WO2021149541A1

WO2021149541A1 - Secondary battery

Info

Publication number: WO2021149541A1
Application number: PCT/JP2021/000720
Authority: WO
Inventors: 健太江口
Original assignee: 株式会社村田製作所
Priority date: 2020-01-20
Filing date: 2021-01-12
Publication date: 2021-07-29

Abstract

Provided is a secondary battery having an electrode assembly. In the secondary battery, each of a positive electrode collector tab and a negative electrode collector tab obliquely extends from the electrode assembly.

Description

Secondary battery

The present invention relates to a secondary battery. In particular, the present invention relates to a secondary battery including an electrode assembly in which electrode constituent layers including a positive electrode, a negative electrode and a separator are laminated.

Since the secondary battery is a so-called storage battery, it can be repeatedly charged and discharged, and is used for various purposes. For example, secondary batteries are widely used in mobile devices such as mobile phones, smartphones and notebook computers.

Japanese Patent No. 5317195 U.S. Patent Application Publication No. 2015/0221925

The inventor of the present application noticed that there was a problem to be overcome with the conventional secondary battery, and found that it was necessary to take measures for that purpose. Specifically, the inventor of the present application has found that there are the following problems.

For example, as shown in the schematic top view of FIG. 8A, in the conventional coin-shaped (or button-shaped) secondary battery, the positive electrode current collecting tab (23a) and the negative electrode current collecting tab (23b) face each other and face each other. An electrode configuration that extends in the opposite direction and is arranged is being studied (for example, Patent Documents 1 and 2). However, according to the inventor of the present application, in such an electrode configuration in which the current collecting tabs face each other in opposite directions, the dimension (or "tab width") in the width direction of the current collecting tab can be increased, but on the other hand. In order to secure the dimension (or "tab length") of the current collecting tab in the extending direction, for example, the electrode must be cut (or notched) at two places above and below, and the area of the electrode body is small. As a result, it was found that there was a problem that the capacity of the battery itself was significantly reduced.

Therefore, for example, in order to increase the area of the electrode body, the inventor of the present application cuts (or cuts out) only one upper electrode, for example, as shown in the schematic top view of FIG. 8 (b), and positive electrode. A secondary battery in which the current collecting tab (33a) and the negative electrode current collecting tab (33b) are arranged side by side was examined. However, such a configuration in which the two current collecting tabs shown in FIG. 8B are arranged in parallel has a larger area of the electrode body than the configuration shown in FIG. 8A, but is in the width direction of the current collecting tabs. It was found that the dimensions (or "tab width") decreased and the resistance, especially the current collecting resistance, increased. Further, in order to further increase the dimension (or "tab length") of the current collecting tab in the extending direction, the area of the electrode body must be further reduced as in the configuration shown in FIG. 8A, and the battery It was also found that there was a problem that the capacity of itself was significantly reduced.

Thus, it was found for the first time by the research of the inventor of the present application that "electrode area", "tab width" and "tab length" are closely and complicatedly related to each other. Based on these findings, the inventor of the present application finds that the arrangement and design of the "current collector tab" as well as the cut (or notch) of the electrode is very important in the development of the secondary battery, and there is room for further improvement. I found out that there is.

The present invention has been made in view of such a problem. That is, the main object of the present invention is to further improve the arrangement and design of the current collecting tabs in the secondary battery.

As a result of diligent research, the inventor of the present application arranges the positive electrode current collecting tab and the negative electrode current collecting tab that can extend from the electrode assembly "diagonally", respectively, and more specifically, the extending direction of the positive electrode current collecting tab and the negative electrode. By arranging the current collecting tabs so that they form corners (or corners) with each other, more appropriate "electrode area", "tab width" and / or "tab length" can be obtained. It was found that the degree of freedom in tab design increases significantly with them. As a result, the invention of the secondary battery which achieved the above-mentioned main purpose was completed.

INDUSTRIAL APPLICABILITY The present invention provides a secondary battery having an electrode assembly in which a positive electrode current collecting tab and a negative electrode current collecting tab extend "diagonally" from the electrode assembly. .. Hereinafter, in the present disclosure, the above-mentioned secondary battery may be referred to as "the secondary battery of the present disclosure".

In the secondary battery of the present invention, by arranging the "positive electrode current collecting tab" and the "negative electrode current collecting tab" that can extend from the electrode assembly "diagonally", more specifically, the "positive electrode current collecting tab" is extended. By arranging the "outward direction" and the "extending direction of the negative electrode current collecting tab" so as to form a corner (corner) with each other, the "electrode area", "tab width" and / or " "Tab lengths" can be obtained, and together with them, the degree of freedom in tab design can be increased more significantly.

FIG. 1 is a cross-sectional view schematically showing the configuration of the electrode assembly (FIG. 1 (a): non-winding plane laminated type, FIG. 1 (b): wound type). FIG. 2 is a schematic exploded top view schematically showing an electrode assembly and a current collecting tab included in a secondary battery according to an embodiment of the present invention. FIG. 3 is a schematic top view schematically showing an electrode assembly and a current collecting tab included in a secondary battery according to an embodiment of the present invention. FIG. 4 is a schematic top view schematically showing an electrode assembly and a current collecting tab used in Comparative Examples and Examples (FIG. 4 (a): Comparative Example 1, FIG. 4 (b): Comparative Example 2, FIG. 4 (c) Example 1). FIG. 5 is a graph showing a comparison between the examples and the comparative examples regarding the “electrode area”. FIG. 6 is a graph showing a comparison between an example and a comparative example regarding the relationship between the “tab area” and the “electrode area change rate” (tab length 1 mm). FIG. 7 is a graph showing a comparison between an example and a comparative example regarding the relationship between the “tab area” and the “electrode area change rate” (tab length 2 mm). FIG. 8 is a schematic top view schematically showing the electrode assembly and the current collecting tab used in the comparative example (previous).

Hereinafter, the present invention will be described in more detail with reference to the secondary battery according to the embodiment of the present invention. Although the description will be given with reference to the drawings as necessary, the various elements and configurations in the drawings are merely schematically and exemplary for the understanding of the present invention, and the appearance and / or dimensional ratio and the like are shown. It can be different from the real thing.

The "cross-sectional view" described directly or indirectly herein is, for example, along the stacking direction or stacking direction of the electrode assembly or electrode constituent layer or electrode constituent unit that can constitute a secondary battery. It is based on a virtual cross section of the secondary battery (see FIG. 1). Similarly, the direction of "thickness" as described directly or indirectly herein is based on the stacking direction of the electrode materials that may constitute the secondary battery. For example, in the case of a "plate-shaped thick secondary battery" such as a button type (or coin type), the direction of "thickness" corresponds to the plate thickness direction of such a secondary battery. As used herein, "planar view" is based on a sketch of an object viewed from above or below along the direction of such thickness.

Further, the "vertical direction" and the "horizontal direction" used directly or indirectly in the present specification correspond to the vertical direction and the horizontal direction in the figure, respectively. Unless otherwise specified, the same code or symbol shall indicate the same member or part or the same meaning. In one preferred embodiment, it can be considered that the vertical downward direction (that is, the direction in which gravity acts) corresponds to the "downward direction" and the opposite direction corresponds to the "upward direction".

[Basic configuration of secondary battery]
The term "secondary battery" as used herein refers to a battery that can be repeatedly charged and discharged. Therefore, the secondary battery according to the embodiment of the present invention is not excessively bound by its name, and may include, for example, a power storage device.

The secondary battery according to the embodiment of the present invention has, for example, an electrode assembly having a structure in which at least one or more electrode constituent layers or electrode constituent units including at least a positive electrode, a negative electrode and a separator are laminated. It consists of. For example, FIGS. 1 (a) and 1 (b) illustrate the electrode assembly 10. As shown, the positive electrode 1 and the negative electrode 2 may be stacked with each other via the separator 3 to form an electrode constituent layer (or electrode constituent unit) 5. At least one or more of these electrode constituent layers 5 may be laminated to form the electrode assembly 10. In a secondary battery, such an electrode assembly may be enclosed in an exterior body together with an electrolyte (for example, a non-aqueous electrolyte). The structure of the electrode assembly is not necessarily limited to the planar laminated structure (see FIG. 1A), and for example, the electrode unit (or electrode) including the positive electrode, the negative electrode, and the separator arranged between the positive electrode and the negative electrode. It may have a winding structure (see FIG. 1B) (for example, a jelly roll structure) formed by winding a constituent layer or an electrode constituent unit in a roll shape. That is, as shown in FIG. 1A, for example, the electrode assembly 10 may have a flat laminated structure in which the electrode constituent layers 5 are laminated so as to be stacked on each other. Alternatively, the electrode assembly 10 may have a winding structure in which the electrode constituent layer 5 extending in a strip shape for a relatively long time is wound in a roll shape, for example, as shown in FIG. 1 (b). ..
Note that FIG. 1B merely illustrates a wound structure of the electrode assembly, and the electrode assembly is placed inside the exterior with the cross section shown in FIG. 1B set to "upward" or "downward". It may be placed in.
Further, for example, the electrode assembly may have a so-called stack-and-folding structure in which a positive electrode, a separator and a negative electrode are laminated on a long film and then folded.

The positive electrode is composed of at least a positive electrode material layer and, if necessary, a positive electrode current collector. The positive electrode material layer contains a positive electrode active material as an electrode active material. The positive electrode current collector may or may not be present in the positive electrode. When a positive electrode current collector is present on the positive electrode, a positive electrode material layer may be provided on at least one surface of the positive electrode current collector on the positive electrode. For example, each of the plurality of positive electrodes in the electrode assembly may have positive electrode material layers provided on both sides of the positive electrode current collector, or positive electrode material layers may be provided on only one side of the positive electrode current collector. It may be the one that exists. For example, the positive electrode current collector may have a foil form. That is, the positive electrode current collector may be composed of the metal foil.

The negative electrode is composed of at least a negative electrode material layer and, if necessary, a negative electrode current collector. The negative electrode material layer contains a negative electrode active material as an electrode active material. The negative electrode current collector may or may not be present in the negative electrode. When the negative electrode current collector is present in the negative electrode, the negative electrode material layer may be provided on at least one surface of the negative electrode current collector in the negative electrode. For example, each of the plurality of negative electrodes in the electrode assembly may have negative electrode material layers provided on both sides of the negative electrode current collector, or negative electrode material layers may be provided on only one side of the negative electrode current collector. It may be the one that exists. For example, the negative electrode current collector may have a foil form. That is, the negative electrode current collector may be composed of the metal foil.

The electrode active material, that is, the positive electrode active material and the negative electrode active material, which can be contained in the positive electrode material layer and the negative electrode material layer, are substances that can be directly involved in the transfer of electrons in the secondary battery, respectively, and are charged and discharged, that is, the battery reaction. It is the main material of the positive electrode and the negative electrode.

More specifically, ions can be brought to the electrolyte due to the "positive electrode active material that can be contained in the positive electrode material layer" and the "negative electrode active material that can be contained in the negative electrode material layer". Such ions may move between the positive electrode and the negative electrode to transfer electrons and charge / discharge.

The positive electrode material layer and the negative electrode material layer may be particularly layers capable of occluding and releasing lithium ions. That is, the secondary battery according to the embodiment of the present invention is, for example, a non-aqueous electrolyte secondary battery in which lithium ions can move between the positive electrode and the negative electrode via a non-aqueous electrolyte to charge and discharge the battery. It may be.

When lithium ions are involved in charging / discharging, the secondary battery according to the embodiment of the present invention can correspond to a so-called "lithium ion battery". The lithium ion battery has a layer in which the positive electrode and the negative electrode can occlude and release lithium ions.

The positive electrode active material of the positive electrode material layer may be composed of, for example, granules, and a binder may be contained in the positive electrode material layer for more sufficient contact between particles and shape retention. A conductive aid may be included in the positive electrode material layer to facilitate the transfer of electrons that can drive the battery reaction.

The negative electrode active material of the negative electrode material layer may be composed of, for example, granules, and a binder may be contained in the negative electrode material layer for more sufficient contact between particles and shape retention. A conductive auxiliary agent may be contained in the negative electrode material layer in order to further smooth the transfer of electrons that can promote the battery reaction.

As described above, the positive electrode material layer and the negative electrode material layer can also be referred to as a "positive electrode mixture layer" and a "negative electrode mixture layer", respectively, because of the form in which a plurality of components are contained.

The positive electrode active material may be, for example, a substance that contributes to the occlusion and release of lithium ions. From this point of view, 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.

That is, in the positive electrode material layer of the secondary battery according to the embodiment of the present invention, such a lithium transition metal composite oxide may be 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 part of the transition metal thereof replaced with another metal.

Although such a positive electrode active material may be contained as a single species, it may be contained in combination of two or more species.

The binder that can be contained in the positive electrode material layer is not particularly limited, but is limited to polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer and polytetrafluoroethylene. At least one species selected from the group consisting of the above can be mentioned.

The conductive auxiliary agent that can be contained in the positive electrode material layer is not particularly limited, but is limited to carbon black such as thermal black, furnace black, channel black, ketjen black and acetylene black, graphite, carbon nanotubes, and vapor phase growth. At least one selected from carbon fibers such as carbon fibers, metal powders such as copper, nickel, aluminum and silver, and polyphenylene derivatives can be mentioned.

The thickness dimension of the positive electrode material 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 dimension of the positive electrode material layer is the thickness inside the secondary battery, and the average value of the measured values at any 10 points may be adopted.

The negative electrode active material may be a substance that contributes to the occlusion and release of lithium ions. From this point of view, the negative electrode active material may be, for example, various carbon materials, oxides, and / or lithium alloys, metallic lithium, and the like.

Examples of various carbon materials for the negative electrode active material include graphite (specifically, natural graphite and / or artificial graphite, etc.), hard carbon, soft carbon, diamond-like carbon, and the like. In particular, graphite has high electron conductivity and excellent adhesion to a negative electrode current collector.

As the oxide of the negative electrode active material, at least one selected from the group consisting of silicon oxide, tin oxide, indium oxide, zinc oxide, lithium oxide and the like can be mentioned.

Such an oxide may be amorphous as its structural form. This is because deterioration due to non-uniformity such as grain boundaries or defects is less likely to occur.

The lithium alloy of the negative electrode active material may be an alloy of a metal that can be alloyed with lithium, for example, Al, Si, Pb, Sn, In, Bi, Ag, Ba, Ca, Hg, Pd, Pt, Te, It may be a binary, ternary or higher alloy of a metal such as Zn or La and lithium.

Such an alloy may be amorphous as its structural form. This is because deterioration that can be caused by non-uniformity such as grain boundaries or defects is less likely to occur.

The binder that can be contained in the negative electrode material layer is not particularly limited, but is at least one selected from the group consisting of styrene-butadiene rubber, polyacrylic acid, polyvinylidene fluoride, polyimide-based resin, and polyamide-imide-based resin. Can be mentioned.

The conductive auxiliary agent that can be contained in the negative electrode material layer is not particularly limited, but is limited to carbon black such as thermal black, furnace black, channel black, ketjen black and acetylene black, graphite, carbon nanotubes, and vapor phase growth. At least one selected from carbon fibers such as carbon fibers, metal powders such as copper, nickel, aluminum and silver, and polyphenylene derivatives can be mentioned.

The thickness dimension of the negative electrode material 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 dimension of the negative electrode material layer is the thickness inside the secondary battery, and the average value of the measured values at any 10 points may be adopted.

The positive electrode current collector and the negative electrode current collector that can be used for the positive electrode and the negative electrode (hereinafter, both may be collectively referred to simply as “current collector”) are electrons generated by the electrode active material due to the battery reaction. It is a member that can collect and supply. Such an electrode current collector may be a sheet-shaped metal member. Further, such an electrode current collector may have a perforated or perforated form. For example, the current collector may be a metal leaf, a punching metal, a net or an expanded metal, a plate, or the like.

The positive electrode current collector that can be used for the positive electrode may be made of a metal foil containing at least one selected from the group consisting of aluminum, stainless steel (SUS), nickel and the like. The positive electrode current collector may be, for example, an aluminum foil.

The negative electrode current collector that can be used for the negative electrode may be made of a metal foil containing at least one selected from the group consisting of copper, stainless steel (SUS), nickel and the like. The negative electrode current collector may be, for example, a copper foil.

In the present disclosure, "stainless steel" (SUS) refers to, for example, stainless steel defined in "JIS G0203 steel terminology", and is an alloy steel containing chromium or chromium and nickel. It's okay.

The thickness dimensions of the positive electrode current collector and the negative electrode current collector are 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. Each thickness dimension 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 measured values at any 10 points may be adopted.

The separator that can be used for the positive electrode and the negative electrode is a member that can be provided from the viewpoint of preventing a short circuit due to contact between the positive electrode and the negative electrode and retaining the electrolyte. In other words, it can be said that the separator is a member capable of passing ions while preventing electronic contact between the positive electrode and the negative electrode.

For example, the separator is a porous or microporous insulating member, and may have a film morphology due to its small thickness. Although only an example, a microporous polyolefin membrane may be used as the separator.

The microporous membrane that can be used as a separator may contain, for example, only polyethylene (PE) or polypropylene (PP) as the polyolefin. Furthermore, the separator may be a laminate that can be 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 coat layer and / or an adhesive layer or the like. The surface of the separator may have adhesiveness.

The thickness dimension 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 dimension 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 measured values at any 10 points may be adopted.

In the present invention, the separator should not be particularly bound by its name, and may be a solid electrolyte, a gel-like electrolyte, and / or insulating inorganic particles having the same function.

In the secondary battery according to the embodiment of the present invention, for example, an electrode constituent layer including a positive electrode, a negative electrode and a separator, or an electrode assembly including an electrode constituent unit may be enclosed in an exterior body together with an electrolyte. The electrolyte can assist in the movement of metal ions released from the electrodes (positive electrode and / or negative electrode). The electrolyte may be an organic electrolyte and / or a "non-aqueous" electrolyte comprising organic solvents and the like, or it may be a "water-based" electrolyte containing water.

When the positive electrode and the negative electrode have a layer capable of occluding and releasing lithium ions, the electrolyte is an "non-aqueous" electrolyte (hereinafter referred to as "non-aqueous electrolyte") containing an organic electrolyte and / or an organic solvent and the like. Is preferable. That is, it is preferable that the electrolyte is a non-aqueous electrolyte. In the electrolyte, there will be metal ions released from the electrodes (positive electrode and / or negative electrode), and therefore the electrolyte can assist in the movement of the metal ions in the battery reaction.

The secondary battery according to the embodiment of the present invention is preferably a non-aqueous electrolyte secondary battery in which a "non-aqueous" electrolyte containing a "non-aqueous" solvent and a solute is used as the electrolyte. The electrolyte may have a form such as liquid or gel (note that the “liquid” non-aqueous electrolyte is also referred to as “non-aqueous electrolyte solution” in the present specification).

The non-aqueous electrolyte is preferably an electrolyte containing a non-aqueous solvent and a solute. The specific solvent for the non-aqueous electrolyte may contain at least carbonate. Such carbonates may be cyclic carbonates and / or chain carbonates.

Although not particularly limited, the cyclic carbonates include at least one selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC) and vinylene carbonate (VC). be able to.

Examples of the chain carbonates include at least one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC) and dipropyl carbonate (DPC).

By way of example only, in one preferred embodiment of the present invention, a combination of cyclic carbonates and chain carbonates may be used as the non-aqueous electrolyte, for example ethylene carbonate (EC) and diethyl carbonate ( A mixture with DEC), a mixture of ethylene carbonate (EC) and ethyl methyl carbonate (EMC), and the like may be used. As a specific non-aqueous electrolyte solute, for example, a Li salt such as _{LiPF 6} and / or LiBF _{4 may be used.}

The exterior body of the secondary battery can house or enclose, for example, an electrode assembly having a structure in which at least one or more electrode constituent layers or electrode constituent units including a positive electrode, a negative electrode and a separator are laminated. It is a member. In the present invention, the exterior body of the secondary battery is not particularly limited as long as it can accommodate the above-mentioned electrode assembly. A conventionally known exterior body can be appropriately used as needed.

The exterior body is preferably a metal exterior body. The metal exterior body may have, for example, a two-part configuration of a cup-shaped member and a lid-shaped member.

In the present disclosure, the "cup-shaped member" has a side surface portion corresponding to a body portion and a main surface portion (in a typical embodiment, for example, an upper surface or a lower surface) continuous with the side surface portion, and a hollow portion is formed inside. It means such a member.
In the present disclosure, the "lid-shaped member" means a member that can be provided to cover such a cup-shaped member. The lid-shaped member may be, for example, a single member (typically a flat plate-shaped member) extending in the same plane. In the exterior body, the cup-shaped member and the lid-shaped member may be arbitrarily combined so that the cup-shaped member and the lid-shaped member engage, connect, or fit with each other.

It is preferable that the cup-shaped member and the lid-shaped member are fitted and joined to each other. In the case of a metal exterior body, it is preferable that an insulating member including an insulating material is arranged between the cup-shaped member and the lid-shaped member. With such a configuration, the cup-shaped member and the lid-shaped member can function independently as electrode terminals.

With such an insulating member, it is possible to achieve sealing (or sealing) between the cup-shaped member and the lid-shaped member while electrically insulating the cup-shaped member and the lid-shaped member. Here, there is no particular limitation on the insulating material that can form the insulating member. As the insulating member, for example, a member including a thermoplastic resin can be used.

In the present disclosure, the exterior body may be a flexible case having a laminated structure or the like, or a hard case having a non-laminated structure such as a metal exterior body. The metal exterior preferably has a non-laminated structure. That is, in the present invention, the metal exterior body is not, for example, a laminated member of a metal sheet / fusion layer / protective layer. Preferably, the metal exterior has a structure composed of a single metal member. For example, the metal exterior body (specifically, each of the cup-shaped member and the lid-shaped member) may be a single member made of a metal such as stainless steel (SUS) or aluminum. The exterior body in the present disclosure may contain an alloy as a metal.
In the present disclosure, the term "single metal member" means that the exterior body does not have a so-called laminated structure in a broad sense, and in a narrow sense, the exterior body (specifically, a cup-shaped member and a lid). It means that each of the shaped members) is a member substantially composed of only metal. Therefore, an appropriate surface treatment may be applied to the surface of the metal exterior body as long as the member is substantially composed of only metal.

The metal exterior can have a relatively thin thickness. For example, the metal exterior body in the present invention may have a thickness dimension of 50 μm or more and less than 200 μm, for example, 50 μm or more and 190 μm or less, 50 μm or more and 180 μm or less, or 50 μm or more and 170 μm or less.

In the present invention, the above configuration (particularly the exterior body) may be appropriately changed or modified as necessary.

[Characteristics of the secondary battery of the present invention]
The secondary battery of the present invention comprises an electrode assembly, and can extend from the electrode assembly as a "positive electrode current collecting tab" and a "negative electrode current collecting tab" (hereinafter, both are collectively referred to as a "collecting tab". It is characterized by the arrangement of). That is, in the secondary battery, the "positive electrode current collecting tab" and the "negative electrode current collecting tab" each extend "diagonally" from the electrode assembly. More specifically, it is characterized in that the "extending direction of the positive electrode current collecting tab" and the "extending direction of the negative electrode current collecting tab" are arranged so as to form a corner (corner portion) with each other.

The secondary battery according to the embodiment of the present invention is, for example, as shown in the top view of FIGS. 2 (a) to 2 (c), particularly FIG. 2 (c), from the electrode assembly (or electrode) 11 to the positive electrode current collecting tab. The negative electrode current collecting tab 13a and the negative electrode current collecting tab 13b each extend "diagonally".

In the present disclosure, the fact that the positive electrode current collecting tab (13a) and the negative electrode current collecting tab (13b) each extend “diagonally” from the electrode assembly (or electrode) (11) is an arbitrary projection in the secondary battery. In the figure (specifically, in a plan view), for example, as shown in FIG. 2 (c), from the electrode assembly (or electrode) (11) to the “positive electrode current collecting tab (13a)” and the “negative electrode current collecting tab (13b)”. Means that each of them extends, and the extending directions form an angle (corner portion) and have a constant angle (for example, “angle θ” shown in FIG. 2 (b) described later). In other words, for example, on one plane, the extending direction of the positive electrode current collecting tab and the extending direction of the negative electrode current collecting tab intersect (in other words, they are non-parallel) to form an angle (corner) having a certain angle. Means that.

In the present disclosure, the "extension direction" of the "collection tab" is defined as the line segment of the portion where the current collection tab and the electrode assembly meet (or the portion where the current collection tab extends from the electrode assembly). means the normal direction extended from the point in a direction extending current collecting tab (e.g. extending the "extending direction X _a of the positive electrode current collector tabs 13a" and "negative electrode current collector tab 13b shown in FIG. 2 (b) Direction X _b ").
The extension direction of the current collection tab is, for example, when two current collection tabs (specifically, the positive electrode current collection tab 13a and the negative electrode current collection tab 13b) are in a line-symmetrical relationship, the axis of symmetry (for example, FIG. 2). In the "diagonal" direction with respect to the direction P ₀ [normal extension direction (see FIG. 8), for example, the axis of symmetry along the 0 o'clock (or 12 o'clock or 24 o'clock) direction of the clock] in the direction (b). There may be.

More specifically, as shown in FIG. 2B, "extending direction X _a of the positive electrode current collecting tab 13a" and "extending direction X _{b of the negative electrode current collecting tab 13b" extending "diagonally".} The "angle θ" of the angle formed by is preferably "15 ° or more and 120 ° or less".

Hereinafter, the "electrode assembly" and the "current collecting tab" included in the secondary battery according to the embodiment of the present invention will be briefly described, and then the "diagonal arrangement of the current collecting tabs", which is a feature of the present invention, will be described. , Will be explained in more detail.

[Electrode assembly]
An electrode assembly or an electrode (see FIG. 1) that can be included in a secondary battery according to an embodiment of the present invention (hereinafter, may be referred to as “secondary battery of the present disclosure”) is a feature of the present invention. As long as the "diagonal" arrangement of the "collection tab" can be achieved, the configuration and shape (particularly the plan-view shape of the main body) are not particularly limited.
For example, as shown in FIG. 2A, in the secondary battery of the present disclosure, the electrode assembly 11 may have a substantially circular (particularly circular) plan view shape in which the main body is partially cut out. preferable.

In the present disclosure, the "main body" of the electrode assembly means the remaining part excluding the "current collection tab" (specifically, the positive electrode current collection tab and the negative electrode current collection tab) described below in a plan view. do.

For example, as shown in FIG. 2A, the main body of the electrode assembly (or electrode) 11 is a circle or substantially a circle (particularly a circle) cut out from a circle or a substantially circular shape (particularly a circle) having a center O and a diameter D. ) It is preferable to have a plan view shape.

Similarly, the main bodies of the positive electrode and the negative electrode included in the electrode assembly 11 also have a circular or substantially circular (particularly circular) plan view shape obtained by cutting out a part thereof from, for example, a circular or substantially circular (particularly circular) having a center O and a diameter D. It is preferable to have.

In the present disclosure, "notched" means, for example, a shape or state obtained by removing a part thereof from a circle or a substantially circular shape, and even if it is formed in such a shape in advance, it is cut and formed later. May be good.

The electrode assembly 11 and the main body of the positive electrode and the negative electrode are circular or substantially circular (particularly circular) with a part cut out from the circular or substantially circular (particularly circular) plan view shape, whereby two current collecting tabs (specifically) are provided. The positive electrode current collecting tab and the negative electrode current collecting tab) can be successfully arranged "diagonally".

In the present disclosure, "circular" or "substantially circular" (including a notched portion) is a concept including a circular (perfect circle) and a figure that can be usually recognized as a circular at first glance. In other words, a "circle" or "substantially circular" (including notched parts) is not limited to a perfect circle (ie, simply a "circle" or "perfect circle"), but is modified from that. It also includes shapes that can normally be included in a "round shape" as recognized by those skilled in the art. For example, not only a circle and a perfect circle, but also the curvature of the arc may be locally different, and further, a shape derived from a circle and a perfect circle such as an ellipse may be used.

The circular diameter D is not particularly limited, and is, for example, 5 mm or more and 30 mm or less, particularly preferably 10 mm.

A portion cut out from such a circle or a substantially circular shape (particularly a circle) (hereinafter, may be referred to as a “virtual circle before the cutout”) is a cutout 12 as shown by a broken line in FIG. 2 (a), for example. To form. In the plan view of the main body (or notch 12) of the electrode assembly 11, the contour of the notched portion (or edge) may consist of at least two sides (for example, sides m and n). preferable. The outline of the notched portion is not limited to that consisting of two sides, and a polygon may be formed. The current collecting tabs (for example, the positive electrode current collecting tab 13a and the negative electrode current collecting tab 13b) can be extended obliquely from the contour of the notched portion including at least two sides.

For example, as shown in FIG. 2A, the two sides (m, n) of the notched portion may form a corner (corner or top), and the “angle φ” of the corner (corner or top). Is preferably less than 180 ° (but not including 0 °).
In other words, as shown in FIG. 2 (b), the two current collecting tabs (for example, the positive electrode current collecting tab 13a and the negative electrode current collecting tab 13b) are facing outward from each other, or "in directions X _a and X _b" . The intersection of straight lines along the notch 12 or two current collection tabs (for example, positive electrode current collection tab 13a and negative electrode current collection tab 13b) is below, or along two sides (m, n), for example, an electrode set. When creating notch portions (two) by notching (cutting) a solid or electrode, it is preferable that straight lines along two sides intersect and the two notched portions overlap.
When the angle φ is less than 180 ° in this way, for example, a configuration (a) in which two current collecting tabs face each other in opposite directions or a configuration in which two current collecting tabs are arranged in parallel (b) as shown in FIG. ) Can be excluded, and the two current collecting tabs (for example, the positive current collecting tab 13a and the negative negative current collecting tab 13b as shown in FIG. 2C) can be arranged “obliquely” with each other.

The angle (corner or top) formed by the two sides (m, n) of the notched portion exists inside or inside the circle in the configuration shown in FIG. 2 (a), but is on the circumference. It may exist.

In the invention of the present disclosure, for example, as shown in FIG. 2C, it is preferable that the electrode assembly 11 has a mirror image symmetrical shape in a plan view. More two sides of a specific cut in-away portion (e.g., sides m, n) a mirror symmetry with respect to a vertical plane including the straight line P ₁ connecting the center O of the circle and a vertex (corner) which forms good. Alternatively planar shape of the electrode assembly 11 may be in the form of line symmetry or symmetry, for example with respect to the straight line P _1. When the electrode assembly has a mirror image symmetrical shape in a plan view, a more appropriate electrode area, tab width and / or tab length, etc. can be obtained, and at the same time, the degree of freedom in tab design can be significantly increased.

In the secondary battery according to the embodiment of the present invention, from such an electrode assembly or the main body of the electrode 11, preferably from a notched portion thereof, and more preferably each side (for example, a side m) of the notched portion. , N), the positive electrode current collecting tab 13a and the negative electrode current collecting tab 13b can be extended “diagonally”, respectively (for example, FIGS. 2A to 2C).
In the illustrated embodiment, the current collecting tab 13a arranged on the left side is used as the positive electrode current collecting tab, but the current collecting tab 13a may be the negative electrode current collecting tab. Similarly, in the illustrated embodiment, the current collecting tab 13b arranged on the right side is used as the negative electrode current collecting tab, but the current collecting tab 13b may be the positive electrode current collecting tab.

[Current collector tab]
In the present disclosure, the "current collecting tab" is particularly limited as long as it can extend from the electrode assembly (specifically, the main body of the electrode assembly, more specifically, the positive electrode and / or the negative electrode). There is no. For example, the positive electrode current collector tab 13a and the negative electrode current collector tab 13b shown in FIG. 2 are, for example, each of a plurality of positive electrode current collectors or negative electrode current collectors that can be provided on each of the positive electrode and / or the negative electrode included in the electrode assembly. It may consist of overlapping protruding portions.
For example, as shown in FIG. 2C, the positive electrode current collecting tab 13a that can extend “diagonally” from the electrode assembly 11 (specifically, the main body of the electrode assembly 11) can form the electrode assembly 11. It may have a configuration in which the protruding portions of the positive electrode current collectors of the plurality of positive electrodes are integrated on the tip side. Similarly, the negative electrode current collecting tab 13b that can extend “diagonally” from the electrode assembly 11 (specifically, the main body of the electrode assembly) is a negative electrode current collecting tab 13b of each of a plurality of negative electrodes that can form the electrode assembly 11. It may have a structure in which the protruding portion of the body is integrated on the tip side.
The positive electrode current collector tab 13a and the negative electrode current collector tab 13b are preferably integrally formed of the same material as the positive electrode current collector and the negative electrode current collector, which can be included in the electrode assembly, respectively, and are particularly characterized in their shape and dimensions. There is no limit.

The current collection tab (positive electrode current collection tab 13a and / or negative electrode current collection tab 13b) is, for example, a virtual circle (upper surface view) in the plan view (top view) of FIG. It is preferable that it is positioned within a substantially circular shape or a perfect circle). With such a configuration, the two current collecting tabs (that is, the positive electrode current collecting tab 13a and the negative electrode current collecting tab 13b) can be arranged "diagonally" respectively. In addition, such an electrode assembly can be successfully and easily housed together with the current collecting tab, for example, in an exterior body having a substantially circular plan view (not shown).

The current collecting tabs (positive electrode current collecting tab 13a and / or negative electrode current collecting tab 13b) may be connected "directly" or "indirectly" to the exterior body. The fact that the current collecting tab is "directly" connected to the exterior means that, for example, if the exterior is a metal exterior, the current collecting tab is electrically connected to the exterior. When the current collecting tab is "indirectly" connected to the exterior body, it means that the current collecting tab is electrically connected to the exterior body via a terminal such as an external output terminal or an external terminal. For example, when the exterior body is a metal exterior body, it is preferable that the external output terminal is attached to the exterior body via an insulating member. The method of connecting the current collector tab to the exterior body is not particularly limited, and a conventionally known connection method may be appropriately used.

The external output terminal may be a metal plate. The metal plate may have a plurality of layers made of different metal materials. The metal plate is preferably attached to the exterior body via an insulating member.

As the "insulating member", for example, a member including a resin material or an elastomer material can be used.

As the resin material, a thermoplastic resin, preferably a heat-sealing resin can be used. Examples of the thermoplastic resin include polyolefin resins such as polyethylene and / or polypropylene and copolymers thereof. As the insulating member, a single-layer film made of a thermoplastic resin or a multilayer film containing a thermoplastic resin can be used. Examples of the multilayer film include a multilayer heat-sealing film in which both sides of a high melting point resin layer to be an intermediate layer are sandwiched between low melting point resin layers (thermoplastic resin layers). Further, examples of the elastomer material include polyester-based thermoplastic elastomers.

[Diagonal placement of current collection tabs]
For example, as shown in FIGS. 2 (a) to 2 (c), particularly in FIG. 2 (c), the electrode assembly 11 of the secondary battery according to the embodiment of the present invention has two current collecting tabs (13a, 13b). Each extends "diagonally". Specifically, the "positive electrode current collecting tab 13a _{" and "positive electrode current collecting tab 13a" so that the "extending direction X a} _{of the positive electrode current collecting tab 13a" and the "extending direction X b} of the negative electrode current collecting tab 13b" form an "angle θ". The negative electrode current collecting tabs 13b ”are arranged“ diagonally ”(for example, FIG. 2B).

_{The “angle θ” of the angle formed by the “extending direction X a} of the positive electrode current collecting tab 13a _{” and the “extending direction X b} of the negative electrode current collecting tab 13b” is, for example, 15 ° or more and 120 ° or less, preferably 25 ° or more. It is 105 ° or less, more preferably 57 ° or more and 105 ° or less, and even more preferably 57 ° or more and 102 ° or less. Within the above range, values such as "tab width", "tab length" and / or "electrode area" described below can be further appropriately improved. In addition, the degree of freedom in tab design can be further increased.

In the secondary battery according to the embodiment of the present invention, each of the positive electrode current collecting tab 13a and the negative electrode current collecting tab 13b, which can be arranged diagonally, may have an arbitrary geometric shape and are shown in the figure. It is not limited to a rectangle such as a rectangle or a square or a shape such as a substantially rectangular shape as in the embodiment.

It is preferable that the positive electrode current collecting tab 13a and the negative electrode current collecting tab 13b have a rectangular shape (for example, a rectangle, a square, etc.) or a substantially rectangular shape, respectively. If the plan view shape of the current collecting tab is rectangular, the design and manufacture of the current collecting tab becomes simpler. The shapes of the positive electrode current collecting tab 13a and the negative electrode current collecting tab 13b may be the same or different in plan view, but they are preferably the same shape. The dimensions of the positive electrode current collecting tab 13a and the negative electrode current collecting tab 13b may be the same or different, but are preferably the same.

For example, when the current collection tab (positive electrode current collection tab 13a and / or negative electrode current collection tab 13b) has a rectangular shape in a plan view, the current collection tab with respect to the circular diameter D of the main body (or electrode main body) of the electrode assembly. Ratio of length W in the width direction (hereinafter, may be referred to as "tab width (W)") (tab width W / diameter D, that is, the ratio of "W / D") (for example, the positive electrode collection shown in FIG. Tab width W _a / diameter D of the _{electrical tab 13a (ie, the ratio of "W a} / D") and / or tab width W _b / diameter D of the _{negative electrode current collector tab 13 b (ie, the ratio of "W b} / D")) Is, for example, 0.1 or more and 0.45 or less, preferably 0.3 or more and 0.45 or less. Here, the tab widths W _a and W _b may be the same or different, but are preferably the same.
The above ratio (W / D, in particular W _{a /} D and / or W _{b /} D) When is within the above range, while avoiding the area of the electrode body is remarkably reduced, the current collecting tabs The area of the plan view shape can be further increased. In addition, the degree of freedom in tab design can be further improved.

Alternatively, when the plan view shape of the current collecting tabs (positive electrode current collecting tab 13a and / or negative electrode current collecting tab 13b) is rectangular, the current collecting tab with respect to the circular diameter D of the main body (or electrode main body) of the electrode assembly. the ratio of the width direction length W (tab width (W)) (tab width W / diameter D, i.e. "W / D" ratio) (e.g., tab width of the positive electrode current collector tabs 13a shown in FIG. 3 W _a / The diameter D (that is, _{the ratio of “W a} / D”) and / or the tab width W _b / diameter D (that _{is, the ratio of “W b} / D”) of the negative electrode current collecting tab 13b) is preferably, for example, 0.3 or more. Is 0.3 or more and 0.5 or less. Here, the tab widths W _a and W _b may be the same or different, but are preferably the same.
The above ratio (W / D, in particular W _{a /} D and / or W _{b /} D) When is within the above range, while avoiding the area of the electrode body is remarkably reduced, the current collecting tabs The area of the plan view shape can be increased. In addition, the degree of freedom in tab design can be improved.

For example, when the plan view shape of the current collecting tab (positive electrode current collecting tab 13a and / or negative electrode current collecting tab 13b) is rectangular, the current collecting tab with respect to the circular diameter D of the main body (or electrode main body) of the electrode assembly. Ratio of length L in the extending direction (hereinafter, may be referred to as "tab length (L)") (tab length L / diameter D, that is, "L / D" ratio) (for example, the positive electrode shown in FIG. tab length _{L a} / the diameter D of the current collector tabs 13a tab length (i.e., _"L a / D" ratio) and / or the negative electrode current collector tab 13b _{L b} / diameter D (i.e. the ratio of the _"L b / D") ) Is, for example, 0.1 or more and 0.2 or less, preferably 0.1 or 0.2. Here tab length L _a and L _b may be different even in the same, but are preferably the same.
When the above ratio (L / D, specifically _La / D and / or L _b / D) is within the above range, the current collecting tab of the current collecting tab avoids a significant decrease in the area of the electrode body. The area of the plan view shape can be further increased. In addition, the degree of freedom in tab design can be further improved.

In the secondary battery of the present disclosure, it is preferable that the electrodes of the electrode assembly include a positive electrode and a negative electrode capable of occluding and releasing lithium ions.

Hereinafter, in the electrode assembly of the secondary battery according to the embodiment of the present invention, the “positive electrode current collecting tab” and the “negative electrode current collecting tab” are arranged “diagonally”, respectively (for example, FIG. 2 (c)). ) And Comparative Examples 1 and 2 in which the two current collecting tabs are arranged facing each other or in parallel (for example, the conventional configuration shown in FIGS. 8A and 8B) will be described. do. The present invention is not limited to the following examples.

Comparative Example 1
The electrode assembly 21 shown in FIG. 4 (a) was prepared. In the electrode assembly 21, two current collecting tabs (positive electrode current collecting tab 23a and negative electrode current collecting tab 23b) are arranged so as to extend in opposite directions.
More specifically, as shown in FIG. 8A, the main body (and the electrode main body) of the electrode assembly 21 has a shape (

notches

22a and 22b) in which a part thereof is cut out vertically from a circle having a diameter of 10 mm. It has a circular shape in a plan view. The positive electrode current collecting tab 23a and the negative electrode current collecting tab 23b have the same plan-view shape.

Comparative Example 2
The electrode assembly 31 shown in FIG. 4B was prepared. In the electrode assembly 31, two current collecting tabs (positive electrode current collecting tab 33a and negative electrode current collecting tab 33b) are arranged side by side so as to extend in the same direction.
More specifically, as shown in FIG. 8B, the main body (and the electrode main body) of the electrode assembly 31 is a circular plane (a circle having a notch 32) cut out from a circle having a diameter of 10 mm. It has a visual shape. The positive electrode current collecting tab 33a and the negative electrode current collecting tab 33b have the same plan-view shape.

Example 1
The electrode assembly 11 shown in FIG. 4C was prepared. In the electrode assembly 11, for example, as shown in FIG. 2B, the “angle θ” of the angle formed by the “ _{extending direction X a} of the positive electrode current collecting tab 13a” and the “extending direction X _{b of the negative electrode current collecting tab 13b” is formed.} Is within the range of "15 ° or more and 120 ° or less". The “positive electrode current collecting tab 13a” and the “negative electrode current collecting tab 13b” are relatively arranged so as to extend “diagonally”, respectively.
The main body (and the electrode main body) of the electrode assembly 11 has a circular plan view shape (a circle having a notch 12 having two sides m and n) cut out from a circle having a diameter of 10 mm (FIG. FIG. 2 (a)).
The positive electrode current collecting tab 13a and the negative electrode current collecting tab 13b have the same plan-view shape.

The tab dimensions (tab width, tab length and tab area) were changed in "Comparative Example 1", "Comparative Example 2" and "Example 1" according to "Conditions 1 to 10" shown in Table 1 below.

The "electrode area" (area in plan view of the main body of the electrode assembly) (mm ² ) of each electrode assembly measured under "conditions 1 to 10" shown in Table 1 is shown in the graphs of Table 2 and FIG. 5 below. show.

The following was found from the graphs in Table 2 and FIG.

-Comparison between Example 1 and Comparative Example 1 When Example 1 and Comparative Example 1 were compared, it was found that the electrode area of Example 1 was larger than that of Comparative Example 1 under all of the conditions 1 to 10. ..
-Comparison between Example 1 and Comparative Example 2 When Example 1 and Comparative Example 2 were compared, the electrode areas were about the same under conditions 1 to 4, but under conditions 5 to 10, the electrode area was similar to that of Example 1. It was found that the electrode area was larger than that of Comparative Example 2. In particular, in Example 1, it was found that the tendency became remarkable as the angle θ and the tab width increased.

Next, regarding "conditions 1 to 10", the "tab length" was divided into "1 mm" and "2 mm", and the relationship between the "tab area" and the "electrode area change rate" was examined and considered.
Here, the "electrode area change rate" (slope of the curve) is an index showing that the degree of freedom in tab design increases when the value is small, and can be expressed by the following equation.
[Electrode area change rate] = [Electrode area change amount] / [Tab area change amount]
[In the formula, the "electrode area change amount" is the change amount of the electrode area before and after each condition shown in the table below, and the "tab area change amount" is the change amount before and after each condition shown in the following table. The amount of change in the tab area. ]

The results when the "tab length" is "1 mm" are shown in the graphs of Table 3 and FIG. 6 below.

The following was found from the graphs in Table 3 and FIG.

-Comparison between Example 1 and Comparative Example 1 Comparing Example 1 and Comparative Example 1, there is a large difference in the degree of freedom (electrode area change rate) of tab design between Example 1 and Comparative Example 1 under any condition. It turned out that there was no. Therefore, in Example 1 of the present invention, it was surprisingly found that a tab length of 1 mm has the same degree of freedom in tab design as Comparative Example 1 (see FIG. 4A).
-Comparison between Example 1 and Comparative Example 2 Comparing Example 1 and Comparative Example 2, the electrode area change rate of Example 1 was much smaller than that of Comparative Example 2 under any of the conditions, and the tabs were tabbed. It was found that the degree of freedom in design was remarkably large.

The results when the "tab length" is "2 mm" are shown in the graphs of Table 4 and FIG. 7 below.

The following was found from the graphs in Table 4 and FIG.

-Comparison between Example 1 and Comparative Example 1 Comparing Example 1 and Comparative Example 1, there is a large difference in the degree of freedom (electrode area change rate) of tab design between Example 1 and Comparative Example 1 under any condition. It turned out that there was no. Therefore, in Example 1 of the present invention, it was surprisingly found that even with a tab length of 2 mm, the degree of freedom in tab design is comparable to that of Comparative Example 1 (see FIG. 4A).
-Comparison between Example 1 and Comparative Example 2 Comparing Example 1 and Comparative Example 2, the value of the electrode area change rate in Example 1 was much smaller than that in Comparative Example 2 under all conditions. It was found that the degree of freedom in tab design is remarkably large.

From the above comparison, especially from the results of Table 2 (FIG. 5), in "Example 1" of the present invention, the "diagonal arrangement" of the current collection tab, specifically, the "angle θ" is set to "15 ° or more and 120 ° or less". By setting within the range of "Comparative Example 1", the "electrode area" can be increased over the entire area (Conditions 1 to 10), and the "Tab width" is also set for "Comparative Example 2". , It was found that the "electrode area" can be increased as the "tab area" increases (particularly conditions 5 to 10).
Further, from the results of Table 3 (FIG. 6) and Table 4 (FIG. 7), it was found that there is no great difference in the degree of freedom of tab design between "Example 1" and "Comparative Example 1". Then, it was found that "Example 1" was remarkably superior to "Comparative Example 2" in the degree of freedom in tab design.

Although the embodiments of the present invention have been described above with reference to the examples, they are merely examples of typical examples. Therefore, those skilled in the art will easily understand that the present invention is not limited to this, and various aspects are conceivable.

For example, in the above embodiment, the secondary battery having a circular button shape (coin shape) in a plan view is mainly mentioned, but the present invention is not necessarily limited to the above embodiment. That is, the secondary battery of the present disclosure is not limited to a circular shape in a plan view, and may have any other geometric shape.

The secondary battery according to the embodiment of the present invention can be used in various fields where battery use or storage can be expected. Although only an example, the secondary battery according to the embodiment of the present invention includes electric / information / communication fields (for example, mobile phones, smartphones, laptop computers and digital cameras, activities) in which electric / electronic devices can be used. Electric / electronic equipment field or mobile equipment field including meter, arm computer, electronic paper, wearable device, RFID tag, card type electronic money, small electronic device such as smart watch), home / small industrial application (for example, electric) Tools, golf carts, home / nursing / industrial robots), large industrial applications (eg forklifts, elevators, bay port cranes), transportation systems (eg hybrids, electrics, buses, trains) , Electric assisted bicycles, electric motorcycles, etc.), power system applications (for example, various power generation, road conditioners, smart grids, general household installation type power storage systems, etc.), medical applications (medical equipment fields such as earphone hearing aids) , Pharmaceutical applications (fields such as dose management systems), IoT fields, space / deep sea applications (for example, fields such as space probes and submersible research vessels) and the like.

1 Positive electrode 2 Negative electrode 3 Separator 5 Electrode constituent layer (or electrode constituent unit)
10,11,21,31 Electrode assembly (or electrode)
12, 22, 32 Notch 13, 23, 33 Current collector tab

Claims

A secondary battery having an electrode assembly, in which a positive electrode current collecting tab and a negative electrode current collecting tab extend diagonally from the electrode assembly.
The secondary battery according to claim 1, wherein the angle formed by the extending direction of the positive electrode current collecting tab extending diagonally and the extending direction of the negative electrode current collecting tab is 15 ° or more and 120 ° or less. ..
The secondary battery according to claim 2, wherein the angle is 25 ° or more and 105 ° or less.
The secondary battery according to any one of claims 1 to 3, wherein the main bodies of the positive electrode and the negative electrode included in the electrode assembly have a circular plan view shape in which a part thereof is cut out.
The secondary battery according to claim 4, wherein the positive electrode current collecting tab and the negative electrode current collecting tab are positioned in the virtual circle before the notch in the notched circular view in a plan view.
The secondary battery according to claim 4 or 5, wherein the contour of the cutout portion is composed of at least two sides in a plan view.
The secondary battery according to claim 6, wherein the angle between the two sides is less than 180 °.
The positive electrode current collecting tab and the negative electrode current collecting tab each have a rectangular plan view shape, and the length in the width direction of the positive electrode current collecting tab and / or the negative electrode current collecting tab with respect to the circular diameter of the main body. The secondary battery according to any one of claims 4 to 7, wherein the ratio of the above is 0.1 or more and 0.45 or less.
The positive electrode current collecting tab and the negative electrode current collecting tab each have a rectangular plan view shape, and the length in the width direction of the positive electrode current collecting tab and / or the negative electrode current collecting tab with respect to the circular diameter of the main body. The secondary battery according to any one of claims 4 to 8, wherein the ratio of the above is 0.3 or more.
The positive electrode current collecting tab and the negative electrode current collecting tab each have a rectangular plan view shape, and the length of the positive electrode current collecting tab and / or the negative electrode current collecting tab in the extending direction with respect to the circular diameter of the main body. The secondary battery according to any one of claims 4 to 9, wherein the ratio of the electrodes is 0.1 or more and 0.2 or less.
The secondary battery according to any one of claims 1 to 10, wherein the electrode assembly has a mirror image symmetrical shape in a plan view.
The secondary battery according to any one of claims 1 to 11, wherein the electrode of the electrode assembly includes a positive electrode and a negative electrode capable of storing and releasing lithium ions.