JP2023044966A - Laminated lithium ion secondary battery and power storage device - Google Patents

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

The present invention relates to a laminate type lithium ion secondary battery and a power storage device.

Secondary batteries as power storage devices are widely used as power sources for electronic devices such as mobile phones and IT devices, as well as for replacing primary batteries. In particular, secondary batteries such as lithium-ion secondary batteries are being applied to electric vehicles and large consumer and industrial electrical equipment such as power supply units. Intentional use is common. In particular, along with miniaturization, weight reduction, and various changes in shape, laminated exterior materials, which are made by bonding resin films to both sides of a metal foil with an adhesive, are being used in place of conventionally used metal exteriors. is increasing

Japanese Patent No. 6632831 Japanese Patent No. 6661459 Japanese Patent No. 6666096

A conventional laminated lithium-ion secondary battery using a laminated exterior material has a basic structure in which a tab metal terminal protrudes from at least one end of the battery. Therefore, when connecting laminated lithium-ion secondary batteries to each other with a bus bar or the like, extra unusable space is created in the structure of the output terminal portion of a battery module or battery pack composed of multiple batteries. , there is a problem that the structural flexibility of the device provided with the battery is impaired.

In addition, the metal tab terminals protruding from the laminated lithium-ion secondary battery require additional processing such as cutting and bending due to the design of the metal tab terminals for adjusting the length of the tab metal terminals and for joining the metal tab terminals together. Therefore, there is a possibility that the number of processing steps increases and the processing steps become more complicated.

By the way, in Patent Documents 1 to 3, the electrode terminals (tab metal terminals) are formed by exposing the metal foil layer of the exterior material to reduce the size and weight. It is considered to be difficult to apply to laminated lithium-ion batteries, which require a capacity of several Ah to draw current from a large area, thick and multi-layered electrodes.

In view of the above, in the present invention, it is possible to reduce the size and space of power storage devices including battery modules and battery packs, and to increase the capacity of batteries, which could not be achieved with conventional laminated lithium ion secondary batteries. It is an object of the present invention to provide a laminate-type lithium ion secondary battery and a power storage device that can

In order to solve the above problems, the laminated lithium ion secondary battery of the present invention includes 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, and A laminate film having 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, a heat-sealable layer and a metal foil layer A laminate type lithium ion secondary battery comprising: the positive electrode, the negative electrode, the separator, the non-aqueous electrolyte, the positive electrode terminal, and the negative electrode terminal. A positive electrode contact portion in contact with a current collector, a first exposed portion exposed to the outside of the laminate type lithium ion secondary battery, and a first sealant portion fused to the thermal adhesive layer of the exterior material. The negative electrode terminal includes 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 the heat-sealable layer of the exterior material. a second sealant portion, wherein the exterior material includes a first opening that exposes the first exposed portion to the outside; a second opening that exposes the second exposed portion to the outside; wherein 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, and the positive electrode The terminal and the negative electrode terminal are a laminate type lithium ion secondary battery that does not have a tab portion protruding from the exterior material.

According to the present invention, the miniaturization and space saving of power storage devices including battery modules and battery packs, the increase in battery capacity, and the complication of the manufacturing process, which could not be achieved with conventional laminated lithium-ion secondary batteries. It is possible to provide a laminate-type lithium ion secondary battery and a power storage device that can solve the problem.

1 is a schematic perspective view of a laminated lithium ion secondary battery 100 according to one embodiment of the present invention; FIG. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing of the lamination-type lithium ion secondary battery 100, Fig.2 (a) is AA sectional drawing of FIG. 1, FIG.2(b) is BB sectional drawing of FIG. 3(a) is a positive electrode terminal 50, FIG. 3(b) is a negative electrode terminal 60, and FIG. (c) shows the electrode assembly 80, and FIG. 3(d) shows the laminated lithium ion secondary battery 100. As shown in FIG. 4A and 4B are schematic front views of a positive electrode terminal 50a, a negative electrode terminal 60a, an electrode assembly 80a, and a laminate-type lithium ion secondary battery 100a that are different from those in FIG. is the negative electrode terminal 60a, FIG. 4(c) is the electrode assembly 80a, and FIG. 4(d) is the laminate type lithium ion secondary battery 100a. FIG. 5A is a schematic front view of a positive electrode terminal 50b, a negative electrode terminal 60b, an electrode assembly 80b, and a laminated lithium ion secondary battery 100b in a mode different from FIGS. b) is a negative electrode terminal 60b, FIG. 5(c) is an electrode assembly 80b, and FIG. 5(d) is a laminate type lithium ion secondary battery 100b. FIG. 6 is a schematic front view of a laminated lithium-ion secondary battery 100c that is different from FIGS. 3 to 5; It is a schematic front view of a positive electrode terminal 50d, a negative electrode terminal 60d, an electrode assembly 80d, and a laminate type lithium ion secondary battery 100d in a mode different from FIGS. b) is a negative electrode terminal 60d, FIG. 7(c) is an electrode assembly 80d, and FIG. 7(d) is a laminate type lithium ion secondary battery 100d. 1 is a schematic front view of a conventional laminated lithium ion secondary battery 200; FIG. FIG. 8A 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. is the battery module 350, FIG. 8(b) is the battery module 300, and FIG. 8(c) is the battery module 310. FIG.

An embodiment of the laminate type lithium ion secondary battery and power storage device of the present invention will be described below with reference to the drawings. However, the present invention is not limited to the following one embodiment.

[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 invention. 2A and 2B are schematic cross-sectional views of the laminated lithium-ion secondary battery 100, FIG. 2A is a cross-sectional view along AA in FIG. 1, and FIG. 2B is a cross-sectional view along BB in FIG. 3A and 3B are schematic front views of the positive electrode terminal 50, the negative electrode terminal 60, the electrode assembly 80, and the laminated lithium ion secondary battery 100. FIG. A negative electrode terminal 60, FIG. 3(c) shows an electrode assembly 80, and FIG. 3(d) shows a laminated lithium ion secondary battery 100. As shown in FIG.

A laminate type 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 70 .

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

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 lithium secondary batteries, such as a lithium-containing metal oxide. For example, lithium cobalt composite oxide (e.g. LiCoO ₂ ), lithium manganese composite oxide (e.g. LiMnO ₂ , LiMn ₂ O ₄ , LiMn ₂ O ₃ ), lithium nickel composite oxide (e.g. LiNiO ₂ ), lithium cobalt iron composite oxide (eg LiCo _0.5 Fe _0.5 O ₂ ), lithium nickel cobalt manganese composite oxide (eg Li ( _Nix Co _y Mn _1-x-y )O ₂ (0<x<1, 0<y<1)), Lithium-iron-phosphorus composite oxide (for example, LiFePO ₄ ) and the like are included.

The positive electrode current collector 11 is, for example, aluminum or an aluminum alloy. Materials for the positive electrode current collector include, for example, aluminum foil, meshes of metals such as aluminum, porous metals, expanded metals, and punched metals.

The conductive material is not particularly limited, and known or commercially available materials can be used. Examples thereof include carbon black such as acetylene black and Ketjen black, carbon nanotube, carbon fiber, activated carbon, and graphite.

The binder is not particularly limited, and any known or commercially available one 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 and the like.

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

The negative electrode active material is not particularly limited as long as it is a material capable of dissolving or depositing metals or inserting/extracting metal ions. Examples of negative electrode active materials include lithium metal, carbon-based materials, silicon, silicon alloys, and tin. A carbonaceous material capable of intercalating and deintercalating lithium ions is, for example, powdery or fibrous graphite.

The negative electrode current collector 21 is not particularly limited, and a known or commercially available one can be used. Examples of negative electrode current collectors include rolled foils and electrolytic foils made of copper or copper alloys.

(Separator 30)
The separator 30 insulates the positive electrode 10 and the negative electrode 20, and may be made of, for example, polyolefin resin such as polyethylene resin or polypropylene resin, polytetrafluoroethylene resin, stretched film of cellulose or polyimide, microporous film, or non-woven fabric. can. Stretched films, microporous membranes or non-woven fabrics may be single-layered or multi-layered. The separator may particularly preferably be a microporous polyethylene membrane. The separators 30 include a separator that is cut one by one between the positive electrode 10 and the negative electrode 20 and arranged to insulate, and a separator that is a zigzag-shaped separator that insulates the plurality of positive electrodes 10 and the plurality of negative electrodes 20. is mentioned.

(Non-aqueous electrolyte 40)
The non-aqueous electrolyte 40 includes a non-aqueous solvent and an electrolyte when in liquid form.

The non-aqueous solvent preferably contains cyclic carbonate and 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), ethylmethyl carbonate (EMC), and the like.

The electrolyte is not particularly limited, and a lithium salt electrolyte generally used in lithium secondary batteries can be used. For example _{, LiPF6} , _LiBF4 , _LiAsF6 , LiClO4, _LiCF3SO3 , LiN( _{CF3SO2 ) ( C4F4SO2 )} , LiN( _{CmF2m + 1SO2 )} ( _{CnF2n +1SO 2} ) (m and n are integers of 1 or more), LiC( _{CpF2p + 1SO2} ) ( _{CqF2q + 1SO2} ) ( _{CrF2r + 1SO2} ) (p, q, and r are integers of 1 or more) , lithium difluoro(oxalato)borate, and the like can be used. These electrolytes may be used singly or in combination of two or more. Moreover, it is desirable that the electrolyte dissolves in the non-aqueous solvent at a concentration of 0.1 to 1.5 mol/L, preferably 0.5 to 1.5 mol/L.

(Positive terminal 50)
The positive terminal 50 is a terminal in contact with the positive current collector 11 . As shown in FIG. 3A, the positive electrode terminal 50 includes a positive electrode contact portion 51 in contact with the positive electrode current collector 11, a first exposed portion 52 exposed to the outside of the laminated lithium ion secondary battery 100, and an exterior material. It has a first sealant portion 53 that is fused with the heat-sealable layer 70 . The first sealant portion 53 surrounds the outer circumference of the first exposed portion 52 .

(Negative terminal 60)
The negative electrode terminal 60 is a terminal in contact with the negative electrode current collector 21 . As shown in FIG. 3B, the negative electrode terminal 60 includes 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 an exterior material. It has a second sealant part 63 that is fused with the heat-sealable layer 70 . The second sealant portion 63 surrounds the outer circumference of the second exposed portion 62 .

(Welding method and welding width of laminated lithium-ion secondary battery)
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. Welding methods include ultrasonic welding, resistance welding, and fiber laser welding. When the areas of the first exposed portion 52 and the second exposed portion 62 are each 2000 μm ² or more and each side is 50 μm or more, the tab terminal and the bus bar can be welded by fiber laser welding. However, when using other welding methods, and from the viewpoint of welding strength, heat generation suppression, input/output performance, etc., it is preferable to secure a wider area and a longer length of one side. On the other hand, in order 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 lateral direction of the first sealant portion 53 and the second sealant portion 63 is 10 mm or less. .

The areas and shapes of the first exposed portion 52 and the second exposed portion 62 may be the same or different. Further, the area, shape, and position of each exposed portion may be different between the front and back of the laminated lithium ion secondary battery 100 in the plane direction of each exposed portion. Both the first exposed portion 52 and the second exposed portion 62 may be present on both the front and back sides of the laminate type lithium ion secondary battery 100 in the plane direction, or may be present only on one side. The presence of the first exposed portion 52 and the second exposed portion 62 on the front and back sides of the laminate type lithium ion secondary battery 100 in the plane direction may or may not match.

In addition, the first sealant portion 53 surrounding the first exposed portion 52 and the second sealant portion 63 surrounding the second exposed portion 62 have the smallest widths from the viewpoint of the stability of the fusion work with the exterior material 70. It is preferably 1 mm or more, and more preferably has a width of 5 mm. From the viewpoint of miniaturization of the laminated lithium ion secondary battery 100, the minimum width of the first sealant portion 53 surrounding the first exposed portion 52 and the second sealant portion 63 surrounding the second exposed portion 62 is 10 mm or less. is preferably

Furthermore, from the viewpoint of seal durability and water vapor barrier properties, the fused portion between the exterior material 70 surrounding the first exposed portion 52 and the exterior material 70 surrounding the second exposed portion 62 is the smallest. It is preferably 1 mm or more in width, and more preferably has a width of 5 mm. From the viewpoint of miniaturization of the battery, the minimum width of the fused portion between the exterior material 70 surrounding the first exposed portion 52 and the exterior material 70 surrounding the second exposed portion 62 is 10 mm or less. Preferably.

In addition, the width in the same direction of the fusion-bonded portion between the first sealant portion 53 surrounding the first exposed portion 52 and the exterior material 70 surrounding the first exposed portion 52 is irrespective of the width from the viewpoint of short-circuit prevention. Therefore, it is preferable that the width of the first sealant portion 53 is longer than the width of the fused portion by about 2 to 3 mm, but they may be the same. The same applies to the width of the fused portion between the second sealant portion 63 surrounding the second exposed portion 62 and the exterior material 70 surrounding the second exposed portion 62 .

Although details will be described later, unlike conventional batteries, in the laminated lithium ion secondary battery 100, the positive electrode terminal 50 and the negative electrode terminal 60 do not have a tab portion protruding from the outer packaging material 70, thereby miniaturizing the battery. and increase in battery capacity. In addition, since there is no tab portion, there is no need for additional processing such as cutting or bending the tab portion.

(Exterior material 70)
The exterior material 70 is made of a laminate film having a heat-sealable layer and a metal foil layer, and incorporates 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.

The exterior material 70 has, for example, a bag shape, and accommodates a flat electrode assembly 80 (FIG. 3(c)), which will be described later. A laminate film has a structure in which, for example, a plurality of (for example, two) plastic films are laminated by sandwiching a metal foil such as an aluminum foil as a metal foil layer between the films. One of the two plastic films uses a heat-fusible resin film as a heat-fusible layer. The exterior material 70 is made by stacking two laminate films so that their heat-sealable resin films face each other, interposing the electrode assembly 80 between these laminate films, and surrounding the electrode assembly 80 with two sheets. The electrode assembly 80 is airtightly accommodated by heat-sealing the laminate film portions (the heat-sealed portions 73 in FIG. 3(d)) to each other and sealing the four sides.

The exterior material 70 has a first opening 71 that exposes the first exposed portion 52 of the positive electrode terminal 50 to the outside, and a second opening 72 that exposes the second exposed portion 62 of the negative electrode terminal 60 to the outside. By providing the first opening 71 and the second opening 72, the first exposed portion 52 that is part of the positive electrode terminal 50 and the second exposed portion 62 that is part of the negative electrode terminal 60 can be separated without the tab portion. The first exposed portion 52 and the second exposed portion 62 may be connected by a bus bar or the like in place of the tab portion. At this time, it is preferable that the first exposed portion 52 and the second exposed portion 62 are provided in the heat-sealed portion 73 formed by sealing the laminate film by heat-sealing. That is, it is preferable that the first exposed portion 52 and the second exposed portion 62 are exposed from the heat-sealed portion 73 so that the positive electrode terminal 50 and the negative electrode terminal 60 are exposed from the heat-sealed portion 73 . The reason for this is that there is no need to provide a new fused portion in the terrace portion and that the fused position is less likely to shift than in the thick terrace portion.

(Electrode assembly 80)
As shown in FIG. 2A, the electrode assembly 80 has a structure in which a plurality of positive electrodes 10, negative electrodes 20, and separators 30 interposed between the positive electrodes 10 and the negative electrodes 20 are laminated such that the negative electrodes 20 are positioned at the outermost layers. have The positive electrode 10 is composed of a positive electrode current collector 11 and positive electrode mixture layers 12 formed on both sides of the current collector 11 . The negative electrode 20 is composed of a negative electrode current collector 21 and negative electrode mixture layers 22 formed on both sides of the current collector 21 . The outermost negative electrode 20 may not include the negative electrode mixture layer 22 on the surface of the negative electrode current collector 21 facing the exterior material.

In the positive electrode 10, the positive electrode current collectors 11 extend from the positive electrode composite material layer 12 to the positive electrode terminal 50, and the positive electrode current collectors 11 are bundled at the tip end side in the outer packaging material 70 so as to be joined to each other. The positive electrode contact portion 51 of the terminal 50 is welded to the first welding portion 54 (see FIG. 3(c)).

In the negative electrode 20, the negative electrode current collectors 21 extend from the negative electrode mixture layer 22 to the negative electrode terminal 60, and the respective negative electrode current collectors 21 are bundled at the tip end side in the outer packaging material 70 so as to be joined to each other. The negative electrode contact portion 61 of the terminal 60 is welded to the second welding portion 64 (see FIG. 3(c)).

In addition, the first sealant portion 53 of the positive electrode terminal 50 is heat-sealed to the heat-sealed portion 73 of the exterior material 70 to prevent the non-aqueous electrolyte 40 inside the exterior material 70 from leaking from the first opening 71 . there is

Similarly, in the negative terminal 60, the second sealant portion 63 is heat-sealed to the heat-sealed portion 73 of the exterior material 70 to prevent the non-aqueous electrolyte 40 inside the exterior material 70 from leaking from the second opening 72. I'm in.

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 is, for example, 0.3 mm depending on the capacity and size. As described above, it becomes difficult to bend the positive electrode terminal 50 and the negative electrode terminal 60 accurately. Positioning of the terminal 60 may become difficult. Therefore, especially 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 in the exterior material 70 without being bent. Moreover, even when the battery capacity is less than 1 Ah, there is no problem in that the battery can be incorporated without being bent if bending is unnecessary.

(Terrace section 90)
Laminated lithium ion secondary battery 100 is arranged such that first exposed portion 52 and second exposed portion 62 are exposed from first opening 71 and second opening 72 provided at the same end of package 70. A positive electrode terminal contact portion 13 in contact with the positive electrode contact portion 51 in the positive electrode current collector 11 , a negative electrode terminal contact portion 23 in contact with the negative electrode contact portion 61 in the negative electrode current collector 21 , and the positive electrode contact in the positive electrode terminal 50 . A terrace portion 90 containing the portion 51 and the negative electrode contact portion 61 of the negative electrode terminal 60 may be provided. In this specification, of the electrode assembly including the positive electrode 10, the negative electrode 20, and the separator 30, the non-embossed portions of the laminated outer material face each other, and the positive electrode mixture layer 12 of the positive electrode 10 is not formed. A portion of the storage portion of the lithium-ion secondary battery in which the negative electrode mixture layer 22 non-formed portion of the negative electrode 20 and the negative electrode mixture layer 22 are stored is called a terrace portion.

However, a battery not provided with the terrace portion 90 is also included in the laminated lithium ion secondary battery of the present invention. For example, when the first opening 71 and the second opening 72 are provided at different ends of the exterior material 70, the terrace 90 may not be provided.

<Second embodiment>
FIG. 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 a mode different from that in FIG. Three square first exposed portions 52a and three second exposed portions 62a are provided, and correspondingly, three square first openings 71a and three second square openings 72a are provided. . The number of first exposed portions 52a and second exposed portions 62a is not limited to three, and may be different numbers.

<Third embodiment>
FIG. 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 a mode different from FIGS. Three circular first exposed portions 52b and three second exposed portions 62b are provided, and correspondingly, three circular first openings 71b and three second circular openings 72b are provided. . The number of first exposed portions 52b and second exposed portions 62b is not limited to three, and may be different numbers.

<Fourth Embodiment>
FIG. 6 is a schematic front view of a laminated lithium-ion secondary battery 100c that is different from FIGS. In the first to third embodiments, the four sides of the two laminate films are heat-sealed to form the exterior material 70, but in the fourth embodiment, one laminate film is folded at the folding portion 74 to form the opening. The exterior material 70a is formed as a heat-sealed portion 73a by heat-sealing three regions indicated by dotted lines. The bent portion 74 is preferably positioned so as to bisect the laminate film. This is because if the folded portion 74 is positioned to divide the laminate film into two halves, there is no non-overlapping portion of the laminate film (hereinafter referred to as surplus portion). Even if the bent portion is not at a position that bisects the laminate film, it is preferable to adjust the position so that the excess portion is finally cut to bisect the laminate film. In addition, the first opening 71c and the second opening 72c are provided on the side where the bent portion 74 is located, and the interior of the exterior material 70a is closed so that the non-aqueous electrolyte 40 contained in the exterior material 70 does not leak to the outside. It is heat-sealed with the first sealant portion 53 and the second sealant portion 63 . In this embodiment, one side of the heat-sealed portion of the exterior material can be omitted, and a more space-saving battery can be provided.

<Fifth Embodiment>
FIG. 7 is a schematic front view of a positive electrode terminal 50d, a negative electrode terminal 60d, an electrode assembly 80d, and a laminate type lithium ion secondary battery 100d in a mode different from FIGS. In the first to fourth embodiments, the four sides of the first exposed portions 52, 52a, 52b and the second exposed portions 62, 62a, 62b are respectively heat-sealed. As in the embodiment, one sheet of laminate film is folded at the bending portion 74d, and three regions of the opening indicated by dotted lines are heat-sealed to form the heat-sealing portion 73d of the exterior material 70a. One end 71e or 72e of at least one of the first opening 71d and the second opening 72d is closest to the first opening 71d and the second opening 72d among the sides of the laminate type lithium ion secondary battery 100d. It is arranged along a nearby side (for example, the bent portion 74d) or inside the one side.

In the present embodiment, since 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, the laminated lithium ion secondary battery 100d is completed. can be easily processed, and the positive electrode terminal 50d and the negative electrode terminal 60d do not protrude. In addition, as in the fourth embodiment, if the laminated lithium ion secondary battery 100d has the bent portion 74d, further space saving can be expected.

<Conventional form>
FIG. 8 is a schematic front view of a conventional laminated lithium ion secondary battery 200. FIG. The exterior material 270 does not have an opening, but is heat-sealed on four sides to form a heat-sealed portion 273 , and the positive electrode tab terminal 210 and the negative electrode tab terminal 220 protrude from the exterior material 270 .

The electrode assembly incorporated in the exterior material 270 may be the same as the electrode assembly 80 of the laminate type lithium ion secondary battery 100, and instead of the positive electrode terminal 50 and the negative electrode terminal 60, the positive electrode tab terminal 210 and the negative electrode tab A terminal 220 is provided.

<Comparison with conventional form>
Next, with reference to FIG. 9, the effects obtained by the laminated lithium ion secondary battery 100 of the present invention will be described by comparing with the conventional laminated lithium ion secondary battery 200. FIG.

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

A battery module 350 of FIG. 9A is a schematic side view showing a state in which three laminated lithium ion secondary batteries 200 are arranged in parallel within a housing 400 . A battery module 300 of FIG. 9B for comparison is a schematic side view showing a state in which three laminated lithium ion secondary batteries 100 are arranged in parallel within a housing 410 . Although the battery module 300 and the battery module 350 have different terminals, the same electrode assembly 80 is built in. Therefore, the performance as a battery module is the same. It is a module.

That is, in the case of the same performance as a battery module, by using the laminated lithium ion secondary battery 100, it is possible to make the ionization module smaller than when using the conventional laminated lithium ion secondary battery 200. . Note that this effect is not limited to the first embodiment, and can be similarly obtained in the batteries of the second to fourth embodiments.

Next, the battery module 310 of FIG.8(c) compared with FIG.9(a) is demonstrated. A battery module 310 is a schematic side view showing a state in which three laminated lithium ion secondary batteries 100 are arranged in parallel in the same housing 400 as in FIG. 9(a). In the case of the battery module 310 , the electrode assembly 80 that is larger than that in the case of the battery module 350 is built into the exterior material 70 . Therefore, although the two have the same size as battery modules, the battery module 310 has a larger battery capacity than the battery module 350 . For example, when 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) is 17 Ah. It can be 1.2 times larger.

That is, when the battery module has the same size, the use of the laminated lithium ion secondary battery 100 enables the battery module to have higher performance than the conventional laminated lithium ion secondary battery 200. be. Note that this effect is not limited to the first embodiment, and can be similarly obtained in the batteries of the second to fourth embodiments.

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

<Positive electrode 10>
90 parts by mass of LiFePO ₄ (lithium iron phosphate), 5 parts by mass of PVDF (polyvinylidene fluoride), and 5 parts by mass of carbon black as a conductive agent were dissolved in N-methyl-2-pyrrolidone (NMP) as a solvent. A positive electrode mixture slurry was prepared by dispersing. This positive electrode mixture slurry was applied to both surfaces of a 20 μm aluminum foil (positive electrode current collector 11 ), dried, and then rolled to obtain a positive electrode 10 . A positive electrode was obtained by punching into a predetermined shape and size with a mold so that the positive electrode mixture layer 12 was formed and not formed.

<Negative electrode 20>
98 parts by weight of graphite, 1 part by weight of CMC (carboxymethyl cellulose), 1 part by weight of SBR (styrene-butadiene rubber), and ion-exchanged water as a solvent were dispersed to prepare a negative electrode mixture slurry. A negative electrode 20 was obtained by coating and drying both sides of a 10 μm copper foil (negative electrode current collector 21 ), followed by rolling. A negative electrode was obtained by punching into a predetermined shape and size with a mold so that a portion where the negative electrode mixture layer 22 was formed and a portion where the negative electrode mixture layer 22 was not formed.

<Separator 30>
A PE (polyethylene) single layer type prepared by a wet biaxial stretching method and having a thickness of 25 μm was used. A separator 30 was obtained by cutting into a predetermined size.

<Positive terminal 50/negative terminal 60>
As the positive electrode terminal 50, an aluminum sheet A1050-H having a thickness of 0.3 mm cut into a predetermined size and having a resin sealant material having a thickness of 0.15 mm attached to a part thereof was used. The negative electrode terminal 60 is a copper sheet C1020-O with a thickness of 0.3 mm, which is matte-plated with nickel with a thickness of 2 to 3 μm, and a resin sealant material with a thickness of 0.15 mm is partially attached. The resin sealants of the positive terminal 50 and the negative terminal 60 are configured to cover portions of the aluminum sheet and the copper sheet. This resin sealant is welded by applying heat to the heat-adhesive layer of the Al-laminated packaging material, which is the exterior material 70 . In addition, the resin sealant is provided with through-holes of any size, shape, and number (rectangular, round, and various shapes can be accommodated) that do not touch the edges of the resin sealant.

<Non-aqueous electrolyte 40>
As the non-aqueous electrolyte 40, 1.0 M of LiPF ₆ as a lithium salt, 30/70 vol% of ethylene carbonate (EC) and dimethyl carbonate (DMC) as solvents, and 3 wt% of vinylene carbonate (VC) were added to prepare an electrolytic solution. liquid was used.

<Exterior material 70>
As the exterior material 70, a laminated exterior material was used in which a heat-sealable layer (inner layer), a metal foil layer, and a protective layer (outer layer) were laminated in this order. Specifically, the inner layer is made of polyolefin resin of 80 μm, the metal layer is made of aluminum foil of 40 μm, and the outer layer is made of PET (polyethylene terephthalate) with a total thickness of 153 μm. It is wood. The positive electrode 10, the negative electrode 20, and the separator 30 are laminated to each other, and the portions where the positive electrode mixture layer 12 of the positive electrode 10 and the negative electrode mixture layer 22 of the negative electrode 20 are accommodated are embossed to a predetermined depth, and at the same time, A terrace portion 90 is formed to accommodate a portion of the positive electrode 10 where the positive electrode mixture layer 12 is not formed and a portion of the negative electrode 20 where the negative electrode mixture layer 22 is not formed. The first opening 71 and the second opening 71 and the second opening 71 are formed by providing through-holes of any size, shape, and number (rectangular, round, and various shapes can be accommodated) that match the through-holes of the sealant and do not deviate from the range of the heat-sealed portion. An opening 72 was obtained.

<Assembly of Laminated Lithium Ion Secondary Battery 100>
29 sheets of the positive electrode 10 and 30 sheets of the negative electrode 20 punched into a predetermined size, and the separator 30 cut to a predetermined size are alternately laminated, and the separator 30 is sandwiched between the positive electrode 10 and the negative electrode 20. was interposed to obtain a laminated element. This laminated element has a battery capacity of about 14 Ah.

The positive electrode terminal 50 and the 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, respectively, by an ultrasonic welding machine (two-head type welding machine manufactured by Sonomac). Weld using The welding position is such that the positive electrode current collector 11 and the negative electrode current collector 21 are positioned at half the number of layers in the non-formed portion of the mixture layer, or the positive electrode terminal 50 and the negative electrode terminal 60 are placed at the bottom. , can be welded. Welding marks (first welded portion 54 and second welded portion 64) are formed in portions of positive electrode 10 and negative electrode 20 where mixture layers are not formed. After welding, the weld marks are covered with a protective tape so that the weld marks and burrs do not damage the heat-bonded layer of the laminate exterior material. The protective tape preferably has a base material of polypropylene or polyimide and an adhesive of acrylic type.

The laminated element with the positive electrode terminal 50 and the negative electrode terminal 60 welded together is sandwiched between laminated outer materials, and the portions where the through holes (the first opening 71 and the second opening 72) are formed in the laminated outer material are the positive electrode terminal 50 and the negative electrode terminal. The three side edges of the exterior material 70 other than the portion that overlaps the through-hole portions (the first exposed portion 52 and the second exposed portion 62) of the resin sealant 60 and become the injection port for injecting the non-aqueous electrolyte 40. heat-sealed. Basically, the manufacturing method of a conventional laminate type lithium ion battery can be followed.

A non-aqueous electrolyte 40 was injected from one end that was left unsealed and vacuum sealed to obtain a laminated lithium ion secondary battery 100 before initial charging. After that, predetermined initial charging steps, degassing steps, and activation steps are performed to obtain a laminate type lithium ion secondary battery 100 that can be used.

[Power storage device]
Next, one embodiment of the power storage device of the present invention will be described. A power storage device of the present invention includes the laminate-type lithium ion secondary battery of the present invention described above. Examples include battery modules 300 and 310 including laminated lithium ion secondary batteries 100 and 100a to 100c, and power storage devices including battery packs. As the power storage device, in addition to these battery modules and battery packs, any device having a general configuration may be used. can be

As described above, with the present invention, it is possible to reduce the size and space of power storage devices including battery modules and battery packs, and to increase the capacity of batteries, which could not be achieved with conventional laminated lithium-ion secondary batteries. is. In addition, since there is no need to process the tab terminals, it is possible to eliminate complication of the manufacturing process of the battery module and the power storage device.

DESCRIPTION OF SYMBOLS 10... Positive electrode 11... Positive electrode collector 12... Positive electrode mixture layer 13... Positive electrode terminal contact part 20... Negative electrode 21... Negative electrode collector 22. Negative electrode mixture 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 weld portion 70, 70a, 70d, 270 Exterior material , 71, 71a, 71b, 71c, 71d First opening 71e One end of opening 72, 72a, 72b, 72c, 72d Second opening 72e Opening one end of 73, 73a, 73d, 273... heat-sealed portion 74, 74d... bent 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 (8)

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-sealable layer and a metal foil layer and 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 includes 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 exposed portion that is fused with the heat-sealable layer of the exterior material. 1 a sealant portion;
The negative electrode terminal includes a negative electrode contact portion that is in contact with the negative electrode current collector, a second exposed portion that is exposed to the outside of the laminate type lithium ion secondary battery, and a second portion that is fused with the heat-sealable layer of the exterior material. 2 a sealant portion;
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 a tab portion protruding from the exterior material,
Laminated lithium-ion secondary battery. The exterior material has a heat-sealed portion formed by stacking and heat-sealing the two laminate films so that the heat-sealing layers thereof face each other, and includes the first exposed portion and the second exposed portion. 2. The laminate type lithium ion secondary battery according to claim 1, wherein the portion is exposed from the heat-sealed portion. The exterior material has a heat-sealed portion formed by bending one sheet of the laminate film at a folding portion and heat-sealing three sides of the opening, and the first opening and the second opening are 2. The laminate type lithium ion secondary battery according to claim 1, wherein the exterior material is provided on the side with the bent portion, and the interior of the exterior material is heat-sealed with the first sealant portion and the second sealant portion. . Either one or both of the first exposed portion of the positive electrode terminal and the second exposed portion of the negative electrode terminal are located on one side of the laminated lithium ion secondary battery or from one side of the laminated lithium ion secondary battery. 4. The laminate type lithium ion secondary battery according to claim 1, wherein the battery has an end portion inside the battery, and the end portion is not surrounded by the first sealant portion and the second sealant portion. 5. The laminate type lithium ion secondary battery according to claim 1, wherein said positive electrode terminal and said negative electrode terminal are built into said exterior material without being bent. a positive electrode terminal contact portion in contact with the positive electrode contact portion of the positive electrode current collector;
a negative electrode terminal contact portion in contact with the negative electrode contact portion of the negative electrode current collector;
the positive electrode contact portion at the positive electrode terminal;
the negative electrode contact portion at the negative electrode terminal;
6. The laminate-type lithium ion secondary battery according to claim 1, comprising a terrace portion in which is embedded. The laminate type lithium ion secondary battery according to any one of claims 1 to 6, wherein the battery capacity is 1 Ah or more. A power storage device comprising the laminated lithium ion secondary battery according to any one of claims 1 to 7.

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