Secondary battery

Abstract

A secondary battery according to the present invention comprises: an insulating film that is a porous body and that 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 that is 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 that is a porous body and that is provided on the second main surface of the insulating film; and a negative electrode active material layer provided on the negative electrode current collector. An electrode body formed by laminating the positive electrode active material layer, the positive electrode current collector, the insulating film, then negative electrode current collector, and the negative electrode active material layer is wound. The wound electrode body has a plurality of first connecting portions electrically connected to an external positive electrode terminal, and a plurality of second connecting portions electrically connected to an external negative electrode terminal. The plurality of first connecting portions and the plurality of second connecting portions are provided on the same side on an outer edge of the wound electrode body, in a direction along a rotation center axis, and are arranged being spaced apart from each other along the winding direction of the electrode body.

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] In wound-type secondary batteries, where the electrode body is wound around the battery, there is a need to improve the volumetric energy density.

[0005] The present invention aims to provide a secondary battery that can improve volumetric energy density.

[0006] 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 and is 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 and is provided on the second main surface of the insulating film; and a negative electrode active material layer provided on the negative electrode current collector. The electrode body, which is constructed 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 up, and the wound electrode body has a plurality of first connection parts which are electrically connected to an external positive electrode terminal, and a plurality of second connection parts which are electrically connected to an external negative electrode terminal, and the plurality of first connection parts and the plurality of second connection parts are provided on the outer edge on the same side in the direction along the rotational axis of the wound electrode body, and are arranged apart from each other in the winding direction of the electrode body.

[0007] According to the secondary battery of the present invention, the volumetric energy density can be improved.

[0008] 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 plan view showing the arrangement of a plurality of first connection parts and a plurality of second connection parts in the secondary battery according to the first embodiment. Figure 5 is a plan view when the current collector assembly is unfolded. Figure 6 is a perspective view when the current collector assembly is unfolded. Figure 7 is a schematic cross-sectional view showing the connection configuration between the plurality of first connection parts and a plurality of second connection parts and the external terminals in the secondary battery according to the first embodiment. Figure 8 is a plan view when the current collector assembly according to the first modified example is unfolded. Figure 9 is a perspective view when the current collector assembly according to the first modified example is unfolded. Figure 10 is a plan view when the current collector assembly according to the second modified example is unfolded. Figure 11 is a plan view when the current collector assembly according to the third modified example is unfolded. Figure 12 is a perspective view when the current collector assembly according to the third modified example is unfolded. Figure 13 is a plan view of the current collector assembly according to the fourth modified example when unfolded. Figure 14 is a schematic cross-sectional view showing the connection configuration between a plurality of first connection parts and a plurality of second connection parts and an external terminal of the secondary battery according to the fourth modified example. Figure 15 is a schematic plan view showing the arrangement of a plurality of first connection parts and a plurality of second connection parts in the secondary battery according to the second embodiment. Figure 16 is an exploded perspective view showing an example of the connection configuration between a plurality of first connection parts and a plurality of second connection parts and an external terminal in the secondary battery according to the second embodiment. Figure 17 is a schematic plan view showing the arrangement of a plurality of first connection parts and a plurality of second connection parts in the secondary battery according to the third embodiment. Figure 18 is a cross-sectional view showing an example of the connection configuration between a plurality of first connection parts and a plurality of second connection parts and an external terminal in the secondary battery according to the third embodiment. Figure 19 is a plan view of the electrode body according to the third embodiment as seen from the negative electrode active material layer side when unfolded. Figure 20 is a plan view of the electrode body according to the third embodiment as seen from the positive electrode active material layer side when unfolded. Figure 21 is a schematic cross-sectional view showing the connection configuration between the multiple first connection parts and the multiple second connection parts and the external terminal in the electrode body according to the fifth modified example.

[0009] 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.

[0010] (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.

[0011] 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 positive electrode active material layer 220 is arranged on the inner circumference side and the negative electrode active material layer 230 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.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] In the secondary battery 1 according to the first embodiment, the conductive member 14 and the conductive member 15 are arranged on the same side of the wound electrode assembly 10 in a direction along the central winding axis. That is, no connection structure with an external terminal is provided on the side of the wound electrode assembly 10 opposite to the conductive member 14 and the conductive member 15 (the lower side in FIG. 1).

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

[0017] As shown in FIG. 2, in the secondary battery 1, the electrode assembly 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 laminated in this order from the inner circumferential side to the outer circumferential side. The positive electrode active material layer 220 and the negative electrode active material layer 230 included in the electrode assembly 10 are layered members for the charge-discharge reaction of the secondary battery 1 according to the first embodiment. In the following description, one side in the thickness direction of the electrode assembly 10 may be referred to as the Z1 direction (outer circumferential side), and the other side in the thickness direction of the electrode assembly 10 may be referred to as the Z2 direction (inner circumferential side). It should be noted that the lamination order of the electrode assembly 10 and the current collector assembly 210 shown in FIG. 2 and FIG. 3 is merely an example, and the lamination order may be vertically inverted.

[0018] It should be noted that although FIG. 2 shows a configuration in which the electrode assembly 10 is wound two turns, the number of windings of the electrode assembly 10 is not limited to two turns, and the electrode assembly 10 may be wound three or more turns. A separator 240 is arranged on the outer circumferential side or the inner circumferential side of the electrode assembly 10 and is wound together with the electrode assembly 10. Furthermore, an insulating layer different from the separator 240 may be provided on the outer circumferential side of the wound electrode assembly 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 －６refers to a material of S / m or less. This can suppress a short circuit 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, increase the strength thereof, and achieve both 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 having an average pore diameter 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 contains, for example, a polymer material. The insulating film 211 preferably contains at least one selected from the group consisting of polyolefin, polyimide, polyamide, polyester, cellulose, glass, and metal oxide, and is particularly preferably polyparaphenylene terephthalamide. Here, an example of the insulating film 211 containing glass is glass filter paper such as GC-50 manufactured by ADVANTEC. Further, an example of the insulating film 211 containing a metal oxide is a porous alumina membrane. This can 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 positive electrode active materials capable of intercalating and deintercalating lithium. However, the positive electrode active material layer 220 may further contain one or more 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 may be a coating method, for example.

[0035] The type of positive electrode active material is not particularly limited, and specifically, it is a lithium-containing compound or the like. A 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 include elements belonging to any one of Groups 2 to 15 in the long-form periodic table.

[0036] The type of lithium-containing compound is not particularly limited, and specific examples of lithium-containing compounds include oxides, phosphate compounds, silicate compounds, and borate compounds. A specific example of an oxide is 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 phosphate compounds include LiFePO ４ , LiMnPO ４ , LiFe ０．５ Mn ０．５ PO ４ and LiFe ０．３ Mn ０．７ PO ４ and the like.

[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 to 7, 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 plan view showing the arrangement of a plurality of first connection parts and a plurality of second connection parts in a secondary battery according to the first embodiment. Figure 5 is a plan view when the current collector assembly is unfolded. Figure 6 is a perspective view when the current collector assembly is unfolded. Figure 7 is a schematic cross-sectional view showing the connection configuration between the plurality of first connection parts and a plurality of second connection parts and the external terminals in a secondary battery according to the first embodiment.

[0050] Figure 4 is a plan view of the wound electrode body 10 as seen from the direction along the rotational axis (the side of the lid portion 22 in Figure 1). Figures 5 and 6 show the current collector assembly 210 unfolded in a planar manner, with the positive electrode active material layer 220 and the negative electrode active material layer 230 omitted, for the sake of clarity.

[0051] Furthermore, in the following description, the direction along the rotational axis of the wound electrode body 10 is defined as the C direction, the winding direction as the R direction, and the thickness direction (radial direction) as the Z direction. The Z direction includes the Z1 and Z2 directions described above.

[0052] As shown in Figure 4, the wound electrode body 10 has a plurality of first connection portions 210s that are electrically connected to the conductive member 14 (external positive electrode terminal) and a plurality of second connection portions 210t that are electrically connected to the conductive member 15 (external negative electrode terminal). The plurality of first connection portions 210s and the plurality of second connection portions 210t are provided on the outer edge of the wound electrode body 10 on the same side in the C direction along the rotational axis. The plurality of first connection portions 210s and the plurality of second connection portions 210t are arranged separately from each other along the R direction (winding direction of the electrode body 10). In the following description, if it is not necessary to distinguish between the plurality of first connection portions 210s and the plurality of second connection portions 210t, they may simply be referred to as a plurality of connection portions.

[0053] In the wound electrode body 10, a region where multiple first connection portions 210s are provided and a region where multiple second connection portions 210t are provided are arranged separately on either side of the rotational axis of the electrode body 10. In the example shown in Figure 4, multiple first connection portions 210s are provided in the region to the right of the imaginary line CL perpendicular to the rotational axis, and multiple second connection portions 210t are provided in the region to the left of the imaginary line CL.

[0054] The conductive members 14 and 15 are sheet-like or plate-like members formed from a conductor such as aluminum, copper, or stainless steel. Conductive member 14 (shown by a dashed line in Figure 4) is semicircular and is positioned to overlap the region where the multiple first connection portions 210s are provided. Conductive member 15 (shown by a dashed line in Figure 4) is semicircular and symmetrical to conductive member 14, and is positioned to overlap the region where the multiple second connection portions 210t are provided.

[0055] As shown in Figures 5 and 6, a plurality of notches 210n are provided on the outer edge of the current collector assembly 210 (electrode body 10) in the C direction. The plurality of first connection portions 210s and the plurality of second connection portions 210t are the portions between adjacent plurality of notches 210n. In other words, the plurality of first connection portions 210s and the plurality of second connection portions 210t are spaced apart along the R direction (winding direction of the electrode body 10) by the plurality of notches 210n.

[0056] Multiple first connection portions 210s are bent in the Z direction (towards the outer circumference of the electrode body 10) so that the positive electrode current collector 212 faces upward. Multiple second connection portions 210t are bent in the opposite direction from the multiple first connection portions 210s (towards the inner circumference of the electrode body 10) so that the negative electrode current collector 213 faces upward. As a result, multiple first connection portions 210s are electrically connected to the conductive member 14, and multiple second connection portions 210t are electrically connected to the conductive member 15.

[0057] More specifically, as shown in Figure 7, 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.

[0058] The positive electrode current collector 212 includes a positive electrode current collector main portion 212s and a positive electrode current collector projection portion 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 positive electrode current collector projection portion 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 positive electrode current collector projection portion 212t is the portion that does not overlap with the positive electrode active material layer 220.

[0059] The 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 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.

[0060] The negative electrode current collector 213 includes a negative electrode current collector main portion 213s and a 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 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 same side as the positive electrode current collector projection 212t in the C direction along the rotational axis. 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 negative electrode current collector projection 213t is the portion that does not overlap with the negative electrode active material layer 230.

[0061] The 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 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.

[0062] The insulating film 211 includes an insulating film main portion 211s and an insulating film protrusion 211t. 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 insulating film protrusion 211t is formed continuously with the insulating film main portion 211s and protrudes from the sides of the positive electrode active material layer 220 and the negative electrode active material layer 230. In other words, the insulating film protrusion 211t is a portion that does not overlap with the positive electrode active material layer 220 and the negative electrode active material layer 230.

[0063] The multiple first connection portions 210s and the multiple second connection portions 210t are each formed from portions of the positive electrode current collector 212, insulating film 211, and negative electrode current collector 213 that protrude from the sides of the positive electrode active material layer 220 and the negative electrode active material layer 230 (positive electrode current collector protrusion 212t, insulating film protrusion 211t, and negative electrode current collector protrusion 213t). Furthermore, the multiple first connection portions 210s and the multiple second connection portions 210t are each constructed by laminating the positive electrode current collector protrusion 212t, insulating film protrusion 211t, and negative electrode current collector protrusion 213t. More specifically, the positive electrode current collector protrusion 212t is laminated on the first main surface 211a of the insulating film protrusion 211t. The negative electrode current collector protrusion 213t is laminated on the second main surface 211b of the insulating film protrusion 211t.

[0064] Multiple first connection portions 210s and multiple second connection portions 210t are bent in different directions in the Z direction (thickness direction of the electrode body 10). Multiple first connection portions 210s are bent towards the outer circumference of the wound electrode body 10. As a result, the positive electrode current collector 212 (positive electrode current collector protrusion 212t) is electrically connected to the conductive member 14. Multiple second connection portions 210t are bent towards the inner circumference of the wound electrode body 10. As a result, the negative electrode current collector 213 (negative electrode current collector protrusion 213t) is electrically connected to the conductive member 15.

[0065] Furthermore, the separator 240 includes a separator main portion 240s and a separator projection portion 240t. The separator main portion 240s is positioned between the positive electrode active material layer 220 and the negative electrode active material layer 230 in the wound electrode body 10. The separator projection portion 240t protrudes from the sides of the positive electrode active material layer 220 and the negative electrode active material layer 230 on the same side as the plurality of first connection portions 210s and the plurality of second connection portions 210t. In the wound electrode body 10, the separator projection portion 240t of the separator 240 is positioned between adjacent first connection portions 210s and between adjacent second connection portions 210t, with a gap in the Z direction.

[0066] This prevents a short circuit between the negative electrode current collector 213 (negative electrode current collector protrusion 213t) of one first connection portion 210s and the positive electrode current collector 212 (positive electrode current collector protrusion 212t) of the other first connection portion 210s when the adjacent first connection portion 210s is bent. Similarly, this prevents a short circuit between the negative electrode current collector 213 (negative electrode current collector protrusion 213t) of one second connection portion 210t and the positive electrode current collector 212 (positive electrode current collector protrusion 212t) of the other second connection portion 210t when the adjacent second connection portion 210t is bent.

[0067] As described above, in this embodiment, the secondary battery 1 has a plurality of first connection parts 210s that are electrically connected to the conductive member 14 (external positive electrode terminal) and a plurality of second connection parts 210t that are electrically connected to the conductive member 15 (external negative electrode terminal), all of which are provided on the same side in the C direction along the rotational axis of the wound electrode body 10. That is, the lower end side of the wound electrode body 10 (the bottom side of the main body 21 shown in Figure 1) is not provided with a connection configuration to an external terminal.

[0068] This makes it possible to reduce the overall volume of the electrode body 10, including the connection parts, compared to a configuration in which connection parts are provided at both ends of the wound electrode body 10. Therefore, the secondary battery 1 of this embodiment can improve the volumetric energy density.

[0069] Furthermore, in each of the multiple first connection portions 210s and multiple second connection portions 210t, an insulating film protrusion 211t is laminated between the positive electrode current collector protrusion 212t and the negative electrode current collector protrusion 213t. 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, the insulating film protrusion 211t is laminated with them, thereby suppressing damage to the positive electrode current collector protrusion 212t and the negative electrode current collector protrusion 213t and enabling current collection.

[0070] 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.

[0071] 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.

[0072] 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 arrangement of the multiple first connection parts 210s and multiple second connection parts 210t shown in Figure 4 is merely an example and can be modified as appropriate. The shapes and dimensions (width in the R direction and length in the Z direction when bent) of the multiple first connection parts 210s and multiple second connection parts 210t shown in Figures 5 and 6 are schematic representations and can be modified as appropriate.

[0073] In Figure 7, for the sake of clarity, the multiple first connection parts 210s and multiple second connection parts 210t are shown folded into flat plates, but the figure is not limited to this, and they may be folded in a curved shape to have a curved surface. Also, in Figure 7, for the sake of clarity, 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.

[0074] Furthermore, the lengths of the multiple first connecting portions 210s and the multiple second connecting portions 210t may be longer than those shown in the example in Figure 7. That is, in the wound electrode body 10, the multiple first connecting portions 210s and the multiple second connecting portions 210t may each extend so as to be in contact with and overlapping the separator protrusion 240t.

[0075] 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.

[0076] (First Modified Example) Figure 8 is a plan view of the current collector assembly according to the first modified example when unfolded. Figure 9 is a perspective view of the current collector assembly according to the first modified example when unfolded. As shown in Figures 8 and 9, in the first modified example, unlike the first embodiment, a plurality of slits 210p are provided on the outer edge in the C direction along the rotational axis of the current collector assembly 210A (electrode body 10A).

[0077] Each of the multiple slits 210p extends in the C direction from the outer edge of the current collector assembly 210A and is arranged in the R direction. The multiple first connection portions 210s and the multiple second connection portions 210t are separated and arranged along the R direction (winding direction of the electrode body 10) by the multiple slits 210p. In the first modification, the distance between adjacent multiple first connection portions 210s and the distance between adjacent multiple second connection portions 210t can be shortened. As a result, in the first modification, the number, area, and arrangement density of the multiple first connection portions 210s and the multiple second connection portions 210t can be increased.

[0078] (Second Modification) Figure 10 is a plan view of the current collector assembly according to the second modification when unfolded. As shown in Figure 10, in the second modification, unlike the first modification, an opening 210q with a width larger than the multiple slits 210p is formed at the base end of the multiple slits 210p of the current collector assembly 210B (electrode body 10B). The base end of the multiple slits 210p is the end of the multiple slits 210p in the direction away from the outer edge in the direction along the rotational axis of the electrode body 10B, and corresponds to the portion in which the first connecting portion 210s and the second connecting portion 210t are bent in the Z direction.

[0079] When multiple first connection portions 210s and multiple second connection portions 210t are separated by multiple slits 210p, the distance between adjacent first connection portions 210s and second connection portions 210t is short, so there is a possibility that the negative electrode current collector 213 (negative electrode current collector protrusion 213t) and the positive electrode current collector 212 (positive electrode current collector protrusion 212t) will short-circuit. In this modified example, since an opening 210q is provided at the base end of the slit 210p, even when adjacent first connection portions 210s and second connection portions 210t are bent in opposite directions, it is possible to suppress short-circuiting between the negative electrode current collector 213 (negative electrode current collector protrusion 213t) and the positive electrode current collector 212 (positive electrode current collector protrusion 212t).

[0080] (Third Modification) Figure 11 is a plan view of the current collector assembly according to the third modification when unfolded. Figure 12 is a perspective view of the current collector assembly according to the third modification when unfolded. As shown in Figures 11 and 12, in the third modification, unlike the first and second modifications, insulating layers 215 and 216 are formed to cover the base ends of the multiple slits 210p of the current collector assembly 210C (electrode body 10C) (the insulating layer 215 is not shown in Figure 11).

[0081] The insulating layer 215 is provided on the surface of the positive electrode current collector 212 and extends along the R direction (winding direction of the electrode body 10C), covering the base ends of the multiple slits 210p. The insulating layer 216 is provided on the surface of the negative electrode current collector 213 and extends along the R direction (winding direction of the electrode body 10C), covering the base ends of the multiple slits 210p. The insulating layers 215 and 216 are, for example, insulating tapes and are bonded to the surface of the positive electrode current collector 212 and the surface of the negative electrode current collector 213, respectively.

[0082] In the third modified example, since insulating layers 215 and 216 are provided, short-circuiting of the negative electrode current collector 213 (negative electrode current collector protrusion 213t) and the positive electrode current collector 212 (positive electrode current collector protrusion 212t) at the base end of the slit 210p can be suppressed, similar to the second modified example described above.

[0083] The insulating layers 215 and 216 shown in the third modified example can also be combined with those of the first embodiment. That is, in a configuration in which a notch 210n is provided in the current collector assembly 210 (see Figures 5 and 6), the insulating layers 215 and 216 may be provided covering a portion of the notch 210n.

[0084] (Fourth Modification) Figure 13 is a plan view of the current collector assembly according to the fourth modification when unfolded. Figure 14 is a schematic cross-sectional view showing the connection configuration of the secondary battery according to the fourth modification, which includes a plurality of first connection parts and a plurality of second connection parts, and an external terminal. As shown in Figures 13 and 14, in the fourth modification, unlike the first embodiment and each of the modifications, the plurality of first connection parts 210s of the current collector assembly 210D (electrode body 10D) include a first insulating layer 217, and the plurality of second connection parts 210t include a second insulating layer 218 (not shown in Figure 13).

[0085] In multiple first connection points 210s, the first insulating layer 217 is provided covering the negative electrode current collector 213 (negative electrode current collector protrusion 213t). That is, in multiple first connection points 210s, the first insulating layer 217 is provided on the side of the insulating film 211 opposite to the positive electrode current collector 212 (positive electrode current collector protrusion 212t). Also, in multiple second connection points 210t, the second insulating layer 218 is provided covering the positive electrode current collector 212 (positive electrode current collector protrusion 212t). That is, in multiple second connection points 210t, the first insulating layer 217 is provided on the side of the insulating film 211 opposite to the negative electrode current collector 213 (negative electrode current collector protrusion 213t).

[0086] Since the first insulating layer 217 is provided, even if the multiple first connection portions 210s are formed to be longer than the separator protrusions 240t, or if the separator protrusions 240t are not provided, short circuits between adjacent multiple first connection portions 210s can be suppressed. In other words, short circuits between the negative electrode current collector 213 (negative electrode current collector protrusion 213t) of one first connection portion 210s and the positive electrode current collector 212 (positive electrode current collector protrusion 212t) of the other first connection portion 210s can be suppressed.

[0087] Similarly, since a second insulating layer 218 is provided, even if multiple second connection portions 210t are formed to be longer than the separator protrusions 240t, or if the separator protrusions 240t are not provided, short circuits between adjacent multiple second connection portions 210t can be suppressed. In other words, short circuits between the negative electrode current collector 213 (negative electrode current collector protrusion 213t) of one second connection portion 210t and the positive electrode current collector 212 (positive electrode current collector protrusion 212t) of the other first connection portion 210s can be suppressed.

[0088] Furthermore, the first insulating layer 217 and the second insulating layer 218 shown in the fourth modified example can also be combined with those of the first to third modified examples. That is, for example, in a configuration in which a slit 210p is provided in the current collector assembly 210A (see Figures 8 and 9), the first insulating layer 217 may be provided in each of the multiple first connection portions 210s, and the second insulating layer 218 may be provided in each of the multiple second connection portions 210t.

[0089] (Second Embodiment) Figure 15 is a schematic plan view showing the arrangement of a plurality of first connection parts and a plurality of second connection parts in a secondary battery according to the second embodiment. Figure 16 is an exploded perspective view showing an example of the connection configuration between the plurality of first connection parts and a plurality of second connection parts and an external terminal in a secondary battery according to the second embodiment. As shown in Figures 15 and 16, in the secondary battery 1A according to the second embodiment, unlike the first embodiment and its various modifications, the plurality of first connection parts 210s and a plurality of second connection parts 210t of the current collector assembly 210E (electrode body 10E) are arranged along the radial direction of the electrode body 10E.

[0090] In the second embodiment, the shapes and stacking configurations of the multiple first connecting portions 210s and the multiple second connecting portions 210t are the same as those in the first embodiment described above, and a repeated explanation will be omitted.

[0091] As shown in Figure 15, the multiple first connection portions 210s and the multiple second connection portions 210t are arranged along the radial direction (thickness direction) of the electrode body 10E. The multiple first connection portions 210s and the multiple second connection portions 210t arranged along the radial direction (thickness direction) are alternately arranged along the winding direction of the electrode body 10E. The multiple first connection portions 210s arranged along the radial direction (thickness direction) have an angle of about 45° with respect to the multiple second connection portions 210t arranged along the radial direction (thickness direction).

[0092] The number and arrangement of the multiple first connecting portions 210s and multiple second connecting portions 210t are shown schematically for the sake of clarity and can be changed as appropriate. For example, multiple first connecting portions 210s arranged along the radial direction (thickness direction) may be formed to overlap each other. Multiple second connecting portions 210t arranged along the radial direction (thickness direction) may be formed to overlap each other.

[0093] As shown in Figure 16, the secondary battery 1A includes conductive members 14A and 15A and an insulating plate 16. The insulating plate 16 is positioned between the conductive members 14A and 15A. The conductive member 14A has a plurality of first portions 14Aa, a second portion 14Ab, and a third portion 14Ac. Each of the plurality of first portions 14Aa extends radially and is electrically connected to a plurality of first connection portions 210s of the electrode body 10E. The second portion 14Ab connects the inner circumferences of the plurality of first portions 14Aa. The third portion 14Ac is an annular member that connects the outer circumferences of the plurality of first portions 14Aa. An opening 14Ad is provided in the region enclosed by the plurality of first portions 14Aa, the second portion 14Ab, and the third portion 14Ac.

[0094] The conductive member 15A has a plurality of first portions 15Aa, a second portion 15Ab, and a third portion 15Ac. Each of the plurality of first portions 15Aa extends radially and is electrically connected to a plurality of second connection portions 210t of the electrode body 10E. The second portions 15Ab connect the inner circumferences of the plurality of first portions 15Aa. The third portion 15Ac is an annular member that connects the outer circumferences of the plurality of first portions 15Aa. An opening 15Ad is provided in the region enclosed by the plurality of first portions 15Aa, the second portion 15Ab, and the third portion 15Ac.

[0095] The insulating plate 16 has a plurality of first portions 16a, a second portion 16b, and a third portion 16c. Each of the plurality of first portions 16a extends radially and is arranged to overlap with the plurality of first portions 15Aa of the conductive member 15A. The second portion 16b connects the inner circumferences of the plurality of first portions 16a. The third portion 16c is an annular member that connects the outer circumferences of the plurality of first portions 16a. An opening 16d is provided in the region enclosed by the plurality of first portions 16a, the second portion 16b, and the third portion 16c.

[0096] The insulating plate 16 insulates the conductive member 14A from the conductive member 15A. In addition, multiple first portions 14Aa of the conductive member 14A can be electrically connected to multiple first connection portions 210s through the opening 15Ad of the conductive member 15A and the opening 16d of the insulating plate 16.

[0097] The conductive member 14A is electrically connected to the lid portion 22 by a method such as welding. The conductive member 15A is electrically connected to the main body portion 21 by a method such as welding.

[0098] With the above configuration, in a configuration in which a plurality of first connection portions 210s and a plurality of second connection portions 210t are arranged along the radial direction of the electrode body 10E, the plurality of first connection portions 210s are electrically connected to the conductive member 14A, and the plurality of second connection portions 210t are electrically connected to the conductive member 15A.

[0099] It should be noted that the configurations of the conductive members 14A, 15A and the insulating plate 16 are merely examples, and the electrical connections between the multiple first connection parts 210s and multiple second connection parts 210t and the main body part 21 and the lid part 22 may be configured in any way. Furthermore, the configuration of the second embodiment can be combined with the first to fifth modified examples described above.

[0100] (Third Embodiment) Figure 17 is a schematic plan view showing the arrangement of a plurality of first connection parts and a plurality of second connection parts in a secondary battery according to the third embodiment. Figure 18 is a cross-sectional view showing an example of the connection configuration between the plurality of first connection parts and a plurality of second connection parts and an external terminal in a secondary battery according to the third embodiment. Figure 19 is a plan view of the electrode body according to the third embodiment, as seen from the negative electrode active material layer side when it is unfolded. Figure 20 is a plan view of the electrode body according to the third embodiment, as seen from the positive electrode active material layer side when it is unfolded.

[0101] Unlike the first embodiment, the second embodiment and their respective modifications described above, the secondary battery 1B according to the third embodiment has no negative electrode current collectors 213 in the plurality of first connection portions 210s, and no positive electrode current collectors 212 in the plurality of second connection portions 210t.

[0102] As shown in Figure 17, in a plan view from direction C along the winding central axis, the wound electrode body 10F is divided into a region where multiple first connection portions 210s are provided and a region where multiple second connection portions 210t are provided. In Figure 17, the region where multiple first connection portions 210s are provided and the region where multiple second connection portions 210t are provided are schematically shown with different hatching.

[0103] The region where multiple first connection portions 210s are provided is located on the right side of the electrode body 10F. The region where multiple second connection portions 210t are provided is located on the left side of the electrode body 10F. Region B between the region where multiple first connection portions 210s are provided and the region where multiple second connection portions 210t are provided is a region where neither multiple first connection portions 210s nor multiple second connection portions 210t are provided, and is not connected to the conductive members 14 and 15.

[0104] As shown in Figure 18, each of the multiple first connection portions 210s is constructed by laminating an insulating film 211 (insulating film protrusion 211t) and a positive electrode current collector 212 (positive electrode current collector protrusion 212t). The positive electrode current collector protrusion 212t is laminated on the first main surface 211a of the insulating film protrusion 211t. In addition, in the multiple first connection portions 210s, the second main surface 211b of the insulating film protrusion 211t does not have a negative electrode current collector 213 (negative electrode current collector protrusion 213t). In the multiple first connection portions 210s, the second main surface 211b of the insulating film protrusion 211t is exposed from the negative electrode current collector 213.

[0105] Similarly, each of the multiple second connection portions 210t is constructed by laminating an insulating film 211 (insulating film protrusion 211t) and a negative electrode current collector 213 (negative electrode current collector protrusion 213t). The negative electrode current collector protrusion 213t is laminated on the second main surface 211b of the insulating film protrusion 211t. Furthermore, in the multiple second connection portions 210t, the first main surface 211a of the insulating film protrusion 211t does not have a positive electrode current collector 212 (positive electrode current collector protrusion 212t). In the multiple second connection portions 210t, the first main surface 211a of the insulating film protrusion 211t is exposed from the positive electrode current collector 212.

[0106] As shown in Figure 19, a negative electrode current collector 213 (negative electrode conductive layer 213b (see Figure 3)) is formed in the region where multiple second connection portions 210t are provided on the outer circumferential surface side of the electrode body 10F where the negative electrode active material layer 230 is provided. A negative electrode current collector 213 (negative electrode conductive layer 213b (see Figure 3)) is not formed in the region where multiple first connection portions 210s are provided.

[0107] As shown in Figure 20, a positive electrode current collector 212 (positive electrode conductive layer 212b (see Figure 3)) is formed in the region where a plurality of first connection portions 210s are provided on the inner circumferential surface side of the electrode body 10F where the positive electrode active material layer 220 is provided. A positive electrode current collector 212 (positive electrode conductive layer 212b (see Figure 3)) is not formed in the region where a plurality of second connection portions 210t are provided. In this embodiment, the positive electrode current collector 212 and the negative electrode current collector 213 can be formed, for example, by plating.

[0108] In the third embodiment as well, the plurality of first connection portions 210s and the plurality of second connection portions 210t are provided on the same side of the wound electrode body 10 in the C direction along the rotational axis. The lower end side of the wound electrode body 10F (the bottom side of the main body portion 21 shown in Figure 1) does not have a connection configuration to an external terminal. As a result, the overall volume of the electrode body 10F, including the connection portions, can be reduced compared to a configuration in which connection portions are provided at both ends of the wound electrode body 10F. Therefore, the secondary battery 1B of this embodiment can improve the volumetric energy density.

[0109] (Fifth Modification) Figure 21 is a schematic cross-sectional view showing the connection configuration between the multiple first connection parts and the multiple second connection parts and the external terminal in the electrode body according to the fifth modification. As shown in Figure 21, in the electrode body 10G according to the fifth modification, unlike the third embodiment described above, the multiple first connection parts 210s are bent multiple times in the wound electrode body 10G.

[0110] The insulating film protrusions 211t and positive electrode current collector protrusions 212t of the multiple first connection portions 210s are bent radially inward at a position close to the side surface (top surface in Figure 21) of the positive electrode active material layer 220B and the negative electrode active material layer 230. Furthermore, the insulating film protrusions 211t and positive electrode current collector protrusions 212t of the multiple first connection portions 210s are bent radially outward.

[0111] As a result, even if the wound electrode body 10G has a configuration in which multiple first connecting portions 210s are bent, the length of the portion of the outermost first connecting portion 210s that protrudes radially outward can be suppressed. As a result, the overall volume of the electrode body 10G can be reduced, and the volumetric energy density can be improved.

[0112] Furthermore, the configuration of the fifth modified example can be combined with the first embodiment, the second embodiment, and each of their modified examples described above.

[0113] As a variation of the above-described embodiment, for example, the insulating film 211, which is a porous material, may be a two-layer insulating film. In that case, (in addition to the originally intended insulating film) a porous film containing at least one of inorganic particles or organic particles with higher heat resistance than the polymer layer of the current collector assembly 210 is further provided. PVDF can be used as the material for the porous film. With this configuration, even if a short circuit occurs between the Cu porous film and the Al porous film, a chain reaction of short-circuit expansion due to melting of the polymer porous film can be prevented.

[0114] 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.

[0115] 1, 1A, 1B Secondary battery 10, 10A, 10B, 10C, 10D, 10E, 10F, 10G Electrode body 20 Housing 14, 14A, 15, 15A Conductive member 16 Insulating plate 210, 210A, 210B, 210C, 210D, 210E Current collector assembly 211 Insulating film 211s Main part of insulating film 211t Protruding part of insulating film 212 Positive electrode current collector 212a Positive electrode porous body 212b Positive electrode conductive layer 212s Main part of positive electrode current collector 212t Protruding part of positive electrode current collector 213 Negative electrode current collector 213a Negative electrode porous body 213b Negative electrode conductive layer 213s Main part of negative electrode current collector 213t Protruding part of negative electrode current collector 220 Positive electrode active material layer 230 Negative electrode active material layer 240 Separator

Claims

1. A secondary battery comprising: 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 and is 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 and is 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 constructed 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; the wound electrode body has a plurality of first connection parts which are electrically connected to an external positive electrode terminal, and a plurality of second connection parts which are electrically connected to an external negative electrode terminal; the plurality of first connection parts and the plurality of second connection parts are provided on the outer edge on the same side in the direction along the rotational axis of the wound electrode body, and are arranged apart from each other in the winding direction of the electrode body.

2. The secondary battery according to claim 1, wherein the outer edge of the electrode body in a direction along the rotational axis is provided with a plurality of slits or a plurality of notches, and the plurality of first connection portions and the plurality of second connection portions are separated in the winding direction of the electrode body by the plurality of slits or a plurality of notches.

3. The secondary battery according to claim 1 or claim 2, wherein the plurality of first connecting portions and the plurality of second connecting portions are bent in different directions in the thickness direction of the electrode body.

4. The secondary battery according to any one of claims 1 to 3, wherein in the wound electrode body, the region where the plurality of first connection portions are provided and the region where the plurality of second connection portions are provided are arranged separately with respect to the rotational axis of the electrode body.

5. The secondary battery according to any one of claims 1 to 3, wherein the plurality of first connection parts and the plurality of second connection parts are each arranged along the radial direction of the electrode body.

6. The secondary battery according to any one of claims 1 to 5, wherein the plurality of first connection portions and the plurality of second connection portions are each formed from portions of the positive electrode current collector, the insulating film, and the negative electrode current collector that protrude from the side surfaces of the positive electrode active material layer and the negative electrode active material layer, and the positive electrode current collector, the insulating film, and the negative electrode current collector are laminated together.

7. The secondary battery according to any one of claims 1 to 5, wherein each of the plurality of first connection portions is formed from portions of the positive electrode current collector and the insulating film that protrude from the side surfaces of the positive electrode active material layer and the negative electrode active material layer, and the insulating film and the positive electrode current collector are laminated together, and the negative electrode current collector is not provided on the second main surface of the insulating film in the plurality of first connection portions, and each of the plurality of second connection portions is formed from portions of the insulating film and the negative electrode current collector that protrude from the side surfaces of the positive electrode active material layer and the negative electrode active material layer, and the insulating film and the negative electrode current collector are laminated together, and the positive electrode current collector is not provided on the first main surface of the insulating film in the plurality of second connection portions.

8. The secondary battery according to claim 6 or 7, wherein each of the plurality of first connection portions includes a first insulating layer provided on the side of the insulating film opposite to the positive electrode current collector, and each of the plurality of second connection portions includes a second insulating layer provided on the side of the insulating film opposite to the negative electrode current collector.

9. The secondary battery according to any one of claims 1 to 8, wherein the plurality of first connecting portions and the plurality of second connecting portions are arranged separately along the winding direction of the electrode body by a plurality of slits provided on the outer edge in a direction along the rotational axis of the electrode body, and openings with a width larger than the plurality of slits are formed at the ends of the plurality of slits in a direction away from the outer edge of the electrode body.

10. The secondary battery according to any one of claims 1 to 7, wherein the plurality of first connecting portions and the plurality of second connecting portions are separated along the winding direction of the electrode body by a plurality of slits provided on the outer edge in a direction along the rotational axis of the electrode body, and the plurality of slits have an insulating layer that covers the ends of the plurality of slits in a direction away from the outer edge of the electrode body and extends along the winding direction of the electrode body.

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