All-solid-state battery

Abstract

This all-solid-state battery comprises a solid electrolyte layer, a positive electrode layer, and a negative electrode layer. The solid electrolyte layer includes a solid electrolyte and first fibers having a melting point of 100-200° C. The first fibers have insulating properties at least in the range of 200°C or less. At least some of the first fibers exist near a surface of the solid electrolyte layer such that protrusions corresponding to the first fibers are formed on the surface of the solid electrolyte layer.

Description

All solid state battery

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

[0002] All-solid-state batteries are secondary batteries in which all components, including the electrolyte layer, are substantially solid. In all-solid-state batteries, lithium ions are typically transferred between the positive and negative electrode layers to charge and discharge the battery.

[0003] In the event that an all-solid-state battery generates abnormal heat, it is desirable that the battery stop operating, i.e., it is desirable that the battery have a shutdown function.

[0004] It is known that a porous separator is used in a lithium-ion battery using a liquid electrolyte to obtain a shutdown function (for example, Non-Patent Document 1 (Akira Yoshino, Technical Trends of Separators for Lithium-Ion Batteries, Functional Paper Research Association Paper No. 54, pp. 9-13, October 2015)).

[0005] However, all-solid-state batteries generally do not have a shutdown function. Therefore, an object of the present invention is to provide an all-solid-state battery that has a shutdown function.

[0006] In one aspect, an all-solid-state battery according to the present invention includes a solid electrolyte layer, and a positive electrode layer and a negative electrode layer disposed so as to sandwich the solid electrolyte layer in a thickness direction. The solid electrolyte layer includes a solid electrolyte and first fibers having a melting point of 100 to 200°C. The first fibers are insulating at least in the range of 200°C or lower. At least some of the first fibers are present near the surface of the solid electrolyte layer so that protrusions corresponding to the first fibers are formed on the surface of the solid electrolyte layer.

[0007] FIG. 1 is a schematic cross-sectional view showing a main portion of an all-solid-state battery according to a first embodiment. FIG. 2 is a schematic cross-sectional view for explaining a shutdown function. FIG. 3 is a schematic cross-sectional view showing a main portion of an all-solid-state battery according to a second embodiment. FIG. 4 is a schematic cross-sectional view showing a main portion of an all-solid-state battery according to a third embodiment. FIG. 5 is a schematic cross-sectional view showing a main portion of an all-solid-state battery according to a fourth embodiment. FIG. 6 is a schematic cross-sectional view showing a main portion of an all-solid-state battery according to a fifth embodiment. FIG. 7 is a schematic cross-sectional view showing a main portion of an all-solid-state battery according to a sixth embodiment. FIG. 8 is a schematic cross-sectional view showing a main portion of an all-solid-state battery according to a seventh embodiment. FIG. 9 is a schematic cross-sectional view showing a main portion of an all-solid-state battery according to an eighth embodiment.

[0008] Hereinafter, an all-solid-state battery according to an embodiment of the present invention will be described with reference to the drawings.

[0009] 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.

[0010] First Embodiment Fig. 1 is a schematic cross-sectional view showing the main parts of an all-solid-state battery 1 according to this embodiment. As shown in Fig. 1, this all-solid-state battery 1 has a solid electrolyte layer 2, a positive electrode layer 3, and a negative electrode layer 4. The positive electrode layer 3 and the negative electrode layer 4 are arranged to sandwich the solid electrolyte layer 2 in the thickness direction. Although not shown, a negative electrode current collector foil is arranged on the outer surface of the negative electrode layer 4, and a positive electrode current collector foil is arranged on the outer surface of the positive electrode layer 3.

[0011] The positive electrode layer 3 is a layer containing a positive electrode active material. The positive electrode layer 3 is configured to release lithium during charging and to absorb lithium during discharging. For example, the positive electrode layer 3 is formed from a material containing a resin binder and a positive electrode active material dispersed in the resin binder. The positive electrode active material is not particularly limited, but an NMC-based positive electrode active material, for example, can be used. The thickness of the positive electrode layer 3 is, for example, 10 to 1000 μm, preferably 30 to 500 μm.

[0012] The negative electrode layer 4 is a layer containing a negative electrode active material. The negative electrode layer 4 is configured to absorb lithium during charging and release lithium during discharging. Alternatively, the negative electrode layer 4 may be composed of metallic lithium that precipitates between the solid electrolyte layer 2 and the negative electrode current collector foil during charging. That is, the all-solid-state battery 1 may be a "precipitation-type all-solid-state battery." In such a precipitation-type all-solid-state battery, there may be almost no metallic lithium present as a negative electrode active material in a fully discharged state. However, at least metallic lithium that precipitates as a negative electrode active material during discharging functions as the negative electrode layer 4. Therefore, a precipitation-type all-solid-state battery is also included in the all-solid-state battery of this embodiment.

[0013] The solid electrolyte layer 2 is a layer through which lithium ions are conducted during charging and discharging. The solid electrolyte layer 2 includes a solid electrolyte and first fibers 5.

[0014] The solid electrolyte is a substance that has electronic insulating properties and ionic conductivity. The solid electrolyte is not particularly limited, but for example, a sulfide solid electrolyte can be used.

[0015] The first fibers 5 are contained in the solid electrolyte layer 2 as a filler. That is, the first fibers 5 are short fibers and dispersed in the solid electrolyte layer 2. The inclusion of the first fibers 5 prevents cracks from occurring in the solid electrolyte layer 2. Furthermore, the inclusion of the first fibers 5 can also impart self-supporting properties to the solid electrolyte layer 2.

[0016] 1 is a cross-sectional view, the first fibers 5 are depicted as being generally circular or elliptical. That is, depending on the direction in which the first fibers 5 extend, the first fibers 5 may have an elliptical shape in the cross-sectional view, as shown in FIG.

[0017] The first fibers 5 are also used to impart a shutdown function to the solid electrolyte layer 2. The first fibers 5 have a melting point of 100 to 200°C. The first fibers 5 are insulating at least in the range of 200°C or lower. More specifically, the first fibers 5 are electronically and ionically insulating at least in the range of 200°C or lower.

[0018] At least some of the first fibers 5 are present near the surface of the solid electrolyte layer 2. As a result, convex portions corresponding to the first fibers 5 are formed on the surface of the solid electrolyte layer 2. That is, at least some of the first fibers 5 are present near the surface of the solid electrolyte layer 2 to such an extent that convex portions are formed on the surface of the solid electrolyte layer 2. In other words, convex portions are formed on the surface of the solid electrolyte layer 2. At least some of the first fibers 5 are present inside the convex portions. Note that this configuration can be confirmed, for example, by observing an SEM image of the solid electrolyte layer 2.

[0019] The above-described configuration realizes a shutdown function, which will be described with reference to Fig. 2. Fig. 2 is a schematic cross-sectional view illustrating the shutdown function in this embodiment.

[0020] 2(a) is a schematic cross-sectional view showing the configuration during normal operation (charging). During normal operation, ions (lithium ions) are conducted between the positive electrode layer 3 and the negative electrode layer 4 via the solid electrolyte layer 2. In this case, the first fibers 5 do not particularly hinder ion conduction.

[0021] On the other hand, FIG. 2( b ) is a schematic cross-sectional view showing the configuration during abnormal heat generation. During abnormal heat generation, the first fibers 5 melt. Here, the first fibers 5 present in the convex portions on the surface of the solid electrolyte layer 2 are present near the interface between the solid electrolyte layer 2 and the electrode layers (positive electrode layer and negative electrode layer). At the interface, the molten material is more likely to spread in the planar direction than inside the layer. Therefore, when the first fibers 5 present in the convex portions melt, they are particularly likely to spread in the planar direction. The melted first fibers 5 spread and eliminate the ion conduction path between the positive electrode layer 3 and the negative electrode layer 4. This reduces or stops the battery's function. In other words, the all-solid-state battery 1 shuts down.

[0022] The above is an outline of this embodiment.

[0023] In the all-solid-state battery 1, oxygen usually begins to be released from the positive electrode layer 3 when the temperature exceeds 200°C (e.g., 220°C). It is desirable to avoid oxygen release from the positive electrode layer 3. According to the present embodiment, since the first fibers 5 have a melting point of 200°C or less, the all-solid-state battery 1 can be shut down before the positive electrode layer 3 reaches the oxygen release temperature.

[0024] Furthermore, a portion of the first fibers 5 may protrude from the surface of the solid electrolyte layer 2 into the electrode layers (the positive electrode layer 3 and the negative electrode layer 4). That is, the tips of the first fibers 5 may be present within the electrode layers. However, preferably, the surfaces of the first fibers 5 are covered with the solid electrolyte. That is, the first fibers 5 do not protrude from the surface of the solid electrolyte layer 2 toward the electrode layers. By adopting such a configuration, it is possible to suppress variations in ion conduction due to the presence of the first fibers 5 during normal operation. That is, it is possible to prevent a deterioration in battery characteristics during normal operation.

[0025] The height of the protrusions on the surface of the solid electrolyte layer 2 formed by the first fibers 5 is, for example, 1 μm or more, preferably 3 to 100 μm, and more preferably 5 to 30 μm. The height of the protrusions can be determined, for example, by observing an SEM image.

[0026] The fiber length of the first fibers 5 is appropriately set in consideration of self-supporting ability, dispersibility, and the like. The fiber length of the first fibers 5 is preferably 10 to 50,000 μm, more preferably 50 to 10,000 μm, and even more preferably 100 to 1,000 μm. If the fiber length is 10 μm or more, self-supporting ability is easily imparted to the solid electrolyte layer 2. On the other hand, if the fiber length is 50,000 μm or less, the dispersibility of the first fibers 5 in the solid electrolyte layer 2 is improved, and a uniform solid electrolyte layer 2 is easily obtained.

[0027] Preferably, cut fibers, all of which are aligned to approximately the same length, are used as the first fibers 5. However, the fiber lengths of the first fibers 5 may vary. In this case, the fiber length of the first fibers 5 refers to the number-average fiber length.

[0028] The thickness of the first fibers 5 (fiber diameter, or number average fiber diameter if there is variation) is appropriately set from the viewpoints of current density distribution and shutdown function. Specifically, the fiber diameter of the first fibers 5 is preferably 1 to 50 μm, more preferably 1 to 30 μm, and even more preferably 1 to 10 μm. If the fiber diameter is 1 μm or more, ionic conductivity is likely to decrease in the event of abnormal heat generation. In other words, the shutdown function is likely to be realized. On the other hand, if the fiber diameter is 50 μm or less, deterioration of the current density distribution during normal operation can be prevented.

[0029] In order to obtain a good shutdown function, the fiber diameter of the first fibers 5 is preferably larger than the particle diameter (number average particle diameter) of the solid electrolyte.

[0030] The content of the first fibers 5 is determined in consideration of the shutdown function and ionic conductivity during normal operation. Specifically, the volume fraction of the first fibers 5 in the solid electrolyte layer 2 is preferably 1 to 30%, more preferably 2 to 25%, and even more preferably 5 to 20%. If the volume fraction of the first fibers 5 is 1% or more, the shutdown function is easily obtained. If the volume fraction of the first fibers 5 is 30% or less, sufficient ionic conductivity during normal operation is ensured.

[0031] The volume fraction of the first fibers 5 can be calculated using a focused ion beam-scanning electron microscope (FIB-SEM). Specifically, the cross section of the solid electrolyte layer 2 is smoothed with an ion beam, and the cross section is observed with an SEM to identify the first fibers 5. The cross section is then sliced ​​with an ion beam, and the first fibers 5 are then identified. This process is repeated, and the three-dimensional structure of the first fibers 5 is determined from the results of identifying the first fibers 5 in multiple cross sections. This makes it possible to calculate the volume fraction.

[0032] The material of the first fibers 5 is not particularly limited, but examples thereof include polyolefins (such as polyethylene and polypropylene), polyesters, and the like.

[0033] The solid electrolyte layer 2 may contain components other than the solid electrolyte and the first fibers 5. For example, the solid electrolyte layer 2 may have a binder in addition to the first fibers 5, and the binder may bind the solid electrolyte particles together or the solid electrolyte particles to the first fibers 5.

[0034] The method for manufacturing the all-solid-state battery 1 according to this embodiment is not particularly limited. For example, first, a slurry containing a solid electrolyte and the first fibers 5 is prepared. The prepared slurry is then applied to a support film and dried. Next, the support film is removed. This results in a free-standing film. In the obtained free-standing film, convex portions corresponding to the first fibers are formed on the surface opposite to the surface on which the support film was provided. The surface on which the support film was provided becomes smooth. Next, two free-standing films obtained are bonded together. At this time, the two free-standing films are bonded together so that the surfaces on which the convex portions are provided face opposite sides. This results in a free-standing film having convex portions formed by the first fibers on both sides. Furthermore, the obtained free-standing film is laminated with a positive electrode layer, a negative electrode layer, and the like to obtain the all-solid-state battery 1.

[0035] Second Embodiment Next, a second embodiment will be described. Note that detailed description of the second embodiment will be omitted for the fact that the same configuration as the first embodiment can be adopted.

[0036] 3 is a schematic cross-sectional view showing a main part of the all-solid-state battery according to this embodiment. In this embodiment, the configuration of the solid electrolyte layer 2 is improved. In this embodiment, the volume fraction of the first fibers 5 in the solid electrolyte layer 2 varies in the thickness direction. Specifically, in the solid electrolyte layer 2, the volume fraction of the first fibers 5 in the region on the positive electrode layer 3 side is larger than that in the region on the negative electrode layer 4 side.

[0037] According to this embodiment, the ionic conductivity can be more reliably reduced during abnormal heat generation. The rate-limiting factor in the charge / discharge reaction is the interfacial resistance between the solid electrolyte layer 2 and the positive electrode layer 3. Therefore, a high volume fraction of the first fibers 5 in the region on the positive electrode layer side tends to hinder ionic conduction during abnormal heat generation.

[0038] The volume fraction of the first fibers 5 can be controlled, for example, by the number of the first fibers 5. For example, during production, two solid electrolyte sheets having different numbers of the first fibers 5 are prepared and then laminated together. This makes it possible to obtain a solid electrolyte layer 2 having different volume fractions of the first fibers 5 in the thickness direction.

[0039] On the other hand, the volume fraction of the first fibers 5 may be controlled in other ways. For example, by changing the size (thickness or length) of the first fibers 5, it is possible to realize a solid electrolyte layer 2 having different volume fractions in the thickness direction.

[0040] 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.

[0041] 4 is a schematic cross-sectional view showing a main part of the all-solid-state battery according to this embodiment. In this embodiment, as in the second embodiment, the volume fraction of the first fibers 5 in the solid electrolyte layer 2 varies in the thickness direction.

[0042] Specifically, the solid electrolyte layer 2 has a central region and a pair of outer regions. The central region is located at the center in the thickness direction. The pair of outer regions are provided to sandwich a middle region in the thickness direction. Here, the volume fraction of the first fibers 5 in the pair of outer regions is greater than the volume fraction of the first fibers 5 in the central region.

[0043] According to this embodiment, the ionic conductivity can be more reliably reduced during abnormal heat generation. The rate-limiting factor in the charge / discharge reaction is the interfacial resistance between the solid electrolyte layer 2 and each electrode layer (the positive electrode layer 3 and the negative electrode layer 4). Therefore, by increasing the volume fraction of the first fibers 5 in the outer region, ionic conduction during abnormal heat generation is more likely to be hindered.

[0044] The solid electrolyte layer 2 in this embodiment can be obtained, for example, by laminating a twice-coated sheet and a once-coated sheet. Specifically, first, a solid electrolyte slurry containing a small amount of first fibers 5 is applied to a support film to form a layer intended to become the central region. Furthermore, a solid electrolyte slurry containing a large amount of first fibers 5 is applied to the above layer to form a layer intended to become the outer region. This results in a twice-coated sheet. Meanwhile, a solid electrolyte slurry containing a large amount of first fibers 5 is applied to a support film to form a layer intended to become the outer region. This results in a once-coated sheet. Next, the support film is peeled off as necessary. The twice-coated sheet and the once-coated sheet are then laminated together. This results in the solid electrolyte layer 2 according to this embodiment.

[0045] (Fourth embodiment) Next, a fourth embodiment will be described. This embodiment can be said to be a modified example of the third embodiment. Detailed description of the features that can employ the same configuration as the third embodiment will be omitted.

[0046] 5 is a schematic cross-sectional view showing a main part of the all-solid-state battery according to this embodiment. In this embodiment, as in the third embodiment, the solid electrolyte layer 2 has a central region and a pair of outer regions. The volume fraction of the first fibers 5 in the pair of outer regions is greater than that in the central region.

[0047] In this embodiment, the volume fraction of the first fibers 5 in the outer region on the positive electrode layer 3 side is greater than the volume fraction of the first fibers 5 in the outer region on the negative electrode layer 4 side.

[0048] As described above, the interfacial resistance between the solid electrolyte layer 2 and each electrode layer is likely to be the rate-limiting factor for charge / discharge reactions. Here, the interfacial resistance between the solid electrolyte layer 2 and the positive electrode layer 3 is more likely to be the rate-limiting factor than the interfacial resistance between the solid electrolyte layer 2 and the negative electrode layer 4. Therefore, by increasing the volume fraction of the first fibers 5 in the outer region on the positive electrode layer 3 side, ion conduction during abnormal heat generation can be more reliably prevented.

[0049] In this embodiment, similarly to the third embodiment, the solid electrolyte layer 2 can be obtained by laminating a twice-coated sheet and a once-coated sheet together.

[0050] Fifth Embodiment Next, a fifth embodiment will be described. Detailed description will be omitted for the points where the same configuration as the above-described embodiments can be adopted.

[0051] FIG. 6 is a schematic cross-sectional view showing the main parts of the all-solid-state battery according to this embodiment.

[0052] In this embodiment, the anode layer 4 contains metallic lithium as the anode active material. That is, the anode layer 4 is realized by metallic lithium that is deposited on the solid electrolyte layer 2 during charging. In other words, the all-solid-state battery 1 according to this embodiment is a deposition-type all-solid-state battery.

[0053] Here, protrusions corresponding to the first fibers 5 are formed on the surface of the solid electrolyte layer 2 facing the positive electrode layer 3. On the other hand, no protrusions are provided on the surface of the solid electrolyte layer 2 facing the negative electrode layer 4. In other words, the surface of the solid electrolyte layer 2 facing the negative electrode layer 4 is smooth.

[0054] In a precipitation-type all-solid-state battery such as that of this embodiment, if there are irregularities on the surface of the solid electrolyte layer 2 facing the negative electrode, the deposited metallic lithium is likely to vary. In contrast, according to this embodiment, the surface of the solid electrolyte layer 2 facing the negative electrode layer 4 is smooth, so that the variation in the deposition of metallic lithium is reduced. In other words, the shutdown function can be realized without interfering with the uniform deposition of metallic lithium during normal operation.

[0055] Sixth Embodiment Next, a sixth embodiment will be described. Detailed description will be omitted for the points where the same configuration as the above-described embodiments can be adopted.

[0056] 7 is a schematic cross-sectional view showing a main part of the all-solid-state battery according to this embodiment. In this embodiment, the solid electrolyte layer 2 further includes second fibers 6.

[0057] The second fibers 6 are used to maintain the self-supporting property of the solid electrolyte layer 2 even during abnormal heat generation. The second fibers 6 are arranged in the center of the solid electrolyte layer 2 in the thickness direction. The second fibers 6 are arranged in a position sandwiched between the first fibers 5 in the thickness direction.

[0058] The second fibers 6 have a melting point of 200° C. or higher. The second fibers 6 also have the function of imparting self-supporting properties to the solid electrolyte layer 2.

[0059] According to this embodiment, the second fibers 6 having a melting point of 200° C. or higher are provided, so that the solid electrolyte layer 2 can maintain its self-supporting property even during abnormal heat generation.

[0060] Preferably, the second fibers 6 have ion conductivity. If the second fibers 6 have ion conductivity, it is possible to suppress a decrease in ion conductivity during normal operation.

[0061] As the second fibers 6, for example, short fibers can be used.

[0062] The fiber length of the second fibers 6 (number average fiber length if there is variation) is appropriately set from the viewpoints of self-supporting ability and dispersibility. The fiber length of the second fibers 6 is preferably 10 to 50,000 μm, more preferably 50 to 10,000 μm, and even more preferably 100 to 1,000 μm. If the fiber length is 10 μm or more, self-supporting ability is easily imparted to the solid electrolyte layer 2. If the fiber length is 50,000 μm or less, good dispersibility is obtained, and a uniform solid electrolyte layer 2 is easily obtained.

[0063] The thickness of the second fibers 6 (fiber diameter, or number average fiber diameter if there is variation) is appropriately set in consideration of the self-supporting property and current density distribution. The fiber diameter is preferably 0.001 to 50 μm, more preferably 0.01 to 30 μm, and even more preferably 0.1 to 10 μm. If the fiber diameter is 0.001 μm or more, sufficient dispersibility can be obtained, and a uniform solid electrolyte layer 2 can be obtained. If the fiber diameter is 50 μm or less, variation in current density distribution can be sufficiently suppressed.

[0064] Seventh Embodiment Next, a seventh embodiment will be described. Detailed description will be omitted for the points where the same configuration as in the above-described embodiments can be adopted.

[0065] 8 is a schematic cross-sectional view showing the main part of the all-solid-state battery according to this embodiment. In this embodiment, the configuration of the solid electrolyte layer 2 is improved.

[0066] 8 , the solid electrolyte layer 2 has a central portion 7 and an outer peripheral portion 8. The central portion 7 is the center portion in the planar direction. The outer peripheral portion 8 is the outer peripheral portion in the planar direction. In other words, when viewed along the thickness direction, the outer peripheral portion 8 is provided at a position surrounding the central portion 7.

[0067] Here, the volume fraction of the first fibers 5 in the outer periphery 8 is greater than that in the central portion 7 .

[0068] According to this embodiment, it is possible to prevent cracks from occurring at the ends of the solid electrolyte layer 2. In all-solid-state batteries, cracks may occur at the ends of the solid electrolyte layer 2 due to pressure being applied to the laminate during manufacturing, expansion and contraction of the electrode layers during charge and discharge, etc. In contrast, according to this embodiment, the volume fraction of the first fibers 5 is increased at the ends (outer periphery) of the solid electrolyte layer 2, so that cracks are less likely to occur at the ends of the solid electrolyte layer 2.

[0069] Eighth Embodiment Next, an eighth embodiment will be described. Detailed description will be omitted for the points where the same configuration as in the above-described embodiments can be adopted.

[0070] 9 is a schematic cross-sectional view showing a main portion of the all-solid-state battery according to this embodiment. As shown in FIG. 9, in this embodiment, when viewed along the thickness direction (i.e., in the planar direction), the outer peripheral edge of the negative electrode layer 4 is located outside the outer peripheral edge of the positive electrode layer 3. By adopting such a configuration, it is possible to prevent the formation of lithium dendrites.

[0071] Here, the distance between the outer peripheral edge of the negative electrode layer 4 and the outer peripheral edge of the positive electrode layer 3 when viewed along the thickness direction is defined as distance a. The fiber length (number average fiber length) of the first fibers 5 is greater than distance a. In Fig. 9 , the length of each first fiber 5 is depicted as being smaller than distance a. However, this is because Fig. 9 is a cross-sectional view, and the fiber length of the first fibers 5 is actually greater than distance a.

[0072] According to this embodiment, the fiber length of the first fibers 5 is greater than the distance a, so that cracks are less likely to occur at the end of the solid electrolyte layer 2 .

[0073] The present invention has been described above with reference to the first to eighth embodiments. Note that the above-described embodiments are not independent of one another and can be combined within a range that does not cause contradictions.

[0074] Below, the typical configurations of the present invention and their effects will be summarized as appendices.

[0075] (Supplementary Note 1) An all-solid-state battery comprising a solid electrolyte layer 2, and a positive electrode layer 3 and a negative electrode layer 4 arranged to sandwich the solid electrolyte layer 2 in a thickness direction, wherein the solid electrolyte layer 2 includes a solid electrolyte and first fibers 5 having a melting point of 100 to 200°C, the first fibers 5 having insulating properties at least in a range of 200°C or lower, and at least some of the first fibers 5 being present in the vicinity of a surface of the solid electrolyte layer 2 so as to form convex portions corresponding to the first fibers 5 on the surface of the solid electrolyte layer 2.

[0076] With this configuration, the first fibers 5 melt and spread in the planar direction when abnormal heat is generated, resulting in the disappearance of ion conduction paths and the shutting down of the all-solid-state battery.

[0077] (Supplementary Note 2) The all-solid-state battery according to Supplementary Note 1, wherein in the solid electrolyte layer 2, a volume fraction of the first fibers on the positive electrode layer 3 side is greater than a volume fraction of the first fibers on the negative electrode layer side.

[0078] With this configuration, the all-solid-state battery can be shut down more reliably in the event of abnormal heat generation.

[0079] (Supplementary Note 3) The all-solid-state battery according to Supplementary Note 1 or 2, wherein the solid electrolyte layer 2 has a central region located at a center in a thickness direction and a pair of outer regions provided so as to sandwich the central region in the thickness direction, and a volume fraction of the first fibers in the pair of outer regions is larger than a volume fraction of the first fibers in the central region.

[0080] With this configuration, the all-solid-state battery can be shut down more reliably in the event of abnormal heat generation.

[0081] (Supplementary Note 4) The all-solid-state battery according to Supplementary Note 3, wherein, in the pair of outer regions, a volume fraction of the first fibers in the outer region on the positive electrode layer side is greater than a volume fraction of the first fibers in the outer region on the negative electrode layer side.

[0082] With this configuration, the all-solid-state battery can be shut down more reliably in the event of abnormal heat generation.

[0083] (Appendix 5) The all-solid-state battery according to any one of Appendices 1 to 4, wherein the anode layer 4 contains metallic lithium as an anode active material, and the convex portion is formed only on a surface of the solid electrolyte layer 2 that faces the cathode layer 3, and is not formed on a surface of the solid electrolyte layer 2 that faces the anode layer 4.

[0084] According to this configuration, the all-solid-state battery can be shut down in the event of abnormal heat generation without interfering with the deposition of metallic lithium during charging.

[0085] (Supplementary Note 6) The all-solid-state battery according to any one of Supplementary Notes 1 to 5, wherein the solid electrolyte layer 2 further includes second fibers 6 having a melting point of 200° C. or higher.

[0086] With this configuration, the presence of the second fibers 6 allows the solid electrolyte layer 2 to maintain its self-supporting properties even during abnormal heat generation.

[0087] (Supplementary Note 7) The all-solid-state battery according to Supplementary Note 6, wherein the second fibers 6 have ion conductivity.

[0088] With this configuration, the ionic conductivity of the solid electrolyte layer 2 can be ensured during normal operation.

[0089] (Supplementary Note 8) The all-solid-state battery according to any one of Supplementary Notes 1 to 7, wherein the solid electrolyte layer has a central portion 7 located in the center when viewed along the thickness direction, and an outer peripheral portion 8 arranged so as to surround the central portion 7 in the thickness direction, and the volume fraction of the first fibers in the outer peripheral portion 8 is greater than the volume fraction of the first fibers in the central portion 7.

[0090] With this configuration, it is possible to prevent cracks from occurring at the ends of the solid electrolyte layer 2 .

[0091] (Supplementary Note 9) The all-solid-state battery according to any one of Supplementary Notes 1 to 8, wherein, when viewed in the thickness direction, an outer peripheral edge of the anode layer 4 is located outward from an outer peripheral edge of the cathode layer 3, a distance between the outer peripheral edge of the anode layer 4 and the outer peripheral edge of the cathode layer 3 when viewed in the thickness direction is defined as a distance a, and a fiber length of the first fibers is longer than the distance a.

[0092] With this configuration, it is possible to prevent cracks from occurring at the ends of the solid electrolyte layer 2 .

Claims

1. An all-solid-state battery comprising: a solid electrolyte layer; and a positive electrode layer and a negative electrode layer arranged so as to sandwich the solid electrolyte layer in a thickness direction, wherein the solid electrolyte layer includes a solid electrolyte and first fibers having a melting point of 100 to 200°C, the first fibers having insulating properties at least in a range of 200°C or lower, and at least a portion of the first fibers being present in the vicinity of a surface of the solid electrolyte layer so as to form convex portions corresponding to the first fibers on the surface of the solid electrolyte layer.

2. An all-solid-state battery as claimed in claim 1, wherein in the solid electrolyte layer, the volume fraction of the first fibers on the positive electrode layer side is greater than the volume fraction of the first fibers on the negative electrode layer side.

3. An all-solid-state battery as claimed in claim 1 or 2, wherein the solid electrolyte layer has a central region located in the center in the thickness direction, and a pair of outer regions arranged to sandwich the central region in the thickness direction, and the volume fraction of the first fibers in the pair of outer regions is greater than the volume fraction of the first fibers in the central region.

4. An all-solid-state battery as described in claim 3, wherein in the pair of outer regions, the volume fraction of the first fibers in the outer region on the positive electrode layer side is greater than the volume fraction of the first fibers in the outer region on the negative electrode layer side.

5. An all-solid-state battery as claimed in claim 1 or 2, wherein the anode layer contains metallic lithium as an anode active material, and the protrusions are formed only on the surface of the solid electrolyte layer facing the cathode layer, and are not formed on the surface facing the anode layer.

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