Solid-state battery and method for manufacturing solid-state battery

Abstract

To provide a high-quality solid battery.SOLUTION: The solid-state battery 1 includes a power generation element 14 and an insulating cover layer 15 covering the power generation element 14. The power generation unit 14 includes the electrodes 11 and 12 and the electrolytic layer 13 which face each other at the D1 in the first direction. The cover layer 15 covers an end surface D1 of the internal electrode layer 11, an end surface D2 of the internal electrode layer 12, and an end surface 11a of the electrolytic layer 13, which face a second direction 12a orthogonal to the first direction 13a, and has an electrode-lead-out surface D1 and D2 which face a third direction D3 orthogonal to the first direction 11b and the second direction and from which the end surface and of the internal electrode layers 11 and 12 are exposed outside. 12b 10a 10b. External connection terminals 20 and 30 are provided on the electrode-leading surfaces 10a and 10b, respectively. For example, the power generation elements 14 have, in at least a part thereof, a configuration in which the distances Lx from the outer surface D2 facing the second direction 15a of the cover layer 15 to the end surfaces 11a, 12a, and 13a are different from each other.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a solid-state battery and a method for manufacturing a solid-state battery. [Background technology]

[0002] With regard to all-solid-state batteries having a unit cell structure consisting of a set of sintered positive and negative electrode layers stacked with a solid electrolyte layer sandwiched therebetween, there are known techniques for forming a step portion in which the end faces of the positive and negative electrode layers are misaligned with each other, and a technique for making the end face of the solid electrolyte layer at the step portion protrude outward (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-69775 Summary of the Invention [Problem to be solved by the invention]

[0004] A solid-state battery having a structure in which predetermined portions of a power generating element including an electrode layer and an electrolyte layer are covered with an insulating cover layer is known. In such a solid-state battery, depending on the configuration of the power generating element and the cover layer, it may not be possible to obtain a high-quality solid-state battery.

[0005] In one aspect, the present invention aims to realize a high-quality solid-state battery. [Means for solving the problem]

[0006] In one aspect, there is provided a solid-state battery including: a power generating element including a first electrode layer, a second electrode layer, and an electrolyte layer facing each other in a first direction; an insulating cover layer covering a first end face of the first electrode layer facing a second direction perpendicular to the first direction, a second end face of the second electrode layer facing the second direction, and a third end face of the electrolyte layer facing the second direction, and having an electrode lead-out surface at which a fourth end face of the first electrode layer or the second electrode layer facing a third direction perpendicular to the first and second directions is exposed; and an external connection terminal provided on the electrode lead-out surface and connected to the fourth end face, wherein a first distance from an outer surface of the cover layer facing the second direction to the first end face, a second distance from the outer surface to the second end face, and a third distance from the outer surface to the third end face are different from one another.

[0007] In another aspect, a method for manufacturing such a solid-state battery is provided. [Effects of the Invention]

[0008] On the one hand, it will be possible to achieve high-quality solid-state batteries. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating an example of a solid-state battery. [Figure 2] 1A and 1B are diagrams illustrating an example of the configuration of a solid-state battery. [Figure 3] 1A to 1C are diagrams illustrating an example of a method for manufacturing a solid-state battery. [Figure 4] FIG. 4 is a diagram illustrating the distance from the outer surface of the cover layer to the layer of the power generating element. [Figure 5] 1A and 1B are diagrams illustrating solid-state batteries according to examples and comparative examples. [Figure 6] FIG. 10 is a diagram showing the relationship between the maximum distance LMax, the minimum distance LMin, and the difference LDiff therebetween for a solid-state battery. DETAILED DESCRIPTION OF THE INVENTION

[0010] Fig. 1 is a diagram illustrating an example of a solid-state battery, which is a schematic perspective view of the exterior of a main part of the example of the solid-state battery. The solid-state battery 1 shown in FIG. 1 is an example of a lithium-ion battery. The solid-state battery 1 includes a battery body 10, an external connection terminal 20, and an external connection terminal 30. The battery body 10 includes a power generating element having a positive electrode layer and a negative electrode layer, which are electrode layers, and an electrolyte layer disposed therebetween. The configuration of the power generating element disposed inside the battery body 10 will be described later. The external connection terminal 20 and the external connection terminal 30 are disposed on one end surface and the other end surface opposite to the one end surface of the battery body 10, respectively. One external connection terminal 20 is connected to one of the positive electrode layer and the negative electrode layer of the power generating element disposed inside the battery body 10, and the other external connection terminal 30 is connected to the other of the positive electrode layer and the negative electrode layer of the power generating element disposed inside the battery body 10. Of the external connection terminal 20 and the external connection terminal 30, the one connected to the positive electrode layer of the power generating element functions as the positive electrode terminal of the solid-state battery 1, and the one connected to the negative electrode layer of the power generating element functions as the negative electrode terminal of the solid-state battery 1.

[0011] 2A and 2B are diagrams illustrating an example of the configuration of a solid-state battery. 2A and 2B each show a cross-sectional view of a main part of an example of a solid-state battery. 2A is a cross-sectional view taken along line L1 in FIG. 1. 2B is a cross-sectional view taken along line L2 in FIG. 1.

[0012] As shown in FIGS. 2(A) and 2(B), the battery body 10 of the solid-state battery 1 includes a power generating element 14 in which electrode layers 11 and 12 of opposite polarities are stacked in a first direction D1 with an electrolyte layer 13 interposed therebetween, and an insulating cover layer 15 that covers a predetermined portion of the power generating element 14. For example, multiple electrode layers 11 and multiple electrode layers 12 are alternately stacked in the first direction D1 with an electrolyte layer 13 interposed therebetween. The top and bottom layers of the power generating element 14 may be the electrode layers 11 and 12, or, as shown in FIGS. 2(A) and 2(B), may be the electrolyte layers 13. One of the electrode layers 11 and 12 is a positive electrode layer and the other is a negative electrode layer. That is, the electrode layer 11 is a positive electrode layer and the electrode layer 12 is a negative electrode layer, or the electrode layer 11 is a negative electrode layer and the electrode layer 12 is a positive electrode layer.

[0013] In the power generating element 14, the electrode layer 11, the electrode layer 12, and the electrolyte layer 13 are arranged to face each other in the first direction D1, as shown in FIGS. 2(A) and 2(B). When viewed in cross section along a third direction D3 perpendicular to the first direction D1 (and the second direction D2) as shown in Figure 2(A), the power generating element 14 is arranged so that the end face 11b of the electrode layer 11 of one polarity is exposed at one end face of the battery body 10, and the end face 12b of the electrode layer 12 of the other polarity is exposed at the other end face of the battery body 10.

[0014] 2(B), in a cross-sectional view of the power generating element 14 taken along a second direction D2 perpendicular to the first direction D1 (and the third direction D3), the end faces 11a, 12a, and 13a of at least some of the electrode layers 11, 12, and electrolyte layers 13 facing the second direction D2 are arranged with a misalignment in the second direction D2. In other words, in a cross-sectional view of the power generating element 14 taken along the second direction D2, the end faces 11a, 12a, and 13a of at least some of the electrode layers 11, 12, and electrolyte layers 13 facing the second direction D2 are arranged so as not to be on the same plane along the first direction D1 and not to be aligned in the second direction D2.

[0015] The arrangement of the electrode layer 11, the electrode layer 12, and the electrolyte layer 13 of the power generating element 14 will be described in detail later. 2(A) and 2(B), the cover layer 15 covers the upper and lower surfaces (top and bottom surfaces) of the power generating element 14 that face both sides in the first direction D1. As shown in FIG. 2(B), the cover layer 15 further covers the lateral surfaces (side surfaces) of the power generating element 14 that face both sides in the second direction D2, i.e., the end surface 11a of the electrode layer 11, the end surface 12a of the electrode layer 12, and the end surface 13a of the electrolyte layer 13 that face the second direction D2.

[0016] As shown in FIG. 2A, the cover layer 15 has an electrode lead-out surface 10a facing one side of the power-generating element 14 in a third direction D3 that is perpendicular to the first direction D1 and the second direction D2, and an electrode lead-out surface 10b facing the other side of the third direction D3. An end face 11b of the electrode layer 11 facing the third direction D3 is exposed on the electrode lead-out surface 10a, and an end face 12b of the electrode layer 12 facing the third direction D3 is exposed on the electrode lead-out surface 10b. As shown in FIG. 2A, on the electrode lead-out surface 10a side, the end face 12c of the electrode layer 12 facing the third direction D3 is not exposed from the cover layer 15 but is covered by the cover layer 15. As shown in FIG. 2A, on the electrode lead-out surface 10b side, the end face 11c of the electrode layer 11 facing the third direction D3 is not exposed from the cover layer 15 but is covered by the cover layer 15.

[0017] The insulating cover layer 15 is also referred to as an “insulating layer.” A portion of the cover layer 15 adjacent to the end face 13a ( FIG. 2(B) ) of the electrolyte layer 13 facing the second direction D2, a portion adjacent to the end face 11a ( FIG. 2(B) ) of the electrode layer 11 facing the second direction D2 and the end face 11c ( FIG. 2(A) ) facing the third direction D3, and a portion adjacent to the end face 12a ( FIG. 2(B) ) of the electrode layer 12 facing the second direction D2 and the end face 12c ( FIG. 2(A) ) facing the third direction D3 are also referred to as an “embedded layer.”

[0018] The battery body 10 of the solid-state battery 1 includes the power generation element 14 and the cover layer 15 as described above. As shown in Fig. 2(A), an external connection terminal 20 and an external connection terminal 30 are provided on the end faces of the battery body 10 facing both sides in the third direction D3, respectively. That is, the external connection terminal 20 and the external connection terminal 30 are provided on the electrode lead-out surfaces 10a and 10b of the cover layer 15 of the battery body 10, respectively. One external connection terminal 20 is connected to the end face 11b of the electrode layer 11 exposed on the electrode lead-out surface 10a of the power generation element 14. The other external connection terminal 30 is connected to the end face 12b of the electrode layer 12 exposed on the electrode lead-out surface 10b of the power generation element 14.

[0019] Here, the power generation element 14, the cover layer 15, the external connection terminal 20, and the external connection terminal 30 of the solid-state battery 1 having the above configuration will be further described. The electrolyte layer 13 of the power generation element 14 contains a solid electrolyte. For example, an oxide solid electrolyte is used as the solid electrolyte of the electrolyte layer 13. As the oxide solid electrolyte of the electrolyte layer 13, for example, LAGP, which is one type of NASICON (Na super ionic conductor) type (also referred to as "NASICON type") oxide solid electrolyte, is used. LAGP is an oxide solid electrolyte represented by the general formula Li 1+x Al x Ge 2-x (PO4)3 (0 < x ≤ 1). In addition, a sulfide solid electrolyte such as Li2S (lithium sulfide)-P2S5 (diphosphorus pentasulfide) may be used as the solid electrolyte of the electrolyte layer 13.

[0020] The positive electrode layer (electrode layer 11 or 12) of the power generating element 14 includes a positive electrode active material, a conductive additive, and a solid electrolyte. The solid electrolyte of the positive electrode layer is an oxide solid electrolyte or a sulfide solid electrolyte, for example, the same type of material as the solid electrolyte used in the electrolyte layer 13. The positive electrode active material of the positive electrode layer is, for example, Li2CoP2O7 (lithium cobalt pyrophosphate, also known as "LCPO") or the like. The conductive additive of the positive electrode layer is, for example, a carbon material such as carbon fiber, carbon black, graphite, graphene, or carbon nanotubes, or a conductive material such as iron silicide. The positive electrode layer is connected to either the external connection terminal 20 or the external connection terminal 30 (the terminal different from the one to which the negative electrode layer is connected).

[0021] The negative electrode layer (electrode layer 12 or electrode layer 11) of the power generating element 14 contains a negative electrode active material, a conductive additive, and a solid electrolyte. The solid electrolyte of the negative electrode layer is an oxide solid electrolyte or a sulfide solid electrolyte, for example, the same type of material as the solid electrolyte used in the electrolyte layer 13. The negative electrode active material of the negative electrode layer is, for example, TiO2 (titanium oxide), Nb2O5 (niobium pentoxide), or the like. Other negative electrode active materials of the negative electrode layer include Li3V2(PO4)3 (lithium vanadium phosphate), Li4Ti5O 12 (lithium titanate) or the like may be used. The conductive additive for the negative electrode layer may be, for example, a carbon material such as carbon fiber, carbon black, graphite, graphene, or carbon nanotubes, or a conductive material such as iron silicide. The negative electrode layer is connected to either the external connection terminal 20 or the external connection terminal 30 (the terminal different from the one to which the positive electrode layer is connected).

[0022] In the solid-state battery 1, during charging, lithium ions are conducted and taken up from the electrode layer 11 or 12 functioning as a positive electrode layer to the electrode layer 12 or 11 functioning as a negative electrode layer via the electrolyte layer 13. During discharging, lithium ions are conducted and taken up from the electrode layer 12 or 11 functioning as a negative electrode layer via the electrolyte layer 13 to the electrode layer 11 or 12 functioning as a positive electrode layer. In the solid-state battery 1, charge and discharge operations are realized by such lithium ion conduction.

[0023] The cover layer 15 is made of various insulating materials. The insulating properties of the insulating material used for the cover layer 15 refer to the property of having no or sufficiently low influence on lithium ion conduction and electron conduction in the power generating element 14. For example, the cover layer 15 is made of an insulating material having lower electron conductivity than the electrode layers 11 and 12. The cover layer 15 is preferably made of a material that has low moisture and gas permeability and good sealing properties. In particular, it is preferable to use a material for the cover layer 15 that has a linear expansion coefficient similar to that of each layer constituting the power generating element 14 or that has good adhesion to each layer. Examples of insulating materials that can be used for the cover layer 15 include glass, ceramics, and solid electrolytes.

[0024] An external connection terminal 20 and an external connection terminal 30 are provided on the electrode lead-out surface 10a and the electrode lead-out surface 10b of the cover layer 15, respectively. The external connection terminal 20 is connected to the end surface 11b of the electrode layer 11 exposed from the cover layer 15 at the electrode lead-out surface 10a. The external connection terminal 30 is connected to the end surface 12b of the electrode layer 12 exposed from the cover layer 15 at the electrode lead-out surface 10b.

[0025] The external connection terminals 20 and 30 are formed by applying a paste containing a conductive component, such as a metal material such as Ag (silver), Cu (copper), or Ni (nickel), or a carbon material such as carbon fiber or carbon particles, to the electrode lead-out surfaces 10a and 10b, respectively, and then performing a heat treatment such as drying, curing, or baking. The external connection terminals 20 and 30 may also be formed by further depositing various metal materials, such as Ni or Sn (tin), by sputtering or plating on the electrode lead-out surfaces 10a and 10b, or on the surface of the layer formed by applying the paste and performing the heat treatment.

[0026] In the solid-state battery 1, the power generating element 14 is arranged such that, in a cross-sectional view taken along the second direction D2 as shown in Fig. 2(B), the end faces 11a, 12a, and 13a of at least some of the electrode layers 11, 12, and electrolyte layers 13 facing the second direction D2 are misaligned with each other in the second direction D2. As shown in Fig. 2(B), when the outer surface 15a (side surface) of the cover layer 15 facing the second direction D2 is defined as a reference position S0 and the distance from the reference position S0 is defined as Lx, the solid-state battery 1 can also be said to include a power generating element 14 including at least one electrode layer 11, one electrode layer 12, and one electrolyte layer 13, each of which has a different distance Lx to the end face 11a, the end face 12a, and the end face 13a facing the second direction D2.

[0027] As an example, when the widths of the electrode layers 11 and 12 in the second direction D2 are made different (e.g., smaller) from the width of the electrolyte layer 13 in the second direction D2, the end faces 11a and 12a of the electrode layers 11 and 12 are misaligned in the second direction D2 from the end face 13a of the electrolyte layer 13. Furthermore, when one electrode layer 12 is shifted in the second direction D2 relative to the other electrode layer 11, the end faces 11a and 12a of the electrode layers 11 and 12 are misaligned in the second direction D2. When multiple electrode layers 12 are included, the electrode layers 12 that are shifted in the second direction D2 are misaligned in the second direction D2 relative to the electrode layers 12 that are not shifted in the second direction D2. The same holds true when one electrode layer 11 is shifted in the second direction D2 relative to the other electrode layer 12.

[0028] As described above, the solid-state battery 1 includes a power generating element 14 including at least one electrode layer 11, one electrode layer 12, and one electrolyte layer 13, each of which has a different distance Lx from the outer surface 15a of the cover layer 15 to the end surface 11a, the end surface 12a, and the end surface 13a facing the second direction D2. In this case, the solid-state battery 1 may include the electrode layer 11, the electrode layer 12, and the electrolyte layer 13, each of which has a different polarity, as the layers of the power generating element 14 having a different distance Lx from the outer surface 15a of the cover layer 15. Alternatively, the solid-state battery 1 may include electrode layers 11 and 12 having the same polarity and an electrolyte layer 13, or electrode layers 12 and an electrolyte layer 13 having the same polarity, as the layers of the power generating element 14 having a different distance Lx from the outer surface 15a of the cover layer 15.

[0029] In the solid-state battery 1, as the power generation element 14, the end faces 11a, 12a, and 13a of at least some of the electrode layers 11, 12, and electrolyte layers 13, which face the second direction D2, are arranged with a deviation from each other in the second direction D2, thereby realizing a high-quality solid-state battery 1 in which the occurrence of cracks and the resulting deterioration in quality are suppressed, as will be described later.

[0030] One of the electrode layers 11 and 12 included in the power generating element 14 is also referred to as the "first electrode layer," its end face (end face 11a or end face 12a) facing the second direction D2 is also referred to as the "first end face," and the distance Lx from the outer surface 15a of the end face is also referred to as the "first distance." For example, the one electrode layer is the electrode layer 11 and the electrode layer 12 (opposite polarity electrode layers) in the power generating element 14 whose distance Lx is the maximum distance L Max or the electrode layer 11 or the electrode layer 12 (same polarity electrode layer) in the power generating element 14, in which the distance Lx is the maximum distance L Max The electrode layer may be such that:

[0031] Furthermore, among the electrode layers 11 and 12 included in the power generating element 14, the other electrode layer different from the one electrode layer is also referred to as the "second electrode layer," the end face (end face 11a or end face 12a) facing the second direction D2 is also referred to as the "second end face," and the distance Lx from the outer surface 15a of the end face is also referred to as the "second distance." For example, the other electrode layer is the electrode layer whose distance Lx is the smallest distance L among the electrode layers 11 and 12 (opposite polarity electrode layers) in the power generating element 14. Min or the electrode layer 11 or the electrode layer 12 (same polarity electrode layer) in the power generating element 14, the distance Lx is the smallest distance L Min The electrode layer may be such that:

[0032] In addition, among the electrolyte layers 13 included in the power generating element 14, the end face 13a of one electrolyte layer 13 facing the second direction D2 is also referred to as the "third end face," and the distance Lx from the outer surface 15a of that end face 13a is also referred to as the "third distance."

[0033] The solid state battery 1 having the above configuration is manufactured, for example, by the following method. The manufacturing method of the solid-state battery 1 broadly includes a step of forming a laminate to obtain the battery body 10, a step of cutting and firing the laminate to obtain the battery body 10, and a step of forming the external connection terminals 20 and 30.

[0034] 3A and 3B are diagrams illustrating an example of a method for manufacturing a solid-state battery. Fig. 3A shows a cross-sectional view of a main part of an example of a step of forming a laminate. Fig. 3B shows a cross-sectional view of a main part of an example of a step of cutting and firing the laminate.

[0035] <Formation of laminate> First, a laminate 40 as shown in FIG. 3(A) is formed. In forming the laminate 40, pastes for forming the electrode layer 11, the electrode layer 12, the electrolyte layer 13, and the cover layer 15 of the solid-state battery 1 are prepared in advance. One of the electrode layer 11 and the electrode layer 12 is a positive electrode layer, and the other is a negative electrode layer. Here, the paste for forming the positive electrode layer is also referred to as "positive electrode paste," and the paste for forming the negative electrode layer is also referred to as "negative electrode paste." The paste for forming the electrolyte layer 13 is also referred to as "electrolyte paste." The paste for forming the cover layer 15 is also referred to as "cover paste."

[0036] [Preparation of positive electrode paste] For example, LCPO powder as a positive electrode active material and Li as a solid electrolyte 1.5 Al 0.5 Ge 1.5 A mixture of 100 parts by weight of (PO4)3 powder (also known as "LAGP powder") and conductive additive vapor-grown carbon fiber (VGCF (VGCF-H) (VGCF; registered trademark)) powder is used, along with a total of 200 parts by weight of polyvinyl butyral binder, triethylene glycol bis(2-ethylhexanoate) plasticizer, a specified dispersant, and terpineol diluent. After mixing these materials in a ball mill for 24 to 72 hours, they are mixed and dispersed in a triple-roll mill and dispersed using a particle gauge until the material aggregates are 1 μm or less, yielding a positive electrode paste. The positive electrode paste is used to form the positive electrode layer (electrode layer 11 or 12) or the positive electrode mixture layer that forms the positive electrode layer.

[0037] [Preparation of negative electrode paste] For example, a negative electrode paste is prepared in the same manner as the positive electrode paste, except that the same amount of TiO2 is used as the negative electrode active material instead of the positive electrode active material. The negative electrode paste is used to form a negative electrode layer (electrode layer 12 or electrode layer 11) or a negative electrode mixture layer for forming a negative electrode layer.

[0038] [Preparation of Electrolyte Paste] For example, an electrolyte paste is prepared in the same manner as the positive electrode paste, except that 100 parts by mass of LAGP powder of the solid electrolyte is used instead of 100 parts by mass of the mixture of the positive electrode active material, the solid electrolyte, and the conductive additive. The electrolyte paste is used to form the electrolyte layer 13 or to form an electrolyte mixture layer for forming the electrolyte layer.

[0039] [Preparation of cover paste] For example, a cover paste can be prepared in the same manner as the electrolyte paste, except that a powder of glass or ceramic, or both, is used as the insulating material instead of the LAGP powder in the electrolyte paste. The cover paste can be used to form the cover layer 15 or a cover mixture layer for forming the cover layer.

[0040] Glasses used for cover pastes include those containing Sn, B (boron), Al (aluminum), Ba (barium), Zn (zinc), Si (silicon), Bi (bismuth), P (phosphorus), Na (sodium), Ca (calcium), F (fluorine), V (vanadium), Zr (zirconium), etc. Examples of glass used for cover pastes include SnO-B2O3-P2O5-Al2O3, SiO2-B2O3-BaO-ZnO, SiO2-B2O3-Bi2O3-ZnO, ZnO-Bi2O3-B2O3, SiO2-Bi2O3, B2O3-P2O5-Na2O-CaO-BaO-Al2O3, SnO-P2O5, SnO-B2O3-P2O5, SiO2-SnO-P2O5, Examples include SiO2-B2O3-R2O, SiO2-B2O3-ZnO-Na2O-NaF-V2O5, SnO-ZnO-P2O5-R2O-R2O, SiO2-B2O3-ZnO, SiO2-B2O3-Al2O3-ZrO2, SiO2-B2O3-ZnO-R2O-R2O, SiO2-B2O3-Al2O3-R2O-R2O (R is an alkali metal, R is an alkaline earth metal), etc.

[0041] Examples of ceramics used in the cover paste include alumina, ferrite, zirconia, zircon, barium zirconate, calcium zirconate, titanium oxide, barium titanate, strontium titanate, calcium titanate, magnesium titanate, zinc titanate, lanthanum titanate, neodymium titanate, lead zirconate, alumina nitride, silicon nitride, boron nitride, boron carbide, barium stannate, calcium stannate, magnesium silicate, mullite, steatite, cordierite, and forsterite.

[0042] In addition, a solid electrolyte may be used in the cover paste instead of or in addition to glass or ceramics. [Preparation of Laminate] A cover paste pattern is printed on a portion of a polyethylene terephthalate (PET) film using a screen printing method, and then dried, for example, at 90°C for 10 minutes. The printing and drying of the cover paste may be repeated multiple times until a predetermined thickness is achieved. This produces a cover mixture layer part in which a cover mixture layer formed from the cover paste is provided on the PET film.

[0043] A pattern of electrolyte paste is printed on a portion of another PET film using a screen printing method, and then dried, for example, at 90°C for 10 minutes. Next, a pattern of cover paste is printed on the outside of the pattern-printed electrolyte paste using a screen printing method, and then dried, for example, at 90°C for 10 minutes. The printing and drying of the electrolyte paste and the printing and drying of the cover paste may be repeated multiple times until a predetermined thickness is achieved. This produces an electrolyte mixture layer part on the PET film, in which an electrolyte mixture layer formed from the electrolyte paste and a cover mixture layer formed from the cover paste on the outside of the electrolyte mixture layer are provided.

[0044] A positive electrode paste is pattern-printed on the electrolyte mixture layer of the electrolyte mixture layer part by screen printing, and then dried, for example, at 90°C for 10 minutes. Next, a cover paste is pattern-printed on the outside of the pattern-printed positive electrode paste by screen printing, and then dried, for example, at 90°C for 10 minutes. The printing and drying of the positive electrode paste and the printing and drying of the cover paste may be repeated multiple times until a predetermined thickness is achieved. This produces a positive electrode mixture layer part, in which a positive electrode mixture layer formed from the positive electrode paste and a cover mixture layer formed from the cover paste are provided on the electrolyte mixture layer part.

[0045] The negative electrode mixture layer part is fabricated in the same manner as the fabrication of the positive electrode mixture layer part, except that a negative electrode paste is used instead of the positive electrode paste. That is, the negative electrode mixture layer part is fabricated by providing a negative electrode mixture layer formed from the negative electrode paste and an outer cover mixture layer formed from the cover paste on the electrolyte mixture layer part.

[0046] The cover mixture layer part, electrolyte mixture layer part, positive electrode mixture layer part, and negative electrode mixture layer part are also referred to simply as "parts." The cover mixture layer, electrolyte mixture layer, positive electrode mixture layer, and negative electrode mixture layer included in these parts are also referred to simply as "mixture layers."

[0047] After the above-mentioned parts are produced, for example, the electrolyte mixture layer of the electrolyte mixture layer part and its outer cover mixture layer are transferred onto the cover mixture layer of the cover mixture layer part by thermocompression bonding. The positive electrode mixture layer (or negative electrode mixture layer) and its outer cover mixture layer of the positive electrode mixture layer part (or negative electrode mixture layer part) are transferred onto the cover mixture layer by thermocompression bonding. Then, the negative electrode mixture layer (or positive electrode mixture layer) and its outer cover mixture layer of the negative electrode mixture layer part (or positive electrode mixture layer part) are transferred onto the electrolyte mixture layer and its outer cover mixture layer provided on the opposite side of the positive electrode mixture layer (or negative electrode mixture layer) and cover mixture layer by thermocompression bonding. This transfer of the positive electrode mixture layer part and the negative electrode mixture layer part is repeated until a predetermined number of layers are stacked. Thereafter, the cover mixture layer of the cover mixture layer part is similarly stacked and transferred by thermocompression bonding. The conditions for the thermocompression bonding are, for example, a pressure in the range of 2 MPa to 150 MPa and a temperature in the range of 40°C to 80°C.

[0048] During the above transfer, the electrolyte mixture layer part, the positive electrode mixture layer part, and the negative electrode mixture layer part are stacked so that the electrolyte mixture layer formed from the electrolyte paste of each part, the positive electrode mixture layer formed from the positive electrode paste, and the negative electrode mixture layer formed from the negative electrode paste have regions where they face each other, and the cover mixture layers formed from the cover paste of each part have regions where they face each other.

[0049] Using such a method, a laminate 40 having a structure as exemplified in FIG. 3(A) in cross section is produced, that is, a laminate 40 having a configuration in which an electrolyte mixture layer 43, an electrode mixture layer 41 (positive electrode mixture layer or negative electrode mixture layer), and an electrode mixture layer 42 (negative electrode mixture layer or positive electrode mixture layer) are arranged to face each other in the first direction D1 and to be offset in the second direction D2, and the outsides of these layers are each covered with a cover mixture layer 45.

[0050] For example, by adjusting the printing area of ​​the positive electrode paste and the cover paste of the positive electrode mixture layer part, the printing area of ​​the negative electrode paste and the cover paste of the negative electrode mixture layer part, and the printing area of ​​the electrolyte paste and the cover paste of the electrolyte mixture layer part, the misalignment in the second direction D2 of the electrode mixture layer 41, the electrode mixture layer 42, and the electrolyte mixture layer 43 in the laminate 40 is adjusted. Alternatively, by adjusting the stacking positions of the positive electrode mixture layer part, the negative electrode mixture layer part, and the electrolyte mixture layer part during transfer, the misalignment in the second direction D2 of the electrode mixture layer 41, the electrode mixture layer 42, and the electrolyte mixture layer 43 in the laminate 40 is adjusted.

[0051] The positive electrode mixture layer part is also referred to as a "first part" or a "second part." With regard to the positive electrode mixture layer part, the positive electrode paste used to form the positive electrode mixture layer part is also referred to as a "first electrode paste" or a "second electrode paste," the positive electrode mixture layer formed from the positive electrode paste is also referred to as a "first electrode mixture layer" or a "second electrode mixture layer," and the cover mixture layer formed from the outer cover paste is also referred to as a "first cover mixture layer" or a "second cover mixture layer."

[0052] The negative electrode mixture layer part is also referred to as a "first part" or a "second part." With regard to the negative electrode mixture layer part, the negative electrode paste used to form it is also referred to as a "first electrode paste" or a "second electrode paste," the negative electrode mixture layer formed from the negative electrode paste is also referred to as a "first electrode mixture layer" or a "second electrode mixture layer," and the cover mixture layer formed from the outer cover paste is also referred to as a "first cover mixture layer" or a "second cover mixture layer."

[0053] The electrolyte mixture layer part is also referred to as a “third part.” With regard to the electrolyte mixture layer part, the cover mixture layer formed from the cover paste on the outer side of the electrolyte mixture layer formed from the electrolyte paste is also referred to as a “third cover mixture layer.”

[0054] <Cutting and firing of laminate> The laminate 40 (FIG. 3(A)) obtained as described above is cut to have predetermined planar dimensions, for example, 4.5 mm×3.2 mm.

[0055] The laminate 40 is cut at cutting positions C1 and C2 corresponding to the regions where the cover mixture layers 45 of the stacked positive electrode mixture layer part, negative electrode mixture layer part, and electrolyte mixture layer part face each other, as shown in Fig. 3(A). This results in a cut laminate 40 having a cross-sectional structure as shown in Fig. 3(B). Cut surfaces 40a of the laminate 40 shown in Fig. 3(B) at the cutting positions C1 and C2 become outer surfaces 15a (side surfaces) of the cover layer 15 described below.

[0056] In addition to the cutting positions C1 and C2, the laminate 40 shown in FIG. 3A is also cut at positions to form cut surfaces that will become the electrode lead-out surface 10a and the electrode lead-out surface 10b of the cover layer 15, which will be described later. In this case, the cutting is performed so that the end face of the positive electrode mixture layer is exposed on one cut surface and the end face of the negative electrode mixture layer is exposed on the other cut surface opposite the one cut surface. When the positive electrode mixture layer part and the negative electrode mixture layer part are transferred as described above, their stacking positions are adjusted so that the end face of the positive electrode mixture layer can be exposed on one cut surface and the end face of the negative electrode mixture layer can be exposed on the other cut surface. Of the one cut surface that exposes the end face of the positive electrode mixture layer and the other cut surface that exposes the end face of the negative electrode mixture layer, one becomes the electrode lead-out surface 10a of the cover layer 15, which will be described later, and the other becomes the electrode lead-out surface 10b of the cover layer 15, which will be described later.

[0057] The laminate 40 (FIG. 3(B)) cut as described above is placed flat on a porous ceramic plate and heated, for example, in an air atmosphere at a temperature in the range of 480°C to 520°C for 1 to 10 hours to degrease organic components contained in the laminate 40, such as binder, plasticizer, and dispersant. Furthermore, the laminate 40 is further heated, for example, in a nitrogen atmosphere at a temperature in the range of 600°C to 650°C for 1 to 10 hours to sinter the solid electrolyte, glass, ceramics, and the like contained in the laminate 40.

[0058] As a result, the battery body 10 including the power generating element 14 and cover layer 15 as shown in FIGS. 2(A) and 2(B) is obtained from the laminate 40 as shown in FIG. 3(B). That is, the electrolyte layer 13 of the battery body 10 shown in Figures 2(A) and 2(B) is formed from the electrolyte mixture layer 43 of the laminate 40 shown in Figure 3(B). The electrode layer 11 of the battery body 10 shown in Figures 2(A) and 2(B) is formed from the electrode mixture layer 41 (positive electrode mixture layer or negative electrode mixture layer) of the laminate 40 shown in Figure 3(B). The electrode layer 12 of the battery body 10 shown in Figures 2(A) and 2(B) is formed from the electrode mixture layer 42 (negative electrode mixture layer or positive electrode mixture layer) of the laminate 40 shown in Figure 3(B).

[0059] The power generating element 14 of the battery body 10 shown in Figures 2(A) and 2(B) is formed from the electrode mixture layer 41 and the electrode mixture layer 42 of the laminate 40 shown in Figure 3(B) and the electrolyte mixture layer 43 interposed therebetween. The cover layer 15 of the battery body 10 shown in Figures 2(A) and 2(B), i.e., the cover layer 15 that covers the top and bottom surfaces of the power generating element 14, as well as the end faces 11a of the electrode layers 11, 12a of the electrode layers 12, and the end faces 13a of the electrolyte layers 13 of the power generating element 14, is formed from the cover mixture layer 45 of the laminate 40 shown in Figure 3(B).

[0060] Here, the cut surfaces 40a at the cutting positions C1 and C2 of the laminate 40 shown in Fig. 3(B) become the outer surfaces 15a (side surfaces) of the cover layer 15 shown in Fig. 2(B) above. Furthermore, cut surfaces at other cutting positions (not shown) in the laminate 40 shown in Fig. 3(B) form the electrode lead surface 10a of the cover layer 15 where the end surface 11b of the electrode layer 11 is exposed, and the electrode lead surface 10b of the cover layer 15 where the end surface 12b of the electrode layer 12 is exposed, as shown in Fig. 2(A) above.

[0061] <Formation of external connection terminals> After the battery body 10 is formed, as shown in FIG. 2(A), the external connection terminals 20 and 30 are formed on the electrode lead-out surfaces 10a and 10b of the cover layer 15, respectively.

[0062] As an example, a paste containing a conductive component, such as a metal material such as Ag or a carbon material such as carbon fiber, is applied to the electrode lead-out surface 10a and the electrode lead-out surface 10b, respectively, and then subjected to a heat treatment such as drying, curing, or baking. Then, Ni and Sn are sequentially deposited on the surface of the layer formed by applying the paste and the heat treatment using a plating method. For example, such a method is used to form the external connection terminals 20 and 30. The external connection terminal 20 is connected to the end surface 11b of the electrode layer 11 exposed from the cover layer 15 on the electrode lead-out surface 10a. The external connection terminal 30 is connected to the end surface 12b of the electrode layer 12 exposed from the cover layer 15 on the electrode lead-out surface 10b.

[0063] By the above-described method, the solid state battery 1 having the configuration shown in FIGS. 1, 2(A) and 2(B) is manufactured. As described above, the solid-state battery 1 includes a power generating element 14 including at least one electrode layer 11, one electrode layer 12, and one electrolyte layer 13, each having a different distance Lx from the outer surface 15a (reference position S0) facing the second direction D2 of the cover layer 15 to the end surface 11a, the end surface 12a, and the end surface 13a, as shown in FIG. 2(B).

[0064] Here, the solid-state battery 1 may include a power generating element 14 having a plurality of electrode layers 11, a plurality of electrode layers 12, and a plurality of electrolyte layers 13 inside the battery body 10. In this case, the solid-state battery 1 may include, as layers of the power generating element 14 that are different in distance Lx from the outer surface 15a of the cover layer 15, the electrode layers 11 and 12 and the electrolyte layer 13, which have different polarities. Furthermore, the solid-state battery 1 may include, as layers of the power generating element 14 that are different in distance Lx from the outer surface 15a of the cover layer 15, electrode layers 11 and 12 that have the same polarity and an electrolyte layer 13, or electrode layers 12 and 13 that have the same polarity.

[0065] Fig. 4 is a diagram illustrating the distance from the outer surface of the cover layer to the layer of the power generating element, and is a schematic cross-sectional view of the main parts of the cover layer and the power generating element. For convenience, FIG. 4 illustrates three layers included in the power generating element 14 of the solid-state battery 1: a first electrode layer 51, a second electrode layer 52, and an electrolyte layer 53, which are opposed to each other in the first direction D1. However, the first electrode layer 51, the second electrode layer 52, and the electrolyte layer 53 do not necessarily need to be stacked in the order shown in FIG. 4. The first electrode layer 51 shown in FIG. 4 may be a positive electrode layer or a negative electrode layer. In other words, the first electrode layer 51 may be the electrode layer 11 or the electrode layer 12. The second electrode layer 52 shown in FIG. 4 may be a positive electrode layer or a negative electrode layer. In other words, the second electrode layer 52 may be the electrode layer 11 or the electrode layer 12. That is, the first electrode layer 51 and the second electrode layer 52 shown in FIG. 4 may be electrode layers of opposite polarity or electrode layers of the same polarity.

[0066] 4 illustrates a cover layer 55, which is an embedded layer, as the cover layer 15 that covers the power generating element 14 of the solid-state battery 1. A first end surface 51a of the first electrode layer 51, a second end surface 52a of the second electrode layer 52, and a third end surface 53a of the electrolyte layer 53 are each covered with the cover layer 55. The reference position S0 shown in FIG. 4 corresponds to the outer surface 55a of the cover layer 55 (the outer surface 15a of the cover layer 15) facing the second direction D2.

[0067] Now, the distance Lx from the outer surface 55a of the cover layer 55 to the first end surface 51a of the first electrode layer 51 is defined as a first distance L1, the distance Lx from the outer surface 55a of the cover layer 55 to the second end surface 52a of the second electrode layer 52 is defined as a second distance L2, and the distance Lx from the outer surface 55a of the cover layer 55 to the third end surface 53a of the electrolyte layer 53 is defined as a third distance L3. As shown in Fig. 4, the first electrode layer 51, the second electrode layer 52, and the electrolyte layer 53 are arranged such that the first distance L1, the second distance L2, and the third distance L3 are different from one another.

[0068] For example, when the solid-state battery 1 includes a power generating element 14 having a plurality of electrode layers 11, a plurality of electrode layers 12, and a plurality of electrolyte layers 13, at least a portion of the power generating element 14 includes a first electrode layer 51, a second electrode layer 52, and an electrolyte layer 53 as shown in Fig. 4. That is, the solid-state battery 1 includes, for example, a power generating element 14 having a plurality of electrode layers 11, a plurality of electrode layers 12, and a plurality of electrolyte layers 13, at least a portion of the power generating element 14 including a first electrode layer 51, a second electrode layer 52, and an electrolyte layer 53 in which the first distance L1, the second distance L2, and the third distance L3 are different from one another as shown in Fig. 4.

[0069] 4 as either the positive electrode layer or the negative electrode layer, or the electrode layer 11 or the electrode layer 12, the electrode layer corresponding to the first electrode layer 51 is connected to the external connection terminal 20 or the external connection terminal 30. That is, the electrode layer corresponding to the first electrode layer 51 is connected to the external connection terminal 20 or the external connection terminal 30 at an end surface that faces the third direction D3 orthogonal to the first direction D1 and the second direction D2 and is exposed from the electrode lead-out surface (electrode lead-out surface 10a or 10b) of the cover layer 55 (cover layer 15). Furthermore, in the solid-state battery 1 that includes the second electrode layer 52 as shown in FIG. 4 as either the positive electrode layer or the negative electrode layer, or the electrode layer 11 or the electrode layer 12, the electrode layer corresponding to the second electrode layer 52 is connected to the external connection terminal 20 or the external connection terminal 30. That is, the electrode layer corresponding to the second electrode layer 52 is connected to the external connection terminal 20 or the external connection terminal 30 at an end face that faces the third direction D3 orthogonal to the first direction D1 and the second direction D2 and that is exposed from the electrode lead-out surface (electrode lead-out surface 10a or 10b) of the cover layer 55 (cover layer 15). The end face of the first electrode layer 51 or the second electrode layer 52 that faces the third direction D3 and is connected to the external connection terminal 20 or the external connection terminal 30 in this manner is also referred to as a "fourth end face" here.

[0070] Examples and comparative examples will be described below. 5A and 5B are diagrams illustrating solid-state batteries according to examples and comparative examples. Each of Fig. 5A and Fig. 5B is a schematic cross-sectional view of a main part of an example of a solid-state battery. Each of Fig. 5A and Fig. 5B is a schematic cross-sectional view taken along line L2 in Fig. 1.

[0071] Here, a solid state battery 1 having a configuration as shown in Figures 5(A) and 5(B) will be taken as an example. In the cross-sectional view of the solid state battery 1 taken along the second direction D2, the electrode layer 11, the electrode layer 12, and the electrolyte layer 13 are arranged with a misalignment with each other in the second direction D2.

[0072] 5A, attention is focused on the electrode layers 11 and 12 of opposite polarity among the plurality of electrode layers 11 and the plurality of electrode layers 12 in the power generating element 14 of the solid-state battery 1. Here, among the electrode layers 11 and 12 of opposite polarity, the distance Lx from the outer surface 15a of the cover layer 15, which is the reference position S0, to the end surface is the maximum distance L Max The electrode layer (electrode layer 12 in the example of FIG. 5A) is the electrode layer where the distance Lx from the outer surface 15a to the end surface is the minimum distance L Min Then, the maximum distance L between the selected electrode layers of opposite polarity is determined. Max and the minimum distance L Min Difference L Diff Ask for.

[0073] 5(B), attention is focused on the electrode layers 11 or 12 of the same polarity among the plurality of electrode layers 11 and the plurality of electrode layers 12 in the power generating element 14 of the solid-state battery 1. Here, among the electrode layers 11 or 12 of the same polarity, the distance Lx from the outer surface 15a of the cover layer 15, which is the reference position S0, to the end surface is the maximum distance L Max The electrode layer (electrode layer 11 in the example of FIG. 5B) is the electrode layer where the distance Lx from the outer surface 15a to the end surface is the minimum distance L Min Then, the maximum distance L between the selected electrode layers of the same polarity is determined. Max and the minimum distance L Min Difference L Diff Ask for.

[0074] The distance Lx from the outer surface 15a of the cover layer 15 to the end surface of the electrode layer 11 and the electrode layer 12 is determined by cutting out a cross section of the solid-state battery 1 and measuring the thickness of the cover layer 15 (embedded layer) from the outer surface 15a on the cross section using a microscope.

[0075] In the examples and comparative examples, the maximum distance L Max and the minimum distance L Min and their difference L Diff The solid state batteries 1 of Examples 1-6 (Table 1) and Comparative Examples 1-7 (Table 3) were prepared by changing the maximum distance L Max and the minimum distance L Min and their difference L Diff The solid state batteries 1 of Examples 7 to 13 (Table 2) and Comparative Examples 8 to 11 (Table 4) were prepared by changing the temperature.

[0076] The solid state batteries 1 of Examples 1-13 and Comparative Examples 1-11 were prepared by adjusting the distance Lx from the outer surface 15a of the cover layer 15 to the end surface 11a of the electrode layer 11, the distance Lx from the outer surface 15a of the cover layer 15 to the end surface 12a of the electrode layer 12, and the distance Lx from the outer surface 15a of the cover layer 15 to the end surface 13a of the electrolyte layer 13 by at least one of adjusting the printing area of ​​the positive electrode paste and cover paste of the positive electrode mixture layer part, the printing area of ​​the negative electrode paste and cover paste of the negative electrode mixture layer part, and the printing area of ​​the electrolyte paste and cover paste of the electrolyte mixture layer part in the above-mentioned manufacturing method, and adjusting the stacking positions of the positive electrode mixture layer part, the negative electrode mixture layer part, and the electrolyte mixture layer part.

[0077] The prepared solid state battery 1 was evaluated for the occurrence of cracks during firing and for the occurrence of defects during mounting. In the solid-state battery 1, a cover layer 15 with insulating properties and low moisture and gas permeability is used on the surface of the battery body 10. However, if cracks occur in this cover layer 15, external moisture and gas may penetrate into the battery body 10 and react with the power-generating element 14, potentially resulting in insufficient charge / discharge characteristics. Furthermore, the potential difference between the positive and negative electrodes cannot be maintained constant at open-circuit voltage, which may lead to self-discharge, short circuits, and other problems. Furthermore, the positive electrode material, negative electrode material, or electrolyte material used in the power-generating element 14 may decompose due to reactions with moisture or other substances that penetrate through cracks. If these decomposition products are released to the outside through cracks, they may contaminate or destroy other electronic components surrounding the solid-state battery 1 mounted on a circuit board, resulting in defects. Thus, the occurrence of cracks in the solid-state battery 1 can significantly affect its quality. In light of these points, the prepared solid-state batteries 1 were evaluated for the presence or absence of cracks during firing and defects during assembly.

[0078] The maximum distance L between the opposite polarity electrode layers of the solid state battery 1 of Examples 1-6 Max [μm] and minimum distance L Min [μm] and their difference L Diff [μm] is shown in Table 1. Table 1 also shows the maximum distance L Max Maximum and minimum values ​​of, minimum distance L Min The maximum and minimum values ​​of and the difference L Diff The maximum and minimum values ​​are also shown.

[0079] [Table 1]

[0080] The maximum distance L of the same polarity electrode layers of the solid state batteries 1 of Examples 7-13 Max [μm] and minimum distance L Min [μm] and their difference L Diff [μm] is shown in Table 2. Table 2 also shows the maximum distance L Max Maximum and minimum values ​​of, minimum distance L Min The maximum and minimum values ​​of and the difference LDiff The maximum and minimum values ​​are also shown.

[0081] [Table 2]

[0082] The maximum distance L between the opposite polarity electrode layers of the solid state battery 1 of Comparative Example 1-7 Max [μm] and minimum distance L Min [μm] and their difference L Diff [μm] is shown in Table 3. Table 3 also shows the maximum distance L Max Maximum and minimum values ​​of, minimum distance L Min The maximum and minimum values ​​of and the difference L Diff Table 3 also shows the maximum and minimum values ​​of the solid state batteries 1 of Comparative Examples 1-7, and whether or not cracks occurred during firing and whether or not defects occurred during mounting.

[0083] [Table 3]

[0084] The maximum distance L of the same polarity electrode layers of the solid state batteries 1 of Comparative Examples 8-11 Max [μm] and minimum distance L Min [μm] and their difference L Diff [μm] is shown in Table 4. Table 4 also shows the maximum distance L Max Maximum and minimum values ​​of, minimum distance L Min The maximum and minimum values ​​of and the difference L Diff Table 4 also shows the maximum and minimum values ​​of the solid state batteries 1 of Comparative Examples 8 to 11, and whether or not cracks occurred during firing and whether or not defects occurred during mounting.

[0085] [Table 4]

[0086] In the solid state batteries 1 of Examples 1-6 and 7-13, neither cracks during firing nor defects during mounting were observed. In contrast, in the solid state batteries 1 of Comparative Examples 1-7 and 8-11, at least one of cracks during firing and defects during mounting was observed.

[0087] Here, the maximum distance L between the opposite polarity electrode layers of the solid state battery 1 of Examples 1-6 Max , minimum distance L Min and the difference L Diff and the maximum distance L of the opposite polarity electrode layers of the solid state batteries 1 of Comparative Examples 1-7. Max , minimum distance L Min and the difference L Diff The maximum and minimum values ​​of each are shown in Table 5.

[0088] [Table 5]

[0089] In addition, the maximum distance L of the same polarity electrode layers of the solid state batteries 1 of Examples 7-13 Max , minimum distance L Min and the difference L Diff and the maximum distance L of the same polarity electrode layers of the solid state batteries 1 of Comparative Examples 8-11. Max , minimum distance L Min and the difference L Diff The maximum and minimum values ​​of each are shown in Table 6.

[0090] [Table 6]

[0091] Figure 6 shows the maximum distance L Max , minimum distance L Min and their difference L Diff 6A is a diagram showing the relationship between the maximum distance L Max , minimum distance L Min and the difference L DiffThe graph in FIG. 6(B) shows the relationship between the maximum distance L Max , minimum distance L Min and the difference L Diff This shows the relationship between the results of Table 6.

[0092] From Table 5 and FIG. 6(A), for the electrode layers 11 and 12 of opposite polarity, such as the solid state batteries 1 of Examples 1-6, the maximum distance L Max is in the range of 102 μm to 356 μm, and the minimum distance L Min is in the range of 84 μm or more and 246 μm or less, and the difference L Diff When the thickness is in the range of 18 μm or more and 270 μm or less, the occurrence of cracks during firing and defects during mounting can be effectively suppressed.

[0093] Therefore, the power generating element 14 and the cover layer 15 are spaced apart from each other by the maximum distance L Max , minimum distance L Min and the difference L Diff By forming the solid state battery 1 so that the relationship in Table 5 and FIG. 6(A) is satisfied, the occurrence of cracks during firing and defects during mounting can be suppressed, and a high-quality solid state battery 1 can be realized.

[0094] Furthermore, from Table 6 and FIG. 6(B), it can be seen that the maximum distance L Max is in the range of 99 μm to 198 μm, and the minimum distance L Min is in the range of 83 μm or more and 126 μm or less, and the difference L Diff When the thickness is in the range of 3 μm or more and 104 μm or less, the occurrence of cracks during firing and defects during mounting can be effectively suppressed.

[0095] Therefore, the power generating element 14 and the cover layer 15 are spaced apart from each other by the maximum distance L Max , minimum distance L Min and the difference L DiffBy forming the solid state battery 1 so that the relationship in Table 6 and FIG. 6(B) is satisfied, it is possible to realize a high-quality solid state battery 1 in which the occurrence of cracks during firing and defects during mounting are suppressed. [Explanation of symbols]

[0096] 1 solid state battery 10 Battery body 10a, 10b Electrode extraction surface 11, 12 electrode layer 11a, 11b, 11c, 12a, 12b, 12c, 13a End face 13, 53 electrolyte layer 14 Power generation elements 15, 55 cover layer 15a, 55a external surface 20, 30 External connection terminal 40 laminate 40a cutting surface 41, 42 Electrode mixture layer 43 Electrolyte mixture layer 45 Cover mixture layer 51 1st electrode layer 51a 1st end surface 52 Second electrode layer 52a 2nd end face 53a 3rd end face C1, C2 cutting position D1 1st direction D2 2nd direction D3 Third direction L1 1st distance L2 2nd distance L3 Third distance Lx distance S0 reference position

Claims

1. a power generating element including a first electrode layer, a second electrode layer, and an electrolyte layer that face each other in a first direction; an insulating cover layer that covers a first end face of the first electrode layer facing a second direction orthogonal to the first direction, a second end face of the second electrode layer facing the second direction, and a third end face of the electrolyte layer facing the second direction, and has an electrode lead-out surface from which a fourth end face of the first electrode layer or the second electrode layer facing a third direction orthogonal to the first direction and the second direction is exposed; an external connection terminal provided on the electrode lead-out surface and connected to the fourth end surface; Including, a first distance from an outer surface of the cover layer facing the second direction to the first end surface, a second distance from the outer surface to the second end surface, and a third distance from the outer surface to the third end surface are different from one another.

2. the power generating element is formed by stacking a plurality of electrode layers and a plurality of electrolyte layers alternately in the first direction, the cover layer covers end surfaces of the plurality of electrode layers facing the second direction and end surfaces of the plurality of electrolyte layers facing the second direction; the plurality of electrode layers includes a plurality of opposite polarity electrode layers, the first electrode layer is an electrode layer in which the first distance is the largest among the plurality of opposite polarity electrode layers, and the largest distance is in the range of 102 μm or more and 356 μm or less; the second electrode layer is an electrode layer in which the second distance is the smallest distance among the plurality of opposite polarity electrode layers, and the smallest distance is in the range of 84 μm or more and 246 μm or less; The solid-state battery according to claim 1 , wherein the difference between the maximum distance and the minimum distance is in the range of 18 μm to 270 μm.

3. the power generating element is formed by stacking a plurality of electrode layers and a plurality of electrolyte layers alternately in the first direction, the cover layer covers end surfaces of the plurality of electrode layers facing the second direction and end surfaces of the plurality of electrolyte layers facing the second direction; the plurality of electrode layers includes a plurality of same-polarity electrode layers, the first electrode layer is an electrode layer in which the first distance is the largest among the plurality of same-polarity electrode layers, and the largest distance is in the range of 99 μm or more and 198 μm or less; the second electrode layer is an electrode layer in which the second distance is the smallest distance among the plurality of same-polarity electrode layers, and the smallest distance is in the range of 83 μm to 126 μm, The solid-state battery according to claim 1 , wherein the difference between the maximum distance and the minimum distance is in the range of 3 μm to 104 μm.

4. The solid-state battery according to claim 1 , wherein the cover layer comprises glass, ceramic, or a solid electrolyte.

5. forming a power generating element including a first electrode layer, a second electrode layer, and an electrolyte layer that face each other in a first direction; forming an insulating cover layer that covers a first end face of the first electrode layer facing a second direction perpendicular to the first direction, a second end face of the second electrode layer facing the second direction, and a third end face of the electrolyte layer facing the second direction, and that has an electrode extraction surface that exposes a fourth end face of the first electrode layer or the second electrode layer facing a third direction perpendicular to the first direction and the second direction; forming an external connection terminal on the electrode lead-out surface to be connected to the fourth end surface; Including, a first distance from an outer surface of the cover layer facing the second direction to the first end surface, a second distance from the outer surface to the second end surface, and a third distance from the outer surface to the third end surface are different from one another.

6. preparing a first electrode paste for forming the first electrode layer, a second electrode paste for forming the second electrode layer, an electrolyte paste for forming the electrolyte layer, and a cover paste for forming the cover layer; a step of printing the first electrode paste and then printing the cover paste on the outside thereof to form a first part including a first electrode mixture layer formed from the first electrode paste and a first cover mixture layer formed from the cover paste; a step of printing the second electrode paste and then printing the cover paste on the outside thereof to form a second part including a second electrode mixture layer formed from the second electrode paste and a second cover mixture layer formed from the cover paste; printing the electrolyte paste and then printing the cover paste on the outside of the electrolyte paste to form a third part including an electrolyte mixture layer formed from the electrolyte paste and a third cover mixture layer formed from the cover paste; forming a laminate in which the first part, the second part, and the third part are stacked in the first direction so that the first electrode mixture layer, the second electrode mixture layer, and the electrolyte mixture layer have a region where they face each other, and so that the first cover mixture layer, the second cover mixture layer, and the third cover mixture layer have a region where they face each other; cutting the laminate at regions where the first cover mixture layer, the second cover mixture layer, and the third cover mixture layer of the first part, the second part, and the third part face each other, and forming the cut surfaces as the outer surfaces; firing the cut laminate to form the first electrode layer from the first electrode mixture layer, the second electrode layer from the second electrode mixture layer, the electrolyte layer from the electrolyte mixture layer, and the cover layer from the first cover mixture layer, the second cover mixture layer, and the third cover mixture layer; Including, 6. The method for manufacturing a solid-state battery according to claim 5, wherein the first distance, the second distance, and the third distance are adjusted by at least one of adjusting a printing area of ​​the first electrode paste and the cover paste of the first part, a printing area of ​​the second electrode paste and the cover paste of the second part, and a printing area of ​​the electrolyte paste and the cover paste of the third part, and adjusting stacking positions of the first part, the second part, and the third part.

Images