Secondary battery and manufacturing method thereof

Abstract

Provided are: a secondary battery in which the load applied to a lead is reduced; and a method for manufacturing the secondary battery. A secondary battery 100 includes: an electrode assembly 10; an exterior body 50 that has a space therein for storing the electrode assembly 10; a terminal member 60 that is electrically connected to the electrode assembly 10; and a lead 40 that electrically connects the terminal member 60 to the electrode assembly 10. The lead 40 is fixed, with a fixing member, to a surface inside the exterior body 50.

Description

[Technical field]

[0001] The present invention relates to a secondary battery and a manufacturing method thereof, and more particularly to a secondary battery including an electrode assembly composed of electrode constituent layers including a positive electrode, a negative electrode, and a separator, and a manufacturing method thereof. [Background technology]

[0002] Secondary batteries can be repeatedly charged and discharged, and are used in a variety of applications. For example, secondary batteries are used in mobile devices such as mobile phones, smartphones, and notebook computers. Such secondary batteries are disclosed in Patent Document 1 and Patent Document 2. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5470142 [Patent Document 2] JP 2019-46639 A Summary of the Invention [Problem to be solved by the invention]

[0004] The inventors of the present application realized that there were problems to be overcome in conventional secondary batteries and found it necessary to take measures to address these problems. Specifically, the inventors of the present application found the following problems:

[0005] Patent Document 1 discloses a secondary battery in which an electrode group housed in a battery container and a lid unit are connected via a lead plate. In the manufacturing process of the secondary battery, it is considered to lengthen the lead plate from the viewpoint of facilitating electrical connection between the lead plate and the lid unit. However, in this case, it is not easy to seal the lid unit while housing the lead plate in the battery container. In addition, there is a risk that a load will be applied to the lid unit and / or the electrode group when housing the lead plate in the battery container.

[0006] The present invention has been made in view of the above problems. That is, a main object of the present invention is to provide a secondary battery in which the load applied to the leads is reduced, and a method for manufacturing the secondary battery. [Means for solving the problem]

[0007] The secondary battery according to the present invention comprises: an electrode assembly; an exterior body having an internal space for accommodating the electrode assembly; a terminal member electrically connected to the electrode assembly; and a lead electrically connecting the terminal member to the electrode assembly; The leads are fixed to the inner surface of the exterior body by a fixing member.

[0008] The manufacturing method according to the present invention further comprises the steps of: A method for manufacturing a secondary battery comprising: an electrode assembly; an exterior body having an internal space for accommodating the electrode assembly; a terminal member electrically connected to the electrode assembly; and a lead electrically connecting the terminal member and the electrode assembly, the lead being fixed to an inner surface of the exterior body by a fixing member, a connecting step of electrically connecting the lead, which is electrically connected to the electrode assembly, to the terminal member; and a fixing step of fixing the leads to the inner surface of the exterior body with a fixing member. Effect of the Invention

[0009] In the secondary battery according to the present invention, the leads that electrically connect the terminal members and the electrode assembly are fixed to the inner surface of the exterior body, and the leads can be stored in the exterior body in a fixed state, thereby reducing the load on the leads. Also, the manufacturing method for a secondary battery according to the present invention includes a fixing step of fixing the leads to the inner surface of the exterior body, so that a secondary battery in which the leads can be easily stored in the exterior body can be manufactured. [Brief description of the drawings]

[0010] [Figure 1]FIG. 1 shows a schematic diagram of an electrode configuration layer, where (a) is a cross-sectional view showing a planar laminated structure, and (b) is a cross-sectional view showing a wound structure. [Diagram 2] FIG. 2 is a cross-sectional view that illustrates a schematic configuration of a secondary battery according to an embodiment of the present invention. [Diagram 3] FIG. 3 is a perspective view of an electrode assembly according to an embodiment of the present invention. [Figure 4] FIG. 4 is a cross-sectional view that typically shows a state in which the internal pressure of the secondary battery has increased and the exterior body has been ruptured. [Diagram 5] FIG. 5 shows schematic diagrams of exemplary forms of secondary batteries, where (a) is a perspective view of a button-type or coin-type secondary battery, and (b) is a perspective view of a square-type secondary battery. [Figure 6] FIG. 6 is a cross-sectional view that illustrates a schematic configuration of a secondary battery according to another embodiment of the present invention. [Figure 7] FIG. 7 is a cross-sectional view that illustrates a schematic configuration of a secondary battery according to another embodiment of the present invention. [Figure 8] 8A to 8C are cross-sectional views showing the steps of manufacturing a secondary battery of the present invention. [Figure 9] 9A to 9C are cross-sectional views showing the steps of manufacturing a secondary battery of the present invention. [Figure 10] 10A to 10C are cross-sectional views showing the steps of manufacturing a secondary battery according to the present invention. [Figure 11] 11A to 11C are cross-sectional views showing the steps of manufacturing a secondary battery according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, a secondary battery according to an embodiment of the present invention will be described in more detail. Although the description will be made with reference to the drawings as necessary, various elements in the drawings are merely shown as schematic and illustrative elements for understanding the present invention, and the appearance or dimensional ratio may differ from the actual ones.

[0012] The "upper and lower directions" and "lower and higher directions" described directly or indirectly in this specification correspond to the upper and lower directions and lower and higher directions in the drawings. Unless otherwise specified, the same symbols or symbols indicate the same members or parts or the same meanings. In addition, the "cross-sectional view" described directly or indirectly in this specification is based on a virtual cross section of a secondary battery cut along the "upper and lower directions" of the electrode assembly or electrode layer constituting the secondary battery. Similarly, the "thickness" direction described directly or indirectly in this specification is based on the "upper and lower directions" of the electrode material constituting the secondary battery. For example, in the case of a "secondary battery having a thickness like a plate" such as a button type or coin type, the "thickness" direction corresponds to the plate thickness direction of the secondary battery. The "planar view" used in this specification is based on a sketch when the object is viewed from above or below along the thickness direction. Unless otherwise specified, the same symbols or symbols indicate the same members or parts or the same meanings.

[0013] In this specification, the "upper surface" refers to the surface that is located at the top in the vertical direction among the surfaces that constitute the battery, and the "lower surface" refers to the surface that is located at the bottom in the vertical direction among the surfaces that constitute the battery. Assuming a typical secondary battery having two opposing main surfaces, the "upper surface" in this specification refers to one of the main surfaces, and the "lower surface" refers to the other of the main surfaces.

[0014] [Basic structure of secondary batteries] In this specification, the term "secondary battery" refers to a battery that can be repeatedly charged and discharged. Therefore, the secondary battery according to the present invention is not limited to the name, and may also include, for example, a power storage device.

[0015] The secondary battery according to the present invention comprises an electrode assembly including an electrode configuration layer including a positive electrode, a negative electrode, and a separator. An electrode assembly 10 is illustrated in FIG. 1(a) and FIG. 1(b). In FIG. 1(a), the electrode configuration layer 5 may have a planar laminated structure in which the electrode configuration layers 5 are laminated in a planar shape. In other words, the electrode assembly 10 may have a structure in which the electrode configuration layers 5 are laminated so as to be stacked on top of each other. On the other hand, in FIG. 1(b), the electrode configuration layer 5 may have a wound structure in which it is wound in a spiral shape. In other words, in FIG. 1(b), the electrode configuration layer 5 may have a wound structure in which a relatively long strip-like electrode configuration layer 5 including a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode is wound in a roll shape. In the secondary battery, such an electrode assembly is enclosed in an exterior body together with an electrolyte (e.g., a non-aqueous electrolyte). In addition, the structure of the electrode assembly is not necessarily limited to a planar laminated structure or a wound structure. For example, the electrode assembly may have a so-called stack-and-fold type structure in which a positive electrode, a separator, and a negative electrode are laminated on a long film and then folded.

[0016] The positive electrode 1 is composed of at least a positive electrode material layer and a positive electrode current collector. In the positive electrode, the positive electrode material layer is provided on at least one side of the positive electrode current collector, and the positive electrode material layer contains a positive electrode active material as an electrode active material. For example, each of the multiple positive electrodes in the electrode assembly may have a positive electrode material layer provided on both sides of the positive electrode current collector, or may have a positive electrode material layer provided only on one side of the positive electrode current collector.

[0017] The negative electrode 2 is composed of at least a negative electrode material layer and a negative electrode current collector. In the negative electrode, the negative electrode material layer is provided on at least one side of the negative electrode current collector, and the negative electrode material layer contains a negative electrode active material as an electrode active material. For example, each of the multiple negative electrodes in the electrode assembly may have a negative electrode material layer provided on both sides of the negative electrode current collector, or may have a negative electrode material layer provided only on one side of the negative electrode current collector.

[0018] The electrode active materials contained in the positive electrode 1 and the negative electrode 2, that is, the positive electrode active material and the negative electrode active material, are materials directly involved in the transfer of electrons in the secondary battery, and are the main materials of the positive and negative electrodes that are responsible for charging and discharging, that is, the battery reaction. More specifically, ions are brought to the electrolyte due to the "positive electrode active material contained in the positive electrode material layer" and the "negative electrode active material contained in the negative electrode material layer", and these ions move between the positive electrode and the negative electrode to transfer electrons and charge and discharge. The positive electrode material layer and the negative electrode material layer may be layers that can absorb and release lithium ions in particular. In other words, the secondary battery according to the present invention may be a non-aqueous electrolyte secondary battery in which lithium ions move between the positive electrode and the negative electrode via the non-aqueous electrolyte to charge and discharge the battery. When lithium ions are involved in charging and discharging, the secondary battery according to the present invention corresponds to a so-called "lithium ion battery", and the positive electrode and the negative electrode have layers that can absorb and release lithium ions.

[0019] The positive electrode active material of the positive electrode layer is, for example, composed of granules, and a binder may be included in the positive electrode layer to ensure sufficient contact between the particles and shape retention. Furthermore, a conductive assistant may be included in the positive electrode layer to facilitate the transfer of electrons that promote the battery reaction. Similarly, the negative electrode active material of the negative electrode layer is, for example, composed of granules, and a binder may be included in the positive electrode layer to ensure sufficient contact between the particles and shape retention, and a conductive assistant may be included in the negative electrode layer to facilitate the transfer of electrons that promote the battery reaction. In this way, since a plurality of components are contained, the positive electrode layer and the negative electrode layer can also be referred to as a "positive electrode mixture layer" and a "negative electrode mixture layer", respectively.

[0020] The positive electrode active material may be a material that contributes to the absorption and release of lithium ions. From this perspective, the positive electrode active material may be, for example, a lithium-containing composite oxide. More specifically, the positive electrode active material may be a lithium transition metal composite oxide containing lithium and at least one transition metal selected from the group consisting of cobalt, nickel, manganese, and iron. In other words, in the positive electrode material layer of the secondary battery according to the present invention, such a lithium transition metal composite oxide is preferably contained as the positive electrode active material. For example, the positive electrode active material may be lithium cobalt oxide, lithium nickel oxide, lithium manganate, lithium iron phosphate, or a material in which a part of the transition metal is replaced with another metal. Such a positive electrode active material may be contained as a single type, or may be contained in a combination of two or more types.

[0021] The binder that can be contained in the positive electrode layer is not particularly limited, but can include at least one selected from the group consisting of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, polytetrafluoroethylene, etc. The conductive assistant that can be contained in the positive electrode layer is not particularly limited, but can include at least one selected from carbon black such as thermal black, furnace black, channel black, ketjen black, and acetylene black, carbon fibers such as graphite, carbon nanotubes, and vapor-grown carbon fibers, metal powders such as copper, nickel, aluminum, and silver, and polyphenylene derivatives.

[0022] The thickness of the positive electrode layer is not particularly limited, but may be 1 μm or more and 300 μm or less, for example, 5 μm or more and 200 μm or less. The thickness of the positive electrode layer is the thickness inside the secondary battery, and may be the average value of measurements at any 10 points.

[0023] The negative electrode active material may be a material that contributes to the absorption and release of lithium ions. From this perspective, the negative electrode active material may be, for example, various carbon materials, oxides, and / or lithium alloys.

[0024] Examples of various carbon materials for the negative electrode active material include graphite (natural graphite, artificial graphite), hard carbon, soft carbon, diamond-like carbon, etc. In particular, graphite has high electronic conductivity and excellent adhesion to the negative electrode current collector. Examples of oxides for the negative electrode active material include at least one selected from the group consisting of silicon oxide, tin oxide, indium oxide, zinc oxide, and lithium oxide. The lithium alloy for the negative electrode active material may be a metal that can form an alloy with lithium, and may be, for example, a binary, ternary, or higher alloy of lithium and a metal such as Al, Si, Pb, Sn, In, Bi, Ag, Ba, Ca, Hg, Pd, Pt, Te, Zn, or La. Such oxides may have an amorphous structure. This is because deterioration caused by non-uniformity such as grain boundaries or defects is less likely to occur.

[0025] The binder that may be included in the negative electrode material layer is not particularly limited, but may be at least one selected from the group consisting of styrene butadiene rubber, polyacrylic acid, polyvinylidene fluoride, polyimide resin, and polyamideimide resin. For example, the binder included in the negative electrode material layer may be styrene butadiene rubber. The conductive assistant that may be included in the negative electrode material layer is not particularly limited, but may be at least one selected from carbon black such as thermal black, furnace black, channel black, ketjen black, and acetylene black, carbon fibers such as graphite, carbon nanotubes, and vapor-grown carbon fibers, metal powders such as copper, nickel, aluminum, and silver, and polyphenylene derivatives. The negative electrode material layer may contain a component resulting from a thickener component (e.g., carboxymethyl cellulose) used during battery production.

[0026] The thickness of the negative electrode layer is not particularly limited, but may be 1 μm or more and 300 μm or less, for example, 5 μm or more and 200 μm or less. The thickness of the negative electrode layer is the thickness inside the secondary battery, and may be the average value of measurements at any 10 points.

[0027] The positive electrode current collector and the negative electrode current collector used for the positive electrode and the negative electrode are members that contribute to collecting and supplying electrons generated in the electrode active material due to the battery reaction. Such an electrode current collector may be a sheet-shaped metal member. In addition, such an electrode current collector may have a porous or perforated form. For example, the current collector may be a metal foil, a punched metal, a net, an expanded metal, or the like. The positive electrode current collector used for the positive electrode is preferably made of a metal foil containing at least one selected from the group consisting of aluminum, stainless steel, nickel, and the like, and may be, for example, an aluminum foil. On the other hand, the negative electrode current collector used for the negative electrode is preferably made of a metal foil containing at least one selected from the group consisting of copper, stainless steel, nickel, and the like, and may be, for example, a copper foil. In this specification, "stainless steel" refers to stainless steel as defined in, for example, "JIS G 0203 Steel Terminology," and may be an alloy steel containing chromium or chromium and nickel.

[0028] The thickness of each of the positive electrode current collector and the negative electrode current collector is not particularly limited, but may be 1 μm or more and 100 μm or less, for example, 10 μm or more and 70 μm or less. The thickness of the positive electrode current collector and the negative electrode current collector is the thickness inside the secondary battery, and the average value of the measurements at any 10 points may be used.

[0029] The separator 3 used for the positive and negative electrodes is a member provided from the viewpoint of preventing short circuit due to contact between the positive and negative electrodes and maintaining electrolyte. In other words, the separator is a member that allows ions to pass while preventing electronic contact between the positive and negative electrodes. For example, the separator may be a porous or microporous insulating member, and may have a membrane form due to its small thickness. Although this is merely an example, a microporous membrane made of polyolefin may be used as the separator. In this regard, the microporous membrane used as the separator may contain, for example, only polyethylene (PE) or only polypropylene (PP) as polyolefin. Furthermore, the separator may be a laminate composed of a "microporous membrane made of PE" and a "microporous membrane made of PP". The surface of the separator may be covered with an inorganic particle coating layer and / or an adhesive layer, etc. The surface of the separator may have adhesive properties. In the present invention, the separator should not be limited to a particular name, and may be a solid electrolyte, a gel electrolyte, and / or insulating inorganic particles having similar functions.

[0030] The thickness of the separator is not particularly limited, but may be 1 μm or more and 100 μm or less, for example, 2 μm or more and 20 μm or less. The thickness of the separator is the thickness inside the secondary battery (particularly the thickness between the positive electrode and the negative electrode), and the average value of the measurements at any 10 points may be used.

[0031] In the secondary battery of the present invention, an electrode assembly 10 consisting of an electrode constituent layer 5 including a positive electrode 1, a negative electrode 2, and a separator 3 may be enclosed in an exterior body together with an electrolyte. The electrolyte can assist the movement of metal ions released from the electrodes (positive electrode and / or negative electrode). The electrolyte may be a "non-aqueous" electrolyte such as an organic electrolyte and an organic solvent, or may be an "aqueous" electrolyte containing water. When the positive electrode and the negative electrode have a layer capable of absorbing and releasing lithium ions, the electrolyte is preferably a "non-aqueous" electrolyte containing an organic electrolyte and / or an organic solvent. In other words, it is preferable that the electrolyte is a non-aqueous electrolyte. The electrolyte contains metal ions released from the electrodes (positive electrode and / or negative electrode), and therefore the electrolyte assists the movement of metal ions in the battery reaction. The electrolyte may be in the form of a liquid or gel.

[0032] The non-aqueous electrolyte is an electrolyte containing a solvent and a solute. A specific solvent for the non-aqueous electrolyte may contain at least a carbonate. Such a carbonate may be a cyclic carbonate and / or a chain carbonate. Although not particularly limited, the cyclic carbonate may be at least one selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC) and vinylene carbonate (VC). The chain carbonate may be at least one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC) and dipropyl carbonate (DPC). Although merely illustrative, a combination of a cyclic carbonate and a chain carbonate may be used as the non-aqueous electrolyte, for example, a mixture of ethylene carbonate and diethyl carbonate may be used. As a specific example of the solute of the non-aqueous electrolyte, a Li salt such as LiPF6 and / or LiBF4 may be used.

[0033] The exterior body 50 of the secondary battery is a member capable of housing or encasing the electrode assembly 10 including an electrode configuration layer 5 including a positive electrode 1, a negative electrode 2, and a separator 3. As will be described later, in the present invention, the exterior body 50 may be a metal exterior body having a non-laminated structure.

[0034] [Characteristics of the Secondary Battery of the Present Invention] The secondary battery 100 of the present invention comprises the above-mentioned electrode assembly 10, an exterior body 50 having an internal space for accommodating the electrode assembly 10, a terminal member 60 electrically connected to the electrode assembly 10, and a lead 40 electrically connecting the terminal member 60 and the electrode assembly 10 (see FIG. 2).

[0035] The electrode assembly 10 of this embodiment may have a wound structure as described in FIG. 1(b) above. That is, the electrode assembly 10 may have a wound structure formed by winding a plate-like structure including a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode into a roll. In the case of the wound electrode assembly 10, as shown in FIG. 2 and FIG. 3, leads may be drawn out from the upper surface and the lower surface of the electrode assembly 10. The upper surface lead 41 drawn out from the upper surface may be electrically connected to the positive electrode of the electrode assembly 10, and the lower surface lead 42 drawn out from the lower surface may be electrically connected to the negative electrode of the electrode assembly 10. The upper surface lead 41 and the lower surface lead 42 may be made of any material as long as they are conductive metals, and may be made of the same material as the positive electrode or the negative electrode or a different material as long as they can be electrically connected to the positive electrode or the negative electrode of the electrode assembly 10.

[0036] The exterior body 50 may be a metal exterior body having a non-laminated structure. In this case, the exterior body 50 is not a laminate member such as a metal sheet / adhesive layer / protective layer. In other words, it has a non-laminated structure. A metal exterior body having a non-laminated structure has a structure made of a single metal member. For example, such a metal exterior body may be a single member made of a metal such as stainless steel (SUS) and / or aluminum. In this case, the term "single metal member" means, in a broad sense, that the exterior body 50 does not have a so-called laminate structure, and in a narrow sense, that the exterior body 50 is a member made substantially only of metal. Therefore, if it is a member made substantially only of metal, the surface of the metal exterior body may be appropriately surface-treated.

[0037] From the viewpoint of easily storing the electrode assembly 10, the exterior body 50 may have a first exterior body 54 which is a lid-shaped member and a second exterior body 56 which is a cup-shaped member, as in the preferred embodiment shown in FIG. 2. The first exterior body 54 and the second exterior body 56 may be joined by welding. In this specification, the "cup-shaped member" means a member having a side portion corresponding to a body portion and a main surface portion (for example, a bottom portion in a typical embodiment) continuous therewith, and a hollow portion is formed inside. In this specification, the "lid-shaped member" means a member provided to cover such a cup-shaped member. The lid-shaped member may be, for example, a single member (typically a plate-shaped member) extending in the same plane. In the exterior body, the lid-shaped member and the cup-shaped member may be combined so that the outer edge portion of the lid-shaped member and the upper end portion of the side portion of the cup-shaped member are aligned with each other.

[0038] The first exterior body 54, which is a lid-like member, may have an opening 54a formed in the center. A terminal member 60 may be provided to cover the opening 54a. An insulating material 70 may be disposed between the terminal member 60 and the first exterior body 54.

[0039] The insulating material 70 is provided so as to fill the gap between the first exterior body 54 and the terminal member 60, and can be understood as contributing to "sealing". As shown in FIG. 2, the insulating material 70 may be shaped to conform to the first exterior body 54 so as to extend to the area outside the terminal member 60. In other words, the insulating material 70 may be provided on the exterior body 50 so as to protrude from the terminal member 60 to the outside. There is no particular limit to the type of the insulating material 70 as long as it exhibits "insulating properties". It is preferable that the insulating material has not only "insulating properties" but also "adhesive properties". For example, the insulating material 70 may be made of a thermoplastic resin. Although this is merely one specific example, the insulating material may be made of a polyolefin such as polyethylene and / or polypropylene.

[0040] The terminal member 60 means an output terminal in the secondary battery that is used for connecting to an external device. The terminal member 60 may have, for example, a flat plate shape. The flat terminal member 60 may be, for example, a metal plate. The material of the terminal member 60 is not particularly limited, and may include at least one metal selected from the group consisting of aluminum, nickel, and copper. As can be seen from the preferred embodiment shown in FIG. 2, the terminal member 60 may have a shape that conforms to the first exterior body 54. That is, in a cross-sectional view as shown in the figure, the terminal member 60, the surface of the first exterior body 54 on which it is provided, and the insulating material 70 may have a parallel arrangement relationship with each other. The planar shape of the terminal member 60 is also not particularly limited, and may be, for example, a circle or a rectangle including a square. The terminal member 60 may be electrically connected to the upper surface lead 41 drawn from the upper surface of the electrode assembly 10 through the opening 54a of the first exterior body 54. In other words, the terminal member 60 is electrically connected to the top lead 41 that is conductive with the positive electrode, and may therefore function as the positive electrode of the secondary battery. The electrical connection between the top lead 41 and the first exterior body 54 may be performed by, for example, laser welding.

[0041] The second exterior body 56, which is a cup-shaped member, has a storage space for storing the electrode assembly 10, and the above-mentioned electrode assembly 10 may be stored in the storage space. In the preferred embodiment shown in Fig. 2, the second exterior body 56 may be electrically connected to the bottom lead 42 drawn out from the bottom surface of the electrode assembly 10. In other words, the second exterior body 56 may function as the negative electrode of the secondary battery because it is electrically connected to the bottom lead 42 which is conductive with the negative electrode. The electrical connection between the bottom lead 42 and the second exterior body 56 and the connection between the first exterior body 54 and the second exterior body 56 may be performed by, for example, laser welding.

[0042] The lead 40 drawn out from the electrode assembly 10 is fixed to the inner surface of the exterior body 50. Here, the "inner surface of the exterior body" in this specification means the surface of the exterior body that is not exposed to the outside in the completed secondary battery. Also, "fixed" in this specification means that the lead is attached so as not to move with respect to a predetermined position of the exterior body. For example, in a preferred embodiment shown in FIG. 2, the upper surface lead 41 drawn out from the electrode assembly 10 may be fixed to the inner surface of the first exterior body 54. According to this configuration, compared with a conventionally known "secondary battery having a lead connected only to an external electrode", since the upper surface lead 41 is fixed to the first exterior body 54, the load applied to the upper surface lead 41 can be distributed to the first exterior body 54 as well. In particular, in the case of the wound-type electrode assembly shown in FIG. 1(b) or FIG. 2, when a load is applied to the lead and / or the electrode assembly, a winding shift occurs, which may cause a short circuit between the positive electrode and the negative electrode, so that it is useful to distribute the load to the first exterior body 54.

[0043] Furthermore, since the upper surface lead 41 is fixed to the terminal member 60 in addition to the first outer casing 54, the fixing strength can be increased compared to a conventionally known "secondary battery having a lead connected only to an external electrode."

[0044] In addition, in a conventionally known "secondary battery having a lead connected only to an external electrode," when the lead is stored inside the exterior body, if the lead is long, the number of times it needs to be folded increases, making the handling of the lead complicated. On the other hand, in a preferred embodiment of the present invention (see FIG. 2), the top surface lead 41 drawn out from the electrode assembly 10 is stored in a state where it is fixed to the inner surface of the first exterior body 54. In other words, the top surface lead 41 can be stored in the exterior body in a state where it is shortened by the amount of the top surface lead 41 fixed to the first exterior body 54. In addition, by positioning the top surface lead 41 at a position inside the first exterior body 54 that does not interfere with the storage of the top surface lead 41 and fixing it, the lead can be easily handled when the lead is stored. Note that the length of the lead is preferably relatively short within a range that allows handling. By shortening the lead, it is possible to make it compact when stored.

[0045] Furthermore, in a conventional "secondary battery having leads connected only to external electrodes," if the internal pressure of the exterior body rises abnormally and the exterior body breaks, there is a risk that the external electrodes will come off the leads and scatter into the surroundings. On the other hand, in a preferred embodiment of the present invention (see Figs. 2 and 4), the top lead 41 is fixed to the terminal member 60 in addition to the first exterior body 54. Therefore, since the fixing strength is increased compared to a conventional "secondary battery having leads connected only to external electrodes," it is possible to reduce the likelihood of the first exterior body 54 and the terminal member 60 coming off the leads and scattering into the surroundings even if the internal pressure of the exterior body rises abnormally.

[0046] The leads may be fixed by a fixing member. In the preferred embodiment shown in Fig. 2, the top surface lead 41 is preferably fixed by a fixing member 80. That is, in this embodiment, it is preferable that the fixing is not performed by crimping or welding that does not use a fixing member. Fixation using such a fixing member 80 can firmly fix the top surface lead 41 and the first exterior body 54.

[0047] The fixing member 80 used to fix the lead is preferably a member that provides adhesion between the exterior body and the lead. In this specification, "adhesiveness" means a property that does not easily peel off after adhesion. Examples of such fixing members 80 include adhesives containing polyethylene and / or polypropylene, olefin-based adhesives, resin-based adhesives, hot melt adhesives, etc. Fixing methods using such fixing members 80 can achieve stronger fixation than fixation by crimping, welding, etc.

[0048] The fixing strength between the upper surface lead 41 and the first exterior body 54 may be higher than the connection strength between the terminal member 60 and the upper surface lead 41. In other words, the fixing strength between the terminal member 60 and the first exterior body 54 fixed using the fixing member 80 may be higher than the connection strength between the upper surface lead 41 and the fixing member 80 electrically connected by the above-mentioned laser welding or the like. Here, in this specification, the "connection strength" means an index indicating how strong it is to peel off when the members are connected to each other. With this fixing, even if the internal pressure of the exterior body abnormally increases, the first exterior body 54 and the upper surface lead 41 are firmly fixed, so that it is possible to reduce the first exterior body 54 and the terminal member 60 coming off the lead and scattering around.

[0049] Furthermore, the fixing member 80 is preferably an insulating member. In this specification, "insulating" refers to a property that makes it difficult for an electric current to flow, and has a resistivity of 10 6 It means a range of Ω·m or more. In the preferred embodiment shown in FIG. 2, the upper surface lead 41 and the first exterior body 54 are electrically insulated by the fixing member 80. As a more preferred method of electrically insulating the upper surface lead 41 and the first exterior body 54, an insulating material may be provided on a part or the entire area of ​​the inner surface of the first exterior body 54. In this way, if the fixing member 80 is an insulating member, the insulation between the positive electrode and the negative electrode is maintained even if the upper surface lead 41 is fixed to the first exterior body 54. In the preferred embodiment shown in FIG. 2, in a case where the first exterior body 54 and the second exterior body 56 are already electrically insulated from each other, the fixing member 80 does not need to be an insulating member.

[0050] Next, additional aspects of lead fixation will be described.

[0051] The leads may be folded and stored in the exterior body. That is, in the preferred embodiment shown in Fig. 2, the top lead 41 may be folded and stored in the storage space between the first exterior body 54 and the second exterior body 56. That is, the top lead 41 may be a flexible conductive member. By folding and storing the top lead 41, a secondary battery that is small in thickness can be obtained.

[0052] 2, the fixing position of the top lead 41 is preferably between the connection position of the top lead 41 with the electrode assembly 10 and the connection position of the top lead 41 with the terminal member 60. In other words, it is preferable that the top lead 41 is fixed to the first exterior body 54 in an intermediate region of the top lead 41. With this fixing mode, the top lead 41 can be stored in the exterior body in a fixed state shortened by the length from the connection position with the terminal member 60 to the fixed position with the first exterior body 54.

[0053] 2, the first exterior body 54 and the second exterior body 56 are welded to each other at a weld 59, and it is preferable that the length A from the fixed position of the top lead 41 and the first exterior body 54 to the weld 59 is longer than the horizontal length B between the fixed position of the top lead 41 and the first exterior body 54 and an end portion of the opening 54a of the first exterior body 54. By fixing the top lead 41 and the first exterior body 54 at such a position with a fixing member 80, the effect of heat generated when the first exterior body 54 and the second exterior body 56 are welded to the fixing member 80 can be reduced.

[0054] 2, the top lead 41 may be fixed to the inner surface of the first exterior body 54 arranged inside the terminal member 60. In other words, the top lead 41 may be fixed to the back surface of the member constituting the secondary battery that is not exposed to the outside. By fixing the top lead 41 at such a position, the top lead 41 can be stored in the storage space between the first exterior body 54 and the second exterior body 56.

[0055] 2, the top surface lead 41 may be fixed to the inner surface of the first exterior body 54 through an opening 54a of the first exterior body 54. By employing such a fixing method, it is possible to appropriately establish electrical continuity between the top surface lead 41 and the terminal member 60.

[0056] 2, the top lead 41 and the first exterior body 54 are fixed at one location, but this is not limiting and the fixing locations may be multiple. By fixing the top lead 41 at multiple locations in this manner, the fixing strength can be increased.

[0057] 2, the top surface lead 41 is fixed to the first exterior body 54, but is not limited to this example and may be fixed to the second exterior body 56. Fixing the top surface lead 41 to such a position can also reduce the load applied to the lead.

[0058] In this embodiment, the overall shape of the secondary battery in plan view is approximately circular. That is, the secondary battery 100 has a button or coin shape in terms of its external shape (see FIG. 5(a)). However, the present invention is not necessarily limited to this. For example, the secondary battery may be a square-shaped battery (see FIG. 5(b)). That is, the shape of the secondary battery 100 in plan view is not limited to a circle, and may be a square or rectangular shape.

[0059] Next, another embodiment of the present invention will be described with reference to Fig. 6. Fig. 6 is a cross-sectional view showing a schematic configuration of a secondary battery according to another embodiment of the present invention. Note that the description of the same configuration as the above-mentioned embodiment will be omitted.

[0060] The electrode assembly 10 of this embodiment may have a laminated structure as described above in FIG. 1(a). That is, the electrode assembly 10 may have a laminated structure in which plate-like structures including a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode are stacked. In this case, leads may be drawn out from both side surfaces of the electrode assembly 10, and in the preferred embodiment shown in FIG. 6, an upper surface lead 41 drawn out from the right side surface toward the upper surface and a lower surface lead 42 drawn out from the left side surface toward the lower surface may be provided. The upper surface lead 41 may be electrically connected to the positive electrode of the electrode assembly 10, and the lower surface lead 42 may be electrically connected to the negative electrode of the electrode assembly 10.

[0061] In the preferred embodiment shown in FIG. 6, the top lead 41 may be fixed to the first exterior body 54. When the top lead 41 is fixed to the first exterior body 54 in this manner, the load applied to the top lead 41 can be distributed to the first exterior body 54 as well. Furthermore, the top lead 41 is fixed to the terminal member 60 in addition to the first exterior body 54, so that the fixing strength can be increased. Furthermore, the top lead 41 can be stored in the exterior body in a state where it is shortened by the amount of the top lead 41 fixed to the first exterior body 54. Furthermore, by positioning the top lead 41 at an inner position of the first exterior body 54 that does not interfere with the storage of the top lead 41 and fixing it, the lead can be easily handled when the lead is stored. Furthermore, even if the internal pressure of the exterior body increases abnormally, it is possible to reduce the first exterior body 54 and the terminal member 60 coming off the lead and scattering around.

[0062] Next, another embodiment of the present invention will be described with reference to Fig. 7. Fig. 7 is a cross-sectional view showing a schematic configuration of a secondary battery according to another embodiment of the present invention. Note that the description of the same configuration as the above-mentioned embodiment will be omitted.

[0063] In a preferred embodiment shown in Fig. 7, the exterior body 50 may have a first exterior body 54 and a third exterior body 58 which are lid-like members, and a second exterior body 56 which is a cylindrical member. The first exterior body 54 may seal the upper surface of the second exterior body 56, and the third exterior body 58 may seal the lower surface of the second exterior body 56. From the viewpoint of manufacturing costs, the first exterior body 54 and the third exterior body 58 may have the same shape or different shapes. The first exterior body 54 and the third exterior body 58 may be welded to the second exterior body 56 by laser welding.

[0064] In a preferred embodiment shown in FIG. 7, the upper surface lead 41 drawn out from the electrode assembly 10 may be fixed to the inner surface of the first exterior body 54 by a fixing member 80. Furthermore, the lower surface lead 42 drawn out from the electrode assembly 10 may be fixed to the inner surface of the third exterior body 58 by a fixing member 80. According to such an embodiment, since the lower surface lead 42 is also fixed to the third exterior body 58 in addition to the upper surface lead 41 described in the above embodiment, the load applied to the lower surface lead 42 can be distributed to the third exterior body 58 as well. Furthermore, since the lower surface lead 42 is fixed to the terminal member 60 in addition to the third exterior body 58, the fixing strength can be increased. Furthermore, the lower surface lead 42 can be stored in the exterior body in a state where it is shortened by the amount fixed to the third exterior body 58. Furthermore, by fixing the lower surface lead 42 at a position inside the third exterior body 58 that does not interfere with the storage of the lower surface lead 42, the lead can be easily handled when the lead is stored. Furthermore, even if the internal pressure of the exterior body increases abnormally, it is possible to reduce the likelihood that third exterior body 58 and terminal members 60 will come off the leads and fly off into the surrounding area.

[0065] [Features of the method for producing a secondary battery according to the present invention] Next, a method for manufacturing a secondary battery of the present invention will be described with reference to Figs. 8 to 11. Figs. 8 to 11 are cross-sectional views showing steps for manufacturing a secondary battery of the present invention. Note that the method described below is merely an example, and the method for manufacturing a secondary battery according to an embodiment of the present invention is not limited to the following method.

[0066] First, the electrode assembly 10 is manufactured by stacking or winding electrode constituent layers including a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, and drawing out the leads electrically connected to the positive electrode and the negative electrode, respectively. In this embodiment, the upper lead 41 may be drawn to the upper surface side of the electrode assembly, and the lower lead 42 may be drawn to the lower surface side. Then, the electrolyte is stored in the second exterior body 56, which is a cup-shaped member, together with the manufactured electrode assembly 10 (see FIG. 8). At this time, the lower lead 42 of the electrode assembly 10 and the second exterior body 56 may be electrically connected by laser welding. Note that the electrical connection between the lower lead 42 and the second exterior body 56 is not limited to laser welding, and may be made using, for example, a conductive adhesive. In this way, the electrode assembly 10 is stored in the second exterior body.

[0067] Next, a sealing structure that seals the upper surface of the second exterior body 56 is produced. The sealing structure used in this embodiment may include a first exterior body 54 having an opening 54a, a terminal member 60 that covers the opening 54a and acts as an external terminal, and an insulating material 70 that has insulating and adhesive properties and is provided so as to fill the gap between the terminal member 60 and the first exterior body 54. In other words, the terminal member 60 may be adhered to the first exterior body 54 by the insulating material 70 that has adhesive properties. In this manner, a sealing structure that seals the upper surface of the second exterior body 56 is produced.

[0068] Next, the lead electrically connected to the electrode assembly is electrically connected to the terminal member. In the preferred embodiment shown in FIG. 9, the upper surface lead 41 drawn out from the upper surface of the electrode assembly 10 may be electrically connected to the terminal member 60 through the opening 54a of the first exterior body 54. This electrical connection may be performed by, for example, laser welding. Note that the electrical connection is not limited to laser welding, and may be performed using, for example, a conductive adhesive. In this manner, the electrode assembly 10 and the terminal member 60 are electrically connected via the lead.

[0069] Next, the lead is fixed to the inner surface of the exterior body. In the preferred embodiment shown in FIG. 10, the upper surface lead 41 may be fixed to the inner surface of the first exterior body 54. A fixing member 80 having insulating and adhesive properties may be used to fix the upper surface lead 41 to the first exterior body 54. By fixing the upper surface lead 41 to the first exterior body 54 using the fixing member 80, the upper surface lead 41 is firmly fixed to the first exterior body 54 and the upper surface lead 41 and the first exterior body 54 are electrically insulated from each other. Note that, in the present embodiment, a mode in which the upper surface lead 41 is fixed to the inner surface of the first exterior body 54 has been described, but the present invention is not limited to this example, and the upper surface lead 41 may be fixed to the inner surface of the second exterior body 56, for example.

[0070] In addition, the position at which the fixing member 80 is provided is preferably close to the opening 54a of the first exterior body 54. That is, as shown in Fig. 2, it is preferable that the length A from the fixing position of the top surface lead 41 and the first exterior body 54 to the welded portion 59 is longer than the horizontal length B between the fixing position of the top surface lead 41 and the first exterior body 54 and an end portion of the opening 54a of the first exterior body 54. By providing the fixing member 80 at such a position, even if laser welding is performed between the first exterior body 54 and the second exterior body 56 described below, the effect on the fixing member 80 can be reduced because the fixing member 80 is disposed at a position away from the welded portion 59.

[0071] Furthermore, the strength of the connection between the terminal member 60 and the first exterior body 54 fixed using the fixing member 80 may be stronger than the connection strength between the upper surface lead 41 electrically connected by the above-mentioned laser welding or the like and the fixing member 80. With this type of fixation, even if the internal pressure of the exterior body increases abnormally, the first exterior body 54 and the upper surface lead 41 are firmly fixed together, so that it is possible to reduce the possibility of the first exterior body 54 and the terminal member 60 coming off the lead and scattering into the surroundings.

[0072] Next, as shown in FIG. 11, the top surface lead 41 is folded and stored in the second exterior body 56. Here, when the top surface lead 41 is folded and stored, since the top surface lead 41 is fixed to the first exterior body 54, the load applied to the top surface lead 41 can be distributed to the first exterior body 54 as well, and the load can be reduced. Furthermore, since the lead 40 is fixed to the terminal member 60 in addition to the first exterior body 54, the fixing strength can be increased. Furthermore, the top surface lead 41 can be stored in the exterior body in a state where it is shortened by the amount fixed to the first exterior body 54. Furthermore, by positioning the top surface lead 41 at an inner position of the first exterior body 54 that does not interfere with the storage of the top surface lead 41 and fixing it, the lead can be easily handled when the lead is stored.

[0073] Then, the first exterior body 54 is placed on the upper surface of the second exterior body 56, and the first exterior body 54 and the second exterior body 56 are attached to each other. This attachment may be performed by laser welding, for example. Note that the method of attaching the first exterior body 54 and the second exterior body 56 is not limited to laser welding, and may be, for example, using an adhesive. A conductive adhesive may be used to electrically connect the first exterior body 54 and the second exterior body 56. Furthermore, an insulating adhesive may be used to electrically insulate the first exterior body 54 and the second exterior body 56 from each other.

[0074] As described above, the method for manufacturing a secondary battery according to the present invention includes a connecting step of electrically connecting the lead electrically connected to the electrode assembly to the terminal member, and a fixing step of fixing the lead to the inner surface of the exterior body. According to the secondary battery manufactured by this embodiment, since the lead is fixed to the exterior body, the load applied to the lead can be distributed to the exterior body as well, and the load can be reduced. Since the lead is fixed to the terminal member in addition to the exterior body, the fixing strength can be increased. Furthermore, the lead can be stored in the exterior body in a state where it is shortened by the amount fixed to the exterior body, and the storage can be simplified. Furthermore, by positioning the lead at an inner position of the exterior body that does not interfere with the storage of the lead and fixing it, the handling of the lead when storing the lead can be made easy. Furthermore, even if the internal pressure of the exterior body increases abnormally, the exterior body and the terminal member can be reduced from coming off the lead and scattering around.

[0075] It should be noted that the embodiments disclosed herein are illustrative in all respects and are not intended to be limiting. Therefore, the technical scope of the present invention is not interpreted solely by the above-described embodiments, but is defined by the claims. The technical scope of the present invention includes all modifications within the scope and meaning equivalent to the claims. [Industrial Applicability]

[0076] The secondary battery according to the present invention can be used in various fields in which the use of batteries or the storage of electricity is anticipated. Although merely illustrative, the secondary battery of the present invention can also be used in the electrical, information and communication fields in which mobile devices and the like are used (for example, mobile phones, smartphones, notebook computers and digital cameras, activity meters, arm computers, electronic paper, wearable devices, or small electronic devices such as RFID tags, card-type electronic money, and smart watches, or the mobile device field), household and small industrial applications (for example, power tools, golf carts, household, nursing care and industrial robots), large industrial applications (for example, forklifts, elevators, and port cranes), transportation systems (for example, hybrid cars, electric cars, buses, trains, electrically assisted bicycles, and electric two-wheelers), power system applications (for example, various power generation, road conditioners, smart grids, and general household installation type power storage systems), as well as medical applications (medical devices such as earphones and hearing aids), pharmaceutical applications (medical management systems, etc.), IoT, and space and deep sea applications (for example, space probes, submersible research vessels, etc.). [Explanation of symbols]

[0077] 1 positive electrode 2 negative electrode 3. Separator 5 Electrode composition layer 10 Electrode assembly 40 Lead 41 Top lead 42 Bottom lead 50 Exterior body 54 First Exterior Body 54a opening 56 Second Exterior Body 58 Third Exterior Body 59 Welded parts 60 Terminal material 70 Insulation Materials 80 Fixing member 100 Secondary battery

Claims

1. A secondary battery comprising: an electrode assembly; an exterior body having an internal space for accommodating the electrode assembly; a terminal member electrically connected to the electrode assembly; and a lead electrically connecting the terminal member and the electrode assembly, The exterior body includes a first exterior body that is a lid-like member and a second exterior body, The lead is flexible and is fixed to the inner surface of the first exterior body in a folded state by a fixing member.

2. The secondary battery according to claim 1 , wherein the fixing member is a member that provides adhesion between the first exterior body and the lead.

3. The secondary battery according to claim 1 , wherein the fixing member is an insulating member.

4. The secondary battery according to any one of claims 1 to 3, wherein the fixing position is the inner surface of the first exterior body arranged inside the terminal member.

5. 5. The secondary battery according to claim 1, wherein the fixing position is located between a connection position of the lead to the electrode assembly and a connection position of the lead to the terminal member.

6. 6. The secondary battery according to claim 1, wherein the leads are folded and housed in the exterior body.

7. The secondary battery according to any one of claims 1 to 6, wherein the fixing position is a plurality of positions.

8. 8. The secondary battery according to claim 1, wherein a fixing strength between the lead and the first exterior body is higher than a connection strength between the terminal member and the lead.

9. the exterior body includes a first exterior body that is a lid-like member for an upper surface, a second exterior body that is a cylindrical member, and a third exterior body that is a lid-like member for a lower surface, 9. The secondary battery according to claim 1, wherein the lead is fixed to at least an inner surface of the first exterior housing and an inner surface of the third exterior housing.

10. The first exterior body has an opening, The secondary battery according to any one of claims 1 to 8, wherein a lead electrically connected to the terminal member passes through the opening and is fixed to an inner surface of the first exterior body.

11. The first exterior body and the second exterior body have a welded portion welded to each other, The secondary battery according to any one of claims 1 to 10, wherein the horizontal length between the welded portion and the fixed position is longer than the horizontal length between the fixed position and the edge of the opening of the first exterior body.

12. The secondary battery according to any one of claims 1 to 11, wherein the electrodes of the electrode assembly include a positive electrode and a negative electrode capable of absorbing and releasing lithium ions.

13. A method for manufacturing a secondary battery comprising: an electrode assembly; an exterior body having an internal space for accommodating the electrode assembly; a terminal member electrically connected to the electrode assembly; and a flexible lead electrically connecting the terminal member and the electrode assembly, the exterior body comprising a first exterior body which is a lid-shaped member, and a second exterior body, the lead being fixed to an inner surface of the first exterior body by a fixing member in a bent state, a connecting step of electrically connecting the lead, which is electrically connected to the electrode assembly, to the terminal member; and a fixing step of fixing the lead to the inner surface of the first exterior body with a fixing member.

14. The method for producing a secondary battery according to claim 13 , wherein the fixing step uses a technique that provides a higher fixing strength than the connecting step.

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