Secondary battery

Abstract

Provided is a technology for improving the usefulness of a lithium secondary battery. A secondary battery Ba according to one aspect of the present disclosure includes: a first electrode sheet (a clad electrode 1); and a second electrode sheet (a single metal layer electrode 2) which has the same polarity as that of the first electrode sheet (the clad electrode 1). The first electrode sheet (the clad electrode 1) includes a first current collector (a clad current collector 10) which has a resin layer 100 and a pair of metal layers 102a, 102b that are provided on both surfaces of the resin layer 100, and which has a first end part (a clad end part 120) where the pair of metal layers 102a, 102b are exposed. The second electrode sheet (the single metal layer electrode 2) includes a second current collector (a single layer current collector 20) which includes a metal and does not include the resin layer 100, and which has a second end part (a single layer end part 220) where the metal is exposed. The first end part (the clad end part 120) and the second end part (the single layer end part 220) are stacked and joined to each other.

Description

Secondary battery

[0001] SUMMARY OF THE INVENTION An exemplary embodiment of the present disclosure relates to a secondary battery.

[0002] In recent years, technology for converting natural energy such as solar or wind power into electrical energy has been attracting attention. Accordingly, various secondary batteries have been developed as electricity storage devices that are highly safe and capable of storing a large amount of electrical energy.

[0003] Among them, lithium secondary batteries, which are charged and discharged by the movement of lithium ions between a positive electrode and a negative electrode, are known to exhibit high voltage and high energy density. A typical lithium secondary battery is a lithium ion secondary battery (LIB), whose positive and negative electrodes have active materials for retaining lithium elements. In a lithium ion secondary battery, charging and discharging are performed by the exchange of lithium ions between the positive electrode active material and the negative electrode active material.

[0004] Furthermore, current collectors have been developed to improve the safety of lithium-ion secondary batteries. For example, Patent Document 1 discloses a lithium-ion secondary battery that aims to provide a positive and negative electrode configuration that prevents ignition in the event of abnormal heat generation during overcharge or at high temperatures, while maintaining electrical resistance at the same level as conventional batteries.

[0005] Japanese Patent Application Publication No. 11-102711

[0006] The present disclosure provides a technique for improving the usefulness of secondary batteries.

[0007] In one exemplary embodiment of the present disclosure, there is provided a secondary battery including a first electrode sheet and a second electrode sheet having the same polarity as the first electrode sheet, wherein the first electrode sheet includes a first current collector having a resin layer and a pair of metal layers provided on each of both surfaces of the resin layer, the first current collector having a first end where the pair of metal layers are exposed, and the second electrode sheet includes a second current collector comprising a metal and not a resin layer, the second current collector having a second end where the metal is exposed, and the first end and the second end are stacked and joined together.

[0008] According to one exemplary embodiment of the present disclosure, a technique for improving the usefulness of a secondary battery can be provided.

[0009] FIG. 1 is a diagram for explaining a configuration example of a clad electrode 1. FIG. 2 is a diagram for explaining a configuration example of a single metal layer electrode 2. FIG. 3 is a diagram for explaining a configuration example of a secondary battery Ba. FIG. 4 is a diagram for explaining a configuration example of a secondary battery Ba. FIG. 5 is a diagram for explaining a configuration example of a secondary battery Ba. FIG. 6 is a reference diagram for explaining the function of a bonding mark w.

[0010] Hereinafter, each embodiment of the present disclosure will be described.

[0011] In one exemplary embodiment, there is provided a secondary battery including a first electrode sheet and a second electrode sheet having the same polarity as the first electrode sheet, wherein the first electrode sheet includes a first current collector having a resin layer and a pair of metal layers provided on each of both sides of the resin layer, the first current collector having a first end where the pair of metal layers are exposed, and the second electrode sheet includes a second current collector comprising a metal and not a resin layer, the second current collector having a second end where the metal is exposed, and the first end and the second end are stacked and joined together.

[0012] In one exemplary embodiment, the first electrode sheet includes a first active material layer containing an active material, the first active material layer being provided on at least one surface of a first current collector, and the second electrode sheet includes a second active material layer containing an active material, the second active material layer being provided on at least one surface of a second current collector.

[0013] In one exemplary embodiment, the basis weight of the first active material layer of the first electrode sheet is less than the basis weight of the second active material layer of the second electrode sheet.

[0014] In one exemplary embodiment, the area of ​​the first end is greater than the area of ​​the second end.

[0015] In one exemplary embodiment, the first end and the second end have bonding marks recessed from one side to the other in the stacking direction.

[0016] In one exemplary embodiment, the thickness of the metal layer on one side of the resin layer is greater than the thickness of the metal layer on the other side of the resin layer.

[0017] In one exemplary embodiment, the bond marks are weld marks.

[0018] In one exemplary embodiment, the electrode assembly includes a plurality of first electrode sheets and a plurality of second electrode sheets.

[0019] In one exemplary embodiment, one first end and one second end are stacked one on top of the other.

[0020] In one exemplary embodiment, a plurality of second end portions are stacked between a plurality of first end portions.

[0021] In one exemplary embodiment, the number of second electrode sheets is equal to or greater than 1 / 4 and equal to or less than 3 / 4 of the number of first electrode sheets.

[0022] In one exemplary embodiment, the thickness of each of the pair of metal layers is 0.3 μm or greater.

[0023] In one exemplary embodiment, the thickness of the second current collector is 4 μm or greater.

[0024] In one exemplary embodiment, the thickness of each of the pair of metal layers is 1 / 30 or more of the thickness of the second current collector.

[0025] In one exemplary embodiment, the thickness of each of the pair of metal layers is equal to or less than half the thickness of the second current collector.

[0026] In one exemplary embodiment, the first electrode sheet and the second electrode sheet are positive electrode sheets.

[0027] In one exemplary embodiment, the pair of metal layers and the second current collector comprise aluminum.

[0028] In one exemplary embodiment, the first electrode sheet and the second electrode sheet are negative electrode sheets.

[0029] In one exemplary embodiment, the pair of metal layers and the second current collector comprise copper.

[0030] In one exemplary embodiment, the first electrode sheet and the second electrode sheet are substantially free of negative electrode active material.

[0031] Hereinafter, each embodiment of the present disclosure will be described in detail with reference to the drawings. In each drawing, the same or similar elements are designated by the same reference numerals, and redundant explanations will be omitted. Unless otherwise specified, the positional relationships, such as up, down, left, and right, will be described based on the positional relationships shown in the drawings. The dimensional ratios in the drawings do not represent actual ratios, and the actual ratios are not limited to the ratios shown in the drawings.

[0032] In the present disclosure, the usefulness of a secondary battery includes at least some of the energy density, safety, monetary cost required for manufacturing, and manufacturing efficiency of the secondary battery.

[0033] Furthermore, in this disclosure, the secondary battery Ba is typically described as a lithium ion secondary battery, but the present disclosure is also applicable to other types of secondary batteries.

[0034] 1. Configuration Examples of Clad Electrode 1 and Single Metal Layer Electrode 2 Fig. 1 is a diagram for explaining a configuration example of a clad electrode 1 according to the present disclosure. Fig. 2 is a diagram for explaining a configuration example of a single metal layer electrode 2.

[0035] 1 is a three-dimensional perspective view illustrating an example of the configuration of the clad electrode 1. In one embodiment, the clad electrode 1 is a sheet-like electrode along the xz plane. The clad electrode 1 includes a clad current collector 10 and a pair of active material layers 12 a, 12 b.

[0036] Clad current collector 10 The clad current collector 10 includes a resin layer 100 and a pair of metal layers 102a, 102b. A portion of the clad current collector 10 is exposed from the pair of metal layers 102a, 102b as a clad end portion 120.

[0037] (Resin Layer 100) The resin layer 100 may be made of, for example, a sheet-like (film-like) or fibrous resin. The resin may be, for example, a thermoplastic resin such as polyethylene terephthalate (PET), polyethylene, polypropylene, polyamide, or polyvinyl chloride. The resin layer 100 may be made by laminating at least one or more of the resins. In one embodiment, the resin layer 100 is made of a resin having a melting point of 130°C or higher and 300°C or lower. In one embodiment, the average thickness of the resin layer 100 may be 2 μm or higher and 15 μm or lower, or 3 μm or higher and 10 μm or lower.

[0038] (Pair of Metal Layers 102a, 102b) The pair of metal layers 102a, 102b are provided on both sides of the resin layer 100. Specifically, the metal layer 102a is provided on the surface of the resin layer 100 facing in the positive y-axis direction, and the metal layer 102b is provided on the surface of the resin layer 100 facing in the negative y-axis direction.

[0039] The pair of metal layers 102a, 102b are made of a conductor that does not react with lithium ions or has a sufficiently low reactivity. In one embodiment, the pair of metal layers 102a, 102b are made of a common type of metal. In one embodiment, the pair of metal layers 102a, 102b are made of at least one material selected from the group consisting of aluminum, copper, titanium, stainless steel, nickel, and alloys thereof. In one embodiment, the pair of metal layers 102a, 102b are formed by vapor deposition, sputtering, electrolytic plating, or lamination of the above material on the surface of the resin layer 100. In one embodiment, the average thickness of each of the pair of metal layers 102a, 102b may be 0.3 μm to 15 μm, 0.5 μm to 12 μm, 2.0 μm to 10 μm, or 3.0 μm to 6.0 μm.

[0040] In this disclosure, "clad" does not only refer to metals directly bonded (joined) to each other, but also includes metals bonded (joined) to each other with a resin layer interposed therebetween, such as clad current collector 10.

[0041] (Clad end portion 120) The clad end portion 120 includes a portion of the clad current collector 10 where the pair of metal layers 102 a, 102 b are exposed. The clad end portion 120 can also be said to be a portion of the clad current collector 10 where no active material is provided. The clad end portion 120 is a part of the clad current collector 10, and like the clad current collector 10, includes the resin layer 100 and the pair of metal layers 102 a, 102 b provided on both sides of the resin layer 100.

[0042] Pair of Active Material Layers 12a, 12b The pair of active material layers 12a, 12b of the clad electrode 1 are provided on both sides of the clad current collector 10. Specifically, the active material layer 12a is provided on the surface of the clad current collector 10 facing in the positive direction of the y axis, and the active material layer 12b is provided on the surface of the clad current collector 10 facing in the negative direction of the y axis. In one embodiment, the pair of active material layers 12a, 12b of the clad electrode 1 are composed of the same composition. For example, when the active material layer 12a is composed of a positive electrode active material, the active material layer 12b is also composed of a positive electrode active material. Furthermore, when the active material layer 12a is composed of a negative electrode active material, the active material layer 12b is also composed of a negative electrode active material. The pair of active material layers 12 a , 12 b of the clad electrode 1 being provided on both sides of the clad current collector 10 can also be said to be coated on both sides of the clad current collector 10 .

[0043] [Single-metal layer electrode 2] Fig. 2 is a three-dimensional perspective view illustrating an example of the configuration of the single-metal layer electrode 2. The single-metal layer electrode 2 is a sheet-like electrode along the xz plane. The single-metal layer electrode 2 includes a single-layer current collector 20 and a pair of active material layers 22a, 22b.

[0044] - Single-layer current collector 20 - The single-layer current collector 20 contains a metal. Unlike the clad current collector 10 of the clad electrode 1, the single-layer current collector 20 does not include a resin layer. Like the pair of metal layers 102a, 102b of the clad electrode 1, the single-layer current collector 20 is made of a conductor that does not react with lithium ions or has sufficiently low reactivity with lithium ions. In one embodiment, the single-layer current collector 20 is made of at least one material selected from the group consisting of aluminum, copper, titanium, stainless steel, nickel, and alloys thereof. In one embodiment, the average thickness of the single-layer current collector 20 may be 4 μm or more and 30 μm or less, 5 μm or more and 25 μm or less, 7 μm or more and 20 μm or less, or 10 μm or more and 15 μm or less.

[0045] In one embodiment, the average thickness of the single-layer current collector 20 is 30 times or less the average thickness of each of the pair of metal layers 102a, 102b of the clad current collector 10. That is, in one embodiment, the average thickness of each of the pair of metal layers 102a, 102b of the clad current collector 10 is 1 / 30 or more the average thickness of the single-layer current collector 20.

[0046] In one embodiment, the average thickness of the single-layer current collector 20 is at least twice the average thickness of each of the pair of metal layers 102 a, 102 b of the clad current collector 10. That is, in one embodiment, the average thickness of each of the pair of metal layers 102 a, 102 b of the clad current collector 10 is no more than half the average thickness of the single-layer current collector 20.

[0047] In one embodiment, the average thickness of the single-layer current collector 20 is at least two times and at most 30 times the average thickness of each of the pair of metal layers 102 a, 102 b of the clad current collector 10. That is, in one embodiment, the average thickness of each of the pair of metal layers 102 a, 102 b of the clad current collector 10 is at least 1 / 30 and at most 1 / 2 of the average thickness of the single-layer current collector 20.

[0048] (Single-layer end 220) The single-layer current collector 20 includes a single-layer end 220 where the metal is exposed. The single-layer end 220 can also be referred to as a portion of the single-layer current collector 20 where no active material is provided. In one embodiment, the area of ​​the surface of the single-layer end 220 parallel to the xz plane is smaller than the area of ​​the surface of the cladding end 120 parallel to the xz plane. In other words, the area of ​​the single-layer end 220 when viewed from the positive y-axis direction toward the negative y-axis direction is smaller than the area of ​​the cladding end 120 when viewed from the positive y-axis direction toward the negative y-axis direction.

[0049] Pair of Active Material Layers 22a, 22b The pair of active material layers 22a, 22b included in the single-metal layer electrode 2 are provided on both sides of the single-layer current collector 20. Specifically, the active material layer 22a is provided in the positive direction of the y-axis of the single-layer current collector 20, and the active material layer 22b is provided in the negative direction of the y-axis of the single-layer current collector 20. In one embodiment, the pair of active material layers 22a, 22b included in the single-metal layer electrode 2 are composed of the same composition. For example, if the active material layer 22a is composed of a positive electrode active material, the active material layer 22b is also composed of a positive electrode active material. Alternatively, for example, if the active material layer 22a is composed of a negative electrode active material, the active material layer 22b is also composed of a negative electrode active material. The pair of active material layers 22a, 22b included in the single metal layer electrode 2 are provided on both sides of the single layer current collector 20, which can also be said to mean that the pair of active material layers 22a, 22b are coated on both sides of the single layer current collector 20.

[0050] In one embodiment, the basis weight of the active material in the pair of active material layers 22 a, 22 b of the single metal layer electrode 2 is greater than the basis weight of the active material in the pair of active material layers 12 a, 12 b of the clad electrode 1. In other words, the single metal layer electrode 2 may be provided with more active material per unit area than the clad electrode 1.

[0051] [Clad Positive Electrode 1p / Clad Negative Electrode 1n] The above-described clad electrode 1 can be used as either a positive electrode or a negative electrode by appropriately selecting the composition of the pair of active material layers 12a, 12b and the type of metal of the pair of metal layers 102a, 102b of the clad current collector 10. Hereinafter, the clad electrode 1 serving as a positive electrode will be referred to as a "clad positive electrode 1p," and the clad electrode 1 serving as a negative electrode will be referred to as a "clad negative electrode 1n."

[0052] Specifically, in the clad electrode 1, a positive electrode active material is used as the active material of the pair of active material layers 12a, 12b, and aluminum, for example, is used as the metal of the pair of metal layers 102a, 102b, so that the clad electrode 1 can be used as a clad positive electrode 1p. Hereinafter, the pair of active material layers 12a, 12b containing a positive electrode active material as the active material will be referred to as a "pair of positive electrode active material layers 12pa, 12pb." Hereinafter, the pair of metal layers 102a, 102b containing a positive electrode metal such as aluminum will be referred to as a "pair of positive electrode metal layers 102pa, 102pb." Hereinafter, the clad current collector 10 composed of the resin layer 100 and the pair of positive electrode metal layers 102pa, 102pb will be referred to as a "clad positive electrode current collector 10p." In the following description, the portion of the clad positive electrode current collector 10p that corresponds to the clad end portion 120 will be referred to as the "clad positive electrode end portion 120p."

[0053] Furthermore, in the clad electrode 1, by using a negative electrode active material as the active material of the pair of active material layers 12a, 12b and using, for example, copper as the metal of the pair of metal layers 102a, 102b, the clad electrode 1 can be used as a clad negative electrode 1n. Hereinafter, the pair of active material layers 12a, 12b containing a negative electrode active material as the active material will be referred to as the "pair of negative electrode active material layers 12na, 12nb." Hereinafter, the pair of metal layers 102a, 102b containing a negative electrode metal such as copper will be referred to as the "pair of negative electrode metal layers 102na, 102nb." Hereinafter, the clad current collector 10 composed of the resin layer 100 and the pair of negative electrode metal layers 102na, 102nb will be referred to as the "clad negative electrode current collector 10n." In the following description, the portion of the clad negative electrode current collector 10n that corresponds to the clad end portion 120 will be referred to as the "clad negative electrode end portion 120n."

[0054] (Configuration example of a pair of positive electrode active material layers 12pa, 12pb) The positive electrode active material is a material for holding a carrier metal in the electrode, and can also be called a host material for the carrier metal. The positive electrode active material may be a material for holding lithium ions in the electrode, in which case lithium ions are loaded into and deloaded from the positive electrode active material by charging and discharging the battery. This can improve the stability and output voltage of the battery. In one embodiment, the positive electrode active material is a metal oxide or a metal phosphate. The metal oxide may be, for example, a cobalt oxide-based compound, a manganese oxide-based compound, or a nickel oxide-based compound. The metal phosphate may be, for example, an iron phosphate-based compound or a cobalt phosphate-based compound. In one embodiment, the positive electrode active material is LiCoO ２ , LiNi ｘ Co ｙ Mn ｚ O(x+y+z=1), LiNi ｘ Co ｙ Al ｚ O(x+y+z=1), LiNi ｘ Mn ｙ O(x+y=1), LiNiO ２ , LiMn ２ O ４ , LiFePO, LiCoPO, LiFeOF, LiNiOF, and LiTiS ２ The positive electrode active material may be at least one selected from the group consisting of: a) a positive electrode active material layer (12pa, 12pb) containing at least one positive electrode active material ...

[0055] In one embodiment, at least one of the pair of positive electrode active material layers 12pa, 12pb may contain one or more components other than the positive electrode active material.

[0056] In one embodiment, at least one of the pair of positive electrode active material layers 12pa, 12pb may include a sacrificial positive electrode material. The sacrificial positive electrode material is a lithium-containing compound that undergoes an oxidation reaction and does not substantially undergo a reduction reaction in the charge / discharge potential range of the positive electrode active material.

[0057] In one embodiment, at least one of the pair of positive electrode active material layers 12pa, 12pb may contain a gel electrolyte. The gel electrolyte may improve the adhesive strength between the pair of positive electrode active material layers 12pa, 12pb and the clad positive electrode current collector 10p. In one example, the gel electrolyte includes a polymer, an organic solvent, and a lithium salt. The polymer in the gel electrolyte may be, for example, a copolymer of polyethylene and / or polyethylene oxide, polyvinylidene fluoride, or a copolymer of polyvinylidene fluoride and hexafluoropropylene.

[0058] In one embodiment, at least one of the pair of positive electrode active material layers 12pa, 12pb may include a conductive additive and / or a binder. In one example, the conductive additive is carbon black, single-walled carbon nanotubes (SWCNT), multi-walled carbon nanotubes (MWCNT), carbon nanofibers (CNF), or the like. In one example, the binder is polyvinylidene fluoride, polytetrafluoroethylene, styrene butadiene rubber, acrylic resin, polyimide resin, or the like. In one embodiment, the content of the conductive additive is 0.5% by mass to 30% by mass or less of the pair of positive electrode active material layers 12pa, 12pb as a whole. In one embodiment, the content of the binder may be 0.5% by mass to 30% by mass or less of the pair of positive electrode active material layers 12pa, 12pb as a whole.

[0059] In one embodiment, at least one of the pair of positive electrode active material layers 12pa, 12pb may contain a polymer electrolyte. For example, the polymer electrolyte may be a solid polymer electrolyte primarily containing a polymer and an electrolyte, or a semi-solid polymer electrolyte primarily containing a polymer, an electrolyte, and a plasticizer. In one embodiment, the total content of the polymer electrolyte may be 0.5% by mass to 30% by mass or less, based on the total content of the pair of positive electrode active material layers 12pa, 12pb.

[0060] (Configuration example of a pair of negative electrode active material layers 12na, 12nb) The negative electrode active material is a material that causes an electrode reaction, i.e., an oxidation reaction and a reduction reaction, at the negative electrode. The negative electrode active material may be, for example, lithium metal and an alloy containing lithium metal, a carbon-based material, a metal oxide, a metal that alloys with lithium, and an alloy containing the metal. The carbon-based material may be, for example, graphene, graphite, hard carbon, carbon nanotubes, etc. The metal oxide may be, for example, a titanium oxide-based compound, a cobalt oxide-based compound, etc. The metal that alloys with lithium may be, for example, silicon, germanium, tin, lead, aluminum, and gallium.

[0061] In one embodiment, at least one of the pair of negative electrode active material layers 12na, 12nb may contain a gel electrolyte. The gel electrolyte may improve the adhesive strength between the pair of negative electrode active material layers 12na, 12nb and the clad negative electrode current collector 10n. In one example, the gel electrolyte includes a polymer, an organic solvent, and a lithium salt. The polymer in the gel electrolyte may be, for example, a copolymer of polyethylene and / or polyethylene oxide, polyvinylidene fluoride, or a copolymer of polyvinylidene fluoride and hexafluoropropylene.

[0062] In one embodiment, at least one of the pair of negative electrode active material layers 12na, 12nb may contain a binder. For example, the binder may be polyvinylidene fluoride, polytetrafluoroethylene, styrene butadiene rubber, an acrylic resin, a polyimide resin, or the like. In one embodiment, the content of the conductive additive is 0.5% by mass to 30% by mass or less with respect to the entire pair of negative electrode active material layers 12na, 12nb. In one embodiment, the content of the binder may be 0.5% by mass to 30% by mass or less with respect to the entire pair of negative electrode active material layers 12na, 12nb.

[0063] In one embodiment, at least one of the pair of negative electrode active material layers 12na, 12nb may contain a polymer electrolyte. For example, the polymer electrolyte may be a solid polymer electrolyte primarily containing a polymer and an electrolyte, or a semi-solid polymer electrolyte primarily containing a polymer, an electrolyte, and a plasticizer. In one embodiment, the total content of the polymer electrolyte may be 0.5% by mass to 30% by mass or less with respect to the entire pair of negative electrode active material layers 12na, 12nb.

[0064] [Single-metal layer positive electrode 2p / single-metal layer negative electrode 2n] The above-described single-metal layer electrode 2 can be used as either a positive electrode or a negative electrode by appropriately selecting the composition of the pair of active material layers 22a, 22b and the type of metal constituting the single-layer current collector 20. Hereinafter, the single-metal layer electrode 2 serving as a positive electrode will be referred to as a "single-metal layer positive electrode 2p," and the single-metal layer electrode 2 serving as a negative electrode will be referred to as a "single-metal layer negative electrode 2n."

[0065] Specifically, in the single-metal layer electrode 2, a positive electrode active material is used as the active material of the pair of active material layers 22a, 22b, and aluminum, for example, is used as the metal constituting the single-layer current collector 20, thereby enabling the single-metal layer electrode 2 to be used as a single-metal layer positive electrode 2p. Hereinafter, the pair of active material layers 22a, 22b containing a positive electrode active material as the active material will be referred to as a "pair of positive electrode active material layers 22pa, 22pb." Hereinafter, the single-layer current collector 20 containing a metal for a positive electrode, such as aluminum, will be referred to as a "single-layer positive electrode current collector 20p." Hereinafter, the portion of the single-layer positive electrode current collector 20p corresponding to the single-layer end portion 220 will be referred to as a "single-layer positive electrode end portion 220p."

[0066] Furthermore, in the single-metal layer electrode 2, by using a negative electrode active material as the active material of the pair of active material layers 22a, 22b and using, for example, copper as the metal constituting the single-layer current collector 20, the single-metal layer electrode 2 can be used as a single-metal layer negative electrode 2n. Hereinafter, the pair of active material layers 22a, 22b containing a negative electrode active material as the active material will be referred to as a "pair of negative electrode active material layers 22na, 22nb." Hereinafter, the single-layer current collector 20 containing a metal for a negative electrode, such as copper, will be referred to as a "single-layer negative electrode current collector 20n." Hereinafter, the portion of the single-layer negative electrode current collector 20n corresponding to the single-layer end portion 220 will be referred to as a "single-layer negative electrode end portion 220n."

[0067] The pair of positive electrode active material layers 22pa, 22pb of the single-metal layer positive electrode 2p may have a common structure with the pair of positive electrode active material layers 12pa, 12pb of the clad positive electrode 1p. Also, the pair of negative electrode active material layers 22na, 22nb of the single-metal layer negative electrode 2n may have a common structure with the pair of negative electrode active material layers 12na, 12nb of the clad negative electrode 1n.

[0068] 2. Configuration Example of Secondary Battery Ba [Stacking of Clad Electrode 1 and Single Metal Layer Electrode 2] Figures 3 to 6 are diagrams for explaining a configuration example of a secondary battery Ba. Hereinafter, with reference to Figures 3 to 6, a configuration example of a secondary battery Ba using the above-mentioned clad electrode 1 and single metal layer electrode 2 will be described.

[0069] Fig. 3 is a cross-sectional view parallel to the xy plane of a secondary battery Ba constructed by stacking multiple clad electrodes 1 and multiple single-metal-layer electrodes 2. Specifically, the secondary battery Ba in Fig. 3 is constructed by periodically stacking, in order from the positive y-axis direction, (1) single-metal-layer positive electrodes 2p, (2) single-metal-layer negative electrodes 2n, (3) clad positive electrodes 1p, and (4) clad negative electrodes 1n. Note that Fig. 3 shows only a portion of the stack of the secondary battery Ba, and the number of each electrode may be greater than or equal to the number shown in Fig. 3. Below, the above (1) to (4) will be described in order.

[0070] (1) First, a single-metal layer positive electrode 2p is provided at the end in the positive y-axis direction in Fig. 3. The single-metal layer positive electrode 2p is configured by stacking, in order from the positive y-axis direction, a positive electrode active material layer 22pa, a single-layer positive electrode current collector 20p, and a positive electrode active material layer 22pb. Of these, the single-layer positive electrode current collector 20p includes a single-layer positive electrode end portion 220p extending in the positive x-axis direction.

[0071] (2) Next, a single-metal layer negative electrode 2n is provided with a separator 30 sandwiched between it and the single-metal layer positive electrode 2p described in (1). The single-metal layer negative electrode 2n is configured by stacking, in order from the positive direction of the y-axis, a negative electrode active material layer 22na, a single-layer negative electrode current collector 20n, and a negative electrode active material layer 22nb. Of these, the single-layer negative electrode current collector 20n includes a single-layer negative electrode end portion 220n extending in the negative direction of the x-axis (i.e., in the opposite direction to the single-layer positive electrode end portion 220p). The separator 30 will be described later.

[0072] (3) Next, a clad positive electrode 1p is provided between the single-metal-layer negative electrode 2n of (2) and the clad positive electrode 1p, with a separator 30 sandwiched therebetween. The clad positive electrode 1p is configured by laminating, in order from the positive direction of the y-axis, a positive electrode active material layer 12pa, a clad positive electrode current collector 10p, and a positive electrode active material layer 12pb. Of these, the clad positive electrode current collector 10p includes a clad positive electrode end portion 120p extending in the positive direction of the x-axis (i.e., the same direction as the single-layer positive electrode end portion 220p).

[0073] (4) Next, a clad negative electrode 1n is provided on the clad positive electrode 1p of (3) with a separator 30 sandwiched therebetween. The clad negative electrode 1n is configured by laminating, in order from the positive direction of the y-axis, a negative electrode active material layer 12na, a clad negative electrode current collector 10n, and a negative electrode active material layer 12nb. Of these, the clad negative electrode current collector 10n includes a clad negative electrode end portion 120n extending in the negative direction of the x-axis (i.e., the same direction as the single-layer negative electrode end portion 220n).

[0074] In one embodiment, the secondary battery Ba is constructed by stacking the above-mentioned (1) to (4) as repeating units multiple times.

[0075] In one embodiment, the secondary battery Ba includes clad positive electrodes 1p in a number equal to, one more than, or one less than the number of single-metal layer positive electrodes 2p. In one embodiment, the secondary battery Ba includes clad negative electrodes 1n in a number equal to, one more than, or one less than the number of single-metal layer negative electrodes 2n.

[0076] [Joining of clad end 120 and single layer end 220] Figure 4 is a diagram showing a state in which, after the electrodes are stacked as in Figure 3, a plurality of single layer positive electrode end portions 220p are electrically connected to a plurality of clad positive electrode end portions 120p, and a plurality of single layer negative electrode end portions 220n are electrically connected to a plurality of clad negative electrode end portions 120n.

[0077] In one embodiment, positive electrode bonding marks Pw are formed at locations where multiple single-layer positive electrode ends 220p and multiple clad positive electrode ends 120p are bonded. In another embodiment, negative electrode bonding marks Nw are formed at locations where multiple single-layer negative electrode ends 220n and multiple clad negative electrode ends 120n are bonded. Hereinafter, when there is no need to distinguish between the positive electrode bonding marks Pw and the negative electrode bonding marks Nw, they will be collectively referred to as "bonding marks w."

[0078] In one embodiment, the joining of the plurality of single-layer positive electrode ends 220p to the plurality of clad positive electrode ends 120p and the joining of the plurality of single-layer negative electrode ends 220n to the plurality of clad negative electrode ends 120n are both performed by welding. That is, the joining marks w may be welding marks. In one embodiment, the welding is performed by ultrasonic welding.

[0079] Hereinafter, the portion of the secondary battery Ba where multiple single-layer positive electrode ends 220p and multiple clad positive electrode ends 120p are stacked will be referred to as the "positive electrode end Pe." Furthermore, the portion of the secondary battery Ba where multiple single-layer negative electrode ends 220n and multiple clad negative electrode ends 120n are stacked will be referred to as the "negative electrode end Ne." Furthermore, the portion of the secondary battery Ba where the active material layers of the clad positive electrode 1p, clad negative electrode 1n, single-metal layer positive electrode 2p, and single-metal layer negative electrode 2n and the separator 30 are stacked (i.e., the portion other than the positive electrode end Pe and the negative electrode end Ne) will be referred to as the "active material stacking region Am." The positive electrode end Pe includes a positive electrode bonding mark Pw. The negative electrode end Ne includes a negative electrode bonding mark Nw.

[0080] A user of the secondary battery Ba can charge and discharge the secondary battery Ba via the electrode tabs by joining the electrode tabs to the positive electrode end Pe and the negative electrode end Ne, respectively. At this time, at least the active material stacking region Am may be housed in a housing (pouch).

[0081] In one embodiment, the single layer positive electrode end 220p and the clad positive electrode end 120p are alternately stacked with each other at the positive electrode end Pe. Similarly, the single layer negative electrode end 220n and the clad negative electrode end 120n are alternately stacked with each other at the negative electrode end Ne.

[0082] Figure 5 is a view of the secondary battery Ba in Figure 4 when viewed from the positive y-axis direction toward the negative y-axis direction. In Figure 5, the positive electrode end Pe extends from the active material stacking region Am toward the positive x-axis direction. At the positive electrode end Pe, the area of ​​the single-layer positive electrode end 220p when viewed from the positive y-axis direction (i.e., toward the front of the paper) toward the negative y-axis direction (i.e., toward the back of the paper) is smaller than the area of ​​the clad positive electrode end 120p when viewed from the positive y-axis direction toward the negative y-axis direction. Furthermore, at the positive electrode end Pe, the positive electrode bonding mark Pw bonds the clad positive electrode end 120p and the single-layer positive electrode end 220p so as to penetrate from the positive y-axis direction toward the negative y-axis direction.

[0083] 5 , the negative electrode end Ne extends from the active material stacking region Am in the negative direction of the x-axis. At the negative electrode end Ne, the area of ​​the single-layer negative electrode end 220n when viewed from the positive y-axis (i.e., the front side of the paper) toward the negative y-axis (i.e., the back side of the paper) is smaller than the area of ​​the clad negative electrode end 120n when viewed from the positive y-axis toward the negative y-axis. At the negative electrode end Ne, the negative electrode bonding mark Nw bonds the clad negative electrode end 120n and the single-layer negative electrode end 220n so as to penetrate from the positive y-axis toward the negative y-axis.

[0084] [Details of Bonding Marks w] FIG. 6 is an enlarged cross-sectional view of the positive electrode end portion Pe, focusing on two single-layer positive electrode end portions 220p and one clad positive electrode end portion 120p sandwiched therebetween.

[0085] As shown in FIG. 7, since the resin layer 100 has insulating properties, when a plurality of single-layer positive electrode ends 220p and a plurality of clad positive electrode ends 120p are simply stacked, the single-layer positive electrode ends 220p are not electrically connected to the other single-layer positive electrode ends 220p that are provided on either side of the clad positive electrode end 120p that includes the resin layer 100.

[0086] In contrast, the two single-layer positive electrode ends 220p shown in FIG. 6 are electrically connected to each other. This is because the resin layer 100 is removed from all or at least a portion of the positive electrode bonding trace Pw when the multiple single-layer positive electrode ends 220p and the multiple clad positive electrode ends 120p are joined. For example, when the joining is performed by welding, the resin layer 100 at the positive electrode bonding trace Pw is melted and pushed aside. Alternatively, when the joining is performed by crimping, the resin layer 100 at the positive electrode bonding trace Pw is pushed aside. The formation of a resin-free area at all or at least a portion of the positive electrode bonding trace Pw results in electrical connection between the positive electrode metal layer 102pa and the positive electrode metal layer 102pb. As a result, the single-layer positive electrode end 220p in contact with the positive electrode metal layer 102pa and the single-layer positive electrode end 220p in contact with the positive electrode metal layer 102pb are also electrically connected.

[0087] 6 shows a state focusing on two single-layer positive electrode ends 220p and one clad positive electrode end 120p, but the same applies to a case where three or more single-layer positive electrode ends 220p and two or more clad positive electrode ends 120p are stacked. That is, the multiple single-layer positive electrode ends 220p and the multiple clad positive electrode ends 120p in FIG. 4 are electrically connected at the positive electrode bonding marks Pw. That is, electrical continuity of the entire positive electrode end Pe is achieved via the positive electrode bonding marks Pw.

[0088] In one embodiment, the thickness of the positive electrode metal layer 102pa provided on the surface of the resin layer 100 facing in the positive y-axis direction is different from the thickness of the positive electrode metal layer 102pb provided on the surface of the resin layer 100 facing in the negative y-axis direction. Specifically, when the positive electrode bonding mark Pw is recessed from the positive y-axis direction to the negative y-axis direction as shown in FIG. 6 , the thickness of the positive electrode metal layer 102pa is greater than the thickness of the positive electrode metal layer 102pb. That is, the positive electrode bonding mark Pw may be formed so as to recess from the thicker positive electrode metal layer 102pa toward the thinner positive electrode metal layer 102pb. Such a positive electrode bonding mark Pw may be formed, for example, by providing an anvil on the surface facing in the negative y-axis direction and applying an ultrasonic bonding horn from the positive y-axis direction. Note that the positive electrode metal layer 102pb may also be deformed for manufacturing reasons (e.g., pressure applied by an anvil corresponding to the horn).

[0089] Note that FIG. 6 is merely a conceptual diagram, and in reality, the single-layer positive electrode end portion 220p and the clad positive electrode end portion 120p are integrated at the positive electrode bonding mark Pw, and it may be difficult to distinguish the layers as shown in FIG.

[0090] Although the description in FIG. 6 focuses on the positive electrode end Pe including the positive electrode bonding trace Pw, the negative electrode end Ne including the negative electrode bonding trace Nw may also have a similar configuration.

[0091] 3. Effects A secondary battery Ba according to one embodiment of the present disclosure includes a clad electrode 1 and a single-metal layer electrode 2 having the same polarity as the clad electrode 1, and has the following configurations (1) to (3). (1) The clad electrode 1 includes a clad current collector 10 having a resin layer 100 and a pair of metal layers 102a, 102b provided on both sides of the resin layer 100. The clad current collector 10 has a clad end portion 120 at which the pair of metal layers 102a, 102b are exposed. (2) The single-metal layer electrode 2 includes a single-layer current collector 20 containing metal but not including the resin layer 100. The single-layer current collector 20 has a single-layer end portion 220 at which the metal is exposed. (3) The clad end portion 120 and the single-layer end portion 220 are stacked and joined.

[0092] If a secondary battery Ba is constructed by stacking clad electrodes 1 without using a single metal layer electrode 2 and joining the clad end portions 120 of the multiple clad electrodes 1, the resistance value at the joining marks w (i.e., the points where the multiple clad electrodes 1 are electrically connected to each other) may increase. This is because the joining marks w contain a relatively large amount of the insulating resin layer 100 component. Because the electrode tab inputs and outputs power to the secondary battery Ba through the joining marks w, the increased resistance value at the joining marks w may reduce the charge / discharge efficiency of the secondary battery Ba.

[0093] On the other hand, if a secondary battery Ba is constructed by stacking single-metal layer electrodes 2 without using a clad electrode 1 and joining the single-layer ends 220 of the multiple single-metal layer electrodes 2, the safety of the secondary battery Ba may be reduced because it will not be possible to prevent the secondary battery Ba from catching fire or the like when it generates abnormal heat due to overcharging or the like (see Patent Document 1).

[0094] The secondary battery Ba of the present disclosure can achieve both safety and charge / discharge efficiency for the secondary battery Ba. The secondary battery Ba includes a clad electrode 1 and a single-metal layer electrode 2, and the clad end 120 of the clad electrode 1 is joined to the single-layer end 220 of the single-metal layer electrode 2. This reduces the amount of resin layer 100 components contained in the joining trace w compared to when the single-metal layer electrode 2 is not used, thereby reducing the resistance of the joining trace w. Furthermore, if the secondary battery Ba abnormally generates heat, the resin layer 100 of the clad electrode 1 melts, damaging the clad electrode 1. This interrupts current flow within the battery and can prevent the battery from catching fire, etc. As a result, the safety of the secondary battery Ba can be achieved together with charge / discharge efficiency.

[0095] In one embodiment, the clad electrode 1 includes active material layers 12a, 12b containing an active material, and the active material layers 12a, 12b are provided on at least one surface of the clad current collector 10. The single-metal layer electrode 2 includes active material layers 22a, 22b containing an active material, and the active material layers 22a, 22b are provided on at least one surface of the single-layer current collector 20. In one embodiment, the active material layers 12a, 12b of the clad electrode 1 have a weight per unit area that is smaller than the weight per unit area of ​​the active material layers 22a, 22b of the single-metal layer electrode 2. In one embodiment, the area of ​​the clad end 120 is larger than the area of ​​the single-layer end 220.

[0096] Because the clad electrode 1 includes the resin layer 100, when the active material weights of the active material layers 12a, 12b of the clad electrode 1 and the active material layers 22a, 22b of the single-metal layer electrode 2 are similar, and when the clad end 120 of the clad electrode 1 and the single-layer end 220 of the single-metal layer electrode 2 are similar in area, the resistance of the clad electrode 1 is greater than the resistance of the single-metal layer electrode 2. The difference in resistance between the clad electrode 1 and the single-metal layer electrode 2 leads to a decrease in the energy density of the secondary battery Ba. With these configurations, the resistances of the clad electrode 1 and the single-metal layer electrode 2 can be made uniform. This improves the energy density of the secondary battery Ba.

[0097] In one embodiment, the cladding end 120 and the single layer end 220 have a bonding mark w recessed from one side to the other in the stacking direction. Also, in one embodiment, the thickness of the metal layer 102 a provided on the one side of the resin layer 100 is greater than the thickness of the metal layer 102 b provided on the other side of the resin layer 100.

[0098] The bond mark w, which is recessed from one side to the other, is formed by applying a force from the one side to the other. In this case, the metal layer on the side where the force is applied (i.e., the metal layer 102a on the one side) is more likely to peel from the bond with the other metal layer than the metal layer on the side where the force is applied (i.e., the metal layer 102b on the other side). With this configuration, the metal layer on the side where the force is applied contains more metal, and is therefore strongly bonded to the single layer end 220, thereby suppressing peeling from the other metal layer.

[0099] In one embodiment, the bonding marks w are welding marks. With this configuration, the resistance value at the bonding marks w can be reduced, and the charge / discharge efficiency of the secondary battery Ba can be improved.

[0100] In one embodiment, the secondary battery Ba includes a plurality of clad electrodes 1 and a plurality of single-metal layer electrodes 2. This configuration can improve the energy density of the secondary battery Ba.

[0101] In one embodiment, one clad end portion 120 and one single layer end portion 220 are alternately stacked. This configuration makes it easier to achieve both safety and charge / discharge efficiency of the secondary battery Ba.

[0102] In one embodiment, the thickness of each of the pair of metal layers 102a, 102b is 0.3 μm or more. In one embodiment, the thickness of the single-layer current collector 20 is 4 μm or more. In one embodiment, the thickness of each of the pair of metal layers 102a, 102b is 1 / 30 or more of the thickness of the single-layer current collector 20. In one embodiment, the thickness of each of the pair of metal layers 102a, 102b is 1 / 2 or less of the thickness of the single-layer current collector 20. These parameters make it easier to achieve both safety and charge / discharge efficiency of the secondary battery Ba.

[0103] <4. Method of Using Secondary Battery> The secondary battery Ba is charged and discharged by further connecting the electrode tab for the positive electrode connected to the positive electrode end Pe to one end of an external circuit and further connecting the electrode tab for the negative electrode connected to the negative electrode end Ne to the other end of an external circuit. The external circuit may be, for example, a resistor, a power source, an apparatus, a device, another battery, or a potentiostat.

[0104] When a voltage is applied between the positive electrode tab and the negative electrode tab so that a current flows from the negative electrode tab to the positive electrode tab through an external circuit, the secondary battery Ba is charged. When the positive electrode tab and the negative electrode tab of the charged secondary battery Ba are connected via a desired external circuit, the secondary battery Ba is discharged.

[0105] 5. Other Configurations The secondary battery Ba may further include the following configurations.

[0106] [Electrolyte] In one embodiment, the secondary battery Ba may contain an electrolytic solution. The electrolytic solution is a liquid containing a solvent and an electrolyte and has ion conductivity. The electrolytic solution may also be referred to as a liquid electrolyte and acts as a conductive path for lithium ions. Therefore, when the secondary battery Ba contains an electrolytic solution, the internal resistance can be reduced, and the energy density, capacity, and cycle characteristics can be improved.

[0107] The electrolytic solution may be, for example, a solution filling the housing (pouch) of the secondary battery Ba. Alternatively, for example, the electrolytic solution may be impregnated into the separator 30, or may be held in a polymer to form a polymer electrolyte or a gel electrolyte.

[0108] The electrolyte contained in the electrolytic solution may be, for example, a lithium salt. Examples of the lithium salt include LiI, LiCl, LiBr, LiF, and LiBF. ４ , LiPF ６ , LiAsF ６ , LiSO ３ CF ３ , LiN(SO ２ F) ２ , LiN(SO ２ CF ３ ) ２ , LiN(SO ２ CF ３ CF３ ) ２ , LiB(O ２ C ２ H ４ ) ２ , LiB(C ２ O ４ ) ２ , LiB(O ２ C ２ H ４ ) F ２ , LiB(OCOCF ３ ) ４ , LiNO ３ , Li ２ SO ４ and LiFSI.

[0109] The solvent contained in the electrolytic solution may be, for example, a non-aqueous solvent containing fluorine atoms (hereinafter referred to as a "fluorinated solvent") or a non-aqueous solvent containing no fluorine atoms (hereinafter referred to as a "non-fluorinated solvent").

[0110] The fluorinated solvent may be, for example, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, and 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether.

[0111] The fluorine-free solvent may be, for example, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,2-dimethoxyethane, dimethoxyethane, dimethoxypropane, dimethoxybutane, diethylene glycol dimethyl ether, acetonitrile, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene carbonate, propylene carbonate, chloroethylene carbonate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, trimethyl phosphate, triethyl phosphate, and 12-crown-4.

[0112] The above fluorinated solvents and / or non-fluorinated solvents may be used alone or in any combination of two or more in any ratio. The contents of the fluorinated solvent and non-fluorinated solvent are not particularly limited, and the ratio of the fluorinated solvent to the total solvent may be 0 to 100% by volume, or the ratio of the non-fluorinated solvent to the total solvent may be 0 to 100% by volume.

[0113] [Separator 30] The separator 30 physically and / or electrically isolates the clad positive electrode 1p and / or the single-metal layer positive electrode 2p from the clad negative electrode 1n and / or the single-metal layer negative electrode 2n, while ensuring ionic conductivity of lithium ions. In one embodiment, the separator 30 may be at least one selected from the group consisting of an insulating porous material, a polymer electrolyte, a gel electrolyte, and an inorganic solid electrolyte. The separator 30 may be made of one material alone or a combination of two or more materials.

[0114] When the separator 30 includes an insulating porous member, the pores of the porous member are filled with an ion-conductive substance (such as an electrolytic solution, a polymer electrolyte, and / or a gel electrolyte). This allows the separator 30 to exhibit ion conductivity. The material constituting the insulating porous member is not particularly limited, and examples thereof include insulating polymer materials, specifically polyethylene (PE) and polypropylene (PP). That is, the separator 30 may be a porous polyethylene (PE) film, a porous polypropylene (PP) film, or a laminate structure thereof.

[0115] In one embodiment, one or both surfaces of the separator 30 may be coated with a separator coating layer. This may improve the cycle characteristics of the secondary battery Ba. In one embodiment, the separator coating layer may be a continuous film with a uniform thickness over 50% or more of the surface area of ​​the separator 30. In one embodiment, the separator coating layer may include a binder such as polyvinylidene fluoride (PVDF), a mixture of styrene butadiene rubber and carboxymethyl cellulose (SBR-CMC), and polyacrylic acid (PAA). In one embodiment, the separator coating layer may be formed by adding inorganic particles such as silica, alumina, titania, zirconia, or magnesium hydroxide to the binder.

[0116] In one embodiment, the average thickness of separator 30 (including the coating layer if separator 30 includes the coating layer) may be 3.0 μm or more and 40 μm or less. This can reduce the volume occupied by separator 30 while isolating clad positive electrode 1p and / or single-metal layer positive electrode 2p from clad negative electrode 1n and / or single-metal layer negative electrode 2n. In one embodiment, the average thickness of separator 30 may be 5.0 μm or more and 30 μm or less, 7.0 μm or more and 10 μm or less, or 10 μm or more and 20 μm or less.

[0117] 6. Modified Examples

[0118] [Modifications of Clad Negative Electrode In / Single-Metal Layer Negative Electrode 2] In the above embodiment, the clad negative electrode In includes the negative electrode active material layers 12a and 12nb, and the single-metal layer electrode 2 includes the negative electrode active material layers 22na and 22nb. However, this is not limited thereto. The clad negative electrode In and / or the single-metal layer negative electrode 2n may be substantially free of negative electrode active material.

[0119] In one embodiment, the clad negative electrode 1n and / or the single metal layer negative electrode 2n do not have a negative electrode active material before the initial charge of the battery (the state from the assembly of the battery to the first charge). After the initial charge, the secondary battery Ba may be charged and discharged by depositing lithium metal on the negative electrode and electrolytically dissolving the deposited lithium metal. In this case, the volume and mass occupied by the negative electrode active material are reduced, the volume and mass of the entire battery are reduced, and the energy density is, in principle, increased. Note that "lithium metal deposited on the negative electrode" refers not only to lithium metal being deposited on the surface of the negative electrode, but also to lithium metal being deposited on the surface of a solid electrolyte interface (SEI) layer or on or within a buffer functional layer, as described below.

[0120] In one embodiment, the thickness of the layer of negative electrode active material deposited on the clad negative electrode 1n and / or the single metal layer negative electrode 2n at the end of discharge (e.g., when the open circuit voltage of the battery is 2.5 V or more and 3.6 V or less) is 25 μm or less. In one embodiment, the thickness of the layer of negative electrode active material at the end of discharge may be 20 μm or less, 15 μm or less, 10 μm or less, or 5 μm or less, or may even be 0 μm. Since the clad negative electrode 1n and / or the single metal layer negative electrode 2n are substantially free of negative electrode active material, the energy density per volume can be improved in addition to the energy density per weight. In this case, the secondary battery Ba can also be referred to as an "anode-free lithium battery," a "zero anode lithium battery," or an "anodeless lithium battery."

[0121] In one embodiment, the mass of lithium metal deposited on the negative electrode when the voltage is 4.2 V is M ４．２ The same mass at a voltage of 3.0 V is M ３．０ In this case, M ３．０ / M ４．２ may be 40% or less, or 35% or less. ３．０ / M ４．２ may be 1.0% or more, 2.0% or more, 3.0% or more, or 4.0% or more.

[0122] [Variations on the Stacking Method of Clad Electrodes 1 and Single-Metal Layer Electrodes 2] - Difference in the Number of Clad Electrodes 1 and Single-Metal Layer Electrodes 2 - In the above embodiment, an example was described in which the secondary battery Ba is constructed by stacking approximately the same number of single-metal layer electrodes 2 as the clad electrodes 1, but this is not limited to this. Specifically, the secondary battery Ba may be constructed by stacking clad positive electrodes 1p in a number equal to or greater than ¼ and equal to or less than ¾ of the number of single-metal layer positive electrodes 2p. Furthermore, the secondary battery Ba may be constructed by stacking clad negative electrodes 1n in a number equal to or greater than ¼ and equal to or less than ¾ of the number of single-metal layer negative electrodes 2n. This configuration allows the secondary battery Ba to meet various performance requirements while achieving both safety and charge / discharge efficiency.

[0123] In the above embodiment, an example in which the clad end portions 120 and the single layer end portions 220 are alternately stacked has been described, but this is not limiting. The secondary battery Ba may be configured by stacking a plurality of single layer end portions 220 between one clad end portion 120 and another clad end portion 120. Note that the clad end portions 120 do not need to be stacked between the plurality of single layer end portions 220. In other words, the plurality of single layer end portions 220 may be stacked continuously. The secondary battery Ba may be configured, for example, by stacking the following (1) or (2).

[0124] (1) Two pairs of a single-metal layer positive electrode 2p and a single-metal layer negative electrode 2n and one pair of a clad positive electrode 1p and a clad negative electrode 1n are periodically stacked. That is, the single-metal layer positive electrode 2p, the single-metal layer negative electrode 2n, the single-metal layer positive electrode 2p, the single-metal layer negative electrode 2n, the clad positive electrode 1p, and the clad negative electrode 1n are stacked in this order and periodically.

[0125] In this case, if the single-layer positive electrode end portion 220p of the single-metal layer positive electrode 2p and the clad positive electrode end portion 120p of the clad positive electrode 1p extend to one side, and the single-layer negative electrode end portion 220n of the single-metal layer negative electrode 2n and the clad negative electrode end portion 120n of the clad negative electrode 1n extend to the other side, then on that side, two single-layer positive electrode end portions 220p are stacked between the clad positive electrode end portion 120p and another clad positive electrode end portion 120p. Also, on the other side, two single-layer negative electrode end portions 220n are stacked between the clad negative electrode end portion 120n and another clad negative electrode end portion 120n.

[0126] (2) Three pairs of a single-metal layer positive electrode 2p and a single-metal layer negative electrode 2n and one pair of a clad positive electrode 1p and a clad negative electrode 1n are periodically stacked. That is, the single-metal layer positive electrode 2p, the single-metal layer negative electrode 2n, the single-metal layer positive electrode 2p, the single-metal layer negative electrode 2n, the single-metal layer positive electrode 2p, the single-metal layer negative electrode 2n, the clad positive electrode 1p, and the clad negative electrode 1n are stacked in this order and periodically.

[0127] In this case, if the single-layer positive electrode end portion 220p of the single-metal layer positive electrode 2p and the clad positive electrode end portion 120p of the clad positive electrode 1p extend to one side, and the single-layer negative electrode end portion 220n of the single-metal layer negative electrode 2n and the clad negative electrode end portion 120n of the clad negative electrode 1n extend to the other side, three single-layer positive electrode end portions 220p are stacked between the clad positive electrode end portion 120p and another clad positive electrode end portion 120p on that side, and three single-layer negative electrode end portions 220n are stacked between the clad negative electrode end portion 120n and another clad negative electrode end portion 120n on the other side.

[0128] Similarly, the secondary battery Ba may be configured by stacking a plurality of clad end portions 120 between one single layer end portion 220 and another single layer end portion 220. Note that the single layer end portions 220 do not have to be stacked between the plurality of clad end portions 120. In other words, the plurality of clad end portions 120 may be stacked continuously.

[0129] ~Stacking of Clad Electrodes 1 and Single-Metal Layer Electrodes 2 in Pairs~ In the above embodiment, an example has been described in which a clad positive electrode 1p and a clad negative electrode 1n are stacked in pairs, and a single-metal layer positive electrode 2p and a single-metal layer negative electrode 2n are stacked in pairs, respectively. However, this is not limiting. The secondary battery Ba may be configured by stacking a clad positive electrode 1p and a single-metal layer negative electrode 2n in pairs, and a clad negative electrode 1n and a single-metal layer positive electrode 2p in pairs. For example, instead of periodically stacking three pairs of a single-metal layer positive electrode 2p and a single-metal layer negative electrode 2n and one pair of a clad positive electrode 1p and a clad negative electrode 1n, three pairs of a clad positive electrode 1p and a single-metal layer negative electrode 2n and one pair of a single-metal layer positive electrode 2p and a clad negative electrode 1n may be stacked.

[0130] Multiple Stacked Structures In the above embodiment, an example in which the secondary battery Ba has a common stacked structure throughout has been described. In this disclosure, the term "stacked structure" refers to the stacking configuration of the clad electrodes 1 and single-metal layer electrodes 2, and includes, for example, the number of clad electrodes 1 and single-metal layer electrodes 2, the stacking order, and the repetition period. For example, FIG. 3 in the above embodiment illustrates an example in which the secondary battery Ba has a stacked structure in which a single-metal layer positive electrode 2p, a single-metal layer negative electrode 2n, a clad positive electrode 1p, and a clad negative electrode 1n are stacked in order and periodically. In contrast, the secondary battery Ba may have a portion having a first stacked structure and a portion having a second stacked structure. The secondary battery Ba may have, for example, either of the following stacked structures (1) and (2). (1) A portion having a first laminated structure in which one pair of a single metal layer positive electrode 2p and a single metal layer negative electrode 2n and one pair of a clad positive electrode 1p and a clad negative electrode 1n are periodically laminated, and (2) A portion having a second laminated structure in which four pairs of a single metal layer positive electrode 2p and a single metal layer negative electrode 2n and one pair of a clad positive electrode 1p and a clad negative electrode 1n are periodically laminated.

[0131] In this case, the portion having the second stacking configuration may be provided between the portion having the first stacking configuration and another portion having the first stacking configuration. The secondary battery Ba may have, for example, the following portions (1) to (3) in the stacking direction: (1) a portion having a first stacking configuration in which one pair of a single-metal layer positive electrode 2p and a single-metal layer negative electrode 2n and one pair of a clad positive electrode 1p and a clad negative electrode 1n are periodically stacked; (2) a portion having a second stacking configuration in which four pairs of a single-metal layer positive electrode 2p and a single-metal layer negative electrode 2n and one pair of a clad positive electrode 1p and a clad negative electrode 1n are periodically stacked; or (3) a portion having a first stacking configuration in which one pair of a single-metal layer positive electrode 2p and a single-metal layer negative electrode 2n and one pair of a clad positive electrode 1p and a clad negative electrode 1n are periodically stacked.

[0132] 7. Embodiments of the Present Disclosure The embodiments of the present disclosure further include the following aspects: Note that the correspondence between the terms in the above embodiments and those in the above embodiments is indicated in parentheses.

[0133] [Supplementary Note 1] A secondary battery Ba includes a first electrode sheet (clad electrode 1) and a second electrode sheet (single metal layer electrode 2) having the same polarity as the first electrode sheet (clad electrode 1), wherein the first electrode sheet (clad electrode 1) is a first current collector (clad current collector 10) having a resin layer 100 and a pair of metal layers 102a, 102b provided on both sides of the resin layer 100, and a first end (clad electrode 10) at which the pair of metal layers 102a, 102b are exposed. a second electrode sheet (single metal layer electrode 2) including a second current collector (single layer current collector 20) that contains a metal and does not include a resin layer 100, the second current collector (single layer current collector 20) having a second end (single layer end 220) where the metal is exposed, and the first end (clad end 120) and the second end (single layer end 220) are stacked and joined together.

[0134] [Supplementary Note 2] The secondary battery Ba according to Supplementary Note 1, wherein the first electrode sheet (clad electrode 1) includes a first active material layer (active material layers 12a, 12b) containing an active material, and the first active material layer (active material layers 12a, 12b) is provided on at least one surface of the first current collector (clad current collector 10); and the second electrode sheet (single-metal layer electrode 2) includes a second active material layer (active material layers 22a, 22b) containing an active material, and the second active material layer (active material layers 22a, 22b) is provided on at least one surface of the second current collector (single-layer current collector 20).

[0135] [Appendix 3] The secondary battery Ba according to Appendix 2, wherein the basis weight of the first active material layer (active material layers 12a, 12b) of the first electrode sheet (clad electrode 1) is smaller than the basis weight of the second active material layer (active material layers 22a, 22b) of the second electrode sheet (single metal layer electrode 2).

[0136] [Supplementary Note 4] The secondary battery Ba according to any one of Supplementary Note 1 to Supplementary Note 3, wherein the area of ​​the first end (clad end 120) is larger than the area of ​​the second end (single layer end 220).

[0137] [Appendix 5] A secondary battery Ba described in any one of Appendices 1 to 4, wherein the first end (clad end 120) and the second end (single layer end 220) have bonding marks (positive electrode bonding mark Pw, negative electrode bonding mark Nw) recessed from one side to the other in the stacking direction.

[0138] [Supplementary Note 6] The secondary battery Ba according to Supplementary Note 5, wherein the thickness of the metal layer 102a provided on one side of the resin layer 100 is greater than the thickness of the metal layer 102b provided on the other side of the resin layer 100.

[0139] [Appendix 7] The secondary battery Ba according to appendix 6, wherein the joining marks (positive electrode joining marks Pw, negative electrode joining marks Nw) are welding marks.

[0140] [Supplementary Note 8] The secondary battery Ba according to any one of Supplementary Note 1 to Supplementary Note 7, including a plurality of first electrode sheets (clad electrodes 1) and a plurality of second electrode sheets (single metal layer electrodes 2).

[0141] [Supplementary Note 9] The secondary battery Ba according to Supplementary Note 8, wherein one first end portion (clad end portion 120) and one second end portion (single layer end portion 220) are alternately stacked with each other.

[0142] [Supplementary Note 10] The secondary battery Ba according to Supplementary Note 8, wherein a plurality of second ends (single layer ends 220) are stacked between a plurality of first ends (clad ends 120).

[0143] [Appendix 11] The secondary battery Ba according to Appendix 8, wherein the number of second electrode sheets (single metal layer electrodes 2) is equal to or greater than ¼ and equal to or less than ¾ of the number of first electrode sheets (clad electrodes 1).

[0144] [Supplementary Note 12] The secondary battery Ba according to any one of Supplementary Note 1 to Supplementary Note 11, wherein the thickness of each of the pair of metal layers 102a, 102b is 0.3 μm or more.

[0145] [Appendix 13] The secondary battery Ba according to any one of Appendices 1 to 12, wherein the second current collector (single-layer current collector 20) has a thickness of 4 μm or more.

[0146] [Supplementary Note 14] The secondary battery Ba according to any one of Supplementary Note 1 to Supplementary Note 14, wherein the thickness of each of the pair of metal layers 102a, 102b is 1 / 30 or more of the thickness of the second current collector (single-layer current collector 20).

[0147] [Supplementary Note 15] The secondary battery Ba according to any one of Supplementary Note 1 to Supplementary Note 14, wherein the thickness of each of the pair of metal layers 102a, 102b is equal to or less than half the thickness of the second current collector (single-layer current collector 20).

[0148] [Supplementary Note 16] The secondary battery Ba according to any one of Supplementary Note 1 to Supplementary Note 15, wherein the first electrode sheet (clad electrode 1) and the second electrode sheet (single metal layer electrode 2) are positive electrode sheets.

[0149] [Appendix 17] The secondary battery Ba according to appendix 16, wherein the pair of metal layers 102a, 102b and the second current collector (single-layer current collector 20) contain aluminum.

[0150] [Supplementary Note 18] The secondary battery Ba according to any one of Supplementary Note 1 to Supplementary Note 17, wherein the first electrode sheet (clad electrode 1) and the second electrode sheet (single metal layer electrode 2) are negative electrode sheets.

[0151] [Appendix 19] The secondary battery Ba according to appendix 18, wherein the pair of metal layers 102a, 102b and the second current collector (single-layer current collector 20) contain copper.

[0152] [Appendix 20] The secondary battery Ba according to appendix 18, wherein the first electrode sheet (clad electrode 1) and the second electrode sheet (single metal layer electrode 2) are substantially free of a negative electrode active material.

[0153] Ba...secondary battery, 1...clad electrode, 1n...clad negative electrode, 1p...clad positive electrode, 2...single metal layer electrode, 2...single metal layer positive electrode, 2n...single metal layer negative electrode, 2p...single metal layer positive electrode, 3...single metal layer negative electrode, 4...clad positive electrode, 10...clad current collector, 10n...clad negative electrode current collector, 10p...clad positive electrode current collector, 12a, 12b...active material layer, 12na, 12nb...negative electrode active material layer, 12pa, 12pb...positive electrode active material layer, 16a...first active material layer, 16b...second active material layer, 20...single layer current collector, 20n, 20p...single layer negative electrode current collector, 22a , 22b...active material layer, 22na, 22nb...negative electrode active material layer, 22pa, 22pb...positive electrode active material layer, 30...separator, 100...resin layer, 102a, 102b...metal layer, 102na, 102nb...negative electrode metal layer, 102pa, 102pb...positive electrode metal layer, 120...clad end, 120n...clad negative electrode end, 120p...clad positive electrode end, 220...single layer end, 220n...single layer negative electrode end, 220p...single layer positive electrode end, Am...active material stacking region, Ne...negative electrode end, Nw...negative electrode bonding trace, Pe...positive electrode end, Pw...positive electrode bonding trace, w...bonding trace

Claims

1. A secondary battery including a first electrode sheet and a second electrode sheet having the same polarity as the first electrode sheet, wherein the first electrode sheet is a first current collector having a resin layer and a pair of metal layers provided on each of both surfaces of the resin layer, the first current collector having a first end portion where the pair of metal layers are exposed, and the second electrode sheet is a second current collector composed of a metal and not including a resin layer, the second current collector having a second end portion where the metal is exposed, and the first end portion and the second end portion are laminated and joined together.

2. The first electrode sheet includes a first active material layer containing an active material, and the first active material layer is provided on at least one surface of the first current collector. The second electrode sheet includes a second active material layer containing the active material, and the second active material layer is provided on at least one surface of the second current collector. The secondary battery according to claim 1.

3. The basis weight of the first active material layer of the first electrode sheet is smaller than the basis weight of the second active material layer of the second electrode sheet. The secondary battery according to claim 2.

4. The area of the first end portion is larger than the area of the second end portion. The secondary battery according to claim 1.

5. The first end portion and the second end portion are provided with a joining mark that is recessed from one side to the other side in the lamination direction. The secondary battery according to claim 1.

6. The thickness of the metal layer provided on one side of the resin layer is larger than the thickness of the metal layer provided on the other side of the resin layer. The secondary battery according to claim 5.

7. The joining mark is a welding mark. The secondary battery according to claim 6.

8. The secondary battery according to claim 1, including a plurality of the first electrode sheets and a plurality of the second electrode sheets.

9. One of the first end portions and one of the second end portions are alternately laminated with each other. The secondary battery according to claim 8.

10. A plurality of the second end portions are laminated between a plurality of the first end portions and a plurality of the first end portions. The secondary battery according to claim 8.

11. The number of the second electrode sheets is 1 / 4 or more and 3 / 4 or less of the number of the first electrode sheets. The secondary battery according to claim 8.

12. The thickness of each of the pair of metal layers is 0.3 μm or more. The secondary battery according to claim 1.

13. The thickness of the second current collector is 4 μm or more. The secondary battery according to claim 1.

14. The thickness of each of the pair of metal layers is 1 / 30 or more of the thickness of the second current collector. The secondary battery according to claim 1.

15. The thickness of each of the pair of metal layers is 1 / 2 or less of the thickness of the second current collector. The secondary battery according to claim 1.

16. The first electrode sheet and the second electrode sheet are positive electrode sheets. The secondary battery according to claim 1.

17. The pair of metal layers and the second current collector are composed of aluminum. The secondary battery according to claim 16.

18. The first electrode sheet and the second electrode sheet are negative electrode sheets. The secondary battery according to claim 1.

19. The pair of metal layers and the second current collector are composed of copper. The secondary battery according to claim 18.

20. The first electrode sheet and the second electrode sheet substantially do not have a negative electrode active material. The secondary battery according to claim 18.

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