Batteries and lithium-ion batteries

Abstract

A battery is provided that can suppress the occurrence of cracks in the solid electrolyte layer. [Solution] The battery comprises a positive electrode, a solid electrolyte layer, and a negative electrode, in this order along a first direction. The battery has at least one of the positive electrode and the negative electrode, which comprises a plurality of cylindrical first electrode material portions and a plurality of cylindrical second electrode material portions. Viewed from the first direction, the plurality of first electrode material portions are arranged on the central part side of the battery relative to the plurality of second electrode material portions. Two adjacent first electrode material portions and two adjacent second electrode material portions are spaced apart. The diameter of the first electrode material portion is smaller than the diameter of the second electrode material portion.

Description

Technical Field

[0001] The present disclosure relates to batteries and lithium-ion batteries.

Background Art

[0002] In recent years, the development of sulfur batteries using sulfur as a cathode active material has been underway. Sulfur has a high theoretical capacity (i.e., 1675 mAh / g). Patent Document 1 discloses a cathode composite material. The cathode composite material contains a cathode active material containing an S element, a sulfur-containing compound containing a P element and an S element, and a conductive assistant, and substantially does not contain a Li element. The cathode composite material has specific standard values.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in a battery including a cathode composite material layer containing the cathode composite material disclosed in Patent Document 1 and a solid electrolyte layer, due to the volume change (i.e., expansion or contraction) of the cathode active material caused by charging or discharging of the battery, stress is likely to be applied to the solid electrolyte layer. As a result, cracks may occur in the solid electrolyte layer.

[0005] The present disclosure is made in view of the above circumstances. The problem to be solved by one embodiment of the present disclosure is to provide a battery and a lithium-ion battery capable of suppressing the occurrence of cracks in the solid electrolyte layer.

Means for Solving the Problems

[0006] Means for solving the above problems include the following embodiments.

[0007] <1> A battery according to a first aspect of this disclosure is A battery comprising a positive electrode, a solid electrolyte layer, and a negative electrode in this order along a first direction, At least one of the positive electrode and the negative electrode has a plurality of cylindrical first electrode composite portions and a plurality of cylindrical second electrode composite portions, Viewed from the first direction, the plurality of first electrode composite material portions are arranged on the central part side of the battery relative to the plurality of second electrode composite material portions. Two adjacent portions of the multiple first electrode composite material portions and the multiple second electrode composite material portions are arranged with a gap between them. This is a battery in which the diameter of the first electrode composite portion is smaller than the diameter of the second electrode composite portion.

[0008] When viewed from the first direction, the battery reaction in the central part of the battery tends to proceed more easily than in the parts that are not in the center of the battery. In other words, the volume change of at least one of the positive electrode composite material and the negative electrode composite material (hereinafter collectively referred to as the "composite material") in the central part of the battery tends to be larger than in the parts that are not in the center of the battery. When the volume of the composite material changes in the second direction, stress is generated in the solid electrolyte layer in the second direction. Because the first embodiment has the above configuration, the stress in the second direction on the solid electrolyte layer due to volume changes in the composite material is relieved. As a result, the battery of the first embodiment can suppress the occurrence of cracks in the solid electrolyte layer. In addition, in the first embodiment, the volume of voids that do not contribute to the battery reaction can be reduced by adjusting the arrangement of the multiple first electrode composite materials. This can improve the energy density of the battery.

[0009] <2> A battery according to a second aspect of this disclosure is The length of the first electrode composite portion in the first direction and the length of the second electrode composite portion in the first direction are the same. The shortest distance G between the first electrode material portion and the second electrode material portion adjacent to the first electrode material portion is longer than the length of the first electrode material portion in the first direction. <1> This is the battery described in [the document].

[0010] To reduce the interfacial resistance of the positive electrode, solid electrolyte layer, and negative electrode, a constraint pressure is usually applied to the battery in a first direction. This constraint pressure may cause the composite material to collapse and deform (expand in diameter). In the second embodiment, because it has the above configuration, even when a restraining pressure is applied to the battery, the two adjacent composite material parts are less likely to come into physical contact. As a result, the battery of the second embodiment can further suppress the occurrence of cracks in the solid electrolyte layer.

[0011] <3> A battery according to a third aspect of this disclosure is The shortest interval G is longer than twice the amount of expansion of the second electrode composite material, <2> This is the battery described in [the document].

[0012] In this disclosure, the "amount of expansion of the second electrode composite material" is expressed as the product of the intrinsic expansion rate of the constituent elements of the second electrode composite material and the diameter of the second electrode composite material.

[0013] In the third embodiment, because it has the above configuration, two adjacent composite material parts are less likely to come into physical contact. As a result, the battery of the third embodiment can further suppress the occurrence of cracks in the solid electrolyte layer.

[0014] <4> A lithium-ion battery according to a fourth aspect of this disclosure is A lithium-ion battery comprising a positive electrode, a solid electrolyte layer, and a negative electrode in this order along a first direction, At least one of the positive electrode or the negative electrode has a plurality of cylindrical first electrode composite parts and a plurality of cylindrical second electrode composite parts, Multiple first electrode composite material portions are arranged relative to multiple second electrode composite material portions on the central side of the lithium-ion battery as viewed from the first direction. Two adjacent portions of the multiple first electrode composite material portions and the multiple second electrode composite material portions are arranged with a gap between them. The diameter of the first electrode composite portion is smaller than the diameter of the second electrode composite portion. The lithium ion battery is such that when the positive electrode or the negative electrode occludes lithium almost maximally, the interval is an interval in which two adjacent ones of the plurality of first electrode composite parts and the plurality of second electrode composite parts do not contact each other.

[0015] In the present disclosure, "when the positive electrode occludes carrier ions almost maximally" indicates the time when the state of charge (SOC) of the battery is 0%. "When the negative electrode occludes carrier ions almost maximally" indicates the time when the SOC is 100%.

[0016] The Young's modulus of the positive electrode active material containing sulfur is low. In a lithium ion battery using a positive electrode active material containing sulfur, when the lithium ion battery is constrained, the positive electrode composite part is likely to collapse and deform (likely to expand in diameter). Since the fourth aspect has the above configuration, even when a constraint pressure is applied to the lithium ion battery, two adjacent composite parts are unlikely to physically contact each other. As a result, the lithium ion battery of the fourth aspect can further suppress the generation of cracks in the solid electrolyte layer.

Advantages of the Invention

[0017] According to the present disclosure, there are provided a battery and a lithium ion battery capable of suppressing the generation of cracks in the solid electrolyte layer.

Brief Description of the Drawings

[0018] [Figure 1] FIG. 1 is a cross-sectional view of a battery according to the first embodiment. [Figure 2] FIG. 2 is a top view of the positive electrode composite part and the solid electrolyte layer of the battery according to the first embodiment. [Figure 3] FIG. 3 is a cross-sectional view of a battery according to the second embodiment. [Figure 4] FIG. 4 is a cross-sectional view of the battery of Reference Example 2. [Figure 5] FIG. 5 is a top view of the positive electrode composite part and the solid electrolyte layer of the battery of Reference Example 2.

Modes for Carrying Out the Invention

[0019] In this disclosure, a numerical range indicated using "~" means a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. In numerical ranges described in stages in this disclosure, the upper or lower limit stated in one numerical range may be replaced by the upper or lower limit of another numerical range described in stages. In this disclosure, a combination of two or more preferred embodiments is a more preferred embodiment. In this disclosure, the term "process" is included not only in the sense of an independent process, but also in the sense of a process that is not clearly distinguishable from other processes, as long as its intended purpose is achieved.

[0020] (1) First Embodiment The battery 1A of the first embodiment is a monopolar lithium-ion battery. As shown in Figure 1, the battery 1A comprises a positive electrode 10A, a solid electrolyte layer 20, a negative electrode 30, and an outer casing 40. The positive electrode 10A, the solid electrolyte layer 20, and the negative electrode 30 are stacked in this order. The outer casing 40 houses the positive electrode 10A, the solid electrolyte layer 20, and the negative electrode 30. The battery 1A is a rectangular parallelepiped.

[0021] In the first embodiment, the stacking direction of the positive electrode 10A, the solid electrolyte layer 20, and the negative electrode 30 is defined as the X-axis direction (an example of the first direction). The direction perpendicular to the X-axis direction is defined as the Y-axis direction (an example of the second direction). The direction perpendicular to both the X-axis and Y-axis directions is defined as the Z-axis direction (an example of the second direction). Note that these directions do not limit the orientation of the battery when it is used.

[0022] (1.1) Positive electrode The positive electrode 10A includes a plurality of first positive electrode composite material portions 11a (an example of a first electrode composite material portion), a plurality of second positive electrode composite material portions 11b (an example of a second electrode composite material portion), and a positive electrode current collector 12. The plurality of first positive electrode composite material portions 11a and the plurality of second positive electrode composite material portions 11b are arranged on one main surface S12 of the positive electrode current collector 12.

[0023] Hereinafter, the multiple first positive electrode composite material sections 11a and the multiple second positive electrode composite material sections 11b will be collectively referred to as the "positive electrode composite material section".

[0024] (1.1.1) Positive electrode composite section As shown in Figure 2, the positive electrode composite material is arranged in a 45-degree staggered pattern.

[0025] Viewed from the X-axis direction, the multiple first positive electrode composite material portions 11a are positioned relative to the multiple second positive electrode composite material portions 11b on the central side of the battery 1A (in other words, the central side of the main surface S20 of the solid electrolyte layer 20). In other words, the multiple first positive electrode composite material portions 11a are positioned in the central part of the battery 1A, and the multiple second positive electrode composite material portions 11b are positioned so as to surround the multiple first positive electrode composite material portions 11a.

[0026] Two adjacent first cathode composite material portions 11a and two adjacent second cathode composite material portions 11b are arranged with a gap between them. In the first embodiment, the portion R (see Figure 1) between two adjacent first cathode composite material portions 11a and two adjacent second cathode composite material portions 11b is a void.

[0027] The length of the first positive electrode composite material section 11a in the first direction and the length of the second positive electrode composite material section 11b in the first direction are the same length H (see Figure 1). The shortest distance G (see Figure 2) between the first positive electrode composite material section 11a and the second positive electrode composite material section 11b is longer than the length H in the X-axis direction of the first positive electrode composite material section 11a. The shortest distance G is longer than twice the expansion amount α of the second positive electrode composite material section 11b. The shortest distance Ga (see Figure 2) and the shortest distance Gb (see Figure 2) between adjacent first positive electrode composite material sections 11a are the same as the shortest distance G.

[0028] The shortest intervals G, Ga, and Gb are the intervals at which two adjacent positive electrode composite material sections do not come into contact when the positive electrode 10A has absorbed approximately its maximum amount of lithium.

[0029] The first positive electrode composite material portion 11a and the second positive electrode composite material portion 11b are cylindrical in shape. The diameter D11a of the first positive electrode composite material portion 11a (see Figure 2) is smaller than the diameter D11b of the second positive electrode composite material portion 11b (see Figure 2). The diameter D11b may be between 0.10 mm and 1 mm, or between 0.10 mm and 0.35 mm.

[0030] The porosity of the electrode mixture is not particularly limited, but is preferably 40% to 90% from the viewpoint of suppressing the occurrence of cracks in the solid electrolyte layer 20. The porosity of the electrode mixture is preferably 70% to 80% from the viewpoint of suppressing the occurrence of cracks in the solid electrolyte layer 20 and ensuring sufficient energy density of the battery. "Porosity of the electrode mixture" refers to the ratio of the total area of ​​voids within the electrode mixture formation region to the area of ​​the electrode mixture formation region when viewed from a first direction. "Formation region of the electrode mixture" refers to the minimum area region that encompasses the entirety of the multiple outermost second electrode mixture sections when viewed from a first direction, and is a rectangular (i.e., square or rectangular), circular or elliptical region. In the first embodiment, "Formation region R11 of the electrode mixture" refers to the minimum area region that encompasses the entirety of the multiple outermost second positive electrode mixture sections 11b when viewed from the X-axis direction, and is a rectangular region.

[0031] The positive electrode composite material contains positive electrode active material (e.g., elemental sulfur, LiCoO2, LiMn2O4, and LiFePO4). The positive electrode composite material may further contain, as needed, sulfur-containing compounds (e.g., P2S5, GeS2, SnS2, SiS2, B2S3, and Al2S3), solid electrolytes (e.g., sulfide solid electrolytes, oxide solid electrolytes, and halogenated solid electrolytes), conductive materials (e.g., acetylene black, metal particles, and conductive polymers), and binders (e.g., styrene-butadiene rubber and polyvinylidene fluoride).

[0032] The method for forming the positive electrode composite material is not particularly limited, and examples include method (a1) and method (a2). In method (a1), the slurry of the positive electrode composite material is passed through a mesh having a predetermined shape and size to form a coating on the main surface S12 of the positive electrode current collector 12, and then the coating is dried. In method (a2), a positive electrode composite material layer is formed on the main surface S12 of the positive electrode current collector 12, and the positive electrode composite material layer is trimmed by irradiation with a laser (for example, an ultrashort pulse laser).

[0033] (1.1.2) Positive electrode current collector Examples of materials for the positive electrode current collector 12 include aluminum, copper, stainless steel, and nickel. The shape of the positive electrode current collector 12 may be, for example, foil-like or mesh-like.

[0034] (1.2) Solid electrolyte The solid electrolyte layer 20 contains a solid electrolyte (e.g., sulfide solid electrolyte, oxide solid electrolyte, and halogenated solid electrolyte), and may further contain a binder (e.g., styrene-butadiene rubber and polyvinylidene fluoride) as needed.

[0035] The solid electrolyte layer 20 may have a Li-X alloy interface layer (where X is Mg, Sn, Zn, or Al) at its interface with the negative electrode 30. It is known that when the solid electrolyte layer 20 and metallic lithium come into physical contact during the charging and discharging of a 1A battery, a reductive decomposition reaction of the solid electrolyte layer 20 proceeds. If the reductive decomposition reaction of the solid electrolyte layer 20 proceeds, there is a risk that a layer that acts as an interfacial resistance (hereinafter also referred to as the "resistive layer") will be formed between the solid electrolyte layer 20 and the negative electrode 30. The formation of the resistive layer is suppressed by having a Li-X alloy interface layer in the solid electrolyte layer 20.

[0036] (1.3) Negative electrode The negative electrode 30 comprises a negative electrode composite layer 31 and a negative electrode current collector 32. The negative electrode composite layer 31 is arranged on one main surface S32 of the negative electrode current collector 32.

[0037] The negative electrode composite layer 31 contains a negative electrode active material (for example, metallic lithium, an alloy of metallic lithium and metal X (where X is, for example, Mg, Ag, In, Sn, Si, Ga, Au, and Pt), graphite, lithium titanate, and elemental Si). The negative electrode composite layer may further contain, if necessary, a solid electrolyte (for example, sulfide solid electrolyte, oxide solid electrolyte, and halogenated solid electrolyte), a conductive material (for example, acetylene black, metal particles, and conductive polymer), and a binder (for example, styrene-butadiene rubber and polyvinylidene fluoride). Examples of materials for the negative electrode current collector 32 include aluminum, copper, stainless steel, and nickel. The shape of the negative electrode current collector 32 may be, for example, foil-like or mesh-like.

[0038] (1.4) Exterior Examples of the outer casing 40 include laminate film (e.g., aluminum sheet), battery cans (e.g., cylindrical, rectangular, and coin-shaped), etc.

[0039] (1.5) Effects As described with reference to Figures 1 and 2, the battery 1A comprises a positive electrode 10A, a solid electrolyte layer 20, and a negative electrode 30. The positive electrode 10A has a plurality of cylindrical first positive electrode composite parts 11a and a plurality of cylindrical second positive electrode composite parts 11b. Viewed from the X-axis direction, the plurality of first positive electrode composite parts 11a are positioned towards the central part of the battery 1A relative to the plurality of second positive electrode composite parts 11b. Two adjacent first positive electrode composite parts 11a and second positive electrode composite parts 11b are spaced apart. The diameter D11a of the first positive electrode composite part 11a is smaller than the diameter D11b of the second positive electrode composite part 11b. As a result, the stress on the solid electrolyte layer 20 in the Y-axis and Z-axis directions due to the volume change of the positive electrode composite material 11a is relieved. Consequently, the battery 1B can suppress the occurrence of cracks in the solid electrolyte layer 20.

[0040] As explained with reference to Figures 1 and 2, in battery 1A, the length H of the first positive electrode composite material portion 11a in the X-axis direction is the same as the length H of the second positive electrode composite material portion 11b in the X-axis direction. The shortest distance G is longer than length H. As a result, even when a restraining pressure is applied to the battery 1A, the two adjacent first positive electrode composite material portions 11a are less likely to come into physical contact. In other words, in the first embodiment, a gap exists between the two adjacent positive electrode composite material portions. As a result, the battery 1A can further suppress the occurrence of cracks in the solid electrolyte layer 20.

[0041] As explained with reference to Figures 1 and 2, the shortest interval G is longer than twice the expansion amount of the second positive electrode composite portion 11b. As a result, the two adjacent positive electrode composite material sections are less likely to come into physical contact. Consequently, battery 1A can more effectively suppress the occurrence of cracks in the solid electrolyte layer 20.

[0042] As explained with reference to Figures 1 and 2, the shortest intervals G, Ga, and Gb are the intervals at which two adjacent positive electrode composite material sections do not come into contact when the positive electrode 10A has absorbed approximately its maximum amount of lithium. As a result, even when a restraining pressure is applied to battery 1A in the X-axis direction, the two adjacent positive electrode composite material sections are less likely to come into physical contact. Consequently, battery 1A can further suppress the occurrence of cracks in the solid electrolyte layer 20.

[0043] (2) Second Embodiment The battery 1B of the second embodiment is the same as the battery 1A of the first embodiment, except that a filling material is placed in part R. As shown in Figure 2, the battery 1A comprises a positive electrode 10B, a solid electrolyte layer 20, a negative electrode 30, and an outer casing 40.

[0044] The positive electrode 10B includes a plurality of first positive electrode composite material sections 11a (an example of a first electrode composite material section), a plurality of second positive electrode composite material sections 11b (an example of a second electrode composite material section), a positive electrode current collector 12, and a filler material 13. The filler material 13 is filled into the portion R (see Figure 2) between two adjacent first positive electrode composite material sections 11a and second positive electrode composite material sections 11b.

[0045] The filler material 13 absorbs the elongation in the Y-axis and Z-axis directions of the multiple first positive electrode composite material portions 11a and the multiple second positive electrode composite material portions 11b caused by charging or discharging of the battery 1B. The material of the filler material 13 is a material with a bending strength of 500 MPa or more (preferably 600 MPa or more). Specifically, the material of the filler material 13 is, for example, sapphire.

[0046] Examples of methods for forming the filler material 13 include the first method and the second method. In the first method, the filler material 13, which has been formed to match the shape of part R, is fitted into part R. In the second method, the uncured filler material 13 is poured into part R, and then the uncured filler material 13 is cured.

[0047] Battery 1B is the same as battery 1A, except that the filler material 13 is placed in part R. Therefore, battery 1B has the same effects as battery 1A.

[0048] (3) Variant In the first and second embodiments, the shortest interval G is longer than the length H in the X-axis direction of the first positive electrode composite portion 11a, but the disclosure is not limited thereto. The shortest interval G may be less than or equal to the length H.

[0049] In the first and second embodiments, the shortest interval G is longer than twice the expansion amount α of the second positive electrode composite material portion 11b, but the disclosure is not limited thereto. The shortest interval G may be less than or equal to twice the expansion amount α of the second positive electrode composite material portion 11b.

[0050] Batteries 1A and 1B are lithium-ion batteries, but this disclosure is not limited thereto. The batteries may be alkaline metal ion batteries (e.g., sodium-ion batteries, etc.) and alkaline earth metal batteries, etc.

[0051] Only positive electrodes 10A and 10B have a plurality of first positive electrode composite portions 11a (an example of a first electrode composite portion) and a plurality of second positive electrode composite portions 11b (an example of a second electrode composite portion), but the disclosure is not limited thereto. The plurality of first electrode composite portions and the plurality of second electrode composite portions may be formed only on the negative electrode, or on both the positive and negative electrodes.

[0052] In the first and second embodiments, the positive electrode composite material is arranged in a 45-degree staggered pattern, but the disclosure is not limited thereto. The arrangement pattern of the positive electrode composite material may be a 60-degree staggered pattern, a parallel pattern, a pillar-like pattern, or an irregular pattern.

[0053] In the first and second embodiments, the electrode configuration is a monopolar configuration, but it may be a bipolar configuration. [Examples]

[0054] The present disclosure will be described in more detail below with reference to examples, but the invention of the present disclosure is not limited to these examples.

[0055] [1] Reference example [1.1] Positive electrode Sulfur (S) (80°C vacuum-dried), P2S5, and single-walled carbon nanotubes (120°C vacuum-dried) were mixed in a mortar to obtain a mixture. The mass ratio of these (S:P2S5:Single-walled carbon nanotubes) was 42:35:23. 1.7 g of the mixture and 80 g of zirconia balls (diameter: 4 mm) were placed in each ball mill pot, and milling was performed using a planetary ball mill at 400 rpm (revolutions per minute) for a total of 36 hours. The mixture after milling was classified dry using a 38 μm sieve to obtain a sulfur cathode composite.

[0056] A positive electrode slurry was prepared by mixing a sulfur positive electrode mixture, a binder, and mesitylene as a solvent. The mass ratio (sulfur positive electrode mixture:binder) was 99.7:0.3. The positive electrode slurry was coated onto a roughened aluminum foil, which served as the positive electrode current collector, through a mesh of a predetermined shape and size, with a coating gap of 220 μm. Subsequently, pre-drying was performed at 50°C, followed by final drying at 100°C for 30 minutes to obtain a positive electrode sheet.

[0057] [1.2] Solid electrolyte layer A sulfide solid electrolyte slurry was prepared by mixing a sulfide solid electrolyte (Ver4, 0.5 μm), a binder, and heptane as a solvent. The mass ratio (sulfide solid electrolyte:binder) was 90.9:9.1. The sulfide solid electrolyte slurry was coated onto a release film with a coating gap of 450 μm. The coated material was then pre-dried at room temperature for about 3 hours, and then fully dried at 165°C for 1 hour. A laminated sheet was obtained. The laminated sheet was punched out to obtain two circular laminated sheets (diameter: 14.5 mm). The two circular laminated sheets were stacked so that the sulfide solid electrolyte slurry coated materials were in contact with each other, and pressed at 6t at room temperature to obtain a pressed product. The release film was peeled off the pressed product to obtain a self-standing circular sheet. A metal interface layer (metal: In) with a thickness of 0.1 μm was deposited on a circular sheet by sputtering. This resulted in a circular sulfide solid electrolyte sheet.

[0058] [1.3]Battery A circular positive electrode sheet (diameter: 11.28 mm) was obtained by punching out a positive electrode sheet. A circular Li-Mg foil (diameter: 13 mm) was obtained by punching out a Li-10 mass%Mg alloy foil (thickness: 100 μm). A circular Ni foil (diameter: 14.5 mm) was obtained by punching out a roughened Ni foil to be used as a negative electrode current collector. A circular negative electrode sheet was fabricated by bonding the circular Li-Mg foil and the circular Ni foil with a thickness of 0.1 mm. A circular sulfide solid electrolyte sheet was placed between the circular positive electrode sheet and the circular negative electrode sheet to obtain a laminate. The laminate was placed inside a laminate casing. A positive electrode tab (material: aluminum) was attached to the positive electrode sheet, and a negative electrode tab (material: nickel) was attached to the negative electrode sheet, and the inside of the laminate casing was vacuum sealed. The sealed cell was isotropically pressed at 300 MPa using CIP (cold isotropic pressing) to fabricate a battery. With a cutoff voltage of 1.2V, the current is 0.584mA / cm². 2 (1C = 5.84mA / cm 2 The battery was charged at a constant current density (equivalent to 0.1C) and the initial discharge was performed at 60°C.

[0059] [2] Simulation analysis [2.1] Reference example 2 The stress on the solid electrolyte layer caused by the initial volume expansion of the positive electrode composite during the first discharge was analyzed using known stress analysis software.

[0060] As the test specimen (simulation model), a battery 100 shown in Figures 4 and 5 was used. The battery 100 has a positive electrode 110, a solid electrolyte layer 120, and a negative electrode 130. The positive electrode 110, the solid electrolyte layer 120, and the negative electrode 130 are stacked along the X-axis.

[0061] The positive electrode 110 has a plurality of positive electrode composite material portions 111 and a positive electrode current collector 112. As shown in Figure 5, the plurality of positive electrode composite material portions 111 are arranged in a pillar-like manner with a gap G111 between them. The area R between adjacent positive electrode composite material portions 111 is a void. In other words, there was no filler material in area R. The positive electrode composite material portions 111 are cylindrical in shape. The diameter D111 of the positive electrode composite material portion 111 was 268 μm. The porosity of the electrode composite material portion was 52.5%. The porosity of the electrode composite material portion represents the ratio of the total area of ​​the plurality of positive electrode composite material portions 111 within the electrode composite material portion formation region R111 (see Figure 5) to the area of ​​the electrode composite material portion formation region R111.

[0062] The negative electrode 130 comprises a negative electrode composite layer 131 and a negative electrode current collector 132.

[0063] The length H111 in the X-axis direction of the positive electrode composite material portion 111 (see Figure 4) was 78 μm. The length H120 in the X-axis direction of the solid electrolyte layer 120 (see Figure 4) was 75 μm. The length H131 in the X-axis direction of the negative electrode composite material layer 131 (see Figure 4) was 60 μm. The diameter L111 of the formation region R111 of the electrode composite material portion was 11.28 mm. The diameter L120 of the solid electrolyte layer 120 and the diameter L131 of the negative electrode composite material layer 131 were both 15.1 mm.

[0064] The material of the positive electrode composite layer 111 was sulfur. The material of the solid electrolyte layer 120 was a sulfide solid electrolyte. The material of the negative electrode composite layer 131 was a Li-Mg alloy.

[0065] The stress at the interface between the solid electrolyte layer 120 and the negative electrode composite layer 131 was analyzed when a restraining force F (pressure: 5 MPa) was applied to the battery 100 from both directions in the X-axis direction, causing the positive electrode composite layer 111 to expand in volume (30% in the X-axis direction, and 3% in the Y-axis and Z-axis directions), and the negative electrode composite layer 131 to contract in volume in the X-axis direction. At this time, the positive electrode composite layer 111 contracted by 30% in volume in the X-axis direction and expanded by 3% in volume in the Y-axis and Z-axis directions. The negative electrode composite layer 131 contracted by 50% in volume in the X-axis direction. The measurement results are shown in Table 1.

[0066] [2.2] Reference example 3~Reference example 6 The stress analysis was performed in the same manner as in Reference Example 2, except that the diameter of the positive electrode composite section 111 was changed as shown in Table 1. The material of the filler used to fill section R in Reference Example 5 was sapphire. The measurement results are shown in Table 1.

[0067] [Table 1]

[0068] The results in Table 1 show that the higher the porosity, the lower the average value of the maximum principal stress tends to be.

[0069] [2.3] Reference Examples 7 and 8 As Reference Example 7, the stress was measured in the same manner as in Reference Example 2, except that the positive electrode composite material 111 was changed from a cylindrical shape to a hexagonal prism shape. As Reference Example 8, the stress was measured in the same manner as in Reference Example 2, except that the positive electrode composite material 111 was changed from a cylindrical shape to a square prism shape. Of Reference Examples 1, 7, and 8, Reference Example 1 had the lowest average maximum principal stress, while Reference Example 8 had the highest average maximum principal stress. From these results, it was found that when the positive electrode composite material is cylindrical, the battery can suppress the occurrence of cracks in the solid electrolyte layer. [Explanation of Symbols]

[0070] 1A, 1B: battery, 10A, 10B: positive electrode, 11a: first positive electrode composite part, 11b: second positive electrode composite part, 12: positive electrode current collector, 13: reinforcing material, 20: solid electrolyte layer, 30: negative electrode, 31: negative electrode composite material layer, 32: negative electrode current collector, 40: exterior body

Claims

1. A battery comprising a positive electrode, a solid electrolyte layer, and a negative electrode in this order along a first direction, At least one of the positive electrode and the negative electrode has a plurality of cylindrical first electrode composite portions and a plurality of cylindrical second electrode composite portions, Viewed from the first direction, the plurality of first electrode composite material portions are arranged on the central part side of the battery relative to the plurality of second electrode composite material portions. Two adjacent portions of the multiple first electrode composite material portions and the multiple second electrode composite material portions are arranged with a gap between them. A battery in which the diameter of the first electrode composite portion is smaller than the diameter of the second electrode composite portion.

2. The length of the first electrode composite portion in the first direction and the length of the second electrode composite portion in the first direction are the same. The battery according to claim 1, wherein the shortest distance G between the first electrode composite portion and the second electrode composite portion adjacent to the first electrode composite portion is longer than the length of the first electrode composite portion in the first direction.

3. The battery according to claim 2, wherein the shortest interval G is longer than twice the expansion amount of the second electrode composite portion.

4. A lithium-ion battery comprising a positive electrode, a solid electrolyte layer, and a negative electrode in this order along a first direction, At least one of the positive electrode or the negative electrode has a plurality of cylindrical first electrode composite parts and a plurality of cylindrical second electrode composite parts, Multiple first electrode composite portions are arranged relative to multiple second electrode composite portions on the central side of the lithium-ion battery as viewed from the first direction. Two adjacent portions of the multiple first electrode composite material portions and the multiple second electrode composite material portions are arranged with a gap between them. The diameter of the first electrode composite portion is smaller than the diameter of the second electrode composite portion. A lithium-ion battery in which the aforementioned interval is such that when the positive electrode or the negative electrode has absorbed approximately the maximum amount of lithium, two adjacent portions of the plurality of first electrode composite material portions and the plurality of second electrode composite material portions do not come into contact with each other.

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