Secondary battery module

Abstract

To provide a secondary battery module that includes a strong case and can suppress the deterioration of battery performance due to gas generation.SOLUTION: A secondary battery module includes a 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, and an exterior body that houses the battery cell, wherein the battery cell has a structure that allows gas generated inside to be released, and the exterior body is a polymer resin compound produced by a chemical reaction between isocyanate and an amine group.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] 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 stationary power storage devices. For example, a lithium-ion secondary battery module includes an electrode assembly in which a positive electrode and a negative electrode are stacked, and a case that houses the electrode assembly. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6107516 Summary of the Invention [Problem to be solved by the invention]

[0004] In such secondary battery modules, there is a need for improved safety in the event that a sharpened conductive member such as a nail (hereinafter referred to as a "nail") is inserted into the case from outside. For example, Patent Document 1 discloses that an insulating film containing aramid fibers is disposed between the case and the electrode assembly in the stacking direction of the positive and negative electrodes, thereby preventing the nail from traveling through the insulating film and reaching the electrode assembly. However, while the technology described in Patent Document 1 can improve safety to a certain extent compared to conventional cases, there remains a problem in terms of toughness.

[0005] An object of the present invention is to provide a secondary battery module that has a strong case and is capable of suppressing deterioration of battery performance due to gas generation. [Means for solving the problem]

[0006] The present inventors have conducted extensive research based on the above findings and have come up with the following aspects of the invention. The secondary battery module of the present invention is a secondary battery comprising a 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, and an exterior body that houses the battery cell, wherein the battery cell has a structure that allows it to release gas generated inside, and the exterior body is a polymer resin compound produced by a chemical reaction between isocyanate and an amine group. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a secondary battery module that has a strong case and is capable of suppressing deterioration of battery performance due to gas generation. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view schematically showing a secondary battery module according to an embodiment of the present invention. [Figure 2] 1 is a perspective view schematically illustrating a gas discharge portion and a secondary battery module including the gas discharge portion according to an embodiment of the present invention. [Figure 3] FIG. 10 is a perspective view schematically showing a secondary battery cell according to a modified example of the embodiment of the present invention. [Figure 4] FIG. 10 is a cross-sectional schematic view showing a flow path (space) according to a modified example of the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, various embodiments of the present invention (the present embodiment) will be described with reference to the drawings. Note that 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 convenience of explanation and may differ from the actual ratios. Furthermore, a plan view indicates that an object is viewed from the thickness direction of a secondary battery. A cross-sectional view indicates that a cross section obtained by cutting a secondary battery in its thickness direction is viewed from a direction perpendicular to the cross section. A peripheral portion indicates a region having a predetermined width extending inward from the periphery of an object such as a secondary battery cell, a current collector, or a composition layer. Furthermore, "and / or" means at least one of the following; for example, "X and / or Y" means X only, Y only, or both X and Y.

[0010] <Secondary battery> A secondary battery according to this embodiment will be described. FIG. 1 is a cross-sectional view schematically showing the secondary battery according to this embodiment. A secondary battery module 100 is, for example, a battery pack formed by combining a plurality of secondary battery cells (hereinafter simply referred to as battery cells) into a module. As shown in FIG. 1, the secondary battery module 100 includes four layers of stacked secondary battery cells (battery cells 5), a high-voltage tab 50, and an exterior body 60. While a case in which a plurality of battery cells 5 (four layers here) are stacked is illustrated, the number of stacked battery cells 5 may be a single cell. The number of stacked battery cells 5 is determined appropriately taking into consideration battery performance such as the required battery capacity. The secondary battery module 100 is, for example, a lithium-ion secondary battery. Below, an example in which the secondary battery module 100 according to this embodiment is configured as a lithium-ion secondary battery will be described.

[0011] The battery cell 5 will now be described. As shown in FIG. 1, the battery cell 5 has an overall rectangular parallelepiped shape and 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 (front surface (first surface)) of the positive electrode current collector 10 in the figure. The negative electrode 2 includes a negative electrode current collector 20 and a negative electrode composition layer 21 disposed on the upper surface (front surface (second surface)) of the negative electrode current collector 20 in the figure. 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.

[0012] The positive electrode current collector 10 has a rectangular shape in a plan view and is a resin current collector (resin current collector) 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 suitably be, for example, the same conductive additive as that contained in the coated positive electrode active material. The positive electrode current collector 10 may further contain a dispersant for the resin current collector. The positive electrode current collector 10 has a surface facing the negative electrode 2. The surface of the positive electrode current collector 10 may be appropriately metal-plated. The surface of the positive electrode current collector 10 has 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.

[0013] The negative electrode current collector 20 has a rectangular shape in a plan view and is a resin current collector (resin current collector) containing a conductive resin, which is a conductive polymer material. The conductive polymer material for 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, the same conductive additive as that contained in the coated positive electrode active material. The negative electrode current collector 20 may further contain a dispersant for the resin current collector. The negative electrode current collector 20 has a surface facing the positive electrode 1. 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 corresponds to 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.

[0014] Polyolefins are used as matrix resins constituting the conductive polymer material. From the viewpoint of electrical stability, polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), and polycycloolefin (PCO) are preferred, and polyethylene (PE), polypropylene (PP), and polymethylpentene (PMP) are more preferred.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] The frame 40 is annular in plan view and is provided between the uncovered portion (peripheral portion) of the surface of the positive electrode current collector 10 and the uncovered portion (peripheral portion) 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 has a third surface on at least one of the surface sides of the positive electrode current collector 10 and the negative electrode current collector 20. 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-rear and left-right directions in FIG. 1. In addition, in plan view, the four corners of the frame 40 are defined as corners, the outer peripheral edges of the corners are defined as corners, and the inner peripheral edges of the corners are defined as corners.

[0023] The secondary battery module 100 also includes a strong electric tab 50. The strong electric tab 50 may be, for example, a metal-plated nonwoven fabric sheet. The strong electric tab 50 is in surface contact with part of the electrode 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 electrode current collectors with which the strong electric tab 50 is in surface contact are also the electrode current collectors of the outermost layers.

[0024] Here, for example, if a secondary battery module 100 including a high-voltage tab 50 made of a metal foil or metal plate such as copper is bent at an angle or a nail is driven into it, the high-voltage tab 50 may buckle, resulting in an unexpected situation for the secondary battery module 100. A metal-plated nonwoven fabric sheet, as in this embodiment, is flexible and has a lower electrical resistance than metal foil or metal plate, making it less susceptible to buckling. Examples of metal-plated nonwoven fabric sheets include conductive cloth / conductive nonwoven fabric (manufactured by Seiren Co., Ltd.) and silver-plated fiber nonwoven fabric (manufactured by Unix Corporation).

[0025] The secondary battery module 100 also includes an exterior body 60. The exterior body 60 houses the battery cells 5 and prevents the penetration of liquids, such as water, present outside the exterior body 60. The exterior body 60 may be, for example, a resin film. A compound containing isocyanate is preferable as the raw material for the exterior body 60. Specifically, a polyurea-based resin (polyurea is a registered trademark) produced by a chemical reaction between isocyanate and an amine group is suitable for the exterior body 60. Polyurea-based resins have high abrasion resistance due to the excellent rigidity of urea bonds, flexibility due to their elongation, and excellent water resistance, corrosion resistance, chemical resistance, and acid resistance, making them suitable for a tough exterior body 60. Polyurea-based resins are also suitable for the exterior body 60 because they are thermally stable after resin formation. Furthermore, the raw materials for polyurea-based resins are liquid at room temperature, making them easy to apply to the outer surfaces of the battery cells 5.

[0026] The exterior body 60 can suitably house the battery cells 5 by covering and sealing the outer periphery of the battery cells 5. The exterior body 60 is formed by spraying a liquid mixture of raw materials onto the outer periphery of the battery cells 5, covering and sealing them. Alternatively, the exterior body 60 may be formed by immersing the battery cells 5 in a liquid mixture of raw materials, and then covering and sealing the outer periphery of the battery cells 5. Alternatively, a laminate film formed by processing raw materials into a sheet may be prepared. The battery cells 5 may be placed on the laminate film, and the top and side surfaces of the battery cells 5 may be further covered and sealed with the laminate film, thereby suitably housing the battery cells 5 in the exterior body 60. Furthermore, the high-voltage tab 50 is sealed so that a portion thereof is exposed from the exterior body 60 and drawn out to the outside of the exterior body 60.

[0027] The materials of the components constituting the secondary battery module 100 are not limited to the above materials, and various materials can be used.

[0028] <Gas-permeable resin current collector> This section describes the case where gas is generated inside the battery cell 5 due to the initial charge of the secondary battery module 100, aging, or the like. As described above, the battery cell 5 is composed of a positive electrode 1 containing lithium and a negative electrode 2 that occludes lithium. Charging (discharging) of the battery cell 5 occurs when lithium moves from the positive electrode 1 to the negative electrode 2 (or from the negative electrode 2 to the positive electrode 1) via the electrolyte. During the initial charge process, a coating called an SEI (Solid Electrolyte Interphase) coating is formed on the surface of the negative electrode 2 due to decomposition of the electrolyte, etc. Chemical reactions that occur when this SEI coating is formed generate gases such as hydrogen, hydrocarbons, and carbon oxides inside the battery cell 5. The amount of gas generated increases when a certain voltage is applied.

[0029] As described above, the positive electrode current collector 10 and the negative electrode current collector 20 are resin current collectors containing a conductive resin, which is a conductive polymer material. The resin used for the positive electrode current collector 10 and the negative electrode current collector 20 has numerous minute voids at the molecular level, which actually allows gas (air) to pass through. By using resin current collectors as the positive electrode current collector 10 and the negative electrode current collector 20, if gas is generated inside the battery cell 5, the gas is released to the outside of the battery cell 5 through the surfaces of the positive electrode current collector 10 and the negative electrode current collector 20. This prevents inhibition of the battery reaction caused by the gas generated inside the battery cell 5 and suppresses deterioration of battery performance due to gas generation. Furthermore, any conductive material that has minute voids large enough to allow gas to pass through may be applicable as an electrode current collector. Furthermore, since the resin current collectors are flexible, by using resin current collectors as the positive electrode current collector 10 and the negative electrode current collector 20, it is possible to tolerate some degree of deformation of the shape of the secondary battery module 100, such as bending the secondary battery module 100 or pressing the secondary battery module 100 from the outside.

[0030] <Slope of electrode current collector> The battery cell 5 has a portion from which gas generated inside can be easily released, as will be described in detail below.

[0031] As shown in FIG. 1, a secondary battery module 100 has a plurality of battery cells 5 (four layers in the illustrated example) stacked on top of one another. For example, the top surface of the positive electrode current collector 10 of the second-highest battery cell 5 in FIG. 1 is in contact with the bottom surface of the negative electrode current collector 20 of the first-highest battery cell 5. Similarly, the bottom surface of the negative electrode current collector 20 of the second-highest battery cell 5 is in contact with the top surface of the positive electrode current collector 10 of the third-highest battery cell 5. Furthermore, these contacting portions are compressed by atmospheric pressure. Of the surfaces of the electrode current collectors of each battery cell 5 (the surfaces of the positive electrode current collector 10 and the negative electrode current collector 20), the top and bottom surfaces that are not exposed due to the contact and compression may not be able to smoothly release gas.

[0032] As shown in Fig. 1, the peripheral edge of each battery cell 5 is exposed and free from contact or pressure. Specifically, the thickness of the peripheral edge of the battery cell 5 is adjusted to be tapered. The peripheral edge of the battery cell 5 is inclined so that the thickness of the battery cell 5 becomes thinner from the center of the battery cell 5 toward the periphery in a cross-sectional view.

[0033] In the example of FIG. 1 , the total thickness of the negative electrode current collector 20, the negative electrode composition layer 21, the separator 30, the positive electrode current collector 10, and the positive electrode composition layer 11 is greater than the total thickness of the positive electrode current collector 10, the frame 40, and the negative electrode current collector 20. Therefore, as shown in FIG. 1 , the electrode current collector has an inclined slope 5a formed based on the difference in these total thicknesses. The slope 5a is an inclined portion covering the end (peripheral edge) of the electrode composition layer in a direction intersecting the thickness direction of the electrode composition layer. In other words, the peripheral edge of the battery cell 5 has the inclined slope 5a. The slope may be flat, or may be curved convexly or concavely. Here, the peripheral portion of the negative electrode composition layer 21 is referred to as the first peripheral portion, the inclined slope 50a of the negative electrode current collector 20 covering the first peripheral portion is referred to as the first inclined portion, the peripheral portion of the positive electrode composition layer 11 is referred to as the second peripheral portion, and the inclined slope 50a of the positive electrode current collector 10 covering the second peripheral portion is referred to as the second inclined portion.

[0034] The sloped surfaces 5a are exposed without contact or pressure, allowing gas to pass through more smoothly than the upper and lower surface portions of the surface of the electrode current collector of the battery cell 5. Furthermore, although the sloped surfaces 5a are narrower than the upper and lower surface portions of the surface of the electrode current collector of the battery cell 5, they are provided on the entire periphery (four sides) of the battery cell 5. Therefore, the sloped surfaces 5a have a sufficiently large area as a gas release region, allowing gas to pass through smoothly. This prevents inhibition of the battery reaction caused by gas generated inside the battery cell 5 and suppresses deterioration of battery performance due to gas generation.

[0035] In the case where the positive electrode current collector 10 and the negative electrode current collector 20 of the secondary battery module 100 are resin current collectors and the exterior body 60 of the secondary battery module 100 is a film made of a polyurethane resin, as in the present embodiment, deformation of the shape can be tolerated to some extent when the secondary battery module 100 is bent or pressed from the outside of the secondary battery module 100. Therefore, a strong case can be realized.

[0036] <Gas exhaust section> FIG. 2 (FIGS. 2a to 2c) are perspective views schematically illustrating a gas exhaust unit 70 according to this embodiment and a secondary battery module 100 including the gas exhaust unit 70. FIG. 2a shows the gas exhaust unit 70 alone. The gas exhaust unit 70 includes a flat, thin-plate-shaped base portion having a hole at its center penetrating from the front to back surfaces, a cylindrical portion standing vertically (upward in the figure) from the edge of the hole on the surface of the base portion, and a grip portion standing vertically and horizontally from the tip of the cylindrical portion. The grip portion includes a valve 71 at its center in a plan view for opening and closing the hole at the tip of the cylindrical portion. The valve 71 has, for example, one fixed end and the other free end, and the hole can be opened and closed by pinching and rolling up the other end.

[0037] FIG. 2b shows a battery cell 5 equipped with a gas exhaust section 70. The battery cell 5 is in an upright position with its first side facing the ground (bottom in the figure). The battery cell 5 is equipped with a high-voltage tab 50 on its surface (front and back in the figure). The lead portion of the high-voltage tab 50 runs along the second side (top in the figure), which is the opposite side of the first side of the battery cell 5, with the tip of the lead portion standing in the same axial direction as the surface of the battery cell 5. The gas exhaust section 70 is provided near the lead portion of the high-voltage tab 50, with the back surface of its base in contact with the second side of the battery cell 5. The gas exhaust section 70 may be fixed to the battery cell 5 with a rubber band or the like.

[0038] FIG. 2c shows a secondary battery module 100 in which a battery cell 5 equipped with a gas exhaust section 70 is covered with an exterior body 60. The exterior body 60 does not cover the tip of the lead portion of the high-voltage tab 50 or the grip portion of the gas exhaust section 70. The valve 71 provided in the grip portion can be released to the outside of the exterior body 60 by picking up the free end and rolling it up to open the hole at the tip side of the cylindrical portion. This makes it possible to suppress a decrease in battery performance due to gas generation.

[0039] Although the gas release section 70 is provided on the second side surface of the battery cell 5, it may also be provided on the first side surface of the battery cell 5. Furthermore, the gas release section 70 may also be provided on a third side surface (left side surface in FIG. 2c) or a fourth side surface (right side surface in FIG. 2c) that intersects with the second and first side surfaces of the battery cell 5. Furthermore, a plurality of gas release sections 70 may be provided instead of a single one.

[0040] Furthermore, the gripping portion may be rotatable (axially rotatable) around its center in a plan view. The rotation angle may be in the range of 0 to 90 degrees, for example, and the valve 71 may be opened or closed depending on the rotation angle. A rotation angle of 0 degrees indicates that the valve 71 is fully closed, a rotation angle of 45 degrees indicates that the valve 71 is half-open, and a rotation angle of 90 degrees indicates that the valve 71 is fully open.

[0041] <Modification> A secondary battery cell according to a modified example of this embodiment will be described. FIG. 3 is a perspective view schematically showing the secondary battery cell according to this modified example. For ease of explanation, the figure shows a state in which a portion of the positive electrode current collector 10 is rolled up, and also shows an enlarged view of a corner of the frame body 40 (the area circled in the figure). Note that the components constituting the battery cell 5 according to this modified example are similar to the components constituting the battery cell 5 according to this embodiment, and therefore descriptions thereof will be omitted.

[0042] The grooves 41 are arranged at the corners of the frame 40 in a plan view and are serpentine. The grooves 41 are formed from corner to corner of the frame 40, with one end of the groove 41 arranged at a corner of the frame 40 and the other end of the groove 41 arranged at a corner of the frame 40. The grooves 41 are serpentine, like a series of alternating U-shapes rotated 90 degrees counterclockwise or clockwise. The grooves 41 are formed by press working or the like from the top surface (third surface) of the frame 40 in a predetermined depth direction and a predetermined width direction. The cross-sectional shape of the grooves 41 is, for example, approximately V-shaped. The grooves 41 have a surface (curved surface 42 in FIG. 4) that is curved in a substantially V-shape in a cross-sectional view.

[0043] 4 is a cross-sectional schematic diagram showing a flow path (space) according to this modified example. The frame 40 is arranged on the upper surface 20a (second surface) of the negative electrode current collector 20 in the drawing. When the groove 41 is arranged on the upper surface 20a side of the negative electrode current collector 20 in the drawing, a flow path 43 is formed, which is defined by the upper surface 20a of the negative electrode current collector 20 in the drawing and the curved surface 42 of the groove 41. As described above, the groove 41 is meandering, and therefore the flow path 43 is also meandering. Note that, although not shown or described because it is the same as the above, there is a flow path defined by the surface (first surface) of the positive electrode current collector 10 and the curved surface 42 of the groove 41.

[0044] The flow paths 43 can release gas generated inside the battery cells 5. The flow paths 43 are gas release grooves that function as a gas release mechanism. The flow paths 43 are formed in a serpentine shape, which makes it difficult for the electrolyte solution and the like to leak from the positive electrode composition layer 11 and the negative electrode composition layer 21.

[0045] The frame body 40 may be configured, for example, by combining two frame body members (hereinafter also simply referred to as frame body members) that are L-shaped or U-shaped in a plan view. The two frame body members that make up the frame body 40 have the same shape and structure and have concave and convex shapes at both ends. In the frame body 40, the concave and convex shapes of one frame body member and the concave and convex shapes of the other frame body member are fitted together. By fitting the concave and convex shapes of the frame body members together in this way, the above-mentioned serpentine groove 41 is formed.

[0046] Although the grooves 41 are configured to be serpentine to prevent leakage of electrolyte and the like, they may be further configured to prevent leakage. For example, the grooves 41 may have a liquid-repellent (water-repellent) coating layer on their surface. By applying a coating agent to the surface of the grooves 41 to make them liquid-repellent, the coating layer (film) formed on the surface of the grooves 41 exhibits liquid-repellent properties. This repels electrolyte and the like, further preventing leakage and allowing only gas to be released. Examples of coating agents include fluorine-based agents such as "Fluorosurf (registered trademark)" manufactured by Fluorotechnology Co., Ltd. and "Surflon (registered trademark)" manufactured by AGC Seimi Chemical Co., Ltd. Other examples of coating agents include "JC Coat (registered trademark)" manufactured by Taiyo Yuden Chemical Technology Co., Ltd. Note that configurations other than the liquid-repellent coating layer may also be used.

[0047] The frame 40 may be composed of multiple frame members of different shapes. For example, it may be composed of a ring-shaped frame member (large frame member) with a portion cut out, combined with a frame member (small frame member) that corresponds to the cut-out portion. The large frame member may be made of a thermosetting polymer material, similar to the frame members described above. On the other hand, the small frame member may be a porous (mesh-like) film made of polymer or fiber. When the frame 40 is composed of a large frame member and small frame members combined together, the small frame member serves to release gas generated inside the battery cell 5. The small frame member may also have a liquid-repellent (water-repellent) coating layer that repels liquids.

[0048] As described above, the secondary battery according to the present embodiment has been described. However, it goes without saying that those skilled in the art can appropriately add, modify, or omit parts of the present embodiment within the scope of the technical concept thereof.

[0049] The secondary battery has been described as a lithium-ion secondary 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 5 of an all-solid-state lithium-ion battery uses a solid electrolyte instead of the liquid electrolyte. This battery cell 5 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 in which a positive electrode active material is interposed within this solid electrolyte. The negative electrode composition layer 21 is in a state in which a negative electrode active material is interposed within this solid electrolyte. The details and materials of each component constituting this battery cell 5 are the same as those of each component constituting the battery cell 5 according to this embodiment. [Industrial Applicability]

[0050] By using the secondary battery according to this embodiment in, for example, an electric vehicle or a hybrid vehicle, a long driving distance per charge and a long life can be achieved. [Explanation of symbols]

[0051] 1 positive electrode 2 negative electrode 5 battery cells 5a Slope 10 Positive electrode current collector 11 Positive electrode composition layer 20 Negative electrode current collector 20a Upper surface of negative electrode current collector 21 Negative electrode composition layer 30 Separator 40 Frame 41 Groove 42 Curved Surface 43 Flow path 50 High Voltage Tab 60 Exterior body 70 Gas exhaust section 71 Valve 100 Secondary battery (lithium ion battery)

Claims

1. A secondary battery module including a 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, and an exterior body that houses the battery cell, The battery cell has a structure that can release gas generated inside, The outer casing is a polymer resin compound produced by a chemical reaction between an isocyanate and an amine group. Secondary battery module.

2. the negative electrode current collector includes a first inclined portion that covers a first peripheral edge portion of the negative electrode composition layer and is inclined; the positive electrode current collector includes a second inclined portion that covers a second peripheral edge portion of the positive electrode composition layer and is inclined; the negative electrode current collector and the positive electrode current collector allow gas generated inside the battery cell to permeate through the first inclined portion and the second inclined portion, The secondary battery module according to claim 1 .

3. the battery cell further includes a frame covering at least a portion of a side surface of the positive electrode composition layer and a side surface of the negative electrode composition layer, the frame has a liquid-repellent flow path and / or a meandering flow path extending from its inner peripheral edge to its outer peripheral edge; The secondary battery module according to claim 1 .

4. a high-current tab in surface contact with the negative electrode current collector and the positive electrode current collector in the outermost layer of the battery cell; The high-voltage tab is a metal-plated nonwoven fabric sheet. The secondary battery module according to claim 1 .

5. a gas exhaust portion on a side surface of the battery cell; the gas exhaust unit includes a valve that exhausts gas generated inside the battery cell to the outside of the exterior body. The secondary battery module according to claim 1 .

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