Battery and lithium ion battery

Abstract

Provided is a battery capable of suppressing the occurrence of cracks in a solid electrolyte layer. The battery includes a positive electrode, a solid electrolyte layer, and a negative electrode in this order in a first direction. In the battery, at least one of the positive electrode and the negative electrode has a plurality of cylindrical first electrode composite parts and a plurality of cylindrical second electrode composite parts. When viewed from the first direction, the plurality of first electrode composite material parts are disposed on the center portion side of the battery with respect to the plurality of second electrode composite material parts. Two adjacent ones of the plurality of first electrode composite material parts and the plurality of second electrode composite material parts are arranged at intervals. The diameter of the first electrode composite material part is smaller than the diameter of the second electrode composite material part.

Description

Technical Field

[0001] This invention relates to a battery and a lithium-ion battery. Background Technology

[0002] In recent years, the development of sulfur batteries using sulfur as the positive electrode active material has been progressing. Sulfur has a high theoretical capacity (i.e., 1675 mAh / g). Patent Document 1 discloses a positive electrode composite material. This positive electrode composite material contains a positive electrode active material containing sulfur (S), a sulfur-containing compound containing phosphorus (P) and sulfur (S), and a conductive additive, but substantially does not contain lithium (Li). This positive electrode composite material has specific specifications.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2019-212615 Summary of the Invention

[0004] However, in batteries comprising a positive electrode composite material layer including the positive electrode composite material disclosed in Patent Document 1 and a solid electrolyte layer, the volume change (i.e., expansion or contraction) of the positive electrode active material caused by charging or discharging the battery can easily exert stress on the solid electrolyte layer. As a result, cracks may occur in the solid electrolyte layer.

[0005] The present invention was made in view of the above circumstances.

[0006] One embodiment of the present invention aims to solve the problem of providing a battery and a lithium-ion battery capable of suppressing the generation of cracks in the solid electrolyte layer.

[0007] The means to solve the above problems include the following implementation methods.

[0008] <1> The battery of the first aspect of the present invention is the following battery:

[0009] It sequentially comprises a positive electrode, a solid electrolyte layer, and a negative electrode along the first direction, wherein,

[0010] At least one of the positive electrode and the negative electrode has multiple cylindrical first electrode composite material portions and multiple cylindrical second electrode composite material portions.

[0011] Viewed from the first direction, the plurality of first electrode composite material portions are disposed on the central portion side of the battery relative to the plurality of second electrode composite material portions.

[0012] Two adjacent first electrode composite material portions and two adjacent second electrode composite material portions are arranged with a gap between them.

[0013] The diameter of the first electrode composite material part is smaller than the diameter of the second electrode composite material part.

[0014] When viewed from the first direction, the battery reaction in the central part of the battery tends to be easier to occur than in parts not in the central part. In other words, the volume change of at least one of the positive electrode composite material part and the negative electrode composite material part (hereinafter collectively referred to as the "composite material part") in the central part of the battery tends to be greater than that in parts not in the central part. If the volume of the composite material part changes in the second direction, stress is generated in the solid electrolyte layer in the second direction.

[0015] Because the first method has the aforementioned structure, the stress in the second direction experienced by the solid electrolyte layer, which is affected by the volume change of the composite material portion, is mitigated. As a result, the battery of the first method can suppress the formation of cracks in the solid electrolyte layer. Furthermore, in the first method, by adjusting the arrangement of the multiple first electrode composite materials, the volume of pores that do not participate in the battery reaction can be reduced. As a result, the energy density of the battery can be improved.

[0016] <2> The battery of the second aspect of the present invention is the battery described in <1>, wherein,

[0017] The length of the first electrode composite material portion in the first direction is the same as the length of the second electrode composite material portion in the first direction.

[0018] The shortest interval G between the first electrode composite material portion and the second electrode composite material portion adjacent to the first electrode composite material portion is longer than the length of the first electrode composite material portion in the first direction.

[0019] To reduce the interfacial resistance of the positive electrode, solid electrolyte layer, and negative electrode, a confining pressure is typically applied to the battery along the first direction. This confining pressure can cause the composite material section to be crushed and deformed (expanded in diameter).

[0020] Because of the structure described above in the second method, even when constrained 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 method can further suppress the generation of cracks in the solid electrolyte layer.

[0021] <3> The battery of the third aspect of the present invention is the battery described in <2>, wherein,

[0022] The shortest interval G is longer than twice the length of the expansion of the second electrode composite material portion.

[0023] In this invention, the "expansion amount of the second electrode composite material part" is represented by the product of the inherent expansion rate of the constituent elements of the second electrode composite material part and the diameter of the second electrode composite material part.

[0024] Because of the structure described above in the third method, it is less likely for two adjacent composite material parts to come into physical contact. As a result, the battery of the third method can further suppress the generation of cracks in the solid electrolyte layer.

[0025] <4> The lithium-ion battery of the fourth aspect of the present invention is the following lithium-ion battery:

[0026] It sequentially comprises a positive electrode, a solid electrolyte layer, and a negative electrode along the first direction, wherein,

[0027] At least one of the positive electrode or the negative electrode has multiple cylindrical first electrode composite material portions and multiple cylindrical second electrode composite material portions.

[0028] The plurality of first electrode composite material portions are disposed relative to the plurality of second electrode composite material portions on the central portion side when viewed from the first direction of the lithium-ion battery.

[0029] Two adjacent first electrode composite material portions and two adjacent second electrode composite material portions are arranged with a gap between them.

[0030] The diameter of the first electrode composite material part is smaller than the diameter of the second electrode composite material part.

[0031] The interval is the interval between two adjacent non-contacting intervals among the plurality of first electrode composite material portions and the plurality of second electrode composite material portions when the positive electrode or the negative electrode absorbs lithium to near its maximum amount.

[0032] In this invention, "when the positive electrode absorbs nearly the maximum amount of current-carrying ions" refers to when the battery's state of charge (SOC) is 0%. "When the negative electrode absorbs nearly the maximum amount of current-carrying ions" refers to when the SOC is 100%.

[0033] Sulfur-containing positive electrode active materials have low Young's modulus. In lithium-ion batteries using sulfur-containing positive electrode active materials, the positive electrode composite material is easily crushed and deformed (easily expands in diameter) when the lithium-ion battery is constrained.

[0034] Because of the structure described above in the fourth method, even when constrained pressure is applied to the lithium-ion battery, the two adjacent composite material parts are less likely to come into physical contact. As a result, the lithium-ion battery of the fourth method can further suppress the generation of cracks in the solid electrolyte layer.

[0035] Invention Effects

[0036] According to the present invention, a battery and a lithium-ion battery capable of suppressing the generation of cracks in the solid electrolyte layer are provided. Attached Figure Description

[0037] Figure 1 This is a cross-sectional view of the battery according to the first embodiment.

[0038] Figure 2 This is a top view of the positive electrode composite material portion and the solid electrolyte layer of the battery according to the first embodiment.

[0039] Figure 3 This is a cross-sectional view of the battery according to the second embodiment.

[0040] Figure 4 This is a cross-sectional view of the battery in Example 2.

[0041] Figure 5 This is a top view of the positive electrode composite material and solid electrolyte layer of the battery in Reference Example 2. Detailed Implementation

[0042] In this invention, the numerical range represented by "~" refers to the range encompassed by taking the values ​​before and after "~" as the minimum and maximum values, respectively. In the numerical ranges recorded in stages in this invention, the upper or lower limit value recorded in a certain numerical range can be replaced by the upper or lower limit value of other numerical ranges recorded in stages. In this invention, combining two or more preferred methods is a more preferred method. In this invention, the term "process" includes not only independent processes, but also processes that can achieve their desired purpose, even if they cannot be clearly distinguished from other processes.

[0043] (1) First Embodiment

[0044] The battery 1A in the first embodiment is a lithium-ion battery with a unipolar structure. For example... Figure 1 As shown, 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 sequentially. The outer casing 40 houses the positive electrode 10A, the solid electrolyte layer 20, and the negative electrode 30. Battery 1A is a cuboid.

[0045] 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 orthogonal to the X-axis direction is defined as the Y-axis direction (an example of the second direction). The direction orthogonal to both the X-axis and Y-axis directions is defined as the Z-axis direction (an example of the second direction). Furthermore, these orientations are not limited to the orientation used in the battery of the present invention.

[0046] (1.1) Positive electrode

[0047] The positive electrode 10A has 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 disposed on a main surface S12 of the positive electrode current collector 12.

[0048] Hereinafter, the plurality of first positive electrode composite material portions 11a and the plurality of second positive electrode composite material portions 11b will also be collectively referred to as "positive electrode composite material portions".

[0049] (1.1.1) Positive electrode composite material section

[0050] like Figure 2 As shown, the positive electrode composite material is arranged in a staggered pattern at 45 degrees.

[0051] Viewed from the X-axis direction, a plurality of first positive electrode composite material portions 11a are disposed relative to a plurality of second positive electrode composite material portions 11b on the central portion side of the battery 1A (in other words, the central portion of the main surface S20 of the solid electrolyte layer 20). In other words, a plurality of first positive electrode composite material portions 11a are disposed on the central portion of the battery 1A, and a plurality of second positive electrode composite material portions 11b are disposed in a manner that surrounds the plurality of first positive electrode composite material portions 11a.

[0052] Two adjacent portions of the plurality of first positive electrode composite material portions 11a and the plurality of second positive electrode composite material portions 11b are arranged with a gap between them. In the first embodiment, the portion R (referring to the reference) between two adjacent portions of the plurality of first positive electrode composite material portions 11a and the plurality of second positive electrode composite material portions 11b is... Figure 1 () represents pores.

[0053] The length of the first positive electrode composite material part 11a in the first direction is the same as the length of the second positive electrode composite material part 11b in the first direction, which is H (reference). Figure 1 The shortest interval G between the first positive electrode composite material section 11a and the second positive electrode composite material section 11b (reference) Figure 2 The shortest interval G is longer than the length H of the first positive electrode composite material section 11a in the X-axis direction. The shortest interval G is longer than twice the expansion amount α of the second positive electrode composite material section 11b. The shortest interval Ga between adjacent first positive electrode composite material sections 11a (reference) Figure 2 The shortest interval Gb between the second positive electrode composite material section 11b and the adjacent second positive electrode composite material section 11b (reference) Figure 2 It is the same as the shortest interval G.

[0054] The shortest interval G, the shortest interval Ga, and the shortest interval Gb are the two adjacent non-contact intervals in multiple positive electrode composite parts when the lithium adsorption capacity of the positive electrode 10A reaches close to the maximum.

[0055] The first positive electrode composite material section 11a and the second positive electrode composite material section 11b are cylindrical. The diameter D11a of the first positive electrode composite material section 11a (reference) Figure 2 The diameter D11b of the second positive electrode composite material section 11b is smaller than that of the second positive electrode composite material section 11b (reference). Figure 2 The diameter D11b can be 0.10mm to 1mm or 0.10mm to 0.35mm.

[0056] The porosity of the electrode composite material is not particularly limited, but from the viewpoint of suppressing the generation of cracks in the solid electrolyte layer 20, it is preferably 40% to 90%. From the viewpoint of suppressing the generation of cracks in the solid electrolyte layer 20 and ensuring sufficient energy density of the battery, the porosity of the electrode composite material is preferably 70% to 80%. "Porosity of the electrode composite material" refers to the ratio of the total area of ​​pores in the forming region of the electrode composite material to the area of ​​the forming region of the electrode composite material when viewed from the first direction. "Forming region of the electrode composite material" refers to the region with the smallest area including the entirety of the plurality of outermost second electrode composite materials when viewed from the first direction, and is represented by a rectangular (i.e., square or rectangle), circular, or elliptical region. In the first embodiment, "forming region R11 of the electrode composite material" refers to the region with the smallest area including the entirety of the plurality of outermost second positive electrode composite materials 11b when viewed from the X-axis direction, and is represented by a rectangular region.

[0057] The positive electrode composite material contains positive electrode active materials (e.g., monomeric 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 halide solid electrolytes), conductive agents (e.g., acetylene black, metal particles, and conductive polymers), and binders (e.g., styrene-butadiene rubber and polyvinylidene fluoride).

[0058] The method for forming the positive electrode composite material is not particularly limited, and methods (a1) and (a2) are examples. In method (a1), a 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 (e.g., an ultrashort pulse laser).

[0059] (1.1.2) Positive current collector

[0060] Materials used for the positive current collector 12 include, for example, aluminum, copper, stainless steel, and nickel. The shape of the positive current collector 12 is, for example, foil or mesh.

[0061] (1.2) Solid electrolytes

[0062] The solid electrolyte layer 20 contains a solid electrolyte (e.g., sulfide solid electrolyte, oxide solid electrolyte, and halide solid electrolyte), and may further contain an adhesive (e.g., styrene-butadiene rubber and polyvinylidene fluoride, etc.) as needed.

[0063] The solid electrolyte layer 20 may have a Li-X alloy interface layer (X is Mg, Sn, Zn, or Al) at the interface with the negative electrode 30. It is known that during the charging and discharging of the 1A battery, if the solid electrolyte layer 20 comes into physical contact with metallic lithium, a reduction and decomposition reaction of the solid electrolyte layer 20 will occur. If the reduction and decomposition reaction of the solid electrolyte layer 20 occurs, a layer that constitutes an interface resistance (hereinafter also referred to as a "resistive layer") may be formed between the solid electrolyte layer 20 and the negative electrode 30. The solid electrolyte layer 20 suppresses the formation of the resistive layer by having a Li-X alloy interface layer.

[0064] (1.3) Negative electrode

[0065] The negative electrode 30 has a negative electrode composite material layer 31 and a negative electrode current collector 32. The negative electrode composite material layer 31 is disposed on a main surface S32 of the negative electrode current collector 32.

[0066] The negative electrode composite layer 31 contains negative electrode active materials (e.g., lithium metal, alloys of lithium metal and metal X (X such as Mg, Ag, In, Sn, Si, Ga, Au, and Pt), graphite, lithium titanate, and Si monomers). The negative electrode composite layer may further contain solid electrolytes (e.g., sulfide solid electrolytes, oxide solid electrolytes, and halide solid electrolytes), conductive agents (e.g., acetylene black, metal particles, and conductive polymers), and binders (e.g., styrene-butadiene rubber and polyvinylidene fluoride).

[0067] Materials used for the negative current collector 32 include, for example, aluminum, copper, stainless steel, and nickel. The shape of the negative current collector 32 may be, for example, foil or mesh.

[0068] (1.4) Exterior body

[0069] Examples of outer casing 40 include laminated films (e.g., aluminum-plastic film) and battery cans (e.g., cylindrical, square, and button-shaped).

[0070] (1.5) Effects

[0071] For reference Figure 1 and Figure 2 As described above, battery 1A includes a positive electrode 10A, a solid electrolyte layer 20, and a negative electrode 30. The positive electrode 10A has multiple cylindrical first positive electrode composite material portions 11a and multiple cylindrical second positive electrode composite material portions 11b. Viewed from the X-axis direction, the multiple first positive electrode composite material portions 11a are arranged relative to the multiple second positive electrode composite material portions 11b at the central portion side of battery 1A. Adjacent pairs of the multiple first positive electrode composite material portions 11a and the multiple second positive electrode composite material portions 11b are spaced apart. The diameter D11a of the first positive electrode composite material portion 11a is smaller than the diameter D11b of the second positive electrode composite material portion 11b.

[0072] As a result, the stresses in the Y-axis and Z-axis directions experienced by the solid electrolyte layer 20, which are accompanied by the volume change of the positive electrode composite material portion 11a, are alleviated. Consequently, the battery 1A is able to suppress the generation of cracks in the solid electrolyte layer 20.

[0073] For reference Figure 1 and Figure 2 As explained, in battery 1A, the length of the first positive electrode composite material portion 11a in the X-axis direction is the same as the length of the second positive electrode composite material portion 11b in the X-axis direction, which is length H. The shortest interval G is longer than the length H.

[0074] Therefore, even when constrained pressure is applied to the battery 1A, the two adjacent first positive electrode composite material portions 11a are unlikely to come into physical contact. That is, in the first embodiment, there are pores between the two adjacent positive electrode composite material portions. As a result, the battery 1A can further suppress the generation of cracks in the solid electrolyte layer 20.

[0075] For reference Figure 1 and Figure 2 As explained, the shortest interval G is longer than twice the length of the expansion of the second positive electrode composite material part 11b.

[0076] Therefore, it is difficult for two adjacent positive electrode composite material sections to make physical contact. As a result, battery 1A can further suppress the generation of cracks in the solid electrolyte layer 20.

[0077] For reference Figure 1 and Figure 2 As explained, the shortest interval G, the shortest interval Ga, and the shortest interval Gb are the two adjacent non-contact intervals in the multiple positive electrode composite parts when the lithium adsorption capacity of the positive electrode 10A reaches near its maximum.

[0078] Therefore, even when a constraint pressure is applied to battery 1A in the X-axis direction, the two adjacent positive electrode composite material portions are unlikely to make physical contact. As a result, battery 1A can further suppress the generation of cracks in the solid electrolyte layer 20.

[0079] (2) Second implementation method

[0080] The battery 1B of the second embodiment is the same as the battery 1A of the first embodiment, except that filler material is disposed at part R. Figure 3 As shown, battery 1B includes a positive electrode 10B, a solid electrolyte layer 20, a negative electrode 30, and an outer casing 40.

[0081] The positive electrode 10B has multiple first positive electrode composite material portions 11a (an example of a first electrode composite material portion), multiple second positive electrode composite material portions 11b (an example of a second electrode composite material portion), a positive electrode current collector 12, and a filler material 13. The filler material 13 fills the portion R between two adjacent first positive electrode composite material portions 11a and multiple second positive electrode composite material portions 11b (see reference). Figure 3 ).

[0082] The filler material 13 absorbs the elongation of the plurality of first positive electrode composite material portions 11a and the plurality of second positive electrode composite material portions 11b in the Y-axis and Z-axis directions caused by the charging or discharging of the battery 1B. As a material for the filler material 13, materials with a bending strength of 500 MPa or more (preferably 600 MPa or more) can be cited. Specifically, as a material for the filler material 13, sapphire can be cited, for example.

[0083] Methods for forming the filler material 13 include, for example, a first method and a second method. In the first method, the filler material 13, formed according to the shape of the portion R, is embedded into the portion R. In the second method, uncured filler material 13 is introduced into the portion R, and then the uncured filler material 13 is cured.

[0084] Battery 1B is identical to battery 1A except that it has filler material 13 at part R. Therefore, battery 1B performs the same function as battery 1A.

[0085] (3) Variations

[0086] In the first and second embodiments, the shortest interval G is longer than the length H of the first positive electrode composite material portion 11a in the X-axis direction, but the present invention is not limited thereto. The shortest interval G can be less than or equal to the length H.

[0087] In the first and second embodiments, the shortest interval G is longer than twice the length of the expansion amount α of the second positive electrode composite material portion 11b, but the present invention is not limited thereto. The shortest interval G can be less than twice the length of the expansion amount α of the second positive electrode composite material portion 11b.

[0088] Battery 1A and Battery 1B are lithium-ion batteries, but the present invention is not limited thereto. The batteries can be alkali metal-ion batteries (e.g., sodium-ion batteries) and alkaline earth metal batteries, etc.

[0089] Although only the positive electrode 10A and the positive electrode 10B have a plurality of first positive electrode composite material portions 11a (an example of a first electrode composite material portion) and a plurality of second positive electrode composite material portions 11b (an example of a second electrode composite material portion), the present invention is not limited thereto. The plurality of first electrode composite material portions and the plurality of second electrode composite material portions may be formed only on the negative electrode, or they may be formed on both the positive electrode and the negative electrode.

[0090] In the first and second embodiments, the positive electrode composite material portions are arranged in a 45-degree staggered pattern, but the present invention is not limited to this. The arrangement pattern of the positive electrode composite material portions can be a 60-degree staggered pattern, a parallel pattern, a columnar pattern, or an irregular pattern.

[0091] In the first and second embodiments, the electrode structure is a unipolar structure, but it can also be a bipolar structure.

[0092] The present invention will be further described in detail below through embodiments, but the invention is not limited to these embodiments.

[0093] [1] Reference Example

[0094] [1.1] Positive electrode

[0095] Sulfur (S) (vacuum-dried at 80°C), P2S5, and monolayer CNTs (vacuum-dried at 120°C) were mixed in a mortar to obtain a mixture. The mass ratio (S:P2S5:monolayer CNT) was 42:35:23. 1.7 g of the mixture and 80 g of zirconia balls (4 mm diameter) were added to each milling jar, and milling was performed using a planetary ball mill at 400 rpm for 36 hours. The milled mixture was dry-graded using a 38 μm sieve to obtain the sulfur cathode composite material.

[0096] A cathode slurry was prepared by mixing a sulfur cathode composite material, a binder, and mesitylene as a solvent. The mass ratio (sulfur cathode composite material: binder) was 99.7:0.3. The cathode slurry was coated onto a roughened aluminum foil, which serves as the cathode current collector, through a mesh of specified shape and size, with a coating gap of 220 μm. After pre-drying at 50°C, it was finally dried at 100°C for 30 minutes to obtain the cathode sheet.

[0097] [1.2] Solid electrolyte layer

[0098] 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 approximately 3 hours, followed by final drying at 165°C for 1 hour. This yielded a laminate. The laminate was punched to obtain two circular laminates (diameter: 14.5 mm). The two circular laminates were overlapped with the sulfide solid electrolyte slurry coating in contact with each other and pressed under a pressure of 6 tons at room temperature to obtain a pressed part. The release film was peeled off from the pressed part to obtain a self-standing circular sheet. A metal interface layer (metal: In) with a thickness of 0.1 μm was deposited on the circular sheet by sputtering. This yielded a circular sulfide solid electrolyte sheet.

[0099] [1.3] Battery

[0100] A circular positive electrode sheet (diameter: 11.28 mm) was obtained by punching a Li-10 wt% Mg alloy foil (thickness: 100 μm) to obtain a circular Li-Mg foil (diameter: 13 mm). A roughened Ni foil, used as the negative electrode current collector, was punched to obtain a circular Ni foil (diameter: 14.5 mm). A pressure of 0.1 tons was applied to bond the circular Li-Mg foil and the circular Ni foil together to create a circular negative electrode sheet. A circular sulfide solid electrolyte sheet was placed between the circular positive and negative electrode sheets to obtain a laminate. The laminate was then placed within a laminated 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. The laminated casing was then vacuum-sealed. The battery was fabricated by applying isostatic pressure (CIP) at 300 MPa to the sealed battery. Set the lower cutoff voltage to 1.2V, with a current of 0.584mA / cm. 2 (As 1C = 5.84mA / cm) 2The battery was charged with a constant current density of 0.1C and then discharged for the first time at 60°C.

[0101] [2] Simulation analysis

[0102] [2.1] Refer to Example 2

[0103] Using known stress analysis software, the stress on the solid electrolyte layer caused by the initial volume expansion of the positive electrode composite material during the first discharge was analyzed.

[0104] As an experimental subject (simulation model), it was used Figure 4 and Figure 5 The battery 100 shown 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 direction.

[0105] The positive electrode 110 has multiple positive electrode composite material portions 111 and positive electrode current collectors 112. For example... Figure 5 As shown, multiple positive electrode composite material sections 111 are arranged in a columnar shape with intervals G111. The portion R between adjacent positive electrode composite material sections 111 is a pore. That is, no filler material is present in portion R. The positive electrode composite material section 111 is cylindrical. The diameter D111 of the positive electrode composite material section 111 is 268 μm. The porosity of the electrode composite material section is 52.5%. The porosity of the electrode composite material section represents the total area of ​​pores within the formation region R111 of the electrode composite material section relative to the formation region R111 (reference). Figure 5 The proportion of the area of ​​).

[0106] The negative electrode 130 has a negative electrode composite material layer 131 and a negative electrode current collector 132.

[0107] The length H111 of the positive electrode composite material part 111 in the X-axis direction (reference) Figure 4 The thickness is 78 μm. The length H120 of the solid electrolyte layer 120 in the X-axis direction (reference) is 78 μm. Figure 4 The length H131 of the negative electrode composite layer 131 in the X-axis direction is 75 μm. Figure 4 The diameter of the electrode composite material layer R111 is 60 μm. The diameter of the electrode composite material layer R111 is 11.28 mm. The diameters of the solid electrolyte layer 120 (L120) and the negative electrode composite material layer 131 (L131) are 15.1 mm.

[0108] The positive electrode composite material 111 is made of sulfur. The solid electrolyte layer 120 is made of sulfide solid electrolyte. The negative electrode composite material layer 131 is made of Li-Mg alloy.

[0109] A constraint force F (pressure: 5 MPa) from both sides in the X-axis direction was applied to the battery 100. The stress at the interface between the solid electrolyte layer 120 and the negative electrode composite layer 131 was analyzed when the positive electrode composite material portion 111 expanded in volume (30% in the X-axis direction and 3% in the Y-axis and Z-axis directions) and the negative electrode composite material layer 131 contracted in volume in the X-axis direction. At this time, the positive electrode composite material portion 111 contracted in volume by 30% in the X-axis direction and expanded in volume by 3% in the Y-axis and Z-axis directions. The negative electrode composite material layer 131 contracted in volume by 50% in the X-axis direction. The measurement results are shown in Table 1.

[0110] [2.2] Refer to Examples 3 to 6

[0111] The diameter of the positive electrode composite material section 111 was changed as shown in Table 1. Otherwise, the stress was analyzed in the same manner as in Reference Example 2. The filler material for the filling portion R in Reference Example 5 was sapphire. The measurement results are shown in Table 1.

[0112]

[0113] The results in Table 1 show the following trend: the higher the porosity, the lower the average value of the maximum principal stress.

[0114] [2.3] Refer to Example 7 and Example 8

[0115] As Reference Example 7, the positive electrode composite material part 111 was changed from a cylindrical shape to a hexagonal prism shape, and the stress was measured in the same manner as in Reference Example 2. As Reference Example 8, the positive electrode composite material part 111 was changed from a cylindrical shape to a square prism shape, and the stress was measured in the same manner as in Reference Example 2.

[0116] Among Reference Examples 1, 7, and 8, Reference Example 1 has the lowest average value of the maximum principal stress, while Reference Example 8 has the highest average value of the maximum principal stress. This result indicates that if the positive electrode composite material is cylindrical, the battery can suppress the formation of cracks in the solid electrolyte layer.

[0117] Symbol Explanation

[0118] 1A, 1B - Battery; 10A, 10B - Positive electrode; 11a - First positive electrode composite material section; 11b - Second positive electrode composite material section; 12 - Positive electrode current collector; 13 - Filler material; 20 - Solid electrolyte layer; 30 - Negative electrode; 31 - Negative electrode composite material layer; 32 - Negative electrode current collector; 40 - Outer casing.

Claims

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

2. The battery according to claim 1, characterized in that, The length of the first electrode composite material portion in the first direction is the same as the length of the second electrode composite material portion in the first direction. The shortest interval G between the first electrode composite material portion and the second electrode composite material portion adjacent to the first electrode composite material portion is longer than the length of the first electrode composite material portion in the first direction.

3. The battery according to claim 2, characterized in that, The shortest interval G is longer than twice the length of the expansion of the second electrode composite material portion.

4. A lithium-ion battery, comprising a positive electrode, a solid electrolyte layer, and a negative electrode sequentially along a first direction, characterized in that... At least one of the positive electrode or the negative electrode has multiple cylindrical first electrode composite material portions and multiple cylindrical second electrode composite material portions. The plurality of first electrode composite material portions are disposed relative to the plurality of second electrode composite material portions on the central portion side when viewed from the first direction of the lithium-ion battery. Two adjacent first electrode composite material portions and two adjacent second electrode composite material portions are arranged with a gap between them. The diameter of the first electrode composite material part is smaller than the diameter of the second electrode composite material part. The interval is the interval between two adjacent non-contacting intervals among the plurality of first electrode composite material portions and the plurality of second electrode composite material portions when the positive electrode or the negative electrode absorbs lithium to near its maximum amount.

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