JP7651314B2 - Nonaqueous electrolyte secondary battery and method for manufacturing the same - Google Patents

Description

The present invention relates to a non-aqueous electrolyte secondary battery and a method for manufacturing a non-aqueous electrolyte secondary battery.

So-called coin-shaped non-aqueous electrolyte secondary batteries, which are made by housing an electrode structure serving as a power generating element in a flat cylindrical metallic exterior body, can be used as a power source for small devices such as wearable devices and hearing aids. For use in small devices, batteries are required to have a large battery capacity and a large charge/discharge current. In order to meet these required characteristics and increase the area of the electrodes facing each other in the battery, a battery structure is known in which a pair of strip-shaped electrodes are wound facing each other with a strip-shaped separator interposed therebetween to form an electrode structure, and the electrode structure is then housed in the exterior body.

In this battery structure, the exposed portion of the current collector constituting the electrode, or a connection member such as a lead tab integrated with the current collector, is connected to the exterior body, thereby electrically connecting the electrode and the exterior body, and the exterior body functions as an external terminal of the battery. A welding technique such as ultrasonic welding or resistance welding is used to connect the current collector (or lead tab) integrated with the electrode to the exterior body.
When welding, welding may become difficult due to a decrease in strength caused by thinning of the current collector, poor welding caused by embrittlement due to heat during welding, or the presence of foreign matter such as active material between the current collector and the welding contact (ultrasonic horn in ultrasonic welding, welding electrode in resistance welding). To solve such welding problems, a conductive connection using a conductive adhesive has been proposed (see, for example, Patent Document 1).

JP 2002-289260 A

When using the above-mentioned conductive adhesive, the lead tab and the exterior body are bonded via a paste-like adhesive, and then the conductive adhesive is dried or otherwise cured to fix the two together. In this case, the connection between the lead tab and the exterior body remains weak until the conductive adhesive is completely cured. In the connection between the electrode structure in which the electrode and the lead tab are integrated and the negative electrode can or positive electrode can, which is a component of the exterior body, if the connection is weak until the conductive adhesive is completely cured, many components cannot be moved during handling such as assembly, reducing the degree of freedom of movement during work.
Even if the electrode structure is connected to either the negative or positive can in advance and the conductive adhesive is cured, the connection between the electrode structure and one can itself is bulky and interferes with the connection to the other can, which increases the restrictions on movement during the work and reduces the work speed.

In addition, if a conductive adhesive is applied to the inside of the can in advance, cured, and then the electrode structure is sealed inside the can, the contact state between the lead tab and the can changes according to the expansion and contraction of the wound electrode during charging and discharging, making it impossible to maintain a stable conductive connection at all times, which can cause variations in electrical characteristics.

In view of the above problems, the present invention aims to provide a non-aqueous electrolyte secondary battery that maintains a stable conductive connection and suppresses variation in electrical characteristics, and a method for manufacturing a non-aqueous electrolyte secondary battery.

The nonaqueous electrolyte secondary battery of the present invention comprises an exterior body in which a first container and a second container are insulated and sealed, and an electrode structure including a first electrode and a second electrode housed in the exterior body and electrically connected to the first container and the second container, respectively, at least one of the first electrode and the second electrode further comprises a lead tab electrically connected to the electrode, an uneven portion having protrusions which is a solidified conductive paste is formed on an inner surface of at least one of the first container and the second container , and the uneven portion and the lead tab are solid-state bonded by pressure welding.

According to the present invention, the lead tab and the can of the non-aqueous electrolyte secondary battery are electrically connected by a solid-state bonding using a pressure connection via a concave-convex portion having convex portions that are solidified conductive paste formed on the inner surface of the can of the non-aqueous electrolyte secondary battery. This conductive connection can suppress changes in the connection state due to internal changes such as expansion and contraction of the electrodes due to charging and discharging. Therefore, a non-aqueous electrolyte secondary battery can be obtained that maintains a stable conductive connection and suppresses variations in electrical characteristics.

The nonaqueous electrolyte secondary battery of the present invention is characterized in that the uneven portion has a convex portion having a sharp tip.

According to the present invention, when the convex portion has a shape with a sharp tip, the convex portion can easily penetrate the lead tab. This exposes a new interface of the lead tab, reducing the contact resistance between the lead tab and the container.

The nonaqueous electrolyte secondary battery of the present invention is characterized in that the uneven portion has a convex portion having a smooth surface at its tip.

According to the present invention, when the convex portion has a shape with a smooth surface at the tip, for example, flat, it is possible to suppress unevenness of the lead tab, thereby preventing deformation of the electrode structure. This makes it possible to prevent internal short circuits in the battery.

In the nonaqueous electrolyte secondary battery of the present invention, the lead tabs are arranged in a multiple layer in a planar position between the uneven portion and the electrode structure.

According to the present invention, the lead tab is structured so that two or more layers are laminated between the uneven portion formed on the inner surface of the can and the electrode structure. This makes it possible to prevent internal short circuits in the battery by absorbing the unevenness in the laminated structure.

The method for producing a nonaqueous electrolyte secondary battery according to the present invention is a method for producing a nonaqueous electrolyte secondary battery comprising: an exterior body in which a first container and a second container are insulated and sealed; and an electrode structure including a first electrode and a second electrode housed in the exterior body and electrically connected to the first container and the second container, respectively; at least one of the first electrode and the second electrode further comprises a lead tab electrically connected to the electrode; and a protrusion, which is a solidified body of a conductive paste, is fixed to an inner surface of at least one of the first container and the second container to form a protrusion and recess , and the protrusion and recess are pressure-welded to connect the lead tab.

According to the present invention, the conductive connection of the nonaqueous electrolyte secondary battery is performed by pressure-welding using the uneven portion formed on the inner surface of the can by fixing the protrusions, which are solidified conductive paste, so that the insulating sealing of the exterior body and the conductive connection can be performed simultaneously. This increases the connection strength between the can and the lead tab. In addition, the degree of freedom of operation when performing work associated with the conductive connection is improved by reducing restrictions on operation during handling, such as interference between components when sequentially connecting the first and second containers and the electrode structure. Furthermore, the number of work steps can be reduced, allowing efficient assembly work.

According to the present invention, the can and the lead tab are pressure-welded and connected via the unevenness formed on the inner surface of the can, so that the lead tab deforms to conform to the unevenness and the contact area between the lead tab and the can is increased, thereby providing a nonaqueous electrolyte secondary battery having a stable conductive connection that is less susceptible to changes in the shape of the electrode structure due to charging/discharging, etc.
Furthermore, according to the present invention, a method for manufacturing a nonaqueous electrolyte secondary battery can be provided that provides good workability during manufacturing by connecting the can and the lead tab by pressure welding when sealing.

1 is a schematic cross-sectional view illustrating a nonaqueous electrolyte secondary battery according to an embodiment of the present invention in a state before components are insulated and sealed. 1 is a schematic cross-sectional view illustrating a nonaqueous electrolyte secondary battery according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view illustrating an uneven portion in an exterior body of the nonaqueous electrolyte secondary battery according to the embodiment of the present invention. FIG. 4 is a schematic cross-sectional view illustrating a state before components of a nonaqueous electrolyte secondary battery in which lead tabs according to another embodiment of the present invention are formed into a laminated structure are sealed insulated.

Below, an example of a nonaqueous electrolyte secondary battery according to an embodiment of the present invention will be given, and its configuration will be described in detail with reference to Figures 1 to 4. Note that in the drawings used in the following description, the scale of each component has been appropriately changed so that each component is of a recognizable size.

The nonaqueous electrolyte secondary battery 1 of this embodiment is a so-called coin (button) type battery. As shown in Fig. 1, the nonaqueous electrolyte secondary battery 1 includes a thin (flat) exterior body 10 and an electrode structure 30 housed in the exterior body 10.
The exterior body 10 includes a cylindrical second container (positive electrode can 12) made of metal with a bottom, a cylindrical first container (negative electrode can 11) made of metal with a lid (hat-shaped) that closes the opening of the positive electrode can 12, and a gasket 13 provided along the inner circumferential surface of the positive electrode can 12. The electrode structure 30 includes a first electrode (negative electrode body 31), a second electrode (positive electrode body 32), and a separator 33.

As shown in FIG. 2, the exterior body 10 is formed by insulating the positive electrode can 12 with a gasket 13 placed on the outside of the negative electrode can 11. Inside the exterior body 10, a storage space is formed surrounded by the positive electrode can 12 and the negative electrode can 11. The electrode structure 30 is stored in this storage space, which is further filled with an electrolyte (not shown) described below.

Such a coin (button) type non-aqueous electrolyte secondary battery 1 has an outer diameter of φ3 to 20 mm and is formed in a flattened cylindrical shape with a height of about 1 to 5 mm. This embodiment is not limited to such coin (button) type batteries, but can also be applied to batteries with various metal cases such as thin and rectangular, so long as the connection between the electrodes and the container is as shown below. One example of the battery size is the 920 size (outer diameter φ9.5 mm x height 2.0 mm), which is a common size for coin type non-aqueous electrolyte secondary batteries.

As described above, the negative electrode can 11 constituting the exterior body 10 is configured in a covered cylindrical shape (hat shape) and configured so that its tip portion enters the positive electrode can 12 from the opening. Examples of the material for such a negative electrode can 11 include conventionally known stainless steels, such as SUS316L, SUS329JL, or SUS304-BA. Also, the negative electrode can 22 can be made of, for example, a clad material formed by pressing copper, nickel, or the like onto stainless steel.
Although the tip of the negative electrode can 11 has a folded shape, the present invention is not limited to this. For example, the tip may be an end face of a metal plate material, which does not have a folded shape.

As described above, the positive electrode can 12 is configured as a bottomed cylinder with a circular opening in a plan view. As with the material of the negative electrode can 11, the material of the positive electrode can 12 can be any conventionally known material without any restrictions, such as SUS316L, SUS329JL, or stainless steel such as NAS64.

As shown in FIG. 2, the negative electrode can 11 and the positive electrode can 12 are fixed together by crimping the periphery of the opening of the positive electrode can 12 to the negative electrode can 11 with a gasket 13 between them, and the nonaqueous electrolyte secondary battery 1 is sealed with a storage space formed. For this reason, the maximum inner diameter of the positive electrode can 12 is larger than the maximum outer diameter of the negative electrode can 11.

The thickness of the metal plate material used for the negative electrode can 11 and the positive electrode can 12 is generally about 0.1 to 0.3 mm, and for example, the average thickness of the entire positive electrode can 12 and the negative electrode can 22 can be configured to be about 0.20 mm.

The electrode structure 30 is an electrode body including sheet-like negative electrode bodies 31, positive electrode bodies 32, and a separator 33, in which the negative electrode bodies 31 and the positive electrode bodies 32 are alternately stacked and integrated. Specifically, the electrode structure 30 is formed by overlapping the negative electrode body 31 and the positive electrode body 32 with the separator 33 interposed therebetween and winding them flat. The separator 33 is disposed entirely between the layers of the negative electrode body 31 and the positive electrode body 32, and insulates the negative electrode body 31 from the positive electrode body 32.
The electrode structure 30 can be integrated by winding as shown in FIG. 2, or by various other methods such as stacking or folding.

The negative electrode body 31 is a sheet-like member that includes a negative electrode current collector foil made of a metal material and a negative electrode active material coated on the negative electrode current collector foil. The negative electrode current collector foil is made of a metal foil such as copper or stainless steel. The negative electrode active material is, for example, silicon oxide, graphite, hard carbon, lithium titanate, LiAl, etc.

A negative electrode lead tab 311 is connected to the outer peripheral end of the negative electrode body 31. The negative electrode lead tab 311 is electrically connected via the uneven portion 20 of the negative electrode can 11 described above. The negative electrode lead tab 311 extends from the negative electrode 312 arranged on the outermost periphery along the negative electrode longitudinal direction. The negative electrode lead tab 311 is integrally formed from the same material as the negative electrode current collector foil of the negative electrode body 31.

The positive electrode body 32 is a sheet-like member that includes a positive electrode current collector foil made of a metal material and a positive electrode active material coated on the positive electrode current collector foil. The positive electrode current collector foil is made of a metal foil such as aluminum or stainless steel. The positive electrode active material is a composite oxide containing lithium and a transition metal, such as lithium cobalt oxide, lithium titanate, or lithium manganate.

A positive electrode lead tab 321 is connected to the outer peripheral end of the positive electrode body 32. The positive electrode lead tab 321 is electrically connected via the uneven portion 20 of the positive electrode can 12 described above. The positive electrode lead tab 321 extends from the positive electrode 322 arranged on the outermost periphery along the positive electrode longitudinal direction. The positive electrode lead tab 321 is integrally formed from the same material as the positive electrode current collector foil of the positive electrode body 32.

In addition, in the nonaqueous electrolyte secondary battery 1 of this embodiment, the negative electrode 312 is electrically connected to the inner surface of the negative electrode can 11 via the negative electrode lead tab 311, and the positive electrode 322 is electrically connected to the inner surface of the positive electrode can 12 via the positive electrode lead tab 321.
As described above, the negative electrode lead tab 311 and the positive electrode lead tab 321 are made of the same material as the negative electrode current collector foil and the positive electrode current collector foil. These may be extensions of the negative electrode current collector foil and the positive electrode current collector foil, or separate lead tabs fixed to the current collector foil by welding or the like. Furthermore, lead tabs made of a different material may be used as necessary.

In this embodiment, the uneven portion 20 is formed on the inner surface of the negative electrode can 11. The surface of the negative electrode lead tab 311 facing the inner surface of the negative electrode can 11 is solid-state joined to the uneven portion 20 on the inner surface of the negative electrode can 11 by pressure welding. This electrically connects the negative electrode can 11 and the electrode structure 30.
Similarly, uneven portion 20 is formed on the inner surface of positive electrode can 12. Then, the surface of positive electrode lead tab 321 facing the inner surface of positive electrode can 12 is solid-state bonded to uneven portion 20 on the inner surface of positive electrode can 12 by pressure welding. In this way, positive electrode can 12 and electrode structure 30 are electrically connected to each other.
In this way, the negative electrode can 11 and the positive electrode can 12 are pressure-welded to the negative electrode lead tab 311 and the positive electrode lead tab 321 by the uneven portion 20 formed on the inner surface of the can, so that the negative electrode lead tab 311 and the positive electrode lead tab 321 deform to match the shape of the uneven portion 20, increasing the contact area of each connection. Therefore, it is possible to realize a stable conductive connection that is easy to manufacture and is not easily affected by changes in the shape of the electrode structure due to charging and discharging, etc.

The uneven portion 20 may be composed of a convex portion as shown in FIG. 1, for example. The uneven portion 20 may also be composed of a concave portion formed on the inner surface of the negative electrode can 11 or the positive electrode can 12. FIG. 3 shows an example in which the uneven portion 20 is composed of a convex portion. Specifically, for example, as shown in FIG. 3(a), the convex portion 20a of the uneven portion 20 may have a shape with a sharp tip. In this case, the uneven portion 20 is pressed against and penetrates the negative electrode lead tab 311 or the positive electrode lead tab 321, exposing a new interface on the lead tab. The contact between this exposed surface and the uneven portion 20 significantly reduces the contact resistance.

Also, as shown in FIG. 3(b), the protruding portion 20b of the uneven portion 20 may have a flat tip. In this case, even if the protruding portion 20b is pressed against the negative electrode lead tab 311 and the positive electrode lead tab 321, deformation of the negative electrode lead tab 311 and the positive electrode lead tab 321 can be suppressed, and the risk of a short circuit can be reduced. The tip of the protruding portion 20b may be a smooth surface, such as a curved surface such as a hemisphere, in addition to a flat shape.

When the uneven portion 20 is made of protrusions, the protrusions can be formed by various methods. Among these, when the uneven portion is formed by fixing the protrusions to the inner surface of the negative electrode can 11 or the positive electrode can 12, it is preferable because the desired shape of the protrusions can be formed. The protrusions are formed from a material having electrical conductivity, such as metal or carbon material. Specifically, for example, a solidified conductive paste or a metal mesh can be used as the protrusions. When a solidified conductive paste is used as the protrusions, a conductive paste with an appropriately adjusted viscosity is applied in dots to the bottom surface of the can, and then the solidified conductive paste can be obtained by heating and drying. In addition, the metal mesh can be fixed to the can by a method such as gluing it to the can using a conductive paste or welding it.

When the uneven portion 20 is made of a recess in the negative electrode can 11 or the positive electrode can 12, the uneven portion 20 can be formed by removing a portion of the inner surface of the can. The uneven portion 20 can be formed by various methods, for example, by at least one method selected from etching, cutting, and press processing. When the uneven portion 20 is made of a recess in this way, it is a preferred embodiment in that the number of parts can be reduced and the can and the lead tab can be in direct contact.

In this embodiment, in the example shown in FIG. 1 and FIG. 2, the negative electrode lead tab 311 and the positive electrode lead tab 321 are folded back once after extending from the negative electrode body 31 and the positive electrode body 32, respectively. This embodiment is not limited to this, and as shown in FIG. 4, the negative electrode lead tab 311 or the positive electrode lead tab 321 may be folded back multiple times and placed between the uneven portion 20 and the electrode structure 30. In this way, by arranging the negative electrode lead tab 311 or the positive electrode lead tab 321 in multiple layers, the shape of the uneven portion 20 can be absorbed and an internal short circuit of the electrode structure 30 can be prevented, which is a preferred embodiment. Such multiple-layer lead tabs may be either the negative electrode lead tab 311 or the positive electrode lead tab 321, or both.

In addition, in this embodiment, the uneven portion 20 is formed on both the negative electrode can 11 and the positive electrode can 12, but this is not limited to this, and the present invention can also be applied when the uneven portion 20 is formed on only one of them.

As shown in Figures 1, 2, and 4, the gasket 13 is formed in an annular shape along the inner circumferential surface of the positive electrode can 12, and the tip of the negative electrode can 11 is placed inside the annular groove.

Examples of materials for such gaskets 13 include plastic resins such as polypropylene resin (PP), polyphenyl sulfide (PPS), polyethylene terephthalate (PET), polyamide, liquid crystal polymer (LCP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (PFA), polyether ether ketone resin (PEEK), polyether nitrile resin (PEN), polyether ketone resin (PEK), polyarylate resin, polybutylene terephthalate resin (PBT), polycyclohexane dimethylene terephthalate resin, polyether sulfone resin (PES), polyamino bismaleimide resin, polyetherimide resin, and fluororesin.

A sealant may also be applied to the inner surface of the annular groove of the gasket 13. Examples of such sealants include asphalt, epoxy resin, polyamide resin, and butyl rubber adhesive. After the sealant is applied to the inside of the annular groove, it is dried before use.

The gasket 13 is sandwiched between the negative electrode can 11 and the positive electrode can 12, and at least a portion of it is compressed. The compression ratio at this time is not particularly limited, and should be within a range that can reliably seal the inside of the nonaqueous electrolyte secondary battery 1 and does not cause breakage of the gasket 13.

The separator 33 is a member that allows lithium ions to pass through. The separator 33 is formed, for example, from a polyolefin resin porous film, a glass nonwoven fabric, a resin nonwoven fabric, a laminate of cellulose fibers, etc.

The electrolytic solution may be a non-aqueous electrolyte in which a supporting salt is dissolved in a non-aqueous solvent.
As the non-aqueous solvent, various compounds such as cyclic carbonates, chain carbonates, chain ethers, etc. can be used. For example, these can be a single or mixed solvent of organic solvents such as γ-butyrolactone (GBL), propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl formate, 1,2-dimethoxyethane (DME), tetrahydrofuran (THF), dioxolane, dimethylformamide (DMF), glyme, sulfolane, acetonitrile, etc. In addition, as the supporting salt, for example, LiClO ₄ , LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiN(CF ₃ SO ₂ ) ₂ , LiN(SO ₂ F) ₂ , etc. can be used.

As the supporting salt, for example, _LiClO4 , _LiPF6 , _{LiBF4 , LiCF3SO3} , LiN( _CF3SO2 ) ₂ , LiN( _SO2F ) ₂ , etc. may be used. Furthermore, an ionic liquid may be used as _the supporting salt.

In addition to the solvent and supporting salt, various additives can be added.
Furthermore, instead of the electrolytic solution, a gel electrolyte in which these nonaqueous electrolytic solutions are impregnated and absorbed in a highly liquid-absorbent porous polymer, a polymer solid electrolyte in which the lithium salt is solid-dissolved in a polymer such as polyethylene oxide or a crosslinked polyphosphazene, or an inorganic solid electrolyte such as _Li3N or LiI can also be used.

The present invention is not limited to the above-described embodiment, but can be implemented in various forms within its technical scope.

Next, a method for manufacturing the nonaqueous electrolyte secondary battery of this embodiment will be described.
The method for manufacturing a nonaqueous electrolyte secondary battery of the present embodiment is a method for manufacturing a nonaqueous electrolyte secondary battery including: an exterior body in which a first container and a second container are insulated and sealed; and an electrode structure including a first electrode and a second electrode that are contained in the exterior body and electrically connected to the first container and the second container, respectively; at least one of the first electrode and the second electrode further includes a lead tab electrically connected to the electrode; and the lead tab is pressure-welded to connect to an uneven portion formed on an inner surface of at least one of the first container and the second container.
More specifically, the method includes at least the steps of forming an uneven portion on the inner surface of at least one of a first container and a second container, preparing an electrode structure, accommodating the electrode structure in an accommodating space formed by the first container and the second container, and hermetically sealing the first container and the second container to pressure-connect the uneven portion to a lead tab of the electrode structure.

The step of forming the unevenness on the inner surface of the container (negative electrode can and positive electrode can) may be either a step of forming a convex portion on the inner surface of the container or a step of forming a concave portion. In the case of the step of forming the convex portion on the inner surface of the container, for example, as described above, a method of applying a conductive paste to the inner surface of the container and drying and solidifying it, or welding a metal mesh to the inner surface of the container or bonding it with a conductive adhesive can be used.
Furthermore, in the case of the step of forming a recess on the inner surface of the container, this can be carried out by removing a part of the inner surface of the container by a method such as etching, cutting, or pressing.

The process for producing the electrode structure involves stacking a sheet-shaped negative electrode body 31 and a sheet-shaped positive electrode body 32 with a sheet-shaped separator 33 in between, and then integrating them by various methods such as winding, laminating, and folding to obtain the electrode structure 30.
Here, the negative electrode body 31 is obtained by applying a slurry-like negative electrode mixture to a negative electrode current collector (negative electrode current collector foil) made of metal foil and drying it. Similarly, the positive electrode body 32 is obtained by applying a slurry-like positive electrode mixture to a positive electrode current collector (positive electrode current collector foil) made of metal foil and drying it. The negative electrode mixture and the positive electrode mixture can be obtained by mixing the negative electrode active material and the positive electrode active material, respectively, with a conductive assistant made of graphite or the like and a binder made of resin, and further dispersing them in a solvent made of an organic solvent. Alternatively, the negative electrode body 31 may be formed by attaching a foil-like lithium metal or lithium alloy to the negative electrode current collector foil instead of the negative electrode mixture.
Furthermore, the uncoated portions of the negative electrode current collector foil and the positive electrode current collector foil can be extended from the electrode structure 30 to form the negative electrode lead tab 311 and the positive electrode lead tab 321. Separate lead tabs may be welded to the uncoated portions of the negative electrode current collector foil and the positive electrode current collector foil, respectively.

In the case of a coin-type (button-type) battery as shown in FIGS. 1 and 2, the step of housing the electrode structure is carried out, for example, as follows.
First, the negative electrode lead tab 311 and the positive electrode lead tab 321 extending from the electrode structure 30 obtained in the above-mentioned process are folded back to positions facing the uneven portions 20 of the negative electrode can 11 and the positive electrode can 12, respectively, and then the electrode structure 30 is disposed so as to be located between the negative electrode can 11 and the positive electrode can 12. At this time, the gasket 13 is previously incorporated into the negative electrode can 11.
Furthermore, an electrolyte is poured into at least one of the negative electrode can 11 and the positive electrode can 12 , and then the negative electrode can 11 is housed in the positive electrode can 12 .

In the case of a coin-type (button-type) battery as shown in Fig. 2, for example, the step of sealing the first container and the second container is performed by crimping the periphery of the opening of the positive electrode can 12 to the negative electrode can 11 side after the step of housing the electrode structure described above, with the negative electrode can 11 and the positive electrode can 12 insulated from each other via a gasket 13. By sealing the battery in this manner, the housed electrode structure 30 is pressurized in the thickness direction of the battery. This allows the lead tab (negative electrode lead tab 311 or positive electrode lead tab 321) to be pressure-welded and connected to the uneven portion 20, making the conductive connection between them stable.
The pressure connection between the lead tab and the uneven portion 20 can be achieved by crimping in the manufacture of a coin battery, or by hermetic sealing if the exterior structure allows pressure to be applied to the electrode structure 30 .

1: nonaqueous electrolyte secondary battery 10: exterior body 11: negative electrode can
12: Positive electrode can 13: Gasket 20: Concave and convex portions 20a, 20b: Convex portion tip 30: Electrode structure 31: Negative electrode body 311: Negative electrode lead tab 312: Negative electrode 32: Positive electrode body 321: Positive electrode lead tab 322: Positive electrode 33: Separator

Claims (5)

an exterior body in which a first container and a second container are insulated and sealed; and an electrode structure including a first electrode and a second electrode housed in the exterior body and electrically connected to the first container and the second container, respectively;
At least one of the first electrode and the second electrode further includes a lead tab electrically connected to the electrode;
a protrusion-recess portion having protrusions which are a solidified body of a conductive paste is formed on an inner surface of at least one of the first container and the second container , and the protrusion-recess portion and the lead tab are solid-phase bonded by pressure welding. 2. The nonaqueous electrolyte secondary battery according to claim 1, wherein the protrusion has a sharp tip. 2. The nonaqueous electrolyte secondary battery according to claim 1, wherein the protrusion has a smooth surface at its tip. 4. The nonaqueous electrolyte secondary battery according to claim 1 , wherein the lead tabs are arranged in a plurality of layers in a planar position between the projections and recesses and the electrode structure. A method for manufacturing a nonaqueous electrolyte secondary battery comprising: an exterior body in which a first container and a second container are insulated and sealed; and an electrode structure including a first electrode and a second electrode housed in the exterior body and electrically connected to the first container and the second container, respectively, the method comprising the steps of:
At least one of the first electrode and the second electrode further includes a lead tab electrically connected to the electrode;
a protrusion which is a solidified conductive paste is fixed to an inner surface of at least one of the first container and the second container to form a concave-convex portion , and the concave-convex portion and the lead tab are pressure-welded to be connected.

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