vehicles, and on-board power storage devices.

[0003] In such secondary batteries, there is a risk that a rise in battery temperature will cause a decrease in battery performance, so it is known that the temperature rise is suppressed by cooling the battery, etc. A battery system has been disclosed in which a heat transfer portion is provided adjacent to an electrode group (2), the heat transfer portion being formed of a corrugated member (3) and a fluid path wall (4) that are fluid paths through which a heat transfer medium or a refrigerant flows, and the electrode group (2) is heated or cooled by circulating the heat transfer medium or the refrigerant depending on the usage situation (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4361229 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the technology described in Patent Document 1, because the heat transfer medium that functions as a cooler when the refrigerant flows is rigid, there is a risk that the heat transfer medium as a cooler may mechanically crack and become ineffective when subjected to large vibrations during vehicle operation, transportation of the secondary battery, or earthquakes when placed on a surface. Also, although the electrode group (2) and the heat transfer medium must be in surface contact, vibrations or impacts applied to the secondary battery by external forces may cause the electrode group (2) and the rigid heat transfer medium to separate, resulting in a risk of reduced cooling efficiency.

[0006] An object of the present invention is to provide a secondary battery module that can suppress a decrease in cooling efficiency even when vibration or impact is applied by an external force. [Means for solving the problem]

[0007] The secondary battery module of the present invention includes an assembled battery including battery cells each having a negative electrode current collector, a negative electrode composition layer, a separator, a positive electrode composition layer, and a positive electrode current collector in that order, and an exterior body that houses a plurality of battery cells; and a cooler formed of a resin member, wherein both the assembled battery and the cooler are elastic and the cooler has a different elastic modulus from that of the assembled battery, and the assembled battery and the cooler are stacked in layers. [Effects of the Invention]

[0008] According to the present invention, in the secondary battery module, the cooler has elasticity and a different elastic modulus from that of the battery pack, so that the cooler as a whole functions as a damper, and even when vibrations or shocks are applied by external forces, the cooler does not mechanically break and quickly absorbs the vibrations or shocks. As a result, the cooler is less likely to break mechanically and the battery pack and the cooler remain in close contact with each other, making it possible to suppress a decrease in the cooling effect. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view schematically showing a battery pack according to an embodiment of the present invention; [Figure 2] 1 is a perspective view schematically showing a secondary battery module according to an embodiment of the present invention; [Figure 3] FIG. 10 is a perspective view schematically showing a modified example of the cooler. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention (the present embodiment) will be described with reference to the drawings. In this specification, the same reference numerals are used for similar components in the drawings. Furthermore, the dimensional ratios in the drawings may be exaggerated for the sake of explanation and may differ from the actual ratios. Furthermore, a plan view indicates that the object is viewed from the stacking direction of the secondary battery cells. Furthermore, "and / or" means at least one of the following; for example, "X and / or Y" means X only, Y only, or X and Y. Unless otherwise specified, the materials exemplified in the following embodiments and modifications can be used alone or in combination of two or more.

[0011] <Battery pack> A battery pack according to this embodiment will be described. FIG. 1 is a cross-sectional view schematically showing a secondary battery (battery pack 100) according to this embodiment. The battery pack 100 has a rectangular parallelepiped shape. The battery pack 100 is used in the form of a modular battery pack formed by combining a plurality of secondary battery cells (hereinafter simply referred to as battery cells). As shown in FIG. 1, the battery pack 100 includes four layers of stacked secondary battery cells (battery cells 5), a high-voltage tab 50, and an exterior body 60. While the example shows a case in which a plurality of battery cells 5 (four layers in this example) are stacked, the number of stacked battery cells 5 may be a single one. The number of stacked battery cells 5 is determined appropriately taking into consideration battery performance such as the required battery capacity. Below, an example will be described in which the battery pack 100 according to this embodiment is configured as a lithium-ion secondary battery.

[0012] <Battery cell> The battery cell 5 will now be described. As shown in FIG. 1, the battery cell 5 has a rectangular parallelepiped shape. The battery cell 5 includes a positive electrode 1, a negative electrode 2, a separator 30, and a frame 40. The positive electrode 1 includes a positive electrode current collector 10 and a positive electrode composition layer 11 disposed on the lower surface of the positive electrode current collector 10 in the figure (the surface (first surface) facing the negative electrode 2). The negative electrode 2 includes a negative electrode current collector 20 and a negative electrode composition layer 21 disposed on the upper surface of the negative electrode current collector 20 in the figure (the surface (second surface) facing the positive electrode 1). The battery cell 5 is arranged so that the positive electrode composition layer 11 and the negative electrode composition layer 21 face each other with the separator 30 interposed therebetween, and the positive electrode 1, separator 30, and negative electrode 2 are stacked in this order from the top in FIG. 1.

[0013] The positive electrode current collector 10 has a rectangular shape in a plan view and is a resin current collector (resin current collector) made of a conductive polymer material, which is a conductive resin. The conductive polymer material of the resin current collector can be, for example, a matrix resin to which a conductive agent is added as needed. The conductive agent constituting the conductive polymer material can be, for example, a conductive additive similar to that contained in the coating material that coats the positive electrode active material. The positive electrode current collector 10 may further contain a dispersant for the resin current collector. The surface of the positive electrode current collector 10 may be appropriately metal-plated. The surface of the positive electrode current collector 10 includes a coated portion where the positive electrode composition layer 11 is disposed and an uncoated portion where the positive electrode composition layer 11 is not disposed. This uncoated portion also forms the peripheral portion of the surface of the positive electrode current collector 10.

[0014] The negative electrode current collector 20 is a resin current collector having a rectangular shape in a plan view and containing a conductive resin, which is a conductive polymer material. The conductive polymer material of the resin current collector can be, for example, a matrix resin to which a conductive agent is added as needed. The conductive agent constituting the conductive polymer material can be, for example, a conductive additive similar to that contained in the coating material that coats the negative electrode active material. The negative electrode current collector 20 may further contain a dispersant for the resin current collector. The surface of the negative electrode current collector 20 may be appropriately metal-plated. The surface of the negative electrode current collector 20 has a coated portion where the negative electrode composition layer 21 is disposed and an uncoated portion where the negative electrode composition layer 21 is not disposed. This uncoated portion also forms the peripheral portion of the surface of the negative electrode current collector 20. Hereinafter, the positive electrode current collector 10 and the negative electrode current collector 20 will also be referred to simply as electrode current collectors.

[0015] The matrix resin constituting the conductive polymer material is preferably polyolefin, and more preferably at least one selected from the group consisting of polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), and polycycloolefin (PCO) from the viewpoint of electrical stability.

[0016] When a resin current collector is constructed by adding a conductive agent to a matrix resin, the conductive agent is composed of a conductive filler. Examples of conductive fillers include metals (nickel, aluminum, stainless steel (SUS), silver, copper, titanium, etc.), carbon-based materials (graphite and carbon black (acetylene black, ketjen black, furnace black, channel black, thermal lamp black, etc.)), and mixtures thereof. Among these, carbon-based materials are preferred. Using a carbon-based conductive filler can prevent metals from the negative electrode current collector 20 and the positive electrode current collector 10 from being mixed into the negative electrode active material and the positive electrode active material. This can particularly suppress characteristic degradation in the positive electrode active material.

[0017] Such conductive fillers may be used alone or in combination of two or more. The conductive filler may be an alloy or metal oxide of the above-mentioned metals. The conductive filler may be a particulate ceramic material or a resin material coated with a conductive material such as the above-mentioned metals by plating or the like.

[0018] The positive electrode composition layer 11 has a rectangular shape in a plan view and contains a positive electrode active material. Examples of the positive electrode active material include composite oxides of lithium and transition metals. Examples of the lithium transition metal composite oxides include composite oxides containing one type of transition metal (e.g., LiCoO2, LiNiO2, LiAlMnO4, LiMnO2, and LiMn2O4), composite oxides containing two types of transition metal elements (e.g., LiFeMnO4, LiNi 1-x Co x O2, LiMn 1-y Co y O2, LiNi 1 / 3 Co 1 / 3 Al 1 / 3 O2 and LiNi 0.8 Co 0.15 Al 0.05 O2) and complex oxides containing three or more metal elements [e.g., LiM a M' b M'' c O2 (M, M' and M'' are different transition metal elements, and a + b + c = 1. For example, LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 Examples of the lithium-containing transition metal phosphate include lithium-containing transition metal phosphates (e.g., LiFePO4, LiCoPO4, LiMnPO4, and LiNiPO4), transition metal oxides (e.g., MnO2 and VO5), transition metal sulfides (e.g., MoS2 and TiS2), and conductive polymers (e.g., polyaniline, polypyrrole, polythiophene, polyacetylene, poly-p-phenylene, and polyvinylcarbazole). The positive electrode active material may be a combination of two or more of the lithium-transition metal composite oxides described above. The lithium-containing transition metal phosphate may have some of the transition metal sites substituted with other transition metals.

[0019] In addition to the positive electrode active material, the positive electrode composition layer 11 may contain a coating resin, a conductive additive such as metal or carbon, an electrolyte solution containing an electrolyte salt, etc. The positive electrode active material may be coated with a coating material containing a coating resin and a conductive additive. Furthermore, the positive electrode composition layer 11 may or may not contain conductive fibers such as carbon fibers.

[0020] The negative electrode composition layer 21 has a rectangular shape in a plan view and includes a negative electrode active material. Examples of the negative electrode active material include carbon-based materials [graphite, hard carbon (non-graphitizable carbon), amorphous carbon, baked resins (e.g., baked and carbonized phenolic resins, furan resins, etc.), cokes (e.g., pitch coke, needle coke, petroleum coke, etc.), and carbon fibers], silicon-based materials [silicon, silicon oxide (SiOx), silicon-carbon composites (carbon particles whose surfaces are coated with silicon and / or silicon carbide, silicon particles or silicon oxide particles whose surfaces are coated with carbon and / or silicon carbide, silicon carbide, etc.], and silicon alloys (silicon- Examples of the conductive material include aluminum alloys, silicon-lithium alloys, silicon-nickel alloys, silicon-iron alloys, silicon-titanium alloys, silicon-manganese alloys, silicon-copper alloys, and silicon-tin alloys), conductive polymers (e.g., polyacetylene and polypyrrole), metals (e.g., tin, aluminum, zirconium, and titanium), metal oxides (e.g., titanium oxide and lithium-titanium oxide), and metal alloys (e.g., lithium-tin alloys, lithium-aluminum alloys, and lithium-aluminum-manganese alloys), as well as mixtures of these with carbon-based materials.

[0021] The negative electrode composition layer 21 may contain, in addition to the negative electrode active material, a coating resin, a conductive additive such as metal or carbon, an electrolyte solution containing an electrolyte salt, and the like. The negative electrode active material may be coated with a coating material containing a coating resin and a conductive additive. The negative electrode composition layer 21 may or may not contain conductive fibers such as carbon fibers. Hereinafter, the positive electrode composition layer 11 and the negative electrode composition layer 21 will also be simply referred to as electrode composition layers.

[0022] The separator 30 has a rectangular shape in a plan view, and may be, for example, a porous sheet made of polymer or fiber that absorbs and retains an electrolytic solution or a gel polymer electrolyte, etc. A nonwoven fabric separator may also be used.

[0023] The frame 40 is annular in plan view and is provided between the peripheral edge of the surface of the positive electrode current collector 10 and the peripheral edge of the surface of the negative electrode current collector 20. The frame 40 is arranged so as to cover the side surface of the positive electrode composition layer 11 and the side surface of the negative electrode composition layer 21. The frame 40 may be made of any material that is durable against the electrolyte, and a thermosetting polymer material is preferred. An example of a thermosetting polymer material is an epoxy resin, which is highly durable and easy to handle. Although not shown in the cross-sectional view of FIG. 1, the frame 40 extends in the front-to-rear direction (depth direction) and left-to-right direction of FIG. 1.

[0024] The battery pack 100 also includes a high-voltage tab 50. The high-voltage tab 50 is, for example, a substantially plate-shaped metal member (e.g., copper). The high-voltage tab 50 is in surface contact with part of the current collectors of the battery cells 5 located in the bottom and top layers, and is used to extract current from the stacked battery cells 5. The current collectors with which the high-voltage tab 50 is in surface contact are also the current collectors of the outermost layers.

[0025] The battery pack 100 also includes an exterior body 60. The exterior body 60 houses the battery cells 5 and prevents the intrusion of liquids such as water present outside the exterior body 60. The exterior body 60 can be, for example, an aluminum laminate film or aluminum laminate sheet in which a metal material such as aluminum is coated with an insulating material. The battery cells 5 are placed on the exterior body 60, and the top and side surfaces of the battery cells 5 are further covered and sealed by the exterior body 60, thereby suitably housing the battery cells 5 in the exterior body 60. The pressure inside the exterior body 60 is reduced relative to atmospheric pressure. Here, atmospheric pressure refers to standard atmospheric pressure (101.325 kPa).

[0026] The materials of the components of the battery pack 100 are not limited to the above materials, and various materials can be used.

[0027] <Secondary battery module> FIG. 2 is a perspective view schematically illustrating a secondary battery module according to this embodiment. The secondary battery module 500 includes a battery pack 100 and coolers 200 and 201. The cooler 200 is disposed so that its bottom surface (the back surface facing the battery pack 100) is in contact with the top surface (the front surface facing the cooler 200) of the battery pack 100. The cooler 201 is disposed so that its top surface (the front surface facing the battery pack 100) is in contact with the bottom surface (the back surface facing the cooler 201) of the battery pack 100. The coolers 200 and 201 will be described in detail below, but because the cooler 201 is the same member as the cooler 200, its description will be omitted and only the cooler 200 will be described in detail. Note that the high-voltage tab 50 of the battery pack 100 is not shown in the drawing.

[0028] <Cooler> The cooler 200 has a rectangular parallelepiped shape. The cooler 200 is a member made of a resin material. The cooler 200 has a back surface that is the surface that contacts the front surface of the battery pack 100, a front surface that is the surface opposite the back surface, and side surfaces that are adjacent to the back surface and the front surface. The side surfaces have a first side surface that is the surface adjacent to the long sides of the back surface and the front surface, a second side surface that is the surface opposite the first side surface, a third side surface that is the surface adjacent to the short sides of the back surface and the front surface, and a fourth side surface that is the surface opposite the third side surface.

[0029] The cooler 200 has a plurality of through holes therein. The through holes are linear tubes extending from the third side surface to the fourth side surface of the cooler 200. The leading end of each through hole is located on the third side surface, and the trailing end of each through hole is located on the fourth side surface. The plurality of through holes are arranged at equal intervals inside the cooler 200, on the third side surface, and on the fourth side surface. The plurality of through holes have the same length. The cooler 200 may have a single through hole therein, in which case it may be wide. A cooling fluid flows through the through holes of the cooler 200. Examples of the cooling fluid include a cooling liquid such as water and a cooling gas such as air. The cooling fluid may be selected appropriately depending on the conditions, environment, cost, etc., in which the battery pack 100 and the secondary battery module 500 are used.

[0030] Either an air-cooling system or a liquid-cooling system may be selected depending on the conditions, environment, cost, and other factors for using the battery pack 100 and the secondary battery module 500. For example, if a liquid-cooling system is selected for a large-scale secondary battery module for stationary use, a circulation mechanism may be provided that repeatedly allows a cooling liquid, such as low-temperature water, to pass through the cooler, and then cools the heated cooling liquid down to a low temperature after passing through the cooler, allowing it to be reintroduced. In the case of an air-cooling system, the battery pack 100 must be exposed to the surrounding air, and it is preferable to forcibly ventilate it with a fan or the like. Alternatively, both air-cooling and liquid-cooling systems may be used.

[0031] The battery pack 100 has elasticity because it includes components made of a resin material, such as electrode current collectors and a frame. The cooler 200 is also made of a resin material and has elasticity, so the entire secondary battery module 500 has elasticity. In this embodiment, the cooler 200 has a different modulus of elasticity from that of the battery pack 100. When comparing the modulus of elasticity of the battery pack 100 and the cooler 200, the cooler 200 has a higher modulus of elasticity or a lower modulus of elasticity. The resin material of the cooler 200 contains flexible epoxy resin, and examples thereof include EPICLON (registered trademark), manufactured by DIC Corporation.

[0032] If the cooler 200 is elastic and has a different elastic modulus from that of the battery pack 100, even if vibrations or shocks are applied to the secondary battery module 500 due to external forces, the cooler 200 can quickly absorb the vibrations and shocks without mechanically breaking. That is, because the cooler 200 as a whole functions as a damper, even if a natural vibration of, for example, 10 to 20 Hz is applied, the vibrations can be quickly absorbed. Furthermore, even during such vibrations, the elastic battery pack 100 and the cooler 200 maintain a state of close contact with each other, so that gaps are unlikely to occur between them (the two are unlikely to separate), and this configuration can suppress a decrease in the cooling effect.

[0033] In this way, the secondary battery module includes at least one battery cell having, in order, a negative electrode current collector, a negative electrode composition layer, a separator, a positive electrode composition layer, and a positive electrode current collector, an exterior body that houses the at least one battery cell, an elastic secondary battery, and an elastic cooler, the cooler being formed from a resin member having a different elastic modulus from that of the secondary battery, and the secondary battery and the cooler being stacked in layers.

[0034] <Modification> FIG. 3 is a perspective view schematically illustrating a modified example of the cooler. During use, the central portion of the battery pack 100 becomes hotter than the outer periphery of the battery pack 100. To cool the central portion of the battery pack 100, the through-holes of the cooler 200 are serpentine in plan view. The front and rear ends of the through-holes of the cooler 200 are equally spaced on the third and fourth side surfaces of the cooler 200, as in the above embodiment, and the central portions of the through-holes are densely packed toward the center (inward) of the cooler relative to the positions of the front and rear ends. Specifically, the through-holes of the cooler 200 are gradually inclined from the front end located on the third side surface toward the center, with the angle peaking at the center. Furthermore, the through-holes of the cooler 200 are inclined from the center toward the rear end located on the fourth side surface, such that the angle decreases. The through-holes of the cooler 200 are thus serpentine.

[0035] Furthermore, since the cooler 200 has a plurality of through holes, the inclination angle differs for each through hole. That is, the inclination angle for each through hole differs depending on the positions of the leading and trailing ends of the through holes arranged on the third and fourth side surfaces of the cooler 200. If the leading and trailing ends of the through holes are located toward the center on the third and fourth side surfaces, the inclination angle is small, i.e., the degree of meandering is small. If the leading and trailing ends of the through holes are located toward the outer periphery on the third and fourth side surfaces, the inclination angle is large, i.e., the degree of meandering is large. In this way, a structure may be formed that actively cools the center of the battery pack 100.

[0036] Furthermore, in the cooler 200, when the plurality of through holes are linear, the through holes have the same length, but when the through holes are serpentine, they do not have to have the same length. For example, in the third and fourth side faces of the cooler 200, the through holes whose leading and trailing ends are located on the outer periphery may have a longer inclined length than the through holes whose leading and trailing ends are located on the central side.

[0037] Furthermore, although the cooler 200 is in direct contact with the battery pack 100 in the above embodiment, it may be in contact via an adhesive to improve adhesion. It may also be in contact via heat dissipation grease or the like to improve cooling efficiency. It may also be in contact via a material that can achieve both improved adhesion and improved cooling efficiency.

[0038] Furthermore, two coolers 200, 201 are provided to be disposed on the front and back surfaces of the battery pack 100, but the number is not particularly limited. If a sufficient cooling effect can be expected with the provision of either one of the coolers 200, 201, only one may be provided. Furthermore, the coolers may be provided on each side surface of the battery pack 100; for example, four coolers may be provided, one on each side surface of the battery pack 100.

[0039] <When used in vehicles> Assume that the secondary battery module 500 according to this embodiment is used in a vehicle. For example, a coolant may be used as the cooling medium circulating through the cooler. Examples of known coolant include those containing ethylene glycol as the main component and other ingredients such as rust inhibitors and dyes. Examples of cooling systems using such coolant include those in which the coolant flows through a cooler to cool the engine and battery inside the vehicle, then passes the heated coolant through a radiator, where it dissipates heat to the surroundings and is cooled, and then circulates back to the engine and battery. In this manner, the secondary battery module 500 according to this embodiment can also be used in a vehicle.

[0040] As described above, the secondary battery and secondary battery module according to the present embodiment have been described. However, it goes without saying that those skilled in the art can appropriately add, modify, or omit aspects of the present embodiment within the scope of the technical concept thereof. For example, although the secondary battery has been described as being elastic, a rigid secondary battery may also be used.

[0041] The secondary battery has been described as a lithium-ion battery. However, other secondary batteries, such as lead-acid batteries, all-solid-state batteries, semi-solid-state batteries, and nickel-metal hydride batteries, may also be used. For example, a battery cell of an all-solid-state lithium-ion battery uses a solid electrolyte instead of the liquid electrolyte. This battery cell does not require a separator 30, and is filled with a solid electrolyte from the positive electrode 1 to the negative electrode 2. The positive electrode composition layer 11 is in a state where a positive electrode active material is interposed within this solid electrolyte. The negative electrode composition layer 21 is in a state where a negative electrode active material is interposed within this solid electrolyte. The details and materials of each component constituting this battery cell are the same as those of the respective components constituting the battery cell 5 according to this embodiment. [Industrial Applicability]

[0042] The secondary battery and secondary battery module according to the present embodiment can be used in, for example, an electric vehicle or a hybrid vehicle to achieve a long driving distance per charge and a long life. Furthermore, a long life can also be achieved when used in other applications such as a stationary power storage device. [Explanation of symbols]

[0043] 1 positive electrode 2 negative electrode 5 battery cells 10 Positive electrode current collector 11 Positive electrode composition layer 20 Negative electrode current collector 21 Negative electrode composition layer 30 Separator 40 Frame 50 High Voltage Tab 60 Exterior body 100 battery packs (lithium ion batteries) 200 cooler 201 Cooler 500 Secondary Battery Module

Claims

1. a battery pack including a battery cell having a negative electrode current collector, a negative electrode composition layer, a separator, a positive electrode composition layer, and a positive electrode current collector in that order, and an exterior body that houses a plurality of the battery cells; a cooler formed of a resin member, the battery pack and the cooler both have elasticity, and the cooler has an elastic modulus different from that of the battery pack; The battery pack and the cooler are stacked in layers. Secondary battery module.

2. The cooler has a rectangular parallelepiped shape, the cooler has a through-hole extending from one opposing side surface to the other opposing side surface therein and through which a cooling fluid flows; The through holes are linear. The secondary battery module according to claim 1 .

3. the cooler has a plurality of the through holes, the through holes are arranged closer to a center of the cooler with respect to the positions of the front and rear ends of the through holes on the one and the other side surfaces of the cooler, so as to be densely packed together. The secondary battery module according to claim 2 .

4. the angle at which the through holes are inclined is small when the positions of the front and rear ends of the through holes on the one and the other side surfaces of the cooler are closer to the center, and the angle at which the through holes are inclined is large when the positions of the front and rear ends are closer to the outer periphery; The secondary battery module according to claim 3 .

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