Power storage cell and method for manufacturing electrode composite layer

Abstract

The present disclosure relates to a power storage unit. This electricity storage cell uses an electrolyte solution, and is provided with a first electrode mixture layer, a separator, and a second electrode mixture layer facing the first electrode mixture layer with the separator therebetween. The first electrode alloy 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 divide the first general portion into two or more regions and surround the first general portion.

Description

Technical Field

[0001] The present disclosure relates to a power storage unit. Background Art

[0002] As a conventional power storage cell, Japanese Patent Application Laid-Open No. 2016-100278 discloses a technology for suppressing an increase in internal resistance by making the transmittance of the outer edge portions of the first electrode and the second electrode smaller than the transmittance of the central portions of the first electrode and the second electrode. Summary of the invention

[0003] During charge and discharge, the electrolyte is squeezed out from the center of the first electrode and the second electrode to the outside of the first electrode and the second electrode through the expansion and contraction of the composite layer. When the area of ​​the first electrode and the second electrode increases, the distance from the electrolyte squeezed out to the center of the composite layer to return to the outside is extended. As a result, it becomes difficult for the electrolyte squeezed out to return to the center of the composite layer, and the amount of liquid retained in the center may decrease.

[0004] The present disclosure has been made in view of the above-mentioned problems, and an object of the present disclosure is to provide a method for manufacturing a power storage cell and an electrode composite layer that can improve liquid retention.

[0005] The storage cell based on the present disclosure is a battery cell using an electrolyte. The storage cell includes: a first electrode composite layer, a separator, and a second electrode composite layer sandwiching the separator and facing the first electrode composite layer. 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. The first high-density part is arranged in a manner that divides the first general part into two or more regions and surrounds the first general part.

[0006] According to the above configuration, the first general portion of the first electrode composite layer is divided into two or more regions, and the first high-density portion surrounds the first general portion, thereby preventing the electrolyte from being squeezed out of the first electrode composite layer from each region of the divided first general portion.

[0007] In addition, compared with a configuration in which the outer edge of a single first general portion is surrounded by the first high-density portion, the distance from the first high-density portion surrounding each region of the divided first general portion to each center portion of the divided first general portion can be shortened. Therefore, even when the area of ​​the first electrode composite material layer is increased, the electrolyte squeezed out of the first electrode composite material layer can easily return to the center portion of each region of the divided first general portion, thereby improving liquid retention.

[0008] In the 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 arranged 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 portion of the second general portion surrounded by the second high-density portion with the separator sandwiched therebetween.

[0009] According to the above configuration, the first electrode mixed material layer includes the first high-density portion and the second electrode mixed material layer also includes the second high-density portion, so that the electrolyte can be prevented from being squeezed out of the second electrode mixed material layer on the second electrode mixed material layer side.

[0010] In the storage cell based on the present disclosure, the second high-density portion may be provided in a manner that divides the second general portion into two or more regions and surrounds the second general portion. In this case, when viewed from the stacking direction of the first electrode composite layer and the second electrode composite layer, the region of the first general portion surrounded by the first high-density portion may coincide with the region of the second general portion surrounded by the second high-density portion.

[0011] According to the above configuration, it is possible to improve the liquid retention in the first electrode mixed material layer and the second electrode mixed material layer, and at the same time, improve the capacity sustaining effect (dischargeable SOC).

[0012] In the electricity storage unit according to the present disclosure, the first high-density portion may have a density that is 10% or more higher than that of the first general portion.

[0013] According to the above configuration, the capacity sustaining effect can be enhanced.

[0014] In the storage unit based on the above-mentioned present disclosure, when the proportion of the area of ​​the first general part surrounded by the first high-density part in the area of ​​the first electrode composite layer is set to B (%), and the average discharge rate during discharge is set to C, the relationship of 9≤B×C<199 can be satisfied.

[0015] According to the above configuration, the capacity sustaining effect can be enhanced.

[0016] In the power storage unit according to the present disclosure, the relationship between B and C may satisfy 17≤B×C<99.

[0017] According to the above configuration, the capacity sustaining effect can be further improved.

[0018] In the power storage unit according to the present disclosure, the first high-density portion may be thicker than the first general portion.

[0019] According to the above configuration, since the first high-density portion is thicker, the function as a wall is enhanced, and the electrolyte is less likely to be discharged to the outside of the first electrode mixed material layer.

[0020] In the power storage unit according to the present disclosure, each of the first general portions divided by the first high-density portion may have an area of ​​600 cm 2 above.

[0021] Generally, if the area of ​​the electrode composite material layer becomes larger, liquid depletion is likely to occur. According to the above configuration, even if the area of ​​the first general portion is greater than the above value, by providing the above first high-density portion, the liquid retention is improved, and liquid depletion becomes less likely to occur. Thus, the capacity reduction can be suppressed.

[0022] The manufacturing method of the electrode composite layer based on the present disclosure includes: a frame member is arranged on the collector, and an electrode slurry is applied on the inner side of the frame member; a general film thickness portion and a thick film portion thicker than the general film thickness portion are formed in the applied electrode slurry; and a process of pressing the electrode slurry formed with the thick film portion. In the process of forming the thick film portion, the thick film portion is formed in a manner that divides the general film thickness portion into two or more regions and surrounds the general film thickness portion. In the pressing process, a general portion is formed in the portion where the general film thickness portion is formed, and a high-density portion having a higher density than the general portion is formed in the portion where the thick film portion is formed.

[0023] According to the above configuration, an electrode composite material layer can be manufactured in which the general portion is divided into two or more regions and the high-density portion surrounds the general portion. By using this electrode composite material layer, the liquid retention property can be improved in the same manner as described above.

[0024] The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when read in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic plan view of the power storage unit according to the first embodiment.

[0026] Figure 2 For along Figure 1 A schematic cross-sectional view of line III I I shown.

[0027] Figure 3 It is a schematic plan view of the second electrode of the power storage cell according to the first embodiment.

[0028] Figure 4 It is a schematic plan view of a first electrode of the power storage cell according to the first embodiment.

[0029] Figure 5 It is a schematic plan view showing the positional relationship between the second electrode and the first electrode of the power storage cell according to the first embodiment.

[0030] Figure 6 This is a schematic diagram showing the first step in manufacturing the second electrode mixed material layer according to the first embodiment.

[0031] Figure 7 This is a schematic diagram showing the second step in manufacturing the second electrode mixed material layer according to the first embodiment.

[0032] Figure 8 This is a schematic diagram showing the third step in manufacturing the second electrode mixed material layer according to the first embodiment.

[0033] Fig. 9 This is a schematic diagram showing the fourth step in manufacturing the second electrode mixed material layer according to the first embodiment.

[0034] Fig.10 It is a schematic plan view showing the positional relationship between the second electrode and the first electrode of the power storage cell according to the second embodiment.

[0035] Fig.11 It is a schematic plan view showing the positional relationship between the second electrode and the first electrode of the power storage cell according to the third embodiment.

[0036] Fig.12 It is a schematic plan view showing the positional relationship between the second electrode and the first electrode of the power storage cell according to the fourth embodiment.

[0037] Fig.13 It is a figure which shows the conditions and results of the 1st verification experiment.

[0038] Fig.14 It is a figure which shows the conditions and results of the second verification experiment. DETAILED DESCRIPTION

[0039] The following is a detailed description of the embodiments of the present disclosure with reference to the accompanying drawings. It should be noted that in the embodiments shown below, the same or common parts are denoted by the same reference numerals in the drawings, and the description will not be repeated.

[0040] (Implementation Method 1)

[0041] Figure 1 It is a schematic plan view of the power storage unit according to the first embodiment. Figure 2 For along Figure 1 The schematic cross-sectional view of line I II I is shown in FIG. Figure 1 and Figure 2 , the power storage unit 1 according to the first embodiment will be described.

[0042] The power storage unit 1 according to the first embodiment is used for driving a vehicle, for example, a hybrid vehicle powered by an internal combustion engine such as a gasoline engine or a diesel engine and a motor powered by a chargeable and dischargeable battery, an externally chargeable plug-in hybrid vehicle, an electric vehicle, etc.

[0043] In the first embodiment, the case where the power storage unit 1 is a laminated liquid battery is described, but it is not limited to the laminated type and may be a rectangular liquid battery. That is, the outer casing 20 described below may be composed of a rectangular metal member.

[0044] like Figure 1 and Figure 2 As shown, the power storage unit 1 according to the first embodiment includes an electrode body 10, an outer casing 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.

[0045] The outer casing 20 contains the electrode body 10 and the electrolyte. The outer casing 20 is composed of, for example, a laminate. The electrolyte contains, for example, a non-aqueous solvent and a supporting salt such as a lithium salt that generates charge carriers.

[0046] The electrode body 10 is a so-called stacked 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 formed by stacking the first electrode 30 and the second electrode 40 with the separator 50 sandwiched between them. It should be noted that the first electrode 30 and the second electrode 40 only need to be one or more sheets each.

[0047] Each first electrode 30 includes a first electrode collector 31 and a first electrode composite layer 32. The first electrode collector 31 is provided in a sheet shape. The first electrode collector 31 is a positive electrode collector. The first electrode collector 31 has a rectangular main body and a first electrode tab 35 protruding from one side of the main body.

[0048] The first electrode tabs 35 are arranged to overlap each other when viewed from the stacking direction of the first electrode 30 and the second electrode 40. The first electrode tabs 35 are connected to the first electrode terminal 25P.

[0049] The first electrode current collector 31 is formed of, for example, aluminum foil or aluminum alloy foil. A first electrode composite layer 32 is provided on the surface of the first electrode current collector 31. More specifically, a first electrode composite layer 32 is provided on each of the two surfaces of the first electrode current collector 31 in the stacking direction. It should be noted that the first electrode composite layer 32 is not provided on the first electrode pole piece 35. The first electrode composite layer 32 is a positive electrode composite layer.

[0050] The first electrode composite material 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 equal to or thicker than that of the first general portion 33.

[0051] The coating area of ​​the first electrode composite material layer 32 is, for example, 7000 cm 2 The coating area of ​​the first electrode composite material layer 32 may be 600 cm 2 Above, 1000cm 2 Above, 3000cm 2 Above, 4000cm 2 Above, 5000cm 2 Above, 6000cm 2 Above, 7000cm 2 Above, 8000cm 2 Above, 10000cm 2 In addition, the coating area of ​​the first electrode composite material layer 32 can be 7000 cm 2 Below, 8000cm 2 Below, 10000cm 2 Below, 12000cm 2 The coating area of ​​the first electrode composite material layer 32 can be 6500 cm 2 Above 7500cm 2 Even if the coating area of ​​the first electrode composite layer 32 becomes larger, the electrolyte squeezed out of the first electrode composite layer 32 can easily return to the center of each area of ​​the divided first general portion 33, thereby improving the liquid retention. In addition, the unit area weight of the first electrode composite layer 32 is, for example, 30 mg / cm 2 The weight per unit area of ​​the first electrode composite material layer 32 may be 20 mg / cm 2 Above, 30mg / cm 2 Above, 40mg / cm 2 Above, 50mg / cm 2 Above, 60mg / cm 2 The weight per unit area of ​​the first electrode composite layer 32 may be 30 mg / cm 2 Below, 40mg / cm 2 Below, 50mg / cm 2 the following.

[0052] The first electrode composite material layer 32 has a first electrode active material. The first electrode active material is, for example, a material that can absorb and release lithium. As the first electrode active material, for example, lithium cobalt oxide (LiCoO 2 ), lithium manganese oxide (LiMn 2 O 4 ), lithium nickel oxide (LiNiO 2 ) etc. In addition, as the first electrode active material, a lithium transition metal composite oxide such as a lithium nickel cobalt manganese composite oxide can be used.

[0053] Each second electrode 40 includes a second electrode collector 41 and a second electrode composite layer 42. The second electrode collector 41 is provided in a sheet shape. The second electrode collector 41 has a rectangular main body and a second electrode tab 45 protruding from one side of the main body.

[0054] The second electrode tabs 45 are arranged to overlap each other when viewed from the stacking direction of the first electrode 30 and the second electrode 40. The second electrode tabs 45 are connected to the second electrode terminal 25N.

[0055] The second electrode collector 41 is formed of, for example, copper foil. A second electrode composite layer 42 is provided on the surface of the second electrode collector 41. More specifically, a second electrode composite layer 42 is provided on each of the two sides of the second electrode collector 41 in the stacking direction. It should be noted that the second electrode composite layer 42 is not provided on the second electrode sheet 45. The second electrode composite layer 42 is a negative electrode composite layer.

[0056] The second electrode composite material layer 42 is opposite to the first electrode composite material layer 32 via the separator 50. The second electrode composite material 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 higher than that of the second general portion 43 by, for example, 10% or more. The thickness of the second high-density portion 44 may be equal to or thicker than that of the second general portion 43.

[0057] The coating area of ​​the second electrode composite material layer 42 is larger than the coating area of ​​the first electrode composite material layer 32. The coating area of ​​the second electrode composite material layer 42 is, for example, 70-50 cm 2 The coating area of ​​the second electrode composite material layer 42 may be 600 cm 2 Above, 1000cm 2 Above, 3000cm 2 Above, 4000cm 2 Above, 5000cm 2 Above, 6000cm 2 Above, 7000cm 2 Above, 8000cm 2Above, 10000cm 2 Above, 12000cm 2 The coating area of ​​the second electrode composite layer 42 can be 7000 cm 2 Below, 8000cm 2 Below, 10000cm 2 Below, 12000cm 2 The coating area of ​​the second electrode composite layer 42 can be 6500 cm 2 Above 7500cm 2 Even if the coating area of ​​the second electrode composite layer 42 becomes larger, the electrolyte squeezed out of the first electrode composite layer 32 can easily return to the center of each area of ​​the divided first general portion 33, thereby improving the liquid retention. In addition, the unit area weight of the second electrode composite layer 42 is, for example, 20 mg / cm 2 The weight per unit area of ​​the second electrode composite layer 42 may be 20 mg / cm 2 Above, 30mg / cm 2 Above, 40mg / cm 2 Above, 50mg / cm 2 The weight per unit area of ​​the first electrode composite layer 32 may be 30 mg / cm 2 Below, 40mg / cm 2 Below, 50mg / cm 2 the following.

[0058] The second electrode composite material layer 42 contains a second electrode active material. The second electrode active material is, for example, a material that can absorb and release lithium ions. As the second electrode active material, for example, a carbon material such as graphite can be used.

[0059] 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 from the second electrode composite material layer 42. As the separator 50, a resin sheet such as polyethylene (PE) or polypropylene (PP) can be used.

[0060] The first electrode terminal 25P has one end and the other end in a direction perpendicular to the stacking direction. The one end of the first electrode terminal 25P is exposed from the outer casing 20. The other end of the first electrode terminal 25P is located inside the outer casing 20.

[0061] The other end of the first electrode terminal 25P is joined to the first electrode tab 35. The joining may be performed by resistance welding, laser welding, ultrasonic welding, etc. The first electrode terminal 25P is formed of a plate-shaped metal member. Specifically, the first electrode terminal 25P is formed of an aluminum plate.

[0062] The second electrode terminal 25N has one end and the other end in a direction perpendicular to the stacking direction. The one end of the second electrode terminal 25N is exposed from the outer casing 20 . The other end of the second electrode terminal 25N is located inside the outer casing 20 .

[0063] The other end of the second electrode terminal 25N is joined to the second electrode tab 45 by welding or the like. The joining may be performed by resistance welding, 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.

[0064] Figure 3 This is a schematic plan view of the second electrode of the power storage unit according to the first embodiment. Figure 3 , the details of the second electrode 40 will be described.

[0065] like Figure 3 As shown, the second high-density portion 44 of the second electrode 40 is provided so as to divide the second general portion 43 into two regions and surround the second general portion 43. The second high-density portion 44 includes a frame-shaped portion 441 and a partition portion 442.

[0066] The frame-like portion 441 includes a first portion along the three sides of the above-mentioned main body of the second electrode collector 41, and a second portion arranged on the inner side of the remaining side of the above-mentioned main body in a manner along the remaining side. The first portion has an angular U-shape, and the second portion is arranged in a straight line. The position of the second portion is separated from the remaining side of the above-mentioned main body. As for the second portion, the distance from the remaining side of the above-mentioned main body to the second portion is longer than the distance from each of the above-mentioned three sides of the main body to the first portion. The distance from the remaining side of the above-mentioned main body to the second portion is approximately the same as the width of the first high-density portion 34 described later. The second electrode composite layer 42 is not arranged between the above-mentioned second portion and the above-mentioned remaining side.

[0067] The partition 442 is provided so as to divide the region surrounded by the frame-shaped portion 441 into two. The second general portion 43 is provided in each of the two regions divided by the partition 442. The partition 442 is provided in a straight line. The partition 442 is provided substantially parallel to the second portion.

[0068] Figure 4 This is a schematic plan view of a first electrode of the power storage unit according to the first embodiment. Figure 4 , the details of the first electrode 30 will be described.

[0069] like Figure 4As shown, the first high-density portion 34 of the first electrode 30 is provided so as to divide the first general portion 33 into two regions and surround the first general portion 33. The first high-density portion 34 includes a frame-shaped portion 341 and a partition portion 342.

[0070] The frame-shaped portion 341 is provided along the four sides of the main body of the first electrode current collector 31. The frame-shaped portion 341 can be separated from the four sides of the main body. The partition 342 is provided so as to divide the area surrounded by the frame-shaped portion 341 into two. The first general portion 33 is provided in each of the two areas divided by the partition 342. The partition 342 is provided in a straight line.

[0071] Figure 5 1 is a schematic plan view showing the positional relationship between the second electrode and the first electrode of the power storage unit according to the first embodiment. Figure 5 As shown, when viewed from the stacking direction, the first high-density portion 34 is arranged adjacent to the second high-density portion 44 .

[0072] Specifically, when viewed from the stacking direction, the frame portion 341 is adjacent to the frame portion 441. More specifically, the frame portion 341 includes a portion adjacent to the first portion on the inner side of the first portion of the frame portion 441 and a portion adjacent to the second portion on the outer side of the second portion of the frame portion 441. When viewed from the stacking direction, the partition portion 342 is adjacent to the partition portion 442.

[0073] The first general portion 33 surrounded by the first high-density portion 34 is disposed to face at least a portion of the second general portion 43 surrounded by the second high-density portion 44 with the separator 50 interposed therebetween.

[0074] In the arrangement direction of the first general portions 33, the first general portion 33 located on one side has one side facing the second general portion 43 with the partition 50 interposed therebetween. The other side facing the partition 442 with the partition 50 interposed therebetween.

[0075] In the first general portion 33 located on the other side in the arrangement direction, the portion on one side in the arrangement direction faces the second general portion 43 via the partition 50. The portion on the other side in the arrangement direction faces the second portion of the frame portion 441 via the partition 50.

[0076] Figures 6 to 9 Schematic diagram showing the first step to the fourth step in manufacturing the second electrode composite material layer according to the first embodiment. Figures 6 to 9 For convenience, the second electrode current collector 41 is omitted. Figures 6 to 9, a method for manufacturing the second electrode composite material layer 42 will be described. Since the first electrode composite material layer 32 is manufactured in substantially the same manner, the method for manufacturing the first electrode composite material layer 32 will be omitted here.

[0077] When manufacturing the second electrode composite material layer 42, Figure 6 As shown in the figure, first, a frame member 70 is arranged on the surface of the second electrode current collector 41, and the second electrode slurry 48 is applied to the inner side of the frame member using a coating device. The applied second electrode slurry 48 is spread by a first scraper 71. In the first scraper 71, the portion in contact with the second electrode slurry 48 becomes flat. By making the viscosity of the second electrode slurry 48 about 10000 mPa·s, the outer edge portion of the second electrode slurry 48 in contact with the frame member 70 becomes a film thicker than the central portion due to surface tension.

[0078] Then, if Figure 7 As shown, the second scraper 75 is used to adjust the surface shape of the second electrode paste 48. In the second scraper 75, a cutout portion 76 is provided at a portion in contact with the second electrode paste 48. The cutout portion 76 is provided in a direction away from the second electrode paste 48 (upward). The cutout portion 76 is provided at a position corresponding to the partition 442 of the second high-density portion 44. By sliding the second scraper 75 on the surface of the second electrode paste 48, a protrusion 49 is formed on the line through which the cutout portion 76 passes. The portion where the protrusion 49 is formed becomes a thick film. In this way, a thick film portion is formed by dividing a general film thickness portion into two or more regions and surrounding the general film thickness portion. The thick film portion is thicker than the general film thickness portion.

[0079] Next, the second electrode slurry 48 with the adjusted surface shape is pressed. For example, a press device such as a press roll is used to sandwich the second electrode current collector 41 and the second electrode slurry 48. Figure 8 As shown, the second electrode composite material layer 42 is formed. More specifically, the thick film portion provided at the outer edge of the second electrode paste 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) in the second electrode paste 48 becomes the second general portion 43. In this state, the second high-density portion 44 is thicker than the second general portion 43.

[0080] Next, the second electrode composite material layer 42 formed with the second high density portion 44 is pressed again. The second electrode current collector 41 and the second electrode composite material layer 42 are sandwiched by a pressurizing device such as a pressurizing roller in the same manner as described above. Fig. 9As shown, the thickness of the second high-density portion 44 and the second general portion 43 becomes substantially the same. It should be noted that the thickness of the second high-density portion 44 can be thicker than the second general portion 43. For example, the thickness of the second high-density portion 44 can be thicker than the second general portion 43 by more than 1%, or by more than 2%. Furthermore, the thickness of the second high-density portion 44 can be thicker than the second general portion 43 by more than 3%. The second high-density portion 44 formed can have a density that is, for example, 10% or more higher than that of the second general portion 43.

[0081] The first electrode mixed material layer 32 can also be formed by applying the first electrode slurry on the first electrode current collector 31 , adjusting the shape using a first squeegee and a second squeegee, and then pressing twice, similarly to the above.

[0082] In the first electrode composite material layer 32, the thickness of the first high-density portion 34 may be thicker than the first general portion 33. For example, the thickness of the first high-density portion 34 may be thicker than the first general portion 33 by more than 1%, or by more than 2%. Furthermore, the thickness of the first high-density portion 34 may be thicker than the first general portion 33 by more than 3%. The first high-density portion 34 may be formed to have a density that is, for example, 10% or more higher than that of the first general portion 33.

[0083] As described above, in the storage cell 1 according to the first embodiment, the first high-density portion 34 is provided so as to divide the first general portion 33 into two or more regions and surround the first general portion 33. Thus, it is possible to suppress the electrolyte from being squeezed out of the first electrode composite layer 32 from each region of the divided first general portion 33.

[0084] In addition, compared with a configuration in which the outer edge of a single first general portion is surrounded by the first high-density portion, the distance from the first high-density portion 34 surrounding each region of the divided first general portion 33 to each center portion of the divided first general portion 33 can be shortened. Therefore, even when the area of ​​the first electrode composite layer 32 is increased, the electrolyte squeezed out of the first electrode composite layer 32 can easily return to the center portion of each region of the divided first general portion 33, thereby improving liquid retention.

[0085] 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 so as to face at least a portion of the second general portion 43 surrounded by the second high-density portion 44 via the separator 50. Thus, on the second electrode composite material layer 42 side, it is possible to suppress the electrolyte from being squeezed out of the second electrode composite material layer 42.

[0086] In addition, since the thickness of the first high-density portion 34 is thicker than the thickness of the first general portion 33, it is difficult for the electrolyte to be discharged to the outside of the first electrode composite layer 32. Similarly, since the thickness of the second high-density portion 44 is thicker than the thickness of the second general portion 43, it is difficult for the electrolyte to be discharged to the outside of the second electrode composite layer 42.

[0087] (Implementation Method 2)

[0088] Fig.10 1 is a schematic plan view showing the positional relationship between the second electrode and the first electrode of the power storage unit according to the second embodiment. Fig.10 , the power storage unit according to the second embodiment will be described.

[0089] like Fig.10 As shown, when the electric storage cell according to the second embodiment is compared with the electric storage cell 1 according to the first embodiment, the configuration of the electrode body 10A is different. The other configurations are substantially the same.

[0090] The electrode body 10A is different from the electrode body 10 according to the first embodiment 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 .

[0091] In this embodiment, the frame-shaped 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 in such a manner as to divide the region surrounded by the frame-shaped portion 441 into two substantially equally. The second general portion 43 is arranged in the region divided into two. 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.

[0092] 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. In addition, the region of the first general portion 33 surrounded by the first high-density portion 34 does not overlap with the frame-shaped 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-shaped portion 341. Furthermore, when viewed from the stacking direction, the frame-shaped portion 341 is arranged to overlap with the frame-shaped portion 441, and the partition portion of the first high-density portion 34 is arranged to overlap with the partition portion 442 of the second high-density portion 44.

[0093] In such a configuration, the storage cell according to Embodiment 2 also obtains substantially the same effect as the storage cell according to Embodiment 1. In addition, when viewed from the stacking direction, the region of the first general portion 33 overlaps the region of the second general portion 43, thereby improving the liquid retention in the first electrode composite layer 32 and the second electrode composite layer 42 and improving the capacity retention effect (capacity maintenance rate).

[0094] (Implementation 3)

[0095] Fig.11 1 is a schematic plan view showing the positional relationship between the second electrode and the first electrode of the power storage unit according to the third embodiment. Fig.11 , the power storage unit according to the third embodiment will be described.

[0096] like Fig.11 As shown, when the electric storage cell according to the third embodiment is compared with the electric storage cell 1 according to the first embodiment, the configuration of the electrode body 10B is different. The other configurations are substantially the same.

[0097] The electrode body 10B is different from the electrode body 10 according to the first embodiment in the arrangement of the first general portion 33 and the first high-density portion 34 , and the second general portion 43 and the second high-density portion 44 .

[0098] 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 442 is provided to divide the region surrounded by the frame portion 441 into two. The areas of the two divided regions may be different from each other.

[0099] When viewed from the stacking direction, the frame-shaped portion 341 of the first high-density portion 34 is arranged so as not to overlap with the frame-shaped portion 441 of the second high-density portion 44, and is arranged at a predetermined distance from the frame-shaped portion 441 on the inner side of the frame-shaped portion 441. When viewed from the stacking direction, the partition portion 342 is arranged so as not to overlap with the partition portion 442, and is arranged at a predetermined distance from the partition portion 442.

[0100] Even when configured in this manner, the power storage unit according to the second embodiment can achieve substantially the same effects as those of the power storage unit according to the first embodiment.

[0101] (Implementation 4)

[0102] Fig.12 1 is a schematic plan view showing the positional relationship between the second electrode and the first electrode of the power storage unit according to the fourth embodiment. Fig.12 , the power storage unit involved in the fourth embodiment is described.

[0103] like Fig.12 As shown, when the electric storage cell according to the fourth embodiment is compared with the electric storage cell 1 according to the first embodiment, the configuration of the electrode body 10C is different. The other configurations are substantially the same.

[0104] The electrode body 10C is different from the electrode body 10 according to the first embodiment in the arrangement of the first general portion 33 and the first high-density portion 34 , and the second general portion 43 and the second high-density portion 44 .

[0105] 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 442 is provided to divide the region surrounded by the frame portion 441 into two substantially equal parts. The second general portion 43 is arranged in the divided region.

[0106] The first high-density portion 34 includes two frame-like portions. When viewed from the stacking direction, the two frame-like portions are respectively arranged in the region inside the frame-like portion 441 divided into two by the partition 442. The first general portion 33 is arranged inside each of the two frame-like 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 and to overlap with a portion of the second general portion 43 inside the second general portion 43.

[0107] Even when configured in this manner, the power storage unit according to the second embodiment can achieve substantially the same effects as those of the power storage unit according to the first embodiment.

[0108] (Other Modifications)

[0109] In the above-mentioned embodiments 1 to 4, the first electrode is a positive electrode, the second electrode is a negative electrode, the first electrode composite material layer 32 is a positive electrode composite material layer, and the second electrode composite material layer 42 is a negative electrode composite material layer. However, the present invention is not limited to this. That is, the first electrode can be a negative electrode, the second electrode can be a positive electrode, the first electrode composite material layer 32 can be a negative electrode composite material layer, and the second electrode composite material layer 42 can be a positive electrode composite material layer.

[0110] In the above-mentioned embodiments 1 to 4, the case where the first general portion 33 and the second general portion 43 are each divided into two is exemplified and described, but it is not limited to this, as long as at least one of the first general portion 33 and the second general portion 43 is 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.

[0111] (First verification experiment)

[0112] Fig.13 This is a diagram showing the conditions and results of the first verification experiment. Fig.13 , the first verification experiment is described.

[0113] like Fig.13 As shown, in the first verification experiment, the storage cells involved in Comparative Example 1, Reference Example 1, and Examples 1 to 6 were prepared, and the performance of each storage cell was evaluated. Specifically, at an ambient temperature of 25°C, 300 cycles of charging the SOC from 0% to 100% were performed at a current value of 0.2C, and after 5 cycles of charging the SOC from 0% to 100% at 1C, the SOC was set to 100%, and the dischargeable SOC when discharged to the lower limit voltage of 3V was evaluated. It should be noted that the current value during discharge was evaluated at 1C and 2C, respectively.

[0114] The capacity of each storage cell was set to 60 Ah. In each storage cell, the coating area of ​​the first electrode composite layer (positive electrode composite layer) was set to 7000 cm 2 , so that the first electrode (positive electrode) unit area weight is 30mg / cm 2 The coating area of ​​the second electrode composite layer (negative electrode composite layer) is 7050 cm 2 , so that the second electrode (negative electrode) unit area weight is 20mg / cm 2 .

[0115] As the power storage unit involved in Comparative Example 1, Fig.13 As shown, the number of electrode divisions is set to 0. Specifically, a storage cell is prepared in which the first electrode composite layer 32 is composed of only the first general part 33 and the first high-density part 34 is not provided. Similarly, the second electrode composite layer 42 is also composed of only the second general part 43 and the second high-density part 44 is not provided. That is, the area A of the general part surrounded by the high-density part is 0 cm 2 , the ratio B of the area A of the general part to the area of ​​the electrode composite layer is 0%.

[0116] In the storage cell involved in Comparative Example 1, the liquid retention of the negative electrode after 300 cycles is 88%. In addition, when the average current value C is discharged at 1C (1C discharge), B×C becomes 0 and the discharge time becomes 30 minutes. The dischargeable SOC becomes 50.0%. When the average current value C is discharged at 2C (2C discharge), B×C becomes 0 and the discharge time becomes 3 minutes. The dischargeable SOC becomes 10.0%.

[0117] The storage cell involved in Reference Example 1 has an electrode division number of 1. Specifically, in the first electrode composite layer 32, the outer periphery of the first general part 33 is surrounded by the first high-density part 34, and the number of the first general part 33 is 1. At this time, the area A of the first general part 33 surrounded by the first high-density part 34 is 6952 cm2 , the ratio B of the area A of the first general part 33 to the area of ​​the first electrode composite layer 32 is 99%. It should be noted that the second electrode composite layer 42 side is also set to be substantially the same as the first electrode composite layer 32. That is, the number of divisions of the second general part 43 is set to 1.

[0118] In the storage cell involved in Reference Example 1, the liquid retention of the negative electrode after 300 cycles became 91%. In addition, when the average current value C was discharged at 1C (1C discharge), B×C became 99, and the discharge time became 42 minutes. The dischargeable SOC became 70.0%. When the average current value C was discharged at 2C (2C discharge), B×C became 199, and the discharge time became 4 minutes. The dischargeable SOC became 13.3%.

[0119] As the power storage unit according to Example 1, the number of electrode divisions is set to 2. Specifically, the power storage unit according to Embodiment 2 is prepared. At this time, the area A of each first general portion 33 surrounded by the first high-density portion 34 is set to 3404 cm 2 The area A of each first general portion 33 accounts for 49% of the area of ​​the first electrode composite layer 32. It should be noted that the second electrode composite layer 42 has a substantially similar structure to the first electrode composite layer 32. That is, the number of divisions of the second general portion 43 is set to two.

[0120] In the storage cell involved in Example 1, the liquid retention of the negative electrode after 300 cycles is 97%. In addition, when the average current value C is discharged at 1C (1C discharge), B×C becomes 49, and the discharge time becomes 48 minutes. The dischargeable SOC becomes 80.0%. When the average current value C is discharged at 2C (2C discharge), B×C becomes 97, and the discharge time becomes 21 minutes. The dischargeable SOC becomes 70.0%.

[0121] The storage cell according to the second embodiment has an electrode division number of 3. Specifically, the interior of the frame portion 341 of the first high-density portion 34 is divided into three regions by two partitions 342, and the first general portion 33 is 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 is 2189 cm 2 , the ratio B of the area A of each first general part 33 to the area of ​​the first electrode composite layer 32 is 31%. It should be noted that the second electrode composite layer 42 side is also set to be substantially the same as the first electrode composite layer 32. That is, the number of divisions of the second general part 43 is set to 3.

[0122] In the storage cell involved in Example 2, the liquid retention of the negative electrode after 300 cycles is 99%. In addition, when the average current value C is discharged at 1C (1C discharge), B×C becomes 31, and the discharge time becomes 50 minutes. The dischargeable SOC becomes 83.3%. When the average current value C is discharged at 2C (2C discharge), B×C becomes 63, and the discharge time becomes 23 minutes. The dischargeable SOC becomes 76.7%.

[0123] The storage cell according to the third embodiment has an electrode division number of 4. Specifically, the interior of the frame-shaped portion 341 of the first high-density portion 34 is divided into four regions by a plurality of partitions 342, and the first general portion 33 is 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 is 1558 cm 2 The ratio B of the area A of each first general part 33 to the area of ​​the first electrode composite layer 32 is 22%. It should be noted that the second electrode composite layer 42 is also configured to be substantially the same as the first electrode composite layer 32. That is, the number of divisions of the second general part 43 is set to 4.

[0124] In the storage cell involved in Example 3, the liquid retention of the negative electrode after 300 cycles is 99%. In addition, when the average current value C is discharged at 1C (1C discharge), B×C becomes 22, and the discharge time becomes 51 minutes. The dischargeable SOC becomes 85.0%. When the average current value C is discharged at 2C (2C discharge), B×C becomes 45, and the discharge time becomes 24 minutes. The dischargeable SOC becomes 80.0%.

[0125] As the storage cell involved in the fourth embodiment, the number of electrode divisions is set to 5. Specifically, the interior of the frame-shaped portion 341 of the first high-density portion 34 is divided into five regions by a plurality of partitions 342, and the first general portion 33 is arranged in each of the five divided regions. At this time, the area A of each first general portion 33 surrounded by the first high-density portion 34 is set to 1160 cm 2 , the ratio B of the area A of each first general part 33 to the area of ​​the first electrode composite layer 32 is 17%. It should be noted that the second electrode composite layer 42 side is also set to be substantially the same as the first electrode composite layer 32. That is, the number of divisions of the second general part 43 is set to 5.

[0126] In the storage cell involved in Example 4, the liquid retention of the negative electrode after 300 cycles became 99%. In addition, when the average current value C was discharged at 1C (1C discharge), B×C became 17 and the discharge time became 52 minutes. The dischargeable SOC became 86.7%. When the average current value C was discharged at 2C (2C discharge), B×C became 33 and the discharge time became 24 minutes. The dischargeable SOC became 80.0%.

[0127] The storage cell according to the fifth embodiment has an electrode division number of 6. Specifically, the interior of the frame-shaped portion 341 of the first high-density portion 34 is divided into six regions by a plurality of partitions 342, and the first general portion 33 is disposed in each of the six divided regions. At this time, the area A of each first general portion 33 surrounded by the first high-density portion 34 is 879 cm 2 , the ratio B of the area A of each first general part 33 to the area of ​​the first electrode composite layer 32 is 13%. It should be noted that the second electrode composite layer 42 side is also set to be substantially the same as the first electrode composite layer 32. That is, the number of divisions of the second general part 43 is set to 6.

[0128] In the storage cell involved in Example 5, the liquid retention of the negative electrode after 300 cycles is 94%. In addition, when the average current value C is discharged at 1C (1C discharge), B×C becomes 13, and the discharge time becomes 40 minutes. The dischargeable SOC becomes 66.7%. When the average current value C is discharged at 2C (2C discharge), B×C becomes 25, and the discharge time becomes 18 minutes. The dischargeable SOC becomes 60.0%.

[0129] The storage cell according to the sixth embodiment has an electrode division number of 7. Specifically, the interior of the frame-shaped portion 341 of the first high-density portion 34 is divided into seven regions by a plurality of partitions 342, and the first general portion 33 is disposed in each of the seven divided regions. At this time, the area A of each first general portion 33 surrounded by the first high-density portion 34 is 664 cm 2 The ratio B of the area A of each first general part 33 to the area of ​​the first electrode composite layer 32 is 9%. It should be noted that the second electrode composite layer 42 is also configured to be substantially the same as the first electrode composite layer 32. That is, the number of divisions of the second general part 43 is set to 7.

[0130] In the storage cell involved in Example 5, the liquid retention of the negative electrode after 300 cycles is 92%. In addition, when the average current value C is discharged at 1C (1C discharge), B×C becomes 9, and the discharge time becomes 35 minutes. The dischargeable SOC becomes 58.3%. When the average current value C is discharged at 2C (2C discharge), B×C becomes 19, and the discharge time becomes 8 minutes. The dischargeable SOC becomes 26.7%.

[0131] The power storage cell according to Reference Example 1 is improved in the liquid retention amount of the negative electrode after 300 cycles, the dischargeable SOC under 1C discharge, and the dischargeable SOC under 2C discharge, compared with the power storage cell according to Comparative Example 1.

[0132] The storage cells according to Examples 1 to 5 all had improved negative electrode liquid retention after 300 cycles, dischargeable SOC under 1C discharge, and dischargeable SOC under 2C discharge, compared to the storage cell according to Comparative Example 1.

[0133] The storage cells according to Examples 1 to 4 all had improved negative electrode liquid retention after 300 cycles, dischargeable SOC under 1C discharge, and dischargeable SOC under 2C discharge, compared to the storage cell according to Reference Example 1.

[0134] The power storage cells according to Examples 5 and 6 have slightly lower dischargeable SOC at 1C discharge than the power storage cell according to Reference Example 1, but the liquid retention amount of the negative electrode after 300 cycles and the dischargeable SOC at 2C discharge are improved.

[0135] Based on the above results, it was confirmed that in each of Examples 1 to 6, by making the number of electrode divisions 2 or more, the liquid retention of the negative electrode after 300 cycles can be increased (the liquid retention can be improved) compared with Reference Example 1, and the dischargeable SOC under 2C discharge can be increased. In addition, by making the area of ​​each of the first general parts 33 divided by the first high-density part 34 600 cm 2 Over and less than 6952cm 2 (More specifically, 6900 cm 2 The same effect as above was confirmed.

[0136] Furthermore, when the ratio of the area of ​​the first general part 33 surrounded by the first high-density part 34 to the area of ​​the first electrode composite material layer 32 is set as B (%), and the average discharge rate during discharge is set as C, it is confirmed that the capacity continuation effect can be improved by satisfying the relationship of 9≤B×C<199. More specifically, it is confirmed that the capacity continuation effect can be further improved by satisfying the relationship of 9≤B×C≤115, further 9≤B×C<99, and 9≤B×C≤97. It should be noted that in the above, for the value of B×C being 115, when Reference Example 1 and Example 1 are plotted in the coordinates of the dischargeable SOC under 2C discharge with the horizontal axis being B×C and the vertical axis being connected by a straight line, it is calculated as a value of about 60% that the dischargeable SOC is calculated. Furthermore, it is confirmed that the capacity continuation effect can be further improved by satisfying the relationship between the above B and the above C of 17≤B×C<99, more specifically 17≤B×C≤63.

[0137] (Second verification experiment)

[0138] Fig.14 This is a diagram showing the conditions and results of the second verification experiment. Fig.14 , the second verification experiment is described.

[0139] 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 conditions substantially the same as those in the first verification experiment, the thickness difference between the first high-density portion and the first general portion was changed, and the relationship between the density difference (%) between the first high-density portion and the first general portion and the dischargeable SOC (%) at 2C was examined. It should be noted that the thickness of the first high-density portion was made thicker than the thickness of the first general portion. In addition, the relationship between the second high-density portion and the second general portion was also the same as the relationship between the first high-density portion and the first general portion.

[0140] When the thickness difference between the first high-density portion and the first general portion was 3%, the density differences between the first high-density portion and the first general portion were 5%, 10%, and 15%, and no significant difference was found. In any case, a dischargeable SOC of about 80% was obtained.

[0141] When the thickness difference between the first high-density portion and the first general portion is 2%, the density difference between the first high-density portion and the first general portion increases from 5% to 15%, thereby increasing the dischargeable SOC. When the density difference between the first high-density portion and the first general portion is 5%, the dischargeable SOC is about 53%, and when the density difference between the first high-density portion and the first general portion is 10%, the dischargeable SOC is about 78%. When the density difference between the first high-density portion and the first general portion is 15%, the dischargeable SOC is about 80%.

[0142] When the thickness difference between the first high-density portion and the first general portion is 1%, the density difference between the first high-density portion and the first general portion increases from 5% to 15%, thereby increasing the dischargeable SOC. When the density difference between the first high-density portion and the first general portion is 5%, the dischargeable SOC is about 27%. When the density difference between the first high-density portion and the first general portion is 10%, the dischargeable SOC is about 33%. When the density difference between the first high-density portion and the first general portion is 15%, the dischargeable SOC is about 40%.

[0143] Through the above experiments, it was confirmed that the dischargeable SOC was improved by making the thickness of the first high-density portion thicker than the first general portion and the density difference between the first high-density portion and the first general portion greater than 10%. It was further confirmed that the dischargeable SOC could be more effectively improved by making the density of the first high-density portion greater than 10% higher than the first general portion and the high-density portion greater than 2% thicker than the general portion. The relationship between the second high-density portion and the second general portion was the same.

[0144] It should be noted that the power storage cells according to the above-described first to fourth embodiments and the power storage cells according to the first to sixth examples can also be applied to a bipolar battery having a positive electrode composite layer and a negative electrode composite layer on both sides of a current collector.

[0145] Although the embodiments of the present invention have been described, the embodiments disclosed this time should be considered to be illustrative in all aspects 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 intended to be included.

Claims

1. A power storage unit, which is a power storage unit using an electrolyte, comprising: a first electrode composite material layer, a separator, and a second electrode composite material layer facing the first electrode composite material layer with the separator interposed therebetween. The first electrode composite material 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 divide the first general portion into two or more regions and surround the first general portion.

2. The power storage unit according to claim 1, wherein: The second electrode composite material layer includes a second general portion and a second high-density portion having a higher density than the second general portion. The second high-density portion is arranged to surround the second general portion. The first general portion surrounded by the first high-density portion is arranged to face at least a portion of the second general portion surrounded by the second high-density portion with the separator interposed therebetween.

3. The power storage unit according to claim 2, wherein: The second high-density portion is provided in a manner to divide the second general portion into two or more regions and to surround the second general portion. When viewed from the stacking direction of the first electrode mix layer and the second electrode mix layer, the region of the first general portion surrounded by the first high-density portion coincides with the region of the second general portion surrounded by the second high-density portion.

4. The power storage unit according to any one of claims 1 to 3, wherein: The first high-density portion has a density that is 10% or more higher than that of the first general portion.

5. The power storage unit according to any one of claims 1 to 3, wherein: 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 is satisfied.

6. The power storage unit according to claim 5, wherein: The relationship between B and C satisfies 17≤B×C<99.

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

8. The power storage unit according to any one of claims 1 to 3, wherein: Each area of ​​the first general part divided by the first high-density part is 600 cm 2 above.

9. A method for manufacturing an electrode composite layer, comprising: The step of disposing a frame member on the current collector and applying an electrode slurry on the inner side of the frame member; The process of forming a general film thickness portion and a thick film portion thicker than the general film thickness portion in the applied electrode slurry; and the process of pressing the electrode slurry having the thick film portion formed thereon. In the step of forming the thick film portion, the thick film portion is formed so as to divide the general film thickness portion into two or more regions and surround the general film thickness portion. In the pressing step, a general portion is formed in the portion where the general film thickness portion is formed, and a high-density portion having a higher density than the general portion is formed in the portion where the thick film portion is formed.

Images