All-solid-state battery and method for manufacturing same

Abstract

Provided is a laminated all-solid-state battery which hardly causes a decrease in energy density. This all-solid-state battery comprises: a plurality of laminates (3) in which a positive electrode layer (31) and a negative electrode layer (32) are laminated; a positive electrode current collector (4); and a negative electrode current collector (6). The positive electrode layers (31) face each other and the negative electrode layers (32) face each other between the laminated plurality of laminates (3). The positive electrode current collector (4) is folded back along one side surface (3a) of each of first and second laminates (3) so as to contact the positive electrode layer (31) of the first laminate (3) and the positive electrode layer (31) of the second laminate (3) laminated on the first laminate (3). The negative electrode current collector (6) is folded back along the other side surface (3b) of each of second and third laminates (3) on the side different from the one side surface (3a) so as to contact the negative electrode layer (32) of the second laminate (3) and the negative electrode layer (32) of the third laminate (3) laminated on the second laminate (3).

Description

All-solid-state battery and method for manufacturing the same

[0001] The present invention relates to an all-solid-state battery and the like.

[0002] To increase the capacity of an all-solid-state battery including a solid electrolyte layer, multiple laminates (single batteries) each including a positive electrode layer, a solid electrolyte layer, and a negative electrode layer may be stacked in parallel. In such a stacking structure, the laminates are stacked so that the electrode layers of the same polarity of each laminate overlap. In addition, in this stacking structure, the current collectors of the positive and negative electrodes provided in each laminate are connected to each other with the same polarity.

[0003] For example, Patent Document 1 describes a method in which tabs protruding from current collectors of the same polarity are overlapped and connected to a conductive member by welding. The connection can be achieved by welding, which heats and melts the materials, or by ultrasonic bonding, which uses ultrasonic waves to connect the materials in a solid state.

[0004] Japanese Patent Application Publication No. 2016-115491

[0005] However, there is a problem in that the energy density is likely to decrease at the connection portion where the connection is made as described above.

[0006] An object of one embodiment of the present invention is to provide a stacked-type all-solid-state battery that is less susceptible to a decrease in energy density.

[0007] In order to solve the above-described problems, an all-solid-state battery according to one aspect of the present invention includes a plurality of laminates each including a first electrode layer, a second electrode layer having a polarity opposite to that of the first electrode layer, and a solid electrolyte layer interposed between the first electrode layer and the second electrode layer; a first current collector provided so as to contact the first electrode layer; and a second current collector provided so as to contact the second electrode layer, wherein the plurality of laminates are stacked such that the first electrode layers and the second electrode layers of each laminate face each other, and the first current collector is provided between the first and second electrode layers of each of the plurality of laminates. the second current collector is folded back along first side surfaces of the first and second stacks so as to come into contact with the first electrode layer of a first stack and the first electrode layer of a second stack of the plurality of stacks stacked on the first stack, and the second current collector is folded back along second side surfaces of the second and third stacks, on the side opposite to the first side surface, so as to come into contact with the second electrode layer of the second stack of the plurality of stacks and the second electrode layer of a third stack of the plurality of stacks stacked on the second stack.

[0008] In order to solve the above-mentioned problems, a manufacturing method of an all-solid-state battery according to one aspect of the present invention is a manufacturing method of an all-solid-state battery including: a laminate in which a first electrode layer, a second electrode layer having a polarity opposite to that of the first electrode layer, and a solid electrolyte layer interposed between the first electrode layer and the second electrode layer are stacked; a first current collector provided so as to be in contact with the first electrode layer; and a second current collector provided so as to be in contact with the second electrode layer, the manufacturing method including the steps of: stacking a plurality of the laminates such that the first electrode layers overlap each other and the second electrode layers overlap each other; and stacking the first current collector on the first current collector, which is the lowest layer in the laminate before being arranged in the stacking step. a first placing step of placing the second current collector below an electrode layer; a second placing step of placing the second current collector on the second electrode layer that is the uppermost layer of the laminate after being placed in the stacking step; a first folding step of folding back and superimposing the first current collector onto the first electrode layer that is the uppermost layer of the laminate that was stacked on the laminate in the stacking step, along a first side surface of the two laminates; and a second folding step of folding back and superimposing the second current collector onto the second electrode layer that is the uppermost layer of the laminate that was stacked on the two laminates in the stacking step, along a second side surface of the two laminates that is on the side opposite to the first side surface.

[0009] According to one aspect of the present invention, it is possible to provide a stacked-type all-solid-state battery that is less likely to cause a decrease in energy density.

[0010] FIG. 1 is a plan view showing the configuration of all-solid-state batteries according to embodiments 1 and 2 of the present invention. FIG. 2 is a side view showing the structure of a battery unit included in the all-solid-state battery according to embodiment 1 of the present invention. FIG. 3 is another side view showing the structure of the all-solid-state battery according to embodiment 1 of the present invention. FIG. 4 is a diagram showing a manufacturing process for the all-solid-state battery according to embodiment 1 of the present invention. FIG. 5 is a diagram showing a manufacturing process for the all-solid-state battery subsequent to the manufacturing process shown in FIG. 6. FIG. 7 is a diagram showing the structure of a battery unit included in the all-solid-state battery according to embodiment 2 of the present invention. FIG. 8 is a diagram showing a manufacturing process for the all-solid-state battery subsequent to the manufacturing process shown in FIG.

[0011] [First Embodiment] Hereinafter, one embodiment of the present invention will be described in detail.

[0012] <General Configuration of All-Solid-State Battery> In each embodiment including this embodiment, an all-solid-state secondary battery using a lithium ion conductive solid electrolyte, i.e., an all-solid-state lithium ion secondary battery, will be described as an example of an all-solid-state battery. However, it goes without saying that the all-solid-state battery according to the present invention is not limited to an all-solid-state lithium ion secondary battery.

[0013] Fig. 1 is a plan view showing the configuration of an all-solid-state battery 101 according to this embodiment. Fig. 2 is a side view showing the structure of a battery unit 1 included in the all-solid-state battery 101. Fig. 3 is another side view showing the structure of the battery unit 1. Fig. 2 shows the side of the battery unit 1 as viewed from direction A in Fig. 1. Fig. 3 also shows the side of the battery unit 1 as viewed from direction B in Fig. 1.

[0014] As shown in Fig. 1 , the all-solid-state battery 101 includes a battery unit 1 and a laminated exterior body 2. The battery unit 1 is enclosed in the laminated exterior body 2. As also shown in Figs. 2 and 3 , the battery unit 1 includes a plurality of laminated bodies 3, a plurality of positive electrode current collectors 4 (first current collectors), a positive electrode current collector 5, a plurality of negative electrode current collectors 6 (second current collectors), sealants 7 and 8, and an insulating part 10. The battery unit 1 is configured by connecting a plurality of laminated bodies 3 in parallel, each of which can function as a battery on its own.

[0015] <Details of Battery Unit> As shown in Figures 2 and 3, the laminate 3 has a positive electrode layer 31 (first electrode layer), a negative electrode layer 32 (second electrode layer), and a solid electrolyte layer 33. The positive electrode layer 31 is an electrode layer having a positive polarity. The negative electrode layer 32 is an electrode layer having a polarity opposite to that of the positive electrode layer 31, i.e., a negative polarity. The solid electrolyte layer 33 is a layer formed of a solid electrolyte and is interposed between the positive electrode layer 31 and the negative electrode layer 32. The laminates 3 are stacked such that the positive electrode layers 31 and the negative electrode layers 32 of each laminate 3 face each other. The planar shape of the laminate 3 is square (e.g., rectangular).

[0016] 2 includes seven stacks 3. In this stack structure, the positive electrode layer 31 is disposed on the lower side and the negative electrode layer 32 is disposed on the upper side in the stacks 3 disposed in the first (lowest), third, fifth, and seventh (uppermost) stages, i.e., odd-numbered stages. On the other hand, the positive electrode layer 31 is disposed on the upper side and the negative electrode layer 32 is disposed on the lower side in the stacks 3 disposed in the second, fourth, and sixth stages, i.e., even-numbered stages.

[0017] The arrangement of the positive electrode layer 31 and the negative electrode layer 32 in each laminate 3 is not limited to the above example, and may be reversed. Also, the number of laminates 3 in the battery unit 1 is one example, and any other number of laminates 3 may be stacked as long as it is plural.

[0018] The positive electrode layer 31 is formed of a composite (mixture) of a positive electrode active material and a solid electrolyte, or of the positive electrode active material alone. The positive electrode active material may be a material commonly used for positive electrode active materials in the field of all-solid-state batteries. Examples of the positive electrode active material include lithium-containing oxides (e.g., lithium cobalt oxide (LiCoO), lithium nickel oxide (LiNiO), and lithium manganese oxide (LiMnO, etc.)).

[0019] The negative electrode layer 32 is formed of a composite (mixture) of a negative electrode active material and a solid electrolyte, or of only the negative electrode active material. The negative electrode active material may be any material commonly used in the field of all-solid-state batteries. Examples of the negative electrode active material include graphite (natural graphite, artificial graphite, etc.), carbon materials (graphite carbon fiber, resin-baked carbon, etc.), tin, lithium, oxides, sulfides, nitrides, alloys, etc., regardless of the form of powder, foil, etc.

[0020] The solid electrolytes used in the positive electrode layer 31, the negative electrode layer 32, and the solid electrolyte layer 33 are materials that are commonly used in the field of lithium ion batteries. Examples of such solid electrolytes include organic compounds, inorganic compounds, and materials made of both organic and inorganic compounds. Among inorganic compounds, Li ２ S-P ２ S ５Sulfides such as these have superior ionic conductivity compared to other inorganic compounds.

[0021] The positive electrode current collector 4 is folded back so as to contact the surfaces of the positive electrode layers 31 of the two stacked laminates 3. Specifically, the positive electrode current collector 4 has two contact portions 41 and a folded back portion 42.

[0022] The contact portion 41 is provided so as to be in contact with the surface of the positive electrode layer 31, and is disposed so as to face each other with the two stacked laminates 3 therebetween. The folded portion 42 is provided between the two contact portions 41. The folded portion 42 is a portion where the positive electrode current collector 4 is folded along one side surface 3 a (first side surface) of the two stacked laminates 3.

[0023] In this way, the positive electrode current collector 4 is folded at the folding portion 42. As a result, one contact portion 41 comes into contact with the positive electrode layer 31 included in the lower laminate 3 (first laminate) of the two stacked laminates 3. The other contact portion 41 comes into contact with the positive electrode layer 31 included in the laminate 3 (second laminate) stacked on the lower laminate 3.

[0024] A plurality of positive electrode current collectors 4 are provided, each of which is configured to contact two positive electrode layers 31 in the first and second laminates.

[0025] The positive electrode current collector 5 is provided so as to be in contact with the surface of the positive electrode layer 31 of the uppermost laminate 3. The positive electrode current collector 5 does not need to be folded over like the positive electrode current collector 4, and is therefore formed to have an area slightly larger than the surface area of ​​the laminate 3.

[0026] The negative electrode current collector 6 has a shape that is folded back so as to contact the surfaces of the negative electrode layers 32 of the two stacked laminates 3. Specifically, the negative electrode current collector 6 has two contact portions 61 and a folded back portion 62.

[0027] The contact portion 61 is provided so as to be in contact with the surface of the negative electrode layer 32, and is disposed so as to face each other with the two stacked laminates 3 therebetween. The folded portion 62 is provided between the two contact portions 61. The folded portion 62 is a portion where the negative electrode current collector 6 is folded along the other side surface 3b (second side surface) of the two stacked laminates 3.

[0028] In this way, the negative electrode current collector 6 is folded back at the folded back portion 62. As a result, one contact portion 61 contacts the negative electrode layer 32 included in the lower laminate 3 (second laminate) of the two stacked laminates 3. The other contact portion 61 contacts the negative electrode layer 32 included in the laminate 3 (third laminate) stacked on the lower laminate 3. In FIG. 2 , the first laminate corresponds to the bottommost laminate 3, the second laminate corresponds to the laminate 3 stacked on the first laminate, and the third laminate corresponds to the laminate 3 stacked on the second laminate. The third laminate also serves as the first laminate. In this way, the first to third laminates are repeatedly stacked.

[0029] A plurality of negative electrode current collectors 6 are provided, each of which is in contact with two negative electrode layers 32 in the second and third stacks.

[0030] With the above-described structure, between the two stacked laminates 3, the two opposing positive electrode layers 31 are electrically connected to each other via the contact portion 41 of the positive electrode current collector 4, and the two opposing negative electrode layers 32 are electrically connected to each other via the contact portion 61 of the negative electrode current collector 6. Furthermore, the lower positive electrode layer 31 of the lowermost laminate 3 contacts the lower contact portion 41 of the lowermost positive electrode current collector 4. The upper negative electrode layer 32 of the uppermost laminate 3 contacts the upper contact portion 61 of the uppermost negative electrode current collector 6.

[0031] As a result, in the plurality of stacks 3, the positive electrode layers 31 are electrically connected to each other by the plurality of positive electrode current collectors 4, and the negative electrode layers 32 are electrically connected to each other by the plurality of negative electrode current collectors 6. Therefore, the stacks 3 in the battery unit 1 are connected in parallel.

[0032] Any one of the positive electrode current collectors 4 has a tab 4 a (first tab) that protrudes from the contact portion 41 to the side of the positive electrode layer 31. Any one of the negative electrode current collectors 6 has a tab 6 a (second tab) that protrudes from the contact portion 61 to the side of the negative electrode layer 32.

[0033] In the configuration shown in Fig. 2, tab 4a is provided on contact portion 41 below the lowest positive electrode current collector 4. Tab 6a is provided on contact portion 61 below the lowest negative electrode current collector 6. As shown in Fig. 1, tabs 4a, 6a are arranged on the short sides of the rectangular laminate 3 and are formed so as to extend in the direction of the long sides of the laminate 3 and thereby be exposed to the outside of the laminate outer casing 2. The tabs 4a, 6a formed in this manner enable the positive electrode current collector 4 and the negative electrode current collector 6 to be electrically connected to predetermined external locations, respectively.

[0034] The positive electrode current collector 4 and the negative electrode current collector 6 are formed in a foil shape from a metal such as aluminum, copper, or nickel. The tabs 4 a and 6 a are also formed in a foil shape from the same metal material as the positive electrode current collector 4 and the negative electrode current collector 6.

[0035] The sealant 7 is provided in the sealed portion of the laminate exterior body 2 so that the tab 4a passes through the sealant 7. The sealant 8 is provided in the sealed portion of the laminate exterior body 2 so that the tab 6a passes through the sealant 8. The sealants 7 and 8 are provided in place of the tabs 4a and 6a, which do not have good adhesion to the laminate film (resin) that forms the inside of the laminate exterior body 2, to improve adhesion to the laminate film and airtightness around the tabs 4a and 6a. The sealants 7 and 8 are made of resin such as PP (polypropylene) or PET (poly ethylene terephthalate).

[0036] The insulating portion 10 is disposed on the outer periphery of the laminate 3 at a distance from the laminate 3, and is provided to ensure electrical insulation between the contact portion 41 of the positive electrode current collector 4 and the contact portion 61 of the negative electrode current collector 6. The insulating portion 10 is formed in a frame shape that surrounds the laminate 3. For convenience, only the cross-sectional structure of the insulating portion 10 is shown in Figs. 2 and 3.

[0037] The insulating portion 10 has an insulating layer 11 and two adhesive layers 12. The insulating layer 11 is formed of an electrically insulating material, such as PET. The adhesive layers 12 are disposed on both sides of the insulating layer 11 and are provided so as to sandwich the insulating layer 11. The adhesive layers 12 are formed of double-sided tape and adhere to the insulating layer 11 as well as to the surfaces of the contact portions 41 and 61.

[0038] The adhesive layer 12 adheres closely to the contact portion 41 of the positive electrode current collector 4 and the contact portion 61 of the negative electrode current collector 6, thereby fixing the positions of the positive electrode current collector 4 and the negative electrode current collector 6. As a result, the laminate 3 disposed between the positive electrode current collector 4 and the negative electrode current collector 6 is fixed in a state of contact with the contact portions 41, 61.

[0039] As described above, the insulating portion 10 is disposed on the outer periphery of the laminate 3. Therefore, the folded portion 42 of the positive electrode current collector 4 is disposed along the side surface 3 a of the laminate 3, but is also disposed along the outer periphery of the insulating portion 10. Furthermore, the folded portion 62 of the negative electrode current collector 6 is disposed along the side surface 3 b of the laminate 3, but is also disposed along the outer periphery of the insulating portion 10.

[0040] <Manufacturing of All-Solid-State Battery> The manufacturing (manufacturing method) of the all-solid-state battery 101 configured as above will be described. Fig. 4 is a diagram showing the manufacturing process of the all-solid-state battery 101. Fig. 5 is a diagram showing the manufacturing process of the all-solid-state battery 101 subsequent to the manufacturing process shown in Fig. 4.

[0041] 4, first, the positive electrode current collector 4 is placed in an unfolded state on a workbench (not shown), and the insulating part 10 is placed thereon (step S1). In step S1, the insulating part 10 is placed on the side of the positive electrode current collector 4 where the tab 4a is provided. In addition, the sealant 7 is attached to the tab 4a.

[0042] Next, the stack 3 (first stage) is placed inside the insulating portion 10 on the positive electrode current collector 4 with the negative electrode layer 32 facing up, i.e., with the positive electrode layer 31 facing down (step S2).

[0043] Next, the negative electrode current collector 6 is placed in a spread state on the laminate 3 and the insulating portion 10, and the insulating portion 10 is placed on the spread negative electrode current collector 6 (step S3). In step S3, the negative electrode current collector 6 is placed so that the tab 6a is adjacent to the tab 4a, and the insulating portion 10 is placed on the side of the negative electrode current collector 6 where the tab 6a is provided. In addition, a portion of the negative electrode current collector 6 where the insulating portion 10 is not placed (a portion that will become the contact portion 61) is spread on the opposite side of the portion of the positive electrode current collector 4 where the insulating portion 10 is not placed (a portion that will become the contact portion 41). In addition, a sealant 8 is attached to the tab 6a.

[0044] Next, the stack 3 (second stage) is placed inside the insulating portion 10 on the negative electrode current collector 6 with the positive electrode layer 31 facing up, i.e., with the negative electrode layer 32 facing down (step S4).

[0045] Then, the unfolded portion of the positive electrode current collector 4 is folded back so as to cover the laminate 3 arranged in step S4 (step S5). In step S5, the folded back portion of the positive electrode current collector 4 is brought into contact with the surface of the positive electrode layer 31 of the laminate 3, thereby forming the contact portion 41.

[0046] Furthermore, the positive electrode current collector 4 is placed in a spread state on the contact portion 41, and the insulating portion 10 is placed thereon (step S6). In step S6, the portion of the positive electrode current collector 4 where the insulating portion 10 is not placed (the portion that will become the contact portion 41) is spread on the opposite side to the portion of the negative electrode current collector 6 where the insulating portion 10 is not placed (the portion that will become the contact portion 61).

[0047] Next, the stack 3 (third stage) is placed inside the insulating portion 10 on the positive electrode current collector 4 with the negative electrode layer 32 facing up, i.e., with the positive electrode layer 31 facing down (step S7).

[0048] Then, the unfolded portion of the negative electrode current collector 6 is folded back so as to cover the laminate 3 arranged in step S7 (step S8). In step S8, the folded back portion of the negative electrode current collector 6 is brought into contact with the surface of the negative electrode layer 32 of the laminate 3, thereby forming the contact portion 61.

[0049] Thereafter, steps S3 to S8 are performed again to stack the fourth and fifth stacks 3. Furthermore, steps S3 to S5 are performed again to stack the sixth stack 3. However, in step S3, which is performed again, a negative electrode current collector 6 without a tab 6a is placed.

[0050] 5 , a positive electrode current collector 5 is placed on the contact portion 41 of the positive electrode current collector 4 formed in the three repeated steps of step S5 (step S9). After that, an insulating portion 10 is placed on the positive electrode current collector 5, and the stack 3 (seventh layer) is placed inside the insulating portion 10 on the positive electrode current collector 5 with the negative electrode layer 32 facing up, i.e., with the positive electrode layer 31 facing down (step S10). Then, the unfolded portion of the negative electrode current collector 6 is folded back to cover the stack 3 placed in step S10 (step S11), thereby completing the battery unit 1.

[0051] Finally, the completed battery unit 1 is sealed in the laminated exterior body 2. In sealing, the four sides of two laminated films arranged above and below the battery unit 1 are heat-sealed. This seals the battery unit 1 in the laminated exterior body 2 with the tabs 4 a and 6 a exposed.

[0052] In the above manufacturing process, steps S2, S4, S7, and S10 are performed to stack the first to seventh stacks 3 so that the positive electrode layers 31 and the negative electrode layers 32 overlap each other (stacking step). Steps S1 and S6 are performed to place the positive electrode current collector 4 below the bottommost positive electrode layer 31 of the stack 3 before the stacking step (first placement step). Step S3 is performed to place the negative electrode current collector 6 on the topmost negative electrode layer 32 of the stack 3 after the stacking step (second placement step). Step S5 is performed to fold the positive electrode current collector 4 over the topmost positive electrode layer 31 of the stack 3 stacked on top of the stack 3 in the stacking step by folding it along the side surfaces 3 a of the two stacks 3 (first folding step). In addition, in steps S8 and S11, the negative electrode current collector 6 is folded back along the side surfaces 3b of the two laminates 3 and placed on top of the uppermost negative electrode layer 32 of the laminate 3 that was stacked on top of the two laminates 3 in the stacking process (second folding process).

[0053] Effects of the Embodiment As described above, the all-solid-state battery 101 according to the present embodiment includes a plurality of laminates 3, a plurality of positive electrode current collectors 4, and a plurality of negative electrode current collectors 6. The plurality of laminates 3 are stacked such that the positive electrode layers 31 face each other and the negative electrode layers 32 face each other. The contact portion 41 of the positive electrode current collector 4 contacts the positive electrode layer 31 of a first laminate among the plurality of laminates 3 and the positive electrode layer 31 of a second laminate among the plurality of laminates 3 stacked on the first laminate. The positive electrode current collector 4 is folded back at the fold portion 42 along the side surfaces 3 a of the first and second laminates. The contact portion 61 of the negative electrode current collector 6 contacts the negative electrode layer 32 of a second laminate among the plurality of laminates 3 and the negative electrode layer 32 of a third laminate among the plurality of laminates 3 stacked on the second laminate. The negative electrode current collector 6 is folded back at the folded back portion 62 along the side surfaces 3 b of the second and third laminates.

[0054] In the above configuration, except for the bottom and top two layers of the plurality of laminates 3, the positive electrode current collector 4 overlaps at a contact portion 41 in contact with each of the two positive electrode layers 31 that overlap between the two stacked first and second laminates. Furthermore, except for the bottom two layers and the top laminate 3 of the plurality of laminates 3, the negative electrode current collector 6 overlaps at a contact portion 61 between the two negative electrode layers 32 that overlap between the two stacked second and third laminates.

[0055] In this way, the positive electrode current collector 4 is electrically connected at the contact portion 41, and therefore the positive electrode current collector 4 can be treated as a single current collector from the viewpoint of electrical conductivity. The negative electrode current collector 6 is electrically connected at the contact portion 61, and therefore the negative electrode current collector 6 can be treated as a single current collector from the viewpoint of electrical conductivity. Therefore, it is not necessary to connect multiple positive electrode current collectors 4 provided as a unit in contact with the two positive electrode layers 31 of two stacked laminates 3. Similarly, it is not necessary to connect multiple negative electrode current collectors 6 provided as a unit in contact with the two second electrode layers of two stacked laminates.

[0056] Therefore, no connection such as welding occurs between the positive electrode current collector 4 and the negative electrode current collector 6. This makes it possible to prevent a decrease in energy density between the positive electrode current collector 4 and the negative electrode current collector 6. In general, the energy density of a battery is the energy that can be extracted per unit mass or per unit volume of the battery. If a connection such as that described above occurs between the positive electrode current collector and the negative electrode current collector, the volume of the connection increases, and therefore the energy density per volume decreases compared to the configuration of this embodiment in which no such connection exists.

[0057] Although the negative electrode current collector 6 is folded back along the side surface 3b opposite to the side surface 3a, it may also be folded back along another side surface, for example, along the side surface (opposite side surface) of the second and third laminates opposite to the side where the tabs 4a and 6a are provided. Furthermore, the positive electrode current collector 4 is folded back along the side surface 3a opposite to the side surface 3b, but it may also be folded back along another side surface, the opposite side surface.

[0058] Furthermore, one positive electrode current collector 4 contacts two positive electrode layers 31, and one negative electrode current collector 6 contacts two negative electrode layers 32. This prevents the positive electrode current collector 4 and the negative electrode current collector 6 from becoming too large in size as components, and prevents the number of the positive electrode current collectors 4 and the negative electrode current collectors 6 from becoming too large. This improves the workability of arranging the positive electrode current collectors 4 and the negative electrode current collectors 6 between the laminates 3 in addition to stacking the laminates 3.

[0059] Furthermore, the tab 4a can be provided at any location on the positive electrode current collector 4 as long as it can protrude from the contact portion 41 to the side of the positive electrode layer 31. Furthermore, the tab 6a can be provided at any location on the negative electrode current collector 6 as long as it can protrude from the contact portion 61 to the side of the negative electrode layer 32. Therefore, the tabs 4a and 6a can be disposed at desired positions in the height direction in which the laminate 3 is stacked.

[0060] [Embodiment 2] Another embodiment of the present invention will be described below. For ease of explanation, components having the same functions as those described in the above embodiment will be denoted by the same reference numerals, and their description will not be repeated.

[0061] 1 is a plan view showing the configuration of an all-solid-state battery 102 according to this embodiment. Fig. 6 is a diagram showing the structure of a battery unit 1A included in the all-solid-state battery 102 according to this embodiment.

[0062] As shown in FIG. 1 , the all-solid-state battery 102 includes a battery unit 1A instead of the battery unit 1 of the all-solid-state battery 101 described above, and also includes a laminated exterior body 2. The battery unit 1A is enclosed in the laminated exterior body 2. As also shown in FIG. 6 , the battery unit 1A includes, like the battery unit 1, a plurality of laminated bodies 3, a positive electrode current collector 5, sealants 7 and 8, and an insulating part 10. Furthermore, the battery unit 1A includes a positive electrode current collector 4A (first current collector) and a negative electrode current collector 6A (second current collector) instead of the positive electrode current collector 4 and the negative electrode current collector 6 of the battery unit 1. The battery unit 1A is configured by connecting a plurality of laminated bodies 3 in parallel, each of which can function as a battery on its own.

[0063] <Details of the Positive Electrode Current Collector and the Negative Electrode Current Collector> The positive electrode current collector 4A and the negative electrode current collector 6A each have a multiple-fold structure and are formed as a single piece. Specifically, the positive electrode current collector 4A is formed in a long strip shape and has multiple contact portions 41A and multiple folded portions 42A. The negative electrode current collector 6A is formed in a long strip shape and has multiple contact portions 61A and multiple folded portions 62A.

[0064] The contact portion 41A is shaped to be folded between two opposing positive electrode layers 31 so as to contact the surfaces of the positive electrode layers 31 of the two stacked laminates 3. However, the lowermost contact portion 41A of the positive electrode current collector 4A is not folded back because there is no laminate 3 therebelow. In addition, the uppermost contact portion 41A of the positive electrode current collector 4A is not folded back.

[0065] The folded portion 42A is provided between the two contact portions 41 A. The folded portion 42A is a portion where the positive electrode current collector 4A is folded along the side surfaces 3 a of the two laminates 3 .

[0066] In this way, by folding the positive electrode collector 4A at the folding portion 42A, the contact portion 41A comes into contact with the positive electrode layer 31 provided on the lower one of the two laminates 3 (first laminate) and the positive electrode layer 31 provided on the laminate 3 (second laminate) stacked on top of that laminate 3.

[0067] The contact portion 61A is shaped to be folded between the two opposing negative electrode layers 32 so as to contact the surfaces of the respective negative electrode layers 32 in the two stacked laminates 3. However, the lowermost contact portion 61A in the negative electrode current collector 6A is not folded back. In addition, the uppermost contact portion 61A in the negative electrode current collector 6A is not folded back because there is no laminate 3 above it.

[0068] The folded portion 62A is provided between the two contact portions 61 A. The folded portion 62A is a portion where the negative electrode current collector 6A is folded along the side surfaces 3 b of the two laminates 3 .

[0069] In this way, by folding the negative electrode current collector 6A at the folding portion 62A, the contact portion 61A comes into contact with the negative electrode layer 32 included in the lower one of the two laminates 3 (the second laminate) and the negative electrode layer 32 included in the laminate 3 (the third laminate) stacked on top of the lower one. In FIG. 6 , the first laminate corresponds to the bottommost laminate 3, the second laminate corresponds to the laminate 3 stacked on the first laminate, and the third laminate corresponds to the laminate 3 stacked on the second laminate. The third laminate also serves as the first laminate. In this way, the first to third laminates are repeatedly stacked.

[0070] With the above-described structure, between the two stacked laminates 3, the two opposing positive electrode layers 31 are electrically connected via the contact portion 41A of the positive electrode current collector 4A, and the two opposing negative electrode layers 32 are electrically connected via the contact portion 61A of the negative electrode current collector 6A. Furthermore, the lower positive electrode layer 31 of the lowermost laminate 3 contacts the lower contact portion 41A of the lowermost positive electrode current collector 4A. The upper negative electrode layer 32 of the uppermost laminate 3 contacts the upper contact portion 61A of the uppermost negative electrode current collector 6A.

[0071] As a result, in the plurality of stacks 3, the positive electrode layers 31 are electrically connected to each other by the single positive electrode current collector 4A, and the negative electrode layers 32 are electrically connected to each other by the single negative electrode current collector 6A. Therefore, the stacks 3 in the battery unit 1 are connected in parallel.

[0072] A tab 4a is provided on the lowest contact portion 41A of the positive electrode current collector 4A. A tab 6a is provided on the lowest contact portion 61A of the negative electrode current collector 6A. The positions of the tabs 4a, 6a on the positive electrode current collector 4A and the negative electrode current collector 6A are not limited to those described above, and they may be provided on either of the contact portions 41A, 61A.

[0073] <Manufacturing of All-Solid-State Battery> The manufacturing (manufacturing method) of the all-solid-state battery 102 configured as above will be described. Fig. 7 is a diagram showing the manufacturing process of the all-solid-state battery 102. Fig. 8 is a diagram showing the manufacturing process of the all-solid-state battery 102 subsequent to the manufacturing process shown in Fig. 7.

[0074] 7, first, the positive electrode current collector 4A is placed in an unfolded state on a workbench (not shown), and the insulating part 10 is placed on one end of the positive electrode current collector 4A where the tab 4a is provided (step S21). In step S21, the sealant 7 is attached to the tab 4a.

[0075] Next, the stack 3 (first stage) is placed inside the insulating portion 10 of the positive electrode current collector 4A with the negative electrode layer 32 facing up, i.e., with the positive electrode layer 31 facing down (step S22).

[0076] Next, the negative electrode current collector 6A is placed in an unfolded state on the laminate 3 and the insulating portion 10, and the insulating portion 10 is placed on one end of the unfolded negative electrode current collector 6A where the tab 6a is provided (step S23). In step S23, the negative electrode current collector 6A is placed so that the tab 6a is close to the tab 4a, and the sealant 8 is attached to the tab 6a. In addition, the portion of the negative electrode current collector 6A where the insulating portion 10 is not provided is unfolded on the opposite side to the portion of the positive electrode current collector 4A where the insulating portion 10 is not provided.

[0077] Next, the stack 3 (second stage) is placed inside the insulating portion 10 on the negative electrode current collector 6A with the positive electrode layer 31 facing up, i.e., with the negative electrode layer 32 facing down (step S24).

[0078] Then, the unfolded portion of the positive electrode current collector 4A is folded back so as to cover the laminate 3 arranged in step S24 (step S25). In step S25, the folded back portion of the positive electrode current collector 4A is brought into contact with the surface of the laminate 3, thereby forming a contact portion 41A. Furthermore, in step S25, the folded back portion of the positive electrode current collector 4A is folded back in the direction opposite to the folding direction. This forms a contact portion 41A that overlaps the contact portion 41A, and an insulating portion 10 is arranged on the contact portion 41A (step S26).

[0079] Next, the stack 3 (third stage) is placed inside the insulating portion 10 on the positive electrode current collector 4A with the negative electrode layer 32 facing up, i.e., with the positive electrode layer 31 facing down (step S27).

[0080] Then, the unfolded portion of the negative electrode current collector 6A is folded back so as to cover the laminate 3 arranged in step S27 (step S28). In step S28, the folded back portion of the negative electrode current collector 6A is brought into contact with the surface of the laminate 3, thereby forming the contact portion 61A.

[0081] Then, in step S28, the folded portion of the negative electrode current collector 6 is folded in the direction opposite to the folded direction. As a result, a contact portion 61A that overlaps the contact portion 61A is formed, and the insulating portion 10 is placed on the contact portion 61A, resulting in the same state as step S23 in plan view. Note that, for convenience, this state will be referred to as step S23 here.

[0082] Thereafter, steps S24 to S28 are performed again to stack the fourth and fifth stacks 3. Furthermore, steps S23 to S25 are performed again to stack the sixth stack 3.

[0083] 8 , a positive electrode current collector 5 is placed on the positive electrode current collector 4A formed in step S25 (step S29). After that, an insulating part 10 is placed on the positive electrode current collector 5, and the stack 3 (seventh layer) is placed inside the insulating part 10 on the positive electrode current collector 5 with the negative electrode layer 32 facing up, i.e., with the positive electrode layer 31 facing down (step S30). Then, the other end of the unfolded negative electrode current collector 6A is folded back so as to cover the stack 3 placed in step S30 (step S11), thereby completing the battery unit 1A.

[0084] Finally, the completed battery unit 1A is sealed with the laminated outer casing 2 in the same manner as the battery unit 1 described above is sealed with the laminated outer casing 2.

[0085] In the above manufacturing process, steps S22, S24, S27, and S30 are performed to stack the first to seventh stacks 3 so that the positive electrode layers 31 and the negative electrode layers 32 overlap each other (stacking step). Steps S21 and S26 are performed to place the positive electrode collector 4A below the bottommost positive electrode layer 31 of the stack 3 before the stacking step (first placement step). Step S23 is performed to place the negative electrode collector 6A on the topmost positive electrode layer 31 of the stack 3 after the stacking step (second placement step). Step S25 is performed to fold the positive electrode collector 4A over the topmost positive electrode layer 31 of the stack 3 stacked on top of the stack 3 in the stacking step by folding it along the side surfaces 3a of the two stacks 3 (first folding step). In addition, in steps S28 and S31, the negative electrode current collector 6A is folded back along the side surface 3b of the two laminates 3 and placed on top of the uppermost negative electrode layer 32 of the laminate 3 that was stacked on top of the two laminates 3 in the stacking process (second folding process).

[0086] Effect of the embodiment As described above, the all-solid-state battery 102 according to the present embodiment includes a plurality of laminates 3, a positive electrode current collector 4A, and a negative electrode current collector 6A. The positive electrode current collector 4A and the negative electrode current collector 6A each have a multiple-fold structure and are formed as a single body.

[0087] As a result, no connection parts such as welding are formed between the positive electrode current collector 4A and the negative electrode current collector 6A. This makes it possible to prevent a decrease in energy density in the positive electrode current collector 4A and the negative electrode current collector 6A. Furthermore, the positive electrode current collector 4A and the negative electrode current collector 6A, each having a multiple folded structure, can be treated as a single component. This reduces the number of components in the all-solid-state battery 102.

[0088] [Summary] As described above, the all-solid-state battery according to the first aspect of the present invention includes a plurality of laminates each including a first electrode layer, a second electrode layer having a polarity opposite to that of the first electrode layer, and a solid electrolyte layer interposed between the first electrode layer and the second electrode layer, a first current collector provided in contact with the first electrode layer, and a second current collector provided in contact with the second electrode layer, wherein the plurality of laminates are stacked such that the first electrode layers and the second electrode layers of each laminate face each other, and the first current collector is disposed between the first and second current collectors of the plurality of laminates. and the first electrode layer of a second stack of the plurality of stacks stacked on the first stack, and the second current collector is folded back along second side surfaces of the second and third stacks, on the side opposite to the first side surface, so as to contact the second electrode layer of the second stack of the plurality of stacks and the second electrode layer of a third stack of the plurality of stacks stacked on the second stack.

[0089] In the above configuration, a first current collector in contact with each of the first electrode layers overlaps between two first electrode layers that overlap between two stacked first and second stacks, excluding the bottom two and top two stacks among the plurality of stacks. Also, a second current collector in contact with each of the second electrode layers overlaps between two second electrode layers that overlap between two stacked second and third stacks, excluding the bottom two and top stacks among the plurality of stacks.

[0090] In this way, the first current collector is electrically conductive at the overlapping portion thereof, and therefore the first current collector can be treated as a single current collector from the viewpoint of electrical conductivity. The second current collector is electrically conductive at the overlapping portion thereof, and therefore the second current collector can be treated as a single current collector from the viewpoint of electrical conductivity. Therefore, even if a plurality of first current collectors are provided as a unit structure that contacts the two first electrode layers of the two stacked laminates, there is no need to connect them. Similarly, even if a plurality of second current collectors are provided as a unit structure that contacts the two second electrode layers of the two stacked laminates, there is no need to connect them.

[0091] Therefore, no connection such as welding is formed between the first current collector and the second current collector, and therefore, a decrease in energy density in the first current collector and the second current collector can be made less likely to occur.

[0092] The all-solid-state battery according to Aspect 2 of the present invention may be the same as Aspect 1, wherein the first current collector is provided in a plurality of units, each unit being in contact with two of the first electrode layers in the first and second laminates, and the second current collector is provided in a plurality of units, each unit being in contact with two of the second electrode layers in the second and third laminates.

[0093] In the above configuration, one first current collector contacts two first electrode layers, and one second current collector contacts two second electrode layers. This prevents the first current collector and the second current collector from becoming too large as components, and prevents the number of the first current collectors from becoming too large. This improves the workability of arranging the first current collector and the second current collector between the stacks in conjunction with stacking the stacks.

[0094] In the all-solid-state battery according to Aspect 3 of the present invention, in the above-mentioned Aspect 1, the first current collector and the second current collector may each have a multi-fold structure and be formed as a single piece.

[0095] According to the above configuration, the first current collector and the second current collector each having a multiple folded structure can be treated as a single component, thereby reducing the number of components in the all-solid-state battery.

[0096] The all-solid-state battery according to Aspect 4 of the present invention is the all-solid-state battery of any one of Aspects 1 to 3, wherein the first current collector has a first tab that protrudes laterally from a portion that contacts the first electrode layer toward the first electrode layer, and the second current collector has a second tab that protrudes laterally from a portion that contacts the second electrode layer toward the second electrode layer.

[0097] According to the above configuration, the first tab can be provided at any location on the first current collector as long as it can protrude laterally from the portion in contact with the first electrode layer. Also, the second tab can be provided at any location on the second current collector as long as it can protrude laterally from the portion in contact with the second electrode layer. Therefore, the first tab and the second tab can be arranged at desired positions in the height direction of the stack.

[0098] A manufacturing method of an all-solid-state battery according to a fifth aspect of the present invention is a manufacturing method of an all-solid-state battery including: a laminate in which a first electrode layer, a second electrode layer having a polarity opposite to that of the first electrode layer, and a solid electrolyte layer interposed between the first electrode layer and the second electrode layer are stacked; a first current collector provided so as to contact the first electrode layer; and a second current collector provided so as to contact the second electrode layer, the manufacturing method including the steps of: stacking a plurality of the laminates such that the first electrode layers overlap each other and the second electrode layers overlap each other; and arranging the first current collector below the first electrode layer, which is the lowest layer in the laminate before being arranged in the stacking step. a second arranging step of arranging the second current collector on the second electrode layer that is the uppermost layer of the laminate after being arranged in the stacking step; a first folding step of folding back the first current collector onto the first electrode layer that is the uppermost layer of the laminate that was stacked on the laminate in the stacking step, along a first side surface of the two laminates; and a second folding step of folding back the second current collector onto the second electrode layer that is the uppermost layer of the laminate that was stacked on the two laminates in the stacking step, along a second side surface of the two laminates that is on the side opposite to the first side surface.

[0099] According to the above method, a first current collector can be placed between the topmost first electrode layer and the bottommost first electrode layer, overlapping between the two stacked laminates, excluding the bottom and top two layers of the laminate. Also, a second current collector can be placed between the topmost second electrode layer and the bottommost second electrode layer, overlapping between the two stacked laminates, excluding the bottom two layers and the top laminate, contacting the respective second electrode layers.

[0100] Therefore, similar to the above-described all-solid-state battery, a decrease in energy density can be made less likely to occur in the first current collector and the second current collector.

[0101] [Additional Notes] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Furthermore, the technical scope of the present invention also includes configurations obtained by appropriately combining the technical means disclosed in each embodiment.

[0102] 3 Laminate (first to third laminate) 3a Side (first side) 3b Side (second side) 4, 4A Positive electrode current collector 6, 6A Negative electrode current collector 4a Tab (first tab) 6b Tab (second tab) 31 Positive electrode layer (first electrode layer) 32 Negative electrode layer (second electrode layer) 101, 102 All-solid-state battery

Claims

1. A method for manufacturing a battery comprising: a plurality of laminates each including a first electrode layer, a second electrode layer having a polarity opposite to that of the first electrode layer, and a solid electrolyte layer interposed between the first electrode layer and the second electrode layer; a first current collector provided so as to contact the first electrode layer; and a second current collector provided so as to contact the second electrode layer; wherein the plurality of laminates are stacked such that the first electrode layers and the second electrode layers of each laminate face each other; and the first current collector is folded back along first side surfaces of the first and second laminates so as to contact the first electrode layer of a first laminate of the plurality of laminates and the first electrode layer of a second laminate of the plurality of laminates stacked on the first laminate; the second current collector is folded back along second side surfaces of the second and third stacks on a side different from the first side surface so as to contact the second electrode layer included in the second stack of the plurality of stacks and the second electrode layer included in a third stack of the plurality of stacks stacked on the second stack.

2. The all-solid-state battery according to claim 1, wherein a plurality of the first current collectors are provided, each of which is configured to contact two of the first electrode layers in the first and second laminates, and a plurality of the second current collectors are provided, each of which is configured to contact two of the second electrode layers in the second and third laminates.

3. The all-solid-state battery according to claim 1, wherein the first current collector and the second current collector have a structure in which they are folded over in multiple turns, and are each formed as a single piece.

4. The all-solid-state battery according to any one of claims 1 to 3, wherein the first current collector has a first tab that protrudes laterally from the first electrode layer from a portion that contacts the first electrode layer, and the second current collector has a second tab that protrudes laterally from the second electrode layer from a portion that contacts the second electrode layer.

5. A method for manufacturing an all-solid-state battery comprising: a laminate including a first electrode layer, a second electrode layer having a polarity opposite to that of the first electrode layer, and a solid electrolyte layer interposed between the first electrode layer and the second electrode layer; a first current collector provided so as to contact the first electrode layer; and a second current collector provided so as to contact the second electrode layer, the method comprising: a laminating step of laminating a plurality of the laminates such that the first electrode layers and the second electrode layers overlap; a first arranging step of arranging the first current collector below the first electrode layer that is the lowest layer in the laminate before being arranged in the laminating step; a second arranging step of arranging the second current collector above the second electrode layer that is the highest layer in the laminate after being arranged in the laminating step; and a first folding step of folding the first current collector over the first electrode layer that is the highest layer in the laminate that was arranged on the laminate in the laminating step, along a first side surface of the two laminates. a second folding step of folding the second current collector back onto the second electrode layer that is an uppermost layer of the stacked body that is stacked on the two stacked bodies in the stacking step, along second side surfaces of the two stacked bodies that are on a side different from the first side surface.

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