Secondary battery

Abstract

To provide a secondary battery in which a negative electrode current collecting foil can follow the volume change of a negative electrode active material layer in the secondary battery in which a frame material is provided surrounding the negative electrode active material layer.SOLUTION: A secondary battery 1 includes a solid electrolyte layer 2, a positive electrode active material layer 3, a negative electrode active material layer 4, a negative electrode current collector foil 6, a frame material 7 provided on the solid electrolyte layer 2 to surround the negative electrode active material layer 4. When viewed in the stacking direction, the outer peripheral end of the negative electrode current collector foil 6 is located at the same position as the inner peripheral end of the frame material 7, or, located on the inner side of the inner peripheral end of the frame member 7.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a secondary battery. [Background technology]

[0002] A secondary battery having a solid electrolyte layer, a positive electrode active material layer and a negative electrode active material layer sandwiching the solid electrolyte layer, and a positive electrode current collector foil and a negative electrode current collector foil provided on the positive electrode active material layer and the negative electrode active material layer is known. As such a secondary battery, a battery whose volume can be changed is known. A secondary battery whose volume can be changed needs to be configured so that the volume change is allowed.

[0003] In relation to the above, Patent Document 1 (JP Patent No. 7070052) discloses an all-solid-state battery having an all-solid-state battery laminate with a specific configuration and a resin layer covering a side surface of the all-solid-state battery laminate, in which at least one surface of at least one of a positive electrode current collector layer and a negative electrode current collector layer has a laminated portion and an extended portion, the surface roughness of the extended portion is greater than the surface roughness of the laminated portion, and the surface roughness of the extended portion is obtained by embossing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7070052 Summary of the Invention [Problem to be solved by the invention]

[0005] The present inventors have been studying a secondary battery in which the thickness of the negative electrode active material layer changes with charging and discharging, and have been studying the provision of a frame material surrounding the negative electrode active material layer in order to prevent the negative electrode active material layer from deforming in the planar direction in such a secondary battery.

[0006] However, in a secondary battery having the above-mentioned configuration, when the thickness of the negative electrode active material layer is reduced, the negative electrode current collector foil arranged on the negative electrode active material layer may interfere with the frame material, and the negative electrode current collector foil may not conform to the negative electrode active material layer. If the negative electrode current collector foil does not conform to the negative electrode active material layer, it becomes difficult to repeatedly charge and discharge the battery.

[0007] Therefore, an object of the present invention is to provide a secondary battery in which a frame material is provided to surround a negative electrode active material layer, and in which a negative electrode current collector foil can follow the negative electrode active material layer even when the thickness is reduced. [Means for solving the problem]

[0008] In one embodiment, the secondary battery according to the present invention includes a solid electrolyte layer, a positive electrode active material layer and a negative electrode active material layer sandwiching the solid electrolyte layer, a negative electrode current collector foil arranged on the negative electrode active material layer, and a frame material arranged on the solid electrolyte layer to surround the negative electrode active material layer. The negative electrode active material layer is configured so that its thickness changes with charging and discharging. When viewed along the stacking direction, the outer peripheral edge of the negative electrode current collector foil is located inside the inner peripheral edge of the frame material. Effect of the Invention

[0009] According to the present invention, there is provided a secondary battery in which a frame material is provided to surround a negative electrode active material layer, and in which the negative electrode current collector foil can follow the negative electrode active material layer even when the thickness is reduced. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a secondary battery according to a first embodiment. [Diagram 2] FIG. 2 is a plan view showing a partial configuration of the secondary battery. [Diagram 3] FIG. 3 is a schematic cross-sectional view showing a secondary battery according to a comparative example. [Figure 4] FIG. 4 is a schematic cross-sectional view showing a secondary battery according to the first modification. [Diagram 5]FIG. 5 is a schematic cross-sectional view showing a secondary battery according to the second modification. [Figure 6] FIG. 6 is a schematic cross-sectional view showing a secondary battery according to the third modification. [Figure 7] FIG. 7 is a table showing the temperatures of the negative electrode active material layers. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0012] (First embodiment) The secondary battery according to this embodiment is a so-called all-solid-state battery.

[0013] In this specification, the term "all-solid-state battery" refers to a secondary battery in which the positive active material layer, the negative active material layer, and the electrolyte layer are substantially composed of solid materials. Here, the "all-solid-state battery" may be any battery in which each layer can be said to be "substantially" solid, and may contain a small amount of liquid material. For example, even if a battery uses a small amount of liquid electrolyte in addition to a solid electrolyte as the electrolyte, it is included in the all-solid-state battery in this specification as long as each layer can be said to be substantially solid.

[0014] Fig. 1 is a schematic cross-sectional view showing a secondary battery 1 according to this embodiment. Fig. 1 shows changes in the configuration due to charging and discharging. Fig. 1(a) shows the configuration in an initial charged state, Fig. 1(b) shows the configuration in a discharged state, and Fig. 1(c) shows the configuration in a recharged state. Fig. 2 is a plan view showing a part of the configuration of the secondary battery 1, as viewed from the negative electrode side.

[0015] As shown in Figs. 1 and 2, the secondary battery 1 has a solid electrolyte layer 2, a positive electrode active material layer 3, a negative electrode active material layer 4, a positive electrode current collector foil 5, a negative electrode current collector foil 6, a frame material 7, and a negative electrode current collector tab 8. The positive electrode active material layer 3 and the negative electrode active material layer 4 are arranged to sandwich the solid electrolyte layer 2 in the stacking direction. The positive electrode current collector foil 5 is arranged on the positive electrode active material layer 3. The negative electrode current collector foil 6 is arranged on the negative electrode active material layer 4. The negative electrode current collector tab 8 is connected to the negative electrode current collector foil 6. Although not shown, a positive electrode current collector tab is connected to the positive electrode current collector foil 5.

[0016] The frame material 7 is disposed on the solid electrolyte layer 2 so as to surround the negative electrode active material layer 4. Specifically, when viewed along the lamination direction, the solid electrolyte layer 2 is larger than the negative electrode active material layer 4. Therefore, an excess area where the negative electrode active material layer 4 is not provided exists on the outer periphery of the solid electrolyte layer 2. The frame material 7 is provided in this excess area. The frame material 7 is provided to suppress deformation of the negative electrode active material layer 4 in the planar direction. For example, when the negative electrode active material layer 4 is made of a flexible material (metallic lithium, etc.), the negative electrode active material layer 4 may deform in the planar direction when excessive pressure is applied during production or operation. The frame material 7 prevents the negative electrode active material layer 4 from deforming more than necessary. In this embodiment, the negative electrode active material layer 4 and the frame material 7 are separated from each other at least in a normal state (a state where excessive pressure is not applied).

[0017] The negative electrode current collector tab 8 is in the form of a sheet. One end of the negative electrode current collector tab 8 is connected to the outer surface of the negative electrode current collector foil 6 (the surface opposite to the surface facing the negative electrode active material layer 4). The negative electrode current collector tab 8 extends from one end to the outside in a direction (plane direction) perpendicular to the stacking direction. Specifically, the negative electrode current collector tab 8 extends from one end so as to cross over the frame material 7 (see FIG. 2).

[0018] The negative electrode active material layer 4 is configured so that its thickness changes with charging and discharging. Specifically, in the secondary battery 1, charging and discharging are performed by the conduction of lithium ions. In a charged state, the negative electrode active material layer 4 contains metallic lithium or a lithium-containing alloy as a negative electrode active material. During discharging, lithium ions move from the negative electrode active material layer 4 to the positive electrode side, and lithium is absorbed in the positive electrode active material layer 3. During discharging, lithium is lost from the negative electrode active material layer 4, so that the volume of the negative electrode active material layer 4 decreases and its thickness also decreases, as shown in FIG. 1(b). On the other hand, during charging, lithium ions move from the positive electrode active material layer 3 to the negative electrode active material layer 4 side, as shown in FIG. 1(c). As a result, lithium is precipitated as metallic lithium in the negative electrode active material layer 4. Alternatively, lithium is absorbed in the negative electrode active material layer 4 as a lithium-containing alloy. During charging, the volume of the negative electrode active material layer 4 increases due to the precipitation or absorption of lithium, and as a result, the thickness increases.

[0019] In this embodiment, when viewed along the stacking direction, the outer peripheral end a of the negative electrode current collector foil 6 is located at the same position as the inner peripheral end b of the frame material 7, or is located inside the inner peripheral end b of the frame material 7. With this configuration, as shown in FIG. 1(b), even if the thickness of the negative electrode active material layer 4 is reduced, the negative electrode current collector foil 6 does not interfere with the frame material 7. Therefore, even if the thickness of the negative electrode active material layer 4 is reduced, the negative electrode current collector foil 6 follows the negative electrode active material layer 4. This makes it possible to repeat charge and discharge.

[0020] The above effects will be described in more detail with reference to a comparative example. FIG. 3 is a schematic cross-sectional view showing a secondary battery 1 according to a comparative example. FIG. 3(a) shows an initial charging state, FIG. 3(b) shows a discharging state, and FIG. 3(c) shows a recharged state. In the secondary battery 1 shown in FIG. 3, when viewed along the stacking direction, the outer peripheral end a of the negative electrode current collector foil 6 is located outside the inner peripheral end b of the frame material 7. In this comparative example, as shown in FIG. 3(b), when the thickness of the negative electrode active material layer 4 decreases during discharging, the negative electrode current collector foil 6 interferes with the frame material 7. Therefore, the negative electrode current collector foil 6 does not follow the volume change of the negative electrode active material layer 4. Therefore, during subsequent charging, lithium ions from the positive electrode active material layer 3 do not move to the negative electrode side (see FIG. 3(c)). That is, charging is not possible. In contrast, as shown in FIG. 1, according to this embodiment, the negative electrode current collector foil 6 follows the volume change of the negative electrode active material layer 4, so that repeated charging and discharging can be performed.

[0021] The above is an outline of this embodiment.

[0022] In this embodiment, as shown in FIG. 1, the negative electrode current collector tab 8 is connected to the outer surface of the negative electrode current collector foil 6. If the negative electrode current collector tab 8 were connected to the inner surface of the negative electrode current collector foil 6 (the surface in contact with the negative electrode active material layer 4), unevenness would be formed on the inner surface of the negative electrode current collector foil 6. As a result, current concentration may occur during charging and discharging. However, according to this embodiment, since the negative electrode current collector tab 8 is connected to the outer surface of the negative electrode current collector foil 6, no unevenness is formed on the inner surface of the negative electrode current collector foil 6. This makes it possible to prevent current concentration and avoid effects on battery performance, such as a short circuit.

[0023] When viewed along the stacking direction, the outer peripheral end a of the negative electrode current collector foil 6 may be located at the same position as the inner peripheral end b of the frame material 7. Even in this case, the negative electrode current collector foil 6 can enter the inside of the frame material 7 while contacting the inner peripheral end b of the frame material 7 at its outer peripheral end a. Therefore, even if the thickness of the negative electrode active material layer 4 is reduced, the negative electrode current collector foil 6 does not interfere with the frame material 7.

[0024] However, preferably, as shown in FIG. 1(a), the outer peripheral end a is located inside the inner peripheral end b. That is, when viewed along the stacking direction, a gap exists between the outer peripheral end a and the inner peripheral end b. With this configuration, a space that allows a volume change of the negative electrode active material layer 4 is formed between the negative electrode current collector foil 6 and the frame material 7. Therefore, even if the negative electrode active material layer 4 expands significantly, the frame material 7 is less likely to be damaged by the negative electrode active material layer 4.

[0025] (Variation 1) Next, Modification 1 will be described. Fig. 4 is a schematic cross-sectional view showing a secondary battery 1 according to Modification 1. Fig. 4(a) shows the configuration in a charged state, and Fig. 4(b) shows the configuration in a discharged state. Note that, unless otherwise specified, the same configuration as in the first embodiment shown in Fig. 1 can be adopted.

[0026] As shown in FIG. 4(a), the thickness of the negative electrode current collector foil 6 is defined as t1. The thickness of the negative electrode active material layer 4 in a fully charged state is defined as t2. Here, the thickness t1 is smaller than the thickness t2. That is, the thickness t1 of the negative electrode current collector foil 6 is smaller than the maximum thickness t2 of the negative electrode active material layer 4. According to this modification, the thickness t1 of the negative electrode current collector foil 6 is smaller than the maximum thickness t2 of the negative electrode active material layer 4, so that the volume required for the negative electrode current collector foil 6 can be reduced. As a result, the energy density of the secondary battery 1 can be improved.

[0027] Moreover, the secondary battery 1 according to this modification is configured so that the negative electrode current collector tab 8 and the frame material 7 do not interfere with each other at all times. Specifically, as shown in FIG. 4(b), the sum of the thickness of the negative electrode active material layer 4 in a fully discharged state (i.e., the minimum thickness of the negative electrode active material layer 4) and the thickness of the negative electrode current collector foil 6 is defined as t3. Also, the thickness of the frame material 7 is defined as t4. In this case, t3 is larger than t4. With this configuration, even when the thickness of the negative electrode active material layer 4 is at its minimum (fully discharged state), the negative electrode current collector tab 8 does not interfere with the frame material 7. Therefore, damage and deformation of the negative electrode current collector tab 8 due to interference between the negative electrode current collector tab 8 and the frame material 7 can be prevented.

[0028] (Variation 2) Next, a description will be given of Modification 2. Fig. 5 is a schematic cross-sectional view showing a secondary battery 1 according to Modification 2. Fig. 5(a) shows the configuration in a charged state, and Fig. 5(b) shows the configuration in a discharged state. Note that, unless otherwise specified, the same configurations as those in the above-described embodiments and modifications can be adopted.

[0029] In this modification, the negative electrode current collector tab 8 is connected to a side surface of the negative electrode current collector foil 6. The negative electrode current collector tab 8 is integral with the negative electrode current collector foil 6. The thickness of the negative electrode current collector tab 8 is smaller than the thickness of the negative electrode current collector foil 6. In particular, the inner surface d of the negative electrode current collector tab 8 is located at a position farther from the solid electrolyte layer 2 than the inner surface c of the negative electrode current collector foil 6. More specifically, as shown in FIG. 5(b), the inner surface d of the negative electrode current collector tab 8 is provided so as to be at the same position as the lower surface of the frame material 7 when the thickness of the negative electrode active material layer 4 is minimized (fully discharged state). Note that the position of the inner surface d in the fully discharged state may be on the outer side of the frame material 7 in the stacking direction. That is, even in the fully discharged state, the frame material 7 and the negative electrode current collector tab 8 may be separated from each other.

[0030] Even if the configuration of this modified example is adopted, the same effects as those of the above-described embodiment and modified examples can be obtained. That is, the negative electrode current collector tab 8 does not necessarily have to be connected to the outer surface of the negative electrode current collector foil 6, and may be connected to a side surface of the negative electrode current collector foil 6. In addition, the negative electrode current collector tab 8 does not necessarily have to be made of a separate member from the negative electrode current collector foil 6, and the two may be formed integrally.

[0031] (Variation 3) Next, Modification 3 will be described. Fig. 6 is a schematic cross-sectional view showing a secondary battery 1 according to Modification 3. Fig. 6(a) shows the configuration in a charged state, and Fig. 6(b) shows the configuration in a discharged state. Note that, unless otherwise specified, the same configuration as in the above-described embodiment and modifications can be adopted.

[0032] 6(a) and (b), in this modification, even under normal circumstances (particularly when no excessive pressure is applied), the negative electrode active material layer 4 and the frame material 7 are in contact with each other. In addition, when viewed along the stacking direction, the area of ​​the negative electrode current collector foil 6 is smaller than the area of ​​the negative electrode active material layer 4.

[0033] Even if the configuration of this modification is adopted, the same effects as those of the above-described embodiment and modification can be obtained. That is, the negative electrode active material layer 4 and the frame material 7 may be separated from each other under normal circumstances as in the example shown in FIG. 1, but may be in contact with each other as in this modification.

[0034] Also, when viewed along the lamination direction, the area of ​​the negative electrode current collector foil 6 may be larger than the area of ​​the negative electrode active material layer 4, but may be smaller than the area of ​​the negative electrode active material layer 4 as in this modified example. However, the area of ​​the negative electrode current collector foil 6 is preferably 90% or more of the area of ​​the negative electrode active material layer 4, and more preferably 95% or more. FIG. 7 is a table showing the temperature of the negative electrode active material layer 4 calculated using the measured value of the electron transfer resistance at the lithium-current collector foil interface. FIG. 7 shows the temperature of the negative electrode active material layer 4 when a current equivalent to 10 C is applied. FIG. 7 shows the results when a Cu foil is used as the negative electrode current collector foil and the results when a SUS foil is used. As shown in FIG. 7, when the area of ​​the negative electrode current collector foil 6 is less than 90% of the area of ​​the negative electrode active material layer 4, the temperature of the negative electrode active material layer 4 increases significantly. On the other hand, when the area of ​​the negative electrode current collector foil 6 is 90% or more of the area of ​​the negative electrode active material layer 4, the temperature increase is suppressed. Therefore, the temperature rise can be suppressed, and thus, for example, when a material with low heat resistance is used for the secondary battery 1 (for example, polyethylene applied to the inside of the exterior material), the material can be prevented from melting.

[0035] (others) Next, other aspects of the secondary battery 1 will be described.

[0036] The solid electrolyte layer 2 is solid and may be made of any material as long as it functions as an electrolyte layer in a secondary battery. The solid electrolyte layer 2 includes, for example, a resin binder and a solid electrolyte dispersed in the resin binder. The solid electrolyte preferably includes a sulfide solid electrolyte. The thickness of the solid electrolyte layer 2 is, for example, 5 to 100 μm.

[0037] The positive electrode active material layer 3 may be formed of a material capable of releasing lithium ions during charging and absorbing lithium ions during discharging. The positive electrode active material layer 3 includes, for example, a resin binder, and a positive electrode active material and a solid electrolyte dispersed in the resin binder. The positive electrode active material is not particularly limited, but for example, an NMC-based positive electrode active material or the like can be used. The thickness of the positive electrode active material layer 3 is, for example, 10 to 1000 μm, preferably 30 to 500 μm.

[0038] The negative electrode active material layer 4 is a layer containing a negative electrode active material. As described above, examples of the negative electrode active material include metallic lithium and lithium-containing alloys. Examples of the lithium-containing alloy include alloys of lithium with silicon, indium, magnesium, aluminum, tin, and the like. The thickness (maximum thickness) of the negative electrode active material layer 4 is, for example, 5 to 60 μm, and preferably 15 to 50 μm.

[0039] The material of the negative electrode current collector foil 6 is not particularly limited. For example, a metal foil containing Cu, SUS foil, or the like can be used as the negative electrode current collector foil 6. A metal foil containing Cu is preferably used as the negative electrode current collector foil 6. Cu may be contained in the negative electrode current collector foil 6 as a Cu layer, or may be contained in the negative electrode current collector foil 6 as an alloy with another metal. The thickness of the negative electrode current collector foil 6 is, for example, 1 to 50 μm, and preferably 5 to 20 μm.

[0040] The frame material 7 may be any material as long as it is insulating. The frame material 7 may be made of, for example, a solid electrolyte, an insulating resin, etc. The thickness of the frame material 7 is, for example, 5 to 60 μm, and preferably 15 to 50 μm.

[0041] There is no particular limitation on the material of the positive electrode current collector foil 5. As the positive electrode current collector foil 5, for example, aluminum foil or the like can be used.

[0042] The use of the secondary battery 1 according to this embodiment is not particularly limited. For example, the secondary battery 1 can be used for an EV (electric vehicle).

[0043] There is no particular limitation on the method for manufacturing the secondary battery 1 according to this embodiment. For example, the secondary battery 1 can be manufactured by the method described below.

[0044] First, a positive electrode active material, a sulfide solid electrolyte, a conductive additive, a binder, and an organic solvent are mixed to prepare a slurry. The prepared slurry is then applied onto a positive electrode current collector foil and dried. In this way, a positive electrode current collector foil on which a positive electrode active material layer is formed is obtained.

[0045] Also, a sulfide solid electrolyte, a binder, and an organic solvent are mixed to obtain a slurry, which is then applied onto a suitable substrate and dried to obtain a solid electrolyte layer.

[0046] Lithium metal is then pressure-bonded to the negative electrode current collector foil with a thickness of, for example, 30 μm. An insulating frame is then placed around the lithium metal. This results in a negative electrode current collector foil on which the negative electrode active material layer and the frame are formed.

[0047] Next, the obtained positive electrode current collector foil, solid electrolyte layer, and negative electrode active material layer are laminated in this order and pressed. This results in a laminate. Thereafter, necessary members such as a current collector tab are connected. This results in a secondary battery 1.

[0048] The present invention has been described above using the embodiments and modifications. Note that the embodiments and modifications described above are not independent of each other, and some of the features may be combined together within a range that does not contradict each other.

[0049] The following is a summary of the representative relationships between the configurations and effects of the present invention.

[0050] (Appendix 1) A secondary battery comprising a solid electrolyte layer 2, a positive electrode active material layer 3 and a negative electrode active material layer 4 sandwiching the solid electrolyte layer 2, a negative electrode current collector foil 6 arranged on the negative electrode active material layer 4, and a frame material 7 arranged on the solid electrolyte layer 2 so as to surround the negative electrode active material layer 4, the negative electrode active material layer 4 being configured so that its thickness changes with charging and discharging, and the outer peripheral end a of the negative electrode current collector foil 6 being located at the same position as the inner peripheral end b of the frame material 7 or being located inside the inner peripheral end b of the frame material 7 when viewed along the stacking direction. With this configuration, even if the thickness of the negative electrode active material layer 4 is reduced, the negative electrode current collector foil 6 does not interfere with the frame material 7. Therefore, the negative electrode current collector foil 6 can be made to follow the volumetric change of the negative electrode active material layer 4, and repeated charging and discharging can be performed.

[0051] (Appendix 2) The secondary battery according to Supplementary Note 1, further comprising a negative electrode current collector tab 8 connected at one end to the negative electrode current collector foil 6 and extending from the one end so as to cross the frame material 7. According to such a configuration, in a secondary battery in which the negative electrode current collector tab 8 is connected to the negative electrode current collector foil 6, the negative electrode current collector foil 6 can follow the volumetric change of the negative electrode active material layer 4, and repeated charging and discharging can be performed.

[0052] (Appendix 3) A secondary battery according to Supplementary Note 2, wherein the negative electrode current collector tab 8 is connected to the outer surface of the negative electrode current collector foil 6. With this configuration, no irregularities are formed on the contact surface of the negative electrode current collector foil 6 with the negative electrode active material layer 4. This makes it possible to avoid effects on cell performance, such as a short circuit in the battery due to current concentration.

[0053] (Appendix 4) A secondary battery according to Appendix 3, wherein a sum t3 of the minimum thickness of the negative electrode active material layer 4 and the thickness of the negative electrode current collector foil 6 is greater than a thickness t4 of the frame material 7. With this configuration, even when the thickness of the negative electrode active material layer 4 is at its minimum, the negative electrode current collector tab 8 does not interfere with the frame material 7. Therefore, damage and deformation of the negative electrode current collector tab 8 due to interference between the negative electrode current collector tab 8 and the frame material 7 can be prevented.

[0054] (Appendix 5) A secondary battery according to Appendix 2, wherein the inner surface of the negative electrode current collector tab 8 is located farther from the solid electrolyte layer 2 than the inner surface of the negative electrode current collector foil 6. Even when such a configuration is adopted, the negative electrode current collector foil 6 can follow the volumetric change of the negative electrode active material layer 4, and repeated charging and discharging can be performed.

[0055] (Appendix 6) A secondary battery according to Appendix 2, wherein the negative electrode current collector tab 8 is connected to a side surface of the negative electrode current collector foil 6. Even when such a configuration is adopted, the negative electrode current collector foil 6 can follow the volumetric change of the negative electrode active material layer 4, and repeated charging and discharging can be performed.

[0056] (Appendix 7) A secondary battery according to any one of appendices 1 to 6, wherein an outer peripheral end a of the negative electrode current collector foil 6 is spaced apart from an inner peripheral end b of the frame material 7 when viewed along the stacking direction. With this configuration, a space that allows a change in volume of the negative electrode active material layer 4 is formed between the negative electrode current collector foil 6 and the frame material 7. Therefore, even if the negative electrode active material layer 4 expands significantly, the frame material 7 is less likely to be damaged by the negative electrode active material layer 4.

[0057] (Appendix 8) The secondary battery according to any one of Supplementary Notes 1 to 7, wherein the area of ​​the negative electrode current collector foil 6 is 90% or more of the area of ​​the negative electrode active material layer 4. With this configuration, it is possible to suppress a temperature rise in the negative electrode active material layer 4 during charging and discharging.

[0058] (Appendix 9) The secondary battery according to any one of Supplementary Notes 1 to 8, wherein the thickness of the negative electrode current collector foil 6 is smaller than the maximum thickness of the negative electrode active material layer 4. With this configuration, the negative electrode current collector foil 6 is thin, so that the cell energy density can be improved.

[0059] (Appendix 10) The secondary battery according to any one of appendices 1 to 9, wherein the negative electrode current collector foil 6 is a metal foil containing Cu. According to such a configuration, in a secondary battery using a metal foil containing Cu as the negative electrode current collector foil, interference between the negative electrode current collector foil 6 and the frame material 7 can be prevented.

[0060] (Appendix 11) A secondary battery according to any one of appendixes 1 to 10, wherein the negative electrode active material layer 4 contains Li metal or a Li-containing alloy. According to such a configuration, in a secondary battery in which the negative electrode active material layer 4 is a layer containing Li metal or a Li-containing alloy, interference between the negative electrode current collector foil 6 and the frame material 7 can be prevented. [Explanation of symbols]

[0061] 1 secondary battery, 2 solid electrolyte layer, 3 positive electrode active material layer, 4 negative electrode active material layer, 5 positive electrode current collecting foil, 6 negative electrode current collecting foil, 7 frame material, 8 negative electrode current collecting tab

Claims

1. A solid electrolyte layer; a positive electrode active material layer and a negative electrode active material layer provided so as to sandwich the solid electrolyte layer; a negative electrode current collector foil disposed on the negative electrode active material layer; a frame provided on the solid electrolyte layer so as to surround the negative electrode active material layer; Equipped with the negative electrode active material layer is configured so that its thickness changes with charging and discharging; When viewed along the stacking direction, an outer peripheral end of the negative electrode current collector foil is located at the same position as an inner peripheral end of the frame material or is located more inward than the inner peripheral end of the frame material. Secondary battery.

2. 2. The secondary battery according to claim 1, Furthermore, a negative electrode current collecting tab connected to the negative electrode current collecting foil at one end and extending from the one end across the frame material; Secondary battery.

3. 3. The secondary battery according to claim 2, One end of the negative electrode current collector tab is connected to the outer surface of the negative electrode current collector foil. Secondary battery.

4. The secondary battery according to claim 3, the sum of the minimum thickness of the negative electrode active material layer and the thickness of the negative electrode current collector foil is greater than the thickness of the frame material; Secondary battery.

5. 3. The secondary battery according to claim 2, an inner surface of the negative electrode current collecting tab is located farther from the solid electrolyte layer than an inner surface of the negative electrode current collecting foil; Secondary battery.

6. 3. The secondary battery according to claim 2, The negative electrode current collecting tab is connected to a side surface of the negative electrode current collecting foil. Secondary battery.

7. 3. The secondary battery according to claim 1, When viewed along the stacking direction, an outer peripheral end of the negative electrode current collector foil and an inner peripheral end of the frame material are separated from each other. Secondary battery.

8. 3. The secondary battery according to claim 1, the area of ​​the negative electrode current collector foil is 90% or more of the area of ​​the negative electrode active material layer; Secondary battery.

9. 3. The secondary battery according to claim 1, The thickness of the negative electrode current collector foil is smaller than the maximum thickness of the negative electrode active material layer. Secondary battery.

10. 3. The secondary battery according to claim 1, The negative electrode current collector foil is a metal foil containing Cu. Secondary battery.

11. 3. The secondary battery according to claim 1, The negative electrode active material layer contains Li metal or a Li-containing alloy. Secondary battery.

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