JP2023150728A - Electrode for laminated power storage element, and laminated power storage element - Google Patents

Abstract

To provide an electrode for a laminated power storage element that is excellent in durability of a tab part.SOLUTION: An electrode 10 comprises: a rectangular electrode base material 12 consisting of a rolled metal foil; and a tab part 11 integrally formed with the electrode base material 12 and protruding from a short side of the electrode base material 12. A protrusion direction of the tab part 11 is along a direction of rolling of the rolled metal foil.SELECTED DRAWING: Figure 1

Description

The present invention relates to an electrode for a stacked power storage element and a stacked power storage element.

Non-aqueous electrolyte secondary batteries, typified by lithium ion secondary batteries, are widely used in electronic devices such as personal computers, communication terminals, automobiles, etc. due to their high energy density. In addition, as power storage devices other than nonaqueous electrolyte secondary batteries, capacitors such as lithium ion capacitors and electric double layer capacitors, power storage devices using electrolytes other than nonaqueous electrolytes, and the like are also widely used.

Typically, a positive electrode plate of a power storage element has a main body portion in which active material composite layers are formed on both sides of a rectangular core made of, for example, aluminum foil. A positive electrode tab, which is an extending core, is formed on the positive electrode plate, and the positive electrode tab is electrically connected to a positive electrode terminal via a positive electrode current collector (see Patent Document 1).

Japanese Patent Application Publication No. 2019-179654

Since the tabs of the electrodes of such power storage elements serve as current paths, durability is required.

An object of the present invention is to provide an electrode with a tab having excellent durability, and a laminated power storage element including such an electrode.

An electrode for a laminated power storage element according to one aspect of the present invention includes a rectangular electrode base material made of rolled metal foil, and a tab that is integrally formed with the electrode base material and protrudes from a short side of the electrode base material. and a protruding direction of the tab portion is along the rolling direction of the rolled metal foil.

A stacked power storage device according to another aspect of the present invention includes an electrode for a stacked power storage device according to another aspect of the present invention.

According to one aspect of the present invention, it is possible to provide an electrode for a stacked power storage element whose tab portion has excellent durability, and a stacked power storage element including such an electrode.

FIG. 1 is a schematic diagram showing one embodiment of an electrode for a stacked power storage element. FIG. 2 is a schematic diagram showing an embodiment of an electrode base material and a tab portion. FIG. 3 is a schematic exploded perspective view showing one embodiment of a stacked power storage element. FIG. 4 is a schematic diagram showing an embodiment of a power storage device configured by collecting a plurality of power storage elements.

First, an overview of the electrode for a stacked power storage element and the stacked power storage element disclosed in this specification will be described.

An electrode for a laminated power storage element according to one aspect of the present invention includes a rectangular electrode base material made of rolled metal foil, and a tab that is integrally formed with the electrode base material and protrudes from a short side of the electrode base material. and a protruding direction of the tab portion is along the rolling direction of the rolled metal foil.

The electrode for a stacked power storage element according to one aspect of the present invention has excellent durability of the tab portion. Possible reasons for this are as follows. The tab portion of the electrode for the laminated power storage element is formed integrally with the electrode base material, protrudes from the short side of the electrode base material, and the protruding direction of the tab portion is along the rolling direction of the rolled metal foil. ing. Since rolled metal foil has high strength in the rolling direction, the tab portion has excellent strength in the protruding direction where high strength is required. Therefore, the tab portion of the electrode for the laminated power storage element has excellent durability. Furthermore, since the tab portion protrudes from the short side of the electrode base material, the current collection space formed by the positive electrode tab portion and the negative electrode tab portion within the battery container can be reduced, and thus the energy density can be increased. Furthermore, since the rolling direction of the rolled metal foil is along the protruding direction of the tab portion, that is, the long side direction of the electrode base material, the amount of deflection of the electrode base material is reduced, making it easier to handle during lamination in the manufacturing process, etc. becomes.

The above-mentioned "rolling direction of rolled metal foil" means the direction in which the metal foil extends when the metal foil is passed between a pair of rolls and rolled in the rolling process of the rolled metal foil. The above-mentioned rolling direction refers to the direction in which the tab portion is cut along a longitudinal section and a transverse section, and the crystal grain size is larger in an image of the cut section observed with a metallurgical microscope.

A stacked power storage device according to another aspect of the present invention is a stacked power storage device including an electrode for a stacked power storage device according to one aspect of the present invention. The laminated power storage element has excellent durability in the tab portion of the electrode.

A structure of an electrode for a stacked power storage element, a structure of a stacked power storage element, a structure of a power storage device, a method for manufacturing a stacked power storage element, and other embodiments according to an embodiment of the present invention will be described in detail. Note that the name of each component (each component) used in each embodiment may be different from the name of each component (each component) used in the background art.

<Electrode>
The electrode for a stacked power storage element according to an embodiment of the present invention is used as a positive electrode or a negative electrode in a stacked power storage element including a stacked electrode body in which a flat positive electrode and a flat negative electrode are stacked. The electrode includes an electrode base material and the tab portion. Further, the electrode has an active material layer disposed directly on the electrode base material or via an intermediate layer. The electrode may be a positive electrode, a negative electrode, or both a positive electrode and a negative electrode.

FIG. 1 is a schematic diagram showing one embodiment of an electrode for a stacked power storage element. FIG. 2 is a schematic diagram showing an embodiment of an electrode base material and a tab portion. As shown in FIG. 1, the electrode 10 has a rectangular (rectangular) electrode base material 12 made of rolled metal foil and a tab portion 11. Further, the electrode 10 has an active material layer 13 laminated on a part of the surface of the electrode base material 12. The active material layer 13 is formed on one or both sides of the electrode base material 12. In the tab portion 11, the active material layer 13 is not formed, and the rolled metal foil is exposed. In addition, in the electrode 10, the active material layer 13 is formed on the entire surface of the electrode base material 12, and the rolled metal foil may be exposed only at the tab portion 11.

The electrode base material 12 and the tab portion 11 are formed from rolled metal foil. As shown in FIG. 2, the tab portion 11 has a rectangular shape, for example. The tab portion 11 is formed integrally with the electrode base material 12 and protrudes from one side of the short side 18 of the electrode base material 12. The rolling direction R of the rolled metal foil constituting the electrode base material 12 and the tab portion 11 is along the protruding direction of the tab portion 11 (the long side direction of the electrode base material 12).

The average thickness of the electrode base material 12 and the tab portion 11 is preferably 2 μm or more and 50 μm or less, more preferably 3 μm or more and 40 μm or less, even more preferably 4 μm or more and 30 μm or less, and particularly preferably 5 μm or more and 25 μm or less. By setting the average thickness of the electrode base material 12 and the tab portion 11 within the above range, it is possible to increase the energy density per volume of the laminated power storage element while increasing the strength of the electrode base material and the tab portion.

The lower limit of the average length of the tab portion 11 in the protruding direction (the long side direction of the electrode base material 12) is preferably 5 mm, and more preferably 8 mm. On the other hand, the upper limit of the average length of the tab portion 11 is preferably 35 mm, more preferably 30 mm. Favorable current collection can be achieved because the average length is equal to or greater than the lower limit. On the other hand, since the average length is equal to or less than the upper limit, the strength of the tab portion 11 can be kept within a good range.

The lower limit of the average width in the direction perpendicular to the protruding direction of the tab portion 11 (the short side direction of the electrode base material 12) is preferably 10 mm, and more preferably 15 mm. On the other hand, the upper limit of the average width of the tab portion 11 is preferably 60 mm, more preferably 50 mm. When the average width is equal to or greater than the lower limit, the strength of the tab portion 11 can be kept within a good range. On the other hand, contact with other components can be suppressed because the average width is equal to or less than the upper limit.

The lower limit of the ratio of the average length in the protruding direction to the average width in the direction orthogonal to the protruding direction of the tab portion 11 is preferably 0.08, more preferably 0.16. On the other hand, the upper limit of the ratio of the average length to the average width of the tab portion 11 is preferably 3.5, more preferably 2.0. When the ratio of the average length to the average width of the tab portion 11 is at least the above lower limit, current can be collected favorably. On the other hand, when the ratio of the average length to the average width of the tab portion 11 is equal to or less than the upper limit, the strength of the tab portion 11 can be kept in a good range.

The ratio of the length of the long side of the electrode base material 12 to the length of the short side 18 of the electrode base material 12 is preferably greater than 1.0 and less than or equal to 3.6, more preferably greater than or equal to 1.5 and less than or equal to 3.0.

The electrode base material 12 has electrical conductivity. Whether or not it has "conductivity" is determined using a volume resistivity of 10 ⁻² Ω·cm as a threshold value, which is measured in accordance with JIS-H-0505 (1975).

As the material of the rolled metal foil used as the electrode base material (positive electrode base material) when the electrode 10 is a positive electrode, metals such as aluminum, titanium, tantalum, stainless steel, or alloys thereof are used. Among these, aluminum or aluminum alloy is preferred from the viewpoint of potential resistance, high conductivity, and cost. Therefore, as the positive electrode base material, rolled aluminum foil or rolled aluminum alloy foil is preferable. Examples of aluminum or aluminum alloy include A1085, A3003, A1N30, etc. specified in JIS-H-4000 (2014) or JIS-H-4160 (2006).

When the electrode 10 is a negative electrode, the rolled metal foil used as the electrode base material (negative electrode base material) may be made of metals such as copper, nickel, stainless steel, nickel-plated steel, aluminum, or alloys thereof. . Among these, copper or copper alloy is preferred. Therefore, rolled copper foil or rolled copper alloy foil is preferable as the negative electrode base material.

The intermediate layer is a layer disposed between the electrode base material and the active material layer. The intermediate layer reduces contact resistance between the electrode base material and the active material layer by containing a conductive agent such as carbon particles. The structure of the intermediate layer is not particularly limited, and includes, for example, a binder and a conductive agent.

Active material layer 13 contains an active material. The active material layer contains optional components such as a conductive agent, a binder, a thickener, and a filler, as necessary.

When the electrode 10 is a positive electrode, the positive electrode active material can be appropriately selected from known positive electrode active materials. As a positive electrode active material for a lithium ion secondary battery, a material that can insert and release lithium ions is usually used. Examples of the positive electrode active material include a lithium transition metal composite oxide having an α-NaFeO ₂ type crystal structure, a lithium transition metal composite oxide having a spinel type crystal structure, a polyanion compound, a chalcogen compound, and sulfur. Examples of lithium transition metal composite oxides having α-NaFeO type ₂ crystal structure include Li[Li _x Ni _(1-x) ]O ₂ (0≦x<0.5), Li[Li _x Ni _γ Co _{( 1-x-γ)} ]O ₂ (0≦x<0.5, 0<γ<1), Li[Li _x Co _(1-x) ]O ₂ (0≦x<0.5), Li[ Li _x Ni _γ Mn _(1-x-γ) ]O ₂ (0≦x<0.5, 0<γ<1), Li[Li _x Ni _γ Mn _β Co _(1-x-γ-β) ] O ₂ (0≦x<0.5, 0<γ, 0<β, 0.5<γ+β<1), Li[Li _x Ni _γ Co _β Al _(1-x-γ-β) ]O ₂ ( Examples include 0≦x<0.5, 0<γ, 0<β, 0.5<γ+β<1). Examples of lithium transition metal composite oxides having a spinel crystal structure include Li _x Mn ₂ O ₄ and Li _x Ni _γ Mn _(2-γ) O ₄ . Examples of the polyanion compound include LiFePO ₄ , LiMnPO ₄ , LiNiPO ₄ , LiCoPO ₄ , Li ₃ V ₂ (PO ₄ ) ₃ , Li ₂ MnSiO ₄ , Li ₂ CoPO ₄ F, and the like. Examples of chalcogen compounds include titanium disulfide, molybdenum disulfide, molybdenum dioxide, and the like. Atoms or polyanions in these materials may be partially substituted with atoms or anion species of other elements. The surfaces of these materials may be coated with other materials. In the positive electrode active material layer, one type of these materials may be used alone, or two or more types may be used in combination.

The positive electrode active material is usually particles (powder). The average particle size of the positive electrode active material is preferably, for example, 0.1 μm or more and 20 μm or less. By setting the average particle size of the positive electrode active material to be equal to or larger than the above lower limit, manufacturing or handling of the positive electrode active material becomes easier. By setting the average particle size of the positive electrode active material to be equal to or less than the above upper limit, the electronic conductivity of the positive electrode active material layer is improved. Note that when a composite of a positive electrode active material and another material is used, the average particle size of the composite is defined as the average particle size of the positive electrode active material. "Average particle size" is based on the particle size distribution measured by laser diffraction/scattering method on a diluted solution of particles diluted with a solvent, in accordance with JIS-Z-8825 (2013). -2 (2001), which means the value at which the volume-based cumulative distribution calculated in accordance with 2001 is 50%.

A pulverizer, classifier, etc. are used to obtain powder with a predetermined particle size. Examples of the pulverization method include methods using a mortar, a ball mill, a sand mill, a vibrating ball mill, a planetary ball mill, a jet mill, a counter jet mill, a swirling jet mill, a sieve, and the like. At the time of pulverization, wet pulverization in which water or a non-aqueous solvent such as hexane is present can also be used. As for the classification method, a sieve, a wind classifier, etc. may be used, both dry and wet, as necessary.

The content of the positive electrode active material in the positive electrode active material layer is preferably 50% by mass or more and 99% by mass or less, more preferably 70% by mass or more and 98% by mass or less, and even more preferably 80% by mass or more and 95% by mass or less. By setting the content of the positive electrode active material within the above range, it is possible to achieve both high energy density and manufacturability of the positive electrode active material layer.

When the electrode 10 is a negative electrode, the negative electrode active material can be appropriately selected from known negative electrode active materials. As a negative electrode active material for a lithium ion secondary battery, a material that can insert and release lithium ions is usually used. Examples of negative electrode active materials include metal Li; metals or semimetals such as Si and Sn; metal oxides or semimetal oxides such as Si oxide, Ti oxide, and Sn oxide; Li ₄ Ti ₅ O ₁₂ , Examples include titanium-containing oxides such as LiTiO _{2 and} TiNb ₂ O ₇ ; polyphosphoric acid compounds; silicon carbide; carbon materials such as graphite and non-graphitizable carbon (easily graphitizable carbon or non-graphitizable carbon); It will be done. Among these materials, graphite and non-graphitic carbon are preferred. In the negative electrode active material layer, one type of these materials may be used alone, or two or more types may be used in combination.

"Graphite" refers to a carbon material whose average lattice spacing (d ₀₀₂ ) of the (002) plane is 0.33 nm or more and less than 0.34 nm, as determined by X-ray diffraction, before charging and discharging or in a discharged state. . Examples of graphite include natural graphite and artificial graphite. Artificial graphite is preferred from the viewpoint of being able to obtain a material with stable physical properties.

"Non-graphitic carbon" is a carbon material whose average lattice spacing (d ₀₀₂ ) of the (002) plane is 0.34 nm or more and 0.42 nm or less, as determined by X-ray diffraction before charging and discharging or in a discharged state. means. Examples of non-graphitic carbon include non-graphitizable carbon and easily graphitizable carbon. Examples of the non-graphitic carbon include resin-derived materials, petroleum pitch or petroleum pitch-derived materials, petroleum coke or petroleum coke-derived materials, plant-derived materials, alcohol-derived materials, and the like.

Here, the "discharged state" of carbon materials such as graphite refers to the state in which the carbon material, which is the negative electrode active material, is discharged in such a way that ions such as lithium, which can be inserted and released during charging and discharging, are sufficiently released. means state. For example, in a half cell in which a negative electrode containing a carbon material as a negative electrode active material is used as a working electrode and metal lithium (Li) is used as a counter electrode, the open circuit voltage is 0.7 V or more.

"Non-graphitizable carbon" refers to a carbon material in which the above d ₀₀₂ is 0.36 nm or more and 0.42 nm or less.

"Graphitizable carbon" refers to a carbon material in which the above d ₀₀₂ is 0.34 nm or more and less than 0.36 nm.

The negative electrode active material is usually particles (powder). The average particle size of the negative electrode active material can be, for example, 1 nm or more and 100 μm or less. When the negative electrode active material is a carbon material, a titanium-containing oxide, or a polyphosphoric acid compound, the average particle size thereof may be 1 μm or more and 100 μm or less. When the negative electrode active material is Si, Sn, Si oxide, Sn oxide, or the like, the average particle size thereof may be 1 nm or more and 1 μm or less. By setting the average particle size of the negative electrode active material to be equal to or larger than the above lower limit, manufacturing or handling of the negative electrode active material becomes easier. By setting the average particle size of the negative electrode active material to be less than or equal to the above upper limit, the electronic conductivity of the active material layer is improved. A pulverizer, classifier, etc. are used to obtain powder with a predetermined particle size. The pulverization method and classification method can be selected from, for example, the methods exemplified for the positive electrode. When the negative electrode active material is a metal such as metal Li, the negative electrode active material may be in the form of a foil.

The content of the negative electrode active material in the negative electrode active material layer is preferably 60% by mass or more and 99% by mass or less, more preferably 90% by mass or more and 98% by mass or less. By setting the content of the negative electrode active material within the above range, it is possible to achieve both high energy density and manufacturability of the negative electrode active material layer.

The conductive agent is not particularly limited as long as it is a conductive material. Examples of such conductive agents include carbonaceous materials, metals, conductive ceramics, and the like. Examples of the carbonaceous material include graphite, non-graphitic carbon, graphene-based carbon, and the like. Examples of non-graphitic carbon include carbon nanofibers, pitch-based carbon fibers, carbon black, and the like. Examples of carbon black include furnace black, acetylene black, Ketjen black, and the like. Examples of graphene-based carbon include graphene, carbon nanotubes (CNT), and fullerene. Examples of the shape of the conductive agent include powder, fiber, and the like. As the conductive agent, one type of these materials may be used alone, or two or more types may be used in combination. Further, these materials may be used in combination. For example, a composite material of carbon black and CNT may be used. Among these, carbon black is preferred from the viewpoint of electronic conductivity and coatability, and acetylene black is particularly preferred.

The content of the conductive agent in the active material layer 13 is preferably 1% by mass or more and 10% by mass or less, more preferably 3% by mass or more and 9% by mass or less. By setting the content of the conductive agent within the above range, the energy density of the stacked power storage element can be increased.

Examples of binders include fluororesins (polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), etc.), thermoplastic resins such as polyethylene, polypropylene, polyacrylic, polyimide, etc.; ethylene-propylene-diene rubber (EPDM), sulfone. Examples include elastomers such as chemically modified EPDM, styrene butadiene rubber (SBR), and fluororubber; polysaccharide polymers, and the like.

The binder content in the active material layer 13 is preferably 1% by mass or more and 10% by mass or less, more preferably 3% by mass or more and 9% by mass or less. By setting the content of the binder within the above range, the active material can be stably held.

Examples of the thickener include polysaccharide polymers such as carboxymethylcellulose (CMC) and methylcellulose. When the thickener has a functional group that reacts with lithium or the like, this functional group may be deactivated in advance by methylation or the like.

The filler is not particularly limited. Fillers include polyolefins such as polypropylene and polyethylene, inorganic oxides such as silicon dioxide, aluminum oxide, titanium dioxide, calcium oxide, strontium oxide, barium oxide, magnesium oxide, and aluminosilicate, magnesium hydroxide, calcium hydroxide, and water. Hydroxides such as aluminum oxide, carbonates such as calcium carbonate, poorly soluble ionic crystals such as calcium fluoride, barium fluoride, barium sulfate, nitrides such as aluminum nitride and silicon nitride, talc, montmorillonite, boehmite, zeolite , apatite, kaolin, mullite, spinel, olivine, sericite, bentonite, mica, and other materials derived from mineral resources, or artificial products thereof.

The active material layer 13 is made of typical nonmetal elements such as B, N, P, F, Cl, Br, I, Li, Na, Mg, Al, K, Ca, Zn, Ga, Ge, Sn, Sr, Ba, etc. Typical metal elements such as Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Mo, Zr, Ta, Hf, Nb, W, and other transition metal elements are used as active materials, conductive agents, binders, and thickeners. It may be contained as a component other than fillers.

As a method for producing an electrode, for example, an electrode mixture paste (positive electrode mixture paste or negative electrode mixture paste) is applied directly or through an intermediate layer to a part of the surface of rolled metal foil, and after drying, the necessary Roll pressing or the like is performed according to the conditions to form an active material layer (positive electrode active material layer or negative electrode active material layer). Then, the electrode is formed by cutting the rolled metal foil and active material layer into the shape of the electrode base material and the tab part so that the rolling direction of the rolled metal foil is along the protruding direction of the tab part and the long side direction of the electrode base material. You may. In addition, after forming the electrode base material and the tab part by cutting out the rolled metal foil at once so that the rolling direction of the rolled metal foil is along the protruding direction of the tab part and the long side direction of the electrode base material, the electrode base material and the tab part are cut out. An active material layer may be formed by applying the electrode mixture paste directly or through an intermediate layer to a part or the entire surface of the electrode base material and drying it. After drying, roll pressing or the like may be performed as necessary. The electrode mixture paste contains an active material, a conductive agent, a binder, and other optional components as necessary. The electrode mixture paste usually further contains a dispersion medium.

<Configuration of stacked energy storage element>
A stacked power storage element according to an embodiment of the present invention includes an electrode body having the above-mentioned positive electrode, the above-mentioned negative electrode, and a separator, an electrolyte, and a container containing the above-mentioned electrode body and electrolyte. At least one of the positive electrode, the negative electrode, or a combination thereof is an electrode for a stacked power storage element according to an embodiment of the present invention. The electrode body is a stacked type in which a plurality of positive electrodes and a plurality of negative electrodes are stacked with a separator in between. The electrolyte exists in the positive electrode, negative electrode, and separator. A non-aqueous electrolyte secondary battery (hereinafter also simply referred to as a "secondary battery") will be described as an example of a stacked power storage element.

The shape of the stacked power storage element of this embodiment is not particularly limited, and examples include a square battery, a flat battery, and the like.

FIG. 3 shows a stacked power storage element 1 as an example of a square battery. Note that this figure is a perspective view of the inside of the container. The stacked power storage element 1 includes a container 3, a lid 6 in the shape of an elongated rectangular plate that can close the elongated rectangular opening of the container 3, an electrode body 2 housed in the container 3, and a lid. 6, a positive electrode terminal 4 and a negative electrode terminal 5 are provided. The positive electrode terminal 4 is an electrode terminal electrically connected to the positive electrode of the electrode body 2 via the positive electrode lead 41, and the negative electrode terminal 5 is an electrode terminal electrically connected to the negative electrode of the electrode body 2 via the negative electrode lead 51. This is an electrode terminal.

In the laminated power storage element 1, the electrode body 2 is arranged so that the long side direction of the electrode base material 12 (the rolling direction R of the electrode base material 12 shown in FIG. 2) is along the vertical direction. The electrode body 2 is constructed by alternately stacking a plurality of positive electrodes and a plurality of negative electrodes, and disposing a plurality of separators between the positive electrodes and the negative electrodes. A positive electrode tab portion 42 is formed on the positive electrode and is integrally formed with the positive electrode base material and protrudes from the short side of the positive electrode base material. A negative electrode tab portion 52 is formed on the negative electrode and is integrally formed with the negative electrode base material and protrudes from the short side of the negative electrode base material. The positive electrode lead 41 is disposed above the electrode body 2 on the positive electrode tab portion 42 side, and the positive electrode terminal 4 and the positive electrode tab portion 42 are electrically connected via the positive electrode lead 41. The negative electrode lead 51 is disposed above the electrode body 2 on the negative electrode tab portion 52 side, and the negative electrode terminal 5 and the negative electrode tab portion 52 are electrically connected via the negative electrode lead 51. Specifically, the positive electrode lead 41 is connected to the positive electrode of the electrode body 2 by being joined to the positive electrode tab portion 42 of the electrode body 2 by welding or the like. Further, the negative electrode lead 51 is connected to the negative electrode of the electrode body 2 by being joined to the negative electrode tab portion 52 of the electrode body 2 by welding or the like.

The positive electrode tab portion 42 and the negative electrode tab portion 52 protrude vertically upward along the long side direction (the direction in which the long sides extend) of the electrode base material 12. The rolling direction R of the rolled metal foil constituting the positive electrode base material and the positive electrode tab portion 42 or the negative electrode base material and the negative electrode tab portion 52 is the protruding direction of the positive electrode tab portion 42 and the negative electrode tab portion 52 (the long side direction of the electrode base material 12). ), that is, along the vertical direction of the stacked power storage element 1.

(positive electrode and negative electrode)
At least one of the positive electrode and the negative electrode is an electrode for the stacked power storage element according to the embodiment of the present invention described above. When either the positive electrode or the negative electrode is an electrode other than the electrode for the stacked power storage element according to the embodiment of the present invention described above, a conventionally known electrode can be used as such an electrode. The structure of a conventionally known electrode includes a rectangular electrode base material made of rolled metal foil, a tab portion that is integrally formed with the electrode base material and protrudes from the short side of the electrode base material; The structure is the same as the electrode for the laminated power storage element according to the embodiment of the present invention described above, except that the protruding direction of the tab portion is along the rolling direction of the rolled metal foil. I can do it.

(Separator)
The separator can be appropriately selected from known separators. As the separator, for example, a separator consisting of only a base material layer, a separator in which a heat resistant layer containing heat resistant particles and a binder is formed on one or both surfaces of the base material layer, etc. can be used. Examples of the shape of the base material layer of the separator include woven fabric, nonwoven fabric, and porous resin film. Among these shapes, a porous resin film is preferred from the viewpoint of strength, and a nonwoven fabric is preferred from the viewpoint of liquid retention of the nonaqueous electrolyte. As the material for the base layer of the separator, polyolefins such as polyethylene and polypropylene are preferred from the viewpoint of shutdown function, and polyimide, aramid, etc. are preferred from the viewpoint of oxidative decomposition resistance. A composite material of these resins may be used as the base material layer of the separator.

The heat-resistant particles contained in the heat-resistant layer preferably have a mass loss of 5% or less when the temperature is raised from room temperature to 500°C in an air atmosphere of 1 atm, and the mass loss when the temperature is raised from room temperature to 800°C. is more preferably 5% or less. Inorganic compounds are examples of materials whose mass loss is less than a predetermined value. Examples of inorganic compounds include oxides such as iron oxide, silicon oxide, aluminum oxide, titanium oxide, zirconium oxide, calcium oxide, strontium oxide, barium oxide, magnesium oxide, and aluminosilicate; nitrides such as aluminum nitride and silicon nitride. carbonates such as calcium carbonate; sulfates such as barium sulfate; poorly soluble ionic crystals such as calcium fluoride, barium fluoride, barium titanate; covalent crystals such as silicon and diamond; talc, montmorillonite, boehmite, Examples include substances derived from mineral resources such as zeolite, apatite, kaolin, mullite, spinel, olivine, sericite, bentonite, and mica, or artificial products thereof. As the inorganic compound, these substances may be used alone or in combination, or two or more types may be used in combination. Among these inorganic compounds, silicon oxide, aluminum oxide, or aluminosilicate is preferable from the viewpoint of safety of the multilayer power storage element.

The porosity of the separator is preferably 80% by volume or less from the viewpoint of strength, and preferably 20% by volume or more from the viewpoint of discharge performance. Here, "porosity" is a value based on volume, and means a value measured with a mercury porosimeter.

A polymer gel composed of a polymer and a non-aqueous electrolyte may be used as the separator. Examples of the polymer include polyacrylonitrile, polyethylene oxide, polypropylene oxide, polymethyl methacrylate, polyvinyl acetate, polyvinylpyrrolidone, polyvinylidene fluoride, and the like. Use of polymer gel has the effect of suppressing liquid leakage. As a separator, a porous resin film or nonwoven fabric as described above and a polymer gel may be used in combination.

(Nonaqueous electrolyte)
The non-aqueous electrolyte can be appropriately selected from known non-aqueous electrolytes. A non-aqueous electrolyte may be used as the non-aqueous electrolyte. The nonaqueous electrolyte includes a nonaqueous solvent and an electrolyte salt dissolved in the nonaqueous solvent.

The non-aqueous solvent can be appropriately selected from known non-aqueous solvents. Examples of the non-aqueous solvent include cyclic carbonates, chain carbonates, carboxylic esters, phosphoric esters, sulfonic esters, ethers, amides, and nitriles. As the non-aqueous solvent, compounds in which some of the hydrogen atoms contained in these compounds are replaced with halogens may be used.

Examples of cyclic carbonates include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylene carbonate (VC), vinylethylene carbonate (VEC), chloroethylene carbonate, fluoroethylene carbonate (FEC), and difluoroethylene carbonate. (DFEC), styrene carbonate, 1-phenylvinylene carbonate, 1,2-diphenylvinylene carbonate, and the like. Among these, EC is preferred.

Examples of chain carbonates include diethyl carbonate (DEC), dimethyl carbonate (DMC), ethylmethyl carbonate (EMC), diphenyl carbonate, trifluoroethylmethyl carbonate, bis(trifluoroethyl) carbonate, and the like. Among these, EMC is preferred.

As the nonaqueous solvent, it is preferable to use a cyclic carbonate or a chain carbonate, and it is more preferable to use a cyclic carbonate and a chain carbonate together. By using a cyclic carbonate, it is possible to promote the dissociation of the electrolyte salt and improve the ionic conductivity of the non-aqueous electrolyte. By using chain carbonate, the viscosity of the non-aqueous electrolyte can be kept low. When a cyclic carbonate and a chain carbonate are used together, the volume ratio of the cyclic carbonate to the chain carbonate (cyclic carbonate: chain carbonate) is preferably in the range of, for example, 5:95 to 50:50.

The electrolyte salt can be appropriately selected from known electrolyte salts. Examples of electrolyte salts include lithium salts, sodium salts, potassium salts, magnesium salts, onium salts, and the like. Among these, lithium salts are preferred.

Examples of lithium salts include inorganic lithium salts such as LiPF ₆ , LiPO ₂ F ₂ , LiBF ₄ , LiClO ₄ , and LiN(SO ₂ F) ₂ , lithium bis(oxalate) borate (LiBOB), and lithium difluorooxalate borate (LiFOB). , lithium oxalate salts such as lithium bis(oxalate) difluorophosphate (LiFOP), LiSO ₃ CF ₃ , LiN(SO ₂ CF ₃ ) ₂ , LiN(SO ₂ C ₂ F ₅ ) ₂ , LiN(SO ₂ CF ₃ ) Examples include lithium salts having halogenated hydrocarbon groups such as (SO ₂ C ₄ F ₉ ), LiC (SO ₂ CF ₃ ) ₃ and LiC (SO ₂ C ₂ F ₅ ) ₃ . Among these, inorganic lithium salts are preferred, and LiPF ₆ is more preferred.

The content of the electrolyte salt in the nonaqueous electrolyte is preferably 0.1 mol/dm ³ or more and 2.5 mol/dm 3 or less, and 0.3 mol/dm ^{3 or} more and 2.0 mol/dm at 20° C. and 1 atmosphere. It is more preferably ³ or less, even more preferably 0.5 mol/dm ³ or more and 1.7 mol/dm ³ or less, particularly preferably 0.7 mol/dm ³ or more and 1.5 mol/dm ³ or less. By setting the content of the electrolyte salt within the above range, the ionic conductivity of the non-aqueous electrolyte can be increased.

The non-aqueous electrolyte may contain additives in addition to the non-aqueous solvent and electrolyte salt. Examples of additives include oxalates such as lithium bis(oxalate)borate (LiBOB), lithium difluorooxalateborate (LiFOB), and lithium bis(oxalate)difluorophosphate (LiFOP); lithium bis(fluorosulfonyl)imide ( imide salts such as LiFSI); aromatic compounds such as biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated products of terphenyl, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, and dibenzofuran; 2-fluorobiphenyl; Partial halides of the above aromatic compounds such as o-cyclohexylfluorobenzene and p-cyclohexylfluorobenzene; 2,4-difluoroanisole, 2,5-difluoroanisole, 2,6-difluoroanisole, 3,5-difluoroanisole, etc. halogenated anisole compounds; vinylene carbonate, methyl vinylene carbonate, ethyl vinylene carbonate, succinic anhydride, glutaric anhydride, maleic anhydride, citraconic anhydride, glutaconic anhydride, itaconic anhydride, cyclohexanedicarboxylic anhydride; ethylene sulfite, Propylene sulfite, dimethyl sulfite, methyl methanesulfonate, busulfan, methyl toluenesulfonate, dimethyl sulfate, ethylene sulfate, sulfolane, dimethyl sulfone, diethyl sulfone, dimethyl sulfoxide, diethyl sulfoxide, tetramethylene sulfoxide, diphenyl sulfide, 4,4'- Bis(2,2-dioxo-1,3,2-dioxathiolane), 4-methylsulfonyloxymethyl-2,2-dioxo-1,3,2-dioxathiolane, thioanisole, diphenyl disulfide, dipyridinium disulfide, 1, 3-propene sultone, 1,3-propane sultone, 1,4-butane sultone, 1,4-butene sultone, perfluorooctane, tristrimethylsilyl borate, tristrimethylsilyl phosphate, tetrakistrimethylsilyl titanate, lithium monofluorophosphate, difluoro Examples include lithium phosphate. These additives may be used alone or in combination of two or more.

The content of the additive contained in the nonaqueous electrolyte is preferably 0.01% by mass or more and 10% by mass or less, and 0.1% by mass or more and 7% by mass or less based on the mass of the entire nonaqueous electrolyte. It is more preferable if it is present, more preferably from 0.2% by mass to 5% by mass, and particularly preferably from 0.3% by mass to 3% by mass. By setting the content of the additive within the above range, capacity retention performance or cycle performance after high-temperature storage can be improved, and safety can be further improved.

A solid electrolyte may be used as the non-aqueous electrolyte, or a non-aqueous electrolyte and a solid electrolyte may be used together.

The solid electrolyte can be selected from any material that has ionic conductivity, such as lithium, sodium, and calcium, and is solid at room temperature (for example, 15° C. to 25° C.). Examples of solid electrolytes include sulfide solid electrolytes, oxide solid electrolytes, oxynitride solid electrolytes, polymer solid electrolytes, gel polymer electrolytes, and the like.

Examples of the sulfide solid electrolyte in the case of a lithium ion secondary battery include Li ₂ SP ₂ S ₅ , LiI-Li ₂ SP ₂ S ₅ , Li ₁₀ Ge-P ₂ S ₁₂ , and the like.

<Configuration of power storage device>
The stacked power storage element of this embodiment can be used as a power source for automobiles such as electric vehicles (EVs), hybrid vehicles (HEVs), and plug-in hybrid vehicles (PHEVs), power sources for electronic devices such as personal computers and communication terminals, or power storage. The power storage device can be installed in a power source or the like as a power storage device including a power storage unit (battery module) configured by aggregating a plurality of stacked power storage elements. In this case, the technology of the present invention may be applied to at least one stacked power storage element included in the power storage device.

FIG. 4 shows an example of a power storage device 30 in which a power storage unit 20 in which two or more electrically connected stacked power storage elements 1 are assembled is further assembled. The power storage device 30 may include a bus bar (not shown) that electrically connects two or more stacked power storage elements 1, a bus bar (not shown) that electrically connects two or more power storage units 20, etc. good. The power storage unit 20 or the power storage device 30 may include a state monitoring device (not shown) that monitors the state of one or more stacked power storage elements 1.

<Method for manufacturing stacked energy storage element>
A method for manufacturing the stacked power storage element of this embodiment can be appropriately selected from known methods. The manufacturing method includes, for example, preparing an electrode body, preparing an electrolyte, and accommodating the electrode body and the electrolyte in a container. Preparing the electrode body includes preparing a positive electrode and a negative electrode, at least one of which includes the electrode base material and the tab portion, and forming the electrode body by stacking the positive electrode and the negative electrode with a separator in between. .

The method of storing the electrolyte in the container can be appropriately selected from known methods. For example, when a non-aqueous electrolyte is used as the electrolyte, the injection port may be sealed after the non-aqueous electrolyte is injected through an injection port formed in the container.
<Other embodiments>
Note that the stacked power storage element of the present invention is not limited to the above embodiments, and various changes may be made without departing from the gist of the present invention. For example, the configuration of one embodiment can be added to the configuration of another embodiment, and a part of the configuration of one embodiment can be replaced with the configuration of another embodiment or a known technique. Additionally, some of the configurations of certain embodiments may be deleted. Furthermore, well-known techniques can be added to the configuration of a certain embodiment.

In the above embodiment, the case where the stacked energy storage element is used as a chargeable/dischargeable non-aqueous electrolyte secondary battery (for example, a lithium ion secondary battery) has been described, but the type, shape, size, capacity, etc. of the stacked energy storage element, etc. is optional. The present invention can also be applied to capacitors such as various secondary batteries, electric double layer capacitors, and lithium ion capacitors.

In the above embodiment, an electrode body in which a positive electrode and a negative electrode are laminated with a separator interposed therebetween has been described, but the electrode body does not need to include a separator. For example, the positive electrode and the negative electrode may be in direct contact with each other with a non-conductive layer formed on the active material layer of the positive electrode or the negative electrode. Furthermore, the laminated power storage element of the present invention can also be applied to a laminated power storage element in which the electrolyte is an electrolyte other than a non-aqueous electrolyte (an electrolyte containing water as a solvent).

INDUSTRIAL APPLICABILITY The present invention can be applied to a stacked power storage element used as a power source for electronic devices such as personal computers and communication terminals, and automobiles, and electrodes provided therein.

1 Laminated power storage element 2 Electrode body 3 Container 4 Positive electrode terminal 5 Negative electrode terminal 6 Lid body 10 Electrode 11 Tab portion 12 Electrode base material 13 Active material layer 18 Short side of electrode base material 20 Power storage unit 30 Power storage device 41 Positive electrode lead 42 Positive electrode Tab portion 51 Negative electrode lead 52 Negative electrode tab portion R Rolling direction of rolled metal foil

Claims (2)

a rectangular electrode base material made of rolled metal foil;
a tab portion formed integrally with the electrode base material and protruding from the short side of the electrode base material,
An electrode for a laminated power storage element, wherein the protruding direction of the tab portion is along the rolling direction of the rolled metal foil. A stacked power storage element comprising the electrode according to claim 1.

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