Laminated lithium-ion secondary battery and power storage device

Abstract

To provide a laminated lithium ion secondary battery capable of attaining downsizing or space savings of a power storage device including a battery module or a battery pack and capable of solving complication of a manufacturing process, and the power storage device.SOLUTION: A laminated lithium ion secondary battery comprises a cathode, an anode, a separator, a non-aqueous electrolyte, a cathode terminal, an anode terminal, and a sheath material. The cathode terminal includes a cathode contact part, a first exposure part, and a first sealant part fused with a thermal fusion layer of the sheath material. The anode terminal includes an anode contact part, a second exposure part, and a second sealant part fused with the thermal fusion layer of the sheath material. The sheath material includes a first opening exposing the first exposure part outside and a second opening exposing the second exposure part outside. The first sealant part encloses at least a portion of an outer periphery of the first exposure part, and the second sealant part encloses at least a portion of an outer periphery of the second exposure part. The cathode terminal and the anode terminal do not include tab parts protruding from the sheath material.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a laminated lithium ion secondary battery and an electricity storage device. [Background technology]

[0002] Secondary batteries as energy storage devices are widely used not only to replace primary batteries but also as power sources for electronic devices such as mobile phones and IT equipment. In particular, secondary batteries such as lithium-ion secondary batteries are being applied to large consumer and industrial electrical devices such as electric vehicles and power supply units, and in these cases, they are generally used with the aim of achieving high output and large capacity. In particular, with the trend toward smaller size, lighter weight, and various changes in shape, laminated exterior materials, in which resin films are bonded to both sides of metal foil with adhesive, are increasingly being used instead of the metal exteriors that were previously used. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6632831 [Patent Document 2] Patent No. 6661459 [Patent Document 3] Patent No. 6666096 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional laminated lithium-ion secondary batteries using laminated exterior materials have a basic structure in which a tab metal terminal protrudes from at least one end of the battery. Therefore, when laminated lithium-ion secondary batteries are joined together with a bus bar or the like, this creates an unnecessary, unusable space in the output terminal structure of a battery module or battery pack made up of multiple batteries, reducing the structural flexibility of the device equipped with the batteries.

[0005] Furthermore, the tab metal terminals protruding from the laminated lithium-ion secondary battery require additional processing such as cutting or bending due to the design of adjusting the length of the tab metal terminals and joining the tab metal terminals together, which may increase the number of processing steps and make the processing process even more complicated.

[0006] Incidentally, Patent Documents 1 to 3 aim to reduce size and weight by exposing the metal foil layer of the exterior material and forming electrode terminals (tab metal terminals), but this technology is applied to small and relatively thin capacitors and is thought to be difficult to apply to laminated lithium-ion batteries that require a capacity of several Ah and draw current from electrodes that are large in area, thick, and multi-layered.

[0007] In view of the above, an object of the present invention is to provide a laminated lithium ion secondary battery and a power storage device that can reduce the size and space of a power storage device including a battery module or battery pack and increase the battery capacity, something that could not be achieved with conventional laminated lithium ion secondary batteries. [Means for solving the problem]

[0008] In order to solve the above problems, the laminated lithium-ion secondary battery of the present invention is a laminated lithium-ion secondary battery comprising: a positive electrode having a positive electrode current collector and a positive electrode composite layer; a negative electrode having a negative electrode current collector and a negative electrode composite layer; a separator insulating the positive electrode and the negative electrode; a non-aqueous electrolyte; a positive electrode terminal in contact with the positive electrode current collector; a negative electrode terminal in contact with the negative electrode current collector; and an exterior material made of a laminated film having a heat-sealing layer and a metal foil layer, the exterior material incorporating the positive electrode, the negative electrode, the separator, the non-aqueous electrolyte, the positive electrode terminal, and the negative electrode terminal, wherein the positive electrode terminal has a positive electrode contact portion in contact with the positive electrode current collector, a first exposed portion exposed to the outside of the laminated lithium-ion secondary battery, and a second exposed portion exposed to the outside of the laminated lithium-ion secondary battery. the negative electrode terminal has a negative electrode contact portion in contact with the negative electrode current collector, a second exposed portion exposed to the outside of the laminated lithium-ion secondary battery, and a second sealant portion fused to the heat-sealing layer of the exterior material, the exterior material has a first opening exposing the first exposed portion to the outside and a second opening exposing the second exposed portion to the outside, the first sealant portion surrounds at least a part of the outer periphery of the first exposed portion and the second sealant portion surrounds at least a part of the outer periphery of the second exposed portion, and the positive electrode terminal and the negative electrode terminal do not have tab portions protruding from the exterior material. [Effects of the Invention]

[0009] The present invention can provide a laminated lithium ion secondary battery and a power storage device that can reduce the size and space of a power storage device including a battery module or battery pack, and eliminate the need for an increased battery capacity and complicated manufacturing process, which were not possible with conventional laminated lithium ion secondary batteries. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a perspective schematic view of a laminated lithium ion secondary battery 100 according to one embodiment of the present invention. [Figure 2]2A and 2B are schematic cross-sectional views of a laminated lithium ion secondary battery 100, where FIG. 2A is a cross-sectional view taken along line AA in FIG. 1, and FIG. 2B is a cross-sectional view taken along line BB in FIG. [Figure 3] 3(a) and 3(d) are schematic front views of a positive electrode terminal 50, a negative electrode terminal 60, an electrode assembly 80, and a laminated type lithium ion secondary battery 100, where FIG. 3(a) shows the positive electrode terminal 50, FIG. 3(b) shows the negative electrode terminal 60, FIG. 3(c) shows the electrode assembly 80, and FIG. 3(d) shows the laminated type lithium ion secondary battery 100. [Figure 4] 4(a) and 4(d) are schematic front views of a positive electrode terminal 50a, a negative electrode terminal 60a, an electrode assembly 80a, and a laminated lithium-ion secondary battery 100a in an embodiment different from that shown in FIG. 3, where FIG. 4(a) shows the positive electrode terminal 50a, FIG. 4(b) shows the negative electrode terminal 60a, FIG. 4(c) shows the electrode assembly 80a, and FIG. 4(d) shows the laminated lithium-ion secondary battery 100a. [Figure 5] 5(a) and 5(d) are schematic front views of a positive electrode terminal 50b, a negative electrode terminal 60b, an electrode assembly 80b, and a laminate-type lithium-ion secondary battery 100b in an embodiment different from those shown in FIGS. 3 and 4, where FIG. 5(a) shows the positive electrode terminal 50b, FIG. 5(b) shows the negative electrode terminal 60b, FIG. 5(c) shows the electrode assembly 80b, and FIG. 5(d) shows the laminate-type lithium-ion secondary battery 100b. [Figure 6] FIG. 6 is a schematic front view of a laminated lithium-ion secondary battery 100c in an embodiment different from those in FIGS. [Figure 7] 7(a) and 7(d) are schematic front views of a positive electrode terminal 50d, a negative electrode terminal 60d, an electrode assembly 80d, and a laminated lithium-ion secondary battery 100d in an embodiment different from those shown in FIGS. 3 to 6, where FIG. 7(a) shows the positive electrode terminal 50d, FIG. 7(b) shows the negative electrode terminal 60d, FIG. 7(c) shows the electrode assembly 80d, and FIG. 7(d) shows the laminated lithium-ion secondary battery 100d. [Figure 8] FIG. 1 is a schematic front view of a conventional laminated lithium ion secondary battery 200. [Figure 9]8(a) and 8(c) are diagrams comparing the sizes of a battery module 350 equipped with a conventional laminated lithium-ion secondary battery 200 and battery modules 300 and 310 equipped with a laminated lithium-ion secondary battery 100 of the present invention, where FIG. 8(a) is battery module 350, FIG. 8(b) is battery module 300, and FIG. 8(c) is battery module 310. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the laminated lithium ion secondary battery and the power storage device of the present invention will be described with reference to the drawings, although the present invention is not limited to the following embodiment.

[0012] [Laminated lithium-ion secondary battery] First Embodiment Fig. 1 is a schematic perspective view of a laminated lithium-ion secondary battery 100 according to one embodiment of the present invention. Fig. 2 is a schematic cross-sectional view of the laminated lithium-ion secondary battery 100, with Fig. 2(a) being a cross-sectional view taken along line AA in Fig. 1 and Fig. 2(b) being a cross-sectional view taken along line BB in Fig. 1. Fig. 3 is a schematic front view of a positive electrode terminal 50, a negative electrode terminal 60, an electrode assembly 80, and the laminated lithium-ion secondary battery 100, with Fig. 3(a) showing the positive electrode terminal 50, Fig. 3(b) showing the negative electrode terminal 60, Fig. 3(c) showing the electrode assembly 80, and Fig. 3(d) showing the laminated lithium-ion secondary battery 100.

[0013] The laminated lithium ion secondary battery 100 includes a positive electrode 10, a negative electrode 20, a separator 30, a non-aqueous electrolyte 40, a positive electrode terminal 50, a negative electrode terminal 60, and an exterior material .

[0014] (positive electrode 10) Positive electrode 10 has a positive electrode current collector 11 and a positive electrode mixture layer 12. Positive electrode mixture layer 12 contains, for example, a positive electrode active material, a conductive material, and a binder.

[0015] The positive electrode active material is not particularly limited as long as it is a compound generally used as a positive electrode active material for a lithium secondary battery such as a lithium-containing metal oxide. For example, lithium cobalt composite oxide (e.g., LiCoO2), lithium manganese composite oxide (e.g., LiMnO2, LiMn2O4, LiMn2O3), lithium nickel composite oxide (e.g., LiNiO2), lithium cobalt iron composite oxide (e.g., LiCo 0.5 Fe 0.5 O2), lithium nickel cobalt manganese composite oxide (e.g., Li(Ni x Co y Mn 1-x-y )O2 (0 < x < 1, 0 < y < 1)), lithium iron phosphate composite oxide (e.g., LiFePO4), etc. can be mentioned.

[0016] The positive electrode current collector 11 is, for example, aluminum or an aluminum alloy. Examples of the material of the positive electrode current collector include aluminum foil, metal meshes such as aluminum, metal porous bodies, expanded metal, punched metal, etc.

[0017] The conductive material is not particularly limited, and known or commercially available materials can be used. For example, carbon blacks such as acetylene black and ketjen black, carbon nanotubes, carbon fibers, activated carbon, graphite, etc. can be mentioned.

[0018] The binder is not particularly limited, and known or commercially available materials can be used. For example, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinylpyrrolidone (PVP), polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), ethylene-propylene copolymer, styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), acrylic resin, etc. can be mentioned.

[0019] (Negative electrode 20) The negative electrode 20 has a negative electrode current collector 21 and a negative electrode composite material layer 22, and includes, for example, the negative electrode current collector 21 and a negative electrode composite material layer 22 containing a negative electrode active material formed on one or both surfaces of the negative electrode current collector 21.

[0020] The negative electrode active material is not particularly limited as long as it is a material that allows dissolution or deposition of metal or insertion and desorption of metal ions. Examples of the negative electrode active material include lithium metal, carbon-based materials, silicon, silicon alloys, and tin. Examples of carbon-based materials that allow insertion and desorption of lithium ions include powdered or fibrous graphite.

[0021] There are no particular limitations on the negative electrode current collector 21, and any known or commercially available one can be used. Examples of the negative electrode current collector include rolled foil and electrolytic foil made of copper or a copper alloy.

[0022] (Separator 30) The separator 30 insulates the positive electrode 10 and the negative electrode 20, and can be, for example, a stretched film, a microporous membrane, or a nonwoven fabric of a polyolefin resin such as a polyethylene resin or a polypropylene resin, a polytetrafluoroethylene resin, a cellulose, or a polyimide. The stretched film, the microporous membrane, or the nonwoven fabric may have a single layer or a multilayer structure. The separator may particularly preferably be a microporous polyethylene membrane. Examples of the separator 30 include a separator that is cut and placed between each of the positive electrode 10 and the negative electrode 20 to provide insulation, and a separator that is folded in a zigzag shape to insulate multiple positive electrodes 10 and multiple negative electrodes 20.

[0023] (Non-aqueous electrolyte 40) When the non-aqueous electrolyte 40 is in a liquid state, it contains a non-aqueous solvent and an electrolyte.

[0024] The non-aqueous solvent preferably contains a cyclic carbonate and a chain carbonate as main components. The cyclic carbonate is preferably at least one selected from ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylene carbonate (VC), and γ-butyrolactone (GBL). The chain carbonate is preferably at least one selected from dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), etc.

[0025] The electrolyte is not particularly limited, and any lithium salt electrolyte commonly used in lithium secondary batteries can be used. For example, LiPF, LiBF, LiAsF, LiClO, LiCFSO, LiN(CFSO)(CFSO), LiN(C m F 2m+1 SO2)(C n F 2n+1 SO2) (m and n are integers of 1 or more), LiC(C p F 2p+1 SO2)(C q F 2q+1 SO2)(C r F 2r+1 SO2) (p, q, and r are integers of 1 or more), lithium difluoro(oxalato)borate, etc. can be used. These electrolytes can be used alone or in combination of two or more. The electrolyte is desirably dissolved in the non-aqueous solvent at a concentration of 0.1 to 1.5 mol / L, preferably 0.5 to 1.5 mol / L.

[0026] (Positive terminal 50) The positive electrode terminal 50 is a terminal that contacts the positive electrode current collector 11. As shown in Fig. 3(a), the positive electrode terminal 50 has a positive electrode contact portion 51 that contacts the positive electrode current collector 11, a first exposed portion 52 that is exposed to the outside of the laminated lithium-ion secondary battery 100, and a first sealant portion 53 that is fused to the heat-sealing layer of the exterior material 70. The first sealant portion 53 surrounds the outer periphery of the first exposed portion 52.

[0027] (Negative terminal 60) The negative electrode terminal 60 is a terminal that contacts the negative electrode current collector 21. As shown in Fig. 3(b), the negative electrode terminal 60 has a negative electrode contact portion 61 that contacts the negative electrode current collector 21, a second exposed portion 62 that is exposed to the outside of the laminated lithium-ion secondary battery 100, and a second sealant portion 63 that is fused to the heat-sealing layer of the exterior material 70. The second sealant portion 63 surrounds the outer periphery of the second exposed portion 62.

[0028] (Welding method and welding width for laminated lithium-ion secondary batteries) From the viewpoint of increasing the battery capacity, when connecting and using a plurality of laminated lithium-ion secondary batteries 100, it is desirable to weld the plurality of laminated lithium-ion secondary batteries 100 with a bus bar. Examples of welding methods include ultrasonic welding, resistance welding, and fiber laser welding. When the area of ​​the first exposed portion 52 and the second exposed portion 62 is 2000 μm 2 If each side is 50 μm or longer, the tab terminal and bus bar can be welded by fiber laser welding. However, if other welding methods are used, or from the standpoints of weld strength, heat suppression, input / output performance, etc., it is preferable to ensure a larger area and a longer side. On the other hand, to reduce the size of the battery, it is preferable that the exposed length of the first exposed portion 52 and the second exposed portion 62 in the short direction of the first sealant portion 53 and the second sealant portion 63 be 10 mm or less.

[0029] The area and shape of the first exposed portion 52 and the second exposed portion 62 may be the same or different. Furthermore, the area, shape, and position of each exposed portion may be different on the front and back surfaces in the planar direction of the laminated lithium-ion secondary battery 100. The first exposed portion 52 and the second exposed portion 62 may both be present on both the front and back surfaces in the planar direction of the laminated lithium-ion secondary battery 100, or may both be present on only one surface. The first exposed portion 52 and the second exposed portion 62 may or may not be present on the front and back surfaces in the planar direction of the laminated lithium-ion secondary battery 100.

[0030] Furthermore, the first sealant portion 53 surrounding the first exposed portion 52 and the second sealant portion 63 surrounding the second exposed portion 62 preferably have a minimum width of 1 mm or more, and more preferably a width of 5 mm, from the viewpoint of the stability of the fusion operation with the exterior material 70. From the viewpoint of miniaturization of the laminated lithium-ion secondary battery 100, the first sealant portion 53 surrounding the first exposed portion 52 and the second sealant portion 63 surrounding the second exposed portion 62 preferably have a minimum width of 10 mm or less.

[0031] Furthermore, from the viewpoint of seal durability and water vapor barrier property, the fused portion between the exterior material 70 surrounding the first exposed portion 52 and the fused portion between the exterior material 70 surrounding the second exposed portion 62 preferably have a smallest width of 1 mm or more, and more preferably a width of 5 mm. From the viewpoint of battery miniaturization, the fused portion between the exterior material 70 surrounding the first exposed portion 52 and the fused portion between the exterior material 70 surrounding the second exposed portion 62 preferably have a smallest width of 10 mm or less.

[0032] Additionally, with regard to the width in the same direction of the fused portion between first sealant portion 53 surrounding first exposed portion 52 and exterior material 70 surrounding first exposed portion 52, from the viewpoint of preventing short circuits, the width of first sealant portion 53 is preferably about 2 to 3 mm longer than the width of the fused portion in any direction, but the widths may be the same. The same applies to the width of the fused portion between second sealant portion 63 surrounding second exposed portion 62 and exterior material 70 surrounding second exposed portion 62.

[0033] As will be described in detail later, unlike conventional batteries, in laminated lithium-ion secondary battery 100, the positive electrode terminal 50 and the negative electrode terminal 60 do not have tab portions that protrude from the exterior material 70, which makes it possible to reduce the size of the battery and increase the battery capacity. Furthermore, the absence of tab portions eliminates the need for additional processing such as cutting or bending the tab portions, which does not increase or complicate the processing steps.

[0034] (Exterior material 70) The exterior material 70 is made of a laminate film having a heat-sealing layer and a metal foil layer, and contains the positive electrode 10, the negative electrode 20, the separator 30, the non-aqueous electrolyte 40, the positive electrode terminal 50, and the negative electrode terminal 60 inside.

[0035] The exterior material 70 is, for example, bag-shaped and houses a flat electrode assembly 80 (FIG. 3(c)), which will be described later. The laminate film has a structure in which, for example, multiple (for example, two) plastic films are laminated together with a metal foil, such as aluminum foil, sandwiched between them as a metal foil layer. One of the two plastic films uses a heat-sealable resin film as a heat-sealable layer. The exterior material 70 has two laminate films stacked together with the heat-sealable resin films facing each other, with the electrode assembly 80 interposed between these laminate films, and the two laminate film portions (heat-sealed portions 73 in FIG. 3(d)) around the electrode assembly 80 sealed on all four sides to hermetically house the electrode assembly 80.

[0036] The exterior material 70 has a first opening 71 that exposes the first exposed portion 52 of the positive terminal 50 to the outside and a second opening 72 that exposes the second exposed portion 62 of the negative terminal 60 to the outside. By providing the first opening 71 and the second opening 72, the first exposed portion 52, which is part of the positive terminal 50, and the second exposed portion 62, which is part of the negative terminal 60, can be exposed to the outside without a tab portion. Instead of a tab portion, the first exposed portion 52 and the second exposed portion 62 can be connected by a bus bar or the like. In this case, the first exposed portion 52 and the second exposed portion 62 are preferably provided in a heat-sealed portion 73 formed by sealing the laminate film by heat fusion. In other words, the first exposed portion 52 and the second exposed portion 62 are preferably exposed from the heat-sealed portion 73, so that the positive terminal 50 and the negative terminal 60 are exposed from the heat-sealed portion 73. The reason for this is that there is no need to provide a new fusion portion on the terrace portion, and the fusion position is less likely to shift than in a thick terrace portion.

[0037] (electrode assembly 80) As shown in FIG. 2( a), the electrode assembly 80 has a structure in which a positive electrode 10, a negative electrode 20, and a separator 30 interposed between the positive electrode 10 and the negative electrode 20 are stacked in multiple layers, with the negative electrode 20 positioned as the outermost layer. The positive electrode 10 is composed of a positive electrode current collector 11 and a positive electrode composite layer 12 formed on both sides of the current collector 11. The negative electrode 20 is composed of a negative electrode current collector 21 and a negative electrode composite layer 22 formed on both sides of the current collector 21. Note that the negative electrode 20 positioned as the outermost layer does not necessarily need to include the negative electrode composite layer 22 on the surface of the negative electrode current collector 21 facing the exterior material.

[0038] The positive electrode 10 has a positive electrode current collector 11 extending from the positive electrode composite layer 12 to the positive electrode terminal 50, and each positive electrode current collector 11 is bundled at the tip side within the exterior packaging material 70 and welded to the positive electrode contact portion 51 of the positive electrode terminal 50 by a first welding portion 54 (see Figure 3(c)) so as to be joined to each other.

[0039] The negative electrode 20 has a negative electrode current collector 21 extending from the negative electrode composite layer 22 to the negative electrode terminal 60, and each negative electrode current collector 21 is bundled at the tip side within the exterior packaging material 70 and welded to the negative electrode contact portion 61 of the negative electrode terminal 60 by a second welding portion 64 (see Figure 3(c)) so as to be joined to each other.

[0040] Furthermore, the first sealant portion 53 of the positive electrode terminal 50 is heat-sealed to the heat-sealing portion 73 of the exterior material 70 , preventing the non-aqueous electrolyte 40 inside the exterior material 70 from leaking from the first opening 71 .

[0041] Similarly, in the negative electrode terminal 60 , the second sealant portion 63 is heat-sealed to the heat-sealed portion 73 of the exterior material 70 , preventing the non-aqueous electrolyte 40 inside the exterior material 70 from leaking from the second opening 72 .

[0042] When the battery capacity of the laminated lithium-ion secondary battery 100 is 1 Ah or more, the thickness of the positive electrode contact portion 51 of the positive electrode terminal 50 and the negative electrode contact portion 61 of the negative electrode terminal 60 may be, for example, 0.3 mm or more depending on the capacity and size, making it difficult to fold them accurately. Therefore, when attempting to fold the positive electrode terminal 50 and the negative electrode terminal 60 and store them in the exterior material 70, extra gaps may be created inside the exterior material 70, or it may be difficult to position the positive electrode terminal 50 and the negative electrode terminal 60. Therefore, particularly when the battery capacity is 1 Ah or more, it is preferable that the positive electrode terminal 50 and the negative electrode terminal 60 are built into the exterior material 70 without being bent. Furthermore, even when the battery capacity is less than 1 Ah, there is no problem with building them in without being bent if bending is not necessary.

[0043] (Terrace area 90) The laminated lithium-ion secondary battery 100 may include a terrace portion 90 that includes a positive electrode terminal contact portion 13 that contacts the positive electrode contact portion 51 of the positive electrode current collector 11, a negative electrode terminal contact portion 23 that contacts the negative electrode contact portion 61 of the negative electrode current collector 21, the positive electrode contact portion 51 of the positive electrode terminal 50, and the negative electrode contact portion 61 of the negative electrode terminal 60, such that a first exposed portion 52 and a second exposed portion 62 are exposed from a first opening 71 and a second opening 72 provided at the same end of the exterior packaging material 70. Note that in this specification, the term "terrace portion" refers to a portion of the housing portion of the lithium-ion secondary battery where the non-embossed portions of the laminate exterior packaging material face each other and where the non-formed portion of the positive electrode mixture layer 12 of the positive electrode 10 and the non-formed portion of the negative electrode mixture layer 22 of the negative electrode 20 of the electrode assembly including the positive electrode 10, the negative electrode 20, and the separator 30 are housed.

[0044] However, the laminated lithium-ion secondary battery of the present invention also includes a battery that does not have terrace portion 90. For example, when first opening 71 and second opening 72 are provided at different ends of exterior packaging material 70, terrace portion 90 may not be provided.

[0045] Second Embodiment Figure 4 is a schematic front view of a positive electrode terminal 50a, a negative electrode terminal 60a, an electrode assembly 80a, and a laminate-type lithium-ion secondary battery 100a in an embodiment different from those shown in Figure 3. Three rectangular first exposed portions 52a and three rectangular second exposed portions 62a are provided, and three rectangular first openings 71a and three rectangular second openings 72a are provided corresponding to these. Note that the number of first exposed portions 52a and three rectangular second exposed portions 62a is not limited to three, and may be different numbers.

[0046] Third Embodiment 5 is a schematic front view of a positive electrode terminal 50b, a negative electrode terminal 60b, an electrode assembly 80b, and a laminate-type lithium-ion secondary battery 100b in an embodiment different from those shown in FIGS. 3 and 4. Three circular first exposed portions 52b and three circular second exposed portions 62b are provided, and three corresponding circular first openings 71b and three corresponding circular second openings 72b are provided. Note that the number of first exposed portions 52b and three corresponding second exposed portions 62b is not limited to three and may be different numbers.

[0047] Fourth Embodiment FIG. 6 is a schematic front view of a laminated lithium-ion secondary battery 100c in a different embodiment from those shown in FIGS. 3 to 5. In the first to third embodiments, the four sides of two laminate films are heat-sealed to form the exterior packaging material 70. In the fourth embodiment, however, a single laminate film is folded at a folding portion 74, and the three areas of the opening indicated by the dotted lines are heat-sealed to form the exterior packaging material 70a as a heat-sealed portion 73a. The folding portion 74 is preferably positioned to bisect the laminate film. This is because if the folding portion 74 is positioned to bisect the laminate film, there will be no non-overlapping portion of the laminate film (hereinafter referred to as excess). Even if the folding portion is not positioned to bisect the laminate film, it is preferable to adjust it so that the excess portion is eventually cut off and the laminate film is divided into two equal parts. Furthermore, first opening 71c and second opening 72c are provided on the side where bent portion 74 is located, and the inside of exterior material 70a is heat-sealed to first sealant portion 53 and second sealant portion 63 to prevent nonaqueous electrolyte 40 contained in exterior material 70 from leaking to the outside. In this embodiment, one side of the heat-sealed portion of the exterior material can be omitted, making it possible to provide a battery that takes up less space.

[0048] Fifth Embodiment 7 is a schematic front view of a positive electrode terminal 50d, a negative electrode terminal 60d, an electrode assembly 80d, and a laminated lithium-ion secondary battery 100d in a configuration different from that shown in FIGS. 3 to 6. In the first to fourth embodiments, the first exposed portions 52, 52a, and 52b and the second exposed portions 62, 62a, and 62b are heat-sealed on all four sides, respectively. In the fifth embodiment, a single laminate film is folded at a folding portion 74d, and the three areas of the openings indicated by the dotted lines are heat-sealed to form a thermally sealed portion 73d as in the fourth embodiment, forming an exterior material 70a. One end 71e or 72e of at least one of the first opening 71d and the second opening 72d is located along or inside the side of the laminated lithium-ion secondary battery 100d that is closest to the first opening 71d and the second opening 72d (e.g., the folding portion 74d).

[0049] In this embodiment, one end 71e or 72e of at least one of the first opening 71d and the second opening 72d is not fixed by the exterior material 70d, which facilitates processing of the laminated lithium-ion secondary battery 100d after completion, and since the positive electrode terminal 50d and the negative electrode terminal 60d do not protrude, it is possible to provide a battery that occupies less space than the conventional laminated lithium-ion secondary battery 200. Furthermore, if the laminated lithium-ion secondary battery 100d has the bent portion 74d as in the fourth embodiment, even greater space savings can be expected.

[0050] <Conventional form> 8 is a schematic front view of a conventional laminated lithium-ion secondary battery 200. An exterior packaging material 270 has no openings, and four sides are heat-sealed to form heat-sealed portions 273. A positive electrode tab terminal 210 and a negative electrode tab terminal 220 protrude from the exterior packaging material 270.

[0051] The electrode assembly built into the exterior material 270 may be the same as the electrode assembly 80 of the laminated lithium-ion secondary battery 100, and a positive electrode tab terminal 210 and a negative electrode tab terminal 220 are provided instead of the positive electrode terminal 50 and the negative electrode terminal 60.

[0052] <Comparison with conventional form> Next, the effects obtained by the laminated lithium ion secondary battery 100 of the present invention will be described by comparing it with a conventional laminated lithium ion secondary battery 200 with reference to FIG.

[0053] FIG. 9 is a diagram comparing the sizes of a battery module 350 including a conventional laminated lithium-ion secondary battery 200 and battery modules 300 and 310 including the laminated lithium-ion secondary battery 100 of the present invention.

[0054] Battery module 350 in Fig. 9(a) is a schematic side view showing three laminated lithium-ion secondary batteries 200 arranged in parallel inside a housing 400. In comparison, battery module 300 in Fig. 9(b) is a schematic side view showing three laminated lithium-ion secondary batteries 100 arranged in parallel inside a housing 410. Although battery module 300 and battery module 350 have different terminals, they have the same built-in electrode assembly 80, and therefore have the same performance as battery modules. However, battery module 300 is a smaller module because it does not have tab terminals.

[0055] That is, when the battery module has the same performance, the use of the laminated lithium ion secondary battery 100 makes it possible to reduce the size of the ionization module compared to the use of the conventional laminated lithium ion secondary battery 200. This effect is not limited to the first embodiment, but can also be obtained in the batteries of the second to fourth embodiments.

[0056] Next, a battery module 310 in FIG. 8(c) will be described for comparison with FIG. 9(a). The battery module 310 is a schematic side view showing three laminated lithium-ion secondary batteries 100 arranged in parallel in the same housing 400 as in FIG. 9(a). In the case of the battery module 310, an electrode assembly 80 larger than that of the battery module 350 is built into the exterior material 70. Therefore, although the two battery modules have the same size, the battery module 310 has a larger battery capacity than the battery module 350. For example, if the battery capacity of the laminated lithium-ion secondary battery 200 in FIG. 9(a) is 14 Ah, the battery capacity of the laminated lithium-ion secondary battery 100 in FIG. 9(c) can be increased by approximately 1.2 times, that is, to 17 Ah.

[0057] That is, for a battery module of the same size, using the laminated lithium ion secondary battery 100 makes it possible to achieve higher performance in the battery module than using the conventional laminated lithium ion secondary battery 200. This effect is not limited to the first embodiment, but is also obtained in the batteries of the second to fourth embodiments.

[0058] [Example of a manufacturing method for a laminated lithium-ion secondary battery] Next, an example of a method for manufacturing a battery with a battery capacity of 14.0 Ah will be described, taking the laminated lithium ion secondary battery 100 of the present invention as an example.

[0059] <Positive electrode 10> A positive electrode mixture slurry was prepared by dispersing 90 parts by weight of LiFePO4 (lithium iron phosphate), 5 parts by weight of PVDF (polyvinylidene fluoride), and 5 parts by weight of carbon black (a conductive additive) in N-methyl-2-pyrrolidone (NMP) as a solvent. This positive electrode mixture slurry was applied to both sides of a 20 μm aluminum foil (positive electrode current collector 11), dried, and then rolled to obtain a positive electrode 10. A predetermined shape and size were obtained by punching out the positive electrode mixture layer 12 into a portion where it was to be formed and a portion where it was not to be formed using a die.

[0060] <Negative electrode 20> A negative electrode mixture slurry was prepared by dispersing 98 parts by mass of graphite, 1 part by mass of CMC (carboxyl methyl cellulose), and 1 part by weight of SBR (styrene butadiene rubber) in ion-exchanged water as a solvent. The slurry was applied to both sides of a 10 μm copper foil (negative electrode current collector 21), dried, and then rolled to obtain a negative electrode 20. A negative electrode was obtained by punching out the negative electrode mixture layer 22 into a predetermined shape and size using a die, so that the area where the negative electrode mixture layer 22 was to be formed and the area where the negative electrode mixture layer 22 was not to be formed were formed.

[0061] <Separator 30> The separator 30 was a PE (polyethylene) single layer type produced by wet biaxial stretching, with a thickness of 25 μm. It was cut to a predetermined size.

[0062] <Positive terminal 50, negative terminal 60> The positive electrode terminal 50 was made of a 0.3 mm thick aluminum sheet A1050-H cut to a specified size, with a 0.15 mm thick resin sealant attached to a portion of it. The negative electrode terminal 60 was made of a 0.3 mm thick copper sheet C1020-O plated with a 2-3 μm thick matte nickel coating and a 0.15 mm thick resin sealant attached to a portion of it. The resin sealants for the positive electrode terminal 50 and negative electrode terminal 60 were configured to cover portions of the aluminum sheet and copper sheet. This resin sealant was welded to the heat-sealed layer of the aluminum laminate packaging material (exterior material 70) by applying heat. The resin sealant was also provided with through-holes of any size, shape, and number (rectangular, round, or various other shapes) that did not contact the edges of the resin sealant.

[0063] <Non-aqueous electrolyte 40> The non-aqueous electrolyte 40 used was an electrolytic solution prepared by adding 3 wt % of vinylene carbonate (VC) to 30 / 70 vol % of ethylene carbonate (EC) and dimethyl carbonate (DMC) as a solvent, with 1.0 M of LiPF6 as a lithium salt.

[0064] <Exterior Material 70> A laminated exterior material having a heat-sealing layer (inner layer), a metal foil layer, and a protective layer (outer layer) laminated in this order was used as the exterior material 70. Specifically, the inner layer was made of a polyolefin resin with a thickness of 80 μm, the metal layer was made of aluminum foil with a thickness of 40 μm, and the outer layer was made of PET (polyethylene terephthalate), resulting in a laminated exterior material with a total thickness of 153 μm. The positive electrode 10, the negative electrode 20, and the separator 30 are stacked one on top of the other, and an embossment adjusted to a predetermined depth is processed in the portion where the positive electrode composite layer 12 of the positive electrode 10 and the negative electrode composite layer 22 of the negative electrode 20 are to be accommodated. At the same time, terrace portions 90 are formed in which the non-formed portion of the positive electrode composite layer 12 of the positive electrode 10 and the non-formed portion of the negative electrode composite layer 22 of the negative electrode 20 are to be accommodated. In the portion where the positive electrode terminal 50 and the negative electrode terminal 60 are to be exposed, through holes are formed in any size, shape, and number (rectangular, round, and various other shapes can be accommodated) that match the through holes in the sealant and do not deviate from the range of the heat-sealed portion, thereby obtaining a first opening 71 and a second opening 72.

[0065] <Assembly of Laminated Lithium-Ion Secondary Battery 100> 29 sheets of positive electrodes 10 and 30 sheets of negative electrodes 20 were punched to a predetermined size, and separators 30 were cut to a predetermined size to form a laminated element, with the separators 30 interposed between the alternately stacked positive electrodes 10 and negative electrodes 20. The battery capacity of this laminated element was approximately 14 Ah.

[0066] A positive electrode terminal 50 and a negative electrode terminal 60 are welded to the non-formed portions of the positive electrode current collector 11 and the negative electrode current collector 21 of the laminated element using an ultrasonic welding machine (a two-head welding machine manufactured by Sonomac). The welding position can be such that the positive electrode terminal 50 and the negative electrode terminal 60 are positioned at half the number of stacked layers of the non-formed portions of the positive electrode current collector 11 and the negative electrode current collector 21, or at the bottom. Weld marks (first welded portion 54, second welded portion 64) are formed in the non-formed portions of the positive electrode 10 and the negative electrode 20. After welding, protective tape is applied to the weld marks to prevent unevenness or burrs from the weld marks from damaging the heat-sealed layer of the laminate exterior material. The protective tape preferably has a polypropylene or polyimide base material and an acrylic adhesive.

[0067] The laminated element with the positive electrode terminal 50 and the negative electrode terminal 60 welded to it was sandwiched between laminate exterior materials, and the portions of the laminate exterior material with through holes (first opening 71, second opening 72) were overlapped with the through hole portions (first exposed portion 52, second exposed portion 62) of the resin sealant of the positive electrode terminal 50 and the negative electrode terminal 60, and the three edge sides of the exterior material 70 were heat-sealed except for the portion that would become the injection port for injecting the non-aqueous electrolyte 40. Basically, the manufacturing method can follow that of a conventional laminate-type lithium-ion battery.

[0068] A non-aqueous electrolyte 40 was injected from the end that remained unsealed, and the battery was vacuum sealed to obtain a pre-initial charging laminated lithium ion secondary battery 100. After that, predetermined initial charging, degassing, and activation steps are performed to obtain a usable laminated lithium ion secondary battery 100.

[0069] [Electricity storage device] Next, one embodiment of the power storage device of the present invention will be described. The power storage device of the present invention includes the laminated lithium-ion secondary battery of the present invention described above. For example, the power storage device may include a battery module 300, 310 including a laminated lithium-ion secondary battery 100, 100a to 100c, or a battery pack. In addition to these battery modules and battery packs, the power storage device may also be any device with a general configuration, and may include a battery monitoring and control unit or system such as a BMU (Battery Management Unit) or BMS (Battery Management System).

[0070] As described above, the present invention enables the miniaturization and space-saving of power storage devices including battery modules and battery packs, and the increase in battery capacity, which was not possible with conventional laminated lithium-ion secondary batteries. Furthermore, by eliminating the need to process tab terminals, the manufacturing process for battery modules and power storage devices can be simplified. The inventions described in the original claims of this application are as follows: [1] a positive electrode having a positive electrode current collector and a positive electrode mixture layer; a negative electrode having a negative electrode current collector and a negative electrode mixture layer; a separator that insulates the positive electrode and the negative electrode; a non-aqueous electrolyte; a positive electrode terminal in contact with the positive electrode current collector; a negative electrode terminal in contact with the negative electrode current collector; an exterior material made of a laminate film having a heat-sealing layer and a metal foil layer, the exterior material containing the positive electrode, the negative electrode, the separator, the non-aqueous electrolyte, the positive electrode terminal, and the negative electrode terminal; A laminated lithium ion secondary battery comprising: the positive electrode terminal has a positive electrode contact portion in contact with the positive electrode current collector, a first exposed portion exposed to the outside of the laminated lithium ion secondary battery, and a first sealant portion fused to the heat-sealing layer of the exterior material, the negative electrode terminal has a negative electrode contact portion in contact with the negative electrode current collector, a second exposed portion exposed to the outside of the laminate-type lithium ion secondary battery, and a second sealant portion fused to the heat-sealing layer of the exterior material, the exterior material has a first opening that exposes the first exposed portion to the outside and a second opening that exposes the second exposed portion to the outside, the first sealant portion surrounds at least a portion of the outer periphery of the first exposed portion, the second sealant portion surrounds at least a portion of the outer periphery of the second exposed portion, The positive electrode terminal and the negative electrode terminal do not have tab portions protruding from the exterior material. Laminated lithium-ion secondary battery. [2] The laminated lithium-ion secondary battery according to [1], wherein the exterior material has a heat-sealed portion formed by stacking two of the laminate films so that their heat-sealed layers face each other and heat-sealing them, and the first exposed portion and the second exposed portion are exposed from the heat-sealed portion. [3] The laminated lithium-ion secondary battery [1], wherein the exterior material is formed by folding one sheet of the laminate film at a folding portion and heat-sealing three sides of the opening to form a heat-sealed portion, the first opening and the second opening are provided on the side where the folding portion is located, and the inside of the exterior material is heat-sealed to the first sealant portion and the second sealant portion. [4] The laminated lithium-ion secondary battery of [1] or [3], wherein either or both of the first exposed portion of the positive electrode terminal and the second exposed portion of the negative electrode terminal have an end on one side of the laminated lithium-ion secondary battery or on a side of the laminated lithium-ion secondary battery that is closer to the inside of the battery than the one side of the laminated lithium-ion secondary battery, and the end is not surrounded by the first sealant portion and the second sealant portion. [5] The laminated lithium ion secondary battery according to any one of [1] to [4], wherein the positive electrode terminal and the negative electrode terminal are built into the exterior material without being bent. [6] a positive electrode terminal contact portion that contacts the positive electrode contact portion of the positive electrode current collector; a negative electrode terminal contact portion that contacts the negative electrode contact portion of the negative electrode current collector; the positive electrode contact portion of the positive electrode terminal; the negative electrode contact portion of the negative electrode terminal; The laminated lithium-ion secondary battery according to any one of [1] to [5], which has a terrace portion having therein. [7] A laminated lithium-ion secondary battery according to any one of [1] to [6], having a battery capacity of 1 Ah or more. [8]

[0013] A power storage device comprising the laminated lithium ion secondary battery according to any one of [1] to [7]. [Explanation of symbols]

[0071] REFERENCE SIGNS LIST 10 positive electrode, 11 positive electrode current collector, 12 positive electrode composite layer, 13 positive electrode terminal contact portion, 20 negative electrode, 21 negative electrode current collector, 22 negative electrode composite layer, 23 negative electrode terminal contact portion, 30 separator, 40 non-aqueous electrolyte, 50, 50a, 50b, 50d positive electrode terminal, 51 positive electrode contact portion, 52, 52a, 52b, 52d first exposed portion, 53 first sealant portion, 54 first welded portion, 60, 60a, 60b, 60d negative electrode terminal, 61 negative electrode contact portion, 62, 62a, 62b, 62d second exposed portion, 63... second sealant portion, 64... second welded portion, 70, 70a, 70d, 270... outer casing material, 71, 71a, 71b, 71c, 71d... first opening, 71e... one end of opening, 72, 72a, 72b, 72c, 72d... second opening, 72e... one end of opening, 73, 73a, 73d, 273... heat-sealed portion, 74, 74d... folded portion, 80, 80a, 80b, 80d... electrode assembly, 90... terrace portion, 100, 100a, 100b, 100c, 100d, 200... laminated lithium ion secondary battery, 210... positive electrode tab terminal, 220···Negative electrode tab terminal, 300, 310, 350···Battery module

Claims

1. a positive electrode having a positive electrode current collector and a positive electrode mixture layer; a negative electrode having a negative electrode current collector and a negative electrode mixture layer; a separator that insulates the positive electrode and the negative electrode; a non-aqueous electrolyte; a positive electrode terminal connected to the positive electrode current collector; a negative electrode terminal connected to the negative electrode current collector; an exterior material having a heat-sealed portion formed by folding a sheet of laminate film having a heat-sealing layer and a metal foil layer and heat-sealing the heat-sealing layers to each other along three open peripheral edges excluding the folded portion, the exterior material housing the positive electrode, the negative electrode, the separator, the non-aqueous electrolyte, the positive electrode terminal, and the negative electrode terminal; A laminated lithium ion secondary battery comprising: one end of the positive electrode terminal is connected to the positive electrode current collector, and the other end extends into the folded portion of the exterior material; a first sealant portion located within the folded portion of the exterior packaging material and interposed between the positive electrode terminal and the thermal seal layer by being fused to the thermal seal layer; one end of the negative electrode terminal is connected to the negative electrode current collector and the other end extends into the folded portion of the exterior material; a second sealant portion located within the folded portion of the exterior packaging material and interposed between the negative electrode terminal and the thermal seal layer by being fused to the thermal seal layer; the exterior material includes a first opening provided to form a first exposed portion that exposes to the outside a portion of the positive electrode terminal covered by the folded portion and the first sealant portion, and a portion of the positive electrode terminal located in the first exposed portion functions as a positive electrode tab, The exterior material includes a second opening provided to form a second exposed portion that exposes to the outside a portion of the negative electrode terminal that is covered with the folded portion and the second sealant portion, and the portion of the negative electrode terminal located in the second exposed portion functions as a negative electrode tab.

2. 2. The laminated lithium-ion secondary battery according to claim 1, wherein one or both of the first exposed portion of the positive electrode terminal and the second exposed portion of the negative electrode terminal have an end portion on one side of the laminated lithium-ion secondary battery or on a side closer to the inside of the battery than the one side of the laminated lithium-ion secondary battery, and the end portion is not surrounded by the first sealant portion and the second sealant portion.

3. 3. The laminated lithium ion secondary battery according to claim 1, wherein the positive electrode terminal and the negative electrode terminal are housed in the exterior material without being bent.

4. The laminated lithium ion secondary battery according to any one of claims 1 to 3, having a battery capacity of 1 Ah or more.

5. An electricity storage device comprising the laminated lithium ion secondary battery according to any one of claims 1 to 4.

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