All-solid-state battery

Abstract

The present application provides a kind of full solid-state battery for inhibiting crack in the side of solid electrolyte layer, and inhibiting the lithium precipitation of the side of solid electrolyte layer. Full solid-state battery has positive electrode layer, solid electrolyte layer and negative electrode layer, wherein, solid electrolyte layer at least in the end of the direction orthogonal to the stacking direction of positive electrode layer, solid electrolyte layer and negative electrode layer includes solid electrolyte particle with particle size of 1 μm or less, the density of solid electrolyte layer at least in the end of the direction orthogonal to the stacking direction is 1.90 g / cm 3 The above.

Description

Technical Field

[0001] This application claims priority based on Japanese Patent Application No. 2025-049372, filed on March 25, 2025, the contents of which are incorporated herein by reference.

[0002] This invention relates to all-solid-state batteries. Background Technology

[0003] All-solid-state lithium-ion secondary batteries, which include a solid electrolyte, do not suffer from the problems caused by flammable organic electrolytes that exist in liquid lithium-ion secondary batteries. This solid electrolyte is primarily composed of an ion conductor capable of ion conduction within a solid state. Furthermore, all-solid-state lithium-ion secondary batteries can achieve significant increases in output density and energy density when using high-potential, high-capacity positive electrode materials and high-capacity negative electrode materials.

[0004] Previously, as a type of all-solid-state lithium-ion secondary battery, there was a so-called lithium deposition type all-solid-state lithium-ion secondary battery in which lithium metal was deposited onto the negative electrode current collector during charging. Due to this structure, the following problems exist: during charging, dendrites grow on the negative electrode current collector, resulting in reduced battery capacity or short circuits.

[0005] A lithium secondary battery (e.g., according to International Publication No. 2023 / 218218) is designed to suppress the dendrite growth of lithium deposited on the negative electrode current collector during charging. At least a portion of the region on the main surface of the solid electrolyte layer opposite the negative electrode current collector, and the region on the positive electrode active material layer opposite the negative electrode current collector, is provided with an ion conductivity reaction suppression layer. This ion conductivity reaction suppression layer has lithium ion conductivity and suppresses the reaction between lithium metal and the solid electrolyte. On the positive electrode side of the solid electrolyte layer, the solid electrolyte layer extends to the end in the planar direction. On the end in the planar direction of the negative electrode side of the solid electrolyte layer, an ion permeation suppression layer is provided to suppress the permeation of lithium ions. At least a portion of the ion permeation suppression layer overlaps with the ion conductivity reaction suppression layer when viewed from above. Summary of the Invention

[0006] During the fabrication of all-solid-state lithium-ion secondary batteries, cracks sometimes occur on the sides of the solid electrolyte layer. The following issues exist: ionic conductivity decreases at the cracked sides of the solid electrolyte layer, leading to a reduction in the rate characteristics of the all-solid-state lithium-ion secondary battery. Furthermore, the cracked sides of the solid electrolyte layer become sites where lithium easily deposits. While dendrite growth was suppressed in International Publication No. 2023 / 218218, there is room for improvement in suppressing crack formation on the sides of the solid electrolyte layer.

[0007] The present invention provides an all-solid-state battery that suppresses cracking on the sides of the solid electrolyte layer and inhibits lithium deposition on the sides of the solid electrolyte layer. The present invention contributes to the stabilization of battery performance and the improvement of energy efficiency.

[0008] The present invention has the following solution.

[0009] [1] An all-solid-state battery comprising a positive electrode layer, a solid electrolyte layer, and a negative electrode layer, wherein,

[0010] The solid electrolyte layer contains solid electrolyte particles with a particle size of less than 1 μm at least at its ends in a direction orthogonal to the stacking direction of the positive electrode layer, the solid electrolyte layer, and the negative electrode layer.

[0011] The density of the solid electrolyte layer is 1.90 g / cm³ at least at its ends in a direction orthogonal to the stacking direction. 3 above.

[0012] According to the above scheme, in the solid electrolyte layer, at least at the ends in the direction orthogonal to the stacking direction of the positive electrode layer, the solid electrolyte layer and the negative electrode layer, the contact area between the solid electrolyte particles is increased, thus improving the ionic conductivity of the solid electrolyte layer.

[0013] [2] According to the all-solid-state battery described in [1] or [2], wherein,

[0014] The solid electrolyte layer does not contain solid electrolyte particles with a particle size larger than 1 μm at least at its end in a direction orthogonal to the stacking direction.

[0015] According to the above scheme, the solid electrolyte particles contained in the solid electrolyte layer become only microparticles, thus further improving the ionic conductivity of the solid electrolyte layer.

[0016] [3] According to the all-solid-state battery described in [1] or [2], wherein,

[0017] The solid electrolyte layer includes a binder, and the binder content is 3% by weight or more relative to the total weight of the solid electrolyte layer.

[0018] According to the above scheme, the density of the solid electrolyte layer is increased, thereby further improving the ionic conductivity of the solid electrolyte layer. In addition, the mechanical strength of the solid electrolyte layer is improved.

[0019] [4] The all-solid-state battery according to any one of [1] to [3], wherein,

[0020] The solid electrolyte layer has a positive electrode opposing region at least at its end in a direction orthogonal to the stacking direction, which is opposite to the positive electrode layer.

[0021] The specific surface area of ​​the solid electrolyte layer on the positive electrode side in the positive electrode opposing region is 548 m². 2 / g or more.

[0022] According to the above scheme, even when the positive electrode layer is made denser (higher density) than the solid electrolyte layer, the bonding strength of the solid electrolyte layer relative to the positive electrode layer is improved.

[0023] [5] The all-solid-state battery according to any one of [1] to [4], wherein,

[0024] The solid electrolyte layer has a positive electrode opposing region at least at its end in a direction orthogonal to the stacking direction, which is opposite to the positive electrode layer.

[0025] The positive electrode layer has a tapered region at its end in a direction orthogonal to the stacking direction, where its thickness decreases towards the outer periphery of the positive electrode layer.

[0026] The positive electrode opposing region is opposite to the conical region in the stacking direction.

[0027] According to the above scheme, the solid electrolyte layer, which includes small-sized solid electrolyte particles, is positioned opposite the conical region of varying thickness in the positive electrode layer, which can suppress the formation of gaps between the positive electrode layer and the solid electrolyte layer. Furthermore, it can suppress the decrease in ionic conductivity in both the positive electrode layer and the solid electrolyte layer.

[0028] [6] The all-solid-state battery according to any one of [1] to [5], wherein,

[0029] The all-solid-state battery mentioned above is an all-solid-state battery that utilizes the precipitation and dissolution reaction of lithium.

[0030] Furthermore, the all-solid-state battery has an intermediate layer between the solid electrolyte layer and the negative electrode layer, and this intermediate layer contains particles with a particle size of less than 0.5 μm.

[0031] The solid electrolyte layer has an intermediate layer opposing region at least at its end in a direction orthogonal to the stacking direction, which is opposite to the intermediate layer.

[0032] According to the above scheme, although the thickness of the intermediate layer is thin and the particle size of the particles is small, the density of the solid electrolyte layer is high, so the structure of the intermediate layer is stable.

[0033] [7] The all-solid-state battery according to any one of [1] to [6], wherein,

[0034] The solid electrolyte layer has an extension that extends beyond the positive electrode layer and the negative electrode layer in a direction orthogonal to the stacking direction.

[0035] According to the above scheme, the high-density solid electrolyte layer is extended to a position further outward than the positive and negative electrode layers, thus improving the insulation of the positive and negative electrode layers obtained based on the solid electrolyte layer.

[0036] [8] The all-solid-state battery according to any one of [1] to [7], wherein,

[0037] The density of the solid electrolyte layer at its outer peripheral end is 1.90 g / cm³. 3 above.

[0038] According to the above scheme, the solid electrolyte layer is formed in the entire peripheral region of the positive electrode layer and the negative electrode layer (both the long side and the short side of the positive electrode layer and the negative electrode layer).

[0039] [9] According to the all-solid-state battery described in [8], wherein,

[0040] The length of the outer periphery of the solid electrolyte layer in one of the directions orthogonal to the stacking direction is larger than the length of the outer periphery of the solid electrolyte layer in the other direction orthogonal to the stacking direction.

[0041] The density of the solid electrolyte layer on the outer periphery of the other side is 1.90 g / cm³. 3 The distance between the above regions is greater than the density of the solid electrolyte layer on the outer periphery of one of the regions, which is 1.90 g / cm³. 3 The distances between the above areas are long.

[0042] According to the above scheme, the solid electrolyte layer can be easily formed in the entire peripheral area of ​​the positive and negative electrode layers (both the long and short sides of the positive and negative electrode layers).

[0043]

[10] The all-solid-state battery according to any one of [1] to [9], wherein,

[0044] The ionic conductivity of the solid electrolyte layer is above 1.00 mS / cm.

[0045] According to the above scheme, the solid electrolyte layer has excellent ionic conductivity.

[0046] The present invention provides an all-solid-state battery that suppresses cracking on the sides of the solid electrolyte layer and suppresses lithium deposition on the sides of the solid electrolyte layer. Attached Figure Description

[0047] Figure 1 This is a top view showing an all-solid-state battery according to one embodiment of the present invention.

[0048] Figure 2 This refers to an all-solid-state battery according to an embodiment of the present invention and along... Figure 1 A cross-sectional view along line AA.

[0049] Figure 3 This is a top view showing an all-solid-state battery according to one embodiment of the present invention.

[0050] Figure 4 This is a scanning electron microscope (SEM) image of a cross-section in the thickness direction of the solid electrolyte layer obtained in Example 1.

[0051] Figure 5 This is a scanning electron microscope (SEM) image of a cross-section in the thickness direction of the solid electrolyte layer obtained in Example 2.

[0052] Figure 6 This is a scanning electron microscope (SEM) image of a cross-section in the thickness direction of the solid electrolyte layer obtained in the comparative example. Detailed Implementation

[0053] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0054] [All-solid-state battery]

[0055] Figure 1 This is a top view showing an all-solid-state battery according to one embodiment of the present invention. Figure 2 This refers to an all-solid-state battery according to an embodiment of the present invention and along... Figure 1 A cross-sectional view along line AA. Figure 3 This is a top view showing an all-solid-state battery according to one embodiment of the present invention.

[0056] like Figure 1 and Figure 2 As shown, the all-solid-state battery 1 of this embodiment includes a positive electrode layer 10, a solid electrolyte layer 20, and a negative electrode layer 30. Furthermore, the all-solid-state battery 1 of this embodiment includes a current collector 40 connected to the positive current collector 11 constituting the positive electrode layer 10 and the negative current collector 31 constituting the negative electrode layer 30. The positive electrode layer 10 includes the positive current collector 11 and the positive active material layer 12. The negative electrode layer 30 includes the negative current collector 31 and the negative active material layer 32.

[0057] The thickness of the solid electrolyte layer 20 is preferably 200 μm or more and 300 μm or less, more preferably 100 μm or more and 150 μm or less, and even more preferably 15 μm or more and 20 μm or less.

[0058] The solid electrolyte layer 20 contains solid electrolyte particles with a particle size of 1 μm or less at least at its end 21 in a direction orthogonal to the stacking direction of the positive electrode layer 10, the solid electrolyte layer 20, and the negative electrode layer 30. It should be noted that the solid electrolyte layer 20 may also consist entirely of solid electrolyte particles with a particle size of 1 μm or less. By using solid electrolyte particles with a particle size of 1 μm or less, the contact area between the solid electrolyte particles is increased, thereby improving the ionic conductivity of the solid electrolyte layer.

[0059] Preferably, the solid electrolyte layer 20 does not contain solid electrolyte particles with a particle size larger than 1 μm at least at its end 21 in a direction orthogonal to the stacking direction of the positive electrode layer 10, the solid electrolyte layer 20, and the negative electrode layer 30. Thus, the solid electrolyte particles contained in the solid electrolyte layer 20 become only microparticles, thereby further improving the ionic conductivity of the solid electrolyte layer 20.

[0060] The particle size of solid electrolyte particles can be determined by particle size distribution measurement.

[0061] The density of the solid electrolyte layer 20 at least at its end 21 in a direction orthogonal to the stacking direction of the positive electrode layer 10, the solid electrolyte layer 20, and the negative electrode layer 30 is 1.90 g / cm³. 3 That's all. It should be noted that the solid electrolyte layer 20 can also have an overall density of 1.90 g / cm³. 3 The density of the solid electrolyte layer 20 is 1.90 g / cm³. 3 As a result, the contact area between the solid electrolyte particles increases, thus improving the ionic conductivity of the solid electrolyte layer 20. Furthermore, the mechanical strength (e.g., tensile strength) of the solid electrolyte layer 20 is also improved.

[0062] The density of the solid electrolyte layer 20 can be determined by the BET method.

[0063] The solid electrolyte layer 20 preferably includes a binder. The binder content relative to the total weight (100% by weight) of the solid electrolyte layer 20 is preferably 3% by weight or more, more preferably 20% by weight or more, and even more preferably 30% by weight or more. When the binder content is at or above the aforementioned lower limit, the density of the solid electrolyte layer 20 increases, thereby further improving the ionic conductivity of the solid electrolyte layer 20. Furthermore, the mechanical strength of the solid electrolyte layer 20 is improved.

[0064] The amount of binder relative to the total weight (100% by weight) of the solid electrolyte layer 20 can be less than 3% by weight, less than 1% by weight, or less than 0.1% by weight.

[0065] The solid electrolyte layer 20 preferably has a positive electrode opposing region 21A at its end 21, in a direction orthogonal to the stacking direction of the positive electrode layer 10, the solid electrolyte layer 20, and the negative electrode layer 30, opposite to the positive electrode layer 10. The specific surface area of ​​the solid electrolyte layer 20 on the positive electrode layer 10 side in the positive electrode opposing region 21A is preferably 1025 m². 2 / g or more, preferably 1184m 2 / g or more, further preferably 1343m 2 / g or more. When the specific surface area of ​​the solid electrolyte layer 20 in the positive electrode opposing region 21A is above the lower limit value, even when the positive electrode layer 10 is made denser (higher density) than the solid electrolyte layer 20, the bonding strength of the solid electrolyte layer 20 with respect to the positive electrode layer 10 is improved.

[0066] The specific surface area of ​​the solid electrolyte layer 20 on the positive electrode layer 10 side in the positive electrode opposing region 21A can be 1343 m². 2 Below / g, or 1000m 2 Below / g, it can also be 500m 2 / g or less.

[0067] The specific surface area of ​​the solid electrolyte layer 20 in the positive electrode opposing region 21A can be determined by the BET method.

[0068] The solid electrolyte layer 20 preferably has a positive electrode opposing region 21A at its end 21 in a direction orthogonal to the stacking direction of the positive electrode layer 10, the solid electrolyte layer 20, and the negative electrode layer 30, which is opposite to the positive electrode layer 10. The positive electrode layer 10 preferably has a conical region 12B at its end in a direction orthogonal to the stacking direction, in other words, at the end 12A of the positive electrode active material layer 12, where the thickness decreases towards the outer periphery of the positive electrode layer 10. The positive electrode opposing region 21A is opposite to the conical region 12B in the stacking direction. Thus, by opposing the solid electrolyte layer 20, which contains small solid electrolyte particles, to the conical region in the positive electrode layer 10 where the thickness is not constant, gaps between the positive electrode layer 10 (positive electrode active material layer 12) and the solid electrolyte layer 20 can be suppressed. Furthermore, the decrease in ionic conductivity in the positive electrode layer 10 (positive electrode active material layer 12) and the solid electrolyte layer 20 can be suppressed.

[0069] The all-solid-state battery 1 of this embodiment is preferably an all-solid-state battery utilizing the lithium precipitation-dissolution reaction. In this case, the all-solid-state battery 1 of this embodiment preferably also includes an intermediate layer 50 containing particles with a particle size of 0.5 μm or less between the solid electrolyte layer 20 and the negative electrode layer 30. When the particle size of the particles contained in the intermediate layer 50 is below the upper limit value, although the thickness of the intermediate layer 50 is thin and the particle size is small, the density of the solid electrolyte layer 20 is high, and therefore the structure of the intermediate layer 50 is stable.

[0070] The particle size of the above-mentioned particles can be determined by particle size distribution measurement.

[0071] Furthermore, the solid electrolyte layer 20 preferably has an intermediate layer opposing region 21B at its end 21 in a direction orthogonal to the stacking direction of the positive electrode layer 10, the solid electrolyte layer 20, and the negative electrode layer 30, which is opposite to the intermediate layer 50. By having the intermediate layer opposing region 21B, although the thickness of the intermediate layer 50 is thin and the particle size is small, the density of the solid electrolyte layer 20 is high, thus the structure of the intermediate layer 50 is stable.

[0072] The thickness of the intermediate layer 50 is preferably 2.7 μm or more and 3.3 μm or less, more preferably 1.8 μm or more and 2.2 μm or less, and even more preferably 0.9 μm or more and 1.1 μm or less. When the thickness of the intermediate layer 50 is above the lower limit, it is beneficial to the diffusion of lithium ions, and a rectifying effect can be expected. When the thickness of the intermediate layer 50 is below the upper limit, it becomes low-resistance.

[0073] The solid electrolyte layer 20 preferably has an extension 22 that extends beyond the positive electrode layer 10 and the negative electrode layer 30 in a direction orthogonal to the stacking direction of the positive electrode layer 10, the solid electrolyte layer 20, and the negative electrode layer 30. By having the extension 22, the high-density solid electrolyte layer 20 is extended to a position further outward than the positive electrode layer 10 and the negative electrode layer 30, thereby improving the insulation of the positive electrode layer 10 and the negative electrode layer 30 based on the solid electrolyte layer 20.

[0074] The density of the solid electrolyte layer 20 at its outer peripheral end 21 is preferably 1.90 g / cm³. 3 The above, more preferably 1.92 g / cm³ 3 The above is further optimized to 1.93 g / cm³. 3 The above. When the density of the solid electrolyte layer 20 at the end 21 in the outer peripheral direction is above the lower limit value, it is formed in the entire outer peripheral region of the positive electrode layer 10 and the negative electrode layer 30 (both the long side direction and the short side direction of the positive electrode layer 10 and the negative electrode layer 30).

[0075] Preferably, the length of the outer periphery of one of the directions orthogonal to the stacking directions of the positive electrode layer 10, the solid electrolyte layer 20, and the negative electrode layer 30 is ( Figure 1 Compared to the length L1 of the long side of the solid electrolyte layer 20 shown, the length of the outer periphery of the solid electrolyte layer 20 in the direction orthogonal to the stacking direction is ( Figure 1 The length L2 of the short side of the solid electrolyte layer 20 shown is relatively large. As a result, the solid electrolyte layer 20 can be easily formed in the entire peripheral region of the positive electrode layer 10 and the negative electrode layer 30 (both the long side and the short side of the positive electrode layer 10 and the negative electrode layer 30).

[0076] Moreover, such as Figure 3 As shown, preferably, the density of the solid electrolyte layer 20 on the outer periphery of the other side is 1.90 g / cm³. 3 The distance d1 of the above-mentioned region is 1.90 g / cm³ compared to the density of the solid electrolyte layer 20 on the outer periphery of the aforementioned side. 3 The distance d2 in the above region is long. As a result, the solid electrolyte layer 20 can be easily formed in the entire peripheral region of the positive electrode layer 10 and the negative electrode layer 30 (both the long side direction and the short side direction of the positive electrode layer 10 and the negative electrode layer 30).

[0077] The ionic conductivity of the solid electrolyte layer 20 is preferably 1.00 mS / cm or higher, more preferably 1.05 mS / cm or higher, and even more preferably 1.10 mS / cm or higher. When the ionic conductivity of the solid electrolyte layer 20 is above the aforementioned lower limit value, the ionic conductivity of the solid electrolyte layer 20 is excellent.

[0078] The ionic conductivity of the solid electrolyte layer 20 can be measured by impedance measurement.

[0079] (Positive electrode layer)

[0080] The positive electrode layer 10 includes a positive current collector 11 and a positive electrode active material layer 12. For example, aluminum can be used as the material for the positive electrode active material layer 12. The positive electrode active material layer 12 contains a positive electrode active material. Examples of positive electrode active materials include lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), and LiNi... p Mn q Co r O2 (p+q+r=1), LiNi p Al q Co r O2 (p+q+r=1), lithium manganese oxide (LiMn2O4), Li 1+x Mn 2-x-y M y The positive electrode active material layer may also include various additives used as materials for the positive electrode active material layer 12, such as binders and conductive additives. These additives may be represented by O4 (x+y=2, M=at least one selected from Al, Mg, Co, Fe, Ni, and Zn), which represent different elemental substitutions such as Li-Mn spinel, lithium titanate (an oxide containing Li and Ti), and lithium metal phosphate (LiMPO4, M=at least one selected from Fe, Mn, Co, and Ni).

[0081] (Negative electrode layer)

[0082] The negative electrode layer 30 includes a negative electrode current collector 31 and a negative electrode active material layer 32. For example, copper can be used as the material for the negative electrode active material layer 32. The negative electrode active material layer 32 contains a negative electrode active material. Lithium or a metal alloyed with lithium can be used as the negative electrode active material. Examples of metals alloyed with lithium include Mg, Si, Au, Ag, In, Ge, Sn, Pb, Al, and Zn. Alternatively, carbonaceous materials can be included as the negative electrode active material. Examples of carbonaceous materials include natural graphite, artificial graphite, mesophase carbon microspheres (MCMB), hard carbon, and soft carbon.

[0083] (Solid electrolyte layer)

[0084] As the solid electrolyte included in the solid electrolyte layer 20, a sulfide-based solid electrolyte can be used, for example. Examples of sulfide-based solid electrolytes include Li₂S-P₂S₅, Li₂S-P₂S₅-LiI, Li₂S-P₂S₅-Li₂O, Li₂S-P₂S₅-Li₂O-LiI, LiS-SiS₂, Li₂S-SiS₂-Li, Li₂S-SiS₂-LiBr, Li₂S-SiS₂-LiCl, Li₂S-SiS₂-B₂S₃-LiI, Li₂S-SiS₂-P₂S₅-LiI, Li₂S-B₂S₃, and Li₂S-P₂S₅-Z. m S n (Where m and n are positive numbers. Z is any one of Ge, Zn, and Ga.) Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li x MO y (Where x and y are positive numbers. M is any one of P, Si, Ge, B, Al, Ga, and In.) etc.

[0085] (Intermediate layer)

[0086] The material used to form the intermediate layer 50 is not particularly limited.

[0087] According to the all-solid-state battery 1 of this embodiment, the contact area between solid electrolyte particles in the solid electrolyte layer 20 is increased at least at the end 21 in the direction orthogonal to the stacking direction of the positive electrode layer 10, the solid electrolyte layer 20 and the negative electrode layer 30, thereby improving the ionic conductivity of the solid electrolyte layer 20.

[0088] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the above embodiments. Various modifications and alterations can be made within the scope of the spirit of the present invention described in the technical solution.

[0089]

Example

[0090] The present invention will be described in more detail below with reference to the embodiments, but the present invention is not limited to the following embodiments.

[0091] [Example 1]

[0092] A solid electrolyte slurry containing solid electrolyte particles with a particle size of 3 μm (hereinafter referred to as "solid electrolyte particle A") and solid electrolyte particles with a particle size of 0.7 μm (hereinafter referred to as "solid electrolyte particle B") was coated onto an aluminum foil. The slurry was then dried, forming a solid electrolyte layer on the aluminum foil containing solid electrolyte particles A and B in a mass ratio of 8:2. The resulting solid electrolyte layer was compressed under a pressure of 800 MPa, yielding a density of 1.93 g / cm³. 3 It is a solid electrolyte layer with a porosity of 0.12%.

[0093] A scanning electron microscope (SEM) image of the cross-section along the thickness direction of the obtained solid electrolyte layer is shown in... Figure 4 .like Figure 4 As shown, it can be seen that, regarding the obtained solid electrolyte layer, solid electrolyte particles B fill the gaps between solid electrolyte particles A, thus forming a dense layer.

[0094] [Example 2]

[0095] A solid electrolyte slurry containing solid electrolyte particles B was coated onto an aluminum foil, and the slurry was dried to form a solid electrolyte layer containing solid electrolyte particles B on the aluminum foil. The resulting solid electrolyte layer was compressed under a pressure of 800 MPa to obtain a density of 1.93 g / cm³. 3 It is a solid electrolyte layer with a porosity of 0.10%.

[0096] A scanning electron microscope (SEM) image of the cross-section along the thickness direction of the obtained solid electrolyte layer is shown in... Figure 5 .like Figure 5 As shown, the obtained solid electrolyte layer is a dense layer composed only of solid electrolyte particles B.

[0097] [Comparative Example]

[0098] A solid electrolyte slurry containing solid electrolyte particles A was coated onto an aluminum foil, and the slurry was dried to form a solid electrolyte layer containing solid electrolyte particles A on the aluminum foil. The resulting solid electrolyte layer was compressed under a pressure of 800 MPa to obtain a density of 1.88 g / cm³. 3 It is a solid electrolyte layer with a porosity of 2.57%.

[0099] A scanning electron microscope (SEM) image of the cross-section along the thickness direction of the obtained solid electrolyte layer is shown in... Figure 6 .like Figure 6 As shown, the obtained solid electrolyte layer is a non-dense layer composed only of solid electrolyte particles A.

Claims

1. An all-solid-state battery comprising a positive electrode layer, a solid electrolyte layer, and a negative electrode layer, wherein, The solid electrolyte layer contains solid electrolyte particles with a particle size of less than 1 μm at least at its ends in a direction orthogonal to the stacking direction of the positive electrode layer, the solid electrolyte layer, and the negative electrode layer. The density of the solid electrolyte layer is 1.90 g / cm³ at least at its ends in a direction orthogonal to the stacking direction. 3 above.

2. The all-solid-state battery according to claim 1, wherein, The solid electrolyte layer does not contain solid electrolyte particles with a particle size larger than 1 μm at least at its end in a direction orthogonal to the stacking direction.

3. The all-solid-state battery according to claim 1, wherein, The solid electrolyte layer includes a binder, and the binder content is 3% by weight or more relative to the total weight of the solid electrolyte layer.

4. The all-solid-state battery according to claim 1, wherein, The solid electrolyte layer has a positive electrode opposing region at least at its end in a direction orthogonal to the stacking direction, which is opposite to the positive electrode layer. The specific surface area of ​​the solid electrolyte layer on the positive electrode side in the positive electrode opposing region is 548 m². 2 / g or more.

5. The all-solid-state battery according to claim 1, wherein, The solid electrolyte layer has a positive electrode opposing region at least at its end in a direction orthogonal to the stacking direction, which is opposite to the positive electrode layer. The positive electrode layer has a tapered region with decreasing thickness at its end in a direction orthogonal to the stacking direction. The positive electrode opposing region is opposite to the conical region in the stacking direction.

6. The all-solid-state battery according to claim 1, wherein, The all-solid-state battery mentioned above is an all-solid-state battery that utilizes the precipitation and dissolution reaction of lithium. Furthermore, the all-solid-state battery has an intermediate layer between the solid electrolyte layer and the negative electrode layer, and this intermediate layer contains particles with a particle size of less than 0.5 μm. The solid electrolyte layer has an intermediate layer opposing region at least at its end in a direction orthogonal to the stacking direction, which is opposite to the intermediate layer.

7. The all-solid-state battery according to claim 1, wherein, The solid electrolyte layer has an extension that extends beyond the positive electrode layer and the negative electrode layer in a direction orthogonal to the stacking direction.

8. The all-solid-state battery according to claim 1, wherein, The density of the solid electrolyte layer at its outer peripheral end is 1.90 g / cm³. 3 above.

9. The all-solid-state battery according to claim 8, wherein, The length of the outer periphery of the solid electrolyte layer in one of the directions orthogonal to the stacking direction is larger than the length of the outer periphery of the solid electrolyte layer in the other direction orthogonal to the stacking direction. The density of the solid electrolyte layer on the outer periphery of the other side is 1.90 g / cm³. 3 The distance between the above regions is greater than the density of the solid electrolyte layer on the outer periphery of one of the regions, which is 1.90 g / cm³. 3 The distances between the above areas are long.

10. The all-solid-state battery according to any one of claims 1 to 9, wherein, The ionic conductivity of the solid electrolyte layer is above 1.00 mS / cm.

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