Secondary battery

Abstract

This secondary battery includes a positive electrode current collector foil, a positive electrode layer, a solid electrolyte layer, a negative electrode intermediate layer, a negative electrode current collector foil, and a first insulating layer disposed on the solid electrolyte layer and configured to block lithium ions. The side surface of the positive electrode layer is inclined such that the width of the positive electrode layer increases toward the positive electrode current collector foil side. The solid electrolyte layer includes an opposing portion and an inclined side surface portion. At least a part of the negative electrode intermediate layer is provided on the opposing portion. At least a part of the first insulating layer is provided on the inclined side surface portion directly or with the negative electrode intermediate layer interposed therebetween. In a region overlapping at least the inclined side surface portion, a space is formed between the negative electrode current collector foil and the first insulating layer.

Description

secondary battery

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

[0002] Secondary batteries using a solid electrolyte layer are known. Among such secondary batteries, there are known ones configured such that metallic lithium is precipitated on the negative electrode during charging. Hereinafter, such secondary batteries may be referred to as Li-precipitation secondary batteries.

[0003] In Li deposition-type secondary batteries, metallic lithium may be deposited at unintended locations. The metallic lithium deposited at unintended locations does not participate in charge and discharge. In other words, it becomes irreversible metallic lithium. Irreversible deposition of metallic lithium should be avoided because it impairs charge and discharge characteristics.

[0004] In relation to the above, Patent Document 1 (JP 2023-62870 A) discloses "an all-solid-state battery comprising: a power generating element in which an anode layer, a solid electrolyte layer, and a cathode layer are laminated in this order; an elastic body covering the outer periphery of the power generating element; an anode current collector in contact with the anode layer; and a cathode current collector in contact with the cathode layer, wherein the solid electrolyte layer covers the surface of the cathode layer formed on the cathode current collector, and wherein, in a cross-sectional view, a first contact point that is located innermost among contact points between the outer periphery of the solid electrolyte layer on the anode layer side and the elastic body is located more inner than a second contact point that is located outermost among contact points between the cathode current collector and the cathode layer."

[0005] In the all-solid-state battery described in Patent Document 1, an elastic body is provided to cover the outer periphery of the power generating element. However, the present inventors have been studying a secondary battery that does not include such an elastic body due to reasons such as manufacturing costs. It is desirable that irreversible deposition of metallic lithium is suppressed in such a secondary battery as well.

[0006] Therefore, an object of the present invention is to provide a Li deposition type secondary battery in which irreversible deposition of metallic lithium is suppressed.

[0007] In one aspect, a secondary battery according to the present invention comprises a positive electrode current collector foil, a positive electrode layer disposed on the positive electrode current collector foil, a solid electrolyte layer disposed on the positive electrode current collector foil so as to cover the positive electrode layer, a negative electrode intermediate layer disposed on the solid electrolyte layer, a negative electrode current collector foil disposed on the negative electrode intermediate layer, and a first insulating layer disposed on the solid electrolyte layer and configured to block lithium ions. During charging, metallic lithium precipitates between the negative electrode intermediate layer and the negative electrode current collector foil. The side surface of the positive electrode layer is inclined so that the width of the positive electrode layer increases toward the positive electrode current collector foil. The solid electrolyte layer comprises a facing portion that covers the top surface of the positive electrode layer and an inclined side surface portion that covers the side surface of the positive electrode layer. At least a portion of the negative electrode intermediate layer is disposed on the facing portion. At least a portion of the first insulating layer is disposed on the inclined side surface portion directly or via the negative electrode intermediate layer. The inner peripheral edge of the first insulating layer is in contact with the outer peripheral edge of the negative electrode intermediate layer or is located inside the outer peripheral edge of the negative electrode intermediate layer. The outer peripheral edge of the negative electrode current collector foil is located outward from the outer peripheral edge of the positive electrode layer, and a space is formed between the negative electrode current collector foil and the first insulating layer at least in the region overlapping with the inclined side surface portion.

[0008] FIG. 1 is a schematic cross-sectional view showing a secondary battery according to a first embodiment. FIG. 2 is a schematic cross-sectional view showing the configuration at an end of a secondary battery according to a reference example. FIG. 3 is a schematic cross-sectional view showing the configuration at an end of a secondary battery according to the first embodiment. FIG. 4 is a schematic cross-sectional view showing a modified example 1. FIG. 5 is a schematic cross-sectional view showing a modified example 2. FIG. 6 is a schematic cross-sectional view showing a modified example 3. FIG. 7 is a schematic cross-sectional view showing a modified example 4. FIG. 8 is a schematic cross-sectional view showing a modified example 5. FIG. 9 is a schematic cross-sectional view showing a modified example 6. FIG. 10 is a schematic cross-sectional view showing a secondary battery according to a second embodiment. FIG. 11 is a schematic cross-sectional view showing a secondary battery according to a third embodiment. FIG. 12 is a diagram for explaining the effects of the fourth embodiment. FIG. 13 is a schematic cross-sectional view showing a secondary battery according to a fifth embodiment.

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0010] (1) First Embodiment Fig. 1 is a schematic cross-sectional view showing a secondary battery 1 according to an embodiment. The secondary battery 1 according to this embodiment is a secondary battery using a solid electrolyte layer as an electrolyte layer. The secondary battery 1 according to this embodiment includes so-called all-solid-state batteries.

[0011] 1 , the secondary battery 1 includes a positive electrode current collector foil 2, a positive electrode layer 3, a solid electrolyte layer 4, a negative electrode intermediate layer 5, a negative electrode current collector foil 7, and a first insulating layer 6. The positive electrode current collector foil 2, the positive electrode layer 3, the solid electrolyte layer 4, the negative electrode intermediate layer 5, and the negative electrode current collector foil 7 are stacked in this order in the stacking direction. The first insulating layer 6 is provided around the negative electrode intermediate layer 5.

[0012] The positive electrode layer 3 is configured to release lithium ions during charging and to absorb lithium ions during discharging. The positive electrode layer 3 is disposed on the positive electrode current collector foil 2. For reasons of manufacturing, the side surface of the positive electrode layer 3 is inclined so that the width of the positive electrode layer 3 increases toward the positive electrode current collector foil 2. In the example shown in FIG. 1 , the side surface of the positive electrode layer 3 has a curved surface that bulges outward. The outer peripheral edge of the positive electrode layer 3 is located inside the outer peripheral edge of the positive electrode current collector foil 2.

[0013] The solid electrolyte layer 4 is configured to conduct lithium ions but not electrons. The solid electrolyte layer 4 is disposed on the positive electrode current collector foil 2 so as to cover the positive electrode layer 3.

[0014] Specifically, the solid electrolyte layer 4 has a facing portion 4-1, an inclined side surface portion 4-2, and an outer peripheral portion 4-3.

[0015] The facing portion 4-1 is a portion that covers the upper surface of the positive electrode layer 3. The facing portion 4-1 faces the negative electrode current collector foil 7 with the negative electrode intermediate layer 5 interposed therebetween.

[0016] The inclined side surface portion 4-2 is a portion that covers the side surface of the positive electrode layer 3. The inclined side surface portion 4-2 is inclined to correspond to the side surface of the positive electrode layer 3. The inclined side surface portion 4-2 extends from the outer peripheral edge of the facing portion 4-1 outward so as to become more distant from the negative electrode current collector foil 7.

[0017] The outer peripheral portion 4-3 is a portion that covers the positive electrode current collector foil 2. The outer peripheral portion 4-3 extends outward from the outer peripheral edge of the inclined side surface portion 4-2.

[0018] The negative electrode intermediate layer 5 is disposed on the solid electrolyte layer 4. In the example shown in Fig. 1, the negative electrode intermediate layer 5 is disposed on the opposing portion 4-1.

[0019] The negative electrode intermediate layer 5 is provided to control the location of deposition of metallic lithium. During charging, metallic lithium is deposited between the negative electrode intermediate layer 5 and the negative electrode current collector foil 7. The negative electrode intermediate layer 5 is conductive and configured to allow lithium ions to pass through.

[0020] The first insulating layer 6 is provided to suppress irreversible deposition of metallic lithium. The first insulating layer 6 is configured to block lithium ions. Furthermore, the first insulating layer 6 has electronic insulating properties. As described above, the first insulating layer 6 is provided around the negative electrode intermediate layer 5. The first insulating layer 6 is disposed between the solid electrolyte layer 4 and the negative electrode current collector foil 7 in the stacking direction. In this embodiment, the first insulating layer 6 is provided directly on the solid electrolyte layer 4, from the inner peripheral edge of the inclined side surface portion 4-2 to a portion of the outer peripheral portion 4-3. That is, when viewed along the stacking direction, the inner peripheral edge of the first insulating layer 6 (see A in the figure) is aligned with the inner peripheral edge of the inclined side surface portion 4-2, and the outer peripheral edge of the first insulating layer 6 (see B in the figure) is located on the outer peripheral portion 4-3. Furthermore, the inner peripheral edge (A) of the first insulating layer 6 contacts the outer peripheral edge of the negative electrode intermediate layer 5. Specifically, the inner peripheral end surface of the first insulating layer 6 and the outer peripheral end surface of the negative electrode intermediate layer 5 are in contact with each other without any gap.

[0021] The thickness of the first insulating layer 6 is generally constant. Therefore, the first insulating layer 6 conforms to the upper surface of the solid electrolyte layer 4 from the inclined side surface portion 4-2 to the outer periphery portion 4-3. That is, the first insulating layer 6 extends from the outer periphery end of the facing portion 4-1 so as to become farther away from the negative electrode current collector foil 7 as it moves outward.

[0022] The negative electrode current collector foil 7 is disposed on the negative electrode intermediate layer 5. In a discharged state, the negative electrode current collector foil 7 is in contact with the negative electrode intermediate layer 5. The outer peripheral edge of the negative electrode current collector foil 7 is located outside the outer peripheral edge of the positive electrode layer 3. The negative electrode current collector foil 7 is disposed on a plane perpendicular to the stacking direction. That is, the negative electrode current collector foil 7 is disposed parallel to the positive electrode current collector foil 2. Unlike the solid electrolyte layer 4, the negative electrode current collector foil 7 does not follow the side surface of the positive electrode layer 3. Therefore, a space is formed between the negative electrode current collector foil 7 and the first insulating layer 6 at least in the region overlapping with the inclined side surface portion 4-2. In the example shown in FIG. 1 , a space is formed between the negative electrode current collector foil 7 and the positive electrode current collector foil 2 in the inclined side surface portion 4-2 and in the region outside thereof.

[0023] In this specification, "a space is formed between the negative electrode current collector foil 7 and the first insulating layer" means that there is an empty area with no object between the negative electrode current collector foil 7 and the first insulating layer 6 at least in part. In other words, this expression does not intend to exclude any configuration between the negative electrode current collector foil 7 and the first insulating layer 6. For example, metallic lithium may be deposited on the negative electrode current collector foil 7 in a portion where the negative electrode current collector foil 7 and the first insulating layer 6 face each other in the stacking direction. In such a case, if metallic lithium is present between the negative electrode current collector foil 7 and the first insulating layer 6 but a space exists between the metallic lithium and the first insulating layer 6, it can be said that "a space is formed between the negative electrode current collector foil and the first insulating layer."

[0024] Although not shown, the secondary battery 1 is compressed in the stacking direction by a pair of end plates disposed on both sides of the secondary battery 1 in the stacking direction.

[0025] The above is the configuration of the secondary battery 1 according to this embodiment. According to this embodiment, irreversible deposition of metallic lithium is suppressed because the first insulating layer 6 is provided. This point will be described with reference to a reference example.

[0026] FIG. 2 is a schematic cross-sectional view showing the configuration of an end portion of a secondary battery 1 according to a reference example. In this reference example, the first insulating layer 6 is not provided. During charging, lithium contained in the positive electrode layer 3 migrates as lithium ions to the negative electrode side through the solid electrolyte layer 4. The lithium ions that migrate to the negative electrode side are precipitated as metallic lithium 8 between the negative electrode intermediate layer 5 and the negative electrode current collector foil 7. The metallic lithium 8 is intended to precipitate in the region overlapping the opposing portion 4-1. However, metallic lithium may also precipitate in the region overlapping the inclined side portion 4-2. The metallic lithium precipitated in such a position does not migrate to the positive electrode layer 3 during discharge. In other words, it becomes irreversible metallic lithium that is not involved in charge and discharge. The irreversible deposition of metallic lithium impairs charge and discharge characteristics.

[0027] 3 is a schematic cross-sectional view showing the configuration of the end portion of the secondary battery 1 according to this embodiment. According to this embodiment, a first insulating layer 6 is provided on the inclined side surface portion 4-2. The first insulating layer 6 is configured to block lithium ions. Therefore, metallic lithium is less likely to deposit on the inclined side surface portion 4-2. Irreversible deposition of metallic lithium is suppressed, and deterioration of charge / discharge characteristics can be prevented.

[0028] Furthermore, according to this embodiment, the inner peripheral edge of the first insulating layer 6 is in contact with the outer peripheral edge of the negative electrode intermediate layer 5. That is, there is no gap between the inner peripheral edge of the first insulating layer 6 and the outer peripheral edge of the negative electrode intermediate layer 5. If a gap exists between the first insulating layer 6 and the negative electrode intermediate layer 5, metallic lithium may precipitate in the gap. Metallic lithium precipitated in the gap may become irreversible metallic lithium. In contrast, according to this embodiment, there is no gap between the first insulating layer 6 and the negative electrode intermediate layer 5, so irreversible precipitation of metallic lithium is more reliably prevented.

[0029] The first embodiment has been briefly described above.

[0030] In this embodiment, the first insulating layer 6 is disposed directly on the solid electrolyte layer 4, from the inner peripheral edge of the inclined side surface portion 4-2 to a portion of the outer peripheral portion 4-3. The first insulating layer 6 is also provided around the negative electrode intermediate layer 5, and its inner peripheral edge is in contact with the outer peripheral edge of the negative electrode intermediate layer. However, the location where the first insulating layer 6 is provided may be any location that can prevent irreversible deposition of metallic lithium, and is not limited to the configuration shown in FIG. 1 . This point will be explained below with reference to modified examples.

[0031] (Variation 1) FIG. 4 is a schematic cross-sectional view showing a secondary battery 1 according to Variation 1. In the example shown in FIG. 4, the boundary (A in FIG. 4) between the first insulating layer 6 and the negative electrode intermediate layer 5 is located on the facing portion 4-1. That is, boundary A is located inside the boundary between the facing portion 4-1 and the inclined side surface portion 4-2. As in this variation, boundary A may be located inside the boundary between the facing portion 4-1 and the inclined side surface portion 4-2, as long as the necessary charge / discharge region is secured. In other words, the negative electrode intermediate layer 5 does not need to completely cover the facing portion 4-1; it is sufficient that it is provided on at least a portion of the facing portion 4-1. Furthermore, the first insulating layer 6 may cover a portion of the outer periphery of the facing portion 4-1. However, charge / discharge does not occur in the portion where the first insulating layer 6 is provided. Therefore, from the viewpoint of securing a sufficient charge / discharge region, it is preferable that the area of ​​the portion where the first insulating layer 6 is provided on the facing portion 4-1 be as small as possible within a controllable range.

[0032] (Variation 2) FIG. 5 is a schematic cross-sectional view showing Variation 2. In this variation, the boundary A between the first insulating layer 6 and the negative electrode intermediate layer 5 is located on the inclined side surface portion 4-2. As in this variation, the boundary A may be located outside the boundary between the opposing portion 4-1 and the inclined side surface portion 4-2. That is, the first insulating layer 6 does not need to cover the entire area of ​​the inclined side surface portion 4-2; it is sufficient that it covers at least a portion of the inclined side surface portion 4-2. Providing the first insulating layer 6 on at least a portion of the inclined side surface portion 4-2 can prevent irreversible deposition of metallic lithium in that portion, thereby achieving a certain effect. Furthermore, as in this variation, the negative electrode intermediate layer 5 may extend so as to cover a portion of the inclined side surface portion 4-2.

[0033] (Variations 3 to 5) FIGS. 6 to 8 are schematic cross-sectional views showing secondary batteries 1 according to variations 3 to 5 of this embodiment, respectively. In all of the variations shown in FIGS. 6 to 8, the inner peripheral edge of the first insulating layer 6 is located inside the outer peripheral edge of the negative electrode intermediate layer 5. That is, the first insulating layer 6 and the negative electrode intermediate layer 5 partially overlap at their boundary. In the example shown in FIG. 6, the outer peripheral edge of the negative electrode intermediate layer 5 overlaps the inner peripheral edge of the first insulating layer 6. In the example shown in FIG. 7, the inner peripheral edge of the first insulating layer 6 overlaps the outer peripheral edge of the negative electrode intermediate layer 5. In the example shown in FIG. 8, the outer peripheral edge of the negative electrode intermediate layer 5 is sandwiched between the inner peripheral edges of the first insulating layer 6.

[0034] As in the modified examples shown in FIGS. 6 to 8 , the inner peripheral edge of the first insulating layer 6 may be located inside the outer peripheral edge of the negative electrode intermediate layer 5. Even when such a configuration is adopted, there is no gap between the first insulating layer 6 and the negative electrode intermediate layer 5. Therefore, irreversible deposition of metallic lithium in the gap can be prevented. In addition, the configurations according to these modified examples do not require high alignment precision during manufacturing compared to when the inner peripheral edge of the first insulating layer 6 and the outer peripheral edge of the negative electrode intermediate layer 5 are in contact. Therefore, manufacturing difficulty does not increase.

[0035] (Variation 6) Figure 9 is a schematic cross-sectional view showing a secondary battery 1 according to Variation 6. In this variation, at least a portion of the negative electrode intermediate layer 5 is provided on the inclined side surface portion 4-2. A first insulating layer 6 is provided on the negative electrode intermediate layer 5. More specifically, the negative electrode intermediate layer 5 is disposed so as to cover not only the facing portion 4-1 but also a portion of the inclined side surface portion 4-2 and the outer circumferential portion 4-3. The first insulating layer 6 is disposed on the negative electrode intermediate layer 5 from the inner peripheral edge of the inclined side surface portion 4-2 to a portion of the outer circumferential portion 4-3.

[0036] As in this modification, the first insulating layer 6 may be disposed on the solid electrolyte layer 4 via the negative electrode intermediate layer 5. Even when such a configuration is adopted, the lithium ions are blocked in the portion where the first insulating layer 6 is provided, so that irreversible deposition of metallic lithium can be suppressed.

[0037] Furthermore, in this modification, as in modifications 3 to 5 (FIGS. 6 to 8), the inner peripheral edge of the first insulating layer 6 can be said to be located inside the outer peripheral edge of the negative electrode intermediate layer 5. In other words, no gap is formed between the first insulating layer 6 and the negative electrode intermediate layer 5, preventing irreversible deposition of metallic lithium in such a gap. Furthermore, compared to when the inner peripheral edge of the first insulating layer 6 and the outer peripheral edge of the negative electrode intermediate layer 5 are in contact, high alignment precision is not required during manufacturing. Therefore, manufacturing difficulty does not increase.

[0038] (Position of Outer Peripheral Edge of First Insulating Layer) Next, the position of the outer peripheral edge of the first insulating layer 6 will be described. The position of the outer peripheral edge of the first insulating layer 6 is not particularly limited. Preferably, as shown in FIG. 1, the outer peripheral edge of the first insulating layer 6 (see end B in FIG. 1) is located inside the outer peripheral edge of the outer peripheral portion 4-3 (the outer peripheral edge of the entire solid electrolyte layer 4) when viewed along the stacking direction. With this configuration, the first insulating layer 6 can be omitted in locations where irreversible metallic lithium is unlikely to precipitate. This can reduce the weight of the first insulating layer 6, which is advantageous from the perspective of weight energy density.

[0039] (2) Second Embodiment Next, a second embodiment will be described. Detailed description will be omitted for the points where the same configuration as the above-described embodiment can be adopted.

[0040] 10 is a schematic cross-sectional view showing a secondary battery 1 according to the second embodiment. In this embodiment, the thickness of the first insulating layer 6 is smaller than the thickness of the negative electrode intermediate layer 5.

[0041] In a secondary battery 1 using a solid electrolyte layer, the charge / discharge region (the region corresponding to the facing portion 4-1) needs to be pressurized in the stacking direction to obtain good charge / discharge characteristics. If the thickness of the first insulating layer 6 were greater than the thickness of the negative electrode intermediate layer 5, the first insulating layer 6 would act as an obstacle, and sufficient pressure might not be applied to the charge / discharge region (the region overlapping the facing portion 4-1). In contrast, according to this embodiment, the thickness of the first insulating layer 6 is smaller than the thickness of the negative electrode intermediate layer 5, so the first insulating layer 6 does not interfere with the application of pressure. Therefore, it is possible to apply uniform pressure to the secondary battery 1.

[0042] (3) Third Embodiment Next, a third embodiment will be described. Detailed description will be omitted for the points where the same configuration as the above-described embodiments can be adopted.

[0043] 11 is a schematic cross-sectional view showing a secondary battery 1 according to a third embodiment. In this embodiment, the height of the upper surface of the first insulating layer 6 (meaning the distance from the positive electrode current collector foil 2) is equal to or less than the height of the upper surface of the negative electrode intermediate layer 5. By adopting such a configuration, as in the second embodiment, the first insulating layer 6 does not prevent pressure from being applied to the charge / discharge region. Therefore, it is possible to apply pressure uniformly to the secondary battery 1.

[0044] (4) Fourth Embodiment Next, a fourth embodiment will be described. Detailed description will be omitted for the points where the same configuration as the above-described embodiments can be adopted.

[0045] In this embodiment, the first insulating layer 6 has a higher elastic modulus than metallic lithium. In this specification, the term "elastic modulus" refers to Young's modulus.

[0046] FIG. 12 is a diagram illustrating the effects of this embodiment. As described above, the provision of the first insulating layer 6 suppresses irreversible deposition of metallic lithium. However, some irreversible metallic lithium may precipitate in the region outside the opposing portion 4-1. In particular, metallic lithium may precipitate on the negative electrode current collector foil 7 in the region facing the inclined side surface portion 4-2. Here, the negative electrode current collector foil 7 may bend due to an external force or the like. As a result, metallic lithium may come into contact with the first insulating layer 6 and break through the first insulating layer 6. However, according to this embodiment, the elastic modulus of the first insulating layer 6 is higher than that of metallic lithium, making it difficult for metallic lithium to break through the first insulating layer 6. Therefore, destruction of the first insulating layer 6 due to contact with metallic lithium is prevented.

[0047] (5) Fifth Embodiment Next, a fifth embodiment will be described. Detailed description will be omitted for the fact that the same configuration as the above-described embodiments can be adopted.

[0048] 13 is a schematic cross-sectional view showing a secondary battery 1 according to a fifth embodiment. In this embodiment, a second insulating layer 9 is added. The second insulating layer 9 is provided on the negative electrode current collector foil 7. The second insulating layer 9 is adhered to the surface of the negative electrode current collector foil 7 facing the positive electrode current collector foil 2. Like the first insulating layer 6, the second insulating layer 9 is configured to block lithium ions. Furthermore, the second insulating layer 9 has electronic insulation properties.

[0049] When viewed along the stacking direction, the inner peripheral edge of the second insulating layer 9 is located outside the outer peripheral edge of the facing portion 4-1. That is, when viewed along the stacking direction, the inner peripheral edge of the second insulating layer 9 is located away from the outer peripheral edge of the facing portion 4-1. In the example shown in FIG. 13 , the inner peripheral edge of the second insulating layer 9 is located at a position that roughly corresponds to the outer peripheral edge of the inclined side surface portion 4-2. Furthermore, when viewed along the stacking direction, the outer peripheral edge of the second insulating layer 9 is located outside the outer peripheral edge of the first insulating layer 6.

[0050] According to this embodiment, irreversible deposition of metallic lithium is more reliably prevented by providing the second insulating layer 9. Furthermore, since the second insulating layer 9 is disposed further outward than the outer peripheral edge of the facing portion 4-1, it is less likely to become an obstacle when pressure is applied to the charge / discharge region.

[0051] (6) Materials of Each Layer, etc. The configurations of the first to fifth embodiments have been described above. Next, the materials constituting each layer included in the secondary battery 1 according to the above-described embodiments will be specifically described.

[0052] (Positive Electrode Layer) The positive electrode layer may be formed of a material that can release lithium ions during charging and absorb lithium ions during discharging. The positive electrode layer may be formed of a material containing, for example, a resin binder and a positive electrode active material dispersed in the resin binder. For example, a lithium metal composite oxide may be used as the positive electrode active material. For example, the lithium metal composite oxide may be LiCoO ２ , LiMnO ２ , LiNiO ２ , LiVO ２ , and Li(Ni—Mn—Co)O ２ Layered rock salt compounds such as LiMn２ O ４ , and LiNi ０．５ Mn １．５ O ４ spinel-type compounds such as LiFePO ４ , and LiMnPO ４ Olivine type compounds such as Li ２ FeSiO ４ , and Li ２ MnSiO ４ In addition, Li ４ Ti ５ O １２ The thickness of the positive electrode layer is, for example, 10 to 500 μm, and preferably 50 to 200 μm.

[0053] (Solid Electrolyte Layer) The solid electrolyte layer 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 may include, 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 is, for example, 5 to 100 μm.

[0054] (Negative Electrode Intermediate Layer) As described above, the negative electrode intermediate layer is a layer configured to deposit metallic lithium between the negative electrode intermediate layer and the negative electrode current collector foil. The negative electrode intermediate layer is formed, for example, by a layer containing metal particles such as silver and carbon particles such as carbon black. These particles may be dispersed in a binder resin. The thickness of the negative electrode intermediate layer is preferably thinner than the thickness of the metallic lithium deposited in a charged state. The thickness of the negative electrode intermediate layer is, for example, 0.1 to 50 μm, preferably 0.5 to 30 μm.

[0055] (Negative electrode current collector foil and positive electrode current collector foil) The negative electrode current collector foil and positive electrode current collector foil are not particularly limited. For example, the negative electrode current collector foil may be a thin film of copper, a copper alloy, nickel, a nickel alloy, or the like. The positive electrode current collector foil may be, for example, an aluminum foil.

[0056] (First Insulating Layer and Second Insulating Layer) The first insulating layer and the second insulating layer may have lithium ion blocking properties and electronic insulating properties. For example, a resin material and an inorganic material such as alumina may be used as the constituent material of the first insulating layer and the second insulating layer. The thickness of each of the first insulating layer and the second insulating layer is, for example, 0.1 to 100 μm, preferably 0.2 to 30 μm, and more preferably 0.5 to 20 μm.

[0057] [Addendum] The main aspects and effects of the present invention are summarized below as appendices.

[0058] (Note 1) A battery comprising a positive electrode current collector foil (2), a positive electrode layer (3) disposed on the positive electrode current collector foil (2), a solid electrolyte layer (4) disposed on the positive electrode current collector foil (2) so as to cover the positive electrode layer (3), a negative electrode intermediate layer (5) disposed on the solid electrolyte layer (4), a negative electrode current collector foil (7) disposed on the negative electrode intermediate layer (5), and a first insulating layer (6) disposed on the solid electrolyte layer (4) and configured to block lithium ions, wherein during charging, metallic lithium precipitates between the negative electrode intermediate layer (5) and the negative electrode current collector foil (7), the side of the positive electrode layer (3) is inclined so that the width of the positive electrode layer (3) increases toward the positive electrode current collector foil (2), and the solid electrolyte layer (4) has an opposing portion (4-1) which is a portion covering the upper surface of the positive electrode layer (3), and an inclined side surface portion (4-2) that covers the side surface of the positive electrode layer (3), at least a portion of the negative electrode intermediate layer (5) is provided on the facing portion (4-1), at least a portion of the first insulating layer (6) is provided on the inclined side surface portion (4-2) directly or via the negative electrode intermediate layer (5), the inner peripheral edge of the first insulating layer (6) is in contact with the outer peripheral edge of the negative electrode intermediate layer (5) or is located more inward than the outer peripheral edge of the negative electrode intermediate layer (5), the outer peripheral edge of the negative electrode current collector foil (7) is located more outward than the outer peripheral edge of the positive electrode layer (3), and a space is formed between the negative electrode current collector foil (7) and the first insulating layer (6) at least in a region overlapping with the inclined side surface portion (4-2).

[0059] According to the above-described configuration, the first insulating layer 6 is provided on the inclined side surface portion 4-2, so that irreversible deposition of metallic lithium on the inclined side surface portion 4-2 is suppressed.

[0060] (Supplementary Note 2) The secondary battery according to Supplementary Note 1, wherein the thickness of the first insulating layer 6 is equal to or less than the thickness of the negative electrode intermediate layer.

[0061] According to the above-described configuration, the first insulating layer 6 does not hinder the application of pressure to the charge / discharge region, so that the secondary battery 1 can be pressurized uniformly.

[0062] (Supplementary Note 3) The secondary battery according to Supplementary Note 1 or 2, wherein the height of the upper surface of the first insulating layer 6 is equal to or lower than the height of the upper surface of the negative electrode intermediate layer 5.

[0063] According to the above-described configuration, the first insulating layer 6 does not hinder the application of pressure to the charge / discharge region, so that the secondary battery 1 can be pressurized uniformly.

[0064] (Appendix 4) The secondary battery according to any one of Appendices 1 to 3, wherein, when viewed along the stacking direction, the first insulating layer 6 is disposed outside the negative electrode intermediate layer 5, and the first insulating layer 6 and the negative electrode intermediate layer 5 partially overlap.

[0065] With this configuration, it is not necessary to precisely control the positions of the first insulating layer 6 and the negative electrode intermediate layer 5, which reduces the difficulty of manufacturing.

[0066] (Supplementary Note 5) The secondary battery according to any one of Supplementary Notes 1 to 4, wherein the first insulating layer 6 has a higher elastic modulus than metallic lithium.

[0067] With this configuration, even if metallic lithium is deposited at a position facing the first insulating layer 6, the deposited metallic lithium can be prevented from breaking through the first insulating layer 6.

[0068] (Appendix 6) The secondary battery according to any one of Appendices 1 to 5, wherein the solid electrolyte layer 4 further includes an outer peripheral portion 4-3 that covers the positive electrode current collector foil 2 and extends outward from the outer peripheral edge of the inclined side surface portion 4-2, and when viewed along the stacking direction, the outer peripheral edge of the first insulating layer 6 is located more inward than the outer peripheral edge of the outer peripheral portion 4-3.

[0069] According to this configuration, the first insulating layer 6 is omitted in areas where irreversible deposition of metallic lithium is unlikely, so that the weight energy density can be increased.

[0070] (Appendix 7) The secondary battery according to any one of Appendices 1 to 6, further comprising: a second insulating layer 9 bonded to a surface of the negative electrode current collector foil 7 facing the positive electrode current collector foil 2 and configured to block lithium ions; and when viewed along the stacking direction, an inner peripheral edge of the second insulating layer 9 is positioned outward from an outer peripheral edge of the opposing portion 4-1.

[0071] According to this configuration, the presence of the second insulating layer 9 can more reliably prevent irreversible deposition of metallic lithium.

[0072] (Appendix 8) The secondary battery according to appendix 1, wherein at least a portion of the negative electrode intermediate layer 5 is provided on the inclined side surface portion 4-2, and the first insulating layer 6 is provided on the negative electrode intermediate layer 5.

[0073] With this configuration, it is not necessary to precisely control the positions of the first insulating layer 6 and the negative electrode intermediate layer 5, which reduces the difficulty of manufacturing.

Claims

1. A battery comprising: a positive electrode current collector foil; a positive electrode layer disposed on the positive electrode current collector foil; a solid electrolyte layer disposed on the positive electrode current collector foil so as to cover the positive electrode layer; a negative electrode intermediate layer disposed on the solid electrolyte layer; a negative electrode current collector foil disposed on the negative electrode intermediate layer; and a first insulating layer disposed on the solid electrolyte layer and configured to block lithium ions, wherein during charging, metallic lithium precipitates between the negative electrode intermediate layer and the negative electrode current collector foil, the side surface of the positive electrode layer is inclined so that the width of the positive electrode layer increases toward the positive electrode current collector foil, the solid electrolyte layer comprises: a facing portion that covers the top surface of the positive electrode layer; and an inclined side surface portion that covers the side surface of the positive electrode layer, at least a portion of the negative electrode intermediate layer is provided on the facing portion, and at least a portion of the first insulating layer is provided on the inclined side surface portion directly or via the negative electrode intermediate layer, an inner peripheral edge of the first insulating layer is in contact with an outer peripheral edge of the negative electrode intermediate layer or is located more inward than the outer peripheral edge of the negative electrode intermediate layer; an outer peripheral edge of the negative electrode current collector foil is located more outward than the outer peripheral edge of the positive electrode layer; and a space is formed between the negative electrode current collector foil and the first insulating layer at least in a region overlapping with the inclined side surface portion.

2. The secondary battery according to claim 1, wherein the thickness of the first insulating layer is equal to or less than the thickness of the negative electrode intermediate layer.

3. A secondary battery according to claim 1 or 2, wherein the height of the upper surface of said first insulating layer is equal to or lower than the height of the upper surface of said negative electrode intermediate layer.

4. A secondary battery according to claim 1 or 2, wherein, when viewed along the stacking direction, the first insulating layer is disposed outside the negative electrode intermediate layer, and the first insulating layer and the negative electrode intermediate layer partially overlap.

5. A secondary battery according to claim 1 or 2, wherein the first insulating layer has a higher elastic modulus than metallic lithium.

6. A secondary battery according to claim 1 or 2, wherein the solid electrolyte layer further comprises an outer peripheral portion that covers the positive electrode current collector foil and extends outward from the outer peripheral edge of the inclined side surface portion, and when viewed along the stacking direction, the outer peripheral edge of the first insulating layer is located more inward than the outer peripheral edge of the outer peripheral portion.

7. A secondary battery as defined in claim 1 or 2, further comprising a second insulating layer bonded to the surface of the negative electrode current collector foil facing the positive electrode current collector foil and configured to block lithium ions, wherein when viewed along the stacking direction, the inner peripheral edge of the second insulating layer is positioned outside the outer peripheral edge of the opposing portion.

8. A secondary battery according to claim 1 or 2, wherein at least a portion of the negative electrode intermediate layer is provided on the inclined side surface portion, and the first insulating layer is provided on the negative electrode intermediate layer.

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