Secondary battery and method for manufacturing same

Abstract

Provided is a secondary battery that can be produced efficiently and in which a short circuit between a positive electrode side collector member and a negative electrode side collector member is unlikely to occur.　A secondary battery 1 comprises: an electric power storage element 2 that has a positive electrode layer 6, a negative electrode layer 7, and a solid electrolyte layer 5; a positive-electrode-side current collector layer 3; and a negative-electrode-side current collector layer 4. In a plan view, outer peripheral edges 6a, 7a of the positive electrode layer 6 and the negative electrode layer 7 are arranged inwardly of outer peripheral edges 5a of the solid electrolyte layer 5. In a plan view, the positive-electrode-side current collector layer 3 includes a positive-electrode-side current collector body 8 that is disposed inwardly of the outer peripheral edges 5a of the solid electrolyte layer 5, and a positive-electrode-side current collector protrusion 9 that protrudes from an end surface 8b of the positive-electrode-side current collector body 8. The positive-electrode-side current collector protrusion 9 has a positive-electrode-side current collector protrusion end surface 9a that is provided so as to be aligned with an end surface 5b of the solid electrolyte layer 5. In a plan view, the negative-electrode-side current collector layer 4 includes: a negative-electrode-side current collector body 10 that is disposed inwardly of the outer peripheral edges 5a of the solid electrolyte layer 5, and a negative-electrode-side current collector protrusion 11 that protrudes from an end surface 10b of the negative-electrode-side current collector body 10. The negative-electrode-side current collector protrusion 11 has a negative-electrode-side current collector protrusion end surface 11a that is provided so as to be aligned with the end surface 5b of the solid electrolyte layer 5. The positive-electrode-side current collector protrusion end surface 9a and the negative-electrode-side current collector protrusion end surface 11a do not overlap in a plan view.

Description

Secondary battery and manufacturing method thereof

[0001] The present invention relates to a secondary battery such as an all-solid-state secondary battery or an electrolyte secondary battery, and a method for manufacturing the secondary battery.

[0002] Lithium-ion secondary batteries are essential for mobile devices, electric vehicles, and other devices, and have established themselves as high-capacity, lightweight power sources. However, current lithium-ion secondary batteries primarily use flammable organic electrolytes, raising concerns about the risk of fire. To address this issue, development is underway on all-solid-state secondary batteries, such as all-solid-state lithium-ion secondary batteries and all-solid-state sodium-ion secondary batteries, which use solid electrolytes instead of organic electrolytes.

[0003] Patent Document 1 listed below discloses an all-solid-state battery including a battery stack formed by stacking two or more battery units each including a positive electrode including a positive electrode-side current collector layer and a positive electrode layer, a negative electrode including a negative electrode-side current collector layer and a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer.

[0004] Japanese Patent Application Laid-Open No. 2020-119633

[0005] However, when stacking units of energy storage elements each having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer, as in Patent Document 1, a short circuit may occur due to contact between a positive electrode current collector layer, a positive electrode tab lead, or another positive electrode current collector layer and a negative electrode current collector layer, a negative electrode tab lead, or another negative electrode current collector layer. Therefore, when stacking units of energy storage elements, a device such as an alignment camera may be used to position the energy storage elements and the current collectors to prevent short circuits due to misalignment of the current collectors. However, devices such as alignment cameras are expensive, and stacking the energy storage elements and current collectors after positioning them takes time, resulting in reduced productivity of the resulting secondary battery. Furthermore, a short circuit may occur due to misalignment of the current collectors after stacking the energy storage elements and current collectors.

[0006] An object of the present invention is to provide a secondary battery that is highly productive and that is less likely to cause a short circuit between a positive electrode current collector and a negative electrode current collector, and a method for manufacturing such a secondary battery.

[0007] Hereinafter, various aspects of a secondary battery that solves the above problems and a method for manufacturing the secondary battery will be described.

[0008] A secondary battery according to a first aspect of the present invention is an all-solid-state secondary battery comprising an energy storage element having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer, a positive electrode-side current collector layer, and a negative electrode-side current collector layer, wherein, in a plan view, outer peripheral edges of the positive electrode layer and the negative electrode layer are located inside the outer peripheral edge of the solid electrolyte layer, and the positive electrode-side current collector layer is located inside the outer peripheral edge of the solid electrolyte layer, and the secondary battery comprises the positive electrode-side current collector main body portion and a positive electrode-side current collector protrusion portion protruding from an end face of the positive electrode-side current collector main body portion, and the positive electrode-side current collector protrusion portion is and has a positive electrode-side current collector protruding end face that is aligned with an end face of the solid electrolyte layer, and in plan view, the negative electrode-side current collector layer comprises the negative electrode-side current collector main body portion that is positioned inside the outer circumferential edge of the solid electrolyte layer, and a negative electrode-side current collector protruding portion that protrudes from the end face of the negative electrode-side current collector main body portion, and the negative electrode-side current collector protruding end face is aligned with the end face of the solid electrolyte layer, and in plan view, the positive electrode-side current collector protruding end face and the negative electrode-side current collector protruding end face do not have an overlapping portion.

[0009] A secondary battery according to Aspect 2 may be the same as Aspect 1, in which a plurality of the positive electrode collector protruding portions and a plurality of the negative electrode collector protruding portions are provided.

[0010] A secondary battery according to Aspect 3 is the same as Aspect 1 or Aspect 2, and may further include tab leads connected to the positive electrode current collector protruding portion and the negative electrode current collector protruding portion, respectively.

[0011] In the secondary battery according to Aspect 4, in any one of Aspects 1 to 3, it is preferable that the outer peripheral edges of the positive electrode side current collector body portion and the negative electrode side current collector body portion are not located inside the outer peripheral edges of the positive electrode layer and the negative electrode layer.

[0012] A secondary battery according to Aspect 5 is the secondary battery according to any one of Aspects 1 to 4, and it is preferable that, in plan view, the positive electrode side current collector layer includes a pair of the positive electrode side current collector protrusions that are provided in positions facing each other, and the negative electrode side current collector layer includes a pair of the negative electrode side current collector protrusions that are provided in positions facing each other,

[0013] A secondary battery according to Aspect 6 is the secondary battery of Aspect 5, and it is preferable that, in plan view, the positive electrode side current collector main body and the negative electrode side current collector main body have a substantially rectangular shape, the positive electrode side current collector layer includes a pair of positive electrode side current collector protrusions provided at opposing corners of the positive electrode side current collector main body, and the negative electrode side current collector layer includes a pair of negative electrode side current collector protrusions provided at opposing corners of the negative electrode side current collector main body, in plan view.

[0014] A secondary battery according to Aspect 7 is the secondary battery according to any one of Aspects 1 to 5, and in plan view, the positive electrode side current collector body portion and the negative electrode side current collector body portion may have a substantially circular shape.

[0015] A secondary battery according to Aspect 8 is any one of Aspects 1 to 7, wherein the positive electrode side current collector layer has a connection end face connecting an end face of the positive electrode side current collector main body portion and the positive electrode side current collector protruding end face, and the negative electrode side current collector layer has a connection end face connecting an end face of the negative electrode side current collector main body portion and the negative electrode side current collector protruding end face.

[0016] A secondary battery according to Aspect 9 is any one of Aspects 1 to 8, and is configured by stacking a plurality of units of the energy storage element. In the energy storage elements adjacent to each other in the stacking direction, the positive electrode layers or the negative electrode layers are preferably arranged to face each other, and the positive electrode-side current collector layer is arranged between the positive electrode layers, and the negative electrode-side current collector layer is arranged between the negative electrode layers.

[0017] A method for manufacturing a secondary battery according to Aspect 10 of the present invention is a method for manufacturing a secondary battery according to any one of Aspects 1 to 9, comprising the steps of: arranging a positive electrode-side current collector positioning member at a position where the positive electrode-side current collector protruding end face is to be arranged, and arranging a negative electrode-side current collector positioning member at a position where the negative electrode-side current collector protruding end face is to be arranged; arranging the positive electrode-side current collector layer so that the positive electrode-side current collector protruding end face is aligned with the position of the positive electrode-side current collector positioning member; arranging the energy storage element so that the end face of the solid electrolyte layer is aligned with the positions of the positive electrode-side current collector positioning member and the negative electrode-side positioning member; and arranging the negative electrode-side current collector layer so that the negative electrode-side current collector protruding end face is aligned with the position of the negative electrode-side current collector positioning member.

[0018] A method for manufacturing a secondary battery according to Aspect 11 of the present invention is a method for manufacturing a secondary battery according to any one of Aspects 1 to 9, comprising the steps of: preparing a case member that houses the energy storage element, the positive electrode-side current collector layer, and the negative electrode-side current collector layer; arranging the positive electrode-side current collector layer on an inner wall surface of the case member so that a protruding end face of the positive electrode-side current collector is aligned with the inner wall surface of the case member; arranging the energy storage element on an inner wall surface of the case member so that an end face of the solid electrolyte layer is aligned with the inner wall surface of the case member; and arranging the negative electrode-side current collector layer on an inner wall surface of the case member so that a protruding end face of the negative electrode-side current collector is aligned with the inner wall surface of the case member.

[0019] A secondary battery according to a twelfth aspect of the present invention is a liquid electrolyte battery comprising an electric storage element having a positive electrode layer, a negative electrode layer, and a separator, a positive electrode-side current collector layer, and a negative electrode-side current collector layer, wherein, in a plan view, outer peripheral edges of the positive electrode layer and the negative electrode layer are located inside the outer peripheral edge of the separator, and the positive electrode-side current collector layer is located inside the outer peripheral edge of the separator, and the secondary battery comprises the positive electrode-side current collector main body portion and a positive electrode-side current collector protrusion portion protruding from an end face of the positive electrode-side current collector main body portion, and the positive electrode-side current collector protrusion portion has a positive electrode-side current collector protruding end face that is aligned with the end face of the separator, and in plan view, the negative electrode-side current collector layer comprises the negative electrode-side current collector main body portion that is positioned inside the outer peripheral edge of the separator, and a negative electrode-side current collector protruding portion that protrudes from the end face of the negative electrode-side current collector main body portion, and the negative electrode-side current collector protruding end face has a negative electrode-side current collector protruding end face that is aligned with the end face of the separator, and in plan view, the positive electrode-side current collector protruding end face and the negative electrode-side current collector protruding end face do not have an overlapping portion.

[0020] According to the present invention, it is possible to provide a secondary battery that is highly productive and that is less likely to cause a short circuit between the positive electrode side current collecting member and the negative electrode side current collecting member, and a method for manufacturing the secondary battery.

[0021] FIG. 1 is a schematic plan view showing a secondary battery according to a first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing a portion along line A-A in FIG. 1. FIG. 3 is a schematic plan view showing a positive electrode side current collector layer constituting the secondary battery according to the first embodiment of the present invention. FIG. 4 is a schematic plan view showing a secondary battery according to a second embodiment of the present invention. FIG. 5 is a schematic plan view showing a positive electrode side current collector layer constituting the secondary battery according to the second embodiment of the present invention. FIG. 6 is a schematic plan view showing a secondary battery according to a third embodiment of the present invention. FIG. 7 is a schematic plan view showing a positive electrode side current collector layer constituting the secondary battery according to the third embodiment of the present invention. FIG. 8 is a schematic plan view showing a secondary battery according to a fourth embodiment of the present invention. FIG. 9 is a schematic plan view showing a positive electrode side current collector layer constituting the secondary battery according to the fourth embodiment of the present invention. FIG. 10 is a schematic plan view showing a secondary battery according to a fifth embodiment of the present invention. FIG. 11 is a schematic cross-sectional view showing a portion along line B-B in FIG. 10. Fig. 12 is a schematic plan view showing a positive electrode side current collector layer constituting a secondary battery according to a fifth embodiment of the present invention. Fig. 13 is a schematic cross-sectional view showing a secondary battery according to a sixth embodiment of the present invention. Fig. 14 is a schematic plan view showing a secondary battery according to a seventh embodiment of the present invention. Fig. 15 is a schematic cross-sectional view showing a portion along line CC in Fig. 14. Fig. 16 is a schematic plan view showing a secondary battery of Comparative Example 1. Fig. 17 is a schematic cross-sectional view showing a portion along line DD in Fig. 16. Fig. 18 is a schematic plan view showing a secondary battery of Comparative Example 2.

[0022] Preferred embodiments of the present invention will be described below. However, the following embodiments are merely examples, and the present invention is not limited to the following embodiments. In addition, in each drawing, components having substantially the same functions may be referred to by the same reference numerals.

[0023] [First embodiment] Fig. 1 is a schematic plan view showing a secondary battery according to a first embodiment of the present invention. Fig. 2 is a schematic cross-sectional view showing a portion along line AA in Fig. 1. Fig. 3 is a schematic plan view showing a positive electrode side current collector layer constituting the secondary battery according to the first embodiment of the present invention.

[0024] As shown in Figures 1 and 2, the secondary battery 1 includes an energy storage element 2, a positive electrode-side current collector layer 3, and a negative electrode-side current collector layer 4. In this embodiment, the secondary battery 1 is an all-solid-state secondary battery. Examples of all-solid-state secondary batteries include all-solid-state lithium-ion secondary batteries, all-solid-state sodium-ion secondary batteries, and all-solid-state magnesium-ion secondary batteries. While an all-solid-state sodium-ion secondary battery will be described below as an example, the following embodiment is applicable to all-solid-state secondary batteries in general.

[0025] The secondary battery 1 of this embodiment has a plurality of energy storage elements 2, each of which is a single unit. Although two energy storage elements 2 are illustrated in Fig. 2, the number of energy storage elements 2 is not particularly limited. The number of energy storage elements 2 can be, for example, 1 or more and 50 or less.

[0026] As shown in FIG. 2 , in the secondary battery 1 of this embodiment, a positive electrode-side current collector layer 3, an energy storage element 2, a negative electrode-side current collector layer 4, an energy storage element 2, and a positive electrode-side current collector layer 3 are stacked in this order. In this embodiment, two energy storage elements 2 are arranged so as to share the negative electrode-side current collector layer 4. Therefore, in both of the two energy storage elements 2, the negative electrode layers 7 are arranged on the negative electrode-side current collector layer 4 side. In this manner, it is desirable that adjacent energy storage elements 2 in the stacking direction are arranged so as to share a current collector layer. For example, when another energy storage element 2 is stacked on the secondary battery 1 of this embodiment, it is desirable that adjacent energy storage elements 2 in the stacking direction are arranged so as to share the positive electrode-side current collector layer 3, and that the positive electrode layer 6 is arranged on the positive electrode-side current collector layer 3 side.

[0027] The energy storage element 2 has a solid electrolyte layer 5, a positive electrode layer 6, and a negative electrode layer 7. In the lower energy storage element 2 shown in FIG. 2 , the positive electrode layer 6, the solid electrolyte layer 5, and the negative electrode layer 7 are stacked in this order from the bottom. In the upper energy storage element 2 shown in FIG. 2 , the negative electrode layer 7, the solid electrolyte layer 5, and the positive electrode layer 6 are stacked in this order from the bottom. The positive electrode layer 6 is provided so as to be in contact with the positive electrode-side current collector layer 3. The negative electrode layer 7 is provided so as to be in contact with the negative electrode-side current collector layer 4.

[0028] As shown in the plan view of FIG. 1 , the positive electrode side current collector layer 3 has a positive electrode side current collector body portion 8 and a positive electrode side current collector protrusion portion 9. The outer peripheral edge 8a of the positive electrode side current collector body portion 8 is located inside the outer peripheral edge 5a of the solid electrolyte layer 5. The outer peripheral edge 8a of the positive electrode side current collector body portion 8 is located outside the outer peripheral edge 6a of the positive electrode layer 6. The outer peripheral edge 8a of the positive electrode side current collector body portion 8 is also located at the same position as the outer peripheral edge 7a of the negative electrode layer 7. As described above, the outer peripheral edge 8a of the positive electrode side current collector body portion 8 is located inside the outer peripheral edge 5a of the solid electrolyte layer 5, but is preferably not located inside the outer peripheral edge 6a of the positive electrode layer 6 or the outer peripheral edge 7a of the negative electrode layer 7. In addition, it is preferable that the positive electrode side current collector body portion 8 and the positive electrode layer 6 have similar shapes in a plan view.

[0029] The positive electrode side current collector protrusions 9 are protrusions that protrude from the end surface 8b of the positive electrode side current collector main body 8. In this embodiment, the planar shape of the positive electrode side current collector main body 8 is approximately rectangular, and a pair of positive electrode side current collector protrusions 9 are provided at opposing corners 8c of the positive electrode side current collector main body 8. As shown in FIG. 3 , the positive electrode side current collector protrusions 9 are connected to two sides 8a1, 8a2 of the outer circumferential edge 8a of the positive electrode side current collector main body 8 at the corners 8c of the positive electrode side current collector main body 8. In the present invention, it is sufficient that the positive electrode side current collector layer 3 has at least one positive electrode side current collector protrusion 9.

[0030] The positive electrode current collector protruding portion 9 has a positive electrode current collector protruding end surface 9a that is aligned with the end surface 5b of the solid electrolyte layer 5. In this embodiment, a connecting end surface 9b is provided that connects the end surface 8b of the positive electrode current collector main body portion 8 and the positive electrode current collector protruding end surface 9a. The angle (e.g., θ in FIG. 3 ) between the extension direction of the end surface 8b of the positive electrode current collector main body portion 8 and the extension direction of the connecting end surface 9b is preferably not a right angle but an acute angle. In this case, the connecting end surface 9b extends obliquely with respect to the extension direction of the end surface 8b of the positive electrode current collector main body portion 8, which makes it less likely for the positive electrode current collector protruding portion 9 to get caught or bend during stacking, thereby making the stacking operation faster and easier. Furthermore, since the connection portion between the positive electrode collector protruding portion 9 and the positive electrode collector main body portion 8 can be made wider, bending of the positive electrode collector protruding portion 9 during stacking is less likely to occur. In this embodiment, a tab lead 13 is connected to the positive electrode collector protruding portion 9 (for example, a tab portion is formed on one of the protruding portions, and a nickel or aluminum lead is welded to a bundle of these tab portions, and the lead portion is taken out to the outside of the laminate exterior body. In the case of a prismatic battery using a metal can, the lead is welded to the inside of the exterior can or the inside of the sealing body and then sealed).

[0031] As shown in the plan view of FIG. 1 , the negative electrode side current collector layer 4 has a shape that is line-symmetrical to the positive electrode side current collector layer 3 shown in FIG. 3 . The negative electrode side current collector layer 4 has a negative electrode side current collector body portion 10 and a negative electrode side current collector protrusion portion 11. The outer peripheral edge 10 a of the negative electrode side current collector body portion 10 is located inside the outer peripheral edge 5 a of the solid electrolyte layer 5. The outer peripheral edge 10 a of the negative electrode side current collector body portion 10 is located outside the outer peripheral edge 6 a of the positive electrode layer 6. The outer peripheral edge 10 a of the negative electrode side current collector body portion 10 is located at the same position as the outer peripheral edge 7 a of the negative electrode layer 7. In this way, it is desirable that the outer peripheral edge 10 a of the negative electrode side current collector body portion 10 is located inside the outer peripheral edge 5 a of the solid electrolyte layer 5, but not inside the outer peripheral edge 6 a of the positive electrode layer 6 or the outer peripheral edge 7 a of the negative electrode layer 7. In addition, it is preferable that the negative electrode current collector main body 10 and the negative electrode layer 7 have similar shapes in plan view.

[0032] The negative electrode current collector protrusions 11 are protrusions that protrude from the end surface 10b of the negative electrode current collector main body 10. In this embodiment, the planar shape of the negative electrode current collector main body 10 is approximately rectangular, and a pair of negative electrode current collector protrusions 11 are provided at opposing corners 10c of the negative electrode current collector main body 10. Similarly to the positive electrode current collector protrusions 9, the negative electrode current collector protrusions 11 are connected to two sides of the outer circumferential edge 10a of the negative electrode current collector main body 10 at the corners 10c of the negative electrode current collector main body 10. In the present invention, it is sufficient that the negative electrode current collector layer 4 has at least one negative electrode current collector protrusion 11.

[0033] The negative electrode current collector protruding portion 11 has a negative electrode current collector protruding end surface 11a that is aligned with the end surface 5b of the solid electrolyte layer 5. In this embodiment, a connecting end surface 11b is provided that connects the end surface 10b of the negative electrode current collector main body portion 10 and the negative electrode current collector protruding end surface 11a. The angle between the extension direction of the end surface 10b of the negative electrode current collector main body portion 10 and the extension direction of the connecting end surface 11b (e.g., the angle corresponding to θ in FIG. 3 ) is preferably not a right angle but an acute angle. In this case, the connecting end surface 11b extends obliquely with respect to the extension direction of the end surface 10b of the negative electrode current collector main body portion 10, making it less likely for the negative electrode current collector protruding portion 11 to get caught or bend during stacking, and allowing for faster and easier stacking operations. Furthermore, since the connection portion between the negative electrode current collector protrusion 11 and the negative electrode current collector main body 10 can be made wider, bending of the negative electrode current collector protrusion 11 during stacking is less likely to occur. In this embodiment, a tab lead 14 is connected to the negative electrode current collector protrusion 11. The tab lead 14 is disposed in a position that is line-symmetrical to the tab lead 13.

[0034] The secondary battery 1 of this embodiment has the above-described configuration, and therefore is highly manufacturable and is less likely to cause a short circuit between the positive electrode current collector and the negative electrode current collector.

[0035] In the past, when stacking units of energy storage elements each having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer in the manufacture of secondary batteries, a short circuit could occur due to contact between a positive electrode current collector layer, a positive electrode tab lead, or another positive electrode current collector layer and a negative electrode current collector layer, a negative electrode tab lead, or another negative electrode current collector layer. Therefore, when stacking units of energy storage elements, a device such as an alignment camera could be used to position the energy storage elements and the current collectors to prevent short circuits due to misalignment of the current collectors. However, such devices are expensive, and stacking the energy storage elements and current collectors after positioning them requires time, resulting in problems such as reduced productivity of the resulting secondary batteries. Furthermore, after stacking the energy storage elements and current collectors, internal short circuits could occur due to misalignment of the current collectors.

[0036] 16 and 17 , in the secondary battery 101 of Comparative Example 1, the outer peripheral edge 103a of the positive electrode-side current collector layer 103 is located at the same position as the outer peripheral edge of the energy storage element 102 (the outer peripheral edge 105a of the solid electrolyte layer 105 in Comparative Example 1). Also, the outer peripheral edge 104a of the negative electrode-side current collector layer 104 is located at the same position as the outer peripheral edge of the energy storage element 102 (the outer peripheral edge 105a of the solid electrolyte layer 105 in Comparative Example 1). In the case of the secondary battery 101 of Comparative Example 1, in which the outer peripheral edges of the positive electrode side current collector layer 103 and the negative electrode side current collector layer 104 are positioned at the same position as the outer peripheral edge of the energy storage element 102, when stacking units of the energy storage element 102, there are cases in which a short circuit occurs due to contact between a positive electrode side current collector member such as the positive electrode side current collector layer 103 or the positive electrode side tab lead 106 and a negative electrode side current collector member such as the negative electrode side current collector layer 104 or the negative electrode side tab lead 107. Furthermore, after stacking the energy storage element 102, the positive electrode side current collector layer 103, and the negative electrode side current collector layer 104, there are also cases in which a short circuit occurs due to misalignment of the positive electrode side current collector member and the negative electrode side current collector member.

[0037] In addition, in the secondary battery 111 of Comparative Example 2 shown in FIG. 18 , the outer peripheral edge 113a of the positive electrode-side current collector layer 113 is disposed inside the outer peripheral edge of the energy storage element 112 (in Comparative Example 2, the outer peripheral edge 115a of the solid electrolyte layer 115). In addition, the outer peripheral edge 114a of the negative electrode-side current collector layer 114 is disposed inside the outer peripheral edge of the energy storage element 112 (in Comparative Example 2, the outer peripheral edge 115a of the solid electrolyte layer 115). Therefore, in the secondary battery 111 of Comparative Example 2, when stacking the positive electrode-side current collector layer 113 and the negative electrode-side current collector layer 114, which are slightly smaller than the energy storage element 112, it was necessary to position them using a device such as an alignment camera. However, devices such as alignment cameras are expensive, and it takes time to stack the positive electrode-side current collector layer 113 and the negative electrode-side current collector layer 114 after positioning them, which poses a problem of reduced productivity of the resulting secondary battery 111.

[0038] In contrast, in the secondary battery 1 of this embodiment, the positive electrode side current collector body 8 constituting the positive electrode side current collector layer 3 is disposed inside the outer periphery of the energy storage element 2 (in this embodiment, the outer periphery 5 a of the solid electrolyte layer 5), and the negative electrode side current collector body 10 constituting the negative electrode side current collector layer 4 is disposed inside the outer periphery of the energy storage element 2 (in this embodiment, the outer periphery 5 a of the solid electrolyte layer 5). As such, in the secondary battery 1 of this embodiment, the positive electrode side current collector body 8 and the negative electrode side current collector body 10 are slightly smaller in size than the energy storage element 2, so that a short circuit is less likely to occur between a positive electrode side current collecting member such as the positive electrode side current collector layer 3 or tab lead 13 and a negative electrode side current collecting member such as the negative electrode side current collector layer 4 or tab lead 14. Furthermore, in the secondary battery 1 of this embodiment, the positive electrode side current collector protruding portion 9 constituting the positive electrode side current collector layer 3 has a positive electrode side current collector protruding end surface 9a that is aligned with the end surface 5b of the solid electrolyte layer 5, and the negative electrode side current collector protruding portion 11 constituting the negative electrode side current collector layer 4 has a negative electrode side current collector protruding end surface 11a that is aligned with the end surface 5b of the solid electrolyte layer 5. Therefore, for example, positioning members 12A, 12B can be placed in advance at the positions where the positive electrode side current collector protruding end surface 9a and the negative electrode side current collector protruding end surface 11a are to be positioned, and the positive electrode side current collector layer 3, the energy storage element 2, and the negative electrode side current collector layer 4 can be positioned such that the positive electrode side current collector protruding end surface 9a, the end surface 5b of the solid electrolyte layer 5, and the negative electrode side current collector protruding end surface 11a are aligned with the positions of the positioning members 12A, 12B. Therefore, in the secondary battery 1 of this embodiment, the positive electrode current collector layer 3, the energy storage element 2, and the negative electrode current collector layer 4 can be easily positioned without using an expensive device such as an alignment camera. Therefore, the secondary battery 1 of this embodiment has excellent productivity. This point will be described in detail in the section on the manufacturing method of a secondary battery below.

[0039] In the secondary battery 1 of this embodiment, in plan view, there is no overlap between the positive electrode-side current collector protruding end surface 9a of the positive electrode-side current collector layer 3 and the negative electrode-side current collector protruding end surface 11a of the negative electrode-side current collector layer 4. Therefore, also from this point of view, short circuits are unlikely to occur between positive electrode-side current collector members such as the positive electrode-side current collector layer 3 and tab lead 13 and negative electrode-side current collector members such as the negative electrode-side current collector layer 4 and tab lead 14. Therefore, the secondary battery 1 of this embodiment is excellent in productivity and is unlikely to short between the positive electrode-side current collector member and the negative electrode-side current collector member.

[0040] Each layer constituting the secondary battery 1 will be described in detail below.

[0041] (Solid Electrolyte Layer) The solid electrolyte layer 5 is composed of an ion-conductive material such as a sodium ion-conductive oxide. Examples of sodium ion-conductive oxides include compounds containing at least one element selected from Al, Y, Zr, Si, and P, Na, and O. Specific examples of sodium ion-conductive oxides include beta-alumina and NASICON crystal, which have excellent sodium ion conductivity. Of these, beta-alumina is preferred as the sodium ion-conductive oxide from the viewpoint of achieving even better sodium ion conductivity.

[0042] Beta alumina includes β-alumina (theoretical composition formula: Na ２ O.11Al ２ O ３ ) and β″-alumina (theoretical composition formula: Na ２ O 5.3 Al ２ O ３ β"-alumina is a metastable material, so it is usually ２ The beta-alumina to which O or MgO is added as a stabilizer is used. Since β"-alumina has a higher sodium ion conductivity than β-alumina, it is preferable to use β"-alumina alone or a mixture of β"-alumina and β-alumina as the beta-alumina. ２ It is more preferable to use O-stabilized β"-alumina or MgO-stabilized β"-alumina.

[0043] Specific examples of β″-alumina include (Al１０．３５ Mg ０．６５ O １６ ) (Na １．６５ O), (Al ８．８７ Mg ２．１３ O １６ ) (Na ３．１３ O), Na １．６７ Mg ０．６７ Al １０．３３ O １７ Trigonal MgO-stabilized β″-alumina such as Na １．４９ Li ０．２５ Al １０．７５ O １７ , Na １．７２ Li ０．３ Al １０．６６ O １７ , Na １．６ Li ０．３４ Al １０．６６ O １７ Trigonal Li such as ２ O-stabilized β″-alumina.

[0044] Specific examples of β-alumina include hexagonal (Al １０．３５ Mg ０．６５ O １６ ) (Na １．６５ O), (Al １０．３７ Mg ０．６３ O １６ ) (Na １．６３ O), NaAl １１ O １７ , (Al １０．３２ Mg ０．６８ O １６ ) (Na １．６８ O) and the like.

[0045] NASICON crystals include Na ３ Zr ２ Si ２ P.O. １２ , Na ３．２ Zr １．３ Si ２．２ P ０．７ O １０．５ , Na ３ Zr １．６ Ti ０．４ Si ２ P.O. １２ , Na ３ Hf ２ Si ２PO １２ 、No ３．４ Zr ０．９ Hf １．４ Al ０．６ Yes １．２ P １．８ O １２ 、No ３ Zr １．７ N﹂ ０．２４ Yes ２ PO １２ 、No ３．６ Today ０．２ Y ０．８ Yes ２．８ O ９ 、No ３ Zr １．８８ Y ０．１２ Yes ２ PO １２ 、No ３．１２ Zr １．８８ Y ０．１２ Yes ２ PO １２ 、No ３．０５ Zr ２ Yes ２．０６ P ０．９５ O １２ 、No ３．４ Zr ２ Yes ２．４ P ０．６ O １２ 、No ３．４ Zr １．９ Zn ０．１ Yes ２．４ P ０．６ O １２ 、No ３．４ Zr １．９ Mg ０．１ Yes ２．４ P ０．６ O １２ 、No ３．４ Zr １．９ Zn ０．１ Yes ２．２ P ０．８ O １２ 、No ３．４ Zr １．９ Mg ０．１ Yes ２．２ P ０．８ O １２ 、No ２．８ Zr ２ Yes ２．４ P ０．６ O １２ 、No５ YSi ４ O １２ 、No ３．１ Zr １．９５ Mg ０．０５ Yes ２ PO １２ 、No ３．１ Zr １．９ Yes ０．１ Yes ２ PO １２ 、No ３．１ Zr １．９ N$ ０．１ Yes ２ PO １２ 、No ３．１ Zr １．９ Y ０．１ Yes ２ PO １２ 、No ３．２５６ Zr １．８７２ Mg ０．１２８ Yes ２ PO １２ 、No ３．２ Zr １．９ Ca ０．１ Yes ２ PO １２ 、No ３．２ Zr １．９ Mg ０．１ Yes ２ PO １２ 、No ３．２ Zr ２ Yes ２．２ P ０．８ O １２ 、No ３．３８ Zr １．８０ Al ０．２６ Yes ２．０６ P ０．８８ O １２ 、No ３．４３ Zr １．８３ Zn ０．２２ Yes １．９３ P １．０２ O １２ 、No ３．４ Sc ０．４ Zr １．６ Yes ２ PO １２ 、No ３．４ Zr １．８ Mg ０．２ Yes ２ PO １２ 、No ３．４ Zr１．９ Zn ０．１ Si ２．２ P ０．８ O １２ , Na ３．５７ Zr １．７２ La ０．２１ Si ２．０８ P ０．９２ O １２ , Na ３ Zr １．９８ Nb ０．０８ Si ２ P.O. １２ , Na ３ Zr １．９ Ce ０．１ Si ２ P.O. １２ , Na ３ Zr １．９ Ce ０．１ Si ２ P.O. １２ , Na ３ Zr １．９ Gd ０．１ Si ２ P.O. １２ , Na ３ Zr １．９ Ti ０．１ Si ２ P.O. １２ , Na ３ Zr １．９ Yb ０．１ Si ２ P.O. １２ , or Na ３．６ Zr ０．１３ Yb １．６７ Si ０．１１ P ２．９ O １２ These may be used alone or in combination. From the viewpoint of superior sodium ion conductivity, Na ３ Zr ２ Si ２ P.O. １２ , Na ３．４ Zr ２ Si ２．４ P ０．６ O １２、 or Na ３．０５ Zr ２ Si ２．０６ P ０．９５ O １２It is preferable to use

[0046] The solid electrolyte layer 5 can be produced by mixing raw material powders, molding the mixed raw material powders, and then firing the molded product. For example, the solid electrolyte layer 5 can be produced by forming a green sheet from the raw material powders into a slurry, and then firing the green sheet. The solid electrolyte layer 5 may also be produced by a sol-gel method.

[0047] The thickness of the solid electrolyte layer 5 is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 15 μm or more, and preferably 1000 μm or less, more preferably 200 μm or less, and even more preferably 100 μm or less. When the thickness of the solid electrolyte layer 5 is equal to or greater than the above-mentioned lower limit, the mechanical strength of the secondary battery 1 can be further increased, making it less susceptible to breakage and internal short circuits. When the thickness of the solid electrolyte layer 5 is equal to or less than the above-mentioned upper limit, the internal resistance can be further reduced, making it possible to further improve the capacity and operating voltage of the secondary battery 1. Furthermore, the energy density per unit volume of the secondary battery 1 can be further improved.

[0048] (Positive Electrode Layer) The positive electrode layer 6 contains a positive electrode active material capable of absorbing and releasing sodium. The positive electrode active material contained in the positive electrode layer 6 is not particularly limited, but for example, a positive electrode active material represented by the general formula Na ｘ M ｙ P ２ O ｚ (1≦x≦2.8, 0.95≦y≦1.6, 6.5≦z≦8, M is at least one element selected from the group consisting of Fe, Ni, Co, Mn, and Cr) can be used as a positive electrode active material. ｘ MP ２ O ７ (1≦x≦2, M is at least one selected from the group consisting of Fe, Ni, Co, Mn, and Cr). ２ FeP ２ O ７ , Na ２ CoP ２O ７ , or Na ２ NiP ２ O ７ etc. can be used.

[0049] In this specification, crystallized glass refers to the precursor glass containing amorphous phase that is heated (fired) to precipitate crystals (crystallization).In crystallized glass, all of the amorphous phase may be transformed into crystalline phase, or amorphous phase may remain.In addition, in crystallized glass, one type of crystal may be precipitated, or two or more types of crystal may be precipitated.For example, it is possible to determine whether crystallized glass is crystallized glass by the peak angle shown by powder X-ray diffraction (XRD).

[0050] The positive electrode layer 6 may contain a sodium ion conductive solid electrolyte and a conductive additive in addition to the positive electrode active material. The positive electrode layer 6 may contain, for example, 60% to 99.9% by mass of the positive electrode active material, 0% to 30% by mass of the sodium ion conductive solid electrolyte, and 0.1% to 10% by mass of the conductive additive.

[0051] The sodium ion conductive solid electrolyte may be, for example, one of those described in the section on the solid electrolyte layer 5. The conductive additive may be, for example, conductive carbon. Examples of conductive carbon include acetylene black, carbon black, ketjen black, vapor grown carbon fiber (VGCF), and carbon nanotubes.

[0052] The positive electrode layer 6 can be formed, for example, by forming an electrode material layer on a main surface of the solid electrolyte layer 5 and firing the electrode material layer. The electrode material layer can be obtained, for example, by applying a paste containing a positive electrode active material precursor and, if necessary, a solid electrolyte powder and a conductive additive, followed by drying. The paste may contain, if necessary, a binder, a plasticizer, a solvent, or the like. The electrode material layer may be a powder compact.

[0053] The thickness of the positive electrode layer 6 is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 20 μm or more, and is preferably 200 μm or less, more preferably 100 μm or less, and even more preferably 50 μm or less. When the thickness of the positive electrode layer 6 is equal to or greater than the above-mentioned lower limit, the capacity of the secondary battery 1 can be further improved. When the thickness of the positive electrode layer 6 is equal to or less than the above-mentioned upper limit, the capacity and operating voltage of the secondary battery 1 can be further improved, and the positive electrode layer 6 is less likely to shrink due to firing when formed, and the positive electrode layer 6 can be less likely to peel off.

[0054] A metal thin film may be provided on the main surface of the positive electrode layer 6 facing the positive electrode-side current collector layer 3. In this case, the electronic conductivity at the interface between the positive electrode layer 6 and the positive electrode-side current collector layer 3 can be further increased. The metal thin film may be, for example, an aluminum film. The metal thin film may be formed by, for example, a sputtering method or a vacuum deposition method. In particular, from the viewpoint of improving adhesion to the positive electrode layer 6, the metal thin film is preferably a sputtered film formed by a sputtering method.

[0055] (Negative Electrode Layer) The negative electrode layer 7 contains a negative electrode active material capable of absorbing and releasing sodium. The negative electrode active material contained in the negative electrode layer 7 is not particularly limited, but for example, a carbon electrode material such as hard carbon or soft carbon can be used. The carbon electrode material is preferably hard carbon. However, the negative electrode active material may be an alloy-based negative electrode active material capable of absorbing sodium, such as tin, bismuth, lead, or phosphorus, or may contain metallic sodium. Note that the negative electrode layer 7 is preferably not a negative electrode layer consisting of a single phase of metallic sodium.

[0056] The negative electrode layer 7 may contain, in addition to the negative electrode active material, a sodium ion conductive solid electrolyte and a conductive additive. The negative electrode layer 7 may contain, for example, by mass %, 60% to 95% of the negative electrode active material, 5% to 35% of the sodium ion conductive solid electrolyte, and 0% to 5% of the conductive additive.

[0057] The sodium ion conductive solid electrolyte may be, for example, one described in the section on the solid electrolyte layer 5. The conductive additive may be, for example, one described in the section on the positive electrode layer 6.

[0058] The anode layer 7 can be formed, for example, by forming an electrode material layer on a main surface of the solid electrolyte layer 5 and firing the electrode material layer. The electrode material layer can be obtained, for example, by applying and drying a paste containing a carbon electrode material precursor (a precursor of a carbon electrode material made of hard carbon) and, as needed, a sodium ion conductive solid electrolyte and a conductive additive. The paste may contain, as needed, a binder, a plasticizer, a solvent, or the like. The electrode material layer may be a compact.

[0059] The thickness of the anode layer 7 is preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more, and is preferably 200 μm or less, more preferably 100 μm or less, and even more preferably 50 μm or less. When the thickness of the anode layer 7 is equal to or greater than the above lower limit, the capacity of the secondary battery 1 can be further improved. When the thickness of the anode layer 7 is equal to or less than the above upper limit, the capacity and operating voltage of the secondary battery 1 can be further improved.

[0060] A metal thin film may be provided on the main surface of the negative electrode layer 7 facing the negative electrode-side current collector layer 4. In this case, the electronic conductivity at the interface between the negative electrode layer 7 and the negative electrode-side current collector layer 4 can be further increased. The metal thin film may be, for example, an aluminum film. The metal thin film may be formed by, for example, a sputtering method or a vacuum deposition method. In particular, from the viewpoint of improving adhesion to the negative electrode layer 7, the metal thin film is preferably a sputtered film formed by a sputtering method.

[0061] (Positive Electrode-Side Current Collector Layer and Negative Electrode-Side Current Collector Layer) The materials for the positive electrode-side current collector layer 3 and the negative electrode-side current collector layer 4 are not particularly limited, and metal materials such as aluminum, titanium, silver, copper, stainless steel (SUS), or alloys thereof can be used, respectively. These metal materials may be used alone or in combination. The alloy is an alloy containing at least one of the above metals. In this embodiment, the positive electrode-side current collector layer 3 is made of aluminum, and the negative electrode-side current collector layer 4 is made of aluminum, but is not limited thereto.

[0062] The thickness of each of the positive electrode-side current collector layer 3 and the negative electrode-side current collector layer 4 is preferably 5 μm or more, more preferably 8 μm or more, and even more preferably 10 μm or more, and is preferably 50 μm or less, more preferably 20 μm or less, and even more preferably 15 μm or less. When the thicknesses of the positive electrode-side current collector layer 3 and the negative electrode-side current collector layer 4 are within the above ranges, the current collecting function as a current collector can be further improved.

[0063] The material of the positive electrode tab lead 13 may be, for example, the same as that of the positive electrode current collector layer 3. The material of the negative electrode tab lead 14 may be, for example, the same as that of the negative electrode current collector layer 4.

[0064] A method for manufacturing the secondary battery 1 will now be described.

[0065] (Secondary Battery Manufacturing Method) In the method for manufacturing the secondary battery 1 of this embodiment, first, the energy storage element 2, the positive electrode current collector layer 3, and the negative electrode current collector layer 4 are prepared. Next, the positive electrode current collector positioning member 12A is placed at the intended position for the positive electrode current collector protruding end face 9a. Furthermore, the negative electrode current collector positioning member 12B is placed at the intended position for the negative electrode current collector protruding end face 11a.

[0066] Next, the positive electrode current collector layer 3 is placed so that the positive electrode current collector protruding end surface 9a is aligned with the position of the positive electrode current collector positioning member 12A. The energy storage element 2 is placed so that the end surface 5b of the solid electrolyte layer 5 is aligned with the positions of the positive electrode current collector positioning member 12A and the negative electrode current collector positioning member 12B. The negative electrode current collector layer 4 is placed so that the negative electrode current collector protruding end surface 11a is aligned with the position of the negative electrode current collector positioning member 12B. The positive electrode current collector layer 3, the energy storage element 2, and the negative electrode current collector layer 4 are stacked in the appropriate order in this manner, aligned with the positions of the positive electrode current collector positioning member 12A and the negative electrode current collector positioning member 12B, to obtain the secondary battery 1.

[0067] As described above, in the method for manufacturing the secondary battery 1 of this embodiment, the positioning of the positive electrode side current collector layer 3, the energy storage element 2, and the negative electrode side current collector layer 4 can be easily performed using the positive electrode side current collector positioning member 12A and the negative electrode side current collector positioning member 12B without using expensive equipment such as an alignment camera, thereby improving the productivity of the secondary battery 1.

[0068] Although positioning pins, for example, can be used as the positive electrode current collector positioning members 12A and the negative electrode current collector positioning members 12B, the method for manufacturing the secondary battery 1 of this embodiment may also use case members as positioning members. In this case, the secondary battery 1 can be manufactured as follows.

[0069] First, the energy storage element 2, the positive electrode-side current collector layer 3, and the negative electrode-side current collector layer 4 are prepared. Next, a case member is prepared to house the energy storage element 2, the positive electrode-side current collector layer 3, and the negative electrode-side current collector layer 4. As the case member, for example, a case member having a bottom surface corresponding to the planar shape of the solid electrolyte layer 5 can be used.

[0070] Next, the positive electrode side current collector layer 3 is placed on the inner wall surface of the case member so that the protruding end surface 9a of the positive electrode side current collector is aligned. The energy storage element 2 is placed on the inner wall surface of the case member so that the end surface 5b of the solid electrolyte layer 5 is aligned. The negative electrode side current collector layer 4 is placed on the inner wall surface of the case member so that the protruding end surface 11a of the negative electrode side current collector is aligned. In this way, the positive electrode side current collector layer 3, the energy storage element 2, and the negative electrode side current collector layer 4 are housed in the case member in the appropriate order, aligned with the positions of the inner wall surface of the case member, to obtain the secondary battery 1.

[0071] In this manufacturing method, too, the positive electrode-side current collector layer 3, the energy storage element 2, and the negative electrode-side current collector layer 4 can be easily positioned using the inner wall surface of the case member without using expensive equipment such as an alignment camera, thereby improving the productivity of the secondary battery 1.

[0072] [Second to Sixth Embodiments] Fig. 4 is a schematic plan view showing a secondary battery according to a second embodiment of the present invention, and Fig. 5 is a schematic plan view showing a positive electrode-side current collector layer constituting the secondary battery according to the second embodiment of the present invention.

[0073] 4, in a secondary battery 21 of the second embodiment, in a plan view, tab leads 13 and 14 are provided inside corners of a solid electrolyte layer 5. Other points are the same as those of the first embodiment.

[0074] As in the second embodiment, the positions at which the tab leads 13 and 14 are provided are not particularly limited as long as the tab leads 13 and 14 do not have an overlapping portion in plan view. When the tab leads 13 and 14 are positioned inside the corners of the solid electrolyte layer 5 as in the second embodiment, for example, a positive electrode-side current collector positioning member 12A can be disposed between the corners of the solid electrolyte layer 5 and the tab leads 13, and a negative electrode-side current collector positioning member 12B can be disposed between the corners of the solid electrolyte layer 5 and the tab leads 14, making it even easier to position the positive electrode-side current collector layer 3 and the negative electrode-side current collector layer 4.

[0075] Fig. 6 is a schematic plan view showing a secondary battery according to a third embodiment of the present invention. Fig. 7 is a schematic plan view showing a positive electrode side current collector layer constituting the secondary battery according to the third embodiment of the present invention.

[0076] As shown in Fig. 6 , in a secondary battery 31 of the third embodiment, the planar shapes of the positive electrode layer 6, the negative electrode layer 7, and the solid electrolyte layer 5 are substantially hexagonal. The planar shape of the positive electrode side current collector body 8 is also substantially hexagonal, and a positive electrode side current collector protrusion 9 is provided so as to protrude from an end face 8b of the positive electrode side current collector body 8. The planar shape of the negative electrode side current collector body 10 is also substantially hexagonal, and a negative electrode side current collector protrusion 11 is provided so as to protrude from an end face 10b of the negative electrode side current collector body 10. Other points are the same as those of the first embodiment.

[0077] Fig. 8 is a schematic plan view showing a secondary battery according to a fourth embodiment of the present invention, and Fig. 9 is a schematic plan view showing a positive electrode-side current collector layer constituting the secondary battery according to the fourth embodiment of the present invention.

[0078] As shown in FIG. 8 , in a secondary battery 41 of the fourth embodiment, the positive electrode layer 6, the negative electrode layer 7, and the solid electrolyte layer 5 have a substantially circular planar shape. The positive electrode collector body 8 has a substantially circular planar shape, and a positive electrode collector projection 9 is provided so as to project from an end face 8 b of the positive electrode collector body 8. The negative electrode collector body 10 has a substantially circular planar shape, and a negative electrode collector projection 11 is provided so as to project from an end face 10 b of the negative electrode collector body 10. The positive electrode collector layer 3 has two opposing positive electrode collector projections 9. The negative electrode collector layer 4 has two opposing negative electrode collector projections 11 in a direction perpendicular to the direction in which the two positive electrode collector projections 9 face each other. Other features are similar to those of the first embodiment.

[0079] As in the third and fourth embodiments, the planar shapes of the positive electrode layer 6, the negative electrode layer 7, the solid electrolyte layer 5, the positive electrode-side current collector body 8, and the negative electrode-side current collector body 10 do not have to be substantially rectangular, but may be substantially polygonal or circular. Furthermore, as in the fourth embodiment, the positive electrode-side current collector layer 3 and the negative electrode-side current collector layer 4 do not have to be arranged so as to be line-symmetrical in plan view. In the present invention, it is sufficient that the positive electrode-side current collector protrusion 9 of the positive electrode-side current collector layer 3 and the negative electrode-side current collector protrusion 11 of the negative electrode-side current collector layer 4 do not overlap. Furthermore, it is sufficient that the positive electrode-side tab lead 13 and the negative electrode-side tab lead 14 do not overlap in plan view.

[0080] Fig. 10 is a schematic plan view showing a secondary battery according to a fifth embodiment of the present invention. Fig. 11 is a schematic cross-sectional view showing a portion along line BB in Fig. 10. Fig. 12 is a schematic plan view showing a positive electrode-side current collector layer constituting the secondary battery according to the fifth embodiment of the present invention.

[0081] As shown in Fig. 10, a secondary battery 51 of the fifth embodiment is a coin cell, and is not provided with tab leads 13 and 14. Also, as shown in Fig. 11, the secondary battery 51 is provided with only one energy storage element 2, and has a negative electrode current collector layer 4, the energy storage element 2, and a positive electrode current collector layer 3 stacked in this order. Other points are the same as those of the fourth embodiment.

[0082] As in the fifth embodiment, the secondary battery 51 may be a coin cell.

[0083] FIG. 13 is a schematic cross-sectional view showing a secondary battery according to a sixth embodiment of the present invention.

[0084] 13 , a secondary battery 61 of the sixth embodiment has four energy storage elements 2. Each energy storage element 2 is arranged so as to be sandwiched between a positive electrode-side current collector layer 3 and a negative electrode-side current collector layer 4. In each energy storage element 2, a positive electrode layer 6 is arranged on the positive electrode-side current collector layer 3 side, and a negative electrode layer 7 is arranged on the negative electrode-side current collector layer 4 side. A solid electrolyte layer 5 is arranged so as to be sandwiched between the positive electrode layer 6 and the negative electrode layer 7. In the secondary battery 61, energy storage elements 2 adjacent to each other in the stacking direction share the positive electrode-side current collector layer 3 or the negative electrode-side current collector layer 4.

[0085] The secondary battery 61 of the sixth embodiment is an all-solid-state lithium ion secondary battery. Therefore, the positive electrode layer 6, the negative electrode layer 7, and the solid electrolyte layer 5 are made of materials used in conventionally known all-solid-state lithium ion secondary batteries. The other points are the same as those of the first embodiment.

[0086] As in the sixth embodiment, the number of energy storage elements 2 included in the secondary battery of the present invention may be four, and there is no particular limitation on the number of energy storage elements 2. Furthermore, the secondary battery of the present invention may be an all-solid-state lithium ion secondary battery, and is applicable to any appropriate all-solid-state secondary battery.

[0087] In the secondary batteries of the second to sixth embodiments, the positive electrode side current collector body 8 and the negative electrode side current collector body 10 are also slightly smaller in size than the energy storage element 2, and therefore short circuits are less likely to occur between positive electrode side current collector members such as the positive electrode side current collector layer 3 and the tab lead 13 and negative electrode side current collector members such as the negative electrode side current collector layer 4 and the tab lead 14. Furthermore, in the secondary batteries of the second to sixth embodiments, the positive electrode side current collector protruding portion 9 constituting the positive electrode side current collector layer 3 has a positive electrode side current collector protruding end surface 9a that is aligned with the end surface 5b of the solid electrolyte layer 5, and the negative electrode side current collector protruding portion 11 constituting the negative electrode side current collector layer 4 has a negative electrode side current collector protruding end surface 11a that is aligned with the end surface 5b of the solid electrolyte layer 5. Therefore, for example, positioning members 12A, 12B can be placed in advance at the positions where the positive electrode-side current collector protruding end face 9 a and the negative electrode-side current collector protruding end face 11 a are to be placed, and the positive electrode-side current collector layer 3, the energy storage element 2, and the negative electrode-side current collector layer 4 can be placed by aligning the positive electrode-side current collector protruding end face 9 a, the end face 5 b of the solid electrolyte layer 5, and the negative electrode-side current collector protruding end face 11 a with the positions of positioning members 12A, 12B. Therefore, the secondary batteries of the second to sixth embodiments are excellent in productivity because the positive electrode-side current collector layer 3, the energy storage element 2, and the negative electrode-side current collector layer 4 can be easily positioned without using an expensive device such as an alignment camera.

[0088] In the secondary batteries of the second to sixth embodiments, too, there is no overlap between the positive electrode-side current collector protruding end surface 9a of the positive electrode-side current collector layer 3 and the negative electrode-side current collector protruding end surface 11a of the negative electrode-side current collector layer 4 in plan view. Therefore, also from this point of view, a short circuit is unlikely to occur between a positive electrode-side current collector member such as the positive electrode-side current collector layer 3 or tab lead 13 and a negative electrode-side current collector member such as the negative electrode-side current collector layer 4 or tab lead 14. Therefore, the secondary batteries of the second to sixth embodiments are excellent in productivity and are unlikely to cause a short circuit between the positive electrode-side current collector member and the negative electrode-side current collector member.

[0089] Seventh Embodiment Fig. 14 is a schematic plan view showing a secondary battery according to a seventh embodiment of the present invention, and Fig. 15 is a schematic cross-sectional view showing a portion along line CC in Fig. 14.

[0090] 14 and 15, the secondary battery 71 is a liquid electrolyte lithium ion secondary battery, and has a separator 75 instead of the solid electrolyte layer 5.

[0091] The separator 75 is provided between the positive electrode layer 6 and the negative electrode layer 7 and is a layer with high ionic conductivity but low electronic conductivity. The separator 75 can be made of, for example, an insulating material. Specifically, the separator 75 can be made of, for example, a porous film or nonwoven fabric obtained from a polymer such as polyolefin, cellulose, polyethylene terephthalate, or vinylon; a glass nonwoven fabric containing fibrous glass; a glass cloth woven from fibrous glass; or a glass film.

[0092] As the electrolyte, for example, an organic solvent-based electrolyte, an ionic liquid, etc. can be used. As the organic solvent-based electrolyte, for example, 1M LiPF ６ EC: DEC or 1M LiPF ６ PC or the like can be used. As the ionic liquid, for example, a solution of LiFSI or LiTFSI in Pyr13FSI, EMIMFSI, MPPyFSI or the like can be used.

[0093] Other points are the same as those in the sixth embodiment.

[0094] As in the seventh embodiment, the secondary battery of the present invention may be a liquid electrolyte lithium ion secondary battery. The liquid electrolyte secondary battery may also be a sodium ion secondary battery, and the secondary battery of the present invention is generally applicable to other liquid electrolyte secondary batteries.

[0095] In the secondary battery 71 of the seventh embodiment, the positive electrode side current collector body 8 and the negative electrode side current collector body 10 are slightly smaller in size than the energy storage element 72, and therefore a short circuit is less likely to occur between positive electrode side current collecting members such as the positive electrode side current collector layer 3 and the tab lead 13 and negative electrode side current collecting members such as the negative electrode side current collector layer 4 and the tab lead 14. Furthermore, in the secondary battery 71 of the seventh embodiment, the positive electrode side current collector protrusion 9 constituting the positive electrode side current collector layer 3 has a positive electrode side current collector protruding end face 9a arranged so as to align with the end face 75b of the separator 75, and the negative electrode side current collector protrusion 11 constituting the negative electrode side current collector layer 4 has a negative electrode side current collector protruding end face 11a arranged so as to align with the end face 75b of the separator 75. Therefore, for example, positioning members 12A, 12B can be placed in advance at the positions where the positive electrode side current collector protruding end surface 9 a and the negative electrode side current collector protruding end surface 11 a are to be placed, and the positive electrode side current collector layer 3, the energy storage element 72, and the negative electrode side current collector layer 4 can be placed by aligning the positive electrode side current collector protruding end surface 9 a, the end surface 75 b of the separator 75, and the negative electrode side current collector protruding end surface 11 a with the positions of the positioning members 12A, 12B. Therefore, the secondary battery 71 of the seventh embodiment has excellent productivity because the positive electrode side current collector layer 3, the energy storage element 72, and the negative electrode side current collector layer 4 can be easily positioned without using an expensive device such as an alignment camera.

[0096] In the secondary battery 71 of the seventh embodiment, in plan view, there is no overlap between the positive electrode-side current collector protruding end surface 9 a of the positive electrode-side current collector layer 3 and the negative electrode-side current collector protruding end surface 11 a of the negative electrode-side current collector layer 4. Therefore, also from this point of view, short circuits are unlikely to occur between positive electrode-side current collector members such as the positive electrode-side current collector layer 3 and tab lead 13 and negative electrode-side current collector members such as the negative electrode-side current collector layer 4 and tab lead 14. Therefore, the secondary battery 71 of the seventh embodiment is excellent in productivity and is unlikely to short between the positive electrode-side current collector member and the negative electrode-side current collector member.

[0097] DESCRIPTION OF SYMBOLS 1, 21, 31, 41, 51, 61, 71... Secondary battery 2, 72... Energy storage element 3... Positive electrode side collector layer 4... Negative electrode side collector layer 5... Solid electrolyte layer 5a, 6a, 7a, 8a... Outer periphery 8a1, 8a2... Side 5b, 8b, 75b... End face 6... Positive electrode layer 7... Negative electrode layer 8... Positive electrode side collector main body 8c, 10c... Corner 9... Positive electrode side collector protruding portion 9a... Positive electrode side collector protruding end face 9b, 11b... Connection end face 10... Negative electrode side collector main body 11... Negative electrode side collector protruding portion 11a... Negative electrode side collector protruding end face 12A... Positive electrode side collector positioning member 12B... Negative electrode side collector positioning member 13, 14... Tab lead 75... Separator

Claims

1. A secondary battery that is an all-solid-state battery comprising an energy storage element having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer, a positive electrode-side current collector layer, and a negative electrode-side current collector layer, wherein, in a plan view, outer peripheral edges of the positive electrode layer and the negative electrode layer are located inside the outer peripheral edge of the solid electrolyte layer, and the positive electrode-side current collector layer comprises the positive electrode-side current collector main body portion that is located inside the outer peripheral edge of the solid electrolyte layer in a plan view, and a positive electrode-side current collector protruding portion that protrudes from an end face of the positive electrode-side current collector main body portion, and the positive electrode-side current collector protruding portion has a positive electrode-side current collector protruding end face that is located so as to be aligned with the end face of the solid electrolyte layer, a negative electrode side current collector layer including, in plan view, the negative electrode side current collector body portion disposed inside an outer peripheral edge of the solid electrolyte layer, and a negative electrode side current collector protruding portion protruding from an end face of the negative electrode side current collector body portion, the negative electrode side current collector protruding portion having a negative electrode side current collector protruding end face disposed so as to be aligned with the end face of the solid electrolyte layer, and the positive electrode side current collector protruding end face and the negative electrode side current collector protruding end face do not have an overlapping portion in plan view.

2. The secondary battery according to claim 1, wherein a plurality of the positive electrode collector protruding portions and a plurality of the negative electrode collector protruding portions are provided.

3. The secondary battery according to claim 1 or 2, wherein tab leads are connected to the positive electrode side current collector protrusion and the negative electrode side current collector protrusion, respectively.

4. A secondary battery as described in claim 1 or 2, wherein the outer peripheral edges of the positive electrode side collector body portion and the negative electrode side collector body portion are not positioned inside the outer peripheral edges of the positive electrode layer and the negative electrode layer.

5. A secondary battery according to claim 1 or 2, wherein, in plan view, the positive electrode side current collector layer has a pair of positive electrode side current collector protrusions arranged in positions facing each other, and the negative electrode side current collector layer has a pair of negative electrode side current collector protrusions arranged in positions facing each other.

6. The secondary battery according to claim 5, wherein, in a plan view, the positive electrode side current collector body portion and the negative electrode side current collector body portion have a substantially rectangular shape, in a plan view, the positive electrode side current collector layer has a pair of positive electrode side current collector protrusions provided at opposing corners of the positive electrode side current collector body portion, and in a plan view, the negative electrode side current collector layer has a pair of negative electrode side current collector protrusions provided at opposing corners of the negative electrode side current collector body portion.

7. The secondary battery according to claim 1 or 2, wherein the positive electrode side current collector body portion and the negative electrode side current collector body portion have a substantially circular shape in a plan view.

8. A secondary battery according to claim 1 or 2, wherein the positive electrode side current collector layer has a connection end face connecting an end face of the positive electrode side current collector main body portion and a protruding end face of the positive electrode side current collector, and the negative electrode side current collector layer has a connection end face connecting an end face of the negative electrode side current collector main body portion and a protruding end face of the negative electrode side current collector.

9. A secondary battery according to claim 1 or 2, which is configured by stacking a plurality of units of the energy storage element, and in the energy storage elements adjacent in the stacking direction, the positive electrode layers or the negative electrode layers are arranged to face each other, the positive electrode side current collector layer is arranged between the positive electrode layers, and the negative electrode side current collector layer is arranged between the negative electrode layers.

10. A method for manufacturing a secondary battery according to claim 1 or 2, comprising the steps of: arranging a positive electrode side current collector positioning member at a position where the positive electrode side current collector protruding end face is to be arranged, and arranging a negative electrode side current collector positioning member at a position where the negative electrode side current collector protruding end face is to be arranged; arranging the positive electrode side current collector layer so that the position of the positive electrode side current collector positioning member aligns with the position of the positive electrode side current collector positioning member; arranging the energy storage element so that the position of the end face of the solid electrolyte layer aligns with the positions of the positive electrode side current collector positioning member and the negative electrode side positioning member; and arranging the negative electrode side current collector layer so that the position of the negative electrode side current collector protruding end face aligns with the position of the negative electrode side current collector positioning member.

11. A method for manufacturing a secondary battery according to claim 1 or 2, comprising the steps of: preparing a case member for housing the energy storage element, the positive electrode side current collector layer, and the negative electrode side current collector layer; arranging the positive electrode side current collector layer so that the protruding end face of the positive electrode side current collector is aligned with the inner wall surface of the case member; arranging the energy storage element so that the end face of the solid electrolyte layer is aligned with the inner wall surface of the case member; and arranging the negative electrode side current collector layer so that the protruding end face of the negative electrode side current collector is aligned with the inner wall surface of the case member.

12. A secondary battery that is an electrolyte battery comprising an energy storage element having a positive electrode layer, a negative electrode layer, and a separator, a positive electrode-side current collector layer, and a negative electrode-side current collector layer, wherein, in a plan view, the outer peripheral edges of the positive electrode layer and the negative electrode layer are located inside the outer peripheral edge of the separator, and the positive electrode-side current collector layer comprises the positive electrode-side current collector body portion that is located inside the outer peripheral edge of the separator in a plan view, and a positive electrode-side current collector protruding portion that protrudes from an end face of the positive electrode-side current collector body portion, and the positive electrode-side current collector protruding portion has a positive electrode-side current collector protruding end face that is located so as to be aligned with the end face of the separator, a negative electrode side current collector layer including, in plan view, the negative electrode side current collector body portion disposed inside an outer peripheral edge of the separator, and a negative electrode side current collector protruding portion protruding from an end face of the negative electrode side current collector body portion, the negative electrode side current collector protruding portion having a negative electrode side current collector protruding end face disposed so as to be aligned with the end face of the separator, and the positive electrode side current collector protruding end face and the negative electrode side current collector protruding end face do not have an overlapping portion in plan view.

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