Power storage cell and method for manufacturing electrode mixture layer

Abstract

To provide a power storage cell which can have an improved liquid storage property.SOLUTION: A power storage cell 1 using an electrolyte includes: a first electrode mixture material layer 32; a separator 50; and a second electrode mixture material layer 42 facing the first electrode mixture material layer 32 with the separator 50 in between. The first electrode mixture material layer 32 includes a first general part 33 and a first high-density part 34 more dense than the first general part 33. The high-density part 34 is provided to surround the first general part 33 while dividing the first general part 33 into at least two regions.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a storage battery cell.

Background Art

[0002] As a conventional storage battery cell, Japanese Patent Application Laid-Open No. 2016-100278 (Patent Document 1) discloses a technique for suppressing an increase in internal resistance by making the transmission coefficient of the outer edge portions of the first electrode and the second electrode smaller than the transmission coefficient of the central portions of the first electrode and the second electrode.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] During charging and discharging, the expansion and contraction of the composite material layer cause the electrolyte to be extruded from the central portions of the first electrode and the second electrode to the outside of the first electrode and the second electrode. When the areas of the first electrode and the second electrode become large, the distance for the electrolyte extruded to the outside to return to the central portion of the composite material layer becomes long. As a result, it is feared that the electrolyte extruded to the outside becomes difficult to return to the central portion of the composite material layer, and the amount of retained liquid in the central portion decreases.

[0005] The present disclosure has been made in view of the above problems, and an object of the present disclosure is to provide a storage battery cell capable of enhancing liquid retention and a method for manufacturing an electrode composite material layer.

Means for Solving the Problems

[0006] The energy storage cell based on the present disclosure is a cell in which an electrolytic solution is used. The energy storage cell includes a first electrode composite layer, a separator, and a second electrode composite layer facing the first electrode composite layer with the separator interposed therebetween. The first electrode composite layer includes a first general portion and a first high-density portion having a higher density than the first general portion. The first high-density portion is provided so as to surround the first general portion while dividing the first general portion into two or more regions.

[0007] According to the above configuration, while the first general portion of the first electrode composite layer is divided into two or more regions, the first high-density portion surrounds the first general portion, so that the electrolytic solution can be prevented from being extruded from each region of the divided first general portion to the outside of the first electrode composite layer.

[0008] Further, as compared with a configuration in which the outer edge of a single first general portion is surrounded by a first high-density portion, the distance from the first high-density portion surrounding each region of the divided first general portion to the center of each region of the divided first general portion can be shortened. Therefore, even when the area of the first electrode composite layer becomes large, the electrolytic solution extruded to the outside of the first electrode composite layer can easily return to the center of each region of the divided first general portion, and the liquid retention property can be enhanced.

[0009] In the energy storage cell based on the present disclosure, the second electrode composite layer may include a second general portion and a second high-density portion having a higher density than the second general portion. The second high-density portion may be provided so as to surround the second general portion. The first general portion surrounded by the first high-density portion may be arranged so as to face at least a part of the second general portion surrounded by the second high-density portion with the separator interposed therebetween.

[0010] According to the above configuration, since the first electrode composite layer includes the first high-density portion and the second electrode composite layer also includes the second high-density portion, it is possible to suppress the electrolytic solution from being extruded to the outside of the second electrode composite layer also on the second electrode composite layer side.

[0011] In the storage cell according to the present disclosure, the second high-density portion may be provided so as to surround the second general portion while dividing the second general portion into two or more regions. In this case, when viewed from the lamination direction in which the first electrode composite layer and the second electrode composite layer are laminated, the region of the first general portion surrounded by the first high-density portion and the region of the second general portion surrounded by the second high-density portion may coincide.

[0012] According to the above configuration, while enhancing the liquid retention property in the first electrode composite layer and the second electrode composite layer, the capacity retention effect (dischargeable SOC) can be enhanced.

[0013] In the storage cell according to the present disclosure, the density of the first high-density portion may be 10% or more higher than that of the first general portion.

[0014] According to the above configuration, the capacity retention effect can be enhanced.

[0015] In the storage cell according to the present disclosure, when the ratio of the area of the first general portion surrounded by the first high-density portion to the area of the first electrode composite layer is B (%) and the average discharge rate during discharge is C, the relationship 9 ≦ B × C < 199 may be satisfied.

[0016] According to the above configuration, the capacity retention effect can be enhanced.

[0017] In the storage cell according to the present disclosure, the relationship between B and C may satisfy 17 ≦ B × C < 99.

[0018] According to the above configuration, the capacity retention effect can be further enhanced.

[0019] In the storage cell according to the present disclosure, the thickness of the first high-density portion may be thicker than the thickness of the first general portion.

[0020] According to the above configuration, as the first high-density portion becomes thicker, its function as a wall is enhanced, and it becomes difficult for the electrolytic solution to be discharged to the outside of the first electrode mixture layer.

[0021] In the storage battery cell based on the present disclosure, the area of each of the first general portions divided by the first high-density portion may be 600 cm 2 or more.

[0022] Generally, when the area of the electrode mixture layer increases, liquid depletion is likely to occur. According to the above configuration, even if the area of the first general portion is equal to or greater than the above value, since the above-described first high-density portion is provided, the liquid retention property is enhanced and liquid depletion is less likely to occur. Thereby, a decrease in capacity can be suppressed.

[0023] The method for manufacturing an electrode mixture layer based on the present disclosure includes a step of disposing a frame member on a current collector and applying an electrode slurry inside the frame member, a step of forming a general film thickness portion and a thick film portion having a thickness greater than that of the general film thickness portion on the applied electrode slurry, and a step of pressing the electrode slurry on which the thick film portion is formed. In the step of forming the thick film portion, while dividing the general film thickness portion into two or more regions, the thick film portion is formed so as to surround the general film thickness portion. In the pressing step, a general portion is formed in a portion where the general film thickness portion is formed, and a high-density portion having a density higher than that of the general portion is formed in a portion where the thick film portion is formed.

[0024] According to the above configuration, it is possible to manufacture an electrode mixture layer in which the general portion is divided into two or more regions and the high-density portion surrounds the general portion. By using the electrode mixture layer, it is possible to enhance the liquid retention property as described above.

Effect of the Invention

[0025] According to the present disclosure, it is possible to provide a storage battery cell and a method for manufacturing an electrode mixture layer capable of enhancing the liquid retention property.

Brief Description of the Drawings

[0026]

Figure 1

Figure 2

Figure 3

Figure 4

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Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

MODE FOR CARRYING OUT THE INVENTION

[0027] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the embodiments shown below, the same or common parts are denoted by the same reference numerals in the drawings, and the description thereof will not be repeated.

[0028] (Embodiment 1) FIG. 1 is a schematic plan view of a power storage cell according to Embodiment 1. FIG. 2 is a schematic cross-sectional view taken along line II-II shown in FIG. 1. With reference to FIGS. 1 and 2, the power storage cell 1 according to Embodiment 1 will be described.

[0029] The power storage cell 1 according to the form of Embodiment 1 is for vehicle drive, and is mounted on, for example, a hybrid vehicle having an internal combustion engine such as a gasoline engine or a diesel engine and a motor supplied with power from a rechargeable battery, a plug-in hybrid vehicle capable of external charging, an electric vehicle, and the like.

[0030] In Embodiment 1, the case where the power storage cell 1 is a laminated liquid-based battery will be exemplified and described, but it is not limited to the laminated type, and may be a rectangular prism-shaped liquid-based battery. That is, the exterior body 20 described later may be constituted by a rectangular prism-shaped metal member.

[0031] As shown in FIGS. 1 and 2, the power storage cell 1 according to Embodiment 1 includes an electrode body 10, an exterior body 20, a first electrode terminal 25P, and a second electrode terminal 25N. For example, the first electrode terminal 25P is a positive electrode terminal, and the second electrode terminal 25N is a negative electrode terminal.

[0032] The exterior body 20 houses the electrode body 10 and the electrolytic solution. The exterior body 20 is constituted by, for example, lamination. The electrolytic solution contains, for example, a non-aqueous solvent and a supporting salt such as a lithium salt that generates a charge carrier.

[0033] The electrode body 10 is a so-called laminated electrode body, and includes a plurality of first electrodes 30, a plurality of second electrodes 40, and a plurality of separators 50. For example, the first electrode 30 is a positive electrode, and the second electrode 40 is a negative electrode. The electrode body 10 is constituted by laminating the first electrode 30 and the second electrode 40 with the separator 50 interposed therebetween. Note that the first electrode 30 and the second electrode 40 may each have one or more sheets.

[0034] Each first electrode 30 includes a first electrode current collector 31 and a first electrode composite layer 32. The first electrode current collector 31 is provided in a sheet shape. The first electrode current collector 31 is a positive electrode current collector. The first electrode current collector 31 has a rectangular main body portion and the above-described first electrode tab 35 protruding from one side of the main body portion.

[0035] When viewed in the stacking direction of the first electrode 30 and the second electrode 40, each first electrode tab 35 is arranged so as to overlap with each other. Each first electrode tab 35 is connected to the first electrode terminal 25P.

[0036] The first electrode current collector 31 is formed of, for example, an aluminum foil or an aluminum alloy foil. The first electrode composite layer 32 is provided on the surface of the first electrode current collector 31. More specifically, the first electrode composite layer 32 is provided on each of both surfaces of the first electrode current collector 31 in the stacking direction. Note that the first electrode tab 35 is not provided with the first electrode composite layer 32. The first electrode composite layer 32 is a positive electrode composite layer.

[0037] The first electrode composite layer 32 includes a first general portion 33 and a first high-density portion 34 having a higher density than the first general portion 33. The first high-density portion 34 has a density that is, for example, 10% or more higher than that of the first general portion 33. The thickness of the first high-density portion 34 may be the same as that of the first general portion 33 or may be thicker than the first general portion 33.

[0038] The coated area of the first electrode composite layer 32 is, for example, about 7000 cm 2 but is not limited thereto. The coated area of the first electrode composite layer 32 is 600 cm 2 or more, 1000 cm 2 or more, 3000 cm 2 or more, 4000 cm 2 or more, 5000 cm 2 or more, 6000 cm 2 or more, 7000 cm 2 or more, 8000 cm 2 or more, 10000 cm 2 or more. Also, the coated area of the first electrode composite layer 32 is 7000 cm2 Hereinafter, 8000 cm 2 Hereinafter, 10000 cm 2 Hereinafter, 12000 cm 2 It may be the following. The coated area of the first electrode composite material layer 32 is 6500 cm 2 Above 7500 cm 2 It may be the following. Even if the coated area of the first electrode composite material layer 32 increases, the electrolytic solution extruded outside the first electrode composite material layer 32 can easily return to the center of each region of the divided first general part 33, and the liquid retention property can be enhanced. Also, the basis weight of the first electrode composite material layer 32 is, for example, about 30 mg / cm 2 However, it is not limited thereto. The basis weight of the first electrode composite material layer 32 is 20 mg / cm 2 Above, 30 mg / cm 2 Above, 40 mg / cm 2 Above, 50 mg / cm 2 Above, 60 mg / cm 2 It may be above. The basis weight of the first electrode composite material layer 32 is 30 mg / cm 2 Below, 40 mg / cm 2 Below, 50 mg / cm 2 It may be below.

[0039] The first electrode composite material layer 32 has a first electrode active material. The first electrode active material is, for example, a material capable of occluding and releasing lithium. As the first electrode active material, for example, lithium cobalt oxide (LiCoO2), lithium manganate (LiMn2O4), lithium nickel oxide (LiNiO2), etc. can be used. Also, as the first electrode active material, a lithium transition metal composite oxide such as lithium nickel cobalt manganese composite oxide may be adopted.

[0040] Each second electrode 40 includes a second electrode current collector 41 and a second electrode composite material layer 42. The second electrode current collector 41 is provided in a sheet shape. The second electrode current collector 41 has a rectangular main body portion and the second electrode tab 45 protruding from one side of the main body portion.

[0041] When viewed in the stacking direction of the first electrode 30 and the second electrode 40, the second electrode tabs 45 are arranged so as to overlap each other. Each second electrode tab 45 is connected to the second electrode terminal 25N.

[0042] The second electrode current collector 41 is formed of, for example, a copper foil. A second electrode composite layer 42 is provided on the surface of the second electrode current collector 41. More specifically, the second electrode composite layer 42 is provided on each of both surfaces of the second electrode current collector 41 in the stacking direction. Note that the second electrode tab 45 described above is not provided with the second electrode composite layer 42. The second electrode composite layer 42 is a negative electrode composite layer.

[0043] The second electrode composite layer 42 faces the first electrode composite layer 32 with the separator 50 interposed therebetween. The second electrode composite layer 42 includes a second general portion 43 and a second high-density portion 44 having a higher density than the second general portion 43. The second high-density portion 44 has a density that is, for example, 10% or more higher than that of the second general portion 43. The thickness of the second high-density portion 44 may be equal to that of the second general portion 43 or may be thicker than the second general portion 43.

[0044] The coating area of the second electrode composite layer 42 is larger than the coating area of the first electrode composite layer 32. The coating area of the second electrode composite layer 42 is, for example, about 7050 cm 2 but is not limited thereto. The coating area of the second electrode composite layer 42 is 600 cm 2 or more, 1000 cm 2 or more, 3000 cm 2 or more, 4000 cm 2 or more, 5000 cm 2 or more, 6000 cm 2 or more, 7000 cm 2 or more, 8000 cm 2 or more, 10000 cm 2 or more, 12000 cm 2 or more may be sufficient. The coating area of the second electrode composite layer 42 is 7000 cm 2 or less, 8000 cm 2 or less, 10000 cm 2 or less, 12000 cm 2The following may be applicable. The coating area of the second electrode composite material layer 42 may be 6500 cm 2 or more and 7500 cm 2 or less. Even if the coating area of the second electrode composite material layer 42 increases, the electrolytic solution extruded outside the first electrode composite material layer 32 is likely to return to the center of each region of the divided first general part 33, and the liquid retention property can be enhanced. Also, the basis weight of the second electrode composite material layer 42 is, for example, about 20 mg / cm 2 , but is not limited thereto. The basis weight of the second electrode composite material layer 42 may be 20 mg / cm 2 or more, 30 mg / cm 2 or more, 40 mg / cm 2 or more, 50 mg / cm 2 or more. The basis weight of the first electrode composite material layer 32 may be 30 mg / cm 2 or less, 40 mg / cm 2 or less, 50 mg / cm 2 or less.

[0045] The second electrode composite material layer 42 has a second electrode active material. The second electrode active material is, for example, a material capable of occluding and releasing lithium ions. As the second electrode active material, for example, a carbon material such as graphite can be adopted.

[0046] The separator 50 is interposed between the first electrode 30 and the second electrode 40. The separator 50 insulates the first electrode composite material layer 32 and the second electrode composite material layer 42. As the separator 50, a resin sheet such as polyethylene (PE) or polypropylene (PP) can be adopted.

[0047] The first electrode terminal 25P has one end and the other end in a direction orthogonal to the stacking direction. One end side of the first electrode terminal 25P is exposed from the exterior body 20. The other end side of the first electrode terminal 25P is located inside the exterior body 20.

[0048] The other end side of the first electrode terminal 25P is joined to the first electrode tab 35. This joining may be performed by resistance welding, or may be performed by laser welding, ultrasonic welding, or the like. The first electrode terminal 25P is composed of a plate-shaped metal member. Specifically, the first electrode terminal 25P is composed of an aluminum plate.

[0049] The second electrode terminal 25N has one end and the other end in a direction orthogonal to the stacking direction. One end side of the second electrode terminal 25N is exposed from the exterior body 20. The other end side of the second electrode terminal 25N is located inside the exterior body 20.

[0050] The other end side of the second electrode terminal 25N is joined to the second electrode tab 45 by welding or the like. This joining may be performed by resistance welding, or may be performed by laser welding, ultrasonic welding, or the like. The second electrode terminal 25N is composed of a plate-shaped metal member. Specifically, the second electrode terminal 25N is composed of a copper plate.

[0051] FIG. 3 is a schematic plan view of the second electrode of the storage cell according to Embodiment 1. With reference to FIG. 3, the details of the second electrode 40 will be described.

[0052] As shown in FIG. 3, the second high-density portion 44 of the second electrode 40 is provided so as to surround the second general portion 43 while dividing the second general portion 43 into two regions. The second high-density portion 44 includes a frame-shaped portion 441 and a partition portion 442.

[0053] The frame-shaped portion 441 includes a first portion along three sides of the main body portion of the second electrode current collector 41 and a second portion provided inside the remaining one side of the main body portion along the remaining one side. The first portion has an angular U-shape, and the second portion is provided linearly. The second portion is located away from the remaining one side of the main body portion. The distance from the remaining one side of the main body portion to the second portion is longer than the distance from each of the three sides of the main body portion to the first portion. The distance from the remaining one side of the main body portion to the second portion is substantially the same as the width of the first high-density portion 34 described later. No second electrode composite layer 42 is provided between the second portion and the remaining one side.

[0054] The partition portion 442 is provided so as to divide the region surrounded by the frame-shaped portion 441 into two parts. A second general portion 43 is provided in each of the regions divided by the partition portion 442. The partition portion 442 is provided linearly. The partition portion 442 is provided substantially parallel to the second portion.

[0055] FIG. 4 is a schematic plan view of the first electrode of the storage cell according to Embodiment 1. With reference to FIG. 4, the details of the first electrode 30 will be described.

[0056] As shown in FIG. 4, the first high-density portion 34 of the first electrode 30 is provided so as to surround the first general portion 33 while dividing the first general portion 33 into two regions. The first high-density portion 34 includes a frame-shaped portion 341 and a partition portion 342.

[0057] The frame-shaped portion 341 is provided along the four sides of the main body portion of the first electrode current collector 31. The frame-shaped portion 341 may be spaced apart from the four sides of the main body portion. The partition portion 342 is provided so as to divide the region surrounded by the frame-shaped portion 341 into two parts. A first general portion 33 is provided in each of the regions divided by the partition portion 342. The partition portion 342 is provided linearly.

[0058] FIG. 5 is a schematic plan view showing the positional relationship between the second electrode and the first electrode of the storage cell according to Embodiment 1. As shown in FIG. 5, when viewed from the stacking direction, the first high-density portion 34 is arranged so as to be adjacent to the second high-density portion 44.

[0059] Specifically, when viewed from the stacking direction, the frame-shaped portion 341 is adjacent to the frame-shaped portion 441. More specifically, the frame-shaped portion 341 includes a portion adjacent to and inside the first portion of the frame-shaped portion 441 and a portion adjacent to and outside the second portion of the frame-shaped portion 441. When viewed from the stacking direction, the partition portion 342 is adjacent to the partition portion 442.

[0060] The first general portion 33 surrounded by the first high-density portion 34 is arranged so as to face at least a part of the second general portion 43 surrounded by the second high-density portion 44 with the separator 50 interposed therebetween.

[0061] In the first general portion 33 located on one side in the arrangement direction in which the first general portions 33 are arranged, a part on one side in the arrangement direction faces the second general portion 43 with the separator 50 interposed therebetween. The part on the other side in the arrangement direction faces the partition portion 442 with the separator 50 interposed therebetween.

[0062] In the first general portion 33 located on the other side in the arrangement direction, a part on one side in the arrangement direction faces the second general portion 43 with the separator 50 interposed therebetween. The part on the other side in the arrangement direction faces the second portion of the frame-shaped portion 441 with the separator 50 interposed therebetween.

[0063] FIGS. 6 to 9 are schematic views showing the first to fourth steps in manufacturing the second electrode composite layer according to Embodiment 1. In FIGS. 6 to 9, for convenience, the second electrode current collector 41 is omitted. The manufacturing method of the second electrode composite layer 42 will be described with reference to FIGS. 6 to 9. Since the first electrode composite layer 32 is manufactured in substantially the same manner, the manufacturing method of the first electrode composite layer 32 will be omitted here.

[0064] When manufacturing the second electrode composite material layer 42, as shown in FIG. 6, first, a frame member 70 is disposed on the surface of the second electrode current collector 41, and the second electrode slurry 48 is applied inside the frame member using a coating device. The applied second electrode slurry 48 is spread with a first squeegee 71. In the first squeegee 71, the portion that contacts the second electrode slurry 48 is flat. By setting the viscosity of the second electrode slurry 48 to about 10,000 mPa·s, the outer edge portion of the second electrode slurry 48 that contacts the frame member 70 becomes thicker than the central portion due to surface tension.

[0065] Subsequently, as shown in FIG. 7, the surface shape of the second electrode slurry 48 is adjusted using a second squeegee 75. In the second squeegee 75, a notch 76 is provided in the portion that contacts the second electrode slurry 48. The notch 76 is provided so as to face in the direction (upward) away from the second electrode slurry 48. The notch 76 is provided at a position corresponding to the partition portion 442 of the second high-density portion 44. By sliding the second squeegee 75 on the surface of the second electrode slurry 48, a protrusion 49 is formed on the line through which the notch 76 passes. The portion where the protrusion 49 is formed becomes a thick film. In this way, while dividing the general film thickness portion into two or more regions, a thick film portion is formed so as to surround the general film thickness portion. The thick film portion is thicker than the general film thickness portion.

[0066] Subsequently, the second electrode slurry 48 with the adjusted surface shape is pressed. For example, the second electrode current collector 41 and the second electrode slurry 48 are sandwiched by a pressing device such as a pressure roller. As a result, as shown in FIG. 8, the second electrode composite material layer 42 is formed. More specifically, the thick film portion provided at the outer edge portion of the second electrode slurry 48 and the thick film portion at the location where the protrusion 49 is formed become the second high-density portion 44, and the other portion (the above-mentioned general film thickness portion) of the second electrode slurry 48 becomes the second general portion 43. In this state, the second high-density portion 44 is thicker than the second general portion 43.

[0067] Subsequently, the second electrode composite layer 42 with the second high-density portion 44 formed thereon is pressed again. Similar to the above, the second electrode current collector 41 and the second electrode composite layer 42 are sandwiched by a pressing device such as a pressure roller. As a result, as shown in FIG. 9, the thicknesses of the second high-density portion 44 and the second general portion 43 become substantially equal. Note that the thickness of the second high-density portion 44 may be greater than that of the second general portion 43. For example, the thickness of the second high-density portion 44 may be 1% or more greater than that of the second general portion 43, or may be 2% or more greater. Furthermore, the thickness of the second high-density portion 44 may be 3% or more greater than that of the second general portion 43. The formed second high-density portion 44 may have a density 10% or more higher than that of the second general portion 43, for example.

[0068] Similar to the above, the first electrode composite layer 32 can also be formed by applying the first electrode slurry onto the first electrode current collector 31, adjusting the shape using the first squeegee and the second squeegee, and then pressing twice.

[0069] In the first electrode composite layer 32, the thickness of the first high-density portion 34 may be greater than that of the first general portion 33. For example, the thickness of the first high-density portion 34 may be 1% or more greater than that of the first general portion 33, or may be 2% or more greater. Furthermore, the thickness of the first high-density portion 34 may be 3% or more greater than that of the first general portion 33. The formed first high-density portion 34 may have a density 10% or more higher than that of the first general portion 33, for example.

[0070] As described above, in the storage cell 1 according to Embodiment 1, the first high-density portion 34 is provided so as to surround the first general portion 33 while dividing the first general portion 33 into two or more regions. Thereby, it is possible to suppress the electrolytic solution from being extruded outside the first electrode composite layer 32 from each region of the divided first general portion 33.

[0071] Further, compared with the configuration in which the outer edge of a single first general portion is surrounded by a first high-density portion, the distance from each first high-density portion 34 surrounding each region of the divided first general portion 33 to the center portion of each of the divided first general portions 33 can be shortened. For this reason, even when the area of the first electrode composite material layer 32 becomes large, the electrolytic solution extruded outside the first electrode composite material layer 32 easily returns to the center portion of each region of the divided first general portion 33, and the liquid retention property can be enhanced.

[0072] Furthermore, in the second electrode composite material layer 42, the second high-density portion 44 is provided so as to surround the second general portion 43, and the first general portion 33 surrounded by the first high-density portion 34 is arranged to face at least a part of the second general portion 43 surrounded by the second high-density portion 44 with the separator 50 interposed therebetween. Thereby, also on the second electrode composite material layer 42 side, it is possible to suppress the electrolytic solution from being extruded outside the second electrode composite material layer 42.

[0073] Also, since the thickness of the first high-density portion 34 is greater than the thickness of the first general portion 33, it becomes difficult for the electrolytic solution to be discharged outside the first electrode composite material layer 32. Similarly, since the thickness of the second high-density portion 44 is greater than the thickness of the second general portion 43, it becomes difficult for the electrolytic solution to be discharged outside the second electrode composite material layer 42.

[0074] (Embodiment 2) FIG. 10 is a schematic plan view showing the positional relationship between the second electrode and the first electrode of the power storage cell according to Embodiment 2. With reference to FIG. 10, the power storage cell according to Embodiment 2 will be described.

[0075] As shown in FIG. 10, the configuration of the electrode body 10A of the power storage cell according to Embodiment 2 is different from that of the power storage cell 1 according to Embodiment 1. Regarding other configurations, they are substantially the same.

[0076] The electrode body 10A is different in the arrangement of the first general portion 33 and the first high-density portion 34, and the arrangement of the second general portion 43 and the second high-density portion 44, compared with the electrode body 10 according to Embodiment 1.

[0077] In this embodiment, the frame portion 441 of the second high-density portion 44 is provided in a frame shape along the outer edge of the second electrode current collector 41, and the partition portion 442 is provided so as to divide the region surrounded by the frame portion 441 into two substantially equal parts. The second general portion 43 is disposed in the two divided regions. The first general portion 33 and the first high-density portion 34 have substantially the same shape as the second general portion 43 and the second high-density portion 44.

[0078] When viewed from the stacking direction, the region of the first general portion 33 surrounded by the first high-density portion 34 coincides with the region of the second general portion 43 surrounded by the second high-density portion 44. Also, the region of the first general portion 33 surrounded by the first high-density portion 34 does not overlap with the frame portion 441, and the region of the second general portion 43 surrounded by the second high-density portion 44 does not overlap with the frame portion 341 either. Further, when viewed from the stacking direction, the frame portion 341 is disposed so as to overlap with the frame portion 441, and the partition portion of the first high-density portion 34 is disposed so as to overlap with the partition portion 442 of the second high-density portion 44.

[0079] Even in such a configuration, the storage battery cell according to Embodiment 2 can obtain substantially the same effects as the storage battery cell according to Embodiment 1. Also, when viewed from the stacking direction, by the regions of the first general portion 33 and the second general portion 43 overlapping, it is possible to enhance the liquid retention property in the first electrode composite layer 32 and the second electrode composite layer 42 while enhancing the capacity retention effect (capacity retention rate).

[0080] (Embodiment 3) FIG. 11 is a schematic plan view showing the positional relationship between the second electrode and the first electrode of the storage battery cell according to Embodiment 3. With reference to FIG. 11, the storage battery cell according to Embodiment 3 will be described.

[0081] As shown in FIG. 11, the configuration of the electrode body 10B of the storage battery cell according to Embodiment 3 is different from that of the storage battery cell 1 according to Embodiment 1. Regarding other configurations, they are substantially the same.

[0082] The electrode body 10B has different arrangements of the first general part 33, the first high-density part 34, the second general part 43, and the second high-density part 44 compared to the electrode body 10 according to the first embodiment.

[0083] In the present embodiment, the frame-shaped part 441 of the second high-density part 44 is provided in a frame shape along the outer edge of the second electrode current collector 41, and the partition part 442 is provided so as to divide the region surrounded by the frame-shaped part 441 into two parts. The areas of the two divided regions may be different from each other.

[0084] When viewed from the stacking direction, the frame-shaped part 341 of the first high-density part 34 is arranged so as not to overlap the frame-shaped part 441 of the second high-density part 44, and is arranged inside the frame-shaped part 441 at a predetermined distance from the frame-shaped part 441. When viewed from the stacking direction, the partition part 342 is arranged so as not to overlap the partition part 442, and is arranged at a predetermined distance from the partition part 442.

[0085] Even in such a configuration, the storage cell according to the second embodiment can obtain substantially the same effects as the storage cell according to the first embodiment.

[0086] (Embodiment 4) FIG. 12 is a schematic plan view showing the positional relationship between the second electrode and the first electrode of the storage cell according to the fourth embodiment. With reference to FIG. 12, the storage cell according to the fourth embodiment will be described.

[0087] As shown in FIG. 12, the storage cell according to the fourth embodiment has a different configuration of the electrode body 10C compared to the storage cell 1 according to the first embodiment. For other configurations, they are substantially the same.

[0088] The electrode body 10C has different arrangements of the first general part 33, the first high-density part 34, the second general part 43, and the second high-density part 44 compared to the electrode body 10 according to the first embodiment.

[0089] In the present embodiment, the frame portion 441 of the second high-density portion 44 is provided in a frame shape along the outer edge of the second electrode current collector 41, and the partition portion 442 is provided so as to divide the region surrounded by the frame portion 441 into two substantially equal parts. The second general portion 43 is disposed in the two divided regions.

[0090] The first high-density portion 34 includes two frame portions. When viewed from the stacking direction, the two frame portions are respectively disposed in the regions within the frame portion 441 divided into two by the partition portion 442. The first general portion 33 is disposed inside each of the two frame portions. When viewed from the stacking direction, the first general portion 33 is arranged so as not to overlap with the second high-density portion 44, inside the second general portion 43, and to overlap a part of the second general portion 43.

[0091] Even in such a configuration, the storage cell according to Embodiment 2 can obtain substantially the same effects as the storage cell according to Embodiment 1.

[0092] (Other Modification Examples) In the above-described Embodiments 1 to 4, the case where the first electrode is the positive electrode, the second electrode is the negative electrode, the first electrode composite layer 32 is the positive electrode composite layer, and the second electrode composite layer 42 is the negative electrode composite layer has been exemplified and described, but it is not limited thereto. That is, the first electrode may be the negative electrode, the second electrode may be the positive electrode, the first electrode composite layer 32 may be the negative electrode composite layer, and the second electrode composite layer 42 may be the positive electrode composite layer.

[0093] In the above-described Embodiments 1 to 4, the case where each of the first general portion 33 and the second general portion 43 is divided into two has been exemplified and described, but it is not limited thereto, and at least one of the first general portion 33 and the second general portion 43 may be divided into two or more. Both the first general portion 33 and the second general portion 43 may be divided into two or more. The number of divisions of the first general portion 33 and the number of divisions of the second general portion 43 may be the same or different.

[0094] (First Verification Experiment) FIG. 13 is a diagram showing the conditions and results of the first verification experiment. With reference to FIG. 13, the first verification experiment will be described.

[0095] As shown in FIG. 13, in the first verification experiment, power storage cells according to Comparative Example 1, Reference Example 1, and Examples 1 to 6 were prepared, and the performance of each power storage cell was evaluated. Specifically, at an environmental temperature of 25° C., SOC from 0% to 100% was carried out for 300 cycles at a current value of 0.2C, charged at 1C for 5 cycles between SOC 0% and 100%, and then set to SOC 100%, and the dischargeable SOC when discharging to a lower limit voltage of 3V was evaluated. Note that the current value during discharge was evaluated at 1C and 2C, respectively.

[0096] Note that the capacity of each power storage cell was 60 Ah. Also, in each power storage cell, the coating area of the first electrode composite layer (positive electrode composite layer) was 7000 cm 2 and the first electrode (positive electrode) basis weight was 30 mg / cm 2 The coating area of the second electrode composite layer (negative electrode composite layer) was 7050 cm 2 and the second electrode (negative electrode) basis weight was 20 mg / cm 2 was used.

[0097] As the power storage cell according to Comparative Example 1, as shown in FIG. 13, the number of electrode divisions was 0. Specifically, the first electrode composite layer 32 was composed only of the first general portion 33, and a power storage cell in which the first high-density portion 34 was not provided was prepared. Similarly, the second electrode composite layer 42 was also composed only of the second general portion 43, and the second high-density portion 44 was not provided. That is, the area A of the general portion surrounded by the high-density portion was 0 cm 2 and the ratio B of the area A of the general portion to the area of the electrode composite layer was 0%.

[0098] In the storage cell according to Comparative Example 1, the liquid retention amount of the negative electrode after 300 cycles was 88%. Also, when discharging with the average current value C as 1C (1C discharge), B×C was 0, and the discharge time was 30 minutes. The dischargeable SOC was 50.0%. When discharging with the average current value C as 2C (2C discharge), B×C was 0, and the discharge time was 3 minutes. The dischargeable SOC was 10.0%.

[0099] As the storage cell according to Reference Example 1, the number of electrode divisions was 1. Specifically, in the first electrode composite layer 32, the outer periphery of the first general portion 33 was surrounded by the first high-density portion 34, and the number of the first general portions 33 was 1. At this time, the area A of the first general portion 33 surrounded by the first high-density portion 34 was 6952 cm 2 and the ratio B of the area A of the first general portion 33 to the area of the first electrode composite layer 32 was 99%. Also, on the side of the second electrode composite layer 42, the configuration was substantially the same as that of the first electrode composite layer 32. That is, the number of divisions of the second general portion 43 was 1.

[0100] In the storage cell according to Reference Example 1, the liquid retention amount of the negative electrode after 300 cycles was 91%. Also, when discharging with the average current value C as 1C (1C discharge), B×C was 99, and the discharge time was 42 minutes. The dischargeable SOC was 70.0%. When discharging with the average current value C as 2C (2C discharge), B×C was 199, and the discharge time was 4 minutes. The dischargeable SOC was 13.3%.

[0101] As the storage cell according to Example 1, the number of electrode divisions was 2. Specifically, the storage cell according to Embodiment 2 was prepared. At this time, the area A of each first general portion 33 surrounded by the first high-density portion 34 was 3404 cm 2 and the ratio B of the area A of each first general portion 33 to the area of the first electrode composite layer 32 was 49%. Also, on the side of the second electrode composite layer 42, the configuration was substantially the same as that of the first electrode composite layer 32. That is, the number of divisions of the second general portion 43 was 2.

[0102] In the storage battery cell according to Example 1, the liquid retention amount of the negative electrode after 300 cycles was 97%. Also, when discharging with the average current value C being 1C (1C discharge), B×C was 49, and the discharge time was 48 minutes. The dischargeable SOC was 80.0%. When discharging with the average current value C being 2C (2C discharge), B×C was 97, and the discharge time was 21 minutes. The dischargeable SOC was 70.0%.

[0103] As the storage battery cell according to Example 2, the number of electrode divisions was 3. Specifically, the inside of the frame portion 341 of the first high-density portion 34 was divided into three by two partition portions 342, and the first general portion 33 was disposed in each of the three divided regions. At this time, the area A of each first general portion 33 surrounded by the first high-density portion 34 was 2189 cm 2 And the ratio B of the area A of each first general portion 33 to the area of the first electrode composite layer 32 was 31%. Also, on the side of the second electrode composite layer 42, the configuration was substantially the same as that of the first electrode composite layer 32. That is, the number of divisions of the second general portion 43 was 3.

[0104] In the storage battery cell according to Example 2, the liquid retention amount of the negative electrode after 300 cycles was 99%. Also, when discharging with the average current value C being 1C (1C discharge), B×C was 31, and the discharge time was 50 minutes. The dischargeable SOC was 83.3%. When discharging with the average current value C being 2C (2C discharge), B×C was 63, and the discharge time was 23 minutes. The dischargeable SOC was 76.7%.

[0105] As the storage battery cell according to Example 3, the number of electrode divisions was 4. Specifically, the inside of the frame portion 341 of the first high-density portion 34 was divided into four by a plurality of partition portions 342, and the first general portion 33 was disposed in each of the four divided regions. At this time, the area A of each first general portion 33 surrounded by the first high-density portion 34 was 1558 cm 2 And the ratio B of the area A of each first general portion 33 to the area of the first electrode composite layer 32 was 22%. Also, on the side of the second electrode composite layer 42, the configuration was substantially the same as that of the first electrode composite layer 32. That is, the number of divisions of the second general portion 43 was 4.

[0106] In the storage battery cell according to Example 3, the liquid retention amount of the negative electrode after 300 cycles was 99%. Further, when discharging with the average current value C being 1C (1C discharge), B×C was 22, and the discharge time was 51 minutes. The dischargeable SOC was 85.0%. When discharging with the average current value C being 2C (2C discharge), B×C was 45, and the discharge time was 24 minutes. The dischargeable SOC was 80.0%.

[0107] As the storage battery cell according to Example 4, the number of electrode divisions was 5. Specifically, the inside of the frame-shaped portion 341 of the first high-density portion 34 was divided into 5 by a plurality of partition portions 342, and the first general portion 33 was disposed in each of the 5 divided regions. At this time, the area A of each first general portion 33 surrounded by the first high-density portion 34 was 1160 cm 2 and the ratio B of the area A of each first general portion 33 to the area of the first electrode composite layer 32 was 17%. Also, on the side of the second electrode composite layer 42, the configuration was substantially the same as that of the first electrode composite layer 32. That is, the number of divisions of the second general portion 43 was 5.

[0108] In the storage battery cell according to Example 4, the liquid retention amount of the negative electrode after 300 cycles was 99%. Further, when discharging with the average current value C being 1C (1C discharge), B×C was 17, and the discharge time was 52 minutes. The dischargeable SOC was 86.7%. When discharging with the average current value C being 2C (2C discharge), B×C was 33, and the discharge time was 24 minutes. The dischargeable SOC was 80.0%.

[0109] As the storage battery cell according to Example 5, the number of electrode divisions was 6. Specifically, the inside of the frame-shaped portion 341 of the first high-density portion 34 was divided into 6 by a plurality of partition portions 342, and the first general portion 33 was disposed in each of the 6 divided regions. At this time, the area A of each first general portion 33 surrounded by the first high-density portion 34 was 879 cm 2The area A of each first general part 33 was set to 13% of the area of the first electrode composite layer 32. Also, on the second electrode composite layer 42 side, the configuration was made substantially the same as that of the first electrode composite layer 32. That is, the number of divisions of the second general part 43 was set to 6.

[0110] In the storage cell according to Example 5, the liquid retention amount of the negative electrode after 300 cycles was 94%. Also, when discharging with the average current value C set to 1C (1C discharge), B×C was 13, the discharge time was 40 minutes, and the dischargeable SOC was 66.7%. When discharging with the average current value C set to 2C (2C discharge), B×C was 25, the discharge time was 18 minutes, and the dischargeable SOC was 60.0%.

[0111] As the storage cell according to Example 6, the number of electrode divisions was set to 7. Specifically, the inside of the frame-shaped part 341 of the first high-density part 34 was divided into 7 by a plurality of partition parts 342, and the first general part 33 was arranged in each of the 7 divided regions. At this time, the area A of each first general part 33 surrounded by the first high-density part 34 was 664 cm 2 and the ratio B of the area A of each first general part 33 to the area of the first electrode composite layer 32 was set to 9%. Also, on the second electrode composite layer 42 side, the configuration was made substantially the same as that of the first electrode composite layer 32. That is, the number of divisions of the second general part 43 was set to 7.

[0112] In the storage cell according to Example 5, the liquid retention amount of the negative electrode after 300 cycles was 92%. Also, when discharging with the average current value C set to 1C (1C discharge), B×C was 9, the discharge time was 35 minutes, and the dischargeable SOC was 58.3%. When discharging with the average current value C set to 2C (2C discharge), B×C was 19, the discharge time was 8 minutes, and the dischargeable SOC was 26.7%.

[0113] The storage cell according to Reference Example 1 had an improved liquid retention amount of the negative electrode after 300 cycles, a dischargeable SOC in 1C discharge, and a dischargeable SOC in 2C discharge compared to the storage cell according to Comparative Example 1.

[0114] The power storage cells according to Examples 1 to 5 all had improved liquid retention in the negative electrode after 300 cycles, dischargeable SOC at 1C discharge, and dischargeable SOC at 2C discharge, as compared with the power storage cell according to Comparative Example 1.

[0115] The power storage cells according to Examples 1 to 4 all had improved liquid retention in the negative electrode after 300 cycles, dischargeable SOC at 1C discharge, and dischargeable SOC at 2C discharge, as compared with the power storage cell according to Reference Example 1.

[0116] The power storage cells according to Examples 5 and 6 had a slightly lower dischargeable SOC at 1C discharge as compared with the power storage cell according to Reference Example 1, but had improved liquid retention in the negative electrode after 300 cycles and dischargeable SOC at 2C discharge.

[0117] From the above results, in each of Examples 1 to 6, by setting the number of electrode divisions to 2 or more, it was confirmed that the liquid retention in the negative electrode after 300 cycles (the liquid retention property can be enhanced) can be improved and the dischargeable SOC at 2C discharge can be improved, as compared with Reference Example 1. Also, the area of each of the first general portions 33 divided by the first high-density portion 34 is 600 cm 2 or more and less than 6952 (more specifically, 6900 cm 2 or less), and the same effects as described above were confirmed.

[0118] Furthermore, when the ratio of the area of the first general portion 33 surrounded by the first high-density portion 34 to the area of the first electrode composite layer 32 is B (%) and the average discharge rate during discharge is C, it was confirmed that the capacity retention effect can be enhanced by satisfying the relationship of 9 ≤ B × C < 199. More specifically, it was confirmed that the capacity retention effect can be further enhanced by satisfying the relationships of 9 ≤ B × C ≤ 115, and further 9 ≤ B × C < 99, 9 ≤ B × C ≤ 97. In the above, the value of B × C being 115 was calculated as the value at which the dischargeable SOC is approximately 60% when the reference example 1 and the example 1 are plotted and connected by a straight line in the coordinates with the horizontal axis being B × C and the vertical axis being the dischargeable SOC in 2C discharge. Furthermore, it was confirmed that the capacity retention effect can be further enhanced by satisfying the relationship of 17 ≤ B × C < 99, and more specifically 17 ≤ B × C ≤ 63 between the above B and the above C.

[0119] (Second Verification Experiment) FIG. 14 is a diagram showing the conditions and results of the second verification experiment. With reference to FIG. 14, the second verification experiment will be described.

[0120] In the second verification experiment, a storage cell with the number of electrode divisions being 3 was used in the same manner as in Example 2. In the second verification experiment, under substantially the same conditions as in the first verification experiment, the relationship between the density difference (%) between the first high-density portion and the first general portion and the dischargeable SOC (%) at 2C was investigated by changing the thickness difference between the first high-density portion and the first general portion. Note that the first high-density portion was made thicker than the first general portion. Also, the relationship between the second high-density portion and the second general portion was made the same as that between the first high-density portion and the first general portion.

[0121] When the thickness difference between the first high-density portion and the first general portion is 3%, no significant difference was observed in the density difference between the first high-density portion and the first general portion at 5%, 10%, and 15%, and a dischargeable SOC of about 80% was obtained in each case.

[0122] When the thickness difference between the first high-density part and the first general part is 2%, as the density difference between the first high-density part and the first general part ranges from 5% to 15%, the dischargeable SOC increases. When the density difference between the first high-density part and the first general part is 5%, the dischargeable SOC is approximately 53%. When the density difference between the first high-density part and the first general part is 10%, the dischargeable SOC becomes approximately 78%. When the density difference between the first high-density part and the first general part is 15%, the dischargeable SOC becomes approximately 80%.

[0123] When the thickness difference between the first high-density part and the first general part is 1%, as the density difference between the first high-density part and the first general part ranges from 5% to 15%, the dischargeable SOC increases. When the density difference between the first high-density part and the first general part is 5%, the dischargeable SOC is approximately 27%. When the density difference between the first high-density part and the first general part is 10%, the dischargeable SOC is approximately 33%. When the density difference between the first high-density part and the first general part is 15%, the dischargeable SOC is approximately 40%.

[0124] From the above experiments, it was confirmed that when the first high-density part is thicker than the first general part and the density difference between the first high-density part and the first general part is 10% or more, the dischargeable SOC is improved. Furthermore, it was confirmed that when the density of the first high-density part is 10% or more higher than that of the first general part and the high-density part is 2% or more thicker than the general part, the dischargeable SOC can be improved more effectively. The same applies to the relationship between the second high-density part and the second general part.

[0125] Note that the storage cells according to Embodiments 1 to 4 and the storage cells according to Examples 1 to 6 can also be applied to bipolar batteries having a positive electrode composite layer and a negative electrode composite layer on both sides of the current collector.

[0126] The above-described embodiments and examples disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims, and all modifications within the meaning and scope equivalent to the claims are included.

Explanation of Reference Numerals

[0127] 1 Storage cell, 10, 10A, 10B, 10C electrode body, 20 exterior body, 25N second electrode terminal, 25P first electrode terminal, 30 first electrode, 31 first electrode current collector, 32 first electrode composite layer, 33 first general part, 34 first high-density part, 35 first electrode tab, 40 second electrode, 41 second electrode current collector, 42 second electrode composite layer, 43 second general part, 44 second high-density part, 45 second electrode tab, 48 second electrode slurry, 49 protrusion, 50 separator, 70 frame member, 71 first squeegee, 75 second squeegee, 76 notch, 341 frame-shaped part, 342 partition part, 441 frame-shaped part, 442 partition part.

Claims

1. A storage cell using an electrolyte, a first electrode composite layer, a separator, and a second electrode composite layer facing the first electrode composite layer with the separator therebetween, wherein the first electrode composite layer includes a first general part and a first high-density part having a higher density than the first general part, and the first high-density part is provided so as to surround the first general part while dividing the first general part into two or more regions. The storage cell.

2. The second electrode composite layer includes a second general part and a second high-density part having a higher density than the second general part, the second high-density part is provided so as to surround the second general part, and the first general part surrounded by the first high-density part is arranged to face at least a part of the second general part surrounded by the second high-density part with the separator therebetween. The storage cell according to claim 1.

3. The second high-density part is provided so as to surround the second general part while dividing the second general part into two or more regions, and when viewed from the stacking direction in which the first electrode composite layer and the second electrode composite layer are stacked, the region of the first general part surrounded by the first high-density part and the region of the second general part surrounded by the second high-density part coincide. The storage cell according to claim 2.

4. The first high-density part has a density 10% or more higher than that of the first general part. The storage cell according to any one of claims 1 to 3.

5. When the ratio of the area of the first general part surrounded by the first high-density part to the area of the first electrode composite layer is B (%) and the average discharge rate during discharge is C, the relationship 9 ≦ B × C < 199 is satisfied. The storage cell according to any one of claims 1 to 3.

6. The power storage cell according to claim 5, wherein the relationship between B and C satisfies 17 ≦ B × C < 99.

7. The power storage cell according to any one of claims 1 to 3, wherein the thickness of the first high-density portion is thicker than the thickness of the first general portion.

8. The area of each of the first general portions divided by the first high-density portion is 600 cm ２ or more. The power storage cell according to any one of claims 1 to 3.

9. A step of disposing a frame member on a current collector and coating an electrode slurry inside the frame member; A step of forming a general film thickness portion and a thick film portion having a thickness thicker than the general film thickness portion on the coated electrode slurry; A method for manufacturing an electrode composite layer, comprising: pressing the electrode slurry on which the thick film portion is formed, and in the step of forming the thick film portion, dividing the general film thickness portion into two or more regions and forming the thick film portion so as to surround the general film thickness portion. In the step of forming the thick film portion, while dividing the general film thickness portion into two or more regions, forming the thick film portion so as to surround the general film thickness portion, and in the pressing step, forming a general portion in a portion where the general film thickness portion is formed, and forming a high-density portion having a density higher than that of the general portion in a portion where the thick film portion is formed.

9.

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