Secondary battery

Abstract

This secondary battery comprises: an insulating film that is a porous body, and has a first main surface and a second main surface on the reverse side from the first main surface; a positive electrode current collector that is a porous body and is provided on the first main surface of the insulating film; a positive electrode active material layer that is provided on the positive electrode current collector; a negative electrode current collector that is a porous body and is provided on the second main surface of the insulating film; and a negative electrode active material layer that is provided on the negative electrode current collector. At least one of the positive electrode current collector and the negative electrode current collector includes a first current collector protrusion, the insulating film includes an insulating film protrusion that is laminated on the first current collector protrusion, the laminated insulating film protrusion and the first current collector protrusion are bent in a U-shape, the first current collector protrusion is provided so as to cover an outer main surface of the insulating film protrusion, and the first current collector protrusion and an external terminal are electrically connected.

Description

secondary battery

[0001] This invention relates to a secondary battery.

[0002] Non-patent documents 1 and 2 describe that increasing the thickness of the electrodes of a secondary battery increases the proportion of active material in the battery, thereby improving battery capacity and energy density.

[0003] Yudi Kuang, Chaoji Chen, Dylan Kirsch, Liangbing Hu, Thick Electrode Batteries: Principles, Opportunities, and Challenges, Advanced Energy Materials 9, 1901457 (2019).Christian Heubner, Michael Schneider, Alexander Michaelis, Diffusion-Limited C-Rate: A Fundamental Principle Quantifying the Intrinsic Limits of Li-Ion Batteries, Advanced Energy Materials 10, 1902523 (2020).

[0004] Increasing the thickness of the electrodes in a secondary battery can lengthen the diffusion distance of carrier ions, potentially making it difficult to pass large currents. This could also lead to a decrease in charge-discharge characteristics at high current rates.

[0005] On the other hand, if the electrodes of the secondary battery are made thinner, it is preferable to also make the film thickness of the current collector thinner. This may make it difficult to connect the current collector to the external terminals.

[0006] The present invention aims to provide a secondary battery that can properly connect a current collector and external terminals.

[0007] A secondary battery according to one embodiment comprises an insulating film which is a porous material and has a first main surface and a second main surface opposite to the first main surface, a positive electrode current collector which is a porous material provided on the first main surface of the insulating film, a positive electrode active material layer provided on the positive electrode current collector, a negative electrode current collector which is a porous material provided on the second main surface of the insulating film, and a negative electrode active material layer provided on the negative electrode current collector, wherein the electrode body which is formed by laminating the positive electrode active material layer, the positive electrode current collector, the insulating film, the negative electrode current collector and the negative electrode active material layer is wound, and the positive electrode current collector The negative electrode current collector includes a first current collector projection that protrudes from at least one side surface of the positive electrode active material layer and the negative electrode active material layer, and the insulating film includes an insulating film projection that protrudes from at least one side surface of the positive electrode active material layer and the negative electrode active material layer and is laminated with the first current collector projection, and the laminated insulating film projection and the first current collector projection are bent into a U shape so that the first current collector projection covers the outer main surface of the insulating film projection, and the first current collector projection is electrically connected to an external terminal.

[0008] According to the secondary battery of the present invention, the current collector and the external terminals can be connected smoothly.

[0009] Figure 1 is a cross-sectional view showing an example of a secondary battery according to the first embodiment. Figure 2 is an enlarged cross-sectional view showing a part of the cross-section of the electrode body according to the first embodiment. Figure 3 is an enlarged cross-sectional view showing the current collector assembly according to the first embodiment. Figure 4 is a schematic cross-sectional view showing the connection configuration between the current collector and the external terminal of the secondary battery according to the first embodiment. Figure 5 is an explanatory diagram for illustrating an example of a method for bending the current collector assembly. Figure 6 is a schematic cross-sectional view showing the connection configuration between the current collector and the external terminal of the secondary battery according to the second embodiment. Figure 7 is a schematic cross-sectional view showing the connection configuration between the current collector and the external terminal of the secondary battery according to the first modified example. Figure 8 is a schematic cross-sectional view showing the electrode body (current collector assembly) according to the second modified example. Figure 9 is a schematic cross-sectional view showing the connection configuration between the electrode body (current collector assembly), the external terminal and the housing of the secondary battery according to the third modified example. Figure 10 is a schematic cross-sectional view showing the connection configuration between the electrode body (current collector assembly), the external terminal and the housing of the secondary battery according to the fourth modified example. Figure 11 is an explanatory diagram illustrating the configuration of a current collector assembly according to the fifth modified example.

[0010] Embodiments of the present disclosure will be described in detail below with reference to the drawings. However, these embodiments do not limit the present disclosure. Each embodiment described in this disclosure is illustrative, and partial substitution or combination of configurations is possible between different embodiments. In modifications and subsequent embodiments, descriptions of matters common to the first embodiment will be omitted, and only the differences will be described. In particular, similar effects and benefits due to similar configurations will not be mentioned sequentially for each embodiment.

[0011] (First Embodiment) Figure 1 is a cross-sectional view showing an example of a secondary battery according to the first embodiment. As shown in Figure 1, the secondary battery 1 according to the first embodiment is a wound-type lithium-ion secondary battery in which an electrode body 10 is wound. The secondary battery 1 comprises an electrode body 10, conductive members 14, 15 and a housing 20.

[0012] The electrode body 10 comprises a current collector assembly 210, a positive electrode active material layer 220, and a negative electrode active material layer 230. In this embodiment, the electrode body 10 is laminated such that the negative electrode active material layer 230 is arranged on the inner circumference side and the positive electrode active material layer 220 is arranged on the outer circumference side. The electrode body 10 is also wound via a separator 240. The detailed configuration of the electrode body 10 and the current collector assembly 210 will be described later in Figure 2 and subsequent figures.

[0013] As shown in Figure 1, the housing 20 comprises a main body portion 21 and a lid portion 22. The materials of the main body portion 21 and the lid portion 22 are conductive. The materials of the main body portion 21 and the lid portion 22 are, for example, iron, stainless steel, aluminum, etc.

[0014] The main body portion 21 is cylindrical with an opening 21a at one end. A conductive member 15 (for example, an external negative electrode terminal) is electrically connected to the inner surface of the main body portion 21.

[0015] The lid portion 22 covers the opening 21a of the main body portion 21. The lid portion 22 is placed on the main body portion 21 in a state of electrical insulation from the main body portion 21. A conductive member 14 (for example, an external positive terminal) is electrically connected to the lid portion 22.

[0016] Next, the configuration of the electrode body 10 will be described in detail with reference to Figures 2 and 3. Figure 2 is an enlarged cross-sectional view showing a part of the cross-section of the electrode body according to the first embodiment. More specifically, Figure 2 shows a two-layer electrode body 10 among the wound electrode body 10.

[0017] As shown in Figure 2, in the secondary battery 1, the electrode body 10 has a structure in which a positive electrode active material layer 220, a current collector assembly 210, and a negative electrode active material layer 230 are stacked in the order from the inner circumference to the outer circumference. The positive electrode active material layer 220 and the negative electrode active material layer 230 contained in the electrode body 10 are layered members for the charge and discharge reaction of the secondary battery 1 according to the first embodiment. In the following description, one of the thickness directions of the electrode body 10 may be described as the Z1 direction (outer circumference side), and the other thickness direction of the electrode body 10 may be described as the Z2 direction (inner circumference side). Note that the stacking order of the electrode body 10 and the current collector assembly 210 shown in Figures 2 and 3 is merely an example, and the stacking order may be inverted.

[0018] Note that, although FIG. 2 shows a configuration in which the electrode body 10 is wound two turns, the number of windings of the electrode body 10 is not limited to two turns, and the electrode body 10 may be wound three or more turns. The separator 240 is disposed on the outer peripheral side or the inner peripheral side of the electrode body 10 and is wound together with the electrode body 10. Further, an insulating layer different from the separator 240 may be provided on the outer peripheral side of the wound electrode body 10.

[0019] FIG. 3 is an enlarged cross-sectional view showing the current collector assembly according to the first embodiment. As shown in FIG. 3, the current collector assembly 210 includes an insulating film 211, a positive electrode current collector 212, and a negative electrode current collector 213.

[0020] The insulating film 211 is an insulating film. In the present disclosure, the term "insulating" means that the electrical conductivity is 10 －６ S / m or less. This can suppress short-circuiting between the positive electrode current collector 212 and the negative electrode current collector 213. The insulating film 211 is a porous body. In the present disclosure, the term "porous body" refers to a material having a porosity of 10% or more. This allows carrier ions of the secondary battery 1, such as lithium ions, to pass through the insulating film 211 in the thickness direction.

[0021] The porosity of the insulating film 211 is preferably 30% or more. This can improve the Li ion conductivity of the insulating film 211. The porosity of the insulating film 211 is preferably 70% or less. This can increase the strength of the insulating film 211. The porosity of the insulating film 211 is more preferably 40% or more and 60% or less. This can improve the Li ion conductivity of the insulating film 211 and increase the strength, thereby achieving both the electrochemical stability and mechanical properties of the secondary battery 1.

[0022] The average pore diameter of the insulating film 211 is preferably 10 nm or more and 50 μm or less, and the insulating film 211 is more preferably a nanoporous material. Here, the term "nanoporous material" refers to a material whose average pore diameter is in the range of mesopores, that is, in the range of 10 nm or more and 50 nm or less. This provides excellent lithium ion permeability.

[0023] The insulating film 211 includes, for example, a polymer material. Preferably, the insulating film 211 contains at least one of polyolefins, polyimides, polyamides, polyesters, cellulose, glass, and metal oxides, and is particularly preferably poly(p-phenylene terephthalamide). Here, an example of an insulating film 211 containing glass is glass filter paper such as ADVANTEC's GC-50. Another example of an insulating film 211 containing a metal oxide is a porous alumina film. This makes it possible to increase the strength of the insulating film 211 and achieve both electrochemical stability and good mechanical properties of the secondary battery 1.

[0024] In this disclosure, the average pore diameter refers to the value 4V / A, which is obtained by dividing the total pore volume V, calculated by the BJH method from pore analysis obtained by the gas adsorption method, by the specific surface area A and multiplying by four. In this disclosure, the porosity refers to the ratio of the total pore volume V to the bulk volume, and can be calculated as: porosity (%) = total pore volume V / bulk volume × 100. The bulk volume can be calculated, for example, based on dimensions such as thickness or area.

[0025] The insulating film 211 has a first main surface 211a and a second main surface 211b opposite to the first main surface 211a. The positive electrode current collector 212 is laminated on the first main surface 211a, which is the surface of the insulating film 211 in the Z2 direction.

[0026] The positive electrode current collector 212 is a porous body. The positive electrode current collector 212 has a positive electrode porous body 212a and a positive electrode conductive layer 212b. The positive electrode porous body 212a is a porous body laminated on the first main surface 211a of the insulating film 211. Preferably, the average pore diameter of the positive electrode porous body 212a is 10 nm or more. This ensures excellent lithium ion permeability even when the positive electrode conductive layer 212b is formed within the pores of the positive electrode porous body 212a. Furthermore, it is more preferable that the average pore diameter of the positive electrode porous body 212a is 1 μm or more. This prevents the pores of the positive electrode porous body 212a from being blocked by the positive electrode conductive layer 212b, even when a positive electrode conductive layer 212b of sufficient thickness is used to obtain sufficient conductivity.

[0027] The positive electrode porous body 212a preferably contains at least one of polyolefins, polyimides, polyamides, polyesters, cellulose, glass, and metal oxides, and for example, it contains polymers such as polyimide and poly(vinylidene-co-hexafluoropropene). In this disclosure, polyimide refers to a polymer containing imide bonds. An example of a positive electrode porous body 212a containing glass is, for example, glass filter paper such as ADVANTEC's GC-50. An example of a positive electrode porous body 212a containing a metal oxide is a porous alumina film. This makes it possible to increase the strength of the positive electrode porous body 212a and achieve both electrochemical stability and good mechanical properties of the secondary battery 1.

[0028] The positive electrode conductive layer 212b is a conductive coating that covers the surface of the pores of the positive electrode porous body 212a. In this disclosure, conductivity means that the electrical conductivity is 10 ４ This refers to being made of a material with a density of S / m or greater. The positive electrode conductive layer 212b includes a conductor such as aluminum or stainless steel.

[0029] The thickness of the positive electrode conductive layer 212b is preferably 100 nm or more, and more preferably 1 μm or more. This improves electrical conductivity and reduces the internal resistance of the secondary battery 1. The thickness of the positive electrode conductive layer 212b is preferably 10 μm or less, and more preferably 2 μm or less. This prevents the pores of the positive electrode porous body 212a from being blocked by the positive electrode conductive layer 212b and improves the permeability of the electrolyte. Here, the thickness of the positive electrode conductive layer 212b refers to the average thickness of the positive electrode conductive layer 212b along the normal direction of the surface of the pores of the positive electrode porous body 212a. The thickness of the positive electrode conductive layer 212b can be measured with a scanning electron microscope.

[0030] The negative electrode current collector 213 is a porous material. The negative electrode current collector 213 has a negative electrode porous material 213a and a negative electrode conductive layer 213b. The negative electrode current collector 213 is laminated on the second main surface 211b, which is the surface in the Z1 direction of the insulating film 211.

[0031] The negative electrode porous body 213a is a porous body laminated on the second main surface 211b of the insulating film 211. Preferably, the average pore diameter of the negative electrode porous body 213a is 10 nm or more. This ensures excellent lithium ion permeability even when the negative electrode conductive layer 213b is formed within the pores of the negative electrode porous body 213a. Furthermore, preferably, the average pore diameter of the negative electrode porous body 213a is 1 μm or more. This prevents the pores of the negative electrode porous body 213a from being blocked by the negative electrode conductive layer 213b, even when a negative electrode conductive layer 213b of sufficient thickness is used to obtain sufficient conductivity.

[0032] The negative electrode porous body 213a preferably contains at least one of polyolefins, polyimides, polyamides, polyesters, cellulose, glass, and metal oxides, and for example, it contains polymers such as polyimide and poly(vinylidene-co-hexafluoropropene). Here, an example of a negative electrode porous body 213a containing glass is glass filter paper such as ADVANTEC's GC-50. An example of a negative electrode porous body 213a containing a metal oxide is a porous alumina film. This makes it possible to increase the strength of the negative electrode porous body 213a and achieve both electrochemical stability and good mechanical properties of the secondary battery 1.

[0033] The negative electrode conductive layer 213b is a conductive coating that covers the surface of the pores of the negative electrode porous body 213a. The negative electrode conductive layer 213b contains a conductor such as copper or stainless steel. The thickness of the negative electrode conductive layer 213b is preferably 100 nm or more, and more preferably 1 μm or more. This improves electrical conductivity and reduces the internal resistance of the secondary battery 1. The thickness of the negative electrode conductive layer 213b is preferably 10 μm or less, and more preferably 2 μm or less. This prevents the pores of the negative electrode porous body 213a from being blocked by the negative electrode conductive layer 213b and improves the permeability of the electrolyte. Here, the thickness of the negative electrode conductive layer 213b refers to the average thickness of the negative electrode conductive layer 213b along the normal direction to the surface of the pores of the negative electrode porous body 213a. The thickness of the negative electrode porous body 213a can be measured with a scanning electron microscope.

[0034] As shown in Figure 2, the positive electrode active material layer 220 contains one or more types of positive electrode active materials capable of inserting and extracting lithium. However, the positive electrode active material layer 220 may further contain one or more types of other materials such as a positive electrode binder and a positive electrode conductive agent. The method for forming the positive electrode active material layer 220 is not particularly limited, and specifically, a coating method or the like may be used.

[0035] The type of the positive electrode active material is not particularly limited, and specifically, it is a lithium-containing compound or the like. The lithium-containing compound is a compound containing lithium and one or more transition metal elements as constituent elements. The lithium-containing compound may further contain one or more other elements as constituent elements. The type of the other element is not particularly limited as long as it is an element other than lithium and the transition metal element, and specific examples thereof include elements belonging to any one of Groups 2 to 15 in the long-period periodic table.

[0036] The type of the lithium-containing compound is not particularly limited, and specific examples of the lithium-containing compound include oxides, phosphate compounds, silicate compounds, borate compounds, and the like. Specific examples of the oxide include LiNiO ２ , LiCoO ２ , LiCo ０．９８ Al ０．０１ Mg ０．０１ O ２ , LiNi ０．５ Co ０．２ Mn ０．３ O ２ , LiNi ０．８ Co ０．１５ Al ０．０５ O ２ , LiNi ０．３３ Co ０．３３ Mn ０．３３ O ２ , Li １．２ Mn ０．５２ Co ０．１７５ Ni ０．１ O ２ , Li １．１５ Mn ０．６５ Ni ０．２２ Co ０．１３ O ２ and LiMn ２ O ４ and the like. Specific examples of the phosphate compound include LiFePO ４LiMnPO ４ LiFe ０．５ Mn ０．５ PO ４ and LiFe ０．３ Mn ０．７ PO ４ And so on.

[0037] The positive electrode binder contains one or more types of synthetic rubber and polymer compounds. Specific examples of synthetic rubber include styrene-butadiene rubber, fluorine-based rubber, and ethylene-propylenediene. Specific examples of polymer compounds include polyvinylidene fluoride, polyimide, and carboxymethylcellulose.

[0038] The positive electrode conductive agent contains one or more conductive materials, such as carbon materials. Specific examples of carbon materials include graphite, carbon black, acetylene black, and Ketjenblack. However, the conductive material may also be a metallic material or a polymer compound.

[0039] The negative electrode active material layer 230 contains one or more negative electrode active materials capable of intercalating and deintercalating lithium. However, the negative electrode active material layer 230 may further contain one or more other materials such as a negative electrode binder and a negative electrode conductive agent. The method for forming the negative electrode active material layer 230 is not particularly limited and may be one or more of the following: coating, gas phase, liquid phase, thermal spraying, and firing (sintering).

[0040] The negative electrode active material contains lithium metal. The type of negative electrode active material is not particularly limited, and specifically, it may be one or both of carbon materials and metallic materials. This allows for a high energy density to be obtained. Specific examples of carbon materials include easily graphitizable carbon, poorly graphitizable carbon, and graphite such as natural graphite and artificial graphite. Metallic materials are materials that contain elements capable of forming alloys with lithium, and which are either metallic elements or metalloid elements, with specific examples being silicon and tin. Metallic materials may be one or more of elements, alloys, and compounds, or they may be mixtures or materials containing two or more phases. A specific example of a metallic material is TiSi ２ and SiO ｘ (e.g., 0 < x ≤ 2).

[0041] The negative electrode binder can be made from the same material as the positive electrode binder. Similarly, the negative electrode conductive agent can be made from the same material as the positive electrode conductive agent.

[0042] The separator 240 is a film that insulates the positive electrode active material layer 220 and the negative electrode active material layer 230. The separator 240 is provided between the main surface of the positive electrode active material layer 220 and the main surface of the negative electrode active material layer 230 in the wound electrode body 10 so that the positive electrode active material layer 220 and the negative electrode active material layer 230 do not come into direct contact.

[0043] The material of the separator 240 is preferably electrically stable, chemically stable with respect to the positive electrode active material, negative electrode active material, and electrolyte, and also insulating. The separator 240 can be, for example, a layer containing at least one of a polymer nonwoven fabric, a porous film, and glass and ceramic fibers. The material of the separator 240 is more preferably a porous polyolefin film. This improves the safety of the battery by providing short-circuit prevention and shutdown effects.

[0044] Note that the separator 240 is not an essential component. The separator 240 may be replaced, for example, with the current collector assembly 210.

[0045] The electrolyte is impregnated into the insulating film 211 and the separator 240. In the example shown in Figure 1, the electrolyte is filled into the space enclosed by the main body 21 and the lid 22. The electrolyte is a non-aqueous electrolyte containing an electrolyte salt and a solvent that dissolves this electrolyte salt.

[0046] Electrolyte salts include, for example, lithium perchlorate (LiClO2). ４ ), lithium hexafluoride phosphate (LiPF) ６ ), lithium tetrafluoroborate (LiBF ４ ), lithium bis(trifluoromethanesulfonyl)imide (LiN(SO) ２ CF ３ ) ２ ), lithium bis(pentafluoroethanesulfonyl)imide (LiN(SO) ２ C ２ F ５ )２ ), lithium hexafluoroarsenate (LiAsF ６ Contains lithium salts such as ).

[0047] The solvents include, for example, lactone-based solvents such as γ-butyrolactone, γ-valerolactone, δ-valerolactone, and ε-caprolactone; carbonate ester-based solvents such as ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, dimethyl carbonate, ethylmethyl carbonate, and diethyl carbonate; ether-based solvents such as 1,2-dimethoxyethane, 1-ethoxy-2-methoxyethane, 1,2-diethoxyethane, tetrahydrofuran, and 2-methyltetrahydrofuran; nitrile-based solvents such as acetonitrile; sulforane-based solvents; phosphoric acids; phosphoric acid ester solvents; and non-aqueous solvents including pyrrolidones.

[0048] The electrolyte preferably contains at least one additive from among fluorinated carboxylic acid esters, sulfonic acid esters, sulfonic acid anhydrides, and carboxylic acid anhydrides. This promotes the formation of low-resistance SEI (Solid Electrolyte Interphase), thereby improving the charging load characteristics. Examples of fluorinated carboxylic acid esters include fluoroethylene carbonate (FEC). Examples of sulfonic acid anhydrides include propanedisulfonic acid anhydride (PSAH). Examples of sulfonic acid esters include 1,3-propanesultone. Examples of carboxylic acid anhydrides include 1,4-dioxan-2,6-dione.

[0049] Next, with reference to Figures 4 and 5, the connection configuration between the positive electrode current collector 212 and the negative electrode current collector 213 and the external terminals (conductive members 14 and 15) will be described. Figure 4 is a schematic cross-sectional view showing the connection configuration between the current collectors and the external terminals of a secondary battery according to the first embodiment.

[0050] As shown in Figure 4, the wound electrode body 10 has a first connection portion 215 electrically connected to a conductive member 14 (external positive electrode terminal) and a second connection portion 216 electrically connected to a conductive member 15 (external negative electrode terminal). The first connection portion 215 and the second connection portion 216 are provided on opposite sides of the wound electrode body 10 in the direction along the winding central axis C. The first connection portion 215 and the second connection portion 216 are each formed by bending a part of the current collector assembly 210 into a U shape and are provided at an inclination toward the inner or outer circumference with respect to the direction along the winding central axis C. The first connection portion 215 and the second connection portion 216 can be selectively inclined toward the inner or outer circumference with respect to the direction along the winding central axis C by forming a part of the current collector assembly 210 into a U shape.

[0051] More specifically, as described above, the electrode body 10 includes an insulating film 211, a positive electrode current collector 212 which is a porous material provided on the first main surface 211a of the insulating film 211, a positive electrode active material layer 220 provided on the positive electrode current collector 212, a negative electrode current collector 213 which is a porous material provided on the second main surface 211b of the insulating film 211, and a negative electrode active material layer 230 provided on the negative electrode current collector 213.

[0052] The positive electrode current collector 212 includes a positive electrode current collector main portion 212s and a first positive electrode current collector projection 212t. The positive electrode current collector main portion 212s is positioned between the first main surface 211a of the insulating film 211 and the positive electrode active material layer 220. The first positive electrode current collector projection 212t is formed continuously with the positive electrode current collector main portion 212s and protrudes from the sides of the positive electrode active material layer 220 and the negative electrode active material layer 230. In other words, of the positive electrode current collector 212, the positive electrode current collector main portion 212s is the portion that overlaps with the positive electrode active material layer 220, and the first positive electrode current collector projection 212t is the portion that does not overlap with the positive electrode active material layer 220.

[0053] The first positive electrode current collector projection 212t is formed of the same material as the positive electrode current collector main portion 212s and is provided continuously and integrally. That is, both the positive electrode current collector main portion 212s and the first positive electrode current collector projection 212t have a positive electrode porous body 212a and a positive electrode conductive layer 212b provided on the surface of the pores of the positive electrode porous body 212a.

[0054] The negative electrode current collector 213 includes a negative electrode current collector main portion 213s and a first negative electrode current collector projection 213t. The negative electrode current collector main portion 213s is positioned between the second main surface 211b of the insulating film 211 and the negative electrode active material layer 230. The first negative electrode current collector projection 213t is formed continuously with the negative electrode current collector main portion 213s and protrudes from the sides of the positive electrode active material layer 220 and the negative electrode active material layer 230 on the opposite side from the first positive electrode current collector projection 212t in the direction along the winding central axis C. In other words, of the negative electrode current collector 213, the negative electrode current collector main portion 213s is the portion that overlaps with the negative electrode active material layer 230, and the first negative electrode current collector projection 213t is the portion that does not overlap with the negative electrode active material layer 230.

[0055] The first negative electrode current collector projection 213t is formed of the same material as the negative electrode current collector main portion 213s and is provided continuously and integrally. That is, both the negative electrode current collector main portion 213s and the first negative electrode current collector projection 213t have a negative electrode porous body 213a and a negative electrode conductive layer 213b provided on the surface of the pores of the negative electrode porous body 213a.

[0056] The insulating film 211 includes an insulating film main portion 211s, a first insulating film protrusion 211t, and a second insulating film protrusion 211u. The insulating film main portion 211s is positioned between the positive electrode active material layer 220 and the positive electrode current collector main portion 212s, and the negative electrode active material layer 230 and the negative electrode current collector main portion 213s. The first insulating film protrusion 211t and the second insulating film protrusion 211u are formed continuously with the insulating film main portion 211s and protrude from opposite sides of the positive electrode active material layer 220 and the negative electrode active material layer 230. In other words, the first insulating film protrusion 211t and the second insulating film protrusion 211u are portions that do not overlap with the positive electrode active material layer 220 and the negative electrode active material layer 230.

[0057] The first connection portion 215 has a first positive electrode current collector projection 212t and a first insulating film projection 211t. In the first connection portion 215, the first positive electrode current collector projection 212t is laminated on the first main surface 211a of the first insulating film projection 211t. Furthermore, the negative electrode current collector 213 is not provided on the second main surface 211b of the first insulating film projection 211t. The laminated first insulating film projection 211t (insulating film projection) and the first positive electrode current collector projection 212t (first current collector projection) are bent into a U-shape in cross-section. As a result, the second main surfaces 211b of the first insulating film projection 211t face each other, and the first positive electrode current collector projection 212t is provided covering the first main surface 211a on the outside of the first insulating film projection 211t. The protruding portion 212t of the first positive electrode current collector of the first connection portion 215 is electrically connected to the conductive member 14 (external terminal).

[0058] Furthermore, the first insulating film protrusion 211t and the first positive electrode current collector protrusion 212t are bent inward in the portion between the first side surface 211c and the side surface of the negative electrode active material layer 230 (the portion where the first insulating film protrusion 211t is a single layer). As a result, the first connection portion 215 (the portion where the laminated first insulating film protrusion 211t and the first positive electrode current collector protrusion 212t are bent in a U-shape) is inclined towards the inner circumference of the electrode body 10 with respect to the direction along the winding central axis C (the extending direction of the positive electrode current collector main portion 212s and the insulating film main portion 211s). In addition, multiple first connection portions 215 are arranged radially from the inner circumference to the outer circumference in the wound electrode body 10.

[0059] The second connection portion 216 has a first negative electrode current collector projection 213t and a second insulating film projection 211u. In the second connection portion 216, the first negative electrode current collector projection 213t is laminated on the second main surface 211b of the second insulating film projection 211u. Furthermore, the positive electrode current collector 212 is not provided on the first main surface 211a of the second insulating film projection 211u. The laminated second insulating film projection 211u and the first negative electrode current collector projection 213t are bent into a U-shape in cross-section. As a result, the first main surfaces 211a of the second insulating film projection 211u face each other, and the first negative electrode current collector projection 213t is provided covering the second main surface 211b on the outside of the second insulating film projection 211u. The protruding portion 213t of the first negative electrode current collector of the second connection portion 216 is electrically connected to the conductive member 15 (external terminal).

[0060] Furthermore, the second insulating film projection 211u and the first negative electrode current collector projection 213t are bent outward in the portion between the second side surface 211d and the side surface of the positive electrode active material layer 220 (the portion where the second insulating film projection 211u is a single layer). As a result, the second connection portion 216 (the portion where the laminated second insulating film projection 211u and the first negative electrode current collector projection 213t are bent in a U-shape) is inclined towards the outer circumference of the electrode body 10. That is, the second connection portion 216 is inclined on the opposite side from the first connection portion 215. Also, in the wound electrode body 10, multiple second connection portions 216 are arranged radially from the inner circumference to the outer circumference.

[0061] The conductive members 14 and 15 are sheet-like or plate-like members that extend in a direction perpendicular to the winding central axis C of the wound electrode body 10, and are provided in the region overlapping with the first connection portion 215 and the second connection portion 216. The conductive members 14 and 15 are made of a conductor such as aluminum, copper, or stainless steel.

[0062] The conductive member 14 and the first positive electrode current collector projection 212t of the first connection portion 215 are electrically connected by welding, such as laser welding. Similarly, the conductive member 15 and the first negative electrode current collector projection 213t of the second connection portion 216 are electrically connected by welding, such as laser welding. The welding is performed, for example, in an annular region along the winding direction of the first connection portion 215 and the second connection portion 216. This ensures a good connection between the conductive member 14 and the first positive electrode current collector projection 212t of the first connection portion 215, and between the conductive member 15 and the first negative electrode current collector projection 213t of the second connection portion 216. However, the welding is not limited to this, and it is sufficient if the welding is performed at at least one location on each of the first connection portion 215 and the second connection portion 216.

[0063] As described above, the secondary battery 1 of this embodiment has a first connection portion 215 in which the first insulating film protrusion 211t and the first positive electrode current collector protrusion 212t are bent into a U shape, and a second connection portion 216 in which the second insulating film protrusion 211u and the first negative electrode current collector protrusion 213t are bent into a U shape. This makes it possible to increase the contact area between the positive electrode current collector 212 and the negative electrode current collector 213 and the conductive members 14 and 15. Therefore, even if the positive electrode current collector 212 and the negative electrode current collector 213 are formed of a porous material and the effective contact area with the conductive members 14 and 15 is small, it is possible to suppress the increase in electrical resistance in the connection between the positive electrode current collector 212 and the negative electrode current collector 213 and the conductive members 14 and 15. Therefore, the secondary battery 1 of this embodiment can make good connections between the positive electrode current collector 212 and the negative electrode current collector 213 and the external terminals.

[0064] Furthermore, at the first connection portion 215, the protruding portion 212t of the first positive electrode current collector is laminated with the protruding portion 211t of the first insulating film and bent into a U-shape. Similarly, at the second connection portion 216, the protruding portion 213t of the first negative electrode current collector is laminated with the protruding portion 211u of the second insulating film and bent into a U-shape. As a result, even if the positive electrode current collector 212 and the negative electrode current collector 213 each have pores and are formed with a thin film thickness, damage to the protruding portion 212t of the first positive electrode current collector and the protruding portion 213t of the first negative electrode current collector can be suppressed and current collection can be performed.

[0065] Furthermore, the first connection portion 215 and the second connection portion 216 are provided at an inclination toward the inner and outer circumference, respectively, with respect to the direction along the winding central axis C. This allows for a larger contact area between the positive electrode current collector 212 and the negative electrode current collector 213 and the conductive members 14 and 15 compared to the case where the first connection portion 215 and the second connection portion 216 extend in the direction along the winding central axis C.

[0066] Furthermore, the first connection portion 215 is bent and inclined toward the inner circumference side, that is, toward the adjacent positive electrode active material layer 220 side. This prevents the first positive electrode current collector projection 212t of the first connection portion 215 from short-circuiting with the adjacent negative electrode current collector 213 and negative electrode active material layer 230 on the outer circumference side, even if the first connection portion 215 is bent in a U-shape. The second connection portion 216 is bent and inclined toward the outer circumference side, that is, toward the adjacent negative electrode active material layer 230 side. This prevents the first negative electrode current collector projection 213t of the second connection portion 216 from short-circuiting with the adjacent positive electrode current collector 212 and positive electrode active material layer 220 on the inner circumference side, even if the second connection portion 216 is bent in a U-shape.

[0067] Furthermore, in the first connection portion 215, the first side surface 211c of the U-shaped first insulating film projection 211t is located closer to the side surface of the negative electrode active material layer 230 than the side surface 212c of the first positive electrode current collector projection 212t, in the direction along the winding central axis C of the wound electrode body 10. In the second connection portion 216, the second side surface 211d of the U-shaped second insulating film projection 211u is located closer to the side surface of the positive electrode active material layer 220 than the side surface 213c of the first negative electrode current collector projection 213t, in the direction along the winding central axis C of the wound electrode body 10.

[0068] As a result, even if the first insulating film projection 211t and the first positive electrode current collector projection 212t are bent into a U-shape at the first connection portion 215, a short circuit between the first positive electrode current collector projection 212t of the first connection portion 215 and the negative electrode current collector 213 and the negative electrode active material layer 230 can be suppressed. Furthermore, even if the second insulating film projection 211u and the first negative electrode current collector projection 213t are bent into a U-shape at the second connection portion 216, a short circuit between the first negative electrode current collector projection 213t of the second connection portion 216 and the positive electrode current collector 212 and the positive electrode active material layer 220 can be suppressed.

[0069] The separator 240 has a separator main portion 240s, a first separator protrusion 240t (separator protrusion), and a second separator protrusion 240u. The separator main portion 240s is a region that overlaps with the positive electrode active material layer 220 and the negative electrode active material layer 230. The separator main portion 240s is positioned between the positive electrode active material layer 220 and the negative electrode active material layer 230.

[0070] The first separator protrusion 240t and the second separator protrusion 240u are regions that protrude from the sides of the positive electrode active material layer 220 and the negative electrode active material layer 230. The first separator protrusion 240t protrudes on the opposite side from the second separator protrusion 240u. The first separator protrusion 240t is positioned between adjacent first connection portions 215 in the radial direction of the wound electrode body 10. The second separator protrusion 240u is positioned between adjacent second connection portions 216 in the radial direction of the wound electrode body 10.

[0071] This prevents the first positive electrode current collector projection 212t of the first connection portion 215 from short-circuiting with the negative electrode current collector 213 and the negative electrode active material layer 230 located on the inner circumference side when the first connection portion 215 is bent inward. Furthermore, it prevents the first negative electrode current collector projection 213t of the second connection portion 216 from short-circuiting with the positive electrode current collector 212 and the positive electrode active material layer 220 located on the outer circumference side when the second connection portion 216 is bent outward.

[0072] Furthermore, in this embodiment, the insulating film 211, positive electrode current collector 212, and negative electrode current collector 213 of the current collector assembly 210 are porous materials. This allows carrier ions such as lithium ions to pass through the stacking direction of the current collector assembly 210. In other words, during charging and discharging of the secondary battery 1, carrier ions can move between the positive electrode active material layer 220 and the negative electrode active material layer 230 not only through the separator 240 but also through the current collector assembly 210.

[0073] Therefore, the secondary battery 1 of this embodiment can shorten the diffusion distance of carrier ions in the charge-discharge reaction, and the current that can flow under diffusion resistance-limited rate is increased. As a result, even when charging and discharging is performed at a high rate with a large current, the uneven distribution of lithium ion concentration between the positive and negative electrodes can be suppressed, thereby suppressing the generation of irreversible capacity due to the generation of metallic lithium, etc. Therefore, the secondary battery 1 having the current collector assembly 210 according to the first embodiment can improve the charge-discharge characteristics at high rates.

[0074] The configurations of the secondary battery 1 and electrode body 10 described above are merely examples and can be modified as appropriate. For example, the configurations of the first connection portion 215 and the second connection portion 216 shown in Figure 4 are merely examples and can be modified as appropriate. In the first connection portion 215, the second main surfaces 211b of the first insulating film projection 211t are bent into a U-shape so that they are in contact with each other, but the configuration is not limited to this, and a gap may be provided between the second main surfaces 211b. Similarly, in the second connection portion 216, the first main surfaces 211a of the second insulating film projection 211u are bent into a U-shape so that they are in contact with each other, but the configuration is not limited to this, and a gap may be provided between the first main surfaces 211a.

[0075] Furthermore, the lengths of the first connection portion 215 and the second connection portion 216 are not limited to the example shown in Figure 4, and may be formed to be longer. That is, in the wound electrode body 10, the first connection portion 215 and the second connection portion 216 may extend so as to be in contact with and overlapping the first separator protrusion 240t and the second separator protrusion 240u, respectively. Also, in Figure 4, the thicknesses of the negative electrode active material layer 230, negative electrode current collector 213, insulating film 211, positive electrode current collector 212, and positive electrode active material layer 220 are emphasized to make the drawing easier to see.

[0076] Furthermore, the positive electrode current collector 212 and the negative electrode current collector 213 of the current collector assembly 210 are not limited to the example shown in Figure 3, and may be metal foils formed using at least one of the metal materials. In this case, the positive electrode current collector 212 and the negative electrode current collector 213 have a number of through holes penetrating the metal foil in the Z direction, thereby forming a number of micropores. Alternatively, the positive electrode current collector 212 and the negative electrode current collector 213 may be mesh-like metal foils. The shape, diameter, spacing, arrangement, etc., of the multiple through holes in the positive electrode current collector 212 and the negative electrode current collector 213 can be changed as appropriate.

[0077] Figure 5 is an explanatory diagram illustrating an example of a method for bending a current collector assembly. As shown in Figure 5, the electrode body 10 is formed by stacking the separator 240, positive electrode active material layer 220, current collector assembly 210 (positive electrode current collector 212, insulating film 211, and negative electrode current collector 213), negative electrode active material layer 230, and separator 240 in that order (step ST1).

[0078] In step ST1, the current collector assembly 210 (positive electrode current collector 212, insulating film 211, and negative electrode current collector 213) extends in a flat plate shape along the winding central axis C. The length of the insulating film 211 in the direction along the winding central axis C is longer than that of the positive electrode current collector 212 and the negative electrode current collector 213. That is, the first side surface 211c and the second side surface 211d of the insulating film 211 are located further away from the side surface 212c of the positive electrode current collector 212 and the side surface 213c of the negative electrode current collector 213, respectively.

[0079] Next, the laminated first insulating film protrusion 211t and the first positive electrode current collector protrusion 212t are bent into a U-shape (step ST2). Also in step ST2, the laminated second insulating film protrusion 211u and the first negative electrode current collector protrusion 213t are bent into a U-shape. This forms the first connection portion 215 and the second connection portion 216, respectively.

[0080] Specifically, in the first connection portion 215, the second main surfaces 211b of the first insulating film projection 211t face each other, and the first positive electrode current collector projection 212t covers the outer first main surface 211a of the first insulating film projection 211t. Also, in the second connection portion 216, the first main surfaces 211a of the second insulating film projection 211u face each other, and the first negative electrode current collector projection 213t covers the outer second main surface 211b of the second insulating film projection 211u.

[0081] Next, the first connection portion 215 (the portion in which the laminated first insulating film protrusion 211t and the first positive electrode current collector protrusion 212t are bent into a U-shape) and the second connection portion 216 (the portion in which the laminated second insulating film protrusion 211u and the first negative electrode current collector protrusion 213t are bent into a U-shape) are bent and inclined toward the inner and outer circumferences, respectively (step ST3).

[0082] Furthermore, in step ST3, the first separator protrusion 240t and the second separator protrusion 240u are also bent in the same process as the first connection portion 215 and the second connection portion 216.

[0083] By following the above process, an electrode body 10 having a first connecting portion 215 and a second connecting portion 216 can be manufactured. However, the process shown in Figure 5 is merely an example and can be modified as appropriate.

[0084] (Second Embodiment) Figure 6 is a schematic cross-sectional view showing the connection configuration between the current collector and the external terminals of a secondary battery according to the second embodiment. As shown in Figure 6, the secondary battery 1A according to the second embodiment differs from the first embodiment in that a current collector assembly 210A is provided instead of the separator 240.

[0085] In the second embodiment, the electrode body 10A has a plurality of current collector assemblies 210, 210A. In the wound electrode body 10A, the current collector assembly 210A (negative electrode current collector 213, insulating film 211, positive electrode current collector 212), positive electrode active material layer 220, current collector assembly 210 (positive electrode current collector 212, insulating film 211, negative electrode current collector 213), and negative electrode active material layer 230 are stacked in that order from the inner circumference to the outer circumference. Furthermore, the stacking order of current collector assembly 210 and current collector assembly 210A is reversed.

[0086] More specifically, the positive electrode active material layer 220 is positioned between the positive electrode current collector 212 of the current collector assembly 210A and the positive electrode current collector 212 of the current collector assembly 210. The negative electrode active material layer 230 is positioned between the negative electrode current collector 213 of the current collector assembly 210A and the negative electrode current collector 213 of the current collector assembly 210.

[0087] In any of the multiple current collector assemblies 210, 210A, the laminated first insulating film projection 211t and the first positive electrode current collector projection 212t are bent into a U-shape, so that the first positive electrode current collector projection 212t covers the first main surface 211a on the outside of the first insulating film projection 211t. Also, in any of the multiple current collector assemblies 210, 210A, the laminated second insulating film projection 211u and the first negative electrode current collector projection 213t are bent into a U-shape, so that the first negative electrode current collector projection 213t covers the second main surface 211b on the outside of the second insulating film projection 211u.

[0088] As described above, the stacking order of the current collector assembly 210A is reversed with respect to the current collector assembly 210. Therefore, in the current collector assembly 210A, the direction in which the first connection portion 215A and the second connection portion 216A are bent into a U-shape is opposite to the direction in which the first connection portion 215 and the second connection portion 216 are bent into a U-shape in the current collector assembly 210.

[0089] Furthermore, the first connection portion 215A of the current collector assembly 210A and the first connection portion 215 of the current collector assembly 210 are both bent and inclined toward the inner circumference of the wound electrode body 10A. The second connection portion 216A of the current collector assembly 210A and the second connection portion 216 of the current collector assembly 210 are both bent and inclined toward the outer circumference of the wound electrode body 10A.

[0090] In this embodiment, the protruding portions 212t of the first positive electrode current collectors of the first connection portions 215 and 215A are electrically connected to the conductive member 14. The protruding portions 213t of the first negative electrode current collectors of the second connection portions 216 and 216A are electrically connected to the conductive member 15. Therefore, in this embodiment, the contact area between the positive electrode current collector 212 and the conductive member 14, and the contact area between the negative electrode current collector 213 and the conductive member 14 can be increased compared to the first embodiment.

[0091] Furthermore, in this embodiment, current collector assemblies 210 and 210A are provided between adjacent positive electrode active material layers 220 and negative electrode active material layers 230 in the thickness direction (radial direction), so that carrier ions such as lithium ions can pass through the stacking direction of each current collector assembly 210 and 210A.

[0092] (First Modified Example) Figure 7 is a schematic cross-sectional view showing the connection configuration between the current collector and the external terminal of the secondary battery according to the first modified example. As shown in Figure 7, the secondary battery 1B (electrode body 10B) according to the first modified example differs from the second embodiment in that, at the first connection portion 215B of the current collector assembly 210B, the laminated first insulating film protrusion 211t and the first positive electrode current collector protrusion 212t are bent into a U shape, and the first insulating film protrusion 211t is provided covering the first positive electrode current collector protrusion 212t.

[0093] Furthermore, in the second connection portion 216B of the current collector assembly 210B, the laminated second insulating film protrusion 211u and the first negative electrode current collector protrusion 213t are bent into a U-shape, so that the second insulating film protrusion 211u covers the first negative electrode current collector protrusion 213t. In other words, in the current collector assembly 210B, the first positive electrode current collector protrusion 212t and the first negative electrode current collector protrusion 213t are each positioned inside the insulating film 211.

[0094] In the first modified example, compared to the second embodiment described above, the contact area between the positive electrode current collector 212 and the negative electrode current collector 213 and the conductive members 14 and 15 is reduced. However, in the current collector assembly 210B, it is possible to suppress short-circuiting of the first positive electrode current collector protrusion 212t of the first connection portion 215B with the adjacent negative electrode current collector 213 and the negative electrode active material layer 230. Similarly, it is possible to suppress short-circuiting of the first negative electrode current collector protrusion 213t of the second connection portion 216B with the adjacent positive electrode current collector 212 and the positive electrode active material layer 220.

[0095] (Second Modification) Figure 8 is a schematic cross-sectional view showing an electrode body (current collector assembly) according to the second modification. As shown in Figure 8, the secondary battery 1C (electrode body 10C) according to the second modification differs from the first and second embodiments in that the first connection portion 215C of the current collector assembly 210C has a first positive electrode current collector protrusion 212t, a first insulating film protrusion 211t, and a second negative electrode current collector protrusion 213u. The second connection portion 216C has a first negative electrode current collector protrusion 213t, a second insulating film protrusion 211u, and a second positive electrode current collector protrusion 212u.

[0096] The second negative electrode current collector projection 213u (second current collector projection) protrudes from the side surface of the positive electrode active material layer 220 and the negative electrode active material layer 230 on the opposite side of the first negative electrode current collector projection 213t. The second negative electrode current collector projection 213u is laminated on the side (second main surface 211b) of the first insulating film projection 211t opposite to the first positive electrode current collector projection 212t. In the first connection portion 215C, the laminated first positive electrode current collector projection 212t, the first insulating film projection 211t, and the second negative electrode current collector projection 213u are bent into a U-shape, and the second negative electrode current collector projection 213u is sandwiched between the second main surface 211b on the inside of the first insulating film projection 211t. Furthermore, the first positive electrode current collector projection 212t is provided so as to cover the first main surface 211a on the outside of the first insulating film projection 211t.

[0097] The second positive electrode current collector projection 212u protrudes from the side surface of the positive electrode active material layer 220 and the negative electrode active material layer 230 on the opposite side of the first positive electrode current collector projection 212t. The second positive electrode current collector projection 212u is laminated on the side (first main surface 211a) of the second insulating film projection 211u that is opposite to the first negative electrode current collector projection 213t. In the second connection portion 216C, the laminated first negative electrode current collector projection 213t, the second insulating film projection 211u, and the second positive electrode current collector projection 212u are bent into a U-shape, and the second positive electrode current collector projection 212u is sandwiched between the first main surface 211a on the inside of the second insulating film projection 211u. Furthermore, the first negative electrode current collector projection 213t is provided so as to cover the second main surface 211b on the outside of the second insulating film projection 211u.

[0098] In the second modified example, the positive electrode current collector 212 and the negative electrode current collector 213 are provided on the entire surface of the first main surface 211a and the second main surface 211b of the insulating film 211, respectively. That is, in the second modified example, the process of patterning the positive electrode current collector 212 and the negative electrode current collector 213 can be omitted compared to the embodiments and modifications described above.

[0099] (Third Modification) Figure 9 is a schematic cross-sectional view showing the connection configuration between the electrode body (current collector assembly), the external terminals, and the housing of a secondary battery according to the third modification. As shown in Figure 9, in the third modification, the first connection portion 215 and the second connection portion 216 (not shown in Figure 9) of the electrode body 10 (current collector assembly 210) are electrically connected to the conductive members 14, 15 and the housing 20 by welding.

[0100] The first positive electrode current collector projection 212t of the first connection portion 215 (see Figure 4) is electrically connected to the conductive member 14 by welding. The conductive member 14 is electrically connected to the cover portion 22 via the connecting member 14a. For example, the conductive member 14 is electrically connected to the connecting member 14a by welding at the location indicated by arrow A1. Also, the connecting member 14a is electrically connected to the cover portion 22 by welding at the location indicated by arrow A2.

[0101] The protruding portion 213t of the first negative electrode current collector of the second connection portion 216 (see Figure 4) is electrically connected to the conductive member 15 by welding. The protruding portion 213t of the first negative electrode current collector is electrically connected to the conductive member 15 by welding at the location indicated by arrow B1, for example. The conductive member 15 is also electrically connected to the bottom of the main body portion 21 by welding at the location indicated by arrow B2.

[0102] With the above configuration, the electrode body 10 (current collector assembly 210) is electrically connected to the conductive members 14, 15 and the housing 20. Note that the configuration shown in Figure 9 is merely an example, and the connection between the electrode body 10 (current collector assembly 210) and the conductive members 14, 15 and the housing 20 can be in any configuration.

[0103] (Fourth Modification) Figure 10 is a schematic cross-sectional view showing the connection configuration between the electrode body (current collector assembly), the external terminals and the housing of the secondary battery according to the fourth modification. As shown in Figure 10, in the fourth modification, unlike the third and fourth modifications, a part of the protruding portion 213t of the first negative electrode current collector of the second connection portion 216 is electrically connected to the side of the main body portion 21 by welding.

[0104] For example, the protruding portion 213t of the first negative electrode current collector of the second connection portion 216 is electrically connected to the conductive member 15 by welding at the locations indicated by arrows C2 and C3. The conductive member 15 is electrically connected to the bottom of the main body portion 21 by welding at the location indicated by arrow C1. Furthermore, the protruding portion 213t of the first negative electrode current collector of the second connection portion 216 is electrically connected to the side of the main body portion 21 at the location indicated by arrow C4, without going through the conductive member 15. The connection between the protruding portion 213t of the first negative electrode current collector of the second connection portion 216 and the side of the main body portion 21 at the location indicated by arrow C4 may be, for example, by welding. In this fourth modification, the electrical resistance in the connection between the negative electrode current collector 213 and the main body portion 21 can be suppressed.

[0105] The configurations shown in Figures 9 to 10 are not limited to the secondary battery 1 according to the first embodiment, but can be combined with the second embodiment, the first modified example, and the second modified example.

[0106] (Fifth Modification) Figure 11 is an explanatory diagram illustrating the configuration of the current collector assembly according to the fifth modification. In Figure 11, for ease of understanding, the current collector assembly 210D is unfolded into a flat plate shape, and the positive electrode current collector 212, insulating film 211, and negative electrode current collector 213 are disassembled and schematically shown.

[0107] As shown in Figure 11, in the fifth modified example, a plurality of first positive electrode current collector protrusions 212t are provided on the outer edge (upper edge in Figure 11) along the winding direction of the positive electrode current collector 212. The plurality of first positive electrode current collector protrusions 212t are spaced apart by notches. In other words, the plurality of first positive electrode current collector protrusions 212t are arranged in a comb-like shape.

[0108] Furthermore, multiple first insulating film protrusions 211t and multiple second insulating film protrusions 211u are provided on the outer edge (upper and lower edges in Figure 11) along the winding direction of the insulating film 211. Multiple first negative electrode current collector protrusions 213t are provided on the outer edge (lower edge in Figure 11) along the winding direction of the negative electrode current collector 213. The multiple first insulating film protrusions 211t, multiple second insulating film protrusions 211u, and multiple first negative electrode current collector protrusions 213t are each arranged in a comb-like pattern.

[0109] Thus, the first positive electrode current collector protrusions 212t are not limited to being provided continuously along the winding direction of the positive electrode current collector 212, and multiple first positive electrode current collector protrusions 212t may be provided spaced apart. The widths of the multiple first positive electrode current collector protrusions 212t and the spacing between adjacent first positive electrode current collector protrusions 212t may differ from each other.

[0110] The first insulating film protrusion 211t, the second insulating film protrusion 211u, and the first negative electrode current collector protrusion 213t may also be provided in multiples. The widths and spacings of the multiple first insulating film protrusions 211t, the multiple second insulating film protrusions 211u, and the multiple first negative electrode current collector protrusions 213t may differ from each other.

[0111] In the fifth modified example, the first positive electrode current collector projection 212t, the first insulating film projection 211t, the second insulating film projection 211u, and the first negative electrode current collector projection 213t are provided spaced apart from each other. Therefore, when forming the first connection portion 215 and the second connection portion 216, they can be easily bent into a U-shape, or easily bent towards the outer or inner circumference. The configuration shown in the fifth modified example can be combined with the first embodiment, the second embodiment, and each of their modified examples described above.

[0112] The embodiments described above relate to wound electrode bodies, but are not limited to "wound" structures. For example, a laminated electrode body may have a structure in which multiple sheet-like positive and negative electrodes are stacked with a layer that functions as a separator in between.

[0113] In that case, for example, the battery comprises a laminated battery continuum in which multiple sheets of a sheet-like positive electrode having a positive electrode mixture layer on both sides of an aluminum foil and multiple sheets of a sheet-like negative electrode having a negative electrode mixture layer on both sides of a copper foil are laminated together with a separator between them, an electrolyte, and a positive electrode pull tab and a negative electrode pull tab drawn out from the battery element, are arranged in a continuous manner in the same direction. The laminated battery continuum, which is bound together as one unit, may be folded in a zigzag pattern or a serrated pattern.

[0114] In that case, the positive electrode lead tab and the negative electrode lead tab have the structure described in claim 1. In this case, the positive electrode lead tab and the negative electrode lead tab may be inclined with respect to one of the main surfaces of the sheet-like positive electrode or negative electrode.

[0115] The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit its interpretation. The present invention may be modified or improved without departing from its spirit, and equivalents thereof are also included.

[0116] 1, 1A, 1B, 1C Secondary battery 10, 10A, 10B, 10C Electrode body 20 Housing 14, 15 Conductive member 210, 210A, 210B, 210C, 210D Current collector assembly 211 Insulating film 211s Main part of insulating film 211t First insulating film protrusion 211u Second insulating film protrusion 212 Positive electrode current collector 212a Positive electrode porous body 212b Positive electrode conductive layer 212s Main part of positive electrode current collector 212t First positive electrode current collector protrusion 212u Second positive electrode current collector protrusion 213 Negative electrode current collector 213a Negative electrode porous body 213b Negative electrode conductive layer 213s Main part of negative electrode current collector 213t First negative electrode current collector protrusion 213u Second negative electrode current collector protrusion 215, 215A, 215B, 215C First connection part 216, 216A, 216B, 216C Second connection part 220 Positive electrode active material layer 230 Negative electrode active material layer 240 Separator

Claims

1. An electrode body comprising: an insulating film having a first main surface and a second main surface opposite to the first main surface, and being a porous material; a positive electrode current collector provided on the first main surface of the insulating film, being a porous material; a positive electrode active material layer provided on the positive electrode current collector; a negative electrode current collector provided on the second main surface of the insulating film, being a porous material; and a negative electrode active material layer provided on the negative electrode current collector, wherein the electrode body is wound up and the positive electrode active material layer, the positive electrode current collector, the insulating film, the negative electrode current collector, and the negative electrode active material layer are laminated together, at least one of the positive electrode current collector and the negative electrode current collector includes a first current collector projection that protrudes from at least one side surface of the positive electrode active material layer and the negative electrode active material layer, and the insulating film includes an insulating film projection that protrudes from at least one side surface of the positive electrode active material layer and the negative electrode active material layer and is laminated with the first current collector projection. A secondary battery in which the laminated insulating film protrusion and the first current collector protrusion are bent into a U-shape, the first current collector protrusion is provided so as to cover the outer main surface of the insulating film protrusion, and the first current collector protrusion and an external terminal are electrically connected.

2. The secondary battery according to claim 1, wherein the portions of the laminated insulating film protrusions and the first current collector protrusions that are bent into a U-shape are provided at an inclination toward the inner or outer circumference of the wound electrode body.

3. A secondary battery according to claim 1 or claim 2, comprising a separator disposed between the wound electrode bodies, wherein the separator has separator protrusions protruding from at least one side surface of the positive electrode active material layer and the negative electrode active material layer.

4. The secondary battery according to any one of claims 1 to 3, wherein the side surface of the U-shaped bent insulating film projection is located closer to the side surface of the positive electrode active material layer or the negative electrode active material layer than the side surface of the first current collector projection, in a direction along the winding central axis of the wound electrode body.

5. The secondary battery according to any one of claims 1 to 4, wherein when the stacked positive electrode current collector, insulating film and negative electrode current collector form a current collector assembly, the electrode body has a plurality of current collector assemblies, and the current collector assembly, the positive electrode active material layer, the other current collector assembly, and the negative electrode active material layer are stacked in that order, and the stacking order of one current collector assembly and the other current collector assembly is reversed.

6. The secondary battery according to claim 5, wherein in any of the plurality of current collector assemblies, the laminated insulating film protrusion and the first current collector protrusion are bent into a U-shape, the first current collector protrusion is provided covering the outer main surface of the insulating film protrusion, and the first current collector protrusion and the external terminal are electrically connected.

7. The secondary battery according to claim 5, wherein in one current collector assembly, the laminated insulating film protrusion and the first current collector protrusion are bent into a U-shape, and the first current collector protrusion is provided covering the outer main surface of the insulating film protrusion, and the first current collector protrusion and the external terminal are electrically connected, and in the other current collector assembly, the laminated insulating film protrusion and the first current collector protrusion are bent into a U-shape, and the insulating film protrusion is provided covering the outer main surface of the first current collector protrusion.

8. The secondary battery according to any one of claims 1 to 7, wherein the other of the positive electrode current collector and the negative electrode current collector includes a second current collector projection that protrudes from at least one side surface of the positive electrode active material layer and the negative electrode active material layer, the second current collector projection is laminated on the surface of the insulating film projection opposite to the first current collector projection, the laminated insulating film projection, the first current collector projection and the second current collector projection are bent into a U-shape, the first current collector projection is provided covering the outer main surface of the insulating film projection, and the second current collector projection is sandwiched between the inner main surfaces of the insulating film projection.

9. The secondary battery according to any one of claims 1 to 8, wherein the positive electrode current collector includes a positive electrode current collector main portion disposed between the first main surface of the insulating film and the positive electrode active material layer, and a first positive electrode current collector protrusion formed continuously with the positive electrode current collector main portion and protruding from the side surface of the positive electrode active material layer, and the negative electrode current collector includes a negative electrode current collector main portion disposed between the second main surface of the insulating film and the negative electrode active material layer, and a first negative electrode current collector protrusion formed continuously with the negative electrode current collector main portion and protruding from the side surface of the negative electrode active material layer.

10. The secondary battery according to claim 9, wherein the insulating film includes a first insulating film projection laminated with the first positive electrode current collector projection, and a second insulating film projection located on the opposite side of the first insulating film projection and laminated with the first negative electrode current collector projection, the laminated first insulating film projection and the first positive electrode current collector projection are bent into a U-shape so that the first positive electrode current collector projection covers the outer main surface of the first insulating film projection, and the laminated second insulating film projection and the first negative electrode current collector projection are bent into a U-shape so that the first negative electrode current collector projection covers the outer main surface of the second insulating film projection.

Images