JP7444029B2 - Energy storage cells and energy storage devices - Google Patents

Description

The present disclosure relates to a power storage cell and a power storage device.

Patent Document 1 describes a secondary battery formed by laminating an electrode in which an active material layer is formed on a current collector and an electrolyte layer disposed between the electrodes, in which the active material layer is disposed on the outer periphery of the electrolyte layer. It is described that the seal portion liquid-tightly seals between adjacent current collectors in the stacking direction.

Japanese Patent Application Publication No. 2017-16825

In the secondary battery described in Patent Document 1, in which a plurality of cell layers are stacked in one direction, if the current collector of the cell layer arranged at the top in the stacking direction is damaged, the current collector is sealed inside. The electrolyte may leak to the outside and adhere to the outer surface of the unit cell layer arranged at the bottom in the stacking direction. If some of the electrolyte adhering to the outer surface flows to the outer surface of the seal, and specific components in the electrolyte react with moisture in the air on the outer surface of the seal, the seal may be damaged. Therefore, the sealing performance of the secondary battery may deteriorate. Furthermore, if the thickness of the current collector is made thinner in order to increase the energy density of the secondary battery, another problem arises in that it is easily damaged when internal pressure increases or during transportation.

An object of the present disclosure is to provide a power storage cell and a power storage device that can reinforce a current collector while suppressing deterioration in sealing performance.

A power storage cell according to one aspect of the present disclosure includes a first current collector, a positive electrode having a positive electrode active material layer provided on one side of the first current collector, a second current collector, and a second current collector. A negative electrode provided on one side of the body and having a negative electrode active material layer facing a positive electrode active material layer with a separator in between, and an edge of the first current collector and an edge of the second current collector. , a sealing part that seals the space between the first current collector and the second current collector, an outer periphery of the sealing part, an edge of the first current collector adjacent to the outer periphery, and a second a tape extending in a direction intersecting the opposing direction of the positive electrode active material layer and the negative electrode active material layer while collectively covering the edge of the current collector, the tape comprising a first tape portion that covers the outer peripheral portion; , a second tape portion that covers the edge of the first current collector, and a third tape portion that covers the edge of the second current collector, and the outer edge of the negative electrode active material layer when viewed from the opposing direction. is located outside the outer edge of the positive electrode active material layer, and at least one inner edge of the second tape portion and the third tape portion is located between the outer edge of the positive electrode active material layer and the negative electrode active material layer. It is located between the outer edge.

In the above-mentioned electricity storage cell, the tape collectively covers the outer periphery of the sealing portion, the edge of the first current collector, and the edge of the second current collector. This protects the sealing portion from being exposed to the outside. Therefore, even if the electrolytic solution leaks from the upper storage cell and reacts with moisture in the air to generate hydrofluoric acid, damage to the sealing portion is suppressed, and deterioration in sealing performance is suppressed. Moreover, at least one inner edge of the second tape portion covering the edge of the first current collector and the inner edge of the third tape portion covering the edge of the second current collector is , located between the outer edge of the positive electrode active material layer and the outer edge of the negative electrode active material layer. As a result, at least one of the first current collector and the second current collector is covered and reinforced with the tape to the inner side of the outer edge of the negative electrode active material layer. Furthermore, since the tape is provided so as not to overlap both the positive electrode active material layer and the negative electrode active material layer, it is suppressed that surface pressure is less likely to be applied to the positive electrode active material layer and the negative electrode active material layer.

The one inner edge may be located on the other surface of the thinner current collector of the first current collector and the second current collector. In this case, the current collector, which is more easily torn, can be reinforced.

The inner edge of the second tape portion and the inner edge of the third tape portion may be located between the outer edge of the positive electrode active material layer and the outer edge of the negative electrode active material layer when viewed from the opposing direction. In this case, both the first current collector and the second current collector are covered and reinforced with tape to the inside of the outer edge of the negative electrode active material layer.

The sealing portion may be formed in a rectangular frame shape when viewed from the opposite direction, and the tape may be provided on at least one side of the sealing portion. In this case, it is possible to suppress deterioration in sealing performance on at least one side of the sealing portion.

A power storage device according to the present disclosure includes a stacked body in which a plurality of power storage cells are stacked, and at least one of the plurality of power storage cells is the above-described power storage cell.

In the above power storage device, since the laminate includes at least one of the above power storage cells, the current collector can be reinforced while suppressing deterioration in sealing performance of the power storage cell.

According to the present disclosure, it is possible to provide a power storage cell and a power storage device that can suppress deterioration in sealing performance.

FIG. 1 is a schematic cross-sectional view showing a power storage device according to an embodiment. FIG. 2 is a schematic cross-sectional view of the electricity storage cell shown in FIG. 1. FIG. 3 is a plan view of the electricity storage cell shown in FIG. 1.

Embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. In the description of the drawings, the same reference numerals are used for the same or equivalent elements, and redundant description will be omitted.

FIG. 1 is a schematic cross-sectional view showing a power storage device according to an embodiment. A power storage device 1 shown in FIG. 1 is, for example, a power storage module used in batteries of various vehicles such as a forklift, a hybrid vehicle, and an electric vehicle. The power storage device 1 is, for example, a secondary battery such as a nickel-metal hydride secondary battery or a lithium ion secondary battery. Power storage device 1 may be an electric double layer capacitor or an all-solid-state battery. In this embodiment, a case is illustrated in which power storage device 1 is a lithium ion secondary battery.

Power storage device 1 includes a cell stack 3 (laminated body) in which a plurality of power storage cells 2 are stacked. FIG. 2 is a schematic cross-sectional view of the electricity storage cell shown in FIG. 1. FIG. 3 is a plan view of the electricity storage cell shown in FIG. 1. As shown in FIGS. 1 to 3, each power storage cell 2 includes a positive electrode 11, a negative electrode 12, a separator 13, a sealing part 14, and a tape 15. The positive electrode 11 and the negative electrode 12 are arranged facing each other. The direction D in which the positive electrode 11 and the negative electrode 12 face each other coincides with the direction in which the plurality of storage cells 2 are stacked. The positive electrode 11 and the negative electrode 12 are, for example, rectangular electrodes when viewed from the opposing direction D. The opposing direction D is, for example, the direction of gravity, and the positive electrode 11 is disposed above the negative electrode 12 in the direction of gravity. The positive electrode 11 may be placed below the negative electrode 12 in the direction of gravity.

The positive electrode 11 includes a current collector 21 (first current collector) and a positive electrode active material layer 23. The current collector 21 has a first surface 21a and a second surface 21b facing opposite to each other, and an edge 21c. A positive electrode active material layer 23 is provided on the first surface 21a. The positive electrode active material layer 23 is not provided on the second surface 21b. The positive electrode active material layer 23 is not provided on the edge 21c on either the first surface 21a side or the second surface 21b side. In other words, the first surface 21a has a region in the edge portion 21c where the positive electrode active material layer 23 is not provided. The edge portion 21c is located outside the region of the current collector 21 where the positive electrode active material layer 23 is provided when viewed from the opposing direction D.

The negative electrode 12 includes a current collector 22 (second current collector) and a negative electrode active material layer 24. The current collector 22 has a first surface 22a and a second surface 22b facing oppositely to each other, and an edge 22c. A negative electrode active material layer 24 is provided on the first surface 22a. The negative electrode active material layer 24 faces the positive electrode active material layer 23 in the facing direction D with the separator 13 in between. The negative electrode active material layer 24 is not provided on the second surface 22b. The negative electrode active material layer 24 is not provided on the edge 22c on either the first surface 22a side or the second surface 22b side. In other words, the first surface 22a has a region in the edge portion 22c where the negative electrode active material layer 24 is not provided. The edge 22c is located outside the region of the current collector 22 where the negative electrode active material layer 24 is provided when viewed from the opposing direction D.

The positive electrode 11 and the negative electrode 12 are arranged such that the positive electrode active material layer 23 and the negative electrode active material layer 24 face each other in the facing direction D. In this embodiment, the positive electrode active material layer 23 and the negative electrode active material layer 24 are both formed in a rectangular shape when viewed from the opposing direction D. The negative electrode active material layer 24 is formed to be one size larger than the positive electrode active material layer 23. The negative electrode active material layer 24 has a larger coating area than the positive electrode active material layer 23. When viewed from the opposing direction D, the outer edge 24a of the negative electrode active material layer 24 is located outside the outer edge 23a of the positive electrode active material layer 23.

By stacking the plurality of power storage cells 2 such that the second surface 21b of the current collector 21 of one power storage cell 2 and the second surface 22b of the current collector 22 of the other power storage cell 2 are in contact with each other, , a cell stack 3 is configured. Thereby, the plurality of power storage cells 2 are electrically connected in series. In the power storage cells 2, 2 that are adjacent to each other in the stacking direction, the current collector 21 of one power storage cell 2 and the current collector 22 of the other power storage cell 2 are in contact with each other.

In the cell stack 3, the current collectors 21 and 22 of one power storage cell 2 that are adjacent to each other in the stacking direction and the current collectors 22 of the other power storage cells 2 are combined into one current collector 21 and current collector 22 that are in contact with each other. A pseudo bipolar electrode 10 serving as a current collector is formed. A termination electrode (in this embodiment, a positive termination electrode) including a current collector 21 is arranged at one end of the cell stack 3 in the stacking direction. A termination electrode (in this embodiment, a negative termination electrode) including a current collector 22 is arranged at the other end of the cell stack 3 in the stacking direction.

The current collectors 21 and 22 are chemically inert electrical conductors that keep current flowing through the positive electrode active material layer 23 and the negative electrode active material layer 24 during discharging or charging of the lithium ion secondary battery. As the material constituting the current collectors 21 and 22, for example, a metal material, a conductive resin material, a conductive inorganic material, etc. can be used. Examples of the conductive resin material include resins in which a conductive filler is added to a conductive polymer material or a non-conductive polymer material as necessary. The current collectors 21 and 22 may include multiple layers including one or more layers containing the metal material or conductive resin material described above. A coating layer may be formed on the surfaces of the current collectors 21 and 22 by a known method such as plating or spray coating.

The current collectors 21 and 22 may be formed in, for example, a plate shape, a foil shape, a sheet shape, a film shape, a mesh shape, or the like. When the current collectors 21 and 22 are made of metal foil, for example, aluminum foil, copper foil, nickel foil, titanium foil, stainless steel foil, or the like is used. The current collectors 21 and 22 may be alloy foil or clad foil made of the constituent material of the metal foil described above. When the current collectors 21 and 22 are foil-shaped, the thickness of the current collectors 21 and 22 may be in the range of 1 μm or more and 100 μm or less. In this embodiment, the current collector 21 is an aluminum foil with a thickness of 50 μm, and the current collector 22 is a copper foil with a thickness of 15 μm. Current collector 21 is thicker than current collector 22.

The positive electrode active material layer 23 includes a positive electrode active material that can insert and release charge carriers such as lithium ions. Examples of the positive electrode active material include composite oxides, metallic lithium, and sulfur. The composition of the composite oxide includes, for example, at least one of iron, manganese, titanium, nickel, cobalt, and aluminum and lithium. Examples of the composite oxide include olivine-type lithium iron phosphate (LiFePO ₄ ), LiCoO ₂ , LiNiMnCoO ₂ , and the like.

The negative electrode active material layer 24 includes a negative electrode active material that can insert and release charge carriers such as lithium ions. Examples of negative electrode active materials include graphite, artificial graphite, highly oriented graphite, mesocarbon microbeads, carbon such as hard carbon and soft carbon, metal compounds, elements that can be alloyed with lithium or their compounds, boron-added carbon, etc. Can be mentioned. Examples of elements that can be alloyed with lithium include silicon and tin.

The positive electrode active material layer 23 and the negative electrode active material layer 24 may contain a binder and a conductive aid in addition to the active material. The binder plays the role of binding the active materials or conductive aids to each other and maintaining the conductive network in the electrode. As a binder, fluororesins such as polyvinylidene fluoride, polytetrafluoroethylene, and fluororubber, thermoplastic resins such as polypropylene and polyethylene, imide resins such as polyimide and polyamideimide, alkoxysilyl group-containing resins, and polyacrylics are used. Examples include acids, acrylic resins such as polymethacrylic acid, styrene-butadiene rubber, carboxymethyl cellulose, alginates such as sodium alginate and ammonium alginate, water-soluble cellulose ester crosslinked products, and starch-acrylic acid graft polymers. These binders may be used alone or in combination. The conductive aid is a conductive material such as acetylene black, carbon black, graphite, etc., and can improve electrical conductivity. For example, N-methyl-2-pyrrolidone or the like is used as the viscosity adjusting solvent.

In order to form the positive electrode active material layer 23 and the negative electrode active material layer 24 on the first surfaces 21a and 22a, conventional methods such as a roll coating method, a die coating method, a dip coating method, a doctor blade method, a spray coating method, and a curtain coating method can be used. A known method is used. Specifically, an active material, a solvent, and, if necessary, a binder and a conductive additive are mixed to produce a slurry-like active material layer-forming composition, and the active material layer-forming composition is mixed into a slurry. After coating on one side 21a and 22a, it is dried. Solvents are, for example, N-methyl-2-pyrrolidone, methanol, methyl isobutyl ketone, water. In order to increase the electrode density, the dried material may be compressed.

Separator 13 is placed between positive electrode 11 and negative electrode 12 . The separator 13 is a member that separates the adjacent positive electrode 11 and negative electrode 12 when the storage cells 2 are stacked, thereby preventing an electrical short circuit due to contact between the two electrodes, and allowing charge carriers such as lithium ions to pass through. Separator 13 is arranged between positive electrode active material layer 23 and negative electrode active material layer 24 that face each other.

The separator 13 has a rectangular shape that is one size larger than the positive electrode active material layer 23 and the negative electrode active material layer 24 and one size smaller than the current collectors 21 and 22 when viewed from the opposing direction D. The end 13a, which is the outer peripheral edge of the separator 13, is closer to the edges 21c and 22c of the current collectors 21 and 22 than the outer peripheral edges of the positive electrode active material layer 23 and the negative electrode active material layer 24, when viewed from the opposing direction D. It is located in The end portion 13a of the separator 13 does not overlap with either the positive electrode active material layer 23 or the negative electrode active material layer 24 when viewed from the opposing direction D.

The separator 13 is formed, for example, in a sheet shape. The separator 13 is, for example, a porous sheet or nonwoven fabric containing a polymer that absorbs and retains electrolyte. Examples of the material constituting the separator 13 include polypropylene, polyethylene, polyolefin, and polyester. The separator 13 may have a single layer structure or a multilayer structure. In the case of a multilayer structure, the separator 13 includes, for example, a base material layer and a pair of adhesive layers, and may be adhesively fixed to the positive electrode active material layer 23 and the negative electrode active material layer 24 by the pair of adhesive layers. Separator 13 may include a ceramic layer serving as a heat-resistant layer. The separator 13 may be reinforced with a vinylidene fluoride resin compound.

Examples of the electrolyte impregnated into the separator 13 include a liquid electrolyte (electrolyte) containing a nonaqueous solvent and an electrolyte salt dissolved in the nonaqueous solvent, or a polymer gel electrolyte containing an electrolyte held in a polymer matrix. can be mentioned. When the separator 13 is impregnated with an electrolytic solution, the electrolyte salt may be LiClO ₄ , LiAsF ₆ , LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiN(FSO ₂ ) ₂ , LiN(CF ₃ SO ₂ ) ₂ or the like. Known lithium salts can be used. Further, as the nonaqueous solvent, known solvents such as cyclic carbonates, cyclic esters, chain carbonates, chain esters, and ethers can be used. Note that two or more of these known solvent materials may be used in combination.

The sealing part 14 is a resin member that seals the space S between the current collector 21 and the current collector 22. The sealing portion 14 is located between the edge 21c of the current collector 21 and the edge 22c of the current collector 22 so as to surround the positive electrode active material layer 23 and the negative electrode active material layer 24 when viewed from the opposing direction D. It is located. In the electricity storage cell 2, a space S is defined by the current collector 21, the current collector 22, and the sealing part 14. The space S accommodates an electrolytic solution (not shown). The sealing part 14 is arranged between the current collector 21 and the current collector 22, and thereby functions also as a spacer that maintains the distance between the current collector 21 and the current collector 22.

The sealing part 14 is adhered (welded) to the first surface 21a side of the edge 21c of the current collector 21 and to the first surface 22a side of the edge 22c of the current collector 22. The sealing portion 14 is spaced apart from the positive electrode active material layer 23 and the negative electrode active material layer 24 when viewed from the facing direction D. The first surface 21 a has a region exposed from the positive electrode active material layer 23 and the sealing part 14 . The first surface 22 a has a region exposed from the negative electrode active material layer 24 and the sealing part 14 .

The sealing portion 14 is formed into a rectangular frame shape having four sides when viewed from the opposing direction D. The sealing portion 14 is formed to have a rectangular cross section. The sealing portion 14 has a first surface 14a and a second surface 14b facing oppositely to each other, and an inner peripheral surface 14c and an outer peripheral surface 14d facing oppositely to each other. The first surface 14a faces the first surface 21a and is bonded (welded) to the first surface 21a. An end portion of the first surface 14 a on the outer circumferential surface 14 d side is exposed from the current collector 21 . The second surface 14b faces the first surface 22a and is adhered (welded) to the first surface 22a. An end portion of the second surface 14b on the outer peripheral surface 14d side is exposed from the current collector 22.

The inner circumferential surface 14c and the outer circumferential surface 14d extend along the opposing direction D so as to connect the first surface 14a and the second surface 14b, respectively. The inner peripheral surface 14c faces the space S. The outer circumferential surface 14d faces the outside of the power storage cell 2. When viewed from the opposing direction D, the outer circumferential surface 14d is located outside of the outer edge 21d of the current collector 21 and the outer edge 22d of the current collector 22. That is, the sealing part 14 is provided so that the outer peripheral surface 14d protrudes from the current collectors 21 and 22. By sandwiching the end portion 13a of the separator 13 between the sealing portion 14 and the first surface 22a of the current collector 22, the position of the separator 13 inside the power storage cell 2 is fixed.

The sealing portion 14 has electrical insulation properties and electrolyte resistance. The sealing portion 14 is made of, for example, a resin material having electrolyte resistance such as acid-modified polyethylene (acid-modified PE), acid-modified polypropylene (acid-modified PP), polyethylene (PE), or polypropylene. In this embodiment, the sealing portion 14 is made of acid-modified polyethylene or acid-modified polypropylene. Acid-modified polyethylene and acid-modified polypropylene adhere to metals more easily than non-acid-modified polyethylene and polypropylene. Therefore, the adhesive strength of the sealing portion 14 to the current collectors 21 and 22 can be improved, and sealing performance can be improved.

The tape 15 is a band-shaped member having electrical insulation properties. The tape 15 intersects in the opposing direction D while collectively covering the outer peripheral part 14e of the sealing part 14, and the edge 21c of the current collector 21 and the edge 22c of the current collector 22 adjacent to the outer peripheral part 14e. extending in the direction. The outer peripheral portion 14e is a portion including the outer peripheral surface 14d. The tape 15 is provided continuously on the outer peripheral portion 14e and the edges 21c and 22c. The tape 15 may be made of a material having electrolyte resistance and heat resistance. The tape 15 has, for example, a two-layer structure in which an adhesive layer is arranged on one side of a base material layer, and one side on which the adhesive layer is provided is an adhesive surface. The base material layer is made of polyimide (PI), for example. When the base material layer is made of a material having a waterproof function, the waterproof function in the vicinity of the sealing portion 14 of the electricity storage cell 2 can be improved. The adhesive layer is made of, for example, a silicon adhesive.

The tape 15, which is a band-shaped member, has a width of the outer peripheral portion 14e of the sealing portion 14, assuming that the width is the length in the direction orthogonal to the direction along the sides of the current collectors 21 and 22 before being attached to the electricity storage cell 2. It also has a width that can cover the edge 21c of the current collector 21 and the edge 22c of the current collector 22. When the tape 15 is attached to the electricity storage cell 2, the tape 15 has a tape portion 15a that covers the outer peripheral portion 14e, a tape portion 15b that covers the edge 21c, and a tape portion 15c that covers the edge 22c as parts in the width direction. have. Tape portion 15a is arranged between tape portion 15b and tape portion 15c. Tape portion 15a is connected to tape portion 15b and tape portion 15c, respectively.

When viewed from the opposing direction D, the tape 15 is provided on at least one side of the rectangular frame-shaped sealing part 14. The tape 15 collectively covers the outer peripheral portion 14e of the sealing portion 14, the edge 21c of the current collector 21, and the edge 22c of the current collector 22 on at least one side of the sealing portion 14. That is, at least one side of the rectangular frame-shaped sealing part 14 is covered with the current collectors 21 and 22 and the tape 15, so that it is not exposed to the outside. In this embodiment, the tape 15 is continuously provided on the four sides of the rectangular frame-shaped sealing part 14.

The tape portion 15b is provided on the second surface 21b of the current collector 21. The inner edge 15d of the tape portion 15b constitutes one end of the tape 15 in the width direction. The inner edge 15d is located inside the outer edge 21d of the current collector 21 when viewed from the opposing direction D. The tape portion 15c is provided on the second surface 22b of the current collector 22. The inner edge 15e of the tape portion 15c constitutes the other end of the tape 15 in the width direction. The inner edge 15e is located inside the outer edge 22d of the current collector 22 when viewed from the opposing direction D. The inner edge 15d and the inner edge 15e are located at least outside the outer edge 23a of the positive electrode active material layer 23 (on the edge side of the current collectors 21 and 22) when viewed from the opposing direction D.

At least one of the inner edges 15d and 15e is located between the outer edge 23a of the positive electrode active material layer 23 and the outer edge 24a of the negative electrode active material layer 24 when viewed from the opposing direction D. In this embodiment, when viewed from the opposing direction D, only the inner edge 15e is located between the outer edges 23a and 24a, and the inner edge 15d is located outside of the outer edge 24a. When viewed from the facing direction D, the tape 15 overlaps with the negative electrode active material layer 24 having a larger coating area among the positive electrode active material layer 23 and the negative electrode active material layer 24, and the positive electrode active material layer having a smaller coating area. It does not overlap with 23.

Since the current collector 22 is made of a thin metal foil, there is a risk that it may be torn due to external force during transportation, for example. In particular, when comparing the area in the current collector 22 where the negative electrode active material layer 24 and the sealing part 14 are not provided with the area in the current collector 22 where the negative electrode active material layer 24 and the sealing part 14 are provided, Breakage is likely to occur in areas where the negative electrode active material layer 24 and the sealing portion 14 are not provided. By providing the tape 15 on the current collector 22, these areas can be reinforced. As described above, the current collector 22 is made of metal foil that is thinner than the current collector 21. Therefore, in this embodiment, the tape 15 is provided to at least reinforce the current collector 22.

Power storage device 1 further includes, for example, a restraining member that applies a restraining load to cell stack 3 in the stacking direction. Thereby, in the cell stack 3, the state in which the plurality of power storage cells 2 are stacked is stably maintained.

As explained above, in the electricity storage cell 2, the strip-shaped tape 15 collectively covers the outer circumferential portion 14e, the edge portion 21c, and the edge portion 22c of the sealing portion 14. Thereby, the sealing part 14 is protected without being exposed to the outside. In the power storage device 1, the electrolyte may leak from the upper power storage cells 2 in the direction of gravity and adhere to the lower power storage cells 2. If the band-shaped tape 15 is not provided, and some of the electrolyte that leaks out from the upper storage cell 2 adheres to the sealing part 14 of the lower storage cell 2, the electrolyte will mix with moisture in the air. The reaction may generate, for example, hydrofluoric acid, which may damage the sealing portion 14 from the outside. In the electricity storage cell 2 of this embodiment, the band-shaped tape 15 is provided to prevent the sealing part 14 from being exposed to the outside, so that if the electrolyte leaks from the upper electricity storage cell 2 to the outside of the electricity storage cell 2. Even if this occurs, the electrolytic solution will not adhere to the sealing portion 14 of the lower storage cell 2. That is, damage to the sealing portions 14 of other power storage cells 2 due to the electrolyte leaking to the outside of the power storage cells 2 is suppressed. As a result, deterioration in sealing performance of power storage device 1 is suppressed.

If electrolyte leaks from a certain energy storage cell 2 to the outside of the energy storage cell 2, the electrolyte may flow along the side of the energy storage device 1, and a short circuit (liquid circuit) may occur between adjacent energy storage cells 2 through the electrolyte. . In the electricity storage cell 2, the edge 21c of the current collector 21 and the edge 22c of the current collector 22 are covered with the insulating tape 15, so that the insulation distance can be extended. Therefore, liquid junctions through the electrolyte can also be suppressed.

The inner edge 15e of the tape portion 15c is located between the outer edge 23a and the outer edge 24a when viewed from the opposing direction D. Thereby, the current collector 22 is covered and reinforced by the tape 15 to the inside of the outer edge 24a. By covering a wider area of the current collector 22 with the tape 15, the current collector 22 can be reinforced. By the way, when the tape 15 is provided in a region overlapping with both the positive electrode active material layer 23 and the negative electrode active material layer 24 when viewed from the facing direction D, the thickness of the portion where the tape 15 is provided in the stacking direction is locally Therefore, when a plurality of storage cells 2 are stacked and a restraining load is applied from both ends in the stacking direction using a restraining member (not shown), the entire positive electrode active material layer 23 and negative electrode active material layer 24 have a uniform surface. It becomes difficult to apply pressure. In the electricity storage cell 2 of this embodiment, the inner edge 15e of the tape 15 is located outside the outer edge 23a of the positive electrode active material layer 23 when viewed from the opposing direction D, and the inner edge 15e of the tape 15 is located outside the outer edge 23a of the positive electrode active material layer 23 and It is not provided in an area that overlaps with both. Therefore, when a plurality of storage cells 2 are stacked and a restraining load is applied from both ends in the stacking direction using a restraining member (not shown), it is difficult to apply uniform surface pressure to the entire positive electrode active material layer 23 and negative electrode active material layer 24. It is suppressed from becoming.

The inner edge 15e of the tape 15 is located on the second surface 22b of the current collector 22, which is thinner among the current collectors 21 and 22. Thereby, the current collector 22, which is more easily torn, can be reinforced, so damage to the power storage cell 2 can be more effectively suppressed.

The sealing part 14 is formed in a rectangular frame shape when viewed from the opposing direction D, and the tapes 15 are provided on the four sides of the sealing part 14. Therefore, it is possible to suppress deterioration in sealing performance on all four sides of the sealing portion 14.

Power storage device 1 includes a cell stack 3 in which a plurality of power storage cells 2 are stacked. Therefore, in the power storage device 1, the current collector 21 can be reinforced while suppressing the deterioration of the sealing performance of the power storage cell 2.

The present disclosure is not limited to the above embodiments. For example, current collector 21 may be thinner than current collector 22. In this case, the inner edge 15d of the tape 15 instead of the inner edge 15e of the tape 15 is located between the outer edge 23a of the positive electrode active material layer 23 and the outer edge 24a of the negative electrode active material layer 24 when viewed from the opposing direction D. Good too. Thereby, the current collector 21, which is more easily torn, can be reinforced.

The inner edges 15d and 15e of the insulating tape 15 may be located between the outer edge 23a of the positive electrode active material layer 23 and the outer edge 24a of the negative electrode active material layer 24 when viewed from the opposing direction D. In this case, both the current collector 21 and the current collector 22 are covered and reinforced with the tape 15 to the inside of the outer edge 23a. In addition, liquid junctions through the electrolyte are further suppressed.

The tape 15 may be constructed by combining two or more tapes. For example, one wide tape 15 may be configured by arranging two tapes in the width direction. In this case, by overlapping parts of the two tapes in the width direction, the two tapes can be integrated without any gaps.

In the power storage device 1, the cell stack 3 only needs to have at least one power storage cell 2, and for example, one power storage cell 2 and a power storage cell not provided with the tape 15 may be stacked. . Even in this case, the current collector 21 can be reinforced in at least one electricity storage cell 2 while suppressing deterioration in sealing performance.

DESCRIPTION OF SYMBOLS 1... Power storage device, 2... Energy storage cell, 3... Cell stack (laminate), 11... Positive electrode, 12... Negative electrode, 13... Separator, 14... Sealing part, 14e... Outer peripheral part, 15... Tape, 15d... Inner edge, 15e... Inner edge, 21... Current collector, 21a... First surface, 21b... Second surface, 21d... Outer edge, 22... Current collector, 22a... First surface, 22b... Second surface, 22d... Outer edge, 23... Positive electrode active material layer, 23a... outer edge, 24... negative electrode active material layer, 24a... outer edge, S... space.

Claims (5)

a positive electrode having a first current collector and a positive electrode active material layer provided on one side of the first current collector;
a second current collector; and a negative electrode having a negative electrode active material layer provided on one side of the second current collector and facing the positive electrode active material layer with a separator interposed therebetween;
a sealing part disposed between an edge of the first current collector and an edge of the second current collector, and sealing a space between the first current collector and the second current collector; ,
The positive electrode active material layer and the negative electrode active material layer are coated while collectively covering the outer peripheral part of the sealing part, the edge of the first current collector, and the edge of the second current collector adjacent to the outer peripheral part. a tape extending in a direction intersecting the opposing direction of the material layers;
The tape includes a first tape portion that covers the outer peripheral portion, a second tape portion that covers the edge of the first current collector, and a third tape portion that covers the edge of the second current collector. have,
When viewed from the opposing direction, the outer edge of the negative electrode active material layer is located outside the outer edge of the positive electrode active material layer, and is located outside of at least the inner edge of the second tape portion and the inner edge of the third tape portion. one inner edge is located between the outer edge of the positive electrode active material layer and the outer edge of the negative electrode active material layer,
Electricity storage cell. The one inner edge is located on the other surface of the thinner current collector of the first current collector and the second current collector,
The electricity storage cell according to claim 1. The inner edge of the second tape portion and the inner edge of the third tape portion are located between the outer edge of the positive electrode active material layer and the outer edge of the negative electrode active material layer, when viewed from the opposing direction.
The electricity storage cell according to claim 1 or 2. When viewed from the opposing direction, the sealing section is formed in a rectangular frame shape, and the tape is provided on at least one side of the sealing section.
The electricity storage cell according to any one of claims 1 to 3. Equipped with a laminate in which multiple storage cells are stacked,
At least one of the plurality of storage cells is the storage cell according to any one of claims 1 to 4,
Power storage device.

Images