All-solid-state battery

Abstract

The present disclosure relates to an all-solid-state battery. The all-solid-state battery includes: a first electrode layer including a first electrode and a first margin portion, the first electrode including a first electrode active material and being quadrangular, the first margin portion being quadrangular, the first electrode layer being formed by connecting the first electrode and the first margin portion; a second electrode layer including a second electrode and a second margin portion, the second electrode having a quadrangular shape in a plan view and including a second electrode active material, the second electrode active material having a lower average operating potential than the first electrode active material, the second margin portion being connected to one side of a quadrangular shape of the second electrode, the quadrangular shape having a first side and a second side adjacent to the one side, the second margin portion extending to the first side; and a solid electrolyte layer disposed between the first electrode layer and the second electrode layer.

Description

Technical Field

[0001] One aspect of the present invention relates to an all-solid-state battery. Background Technology

[0002] In recent years, secondary batteries have been used in various fields. However, secondary batteries using electrolytes suffer from problems such as electrolyte leakage. Therefore, the development of all-solid-state batteries, which include solid electrolytes and other solid components, is underway.

[0003] To achieve higher energy density in this field of all-solid-state batteries, stacked all-solid-state batteries have been proposed, which include two or more battery cells (also known as single cells), each of which consists of a positive electrode, a solid electrolyte layer and a negative electrode (see, for example, Japanese Patent Application Publication No. 2007-80812 (hereinafter referred to as Document 1), Japanese Patent Application Publication No. 2014-192041 (hereinafter referred to as Document 2), International Publication No. 2020 / 179934 (hereinafter referred to as Document 3) and Japanese Patent Application Publication No. 2015-125893 (hereinafter referred to as Document 4)). Summary of the Invention

[0004] According to one aspect of the present invention, an all-solid-state battery is provided, the all-solid-state battery comprising: a first electrode layer, the first electrode layer including a first electrode and a first blank portion, the first electrode including a first electrode active material and being quadrilateral in a plan view, the first blank portion being quadrilateral in a plan view, the first electrode layer being formed by connecting the first electrode and the first blank portion; a second electrode layer, the second electrode layer including a second electrode and a second blank portion, the second electrode having a quadrilateral shape in a plan view and including a second electrode active material, the second electrode active material having a lower average operating potential than the first electrode active material, the second blank portion being connected to one side of the quadrilateral shape of the second electrode, the quadrilateral shape having a first side and a second side adjacent to the first side, the second blank portion extending to the first side; and a solid electrolyte layer disposed between the first electrode layer and the second electrode layer.

[0005] According to one aspect of the present invention, an all-solid-state battery is provided, the all-solid-state battery comprising: a first electrode layer, the first electrode layer comprising a first electrode and a first blank portion, the first electrode comprising a first electrode active material and being quadrilateral in a planar view, the first blank portion being quadrilateral in a planar view, the first electrode layer being formed by connecting the first electrode and the first blank portion, the first electrode active material being capable of absorbing and releasing lithium ions, the first electrode active material being a lithium oxide and comprising at least one element selected from the group consisting of titanium, vanadium, manganese, iron, cobalt, nickel, phosphorus and silicon; and a second electrode layer, the second electrode layer comprising a second electrode and a second blank portion, the second electrode being quadrilateral in a planar view. The diagram shows a quadrilateral shape and includes a second electrode active material having a lower average operating potential than the first electrode active material. A second blank portion is connected to one side of the quadrilateral shape of the second electrode. The quadrilateral shape has a first side and a second side adjacent to the first side. The second blank portion extends to the first side. The second electrode active material is capable of absorbing and releasing lithium ions. The second electrode active material is any one of an oxide, a conductive carbon material, a single metal, or an alloy, wherein the alloy contains at least one element selected from the group consisting of lithium, titanium, niobium, tantalum, and hafnium. A solid electrolyte layer is also included, disposed between the first electrode layer and the second electrode layer. Attached Figure Description

[0006] Figure 1A A schematic cross-sectional view of the basic structure of an all-solid-state battery is shown. Figure 1B The positive electrode, negative electrode, and solid electrolyte layer are shown. Figure 2 A three-dimensional view of a multilayer chip in which multiple battery cells are stacked is shown; Figure 3 It shows along Figure 2 A cross-sectional view taken from line AA in the diagram; Figure 4 It shows along Figure 2 A cross-sectional view taken from line BB in the middle; Figure 5A An enlarged cross-section of the first end blank portion is shown; Figure 5B An enlarged cross-sectional view of the remaining portion at the second end is shown; Figure 6A An enlarged cross-sectional view of the blank area on the first side is shown; Figure 6B An enlarged cross-sectional view of the blank area on the second side is shown; Figure 7 A three-dimensional view of a stacked all-solid-state battery is shown; Figure 8 A multi-layered structure is shown; Figure 9 A flowchart illustrating the manufacturing method of an all-solid-state battery is shown. Figure 10 The stacking process is shown; Figure 11 The cutting process is shown; Figure 12 Comparative Example 1 is shown; Figure 13 Comparative Example 2 is shown; and Figure 14 Comparative Example 3 is shown. Detailed Implementation

[0007] Document 1 discloses an internal electrode structure for an all-solid-state battery, which has a stacked structure similar to that of a multilayer ceramic capacitor. When the positive and negative electrode portions are stacked with a solid electrolyte layer sandwiched between them, gaps appear in the total thickness between the electrode intersections and non-intersections of the positive and negative electrode portions, causing deformation. Because such deformation can lead to cracks and short circuits, it is effective to provide blank areas around the electrode portions, as shown in Document 2. According to Document 2, when viewed from above, the blank areas have a transverse U-shaped shape surrounding three sides of the rectangular electrode portion.

[0008] If the shrinkage behavior of the electrode portion and the blank area is mismatched during heat treatment, problems such as cracking may occur during sintering. Various simulations have shown, as illustrated in Reference 2, that even a slight mismatch in the thermal shrinkage of the electrode portion can cause internal stress in the transverse U-shaped blank area formed around the outer periphery of the electrode portion during sintering. Therefore, a structure that can reduce internal stress is desired.

[0009] Considering this, as described in Reference 3, it can be assumed that by exposing the internal electrodes to the side surfaces of the stacked battery, the boundary between the internal electrodes and the blank areas can be reduced, thereby reducing internal stress. However, this increases the amount of airborne moisture adhering to the internal electrodes during the manufacturing process, leading to a high, defective drying rate during the drying process used to remove the adhering moisture. Poor drying results in a decrease in the battery's charge / discharge coulombic efficiency. This is because the moisture adhering to the internal electrodes is reduced and decomposed due to the low potential of the electrode active material after charging.

[0010] The embodiments will now be described with reference to the accompanying drawings.

[0011] (Implementation Method) Figure 1A A schematic cross-sectional view of the basic structure of the all-solid-state battery 100 is shown. Figure 1AAs shown, the all-solid-state battery 100 has a structure in which a positive electrode 10 (first internal electrode) and a negative electrode 20 (second internal electrode) sandwich a solid electrolyte layer 30 in between. The positive electrode 10 is disposed on a first main surface of the solid electrolyte layer 30. The negative electrode 20 is disposed on a second main surface of the solid electrolyte layer 30. For example, the positive electrode 10, the negative electrode 20, and the solid electrolyte layer 30 have a sintered body formed by sintering powder material.

[0012] The main component of the solid electrolyte layer 30 is a solid electrolyte with ionic conductivity. The solid electrolyte of the solid electrolyte layer 30 is an oxide-based solid electrolyte with lithium-ion conductivity. The solid electrolyte is, for example, a phosphate-based electrolyte with a NASICON crystal structure. For example, the solid electrolyte of the solid electrolyte layer 30 is an oxide-based solid electrolyte with lithium-ion conductivity. There are no limitations on the phosphate. For example, the phosphate is, for example, a complex salt of phosphate and Ti (e.g., LiTi2(PO4)3). Alternatively, at least a portion of the Ti can be replaced with a transition metal with a valence of 4 (such as Ge, Sn, Hf, or Zr). To increase the amount of Li, a portion of the Ti can be replaced with a transition metal with a valence of 3 (such as Al, Ga, In, Y, or La). Specifically, the phosphate is Li 1＋x Al x Ge 2-x (PO4)3, Li 1＋x Al x Zr 2-x (PO4)3, Li 1＋x Al x T 2-x (PO4)3, etc.

[0013] like Figure 1B As shown, the positive electrode 10 has a structure in which a positive electrode active material 11 (first electrode active material), a solid electrolyte 12, a conductive additive 13, etc., are dispersed. The negative electrode 20 has a structure in which a negative electrode active material 21 (second electrode active material), a solid electrolyte 22, a conductive additive 23, etc., are dispersed. The positive electrode 10 includes the positive electrode active material 11, and the negative electrode 20 includes the negative electrode active material 21, thereby allowing the all-solid-state battery 100 to be used as a secondary battery. The positive electrode 10 includes the solid electrolyte 12, and the negative electrode 20 includes the solid electrolyte 22, thereby achieving ionic conductivity in the positive electrode 10 and the negative electrode 20. The positive electrode 10 includes the conductive additive 13, and the negative electrode 20 includes the conductive additive 23, thereby achieving conductivity in the positive electrode 10 and the negative electrode 20. The solid electrolytes 12 and 22 can be, for example, the same solid electrolyte as the solid electrolyte layer 30, or they can be different solid electrolytes.

[0014] The positive electrode active material 11 is an electrode active material used as the positive electrode. The average working potential of the positive electrode active material 11 is not particularly limited, but in the present embodiment, for example, relative to Li / Li ＋ is 3 V or higher.

[0015] Here, the average working potential refers to the average discharge potential of the electrode active material when the battery discharges from the fully charged state to the discharge cut-off voltage under standard conditions. The discharge potential is based on the redox potential of the metallic lithium electrode. The average working potential can be measured by charging and discharging a battery in which an electrode containing an electrode active material with an unknown working potential and an electrode with a known working potential are combined as the counter electrode.

[0016] The positive electrode active material 11 is, for example, a lithium-containing oxide electrode active material that can absorb and release lithium ions and contains at least one element selected from the group consisting of titanium, vanadium, manganese, iron, cobalt, nickel, phosphorus, and silicon.

[0017] The positive electrode active material 11 is, for example, an electrode active material having an olivine-type crystal structure. The positive electrode active material is, for example, a phosphate containing a transition metal and lithium. The olivine-type crystal structure is the crystal of natural olivine and can be determined by X-ray diffraction.

[0018] A typical example of the positive electrode active material having an olivine crystal structure is LiCoPO4 containing Co. A phosphate can also be used, in which Co in the chemical formula is replaced by a transition metal. The ratio of Li and PO4 can vary according to the valence. It is preferable to use Co, Mn, Fe, Ni, etc. as the transition metal. For example, LiFePO4, LiMnPO4, Li 1-y Co 1-x+y Ni x P 1- y Si y O4 (0 < x ≤ 1, 0 ≤ y < 0.1), etc.

[0019] Alternatively, the positive electrode active material 11 can be a layered rock salt-type active material such as LiCoO2 or LiCo 1-x-y Ni x Mn y O2 (0 < x + y ≤ 1), or a spinel-type active material such as LiMn2O4 or LiNi 0.5 Mn 1.5 O4.

[0020] The negative electrode active material 21 uses an electrode active material that functions as the negative electrode. The average working potential of the negative electrode active material 21 is not particularly limited, but is lower than the average working potential of the positive electrode active material 11. For example, the average working potential of the negative electrode active material 21 relative to Li / Li＋ It is 2.4 V or less. From the perspective of improving the battery voltage and energy density of the all-solid-state battery 100, the average operating potential of the negative electrode active material 21 relative to Li / Li ＋ Preferably, the voltage is less than 2 V. For example, an electrode active material capable of absorbing and releasing lithium ions can be used as the negative electrode active material 21, said electrode active material being any one of oxides, conductive carbon materials, elemental metals, and alloys containing at least one element selected from the group consisting of lithium, titanium, niobium, tantalum, and hafnium. For example, TiO2, Li4Ti5O can be used. 12 Compounds based on Li-Al-Co-Ti-PO, compounds based on Ti-Ta-Nb-O, compounds based on Al-Nb-Hf-Ta-O, graphite, hard carbon, etc., are used as negative electrode active materials 21.

[0021] Carbon materials or similar materials are used as conductive additives 13 and 23. Metals can also be used as conductive additives 13 and 23. Examples of conductive additive metals are, for example, Pd, Ni, Cu, Fe, or alloys containing two or more of these metals.

[0022] In this embodiment, the average operating potential of the negative electrode active material 21 is lower than the average operating potential of the positive electrode active material 11, so that the positive electrode 10 is used as the positive electrode and the negative electrode 20 is used as the negative electrode. However, at least one of the positive electrode active material 11 and the negative electrode active material 21 may contain multiple types of electrode active materials. In this case, the total average operating potential of the negative electrode 20 is lower than the total average operating potential of the positive electrode 10.

[0023] Figure 2 This is a 3D view of a multilayer chip 60 containing multiple battery units stacked together. Figure 3 It is along Figure 2 The cross-sectional view taken from line AA in the diagram. Figure 4 It is along Figure 2 The cross-sectional view is taken from line BB in the figure. The multilayer chip 60 has a generally cuboid shape. The multilayer chip 60 has an upper surface F1 and a lower surface F2 at both ends of the stacking direction of each layer, a first end face E1 and a second end face E2 facing each other, and a first side surface S1 and a second side surface S2 facing each other.

[0024] Note that in Figures 2 to 4 In the diagram, the Z-axis direction (first direction) is the stacking direction, and it is the direction in which the upper surface F1 and the lower surface F2 of the multilayer chip 60 face each other. The X-axis direction (second direction) is the direction in which the first end face E1 and the second end face E2 of the multilayer chip 60 face each other. The Y-axis direction (third direction) is the direction in which the first side surface S1 and the second side surface S2 face each other. The X-axis direction, Y-axis direction, and Z-axis direction are orthogonal to each other.

[0025] In the following description, components having the same composition range as the all-solid-state battery 100 are indicated by the same reference numerals, and detailed descriptions thereof will be omitted.

[0026] In the multilayer chip 60, the positive electrode 10 and the negative electrode 20 are alternately stacked, and each solid electrolyte layer 30 is inserted between them. The X-axis edge of the positive electrode 10 extends to the first end face E1 of the multilayer chip 60, but not to the second end face E2. The X-axis edge of the negative electrode 20 extends to the second end face E2 of the multilayer chip 60, but not to the first end face E1. The solid electrolyte layer 30 extends from the first end face E1 to the second end face E2. In this way, the multilayer chip 60 has a structure in which multiple battery cells are stacked. Here, the case where they are stacked alternately will be described, but in some parts, the positive electrode 10, the negative electrode 20, and the solid electrolyte layer 30 can be appropriately stacked continuously.

[0027] A capping layer 50 is stacked on the upper surface of the multilayer portion comprising the positive electrode 10, the solid electrolyte layer 30, and the negative electrode 20. The capping layer 50 is in contact with the topmost electrode portion (positive electrode 10 or negative electrode 20) and also with a portion of the solid electrolyte layer 30. Another capping layer 50 is also stacked on the lower surface of the multilayer portion. The capping layer 50 is in contact with the bottommost electrode portion (positive electrode 10 or negative electrode 20) and also with a portion of the solid electrolyte layer 30. For example, the capping layer 50 is a sintered body obtained by sintering powder material.

[0028] like Figure 3 As shown, the portion where the positive electrode 10 and the negative electrode 20 face each other is the portion that generates battery capacity. Therefore, this portion is referred to as the battery capacity portion 70. In other words, the battery capacity portion 70 is the portion where two adjacent electrode portions, pulled to different end faces, face each other.

[0029] The portion near the first end face E1 where the positive electrode 10 faces each other and the negative electrode 20 is not inserted between them is called the first end blank 81. Furthermore, the portion near the second end face E2 where the negative electrode 20 faces each other and the positive electrode 10 is not inserted between them is called the second end blank 82. In other words, the end blank is a portion in which electrode portions drawn towards the same end face face each other, and there are no electrode portions drawn towards different end faces between them. The first end blank 81 and the second end blank 82 are portions that do not contribute to battery capacity.

[0030] like Figure 4As shown, in the multilayer chip 60, the positive electrode 10 extends to both the first side surface S1 and the second side surface S2 of the multilayer chip 60. Therefore, the positive electrode 10 extends to both the first side surface S1 and the second side surface S2, and is exposed from both the first side surface S1 and the second side surface S2. On the other hand, the negative electrode 20 does not extend to either the first side surface S1 or the second side surface S2 of the multilayer chip 60. Therefore, the negative electrode 20 is not exposed from either the first side surface S1 or the second side surface S2.

[0031] In the multilayer chip 60, the portion extending from the first side surface S1 to the battery capacity portion 70 (or up to the negative electrode 20) is referred to as the first side blank portion 91. In the multilayer chip 60, the portion extending from the second side surface S2 to the battery capacity portion 70 (or up to the negative electrode 20) is referred to as the second side blank portion 92. In other words, the first side blank portion 91 and the second side blank portion 92 are portions that are configured to cover the ends of the negative electrode 20 stacked in the multilayer body and extend towards both sides.

[0032] Figure 5A This is an enlarged cross-sectional view of the first end blank portion 81. In the first end blank portion 81, the positive electrode 10 extends to the first end face E1, but the negative electrode 20 does not extend to the first end face E1. The negative electrode blank portion 95b (second blank portion) is disposed in the same layer as the negative electrode 20. This structure reduces the height difference between the battery capacity portion 70 and the first end blank portion 81.

[0033] Figure 5B This is an enlarged cross-sectional view of the second end blank portion 82. In the second end blank portion 82, the negative electrode 20 extends to the second end face E2, while the positive electrode 10 does not extend to the second end face E2. The positive electrode blank portion 95a (first blank portion) is disposed in the same layer as the positive electrode 10. This structure reduces the height difference between the battery capacity portion 70 and the second end blank portion 82.

[0034] Figure 6A This is an enlarged cross-sectional view of the first side blank portion 91. In the first side blank portion 91, the positive electrode 10 extends to the first end face E1, while the negative electrode 20 does not extend to the first end face E1. The negative electrode blank portion 95b is disposed in the same layer as the negative electrode 20. This structure reduces the height difference between the battery capacity portion 70 and the first end blank portion 81.

[0035] Figure 6B This is an enlarged cross-sectional view of the second side blank portion 92. In the second side blank portion 92, the positive electrode 10 extends to the second end face E2, while the negative electrode 20 does not extend to the second end face E2. The negative electrode blank portion 95b is disposed in the same layer as the negative electrode 20. This structure reduces the height difference between the battery capacity portion 70 and the second end blank portion 82.

[0036] The positive electrode blank portion 95a and the negative electrode blank portion 95b are made of, for example, a composite of a solid electrolyte and insulating inorganic particles. There are no particular limitations on the solid electrolyte used in the positive electrode blank portion 95a; however, in order to make the sintering initiation temperature and sintering shrinkage rate of the positive electrode blank portion 95a as close as possible to the sintering initiation temperature and sintering shrinkage rate of the positive electrode 10, it is preferable that the material has the same crystal structure and the same composition as the solid electrolyte 12 in the positive electrode 10. Alternatively, the solid electrolyte used in the positive electrode blank portion 95a is preferably a material having the same crystal structure and the same composition as the solid electrolyte in the solid electrolyte layer 30. There are no particular limitations on the solid electrolyte used in the negative electrode blank portion 95b; however, in order to make the sintering initiation temperature and sintering shrinkage rate of the negative electrode blank portion 95b as close as possible to the sintering initiation temperature and sintering shrinkage rate of the negative electrode 20, it is preferably a material having the same crystal structure and the same composition as the solid electrolyte 22 in the negative electrode 20. Alternatively, the solid electrolyte used in the negative electrode blank 95b is preferably a material having the same crystal structure and composition as the solid electrolyte in the solid electrolyte layer 30. For example, the insulating inorganic particles are made of a material that does not act as an active material, such as alumina or zirconium oxide.

[0037] Figure 7 This is a 3D diagram of a 100A stacked all-solid-state battery. (See diagram below.) Figure 7 As shown, the all-solid-state battery 100a has a configuration in which a first external electrode 41 (first terminal) and a second external electrode 42 (second terminal) are disposed on a multilayer chip 60. Note that... Figure 7 It uses a 100A solid-state battery for up-down display, so the upper surface is the lower surface F2, and the lower surface is the upper surface F1.

[0038] The first external electrode 41 is configured to contact the first end face E1, and the second external electrode 42 is configured to contact the second end face E2. Therefore, the first external electrode 41 is connected to each positive electrode 10 and serves as the positive terminal. The second external electrode 42 is connected to each negative electrode 20 and serves as the negative terminal. The first external electrode 41 is connected to the positive electrode 10 and also contacts the solid electrolyte layer 30 and the negative electrode blank portion 95b. The second external electrode 42 is connected to the negative electrode 20 and also contacts the solid electrolyte layer 30 and the positive electrode blank portion 95a.

[0039] The first external electrode 41 may cover the entire first end face E1 or only a portion of the first end face E1. The second external electrode 42 may cover the entire second end face E2 or only a portion of the second end face E2. The first external electrode 41 and the second external electrode 42 extend to the lower surface F2. However, to prevent short circuits, the first external electrode 41 and the second external electrode 42 are spaced apart from each other at the lower surface F2. Furthermore, the first external electrode 41 and the second external electrode 42 are not disposed on the first side surface S1 or the second side surface S2.

[0040] The all-solid-state battery 100a according to this embodiment will now be described. Figure 8 As shown, in the plan view along the Z-axis, the positive electrode 10, including the positive electrode active material 11, is a quadrilateral, and the positive electrode blank portion 95a is also a quadrilateral. There are no particular restrictions on the quadrilateral shape, but a rectangle is an example. However, in this case, the apex angle of the rectangle can deviate from 90° by approximately ±10°, and the length of the opposite sides can deviate by approximately ±10%. Because the positive electrode 10 and the positive electrode blank portion 95a are arranged in the same layer, the layer formed by the positive electrode 10 and the positive electrode blank portion 95a is also called the positive electrode layer. The positive electrode layer forms a quadrilateral in the plan view by connecting the positive electrode 10 and the positive electrode blank portion 95a along a common edge (the edge on the second end face E2 side). The positive electrode 10 and the positive electrode blank portion 95a can be directly connected along the common edge (the edge on the second end face E2 side), or they can be indirectly connected through a gap or intermediate layer.

[0041] Next, in the plan view along the Z-axis, the negative electrode 20 forms a quadrilateral. Because the negative electrode 20 and the negative electrode blank portion 95b are arranged in the same layer, the layer formed by the negative electrode 20 and the negative electrode blank portion 95b is also called the negative electrode layer. In the plan view, the negative electrode 20 and the negative electrode blank portion 95b are connected by a common edge (the edge on the first end face E1 side), and the negative electrode blank portion 95b extends to at least one of the edges on the first side face S1 side and the second side face S2 side of the negative electrode 20. Figure 8 In the example, the negative electrode blank portion 95b extends to both the edge of the first side surface S1 and the edge of the second side surface S2 of the negative electrode 20.

[0042] This configuration allows for a smaller interface between the remaining portion and the positive electrode compared to when both the positive and negative electrode layers have a transverse U-shape. This reduces the impact of thermal shrinkage mismatch during sintering. Consequently, defects such as cracks and warping can be eliminated.

[0043] Furthermore, the negative electrode blank portion 95b extends to at least one of the edges on the first side surface S1 and the second side surface S2 of the negative electrode 20, and the negative electrode 20 includes a negative electrode active material 21 having an average operating potential lower than that of the positive electrode active material 11. In this case, the adhesion of moisture that is easily reduced and decomposed due to the low potential of the electrode active material after charging to the negative electrode 20 is suppressed, thereby suppressing the degradation of the electrical characteristics of the all-solid-state battery 100a, even if the drying defect rate is high during the manufacturing process.

[0044] As a result, it is possible to suppress the deterioration of electrical properties while eliminating defects such as cracks and warping.

[0045] To prevent moisture from adhering to the negative electrode 20, such as Figure 8 As shown, preferably, the negative electrode blank portion 95b extends along the X-axis direction to contact the entire edge of the negative electrode blank portion 95b on the first side surface S1 side and the entire edge of the negative electrode blank portion 95b on the second side surface S2 side.

[0046] The multilayer body (multilayer chip 60) is formed by stacking multiple positive electrode layers including a positive electrode 10 and a positive electrode blank 95a, multiple negative electrode layers including a negative electrode 20 and a negative electrode blank 95b, and multiple solid electrolyte layers. In a planar view along the Z-axis, the four overlapping sides of the quadrilaterals of the positive electrode layer, the negative electrode layer, and the solid electrolyte layer 30 form the external shape of the multilayer body (first side surface S1, second side surface S2, first end face E1, and second end face E2). Therefore, in a planar view along the Z-axis, the quadrilaterals of the positive electrode layer, the negative electrode layer, and the solid electrolyte layer 30 substantially overlap.

[0047] From the viewpoint of sufficiently suppressing moisture adhesion to the negative electrode 20, in a plan view along the Z-axis, the width of the negative electrode blank portion 95b in the Y-axis direction is preferably 50 μm or greater, more preferably 100 μm or greater, and even more preferably 300 μm or greater. On the other hand, if the width of the negative electrode blank portion 95b is too large, the battery capacity may be reduced. Therefore, in a plan view along the Z-axis, the width of the negative electrode blank portion 95b in the Y-axis direction is preferably 1000 μm or less, more preferably 800 μm or less, and even more preferably 500 μm or less.

[0048] The thickness of the solid electrolyte layer 30 is, for example, 1 μm or more up to 30 μm or less, 2 μm or more up to 20 μm or less, or 3 μm or more up to 15 μm or less.

[0049] The thicker the positive electrode 10 and negative electrode 20 are formed, the better the battery capacity. For example, the thickness of the positive electrode 10 and negative electrode 20 is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 20 μm or more. Furthermore, the thickness of the positive electrode 10 and negative electrode 20 is preferably at least 0.5 times the thickness of the solid electrolyte layer 30, more preferably at least 1 time, and even more preferably at least 1.5 times. Alternatively, the positive electrode 10 and negative electrode 20 are preferably thicker than the solid electrolyte layer 30. Note that the thicker the positive electrode 10 and negative electrode 20, the larger the interface area between the blank portion and the electrode when the blank portion is formed in a transverse U-shape, and therefore the more significant the effect of this embodiment.

[0050] On the other hand, if the positive electrode 10 and the negative electrode 20 are too thick, cracks may occur during the heat treatment process after the stacking is formed. Even if no cracks occur, there is a risk that the battery may not respond properly during operation. Therefore, it is preferable to set an upper limit on the thickness of the positive electrode 10 and the negative electrode 20. For example, the thickness of the positive electrode 10 and the negative electrode 20 is preferably 200 μm or less, more preferably 100 μm or less, and even more preferably 80 μm or less. The thickness of the positive electrode 10 and the negative electrode 20 is preferably 200 times or less than the thickness of the solid electrolyte layer 30, more preferably 100 times or less, and even more preferably 80 times or less.

[0051] The thickness of each solid electrolyte layer 30 in the Z-axis direction can be measured by: observing the cross-section of the all-solid-state battery 100a including the Z-axis direction using SEM (Scanning Electron Microscopy), measuring the thickness of each of the 10 different solid electrolyte layers 30 at 10 points, and obtaining the average value of all measurement points. The thickness of each positive electrode 10 in the Z-axis direction can be measured by: observing the cross-section of the all-solid-state battery 100a including the Z-axis direction using SEM, measuring the thickness of each of the 10 different positive electrodes 10 at 10 points, and obtaining the average value of all measurement points. The thickness of each negative electrode 20 in the Z-axis direction can be measured by: observing the cross-section of the all-solid-state battery 100a including the Z-axis direction using SEM, measuring the thickness of each of the 10 different negative electrodes 20 at 10 points, and obtaining the average value of all measurement points.

[0052] Furthermore, if the composition of the positive electrode 10 and the composition of the negative electrode 20 are different, the thermal shrinkage behavior of the positive electrode 10 and the thermal shrinkage behavior of the negative electrode 20 will be different, making cracks more likely to occur. Therefore, the effect of this embodiment can be said to be particularly significant.

[0053] A description of the manufacturing method of the all-solid-state battery 100a will be given. Figure 9 A flowchart illustrating the manufacturing method of the all-solid-state battery 100a is shown.

[0054] (Solid Electrolyte Raw Material Powder Synthesis Process) Raw material powder for the solid electrolyte layer 30 is synthesized. For example, raw material powder for an oxide-based solid electrolyte can be synthesized by mixing raw materials and additives and using a solid-phase synthesis method, etc. The resulting powder is then dry-milled. Therefore, the particle size of the resulting powder is adjusted to the desired particle size. For example, this can be achieved by using a 5 mm... The planetary ball mill with ZrO2 balls adjusts the particle diameter to the desired diameter.

[0055] (Synthesis process of coating material powder) Ceramic raw material powder for coating layer 50 is synthesized. For example, raw material powder for coating layer can be synthesized by mixing raw materials and additives and using solid-phase synthesis method, etc. The obtained raw material powder can be adjusted to the required average particle size by dry pulverizing. For example, using a planetary ball mill with ZrO2 balls of 5 mm in diameter, the particles are adjusted to the required average particle size.

[0056] (Synthesis Process of Raw Material Powder for the White Space) Raw material powders for the positive electrode white space 95a and the negative electrode white space 95b are synthesized. For example, raw material powders for the white space can be synthesized by mixing raw materials and additives and using solid-phase synthesis methods. The obtained raw material powder can be adjusted to the desired average particle size by dry pulverizing. For example, using a planetary ball mill with ZrO2 balls of 5 mm in diameter, the particles are adjusted to the desired average particle size.

[0057] (Preparation Steps for Electrode Slurries) Next, slurries for the positive electrodes 10 and 20 are prepared respectively. For example, the slurries for the positive and negative electrodes can be obtained by uniformly dispersing conductive additives, electrode active materials, solid electrolyte materials, sintering aids, binders, plasticizers, etc., in water or an organic solvent. The slurry for the solid electrolyte described above can be used as a solid electrolyte material. Carbon materials can be used as conductive additives. Metals can be used as conductive additives. Examples of metals as conductive additives are Pd, Ni, Cu, Fe, or alloys containing these. Pd, Ni, Cu, Fe, alloys containing these, and various carbon materials can also be used.

[0058] The sintering aids for the slurry used for the positive electrode and the slurry used for the negative electrode include one or more glass components, such as Li-BO-based compounds, Li-Si-O-based compounds, Li-CO-based compounds, Li-SO-based compounds, and Li-PO-based compounds.

[0059] (Preparation step of slurry for external electrodes) Next, a slurry for the external electrodes used in manufacturing the first external electrode 40a and the second external electrode 40b described above is prepared. For example, a slurry for the external electrodes can be obtained by uniformly dispersing conductive materials, glass frit, binders, plasticizers, etc., in water or an organic solvent.

[0060] (Preparation of Green Sheets) By uniformly dispersing the raw material powder for the solid electrolyte layer together with binders, dispersants, plasticizers, etc., in an aqueous or organic solvent and then wet-milling, a solid electrolyte slurry with the desired average particle size can be prepared. At this time, bead mills, wet jet mills, various kneaders, high-pressure homogenizers, etc., can be used, and from the viewpoint of being able to adjust the particle size distribution while simultaneously dispersing, bead mills are preferred. A binder is added to the obtained solid electrolyte slurry to obtain a slurry for solid electrolytes. Solid electrolyte green sheets can be formed by applying the obtained solid electrolyte slurry. There are no particular limitations on the coating method, and slit coating, reverse coating, gravure coating, rod coating, doctor blade coating, etc., can be used. The particle size distribution after wet milling can be measured using, for example, a laser diffraction measuring device, using laser diffraction scattering.

[0061] (Layering and cutting processes) such as Figure 10 As shown, a paste for the positive electrode is printed on one side of the first solid electrolyte green sheet 51a to form multiple strip-shaped positive electrode patterns 52a. In the gaps between the positive electrode patterns 52a, a paste 53a for the positive electrode blank areas is printed on the first solid electrolyte green sheet 51a. The paste 53a for the positive electrode blank areas can be formed by applying raw material powder for the blank areas using a method similar to the preparation process of the solid electrolyte green sheet. A negative electrode pattern 52b and a paste 53b for the negative electrode blank areas are printed on one side of the second solid electrolyte green sheet 51b. For example, in the gaps between the negative electrode patterns 52b, the paste 53b for the negative electrode blank areas is printed on the second solid electrolyte green sheet 51b. The paste 53b for the negative electrode blank areas can be formed by applying raw material powder for the blank areas using a method similar to the preparation method of the solid electrolyte green sheet.

[0062] like Figure 10 As shown, the printed first solid electrolyte green sheet 51a and the printed second solid electrolyte green sheet 51b are alternately stacked, such that the paste 53a for the positive electrode blank area and the paste 53b for the negative electrode blank area are alternately offset. The cover sheet is pressed from above and below in the stacking direction to obtain a multilayer body.

[0063] Next, as Figure 11As shown, the multilayer body is cut from the Z-axis along the cutting lines extending in the X-axis and Y-axis directions to obtain the multilayer body of the multilayer chip 60 before firing. The multilayer body can be polished by barrel polishing or other methods. Polishing reduces the contact between electrodes and prevents short circuits.

[0064] (Firing process) Next, the obtained green chip is fired to obtain the multilayer chip 60. The firing conditions include but are not limited to an oxidizing or non-oxidizing atmosphere, and the maximum temperature is preferably 400°C to 1000°C, more preferably 500°C to 900°C. A step of maintaining a temperature lower than the maximum temperature in an oxidizing atmosphere can be added to completely remove the binder before reaching the maximum temperature. To reduce the process cost, it is desirable to perform firing at as low a temperature as possible. A re-oxidation process can be performed after firing.

[0065] (External electrode formation step) Next, the slurry for the external electrodes is applied to the two end faces of the multilayer chip 60 and cured to form the first external electrode 41 and the second external electrode 42, thereby obtaining the all-solid-state battery 100a.

[0066] Alternatively, the slurry for the first external electrode and the slurry for the second external electrode can be applied to the two end faces of the green sheet obtained in the lamination and cutting processes, and then fired to form the first external electrode 41 from the slurry for the first external electrode and the second external electrode 42 from the slurry for the second external electrode, thereby obtaining the all-solid-state battery 100a.

[0067] [Examples]

[0068] (Example 1) A laminated all-solid-state battery is manufactured according to the above-described embodiment. The positive electrode active material 11 is LiCo 0.7 Ni 0.3 PO4, which has an average discharge potential of 4.8 V with respect to Li + / Li. The negative electrode active material 21 is TiTa 1.5 Nb 0.5 O7, which has an average discharge potential of about 1.5 V with respect to Li + / Li. The solid-state electrolytes 12 and 22 are Li 1+x Al x Ge 2-x P3O 12 (0 < x < 1). As Figure 10As shown, a multilayer body is formed by alternately layering a first solid electrolyte green sheet 51a coated with a positive electrode pattern 52a and a slurry 53a for the positive electrode blank portion, and a second solid electrolyte green sheet 51b coated with a negative electrode pattern 52b and a slurry 53b for the negative electrode blank portion. Then, a cover sheet is attached to the top and bottom of the multilayer body. After pressing, along... Figure 11 The multilayer body is cut along the dicing lines shown to obtain individual chips. The individual chips are then degreased and fired to obtain 48 chips with… Figure 8 The electrode stack structure shown is an all-solid-state battery chip. The solid electrolyte contained in the slurry 53a for the positive electrode blank and the slurry 53b for the negative electrode blank is the same as the solid electrolyte contained in the first solid electrolyte green sheet 51a and the second solid electrolyte green sheet 51b.

[0069] No cracks or other defects were observed in any of the fired chips. This is believed to be because stress was suppressed during the firing process. This is thought to be because the contact interface between the electrode and the blank area was reduced by not providing the positive electrode blank area 95a on the edge of the first side surface S1 or the edge of the second side surface S2 of the positive electrode 10.

[0070] In addition, such as Figure 7 The external electrode is formed as shown, and the chip is dried in dry air at 70°C. Charge / discharge tests are performed, and no failures occur during the initial charging process of any chip. Therefore, stress during charge / discharge is considered to have been suppressed. This is also believed to be because the contact interface between the electrode and the blank area is reduced by not providing the positive electrode blank area 95a on the edge of the first side surface S1 or the edge of the second side surface S2 of the positive electrode 10. In addition, providing the negative electrode blank area 95b on the edge of the first side surface S1 or the edge of the second side surface S2 of the negative electrode 20 can reduce the drying defect rate and suppress the degradation of electrical characteristics. The charge / discharge test is performed by soldering the chip to the pad pattern substrate and sealing it in a housing.

[0071] The results are shown in Table 1. If no cracks appear during the firing process, the "stress during firing" is considered acceptable (○). If no cracks appear during charging and discharging, the "charging and discharging stress" is considered acceptable (○). Furthermore, if no malfunction occurs during the first charge in the charging and discharging process, the drying defect rate is judged to be acceptable (○).

[0072] [Table 1]

[0073] (Example 2) A tandem all-solid-state battery was manufactured according to the above embodiments. The same positive electrode active material and the same solid electrolyte as in Example 1 were used, and the ratio of Li... ＋ / Li has an average discharge potential of approximately 1.6 V for Al 0.9 Hf 0.1 Nb9Ta2O 29 Used in negative electrode active materials. For example... Figure 10 As shown, a first solid electrolyte green sheet 51a coated with a positive electrode pattern 52a and a slurry 53a for the positive electrode blank area is alternately stacked with a second solid electrolyte green sheet 51b coated with a negative electrode pattern 52b and a slurry 53b for the negative electrode blank area to form a multilayer body. Then, a cover sheet is attached to the top and bottom. After pressing, along... Figure 11 The multilayer body is cut using the dicing lines shown to obtain individual chips. The individual chips are then degreased and fired to obtain 48 units with… Figure 8 The electrode stack structure shown is an all-solid-state battery chip. The solid electrolyte contained in the slurry 53a for the positive electrode blank and the slurry 53b for the negative electrode blank is the same as the solid electrolyte contained in the first solid electrolyte green sheet 51a and the second solid electrolyte green sheet 51b.

[0074] No cracks or other defects were observed in any of the chips after firing. Therefore, it is believed that stress was suppressed during the firing process. This is thought to be because the positive electrode blank 95a was not provided on the edge of the first side surface S1 or the edge of the second side surface S2 of the positive electrode 10, thereby reducing the contact interface between the electrode and the blank.

[0075] In addition, such as Figure 7 The external electrodes are formed as shown, and the chips are dried in dry air at 70°C. Charge / discharge tests are performed, and no failures occur during the initial charging process of any chip. Therefore, it is believed that stress during charge / discharge is also suppressed. This is also believed to be due to the fact that no positive electrode blank 95a is provided on the edge of the first side surface S1 or the edge of the second side surface S2 of the positive electrode 10, thereby reducing the contact interface between the electrode and the blank. Furthermore, a negative electrode blank 95b is provided on the edge of the first side surface S1 or the edge of the second side surface S2 of the negative electrode 20, thereby suppressing moisture adhesion and reducing the degradation of electrical characteristics. Note that the charge / discharge tests are performed by soldering the chip onto a pad pattern substrate and sealing it in a housing.

[0076] (Example 3) A stacked all-solid-state battery was manufactured according to the above embodiment. The same positive electrode active material 11 and the same solid electrolytes 12 and 22 as in Example 1 were used, and the negative electrode active material 21 was Li having a NASICON structure. 1+x AlxTi 2-x P3O 12 (0≤x<1), and the average discharge potential relative to Li ＋ / Li is approximately 2.4 V. For example... Figure 10 As shown, a multilayer body is formed by alternately layering a first solid electrolyte green sheet 51a coated with a positive electrode pattern 52a and a slurry 53a for the positive electrode blank portion, and a second solid electrolyte green sheet 51b coated with a negative electrode pattern 52b and a slurry 53b for the negative electrode blank portion. A cover sheet is then attached to the top and bottom of the multilayer body. After pressing, along... Figure 11 The dicing lines shown are used to cut a multilayer body to form individual chips. The individual chips are then degreased and fired to obtain 48 chips with… Figure 8 The electrode stack structure shown is an all-solid-state battery chip. The solid electrolyte contained in the slurry 53a for the positive electrode blank and the slurry 53b for the negative electrode blank is the same as the solid electrolyte contained in the first solid electrolyte green sheet 51a and the second solid electrolyte green sheet 51b.

[0077] No cracks or other defects were observed in any of the fired chips. It is believed that stress was suppressed during the firing process. This is thought to be because the positive electrode blank 95a was not provided on the edge of the first side surface S1 side and the edge of the second side surface S2 side of the positive electrode 10, thereby reducing the contact interface between the electrode and the blank 95a.

[0078] In addition, such as Figure 7 The external electrodes are formed as shown, and the chips are dried in dry air at 70°C. Charge-discharge tests were performed, and no failures occurred during the initial charging of any chip. Therefore, stress during charging and discharging is considered to have been suppressed. This is also believed to be due to the fact that no positive electrode blank 95a is provided on the edge of the first side surface S1 or the edge of the second side surface S2 of the positive electrode 10, thereby reducing the contact interface between the electrode and the blank. Furthermore, the negative electrode blank 95b is provided on the edge of the first side surface S1 or the edge of the second side surface S2 of the negative electrode 20, thereby suppressing moisture adhesion and reducing the degradation of electrical characteristics. Charge-discharge tests were performed by soldering the chips onto a pad pattern substrate and sealing them in a housing.

[0079] (Comparative Example 1) The same positive electrode active material 11, negative electrode active material 21, and solid electrolytes 12 and 22 as in Example 1 were used. A first solid electrolyte green sheet 51a coated with a positive electrode pattern 52a and a slurry 53a for the positive electrode blank portion, and a second solid electrolyte green sheet 51b coated with a negative electrode pattern 52b and a slurry 53b for the negative electrode blank portion were alternately stacked to form a multilayer body. A cover layer was then provided on the top and bottom of the multilayer body, which was then press-molded and cut into the shape shown. Figure 12 The multilayer chip is shown. These fragments are then degreased and fired to obtain 48 all-solid-state battery chips. Therefore, in Comparative Example 1, after firing, neither the positive electrode 10 nor the negative electrode 20 extends to the first side S1 nor to the second side S2, and both the positive electrode 10 and the negative electrode 20 are covered by the blank portions on the first side S1 and the second side S2.

[0080] In Comparative Example 1, visually perceptible cracks were observed in 6 out of 48 chips. This is believed to be because the blank areas on the edges of the positive electrode 10 and negative electrode 20 facing the first side surface S1 and the second side surface S2 increase the contact interface area between the electrode and the blank areas, thereby increasing the internal stress. Therefore, the stress during the firing process is considered unacceptable (x).

[0081] Forty-two crack-free chips were formed using external electrodes and dried in dry air at 70°C. Charge-discharge tests were performed, and a soft short-circuit fault was confirmed during the initial charging of 10 chips. This was attributed to the increased area of ​​the contact interface between the electrodes and the blank areas on the edges of the positive electrode 10 and the negative electrode 20 facing the first side surface S1 and the second side surface S2, leading to internal microcrack growth due to volume changes in the electrodes during charging, resulting in multilayer structure misalignment. Therefore, the stress during charge-discharge was considered unacceptable (x).

[0082] (Comparative Example 2) The same positive electrode active material 11, negative electrode active material 21, and solid electrolytes 12 and 22 as in Example 1 were used. A first solid electrolyte green sheet 51a coated with a positive electrode pattern 52a and a paste 53a for the positive electrode blank area was alternately laminated with a second solid electrolyte green sheet 51b coated with a negative electrode pattern 52b and a paste 53b for the negative electrode blank area to form a multilayer. A capping layer was then applied to the top and bottom of the multilayer, and the multilayer was cut after pressing. The resulting chip has… Figure 13 The multilayer structure is shown. It is then degreased and sintered to obtain 48 all-solid-state battery chips. Therefore, in Comparative Example 2, both the positive electrode 10 and the negative electrode 20 extend to the first and second side surfaces.

[0083] In Comparative Example 2, no cracks or other defects were observed in any of the chips after firing. This is believed to be because the positive electrode 10 and the negative electrode 20 were not covered by the blank areas on the first side surface S1 and the second side surface S2, thereby reducing the contact interface between the electrodes and the blank areas and reducing internal stress.

[0084] External electrodes were then formed, and the chips were dried in dry air at 70°C. Charge / discharge tests were performed, and 45 chips operated without failure. However, three chips exhibited poor drying, with coulombic efficiencies of 70% or lower during the initial charge / discharge process (drying failure rate = 3 / 45 × 100% = 6%). This was attributed to the negative electrode, with a lower average operating potential than the positive electrode, extending to both the first and second side surfaces, thus inducing side reactions between the negative electrode and the adhering moisture during charge / discharge operations.

[0085] (Comparative Example 3) The same positive electrode active material 11, negative electrode active material 21, and solid electrolytes 12 and 22 as in Example 1 were used. A first solid electrolyte green sheet 51a coated with a positive electrode pattern 52a and a paste 53a for the positive electrode blank area was alternately laminated with a second solid electrolyte green sheet 51b coated with a negative electrode pattern 52b and a paste 53b for the negative electrode blank area to form a multilayer. A capping layer was then applied to the top and bottom of the multilayer, and the multilayer was press-molded and cut. The resulting chip has… Figure 14 The multilayer structure is shown. These are then degreased and fired to obtain 48 all-solid-state battery chips. Therefore, in Comparative Example 3, the positive electrode 10 does not extend to the first side surface S1 and the second side surface S2, while the positive electrode 10 in the embodiment extends to the first side surface S1 and the second side surface S2. For the positive electrode 10, there are blank areas covering the first side surface S1 and the second side surface S2.

[0086] In Comparative Example 3, no cracks or other defects were observed in any chip after firing. This is believed to be because the edges of the negative electrode 20 on the first side surface S1 and the second side surface S2 were not covered by the blank portion, thereby reducing the contact interface between the electrode and the blank portion and reducing internal stress.

[0087] External electrodes were then formed, and the chips were dried in dry air at 70°C. Charge / discharge tests were performed, and 45 chips operated without failure. However, three chips exhibited poor drying, with coulombic efficiencies of 70% or lower during the initial charge / discharge process (drying failure rate = 3 / 45 × 100% = 6%). This was attributed to the negative electrode, with a lower average operating potential than the positive electrode, extending to both the first and second surfaces, thus inducing side reactions between the negative electrode and the adhering moisture during charge / discharge operations.

[0088] (Battery Energy Density) Next, the battery voltages of the all-solid-state battery chips of Examples 1 to 3 and Comparative Examples 1 to 3 were measured. The battery voltage of Example 1 was 3.2 V, the battery voltage of Example 2 was 3.1 V, the battery voltage of Example 3 was 2.3 V, and the battery voltage of Comparative Examples 1 to 3 was 3.2 V. Therefore, the battery voltage and energy density in Examples 1 and 2 were higher than those in Example 3. This is because the average operating potential of the negative electrode active material in Examples 1 and 2 relative to Li / Li ＋ Less than 2 V.

[0089] Although embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions and modifications can be made thereto without departing from the spirit and scope of the invention.

Claims

1. An all-solid-state battery, the all-solid-state battery comprising: A first electrode layer, the first electrode layer including a first electrode and a first blank portion, the first electrode including a first electrode active material and being quadrilateral in a plan view, the first blank portion being quadrilateral in a plan view, the first electrode layer being formed by connecting the first electrode and the first blank portion; The second electrode layer includes a second electrode and a second blank portion. The second electrode has a quadrilateral shape in a plan view and includes a second electrode active material. The second electrode active material has an average operating potential lower than that of the first electrode active material. The second blank portion is connected to one side of the quadrilateral shape of the second electrode. The quadrilateral shape has a first side and a second side adjacent to the first side. The second blank portion extends to the first side. as well as A solid electrolyte layer is disposed between the first electrode layer and the second electrode layer.

2. The all-solid-state battery according to claim 1, in, The second blank portion extends to contact the entire first side and the entire second side of the second electrode.

3. The all-solid-state battery according to claim 1 or 2, in, In the plan view, the solid electrolyte layer is quadrilateral, and the quadrilateral of the solid electrolyte layer and the quadrilateral of the first electrode layer roughly overlap with each other.

4. The all-solid-state battery according to any one of claims 1 to 3, in, In the region connected to the first side of the second electrode, in a plan view of the second electrode layer, the width of the second blank portion facing the first side is 50 μm or greater up to 1000 μm or less.

5. The all-solid-state battery according to any one of claims 1 to 4, in, The second blank portion contains the same solid electrolyte composition as the solid electrolyte layer.

6. The all-solid-state battery according to any one of claims 1 to 5, in, The solid electrolyte contained in the solid electrolyte layer is an oxide-based solid electrolyte.

7. The all-solid-state battery according to any one of claims 1 to 6, in, The average operating potential of the second electrode active material relative to Li / Li ＋ Less than 2 V.

8. The all-solid-state battery according to any one of claims 1 to 7, wherein the all-solid-state battery further comprises: The first terminal is in contact with the first electrode, the solid electrolyte layer, and the second remaining portion; as well as The second terminal is in contact with the second electrode, the solid electrolyte layer, and the first remaining portion.

9. An all-solid-state battery, the all-solid-state battery comprising: A first electrode layer, comprising a first electrode and a first blank portion, wherein the first electrode comprises a first electrode active material and is quadrilateral in plan view, and the first blank portion is quadrilateral in plan view, the first electrode layer is formed by connecting the first electrode and the first blank portion, wherein the first electrode active material is capable of absorbing and releasing lithium ions, and the first electrode active material is an oxide containing lithium and includes at least one element selected from the group consisting of titanium, vanadium, manganese, iron, cobalt, nickel, phosphorus and silicon; A second electrode layer, comprising a second electrode and a second blank portion, wherein the second electrode has a quadrilateral shape in a plan view and includes a second electrode active material having a lower average operating potential than the first electrode active material, the second blank portion being connected to one side of the quadrilateral shape of the second electrode having a first side and a second side adjacent to said side, the second blank portion extending to the first side, the second electrode active material being capable of absorbing and releasing lithium ions, and the second electrode active material being any one of an oxide, a conductive carbon material, a elemental metal, or an alloy comprising at least one element selected from the group consisting of lithium, titanium, niobium, tantalum, and hafnium; and A solid electrolyte layer is disposed between the first electrode layer and the second electrode layer.

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