All-solid-state battery

Abstract

This all-solid-state battery comprises: a battery cell with a positive electrode layer, a solid electrolyte layer, and a negative electrode layer; positive and negative current-collecting foils; and positive and negative electrode tabs. The solid electrolyte layer has a support and a solid electrolyte supported on the support. The elongation percentage of the support in a tab direction is lower than the elongation percentage of the support in a non-tab direction.

Description

All solid state battery

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

[0002] An all-solid-state battery is a secondary battery that uses a solid electrolyte. A typical all-solid-state battery has a solid electrolyte layer containing a solid electrolyte and electrode layers arranged to sandwich the solid electrolyte layer. One of the challenges facing all-solid-state batteries is improving the strength of the solid electrolyte layer.

[0003] In relation to the above, for example, Patent Document 1 (JP 2021-533542 A) discloses a method for producing a solid electrolyte membrane for an all-solid-state battery, which includes a step of forcing a predetermined solid electrolyte material into the inside of a porous substrate.

[0004] Incidentally, in all-solid-state batteries, tabs are sometimes used for electrical connection with external devices. Specifically, a current collecting foil is placed on an electrode layer. Then, a tab is connected to the end of the current collecting foil by welding or the like. At this time, the current collecting foil may be pulled toward the connection portion with the tab. As a result, a force that pulls the solid electrolyte layer toward the tab may be applied via the current collecting foil, electrode layer, etc. When such a force is applied to the solid electrolyte layer, solid electrolyte particles may fall off. Falling off of solid electrolyte particles should be avoided.

[0005] Therefore, an object of the present invention is to provide an all-solid-state battery that can prevent solid electrolyte particles from falling off.

[0006] In one aspect, the all-solid-state battery according to the present invention includes a battery cell having a positive electrode layer, a solid electrolyte layer, and a negative electrode layer stacked along a stacking direction; a positive electrode current collector foil and a negative electrode current collector foil arranged to sandwich the battery cell; and a positive electrode tab and a negative electrode tab connected to the positive electrode current collector foil and the negative electrode current collector foil, respectively. A tab direction and a non-tab direction are defined as directions perpendicular to the stacking direction. The tab direction is perpendicular to the non-tab direction. The positive electrode current collector foil and the negative electrode current collector foil are connected to the positive electrode tab and the negative electrode tab, respectively, at their ends in the tab direction. The solid electrolyte layer includes a sheet-like support and a solid electrolyte supported by the support. The elongation of the support in the tab direction is smaller than the elongation of the support in the non-tab direction.

[0007] In another aspect, an all-solid-state battery according to the present invention includes a battery cell having a positive electrode layer, a solid electrolyte layer, and a negative electrode layer stacked along a stacking direction; a positive electrode current collector foil and a negative electrode current collector foil arranged to sandwich the battery cell; and a positive electrode tab and a negative electrode tab connected to the positive electrode current collector foil and the negative electrode current collector foil, respectively. A tab direction and a non-tab direction are defined as directions perpendicular to the stacking direction. The tab direction is perpendicular to the non-tab direction. The positive electrode current collector foil and the negative electrode current collector foil are connected to the positive electrode tab and the negative electrode tab, respectively, at their ends in the tab direction. The solid electrolyte layer includes a solid electrolyte and short fibers dispersed in the solid electrolyte layer. The short fibers extend along an extension direction when viewed along the stacking direction. The angle formed between the extension direction and the tab direction is less than 45°.

[0008] FIG. 1 is a schematic cross-sectional view showing an all-solid-state battery according to a first embodiment. FIG. 2 is a plan view showing an all-solid-state battery according to the first embodiment. FIG. 3A is a schematic view showing a reference example. FIG. 3B is a schematic view showing a configuration of a solid electrolyte layer in the first embodiment. FIG. 4 is a schematic view showing a modified example 1. FIG. 5 is a schematic view showing a modified example 2. FIG. 6 is a plan view showing a configuration of a solid electrolyte layer in the second embodiment. FIG. 7A is a schematic view showing a reference example. FIG. 7B is a schematic view showing the tab direction, non-tab direction, and extension direction of short fibers in the second embodiment. FIG. 8 is a schematic view showing a modified example 3. FIG. 9 is a schematic cross-sectional view showing an all-solid-state battery according to a third embodiment. FIG. 10 is a plan view showing an all-solid-state battery according to a fourth embodiment. FIG. 11 is a plan view showing an all-solid-state battery according to a fifth embodiment. FIG. 12 is a plan view showing an all-solid-state battery according to a sixth embodiment. FIG. 13 is a plan view showing an all-solid-state battery according to a seventh embodiment.

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

[0010] In this specification, the term "all-solid-state battery" refers to a secondary battery in which the electrolyte layer and electrode layers (positive electrode layer and negative electrode layer) are substantially solid. Each layer may be "substantially" solid, and a small amount of liquid material may be used.

[0011] First Embodiment Fig. 1 is a schematic cross-sectional view showing an all-solid-state battery 1 according to this embodiment. The all-solid-state battery 1 includes a battery cell 2, a positive electrode current collector foil 6, a negative electrode current collector foil 7, an exterior material 8, a positive electrode tab 9, and a negative electrode tab 10. The battery cell 2 includes a solid electrolyte layer 3, a positive electrode layer 4, and a negative electrode layer 5. The solid electrolyte layer 3 is sandwiched between the positive electrode layer 4 and the negative electrode layer 5. The positive electrode current collector foil 6 and the negative electrode current collector foil 7 are arranged to sandwich the battery cell 2. The positive electrode current collector foil 6 is arranged on the positive electrode layer 4, and the negative electrode current collector foil 7 is arranged on the negative electrode layer 5.

[0012] 1, there are provided a plurality of battery cells 2, a plurality of positive electrode current collector foils 6, and a plurality of negative electrode current collector foils 7. Specifically, the plurality of battery cells 2 are stacked in the stacking direction with the positive electrode current collector foils 6 or the negative electrode current collector foils 7 interposed therebetween.

[0013] The exterior material 8 is provided to protect the battery cells 2. The exterior material 8 is formed from a pair of films. The pair of films are arranged to sandwich a laminate consisting of the battery cells 2, positive electrode current collector foil 6, and negative electrode current collector foil 7.

[0014] The positive electrode tab 9 and the negative electrode tab 10 are provided to connect the positive electrode current collector foil 6 and the negative electrode current collector foil 7 to an external device. One end of the positive electrode tab 9 is disposed inside the exterior case 8, and the other end is located outside the exterior case 8. The plurality of positive electrode current collector foils 6 are connected to one end of the positive electrode tab 9. Similarly, one end of the negative electrode tab 10 is disposed inside the exterior case 8, and the other end of the negative electrode tab 10 is located outside the exterior case 8. The plurality of negative electrode current collector foils 7 are connected to one end of the negative electrode tab 10. The positive electrode current collector foil 6 and the negative electrode current collector foil 7 are connected to the positive electrode tab 9 and the negative electrode tab 10 by, for example, welding.

[0015] Next, the arrangement of the tabs (positive electrode tab 9 and negative electrode tab 10) will be described. Fig. 2 is a plan view schematically showing the all-solid-state battery 1. Fig. 2 shows the arrangement of the solid electrolyte layer 3, current collector foils (positive electrode current collector foil 6 and negative electrode current collector foil 7), and tabs (positive electrode tab 9 and negative electrode tab 10) when viewed along the stacking direction.

[0016] 2, the tab direction and the non-tab direction are defined as directions perpendicular to the stacking direction. The tab direction and the non-tab direction are perpendicular to each other.

[0017] The tab direction is the direction in which the tabs are provided. That is, the positive electrode current collector foil 6 and the negative electrode current collector foil 7 are connected to the positive electrode tab 9 and the negative electrode tab 10 at their ends in the tab direction.

[0018] In addition, when each current collector foil has at least one side and a tab is connected to that side, the tab direction can also be said to be a direction perpendicular to the stacking direction and perpendicular to the side to which the tab is connected. In the example shown in Figure 2, the positive electrode current collector foil 6 and the negative electrode current collector foil 7 are each rectangular. The positive electrode current collector foil 6 and the negative electrode current collector foil 7 are connected to a positive electrode tab 9 and a negative electrode tab 10 at two opposing short sides. In this case, the tab direction is a direction perpendicular to the short side, i.e., a direction along the long side.

[0019] In the example shown in FIG. 2 , the positive electrode tab 9 and the negative electrode tab 10 are arranged in positions that sandwich each current collector foil (6, 7) in the tab direction. That is, the positive electrode tab 9 and the negative electrode tab 10 are connected to two opposing sides. However, the positive electrode tab 9 and the negative electrode tab 10 may be arranged on the same side in the tab direction. That is, when viewed along the stacking direction, the positive electrode tab 9 and the negative electrode tab 10 may be connected to the same side of each current collector foil.

[0020] Next, the configuration of the solid electrolyte layer 3 will be described. The solid electrolyte layer 3 has a support 11 and a solid electrolyte supported by the support 11. The solid electrolyte is a powder and is not self-supporting by itself. On the other hand, the support 11 is self-supporting and in the form of a sheet. By using the support 11, the solid electrolyte layer 3 can be handled as a self-supporting membrane.

[0021] As described above, a tensile force is likely to be applied to the solid electrolyte layer 3 toward the connection portion between the tab and the current collector foil. That is, a tensile force is likely to be applied along the tab direction. Therefore, in the solid electrolyte layer 3, the support 11 is designed to be configured so that the solid electrolyte is unlikely to fall off even when a tensile force is applied along the tab direction. This point will be described below.

[0022] The support 11 has different elongation rates depending on the direction. Specifically, the elongation rate of the support 11 in the tab direction is smaller than the elongation rate of the support 11 in the non-tab direction. The elongation rate of the support 11 can be determined, for example, by applying a certain tensile load to a sample and measuring the length before and after applying the load.

[0023] More specifically, the support 11 contains a plurality of long fibers. As shown in FIG. 2 , the plurality of long fibers are arranged in a mesh pattern so as to form diamond-shaped voids. Here, the direction in which the diamond-shaped voids extend is referred to as the "extension direction." The extension direction is aligned with the tab direction. With this configuration, the support 11 is less likely to extend in the tab direction and more likely to extend in the non-tab direction. In other words, the elongation rate of the support 11 in the tab direction is smaller than the elongation rate of the support 11 in the non-tab direction.

[0024] According to this embodiment, by adopting the above-described configuration, it is possible to prevent the solid electrolyte from falling off. This point will be explained with reference to a reference example.

[0025] 3A is a schematic diagram showing a reference example, illustrating the configuration of the solid electrolyte layer 3. In this reference example, unlike the present embodiment, the pores 13 of the support 11 extend in the non-tab direction. Therefore, the elongation rate of the support 11 is large in the tab direction and small in the non-tab direction.

[0026] As described above, a tensile force is likely to be applied to the solid electrolyte layer 3 in the tab direction. In this modification, the support 11 is likely to stretch in the tab direction, and therefore, when a tensile force is applied in the tab direction, the support 11 stretches, and stress is likely to be applied between the solid electrolyte particles 12. As a result, the solid electrolyte is likely to fall off.

[0027] 3B is a schematic diagram showing the configuration of the solid electrolyte layer 3 in this embodiment. In this embodiment, even if a tensile force is applied in the tab direction, the support 11 is unlikely to deform. That is, in the solid electrolyte layer 3, stress is generated mainly in the support 11, and stress is unlikely to be applied between the solid electrolyte particles 12. Therefore, the solid electrolyte is unlikely to fall off.

[0028] The above is an outline of this embodiment. That is, according to this embodiment, the support 11 is arranged so that the elongation rate in the tab direction is small, so that the solid electrolyte can be prevented from falling off the support 11.

[0029] In this embodiment, the elongation of not only the support 11 but also the entire solid electrolyte layer 3 is small in the tab direction and large in the non-tab direction. This configuration can be said to prevent the solid electrolyte from falling off.

[0030] (Regarding the extension direction of the holes) Next, the extension direction will be described. As described above, the "extension direction" is the direction in which the holes provided in the support 11 extend when viewed along the stacking direction. The extension direction of the holes means the direction in which the length of the holes is the longest. In the example shown in FIG. 2, the holes are rhombic. Therefore, it can be said that the direction in which the longer of the two diagonals of the rhombic holes extends is the "extension direction".

[0031] In the example shown in FIG. 2 , the extension direction is aligned with the tab direction. However, the extension direction does not need to be aligned perfectly with the tab direction and may be slightly offset from the tab direction. This point will be described with reference to Modification 1. FIG. 4 is a schematic diagram showing Modification 1, illustrating the relationship between the extension direction, tab direction, and non-tab direction. As shown in FIG. 4 , in this modification, the extension direction of the holes is offset from the tab direction. As shown in FIG. 4 , the angle formed between the tab direction and the extension direction is defined as θ. The angle θ is less than 45°. If θ is less than 45°, the elongation of the support 11 in the tab direction is smaller than the elongation of the support in the non-tab direction. Therefore, even if the extension direction does not completely match the tab direction, a certain effect can be achieved in preventing the solid electrolyte from falling off. θ is preferably within 10°.

[0032] In the examples shown in Figures 2 and 4, multiple voids are formed in the support 11, and all of the voids extend in the same direction. However, it is not necessary for all of the voids in the support 11 to face the same direction. When voids extending in different directions exist, the average direction in which the voids extend can be considered the extension direction. For example, the support 11 is observed using a microscope or the like from the stacking direction. Then, for each void, a straight line that intersects with the void and has the longest distance between the intersections with the periphery of the void is determined, and the extension direction of the determined straight line is determined as the "void extension direction." Note that if the void has a curved shape (e.g., L-shaped), three or more intersections between the void and the line may be formed. In such cases, the extension direction of the line that has the longest distance between the outermost intersections is determined as the "void extension direction." Then, the "void extension direction" is determined for 50 voids, and the number average of the determined directions is calculated to determine the extension direction. If the angle between the average extension direction and the tab direction thus determined is smaller than 45°, a certain degree of effect can be achieved in preventing the solid electrolyte from falling off.

[0033] (Configuration of Support Body) In the above embodiment, the support body 11 has long fibers and has diamond-shaped pores. Examples of the support body 11 having such long fibers include woven fabric and nonwoven fabric.

[0034] However, the configuration of the support 11 and the shape of the holes are not limited to those described above. This point will be described with reference to Modification 2.

[0035] 5 is a schematic diagram showing Modification 2, illustrating the configuration of the solid electrolyte layer 3. In this modification, a porous resin sheet (e.g., a foamed resin sheet) is used as the support 11. The pores in the support 11 are elliptical when viewed along the stacking direction. The elliptical pores extend along the tab direction. That is, the major axis direction (which can be said to be the extension direction) of the pores coincides with the tab direction.

[0036] In this modification, as in the previously described embodiment, the elongation rate in the tab direction is greater than that in the non-tab direction, so that even when a tensile force is applied to the solid electrolyte layer 3, the support 11 is less likely to deform, and the solid electrolyte is prevented from falling off.

[0037] That is, the support 11 does not necessarily have to contain long fibers, but may be a foamed resin sheet or the like as long as it has pores.

[0038] The material of the support 11 is not particularly limited. For example, insulating resins and ceramics can be used as the material of the support 11. Examples of resins used for the support 11 include PET, acrylic resin, nylon, and aramid. Examples of ceramics include glass and alumina.

[0039] There is no particular limitation on the thickness of the support 11. For example, the thickness of the support 11 is 100 μm or less, preferably 20 μm or less, and more preferably 1 to 20 μm.

[0040] (Number of stacked battery cells) In the above embodiment, a case where a plurality of battery cells 2 are stacked in the stacking direction as shown in Fig. 1 has been described. However, the configuration shown in Fig. 1 is merely an example, and it is not necessary to provide a plurality of battery cells 2. A single battery cell 2 may also be provided.

[0041] When a plurality of battery cells 2 are provided, it is preferable that the elongation rate of the support 11 in the tab direction is smaller than the elongation rate of the support in the non-tab direction in all of the plurality of battery cells 2. By adopting such a configuration, the solid electrolyte in all of the battery cells 2 is less likely to fall off.

[0042] (Others) Next, other configurations will be described.

[0043] The positive electrode layer 4 is a layer containing a positive electrode active material. The positive electrode layer 4 may be configured to absorb lithium during discharge and release lithium as lithium ions during charge. The positive electrode layer 4 is formed, for example, from a material containing a resin binder and a positive electrode active material dispersed in the resin binder. For example, a lithium metal composite oxide can be used as the positive electrode active material. The thickness of the positive electrode layer 4 is, for example, 30 to 1000 μm, preferably 10 to 500 μm.

[0044] The negative electrode layer 5 is a layer containing a negative electrode active material. The negative electrode layer 5 is configured to occlude lithium during charging and release lithium as lithium ions during discharging. For example, the negative electrode layer 5 can be formed from a material containing a resin binder and a negative electrode active material dispersed in the resin binder. Alternatively, the negative electrode layer 5 may be realized by metallic lithium that precipitates between the solid electrolyte layer 3 and the negative electrode current collector foil 7 during charging. That is, the all-solid-state battery 1 may be a so-called lithium deposition type secondary battery. In such a lithium deposition type secondary battery, there may be almost no metallic lithium as the negative electrode active material in a fully discharged state. However, at least the metallic lithium that precipitates during charging functions as the negative electrode layer 5, and therefore the all-solid-state battery 1 according to this embodiment is included.

[0045] The solid electrolyte layer 3 may include the support 11 and a solid electrolyte supported on the support 11. However, the solid electrolyte layer 3 may include components other than the support 11 and the solid electrolyte. For example, the solid electrolyte layer 3 may include a binder separate from the support 11, and the binder may bind the solid electrolyte particles together or the solid electrolyte particles to the support 11.

[0046] For example, an aluminum foil can be used as the positive electrode current collector foil 6. For example, a thin film of copper, a copper alloy, nickel, a nickel alloy, or the like can be used as the negative electrode current collector foil 7.

[0047] The method for manufacturing the all-solid-state battery 1 according to this embodiment is not particularly limited. For example, first, a support 11 is prepared. Then, a slurry containing a solid electrolyte, a polymer binder, and the like is prepared, and the prepared slurry is applied to the support 11 and dried. This results in a free-standing film for forming the solid electrolyte layer 3. Thereafter, the obtained free-standing film is combined with other components to obtain the all-solid-state battery 1.

[0048] Second Embodiment Next, a second embodiment will be described. In this embodiment, the configuration of the solid electrolyte layer 3 is changed from that of the first embodiment. Note that detailed description of the fact that the same configuration as that of the first embodiment can be adopted will be omitted.

[0049] 6 is a plan view schematically showing the configuration of the solid electrolyte layer 3 in this embodiment. In this embodiment, the solid electrolyte layer 3 includes a solid electrolyte and short fibers 21 dispersed in the solid electrolyte layer 3. That is, the short fibers 21 are used instead of the support 11 in the first embodiment. The short fibers 21 have the same function as the support 11 described in the first embodiment. That is, the inclusion of the short fibers 21 bonds the solid electrolyte particles together via the short fibers 21. As a result, the solid electrolyte layer 3 can be handled as a free-standing membrane.

[0050] Here, the short fibers 21 extend in a specific direction when viewed along the stacking direction. The extending direction of the short fibers 21 is referred to as the "extending direction," similar to the extending direction of the pores in the first embodiment. The extending direction is aligned with the tab direction.

[0051] The above is a schematic configuration of this embodiment. In this embodiment, as in the first embodiment, the solid electrolyte can be prevented from falling off. This point will be described with reference to a reference example.

[0052] 7A is a schematic diagram showing a reference example, illustrating the tab direction, non-tab direction, and the extending direction of the short fibers 21. In this reference example, the extending direction of the short fibers 21 coincides with the non-tab direction, not the tab direction.

[0053] As described above, the solid electrolyte layer 3 is likely to be subjected to a tensile force along the tab direction. That is, a tensile force is likely to be applied in a direction perpendicular to the extending direction of the short fibers 21. When a tensile force is applied in such a direction, stress is applied between the solid electrolyte particles 12, making the solid electrolyte more likely to fall off.

[0054] 7B is a schematic diagram showing the tab direction, non-tab direction, and extension direction of the short fibers 21 in this embodiment. In this embodiment, the extension direction coincides with the tab direction. In this embodiment, the direction in which tensile force is likely to be applied coincides with the extension direction of the short fibers 21. When tensile force is applied in such a direction, stress is likely to be applied to the short fibers 21 in the solid electrolyte layer 3, but is unlikely to be applied between the solid electrolyte particles 12. Therefore, the solid electrolyte particles 12 are unlikely to separate from each other, and falling off of the solid electrolyte can be prevented.

[0055] In this embodiment, as in the first embodiment, the elongation of the solid electrolyte layer 3 as a whole is small in the tab direction and large in the non-tab direction. In this respect, the present embodiment has a common configuration with the first embodiment, and as a result, it can be said that the solid electrolyte is prevented from falling off.

[0056] Also in this embodiment, similarly to the first embodiment, the solid electrolyte layer 3 may further contain a binder or the like in addition to the short fibers 21. The binder may bind the solid electrolyte particles together or the solid electrolyte particles and the short fibers 21 together.

[0057] The method for manufacturing the all-solid-state battery 1 according to this embodiment is not particularly limited. For example, a slurry containing the solid electrolyte particles 12 and the short fibers 21 is prepared, applied to a support material, and dried. After drying, the support material is removed. This makes it possible to obtain a free-standing film for forming the solid electrolyte layer 3. The free-standing film obtained is then combined with other components such as an electrode layer and a current collector foil to obtain the all-solid-state battery 1.

[0058] (Regarding the Extension Direction) In this embodiment, as in the first embodiment, the extension direction of the short fibers 21 does not necessarily have to completely coincide with the tab direction. The extension direction may deviate slightly from the tab direction. The angle formed between the extension direction of the short fibers 21 and the tab direction should be smaller than 45°, and is preferably within 10°.

[0059] Furthermore, when a plurality of short fibers 21 are present, the extending direction of the short fibers 21 can be identified by determining the average extending direction of the short fibers 21. Fig. 8 is a schematic diagram showing a third modification. In this modification, a plurality of short fibers 21 are included in the solid electrolyte layer 3. The extending direction of each short fiber 21 does not coincide with the tab direction. However, the average extending direction of the plurality of short fibers 21 coincides with the tab direction. If the average extending direction of the short fibers 21 is less than 45° with respect to the tab direction, a certain effect can be achieved in terms of preventing the solid electrolyte from falling off.

[0060] The average extension direction of the short fibers 21 can be determined by, for example, determining the extension direction of each of 50 short fibers 21 and calculating the number average. The extension direction of each short fiber 21 can be determined as the direction connecting both ends of each fiber 21. For example, each short fiber 21 is observed from the stacking direction using a microscope or the like, and a straight line connecting both ends of the fiber is drawn. The extension direction of this straight line can then be determined as the extension direction of each short fiber 21. If each short fiber 21 has branched portions, there may be multiple straight lines connecting both ends of the fiber. In such cases, the extension direction of the straight line that maximizes the distance between the ends is determined as the extension direction of each short fiber 21.

[0061] Furthermore, when a plurality of battery cells 2 are provided, it is preferable that the extension direction of the short fibers in all of the plurality of battery cells 2 be less than 45° with respect to the tab direction.

[0062] (Material of Short Fibers) The material of the short fibers 21 is not particularly limited. For example, insulating resins and ceramics can be used as the material of the short fibers 21. Examples of resins used for the short fibers 21 include PET, acrylic resin, nylon, and aramid. Examples of ceramics include glass and alumina.

[0063] Third Embodiment Next, a third embodiment will be described. Note that detailed description will be omitted for the points where the same configuration as in the previously described embodiments can be adopted.

[0064] 9 is a schematic cross-sectional view showing a portion of the all-solid-state battery 1 according to this embodiment. In this embodiment, the positional relationship between the outer circumferential edge of the solid electrolyte layer 3 and the outer circumferential edges of the positive electrode current collector foil 6 and the negative electrode current collector foil 7 is specified. In this embodiment, the outer circumferential edge of the solid electrolyte layer 3 is located outside the outer circumferential edge of at least one of the positive electrode current collector foil 6 and the negative electrode current collector foil 7.

[0065] Specifically, when viewed along the stacking direction, the outer shape of the battery cell 2 has multiple sides. When viewed along the stacking direction, on each of the multiple sides, the outer peripheral edge of the solid electrolyte layer 3 is located outward from the outer peripheral edge of at least one of the positive electrode current collector foil 6 and the negative electrode current collector foil 7. In the example shown in Fig. 9, on one side, the outer peripheral edge a-1 of the solid electrolyte layer 3 is located outward from the outer peripheral edge c-1 of the positive electrode current collector foil 6. On the opposite side, the outer peripheral edge a-2 of the solid electrolyte layer 3 is located outward from the outer peripheral edge b-2 of the negative electrode current collector foil 7.

[0066] According to this embodiment, contact between the positive electrode current collector foil 6 and the negative electrode current collector foil 7 is prevented by the solid electrolyte layer 3. Therefore, short circuits between the current collector foils can be prevented.

[0067] Fourth Embodiment Next, a fourth embodiment will be described. Note that detailed description will be omitted for the points where the same configuration as in the above-described embodiments can be adopted.

[0068] Fig. 10 is a plan view schematically illustrating the all-solid-state battery 1 according to this embodiment. As shown in Fig. 10, when viewed along the stacking direction, the outer peripheral edge of the solid electrolyte layer 3 is located outside the outer peripheral edges of the electrode layers (positive electrode layer 4 and negative electrode layer 5). As a result, when viewed along the stacking direction, the solid electrolyte layer 3 is provided with a frame-shaped non-electrode facing portion 14 that surrounds the electrode layers (positive electrode layer 4 and negative electrode layer 5). The non-electrode facing portion 14 is a region that does not overlap with either the positive electrode layer 4 or the negative electrode layer 5.

[0069] Here, the width of the non-electrode facing portion 14 at the end in the non-tab direction ("a" in FIG. 10) is smaller than the width of the non-electrode facing portion 14 at the end in the tab direction ("b" in FIG. 10).

[0070] According to this embodiment, since the width of the non-electrode facing portion 14 in the non-tab direction is small, the solid electrolyte layer 3 is less likely to stretch in the non-tab direction as well. Therefore, even if a tensile force is applied in the non-tab direction, the solid electrolyte is less likely to fall off. In other words, the solid electrolyte can be more reliably prevented from falling off.

[0071] Fifth Embodiment Next, a fifth embodiment will be described. Note that detailed description will be omitted for the fact that the same configuration as the previously described embodiments can be adopted.

[0072] 11 is a plan view schematically showing the all-solid-state battery 1 according to this embodiment. As in the fourth embodiment, in this embodiment, a frame-shaped non-electrode-facing portion 14 is provided on the solid electrolyte layer 3.

[0073] Here, the non-electrode facing portion 14 has a high-density region 16. The high-density region 16 is a region having a higher density than other portions of the solid electrolyte layer 3. The high-density region 16 is provided at an end of the non-electrode facing portion 14 in the non-tab direction.

[0074] In the high-density region 16, the solid electrolyte layer 3 is less likely to stretch. According to this embodiment, the high-density region 16 is provided at the end in the non-tab direction, so that the solid electrolyte is less likely to fall off even when a tensile force is applied in the non-tab direction. In other words, the solid electrolyte can be more reliably prevented from falling off.

[0075] When the solid electrolyte layer 3 includes the support 11 as in the first embodiment, the high-density region 16 may be a region where the density of the support 11 is higher than that of other portions. When the solid electrolyte layer 3 includes the short fibers 21 as in the second embodiment, the high-density region 16 may be a region where the density of the short fibers 21 is higher than that of other portions.

[0076] Sixth Embodiment Next, a sixth embodiment will be described. Note that detailed description will be omitted for the points where the same configuration as in the previously described embodiments can be adopted.

[0077] 12 is a plan view schematically illustrating the all-solid-state battery 1 according to this embodiment. Specifically, FIG. 12 illustrates the configuration of the solid electrolyte layer 3.

[0078] In this embodiment, similarly to the first embodiment, the solid electrolyte layer 3 has a support 11. Here, the support 11 has a solid electrolyte support region 17 that supports the solid electrolyte, and a non-support region 18 that is provided so as to surround the solid electrolyte support region 17. In the non-support region 18, the solid electrolyte is not supported by the support 11.

[0079] If the solid electrolyte is supported up to the edge of the support 11, the solid electrolyte is likely to fall off at the edge of the support 11. In contrast, according to this embodiment, the non-support region 18 is provided outside the solid electrolyte support region 17, so the solid electrolyte is less likely to fall off at the edge. In other words, the solid electrolyte can be more reliably prevented from falling off.

[0080] Seventh Embodiment Next, a seventh embodiment will be described. Note that detailed description will be omitted for the fact that the same configuration as the previously described embodiments can be adopted.

[0081] 13 is a plan view schematically showing an all-solid-state battery 1 according to this embodiment. In this embodiment, as in the first embodiment, the solid electrolyte layer 3 has a support 11. Also, as in the fourth and fifth embodiments, in this embodiment, a frame-shaped non-electrode-facing portion 14 is provided on the solid electrolyte layer 3.

[0082] Here, the non-electrode facing portion 14 is provided with a resin filled region 19 and a non-filled region 20. The resin filled region 19 is a region of the support body 11 filled with resin. The non-filled region 20 is a region not filled with resin. The resin filled region 19 is provided at the end of the non-electrode facing portion 14 in the non-tab direction.

[0083] Since the resin is filled in the resin-filled region 19, the solid electrolyte is less likely to fall off. According to this embodiment, the resin-filled region 19 is provided at the end in the non-tab direction, so the solid electrolyte is less likely to fall off even when a tensile force is applied in the non-tab direction. Therefore, the solid electrolyte is more reliably prevented from falling off.

[0084] The present invention has been described above using the first to seventh embodiments. Note that the above-described embodiments and modifications are not independent of each other and can be used in combination within a range that does not cause contradictions.

[0085] Representative configurations and effects of the present invention will be summarized below as appendices.

[0086] (Supplementary Note 1) An all-solid-state battery comprising: a battery cell (2) having a positive electrode layer (4), a solid electrolyte layer (3), and a negative electrode layer (5) stacked along a stacking direction; a positive electrode current collector foil (6) and a negative electrode current collector foil (7) arranged to sandwich the battery cell (2); and a positive electrode tab (9) and a negative electrode tab (10) connected to the positive electrode current collector foil (6) and the negative electrode current collector foil (7), respectively; a tab direction and a non-tab direction are defined as directions perpendicular to the stacking direction, where the tab direction is perpendicular to the non-tab direction; the positive electrode current collector foil (6) and the negative electrode current collector foil (7) are connected to the positive electrode tab (9) and the negative electrode tab (10), respectively, at their ends in the tab direction; the solid electrolyte layer (3) has a sheet-like support (11) and a solid electrolyte supported by the support (11); and the elongation rate of the support (11) in the tab direction is smaller than the elongation rate of the support (11) in the non-tab direction.

[0087] According to the above-mentioned configuration, the support is less likely to stretch in the tab direction where tensile force is likely to be applied, so the solid electrolyte is less likely to fall off.

[0088] (Supplementary Note 2) An all-solid-state battery comprising: a battery cell (2) having a positive electrode layer (4), a solid electrolyte layer (3), and a negative electrode layer (5) stacked along a stacking direction; a positive electrode current collector foil (6) and a negative electrode current collector foil (7) arranged to sandwich the battery cell (2); and a positive electrode tab (9) and a negative electrode tab (10) connected to the positive electrode current collector foil (6) and the negative electrode current collector foil (7), respectively; a tab direction and a non-tab direction are defined as directions perpendicular to the stacking direction, where the tab direction is perpendicular to the non-tab direction; the positive electrode current collector foil (6) and the negative electrode current collector foil (7) are connected to the positive electrode tab (9) and the negative electrode tab (10), respectively, at their ends in the tab direction; the solid electrolyte layer (3) has a solid electrolyte and fibers dispersed in the solid electrolyte layer; the fibers extend along an extension direction when viewed along the stacking direction; and an angle formed between the extension direction and the tab direction is smaller than 45°.

[0089] According to the above-described configuration, even if a tensile force is applied in the tab direction, the stress is generated mainly in the fibers, and is unlikely to be generated between the particles constituting the solid electrolyte, thereby preventing the solid electrolyte from falling off.

[0090] (Supplementary Note 3) The all-solid-state battery according to Supplementary Note 1, wherein the support 11 has pores 13 extending along the extension direction when viewed along the stacking direction, and an angle formed between the extension direction and the tab direction is smaller than 45°.

[0091] According to the above-described configuration, the elongation rate of the support in the tab direction tends to be smaller than the elongation rate of the support in the non-tab direction, which makes it difficult for the solid electrolyte to fall off.

[0092] (Supplementary Note 4) The all-solid-state battery according to any one of Supplementary Notes 1 to 3, wherein an angle formed between the extension direction and the tab direction is within 10°.

[0093] According to the above-described configuration, the support 11 is less likely to stretch in the tab direction, and the solid electrolyte is more reliably prevented from falling off.

[0094] (Appendix 5) The all-solid-state battery according to Appendix 1, wherein a plurality of battery cells 2 are provided, the plurality of battery cells 2 are stacked in the stacking direction via a positive electrode current collector foil 6 or a negative electrode current collector foil 7, and in all of the plurality of battery cells 2, the elongation rate of the support 11 in the tab direction is smaller than the elongation rate of the support 11 in the non-tab direction.

[0095] According to the above-described configuration, it is possible to prevent the solid electrolyte from falling off in all the battery cells.

[0096] (Appendix 6) The all-solid-state battery according to any one of Appendices 1 to 5, wherein, when viewed along the stacking direction, an outer peripheral edge of the solid electrolyte layer 3 is located outside an outer peripheral edge of at least one of the positive electrode current collector foil 6 and the negative electrode current collector foil 7.

[0097] According to the above-described configuration, contact between the positive electrode current collector foil and the negative electrode current collector foil can be prevented.

[0098] (Supplementary Note 7) The all-solid-state battery according to any one of Supplementary Notes 1 to 6, wherein, when viewed along the stacking direction, the outer peripheral edge of the solid electrolyte layer 3 is located outward from the outer peripheral edges of the positive electrode layer 4 and the negative electrode layer 5, and when viewed along the stacking direction, a region of the region where the solid electrolyte layer 3 is provided that does not overlap with either the positive electrode layer 4 or the negative electrode layer 5 is defined as a non-electrode facing portion 14, and the width of the non-electrode facing portion 14 at the end in the non-tab direction is smaller than the width of the non-electrode facing portion 14 at the end in the tab direction.

[0099] According to the above-described configuration, the solid electrolyte layer is less likely to stretch even at the end in the non-tab direction, and therefore the solid electrolyte is less likely to fall off even if a tensile force is applied in the non-tab direction.

[0100] (Appendix 8) The all-solid-state battery according to any one of Appendices 1 to 7, wherein, when viewed along the stacking direction, an outer peripheral edge of the solid electrolyte layer 3 is located outward from an outer peripheral edge of the positive electrode layer 4 and an outer peripheral edge of the negative electrode layer 5; when viewed along the stacking direction, a region of the region where the solid electrolyte layer 3 is provided that does not overlap with either the positive electrode layer 4 or the negative electrode layer 5 is defined as a non-electrode-facing portion 14; the solid electrolyte layer 3 has a high-density region 16 that is a region where its density is higher than other portions; and the high-density region 16 is provided at an end of the non-electrode-facing portion 14 in the non-tab direction.

[0101] According to the above-described configuration, the solid electrolyte layer is less likely to stretch at the end in the non-tab direction, and therefore the solid electrolyte is less likely to fall off even if a tensile force is applied in the non-tab direction.

[0102] (Supplementary Note 9) The all-solid-state battery according to Supplementary Note 1, wherein the support 11 has a solid electrolyte support region 17 that supports the solid electrolyte, and a non-support region 18 that is a region where no solid electrolyte is present and that is provided so as to surround the solid electrolyte support region 17 when viewed along the stacking direction.

[0103] According to the above-described configuration, the solid electrolyte is prevented from falling off at the end portions.

[0104] (Supplementary Note 10) The all-solid-state battery according to Supplementary Note 1, wherein, when viewed along the stacking direction, an outer peripheral edge of the solid electrolyte layer 3 is located outward from an outer peripheral edge of the positive electrode layer 4 and an outer peripheral edge of the negative electrode layer 5; when viewed along the stacking direction, a region of the region where the solid electrolyte layer 3 is provided that does not overlap with either the positive electrode layer 4 or the negative electrode layer 5 is defined as a non-electrode-facing portion 14; the non-electrode-facing portion 14 has a resin-filled region 19 that is a region filled with resin; and the resin-filled region 19 is provided at an end of the non-electrode-facing portion 14 in the non-tab direction.

[0105] According to the above-described configuration, the solid electrolyte layer is less likely to stretch at the end in the non-tab direction, and therefore the solid electrolyte is less likely to fall off even if a tensile force is applied in the non-tab direction.

[0106] (Supplementary Note 11) An all-solid-state battery comprising: a battery cell 2 having a positive electrode layer 4, a solid electrolyte layer 3, and a negative electrode layer 5 stacked along a stacking direction; a positive electrode current collector foil 6 and a negative electrode current collector foil 7 arranged to sandwich the battery cell 2; and a positive electrode tab 9 and a negative electrode tab 10 connected to the positive electrode current collector foil 6 and the negative electrode current collector foil 7, respectively; a tab direction and a non-tab direction are defined as directions perpendicular to the stacking direction, where the tab direction is perpendicular to the non-tab direction, and the positive electrode current collector foil 6 and the negative electrode current collector foil 7 are connected to the positive electrode tab 9 and the negative electrode tab 10 at their ends in the tab direction, respectively; and an elongation rate of the solid electrolyte layer 3 in the tab direction is smaller than the elongation rate of the solid electrolyte layer 3 in the non-tab direction.

[0107] According to the above-described configuration, the solid electrolyte layer is less likely to stretch in the tab direction where tensile force is likely to be applied, and therefore the solid electrolyte is less likely to fall off.

Claims

1. An all-solid-state battery comprising: a battery cell having a positive electrode layer, a solid electrolyte layer, and a negative electrode layer stacked along a stacking direction; a positive electrode current collector foil and a negative electrode current collector foil arranged to sandwich the battery cell; a positive electrode tab and a negative electrode tab connected to the positive electrode current collector foil and the negative electrode current collector foil, respectively; a tab direction and a non-tab direction are defined as directions perpendicular to the stacking direction, wherein the tab direction is perpendicular to the non-tab direction; the positive electrode current collector foil and the negative electrode current collector foil are connected to the positive electrode tab and the negative electrode tab, respectively, at their ends in the tab direction; the solid electrolyte layer has a sheet-like support and a solid electrolyte supported by the support, and an elongation rate of the support in the tab direction is smaller than an elongation rate of the support in the non-tab direction.

2. An all-solid-state battery comprising: a battery cell having a positive electrode layer, a solid electrolyte layer, and a negative electrode layer stacked along a stacking direction; a positive electrode current collector foil and a negative electrode current collector foil arranged to sandwich the battery cell; a positive electrode tab and a negative electrode tab connected to the positive electrode current collector foil and the negative electrode current collector foil, respectively; a tab direction and a non-tab direction are defined as directions perpendicular to the stacking direction, wherein the tab direction is perpendicular to the non-tab direction; the positive electrode current collector foil and the negative electrode current collector foil are connected to the positive electrode tab and the negative electrode tab, respectively, at their ends in the tab direction; the solid electrolyte layer has a solid electrolyte and fibers dispersed therein, the fibers extend along an extension direction when viewed along the stacking direction, and an angle formed between the extension direction and the tab direction is less than 45°.

3. An all-solid-state battery as claimed in claim 1, wherein the support has pores extending along an extension direction when viewed along the stacking direction, and an angle formed between the extension direction and the tab direction is smaller than 45°.

4. An all-solid-state battery according to claim 3, wherein an angle formed between the extension direction and the tab direction is within 10°.

5. An all-solid-state battery as claimed in claim 1, wherein a plurality of the battery cells are provided, the plurality of battery cells are stacked in the stacking direction via the positive electrode current collector foil or the negative electrode current collector foil, and in all of the plurality of battery cells, the elongation rate of the support in the tab direction is smaller than the elongation rate of the support in the non-tab direction.

6. An all-solid-state battery as claimed in claim 1, wherein, when viewed along the stacking direction, the outer peripheral edge of the solid electrolyte layer is positioned outside the outer peripheral edges of at least one of the positive electrode current collector foil and the negative electrode current collector foil.

7. An all-solid-state battery as claimed in claim 1, wherein, when viewed along the stacking direction, an outer peripheral edge of the solid electrolyte layer is located outside the outer peripheral edges of the positive electrode layer and the negative electrode layer, when viewed along the stacking direction, a region of the region in which the solid electrolyte layer is provided that does not overlap with either the positive electrode layer or the negative electrode layer is defined as a non-electrode facing portion, and the width of the non-electrode facing portion at the end in the non-tab direction is smaller than the width of the non-electrode facing portion at the end in the tab direction.

8. An all-solid-state battery as defined in claim 1, wherein, when viewed along the stacking direction, an outer peripheral edge of the solid electrolyte layer is located outside the outer peripheral edges of the positive electrode layer and the negative electrode layer, and when viewed along the stacking direction, a region of the region in which the solid electrolyte layer is provided that does not overlap with either the positive electrode layer or the negative electrode layer is defined as a non-electrode facing portion, and the solid electrolyte layer has a high-density region which is a region in which the density is higher than other portions, and the high-density region is provided at an end of the non-electrode facing portion in the non-tab direction.

9. An all-solid-state battery as claimed in claim 1, wherein the support has a solid electrolyte support region that supports the solid electrolyte, and a non-support region that is a region in which the solid electrolyte is not present and is arranged to surround the solid electrolyte support region when viewed along the stacking direction.

10. An all-solid-state battery as claimed in claim 1, wherein, when viewed along the stacking direction, an outer peripheral edge of the solid electrolyte layer is located outside the outer peripheral edges of the positive electrode layer and the negative electrode layer, and when viewed along the stacking direction, a region of the region in which the solid electrolyte layer is provided that does not overlap with either the positive electrode layer or the negative electrode layer is defined as a non-electrode facing portion, and the non-electrode facing portion has a resin-filled region that is a region filled with resin, and the resin-filled region is provided at an end of the non-electrode facing portion in the non-tab direction.

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